[v13,7/9] ACPI: Translate the I/O range of non-MMIO devices before scanning

Message ID 1518543933-22456-8-git-send-email-john.garry@huawei.com
State Not Applicable
Headers show
Series
  • LPC: legacy ISA I/O support
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Commit Message

John Garry Feb. 13, 2018, 5:45 p.m.
On some platforms (such as arm64-based hip06/hip07), access to legacy
ISA/LPC devices through access IO space is required, similar to x86
platforms. As the I/O for these devices are not memory mapped like
PCI/PCIE MMIO host bridges, they require special low-level device
operations through some host to generate IO accesses, i.e. a non-
transparent bridge.

Through the logical PIO framework, hosts are able to register address
ranges in the logical PIO space for IO accesses. For hosts which require
a LLDD to generate the IO accesses, through the logical PIO framework
the host also registers accessors as a backend to generate the physical
bus transactions for IO space accesses (called indirect IO).

When describing the indirect IO child device in APCI tables, the IO
resource is the host-specific address for the child (generally a
bus address).
An example is as follows:
  Device (LPC0) {
    Name (_HID, "HISI0191")  // HiSi LPC
    Name (_CRS, ResourceTemplate () {
      Memory32Fixed (ReadWrite, 0xa01b0000, 0x1000)
    })
  }

  Device (LPC0.IPMI) {
    Name (_HID, "IPI0001")
    Name (LORS, ResourceTemplate() {
      QWordIO (
        ResourceConsumer,
	MinNotFixed,     // _MIF
	MaxNotFixed,     // _MAF
	PosDecode,
	EntireRange,
	0x0,             // _GRA
	0xe4,            // _MIN
	0x3fff,          // _MAX
	0x0,             // _TRA
	0x04,            // _LEN
	, ,
	BTIO
      )
    })

Since the IO resource for the child is a host-specific address,
special translation are required to retrieve the logical PIO address
for that child.

To overcome the problem of associating this logical PIO address
with the child device, a scan handler is added to scan the ACPI
namespace for known indirect IO hosts. This scan handler creates an
MFD per child with the translated logical PIO address as it's IO
resource, as a substitute for the normal platform device which ACPI
would create during device enumeration.

Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Zhichang Yuan <yuanzhichang@hisilicon.com>
Signed-off-by: Gabriele Paoloni <gabriele.paoloni@huawei.com>
---
 drivers/acpi/arm64/Makefile          |   1 +
 drivers/acpi/arm64/acpi_indirectio.c | 250 +++++++++++++++++++++++++++++++++++
 drivers/acpi/internal.h              |   5 +
 drivers/acpi/scan.c                  |   1 +
 4 files changed, 257 insertions(+)
 create mode 100644 drivers/acpi/arm64/acpi_indirectio.c

Comments

Rafael J. Wysocki Feb. 14, 2018, 9:21 a.m. | #1
On Tue, Feb 13, 2018 at 6:45 PM, John Garry <john.garry@huawei.com> wrote:
> On some platforms (such as arm64-based hip06/hip07), access to legacy
> ISA/LPC devices through access IO space is required, similar to x86
> platforms. As the I/O for these devices are not memory mapped like
> PCI/PCIE MMIO host bridges, they require special low-level device
> operations through some host to generate IO accesses, i.e. a non-
> transparent bridge.
>
> Through the logical PIO framework, hosts are able to register address
> ranges in the logical PIO space for IO accesses. For hosts which require
> a LLDD to generate the IO accesses, through the logical PIO framework
> the host also registers accessors as a backend to generate the physical
> bus transactions for IO space accesses (called indirect IO).
>
> When describing the indirect IO child device in APCI tables, the IO
> resource is the host-specific address for the child (generally a
> bus address).
> An example is as follows:
>   Device (LPC0) {
>     Name (_HID, "HISI0191")  // HiSi LPC
>     Name (_CRS, ResourceTemplate () {
>       Memory32Fixed (ReadWrite, 0xa01b0000, 0x1000)
>     })
>   }
>
>   Device (LPC0.IPMI) {
>     Name (_HID, "IPI0001")
>     Name (LORS, ResourceTemplate() {
>       QWordIO (
>         ResourceConsumer,
>         MinNotFixed,     // _MIF
>         MaxNotFixed,     // _MAF
>         PosDecode,
>         EntireRange,
>         0x0,             // _GRA
>         0xe4,            // _MIN
>         0x3fff,          // _MAX
>         0x0,             // _TRA
>         0x04,            // _LEN
>         , ,
>         BTIO
>       )
>     })
>
> Since the IO resource for the child is a host-specific address,
> special translation are required to retrieve the logical PIO address
> for that child.
>
> To overcome the problem of associating this logical PIO address
> with the child device, a scan handler is added to scan the ACPI
> namespace for known indirect IO hosts. This scan handler creates an
> MFD per child with the translated logical PIO address as it's IO
> resource, as a substitute for the normal platform device which ACPI
> would create during device enumeration.
>
> Signed-off-by: John Garry <john.garry@huawei.com>
> Signed-off-by: Zhichang Yuan <yuanzhichang@hisilicon.com>
> Signed-off-by: Gabriele Paoloni <gabriele.paoloni@huawei.com>

Just a few minor nits below.

> ---
>  drivers/acpi/arm64/Makefile          |   1 +
>  drivers/acpi/arm64/acpi_indirectio.c | 250 +++++++++++++++++++++++++++++++++++
>  drivers/acpi/internal.h              |   5 +
>  drivers/acpi/scan.c                  |   1 +
>  4 files changed, 257 insertions(+)
>  create mode 100644 drivers/acpi/arm64/acpi_indirectio.c
>
> diff --git a/drivers/acpi/arm64/Makefile b/drivers/acpi/arm64/Makefile
> index 1017def..f4a7f46 100644
> --- a/drivers/acpi/arm64/Makefile
> +++ b/drivers/acpi/arm64/Makefile
> @@ -1,2 +1,3 @@
>  obj-$(CONFIG_ACPI_IORT)        += iort.o
>  obj-$(CONFIG_ACPI_GTDT)        += gtdt.o
> +obj-$(CONFIG_INDIRECT_PIO)     += acpi_indirectio.o
> diff --git a/drivers/acpi/arm64/acpi_indirectio.c b/drivers/acpi/arm64/acpi_indirectio.c
> new file mode 100644
> index 0000000..51a1b92
> --- /dev/null
> +++ b/drivers/acpi/arm64/acpi_indirectio.c
> @@ -0,0 +1,250 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2017 HiSilicon Limited, All Rights Reserved.
> + * Author: Gabriele Paoloni <gabriele.paoloni@huawei.com>
> + * Author: Zhichang Yuan <yuanzhichang@hisilicon.com>
> + * Author: John Garry <john.garry@huawei.com>
> + *
> + * This file implements functunality to scan the ACPI namespace and config
> + * devices under "indirect IO" hosts. An "indirect IO" host allows child
> + * devices to use logical IO accesses when the host, itself, does not provide
> + * a transparent bridge. The device setup creates a per-child MFD with a
> + * logical port IO resource.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/logic_pio.h>
> +#include <linux/mfd/core.h>
> +#include <linux/platform_device.h>
> +
> +ACPI_MODULE_NAME("indirect IO");
> +
> +#define ACPI_INDIRECT_IO_NAME_LEN 255
> +
> +struct acpi_indirect_io_mfd_cell {
> +       struct mfd_cell_acpi_match acpi_match;
> +       char name[ACPI_INDIRECT_IO_NAME_LEN];
> +       char pnpid[ACPI_INDIRECT_IO_NAME_LEN];
> +};
> +
> +static int acpi_indirect_io_xlat_res(struct acpi_device *adev,
> +                                    struct acpi_device *host,
> +                                    struct resource *res)
> +{
> +       unsigned long sys_port;
> +       resource_size_t len = res->end - res->start;
> +
> +       sys_port = logic_pio_trans_hwaddr(&host->fwnode, res->start, len);
> +       if (sys_port == -1UL)
> +               return -EFAULT;
> +
> +       res->start = sys_port;
> +       res->end = sys_port + len;
> +
> +       return 0;
> +}
> +
> +/*
> + * acpi_indirect_io_set_res - set the resources for a child device
> + * (MFD) of an "indirect IO" host.

The above should fit into a single line.

I'd make it something like "acpi_indirect_io_set_res - set "indirect
IO" host child (MFD) resources" and it already is explained in the
comment below.

> + * @child: the device node to be updated the I/O resource
> + * @hostdev: the device node associated with the "indirect IO" host
> + * @res: double pointer to be set to the address of translated resources
> + * @num_res: pointer to variable to hold the number of translated resources
> + *
> + * Returns 0 when successful, and a negative value for failure.
> + *
> + * For a given "indirect IO" host, each child device will have associated
> + * host-relevative address resource. This function will return the translated

host-relative

> + * logical PIO addresses for each child devices resources.
> + */
> +static int acpi_indirect_io_set_res(struct device *child,
> +                                   struct device *hostdev,
> +                                   const struct resource **res,
> +                                   int *num_res)
> +{
> +       struct acpi_device *adev;
> +       struct acpi_device *host;
> +       struct resource_entry *rentry;
> +       LIST_HEAD(resource_list);
> +       struct resource *resources;
> +       int count;
> +       int i;
> +       int ret = -EIO;
> +
> +       if (!child || !hostdev)
> +               return -EINVAL;
> +
> +       host = to_acpi_device(hostdev);
> +       adev = to_acpi_device(child);
> +
> +       /* check the device state */
> +       if (!adev->status.present) {
> +               dev_info(child, "device is not present\n");

dev_dbg()?

> +               return 0;
> +       }
> +       /* whether the child had been enumerated? */
> +       if (acpi_device_enumerated(adev)) {
> +               dev_info(child, "had been enumerated\n");

Again, dev_dbg()?

> +               return 0;
> +       }
> +
> +       count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
> +       if (count <= 0) {
> +               dev_err(child, "failed to get resources\n");

I'd use dev_dbg() here too (the message may not even be meaningful to a user).

> +               return count ? count : -EIO;
> +       }
> +
> +       resources = kcalloc(count, sizeof(*resources), GFP_KERNEL);
> +       if (!resources) {

And you don't print anything here, I wonder why?

> +               acpi_dev_free_resource_list(&resource_list);
> +               return -ENOMEM;
> +       }
> +       count = 0;
> +       list_for_each_entry(rentry, &resource_list, node)
> +               resources[count++] = *rentry->res;
> +
> +       acpi_dev_free_resource_list(&resource_list);
> +
> +       /* translate the I/O resources */
> +       for (i = 0; i < count; i++) {
> +               if (!(resources[i].flags & IORESOURCE_IO))
> +                       continue;
> +               ret = acpi_indirect_io_xlat_res(adev, host, &resources[i]);
> +               if (ret) {
> +                       kfree(resources);
> +                       dev_err(child, "translate IO range failed(%d)\n", ret);
> +                       return ret;
> +               }
> +       }
> +       *res = resources;
> +       *num_res = count;
> +
> +       return ret;
> +}
> +
> +/*
> + * acpi_indirect_io_setup - scan handler for "indirect IO" host.
> + * @adev: "indirect IO" host ACPI device pointer

One extra empty comment line here, please.

> + * Returns 0 when successful, and a negative value for failure.
> + *
> + * Setup an "indirect IO" host by scanning all child devices, and
> + * create a per-device MFD with logical PIO translated IO resources.
> + */
> +static int acpi_indirect_io_setup(struct acpi_device *adev)
> +{
> +       struct platform_device *pdev;
> +       struct mfd_cell *mfd_cells;
> +       struct logic_pio_hwaddr *range;
> +       struct acpi_device *child;
> +       struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cells;
> +       int size, ret, count = 0, cell_num = 0;
> +
> +       range = kzalloc(sizeof(*range), GFP_KERNEL);
> +       if (!range)
> +               return -ENOMEM;
> +       range->fwnode = &adev->fwnode;
> +       range->flags = PIO_INDIRECT;
> +       range->size = PIO_INDIRECT_SIZE;
> +
> +       ret = logic_pio_register_range(range);
> +       if (ret)
> +               goto free_range;
> +
> +       list_for_each_entry(child, &adev->children, node)
> +               cell_num++;
> +
> +       /* allocate the mfd cell and companion acpi info, one per child */
> +       size = sizeof(*mfd_cells) + sizeof(*acpi_indirect_io_mfd_cells);
> +       mfd_cells = kcalloc(cell_num, size, GFP_KERNEL);
> +       if (!mfd_cells) {
> +               ret = -ENOMEM;
> +               goto free_range;
> +       }
> +
> +       acpi_indirect_io_mfd_cells = (struct acpi_indirect_io_mfd_cell *)
> +                                       &mfd_cells[cell_num];
> +       /* Only consider the children of the host */
> +       list_for_each_entry(child, &adev->children, node) {
> +               struct mfd_cell *mfd_cell = &mfd_cells[count];
> +               struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cell =
> +                                       &acpi_indirect_io_mfd_cells[count];
> +               const struct mfd_cell_acpi_match *acpi_match =
> +                                       &acpi_indirect_io_mfd_cell->acpi_match;
> +               char *name = &acpi_indirect_io_mfd_cell[count].name[0];
> +               char *pnpid = &acpi_indirect_io_mfd_cell[count].pnpid[0];
> +               struct mfd_cell_acpi_match match = {
> +                       .pnpid = pnpid,
> +               };
> +
> +               snprintf(name, ACPI_INDIRECT_IO_NAME_LEN, "indirect-io-%s",
> +                        acpi_device_hid(child));
> +               snprintf(pnpid, ACPI_INDIRECT_IO_NAME_LEN, "%s",
> +                        acpi_device_hid(child));
> +
> +               memcpy((void *)acpi_match, (void *)&match, sizeof(*acpi_match));
> +               mfd_cell->name = name;
> +               mfd_cell->acpi_match = acpi_match;
> +
> +               ret = acpi_indirect_io_set_res(&child->dev, &adev->dev,
> +                                              &mfd_cell->resources,
> +                                              &mfd_cell->num_resources);
> +               if (ret) {
> +                       dev_err(&child->dev, "set resource failed (%d)\n", ret);

Again, please consider using dev_dbg() here and below (for the same
reason as above).

> +                       goto free_mfd_resources;
> +               }
> +               count++;
> +       }
> +
> +       pdev = acpi_create_platform_device(adev, NULL);
> +       if (IS_ERR_OR_NULL(pdev)) {
> +               dev_err(&adev->dev, "create platform device for host failed\n");
> +               ret = PTR_ERR(pdev);
> +               goto free_mfd_resources;
> +       }
> +       acpi_device_set_enumerated(adev);
> +
> +       ret = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
> +                             mfd_cells, cell_num, NULL, 0, NULL);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to add mfd cells (%d)\n", ret);
> +               goto free_mfd_resources;
> +       }
> +
> +       return ret;

return 0;

You know that ret must be 0 here anyway.

> +
> +free_mfd_resources:
> +       while (cell_num--)
> +               kfree(mfd_cells[cell_num].resources);
> +       kfree(mfd_cells);
> +free_range:
> +       kfree(range);
> +
> +       return ret;
> +}
> +
> +/* All the host devices which apply indirect-IO can be listed here. */
> +static const struct acpi_device_id acpi_indirect_io_host_id[] = {
> +       {}
> +};
> +
> +static int acpi_indirect_io_attach(struct acpi_device *adev,
> +                                  const struct acpi_device_id *id)
> +{
> +       int ret = acpi_indirect_io_setup(adev);
> +
> +       if (ret < 0)
> +               return ret;
> +
> +       return 1;

The above can be written as

return ret < 0 ? ret : 1;

to save a few lines of code (you are using this pattern above, so why
not here?).

> +}
> +
> +static struct acpi_scan_handler acpi_indirect_io_handler = {
> +       .ids = acpi_indirect_io_host_id,
> +       .attach = acpi_indirect_io_attach,
> +};
> +
> +void __init acpi_indirect_io_scan_init(void)
> +{
> +       acpi_scan_add_handler(&acpi_indirect_io_handler);
> +}
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index 1d0a501..680f3cf 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -31,6 +31,11 @@
>  void acpi_platform_init(void);
>  void acpi_pnp_init(void);
>  void acpi_int340x_thermal_init(void);
> +#ifdef CONFIG_INDIRECT_PIO
> +void acpi_indirect_io_scan_init(void);
> +#else
> +static inline void acpi_indirect_io_scan_init(void) {}
> +#endif
>  #ifdef CONFIG_ARM_AMBA
>  void acpi_amba_init(void);
>  #else
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 8e63d93..204da8a 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -2155,6 +2155,7 @@ int __init acpi_scan_init(void)
>         acpi_amba_init();
>         acpi_watchdog_init();
>         acpi_init_lpit();
> +       acpi_indirect_io_scan_init();
>
>         acpi_scan_add_handler(&generic_device_handler);
>
> --

But generally

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

for the generic ACPI changes.
John Garry Feb. 14, 2018, 12:48 p.m. | #2
>> Signed-off-by: John Garry <john.garry@huawei.com>
>> Signed-off-by: Zhichang Yuan <yuanzhichang@hisilicon.com>
>> Signed-off-by: Gabriele Paoloni <gabriele.paoloni@huawei.com>
>

Hi Rafael,

Thanks for checking again.

> Just a few minor nits below.
>
>> ---
>>  drivers/acpi/arm64/Makefile          |   1 +
>>  drivers/acpi/arm64/acpi_indirectio.c | 250 +++++++++++++++++++++++++++++++++++
>>  drivers/acpi/internal.h              |   5 +
>>  drivers/acpi/scan.c                  |   1 +
>>  4 files changed, 257 insertions(+)
>>  create mode 100644 drivers/acpi/arm64/acpi_indirectio.c
>>
>> diff --git a/drivers/acpi/arm64/Makefile b/drivers/acpi/arm64/Makefile
>> index 1017def..f4a7f46 100644
>> --- a/drivers/acpi/arm64/Makefile
>> +++ b/drivers/acpi/arm64/Makefile
>> @@ -1,2 +1,3 @@
>>  obj-$(CONFIG_ACPI_IORT)        += iort.o
>>  obj-$(CONFIG_ACPI_GTDT)        += gtdt.o
>> +obj-$(CONFIG_INDIRECT_PIO)     += acpi_indirectio.o
>> diff --git a/drivers/acpi/arm64/acpi_indirectio.c b/drivers/acpi/arm64/acpi_indirectio.c
>> new file mode 100644
>> index 0000000..51a1b92
>> --- /dev/null
>> +++ b/drivers/acpi/arm64/acpi_indirectio.c
>> @@ -0,0 +1,250 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * Copyright (C) 2017 HiSilicon Limited, All Rights Reserved.
>> + * Author: Gabriele Paoloni <gabriele.paoloni@huawei.com>
>> + * Author: Zhichang Yuan <yuanzhichang@hisilicon.com>
>> + * Author: John Garry <john.garry@huawei.com>
>> + *
>> + * This file implements functunality to scan the ACPI namespace and config
>> + * devices under "indirect IO" hosts. An "indirect IO" host allows child
>> + * devices to use logical IO accesses when the host, itself, does not provide
>> + * a transparent bridge. The device setup creates a per-child MFD with a
>> + * logical port IO resource.
>> + */
>> +
>> +#include <linux/acpi.h>
>> +#include <linux/logic_pio.h>
>> +#include <linux/mfd/core.h>
>> +#include <linux/platform_device.h>
>> +
>> +ACPI_MODULE_NAME("indirect IO");
>> +
>> +#define ACPI_INDIRECT_IO_NAME_LEN 255
>> +
>> +struct acpi_indirect_io_mfd_cell {
>> +       struct mfd_cell_acpi_match acpi_match;
>> +       char name[ACPI_INDIRECT_IO_NAME_LEN];
>> +       char pnpid[ACPI_INDIRECT_IO_NAME_LEN];
>> +};
>> +
>> +static int acpi_indirect_io_xlat_res(struct acpi_device *adev,
>> +                                    struct acpi_device *host,
>> +                                    struct resource *res)
>> +{
>> +       unsigned long sys_port;
>> +       resource_size_t len = res->end - res->start;
>> +
>> +       sys_port = logic_pio_trans_hwaddr(&host->fwnode, res->start, len);
>> +       if (sys_port == -1UL)
>> +               return -EFAULT;
>> +
>> +       res->start = sys_port;
>> +       res->end = sys_port + len;
>> +
>> +       return 0;
>> +}
>> +
>> +/*
>> + * acpi_indirect_io_set_res - set the resources for a child device
>> + * (MFD) of an "indirect IO" host.
>
> The above should fit into a single line.
>
> I'd make it something like "acpi_indirect_io_set_res - set "indirect
> IO" host child (MFD) resources" and it already is explained in the
> comment below.

Fine

>
>> + * @child: the device node to be updated the I/O resource
>> + * @hostdev: the device node associated with the "indirect IO" host
>> + * @res: double pointer to be set to the address of translated resources
>> + * @num_res: pointer to variable to hold the number of translated resources
>> + *
>> + * Returns 0 when successful, and a negative value for failure.
>> + *
>> + * For a given "indirect IO" host, each child device will have associated
>> + * host-relevative address resource. This function will return the translated
>
> host-relative

right

>
>> + * logical PIO addresses for each child devices resources.
>> + */
>> +static int acpi_indirect_io_set_res(struct device *child,
>> +                                   struct device *hostdev,
>> +                                   const struct resource **res,
>> +                                   int *num_res)
>> +{
>> +       struct acpi_device *adev;
>> +       struct acpi_device *host;
>> +       struct resource_entry *rentry;
>> +       LIST_HEAD(resource_list);
>> +       struct resource *resources;
>> +       int count;
>> +       int i;
>> +       int ret = -EIO;
>> +
>> +       if (!child || !hostdev)
>> +               return -EINVAL;
>> +
>> +       host = to_acpi_device(hostdev);
>> +       adev = to_acpi_device(child);
>> +
>> +       /* check the device state */
>> +       if (!adev->status.present) {
>> +               dev_info(child, "device is not present\n");
>
> dev_dbg()?
>
>> +               return 0;
>> +       }
>> +       /* whether the child had been enumerated? */
>> +       if (acpi_device_enumerated(adev)) {
>> +               dev_info(child, "had been enumerated\n");
>
> Again, dev_dbg()?

sure, I think that these can be downgraded

>
>> +               return 0;
>> +       }
>> +
>> +       count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
>> +       if (count <= 0) {
>> +               dev_err(child, "failed to get resources\n");
>
> I'd use dev_dbg() here too (the message may not even be meaningful to a user).

I think that it could be ok - having no resources is not really an "error".

>
>> +               return count ? count : -EIO;
>> +       }
>> +
>> +       resources = kcalloc(count, sizeof(*resources), GFP_KERNEL);
>> +       if (!resources) {
>
> And you don't print anything here, I wonder why?

As I see, we generally don't print out-of-memory failure as we expect 
the alloc code to do it.

But I agree it's useful as we know the point of failure in the driver 
and can add diagnostic info like count value, as maybe we're trying to 
allocate a huge amount of memory.

>
>> +               acpi_dev_free_resource_list(&resource_list);
>> +               return -ENOMEM;
>> +       }
>> +       count = 0;
>> +       list_for_each_entry(rentry, &resource_list, node)
>> +               resources[count++] = *rentry->res;
>> +
>> +       acpi_dev_free_resource_list(&resource_list);
>> +
>> +       /* translate the I/O resources */
>> +       for (i = 0; i < count; i++) {
>> +               if (!(resources[i].flags & IORESOURCE_IO))
>> +                       continue;
>> +               ret = acpi_indirect_io_xlat_res(adev, host, &resources[i]);
>> +               if (ret) {
>> +                       kfree(resources);
>> +                       dev_err(child, "translate IO range failed(%d)\n", ret);
>> +                       return ret;
>> +               }
>> +       }
>> +       *res = resources;
>> +       *num_res = count;
>> +
>> +       return ret;
>> +}
>> +
>> +/*
>> + * acpi_indirect_io_setup - scan handler for "indirect IO" host.
>> + * @adev: "indirect IO" host ACPI device pointer
>
> One extra empty comment line here, please.

ok

>
>> + * Returns 0 when successful, and a negative value for failure.
>> + *
>> + * Setup an "indirect IO" host by scanning all child devices, and
>> + * create a per-device MFD with logical PIO translated IO resources.
>> + */
>> +static int acpi_indirect_io_setup(struct acpi_device *adev)
>> +{
>> +       struct platform_device *pdev;
>> +       struct mfd_cell *mfd_cells;
>> +       struct logic_pio_hwaddr *range;
>> +       struct acpi_device *child;
>> +       struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cells;
>> +       int size, ret, count = 0, cell_num = 0;
>> +
>> +       range = kzalloc(sizeof(*range), GFP_KERNEL);
>> +       if (!range)
>> +               return -ENOMEM;
>> +       range->fwnode = &adev->fwnode;
>> +       range->flags = PIO_INDIRECT;
>> +       range->size = PIO_INDIRECT_SIZE;
>> +
>> +       ret = logic_pio_register_range(range);
>> +       if (ret)
>> +               goto free_range;
>> +
>> +       list_for_each_entry(child, &adev->children, node)
>> +               cell_num++;
>> +
>> +       /* allocate the mfd cell and companion acpi info, one per child */
>> +       size = sizeof(*mfd_cells) + sizeof(*acpi_indirect_io_mfd_cells);
>> +       mfd_cells = kcalloc(cell_num, size, GFP_KERNEL);
>> +       if (!mfd_cells) {
>> +               ret = -ENOMEM;
>> +               goto free_range;
>> +       }
>> +
>> +       acpi_indirect_io_mfd_cells = (struct acpi_indirect_io_mfd_cell *)
>> +                                       &mfd_cells[cell_num];
>> +       /* Only consider the children of the host */
>> +       list_for_each_entry(child, &adev->children, node) {
>> +               struct mfd_cell *mfd_cell = &mfd_cells[count];
>> +               struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cell =
>> +                                       &acpi_indirect_io_mfd_cells[count];
>> +               const struct mfd_cell_acpi_match *acpi_match =
>> +                                       &acpi_indirect_io_mfd_cell->acpi_match;
>> +               char *name = &acpi_indirect_io_mfd_cell[count].name[0];
>> +               char *pnpid = &acpi_indirect_io_mfd_cell[count].pnpid[0];
>> +               struct mfd_cell_acpi_match match = {
>> +                       .pnpid = pnpid,
>> +               };
>> +
>> +               snprintf(name, ACPI_INDIRECT_IO_NAME_LEN, "indirect-io-%s",
>> +                        acpi_device_hid(child));
>> +               snprintf(pnpid, ACPI_INDIRECT_IO_NAME_LEN, "%s",
>> +                        acpi_device_hid(child));
>> +
>> +               memcpy((void *)acpi_match, (void *)&match, sizeof(*acpi_match));
>> +               mfd_cell->name = name;
>> +               mfd_cell->acpi_match = acpi_match;
>> +
>> +               ret = acpi_indirect_io_set_res(&child->dev, &adev->dev,
>> +                                              &mfd_cell->resources,
>> +                                              &mfd_cell->num_resources);
>> +               if (ret) {
>> +                       dev_err(&child->dev, "set resource failed (%d)\n", ret);
>
> Again, please consider using dev_dbg() here and below (for the same
> reason as above).
>

well if this happens the device is not enumerated, so I think a warn may 
be more appropiate

>> +                       goto free_mfd_resources;
>> +               }
>> +               count++;
>> +       }
>> +
>> +       pdev = acpi_create_platform_device(adev, NULL);
>> +       if (IS_ERR_OR_NULL(pdev)) {
>> +               dev_err(&adev->dev, "create platform device for host failed\n");

as above

>> +               ret = PTR_ERR(pdev);
>> +               goto free_mfd_resources;
>> +       }
>> +       acpi_device_set_enumerated(adev);
>> +
>> +       ret = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
>> +                             mfd_cells, cell_num, NULL, 0, NULL);
>> +       if (ret) {
>> +               dev_err(&pdev->dev, "failed to add mfd cells (%d)\n", ret);
>> +               goto free_mfd_resources;
>> +       }
>> +
>> +       return ret;
>
> return 0;
>
> You know that ret must be 0 here anyway.

yes, I prefer this

>
>> +
>> +free_mfd_resources:
>> +       while (cell_num--)
>> +               kfree(mfd_cells[cell_num].resources);
>> +       kfree(mfd_cells);
>> +free_range:
>> +       kfree(range);
>> +
>> +       return ret;
>> +}
>> +
>> +/* All the host devices which apply indirect-IO can be listed here. */
>> +static const struct acpi_device_id acpi_indirect_io_host_id[] = {
>> +       {}
>> +};
>> +
>> +static int acpi_indirect_io_attach(struct acpi_device *adev,
>> +                                  const struct acpi_device_id *id)
>> +{
>> +       int ret = acpi_indirect_io_setup(adev);
>> +
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       return 1;
>
> The above can be written as
>
> return ret < 0 ? ret : 1;
>
> to save a few lines of code (you are using this pattern above, so why
> not here?).

I can change it.

>
>> +}
>> +
>> +static struct acpi_scan_handler acpi_indirect_io_handler = {
>> +       .ids = acpi_indirect_io_host_id,
>> +       .attach = acpi_indirect_io_attach,
>> +};
>> +
>> +void __init acpi_indirect_io_scan_init(void)
>> +{
>> +       acpi_scan_add_handler(&acpi_indirect_io_handler);
>> +}
>> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
>> index 1d0a501..680f3cf 100644
>> --- a/drivers/acpi/internal.h
>> +++ b/drivers/acpi/internal.h
>> @@ -31,6 +31,11 @@
>>  void acpi_platform_init(void);
>>  void acpi_pnp_init(void);
>>  void acpi_int340x_thermal_init(void);
>> +#ifdef CONFIG_INDIRECT_PIO
>> +void acpi_indirect_io_scan_init(void);
>> +#else
>> +static inline void acpi_indirect_io_scan_init(void) {}
>> +#endif
>>  #ifdef CONFIG_ARM_AMBA
>>  void acpi_amba_init(void);
>>  #else
>> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
>> index 8e63d93..204da8a 100644
>> --- a/drivers/acpi/scan.c
>> +++ b/drivers/acpi/scan.c
>> @@ -2155,6 +2155,7 @@ int __init acpi_scan_init(void)
>>         acpi_amba_init();
>>         acpi_watchdog_init();
>>         acpi_init_lpit();
>> +       acpi_indirect_io_scan_init();
>>
>>         acpi_scan_add_handler(&generic_device_handler);
>>
>> --
>
> But generally
>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> for the generic ACPI changes.
>

Thanks,
John

> .
>
Andy Shevchenko Feb. 14, 2018, 1:53 p.m. | #3
On Tue, Feb 13, 2018 at 7:45 PM, John Garry <john.garry@huawei.com> wrote:
> On some platforms (such as arm64-based hip06/hip07), access to legacy
> ISA/LPC devices through access IO space is required, similar to x86
> platforms. As the I/O for these devices are not memory mapped like
> PCI/PCIE MMIO host bridges, they require special low-level device
> operations through some host to generate IO accesses, i.e. a non-
> transparent bridge.
>
> Through the logical PIO framework, hosts are able to register address
> ranges in the logical PIO space for IO accesses. For hosts which require
> a LLDD to generate the IO accesses, through the logical PIO framework
> the host also registers accessors as a backend to generate the physical
> bus transactions for IO space accesses (called indirect IO).
>
> When describing the indirect IO child device in APCI tables, the IO
> resource is the host-specific address for the child (generally a
> bus address).
> An example is as follows:
>   Device (LPC0) {
>     Name (_HID, "HISI0191")  // HiSi LPC
>     Name (_CRS, ResourceTemplate () {
>       Memory32Fixed (ReadWrite, 0xa01b0000, 0x1000)
>     })
>   }
>
>   Device (LPC0.IPMI) {
>     Name (_HID, "IPI0001")
>     Name (LORS, ResourceTemplate() {
>       QWordIO (
>         ResourceConsumer,
>         MinNotFixed,     // _MIF
>         MaxNotFixed,     // _MAF
>         PosDecode,
>         EntireRange,
>         0x0,             // _GRA
>         0xe4,            // _MIN
>         0x3fff,          // _MAX
>         0x0,             // _TRA
>         0x04,            // _LEN
>         , ,
>         BTIO
>       )
>     })
>
> Since the IO resource for the child is a host-specific address,
> special translation are required to retrieve the logical PIO address
> for that child.
>
> To overcome the problem of associating this logical PIO address
> with the child device, a scan handler is added to scan the ACPI
> namespace for known indirect IO hosts. This scan handler creates an
> MFD per child with the translated logical PIO address as it's IO
> resource, as a substitute for the normal platform device which ACPI
> would create during device enumeration.

> +       unsigned long sys_port;

> +       sys_port = logic_pio_trans_hwaddr(&host->fwnode, res->start, len);
> +       if (sys_port == -1UL)

Wouldn't it be better to compare with ULONG_MAX?

> +               return -EFAULT;


> +/*

Shouldn't be a kernel-doc?

> + * acpi_indirect_io_set_res - set the resources for a child device
> + * (MFD) of an "indirect IO" host.

In that case this would be one line w/o period at the end.

> + * @child: the device node to be updated the I/O resource
> + * @hostdev: the device node associated with the "indirect IO" host
> + * @res: double pointer to be set to the address of translated resources
> + * @num_res: pointer to variable to hold the number of translated resources
> + *
> + * Returns 0 when successful, and a negative value for failure.
> + *
> + * For a given "indirect IO" host, each child device will have associated
> + * host-relevative address resource. This function will return the translated
> + * logical PIO addresses for each child devices resources.
> + */
> +static int acpi_indirect_io_set_res(struct device *child,
> +                                   struct device *hostdev,
> +                                   const struct resource **res,
> +                                   int *num_res)
> +{
> +       struct acpi_device *adev;
> +       struct acpi_device *host;
> +       struct resource_entry *rentry;
> +       LIST_HEAD(resource_list);
> +       struct resource *resources;
> +       int count;
> +       int i;
> +       int ret = -EIO;
> +
> +       if (!child || !hostdev)
> +               return -EINVAL;
> +
> +       host = to_acpi_device(hostdev);
> +       adev = to_acpi_device(child);

> +       count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
> +       if (count <= 0) {
> +               dev_err(child, "failed to get resources\n");
> +               return count ? count : -EIO;
> +       }
> +
> +       resources = kcalloc(count, sizeof(*resources), GFP_KERNEL);
> +       if (!resources) {
> +               acpi_dev_free_resource_list(&resource_list);
> +               return -ENOMEM;
> +       }
> +       count = 0;
> +       list_for_each_entry(rentry, &resource_list, node)
> +               resources[count++] = *rentry->res;
> +
> +       acpi_dev_free_resource_list(&resource_list);

It has similarities with acpi_create_platform_device().
I guess we can utilize existing code.

> +       /* translate the I/O resources */
> +       for (i = 0; i < count; i++) {
> +               if (!(resources[i].flags & IORESOURCE_IO))
> +                       continue;

> +               ret = acpi_indirect_io_xlat_res(adev, host, &resources[i]);
> +               if (ret) {
> +                       kfree(resources);
> +                       dev_err(child, "translate IO range failed(%d)\n", ret);
> +                       return ret;
> +               }
> +       }
> +       *res = resources;
> +       *num_res = count;
> +
> +       return ret;

Perhaps,

   ret = ...
   if (ret)
    break;
  }

  if (ret) {
                       kfree(resources);
                       dev_err(child, "translate IO range failed(%d)\n", ret);
                       return ret;
  }

  *res = resources;
  *num_res = count;
  return 0;

?

> +}
> +
> +/*
> + * acpi_indirect_io_setup - scan handler for "indirect IO" host.
> + * @adev: "indirect IO" host ACPI device pointer
> + * Returns 0 when successful, and a negative value for failure.
> + *
> + * Setup an "indirect IO" host by scanning all child devices, and
> + * create a per-device MFD with logical PIO translated IO resources.
> + */
> +static int acpi_indirect_io_setup(struct acpi_device *adev)
> +{
> +       struct platform_device *pdev;
> +       struct mfd_cell *mfd_cells;
> +       struct logic_pio_hwaddr *range;
> +       struct acpi_device *child;
> +       struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cells;
> +       int size, ret, count = 0, cell_num = 0;
> +
> +       range = kzalloc(sizeof(*range), GFP_KERNEL);
> +       if (!range)
> +               return -ENOMEM;
> +       range->fwnode = &adev->fwnode;
> +       range->flags = PIO_INDIRECT;
> +       range->size = PIO_INDIRECT_SIZE;
> +
> +       ret = logic_pio_register_range(range);
> +       if (ret)
> +               goto free_range;
> +
> +       list_for_each_entry(child, &adev->children, node)
> +               cell_num++;
> +
> +       /* allocate the mfd cell and companion acpi info, one per child */
> +       size = sizeof(*mfd_cells) + sizeof(*acpi_indirect_io_mfd_cells);
> +       mfd_cells = kcalloc(cell_num, size, GFP_KERNEL);
> +       if (!mfd_cells) {
> +               ret = -ENOMEM;
> +               goto free_range;
> +       }
> +
> +       acpi_indirect_io_mfd_cells = (struct acpi_indirect_io_mfd_cell *)
> +                                       &mfd_cells[cell_num];
> +       /* Only consider the children of the host */
> +       list_for_each_entry(child, &adev->children, node) {
> +               struct mfd_cell *mfd_cell = &mfd_cells[count];
> +               struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cell =
> +                                       &acpi_indirect_io_mfd_cells[count];
> +               const struct mfd_cell_acpi_match *acpi_match =
> +                                       &acpi_indirect_io_mfd_cell->acpi_match;

> +               char *name = &acpi_indirect_io_mfd_cell[count].name[0];
> +               char *pnpid = &acpi_indirect_io_mfd_cell[count].pnpid[0];

Plain x is equivalent to &x[0].

> +               struct mfd_cell_acpi_match match = {
> +                       .pnpid = pnpid,
> +               };
> +
> +               snprintf(name, ACPI_INDIRECT_IO_NAME_LEN, "indirect-io-%s",
> +                        acpi_device_hid(child));
> +               snprintf(pnpid, ACPI_INDIRECT_IO_NAME_LEN, "%s",
> +                        acpi_device_hid(child))

> +               memcpy((void *)acpi_match, (void *)&match, sizeof(*acpi_match));

Casting to void * is pointless. In both cases.

> +               mfd_cell->name = name;
> +               mfd_cell->acpi_match = acpi_match;
> +
> +               ret = acpi_indirect_io_set_res(&child->dev, &adev->dev,
> +                                              &mfd_cell->resources,
> +                                              &mfd_cell->num_resources);
> +               if (ret) {
> +                       dev_err(&child->dev, "set resource failed (%d)\n", ret);
> +                       goto free_mfd_resources;
> +               }
> +               count++;
> +       }
> +
> +       pdev = acpi_create_platform_device(adev, NULL);
> +       if (IS_ERR_OR_NULL(pdev)) {
> +               dev_err(&adev->dev, "create platform device for host failed\n");

> +               ret = PTR_ERR(pdev);

So, NULL case will return 0. Is it expected?

> +               goto free_mfd_resources;
> +       }
> +       acpi_device_set_enumerated(adev);
> +
> +       ret = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
> +                             mfd_cells, cell_num, NULL, 0, NULL);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to add mfd cells (%d)\n", ret);
> +               goto free_mfd_resources;
> +       }
> +
> +       return ret;
> +
> +free_mfd_resources:
> +       while (cell_num--)
> +               kfree(mfd_cells[cell_num].resources);
> +       kfree(mfd_cells);
> +free_range:
> +       kfree(range);
> +
> +       return ret;
> +}

One question, what a scope of use of this function? Is it ->probe() time?
If it's so, can we use devm_* variants?
John Garry Feb. 14, 2018, 3:33 p.m. | #4
On 14/02/2018 13:53, Andy Shevchenko wrote:
> On Tue, Feb 13, 2018 at 7:45 PM, John Garry <john.garry@huawei.com> wrote:
>> On some platforms (such as arm64-based hip06/hip07), access to legacy
>> ISA/LPC devices through access IO space is required, similar to x86
>> platforms. As the I/O for these devices are not memory mapped like
>> PCI/PCIE MMIO host bridges, they require special low-level device
>> operations through some host to generate IO accesses, i.e. a non-
>> transparent bridge.
>>
>> Through the logical PIO framework, hosts are able to register address
>> ranges in the logical PIO space for IO accesses. For hosts which require
>> a LLDD to generate the IO accesses, through the logical PIO framework
>> the host also registers accessors as a backend to generate the physical
>> bus transactions for IO space accesses (called indirect IO).
>>
>> When describing the indirect IO child device in APCI tables, the IO
>> resource is the host-specific address for the child (generally a
>> bus address).
>> An example is as follows:
>>   Device (LPC0) {
>>     Name (_HID, "HISI0191")  // HiSi LPC
>>     Name (_CRS, ResourceTemplate () {
>>       Memory32Fixed (ReadWrite, 0xa01b0000, 0x1000)
>>     })
>>   }
>>
>>   Device (LPC0.IPMI) {
>>     Name (_HID, "IPI0001")
>>     Name (LORS, ResourceTemplate() {
>>       QWordIO (
>>         ResourceConsumer,
>>         MinNotFixed,     // _MIF
>>         MaxNotFixed,     // _MAF
>>         PosDecode,
>>         EntireRange,
>>         0x0,             // _GRA
>>         0xe4,            // _MIN
>>         0x3fff,          // _MAX
>>         0x0,             // _TRA
>>         0x04,            // _LEN
>>         , ,
>>         BTIO
>>       )
>>     })
>>
>> Since the IO resource for the child is a host-specific address,
>> special translation are required to retrieve the logical PIO address
>> for that child.
>>
>> To overcome the problem of associating this logical PIO address
>> with the child device, a scan handler is added to scan the ACPI
>> namespace for known indirect IO hosts. This scan handler creates an
>> MFD per child with the translated logical PIO address as it's IO
>> resource, as a substitute for the normal platform device which ACPI
>> would create during device enumeration.
>

Hi Andy,

>> +       unsigned long sys_port;
>
>> +       sys_port = logic_pio_trans_hwaddr(&host->fwnode, res->start, len);
>> +       if (sys_port == -1UL)
>
> Wouldn't it be better to compare with ULONG_MAX?

Could do, being the same thing. Maybe people prefer -1UL as it saves 
having to figure out what ULONG_MAX is :)

>
>> +               return -EFAULT;
>
>
>> +/*
>
> Shouldn't be a kernel-doc?

Right, I'll make it /**

>
>> + * acpi_indirect_io_set_res - set the resources for a child device
>> + * (MFD) of an "indirect IO" host.
>
> In that case this would be one line w/o period at the end.
>
>> + * @child: the device node to be updated the I/O resource
>> + * @hostdev: the device node associated with the "indirect IO" host
>> + * @res: double pointer to be set to the address of translated resources
>> + * @num_res: pointer to variable to hold the number of translated resources
>> + *
>> + * Returns 0 when successful, and a negative value for failure.
>> + *
>> + * For a given "indirect IO" host, each child device will have associated
>> + * host-relevative address resource. This function will return the translated
>> + * logical PIO addresses for each child devices resources.
>> + */
>> +static int acpi_indirect_io_set_res(struct device *child,
>> +                                   struct device *hostdev,
>> +                                   const struct resource **res,
>> +                                   int *num_res)
>> +{
>> +       struct acpi_device *adev;
>> +       struct acpi_device *host;
>> +       struct resource_entry *rentry;
>> +       LIST_HEAD(resource_list);
>> +       struct resource *resources;
>> +       int count;
>> +       int i;
>> +       int ret = -EIO;
>> +
>> +       if (!child || !hostdev)
>> +               return -EINVAL;
>> +
>> +       host = to_acpi_device(hostdev);
>> +       adev = to_acpi_device(child);
>

***

>> +       count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
>> +       if (count <= 0) {
>> +               dev_err(child, "failed to get resources\n");
>> +               return count ? count : -EIO;
>> +       }
>> +
>> +       resources = kcalloc(count, sizeof(*resources), GFP_KERNEL);
>> +       if (!resources) {
>> +               acpi_dev_free_resource_list(&resource_list);
>> +               return -ENOMEM;
>> +       }
>> +       count = 0;
>> +       list_for_each_entry(rentry, &resource_list, node)
>> +               resources[count++] = *rentry->res;
>> +
>> +       acpi_dev_free_resource_list(&resource_list);
>
> It has similarities with acpi_create_platform_device().
> I guess we can utilize existing code.
>

For sure, this particular segment is effectively same as part of 
acpi_create_platform_device():

struct platform_device *acpi_create_platform_device(struct acpi_device 
*adev,
                     struct property_entry *properties)
{
     struct platform_device *pdev = NULL;
     struct platform_device_info pdevinfo;
     struct resource_entry *rentry;
     struct list_head resource_list;
     struct resource *resources = NULL;
     int count;

     /* If the ACPI node already has a physical device attached, skip it. */
     if (adev->physical_node_count)
         return NULL;

     if (!acpi_match_device_ids(adev, forbidden_id_list))
         return ERR_PTR(-EINVAL);

***>
     INIT_LIST_HEAD(&resource_list);
     count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
     if (count < 0) {
         return NULL;
     } else if (count > 0) {
         resources = kzalloc(count * sizeof(struct resource),
                     GFP_KERNEL);
         if (!resources) {
             dev_err(&adev->dev, "No memory for resources\n");
             acpi_dev_free_resource_list(&resource_list);
             return ERR_PTR(-ENOMEM);
         }
         count = 0;
         list_for_each_entry(rentry, &resource_list, node)
             acpi_platform_fill_resource(adev, rentry->res,
                             &resources[count++]);

         acpi_dev_free_resource_list(&resource_list);
     }
<****
     memset(&pdevinfo, 0, sizeof(pdevinfo));
     /*
      * If the ACPI node has a parent and that parent has a physical

So is your idea to refactor this common segment into a helper function?

>> +       /* translate the I/O resources */
>> +       for (i = 0; i < count; i++) {
>> +               if (!(resources[i].flags & IORESOURCE_IO))
>> +                       continue;
>
>> +               ret = acpi_indirect_io_xlat_res(adev, host, &resources[i]);
>> +               if (ret) {
>> +                       kfree(resources);
>> +                       dev_err(child, "translate IO range failed(%d)\n", ret);
>> +                       return ret;
>> +               }
>> +       }
>> +       *res = resources;
>> +       *num_res = count;
>> +
>> +       return ret;
>
> Perhaps,
>
>    ret = ...
>    if (ret)
>     break;
>   }
>
>   if (ret) {
>                        kfree(resources);
>                        dev_err(child, "translate IO range failed(%d)\n", ret);
>                        return ret;
>   }
>
>   *res = resources;
>   *num_res = count;
>   return 0;

seems fine

>
> ?
>
>> +}
>> +
>> +/*
>> + * acpi_indirect_io_setup - scan handler for "indirect IO" host.
>> + * @adev: "indirect IO" host ACPI device pointer
>> + * Returns 0 when successful, and a negative value for failure.
>> + *
>> + * Setup an "indirect IO" host by scanning all child devices, and
>> + * create a per-device MFD with logical PIO translated IO resources.
>> + */
>> +static int acpi_indirect_io_setup(struct acpi_device *adev)
>> +{
>> +       struct platform_device *pdev;
>> +       struct mfd_cell *mfd_cells;
>> +       struct logic_pio_hwaddr *range;
>> +       struct acpi_device *child;
>> +       struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cells;
>> +       int size, ret, count = 0, cell_num = 0;
>> +
>> +       range = kzalloc(sizeof(*range), GFP_KERNEL);
>> +       if (!range)
>> +               return -ENOMEM;
>> +       range->fwnode = &adev->fwnode;
>> +       range->flags = PIO_INDIRECT;
>> +       range->size = PIO_INDIRECT_SIZE;
>> +
>> +       ret = logic_pio_register_range(range);
>> +       if (ret)
>> +               goto free_range;
>> +
>> +       list_for_each_entry(child, &adev->children, node)
>> +               cell_num++;
>> +
>> +       /* allocate the mfd cell and companion acpi info, one per child */
>> +       size = sizeof(*mfd_cells) + sizeof(*acpi_indirect_io_mfd_cells);
>> +       mfd_cells = kcalloc(cell_num, size, GFP_KERNEL);
>> +       if (!mfd_cells) {
>> +               ret = -ENOMEM;
>> +               goto free_range;
>> +       }
>> +
>> +       acpi_indirect_io_mfd_cells = (struct acpi_indirect_io_mfd_cell *)
>> +                                       &mfd_cells[cell_num];
>> +       /* Only consider the children of the host */
>> +       list_for_each_entry(child, &adev->children, node) {
>> +               struct mfd_cell *mfd_cell = &mfd_cells[count];
>> +               struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cell =
>> +                                       &acpi_indirect_io_mfd_cells[count];
>> +               const struct mfd_cell_acpi_match *acpi_match =
>> +                                       &acpi_indirect_io_mfd_cell->acpi_match;
>
>> +               char *name = &acpi_indirect_io_mfd_cell[count].name[0];
>> +               char *pnpid = &acpi_indirect_io_mfd_cell[count].pnpid[0];
>
> Plain x is equivalent to &x[0].

Right, but I thought for arrays that we should use address of x rather 
than x itself, no?

>
>> +               struct mfd_cell_acpi_match match = {
>> +                       .pnpid = pnpid,
>> +               };
>> +
>> +               snprintf(name, ACPI_INDIRECT_IO_NAME_LEN, "indirect-io-%s",
>> +                        acpi_device_hid(child));
>> +               snprintf(pnpid, ACPI_INDIRECT_IO_NAME_LEN, "%s",
>> +                        acpi_device_hid(child))
>
>> +               memcpy((void *)acpi_match, (void *)&match, sizeof(*acpi_match));
>
> Casting to void * is pointless. In both cases.

I rechecked this. The casting to void * was there to mask another issue 
which I've now fixed.

>
>> +               mfd_cell->name = name;
>> +               mfd_cell->acpi_match = acpi_match;
>> +
>> +               ret = acpi_indirect_io_set_res(&child->dev, &adev->dev,
>> +                                              &mfd_cell->resources,
>> +                                              &mfd_cell->num_resources);
>> +               if (ret) {
>> +                       dev_err(&child->dev, "set resource failed (%d)\n", ret);
>> +                       goto free_mfd_resources;
>> +               }
>> +               count++;
>> +       }
>> +
>> +       pdev = acpi_create_platform_device(adev, NULL);
>> +       if (IS_ERR_OR_NULL(pdev)) {
>> +               dev_err(&adev->dev, "create platform device for host failed\n");
>
>> +               ret = PTR_ERR(pdev);
>
> So, NULL case will return 0. Is it expected?
>

Should error in that case also, so I'll change.

>> +               goto free_mfd_resources;
>> +       }
>> +       acpi_device_set_enumerated(adev);
>> +
>> +       ret = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
>> +                             mfd_cells, cell_num, NULL, 0, NULL);
>> +       if (ret) {
>> +               dev_err(&pdev->dev, "failed to add mfd cells (%d)\n", ret);
>> +               goto free_mfd_resources;
>> +       }
>> +
>> +       return ret;
>> +
>> +free_mfd_resources:
>> +       while (cell_num--)
>> +               kfree(mfd_cells[cell_num].resources);
>> +       kfree(mfd_cells);
>> +free_range:
>> +       kfree(range);
>> +
>> +       return ret;
>> +}
>
> One question, what a scope of use of this function? Is it ->probe() time?
> If it's so, can we use devm_* variants?

It is called from a scan handler, so prior to device probing.

>

Thanks,
John
Lorenzo Pieralisi Feb. 14, 2018, 4:16 p.m. | #5
On Wed, Feb 14, 2018 at 01:45:31AM +0800, John Garry wrote:
> On some platforms (such as arm64-based hip06/hip07), access to legacy
> ISA/LPC devices through access IO space is required, similar to x86
> platforms. As the I/O for these devices are not memory mapped like
> PCI/PCIE MMIO host bridges, they require special low-level device
> operations through some host to generate IO accesses, i.e. a non-
> transparent bridge.
> 
> Through the logical PIO framework, hosts are able to register address
> ranges in the logical PIO space for IO accesses. For hosts which require
> a LLDD to generate the IO accesses, through the logical PIO framework
> the host also registers accessors as a backend to generate the physical
> bus transactions for IO space accesses (called indirect IO).
> 
> When describing the indirect IO child device in APCI tables, the IO
> resource is the host-specific address for the child (generally a
> bus address).
> An example is as follows:
>   Device (LPC0) {
>     Name (_HID, "HISI0191")  // HiSi LPC
>     Name (_CRS, ResourceTemplate () {
>       Memory32Fixed (ReadWrite, 0xa01b0000, 0x1000)
>     })
>   }
> 
>   Device (LPC0.IPMI) {
>     Name (_HID, "IPI0001")
>     Name (LORS, ResourceTemplate() {
>       QWordIO (
>         ResourceConsumer,
> 	MinNotFixed,     // _MIF
> 	MaxNotFixed,     // _MAF
> 	PosDecode,
> 	EntireRange,
> 	0x0,             // _GRA
> 	0xe4,            // _MIN
> 	0x3fff,          // _MAX
> 	0x0,             // _TRA
> 	0x04,            // _LEN
> 	, ,
> 	BTIO
>       )
>     })
> 
> Since the IO resource for the child is a host-specific address,
> special translation are required to retrieve the logical PIO address
> for that child.

The problem I have with this patchset and with pretending that the ACPI
bits are generic is that the rules used to translate resources (I am
referring to LPC0.IPMI above) are documented _nowhere_ which means that
making this series generic code is just wishful thinking - there are no
bindings backing it, it will never ever be used on a platform different
from the one you are pushing this code for and I stated this already.

Reworded differently - this is a Hisilicon driver it is not generic ACPI
code; I can't see how it can be used on a multitude of platforms unless
you specify FW level bindings.

> To overcome the problem of associating this logical PIO address
> with the child device, a scan handler is added to scan the ACPI
> namespace for known indirect IO hosts. This scan handler creates an
> MFD per child with the translated logical PIO address as it's IO
> resource, as a substitute for the normal platform device which ACPI
> would create during device enumeration.
> 
> Signed-off-by: John Garry <john.garry@huawei.com>
> Signed-off-by: Zhichang Yuan <yuanzhichang@hisilicon.com>
> Signed-off-by: Gabriele Paoloni <gabriele.paoloni@huawei.com>
> ---
>  drivers/acpi/arm64/Makefile          |   1 +
>  drivers/acpi/arm64/acpi_indirectio.c | 250 +++++++++++++++++++++++++++++++++++

See above (and I do not understand what arm64 has to do with it).

I understand you need to find a place to add the:

acpi_indirect_io_scan_init()

to be called from core ACPI code because ACPI can't handle probe
dependencies in any other way but other than that this patch is
a Hisilicon ACPI driver - there is nothing generic in it (or at
least there are no standard bindings to make it so).

Whether a callback from ACPI core code (acpi_scan_init()) to a driver
specific hook is sane or not that's the question and the only reason
why you want to add this in drivers/acpi/arm64 rather than, say,
drivers/bus (as you do for the DT driver).

I do not know Rafael's opinion on the above, I would like to help
you make forward progress but please understand my concerns, mostly
on FW side.

Thanks,
Lorenzo

>  drivers/acpi/internal.h              |   5 +
>  drivers/acpi/scan.c                  |   1 +
>  4 files changed, 257 insertions(+)
>  create mode 100644 drivers/acpi/arm64/acpi_indirectio.c
> 
> diff --git a/drivers/acpi/arm64/Makefile b/drivers/acpi/arm64/Makefile
> index 1017def..f4a7f46 100644
> --- a/drivers/acpi/arm64/Makefile
> +++ b/drivers/acpi/arm64/Makefile
> @@ -1,2 +1,3 @@
>  obj-$(CONFIG_ACPI_IORT) 	+= iort.o
>  obj-$(CONFIG_ACPI_GTDT) 	+= gtdt.o
> +obj-$(CONFIG_INDIRECT_PIO)	+= acpi_indirectio.o
> diff --git a/drivers/acpi/arm64/acpi_indirectio.c b/drivers/acpi/arm64/acpi_indirectio.c
> new file mode 100644
> index 0000000..51a1b92
> --- /dev/null
> +++ b/drivers/acpi/arm64/acpi_indirectio.c
> @@ -0,0 +1,250 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2017 HiSilicon Limited, All Rights Reserved.
> + * Author: Gabriele Paoloni <gabriele.paoloni@huawei.com>
> + * Author: Zhichang Yuan <yuanzhichang@hisilicon.com>
> + * Author: John Garry <john.garry@huawei.com>
> + *
> + * This file implements functunality to scan the ACPI namespace and config
> + * devices under "indirect IO" hosts. An "indirect IO" host allows child
> + * devices to use logical IO accesses when the host, itself, does not provide
> + * a transparent bridge. The device setup creates a per-child MFD with a
> + * logical port IO resource.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/logic_pio.h>
> +#include <linux/mfd/core.h>
> +#include <linux/platform_device.h>
> +
> +ACPI_MODULE_NAME("indirect IO");
> +
> +#define ACPI_INDIRECT_IO_NAME_LEN 255
> +
> +struct acpi_indirect_io_mfd_cell {
> +	struct mfd_cell_acpi_match acpi_match;
> +	char name[ACPI_INDIRECT_IO_NAME_LEN];
> +	char pnpid[ACPI_INDIRECT_IO_NAME_LEN];
> +};
> +
> +static int acpi_indirect_io_xlat_res(struct acpi_device *adev,
> +				     struct acpi_device *host,
> +				     struct resource *res)
> +{
> +	unsigned long sys_port;
> +	resource_size_t len = res->end - res->start;
> +
> +	sys_port = logic_pio_trans_hwaddr(&host->fwnode, res->start, len);
> +	if (sys_port == -1UL)
> +		return -EFAULT;
> +
> +	res->start = sys_port;
> +	res->end = sys_port + len;
> +
> +	return 0;
> +}
> +
> +/*
> + * acpi_indirect_io_set_res - set the resources for a child device
> + * (MFD) of an "indirect IO" host.
> + * @child: the device node to be updated the I/O resource
> + * @hostdev: the device node associated with the "indirect IO" host
> + * @res: double pointer to be set to the address of translated resources
> + * @num_res: pointer to variable to hold the number of translated resources
> + *
> + * Returns 0 when successful, and a negative value for failure.
> + *
> + * For a given "indirect IO" host, each child device will have associated
> + * host-relevative address resource. This function will return the translated
> + * logical PIO addresses for each child devices resources.
> + */
> +static int acpi_indirect_io_set_res(struct device *child,
> +				    struct device *hostdev,
> +				    const struct resource **res,
> +				    int *num_res)
> +{
> +	struct acpi_device *adev;
> +	struct acpi_device *host;
> +	struct resource_entry *rentry;
> +	LIST_HEAD(resource_list);
> +	struct resource *resources;
> +	int count;
> +	int i;
> +	int ret = -EIO;
> +
> +	if (!child || !hostdev)
> +		return -EINVAL;
> +
> +	host = to_acpi_device(hostdev);
> +	adev = to_acpi_device(child);
> +
> +	/* check the device state */
> +	if (!adev->status.present) {
> +		dev_info(child, "device is not present\n");
> +		return 0;
> +	}
> +	/* whether the child had been enumerated? */
> +	if (acpi_device_enumerated(adev)) {
> +		dev_info(child, "had been enumerated\n");
> +		return 0;
> +	}
> +
> +	count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
> +	if (count <= 0) {
> +		dev_err(child, "failed to get resources\n");
> +		return count ? count : -EIO;
> +	}
> +
> +	resources = kcalloc(count, sizeof(*resources), GFP_KERNEL);
> +	if (!resources) {
> +		acpi_dev_free_resource_list(&resource_list);
> +		return -ENOMEM;
> +	}
> +	count = 0;
> +	list_for_each_entry(rentry, &resource_list, node)
> +		resources[count++] = *rentry->res;
> +
> +	acpi_dev_free_resource_list(&resource_list);
> +
> +	/* translate the I/O resources */
> +	for (i = 0; i < count; i++) {
> +		if (!(resources[i].flags & IORESOURCE_IO))
> +			continue;
> +		ret = acpi_indirect_io_xlat_res(adev, host, &resources[i]);
> +		if (ret) {
> +			kfree(resources);
> +			dev_err(child, "translate IO range failed(%d)\n", ret);
> +			return ret;
> +		}
> +	}
> +	*res = resources;
> +	*num_res = count;
> +
> +	return ret;
> +}
> +
> +/*
> + * acpi_indirect_io_setup - scan handler for "indirect IO" host.
> + * @adev: "indirect IO" host ACPI device pointer
> + * Returns 0 when successful, and a negative value for failure.
> + *
> + * Setup an "indirect IO" host by scanning all child devices, and
> + * create a per-device MFD with logical PIO translated IO resources.
> + */
> +static int acpi_indirect_io_setup(struct acpi_device *adev)
> +{
> +	struct platform_device *pdev;
> +	struct mfd_cell *mfd_cells;
> +	struct logic_pio_hwaddr *range;
> +	struct acpi_device *child;
> +	struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cells;
> +	int size, ret, count = 0, cell_num = 0;
> +
> +	range = kzalloc(sizeof(*range), GFP_KERNEL);
> +	if (!range)
> +		return -ENOMEM;
> +	range->fwnode = &adev->fwnode;
> +	range->flags = PIO_INDIRECT;
> +	range->size = PIO_INDIRECT_SIZE;
> +
> +	ret = logic_pio_register_range(range);
> +	if (ret)
> +		goto free_range;
> +
> +	list_for_each_entry(child, &adev->children, node)
> +		cell_num++;
> +
> +	/* allocate the mfd cell and companion acpi info, one per child */
> +	size = sizeof(*mfd_cells) + sizeof(*acpi_indirect_io_mfd_cells);
> +	mfd_cells = kcalloc(cell_num, size, GFP_KERNEL);
> +	if (!mfd_cells) {
> +		ret = -ENOMEM;
> +		goto free_range;
> +	}
> +
> +	acpi_indirect_io_mfd_cells = (struct acpi_indirect_io_mfd_cell *)
> +					&mfd_cells[cell_num];
> +	/* Only consider the children of the host */
> +	list_for_each_entry(child, &adev->children, node) {
> +		struct mfd_cell *mfd_cell = &mfd_cells[count];
> +		struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cell =
> +					&acpi_indirect_io_mfd_cells[count];
> +		const struct mfd_cell_acpi_match *acpi_match =
> +					&acpi_indirect_io_mfd_cell->acpi_match;
> +		char *name = &acpi_indirect_io_mfd_cell[count].name[0];
> +		char *pnpid = &acpi_indirect_io_mfd_cell[count].pnpid[0];
> +		struct mfd_cell_acpi_match match = {
> +			.pnpid = pnpid,
> +		};
> +
> +		snprintf(name, ACPI_INDIRECT_IO_NAME_LEN, "indirect-io-%s",
> +			 acpi_device_hid(child));
> +		snprintf(pnpid, ACPI_INDIRECT_IO_NAME_LEN, "%s",
> +			 acpi_device_hid(child));
> +
> +		memcpy((void *)acpi_match, (void *)&match, sizeof(*acpi_match));
> +		mfd_cell->name = name;
> +		mfd_cell->acpi_match = acpi_match;
> +
> +		ret = acpi_indirect_io_set_res(&child->dev, &adev->dev,
> +					       &mfd_cell->resources,
> +					       &mfd_cell->num_resources);
> +		if (ret) {
> +			dev_err(&child->dev, "set resource failed (%d)\n", ret);
> +			goto free_mfd_resources;
> +		}
> +		count++;
> +	}
> +
> +	pdev = acpi_create_platform_device(adev, NULL);
> +	if (IS_ERR_OR_NULL(pdev)) {
> +		dev_err(&adev->dev, "create platform device for host failed\n");
> +		ret = PTR_ERR(pdev);
> +		goto free_mfd_resources;
> +	}
> +	acpi_device_set_enumerated(adev);
> +
> +	ret = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
> +			      mfd_cells, cell_num, NULL, 0, NULL);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to add mfd cells (%d)\n", ret);
> +		goto free_mfd_resources;
> +	}
> +
> +	return ret;
> +
> +free_mfd_resources:
> +	while (cell_num--)
> +		kfree(mfd_cells[cell_num].resources);
> +	kfree(mfd_cells);
> +free_range:
> +	kfree(range);
> +
> +	return ret;
> +}
> +
> +/* All the host devices which apply indirect-IO can be listed here. */
> +static const struct acpi_device_id acpi_indirect_io_host_id[] = {
> +	{}
> +};
> +
> +static int acpi_indirect_io_attach(struct acpi_device *adev,
> +				   const struct acpi_device_id *id)
> +{
> +	int ret = acpi_indirect_io_setup(adev);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	return 1;
> +}
> +
> +static struct acpi_scan_handler acpi_indirect_io_handler = {
> +	.ids = acpi_indirect_io_host_id,
> +	.attach = acpi_indirect_io_attach,
> +};
> +
> +void __init acpi_indirect_io_scan_init(void)
> +{
> +	acpi_scan_add_handler(&acpi_indirect_io_handler);
> +}
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index 1d0a501..680f3cf 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -31,6 +31,11 @@
>  void acpi_platform_init(void);
>  void acpi_pnp_init(void);
>  void acpi_int340x_thermal_init(void);
> +#ifdef CONFIG_INDIRECT_PIO
> +void acpi_indirect_io_scan_init(void);
> +#else
> +static inline void acpi_indirect_io_scan_init(void) {}
> +#endif
>  #ifdef CONFIG_ARM_AMBA
>  void acpi_amba_init(void);
>  #else
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 8e63d93..204da8a 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -2155,6 +2155,7 @@ int __init acpi_scan_init(void)
>  	acpi_amba_init();
>  	acpi_watchdog_init();
>  	acpi_init_lpit();
> +	acpi_indirect_io_scan_init();
>  
>  	acpi_scan_add_handler(&generic_device_handler);
>  
> -- 
> 1.9.1
>
Andy Shevchenko Feb. 14, 2018, 4:16 p.m. | #6
On Wed, Feb 14, 2018 at 5:33 PM, John Garry <john.garry@huawei.com> wrote:
> On 14/02/2018 13:53, Andy Shevchenko wrote:
>> On Tue, Feb 13, 2018 at 7:45 PM, John Garry <john.garry@huawei.com> wrote:

>>> +       sys_port = logic_pio_trans_hwaddr(&host->fwnode, res->start,
>>> len);
>>> +       if (sys_port == -1UL)

>> Wouldn't it be better to compare with ULONG_MAX?

> Could do, being the same thing. Maybe people prefer -1UL as it saves having
> to figure out what ULONG_MAX is :)

-1UL looks confusing.

Another approach is to use ~0UL if that is preferable.

>>> +       list_for_each_entry(rentry, &resource_list, node)
>>> +               resources[count++] = *rentry->res;

>> It has similarities with acpi_create_platform_device().
>> I guess we can utilize existing code.

> For sure, this particular segment is effectively same as part of
> acpi_create_platform_device():

Not the same, acpi_create_platform_device() does a bit more than
copying the resources. If it indeed makes no hurt...

>         list_for_each_entry(rentry, &resource_list, node)
>             acpi_platform_fill_resource(adev, rentry->res,
>                             &resources[count++]);

> So is your idea to refactor this common segment into a helper function?

...I would go with helper.

>>> +               char *name = &acpi_indirect_io_mfd_cell[count].name[0];
>>> +               char *pnpid = &acpi_indirect_io_mfd_cell[count].pnpid[0];
>>
>>
>> Plain x is equivalent to &x[0].

> Right, but I thought for arrays that we should use address of x rather than
> x itself, no?

x is addressed by it's beginning.
John Garry Feb. 14, 2018, 4:52 p.m. | #7
On 14/02/2018 16:16, Lorenzo Pieralisi wrote:
> On Wed, Feb 14, 2018 at 01:45:31AM +0800, John Garry wrote:
>> On some platforms (such as arm64-based hip06/hip07), access to legacy
>> ISA/LPC devices through access IO space is required, similar to x86
>> platforms. As the I/O for these devices are not memory mapped like
>> PCI/PCIE MMIO host bridges, they require special low-level device
>> operations through some host to generate IO accesses, i.e. a non-
>> transparent bridge.
>>
>> Through the logical PIO framework, hosts are able to register address
>> ranges in the logical PIO space for IO accesses. For hosts which require
>> a LLDD to generate the IO accesses, through the logical PIO framework
>> the host also registers accessors as a backend to generate the physical
>> bus transactions for IO space accesses (called indirect IO).
>>
>> When describing the indirect IO child device in APCI tables, the IO
>> resource is the host-specific address for the child (generally a
>> bus address).
>> An example is as follows:
>>   Device (LPC0) {
>>     Name (_HID, "HISI0191")  // HiSi LPC
>>     Name (_CRS, ResourceTemplate () {
>>       Memory32Fixed (ReadWrite, 0xa01b0000, 0x1000)
>>     })
>>   }
>>
>>   Device (LPC0.IPMI) {
>>     Name (_HID, "IPI0001")
>>     Name (LORS, ResourceTemplate() {
>>       QWordIO (
>>         ResourceConsumer,
>> 	MinNotFixed,     // _MIF
>> 	MaxNotFixed,     // _MAF
>> 	PosDecode,
>> 	EntireRange,
>> 	0x0,             // _GRA
>> 	0xe4,            // _MIN
>> 	0x3fff,          // _MAX
>> 	0x0,             // _TRA
>> 	0x04,            // _LEN
>> 	, ,
>> 	BTIO
>>       )
>>     })
>>
>> Since the IO resource for the child is a host-specific address,
>> special translation are required to retrieve the logical PIO address
>> for that child.
>

Hi Lorenzo,

> The problem I have with this patchset and with pretending that the ACPI
> bits are generic is that the rules used to translate resources (I am
> referring to LPC0.IPMI above) are documented _nowhere_ which means that
> making this series generic code is just wishful thinking - there are no
> bindings backing it, it will never ever be used on a platform different
> from the one you are pushing this code for and I stated this already.
>

Right, it is working on the presumption that this is how all "indirectio 
IO" hosts and children should/would be described in DSDT.

> Reworded differently - this is a Hisilicon driver it is not generic ACPI
> code; I can't see how it can be used on a multitude of platforms unless
> you specify FW level bindings.
>
>> To overcome the problem of associating this logical PIO address
>> with the child device, a scan handler is added to scan the ACPI
>> namespace for known indirect IO hosts. This scan handler creates an
>> MFD per child with the translated logical PIO address as it's IO
>> resource, as a substitute for the normal platform device which ACPI
>> would create during device enumeration.
>>
>> Signed-off-by: John Garry <john.garry@huawei.com>
>> Signed-off-by: Zhichang Yuan <yuanzhichang@hisilicon.com>
>> Signed-off-by: Gabriele Paoloni <gabriele.paoloni@huawei.com>
>> ---
>>  drivers/acpi/arm64/Makefile          |   1 +
>>  drivers/acpi/arm64/acpi_indirectio.c | 250 +++++++++++++++++++++++++++++++++++
>
> See above (and I do not understand what arm64 has to do with it).

Nothing apart from only being used by arm64 platforms today, which is 
circumstantial.

>
> I understand you need to find a place to add the:
>
> acpi_indirect_io_scan_init()
>
> to be called from core ACPI code because ACPI can't handle probe
> dependencies in any other way but other than that this patch is
> a Hisilicon ACPI driver - there is nothing generic in it (or at
> least there are no standard bindings to make it so).
>
> Whether a callback from ACPI core code (acpi_scan_init()) to a driver
> specific hook is sane or not that's the question and the only reason
> why you want to add this in drivers/acpi/arm64 rather than, say,
> drivers/bus (as you do for the DT driver).
>
> I do not know Rafael's opinion on the above, I would like to help
> you make forward progress but please understand my concerns, mostly
> on FW side.
>

I did mention an alternative in my "ping" in v12 patch 7/9 (Feb 1), but 
no response to this specific note so I kept on the same path.

Here's what I then wrote:
"I think another solution - which you may prefer - is to avoid adding
this scan handler (and all this other scan code) and add a check like
acpi_is_serial_bus_slave() [which checks the device parent versus a list 
of known indirectIO hosts] to not enumerate these children, and do it 
from the LLDD host probe instead (https://lkml.org/lkml/2017/6/16/250)"

Please consider this.

> Thanks,
> Lorenzo
>
>>  drivers/acpi/internal.h              |   5 +
>>  drivers/acpi/scan.c                  |   1 +
>>  4 files changed, 257 insertions(+)
>>  create mode 100644 drivers/acpi/arm64/acpi_indirectio.c
>>

Cheers,
John
John Garry Feb. 15, 2018, 11:19 a.m. | #8
> Nothing apart from only being used by arm64 platforms today, which is
> circumstantial.
>
>>
>> I understand you need to find a place to add the:
>>
>> acpi_indirect_io_scan_init()
>>
>> to be called from core ACPI code because ACPI can't handle probe
>> dependencies in any other way but other than that this patch is
>> a Hisilicon ACPI driver - there is nothing generic in it (or at
>> least there are no standard bindings to make it so).
>>
>> Whether a callback from ACPI core code (acpi_scan_init()) to a driver
>> specific hook is sane or not that's the question and the only reason
>> why you want to add this in drivers/acpi/arm64 rather than, say,
>> drivers/bus (as you do for the DT driver).
>>
>> I do not know Rafael's opinion on the above, I would like to help
>> you make forward progress but please understand my concerns, mostly
>> on FW side.
>>
>
> I did mention an alternative in my "ping" in v12 patch 7/9 (Feb 1), but
> no response to this specific note so I kept on the same path.
>
> Here's what I then wrote:
> "I think another solution - which you may prefer - is to avoid adding
> this scan handler (and all this other scan code) and add a check like
> acpi_is_serial_bus_slave() [which checks the device parent versus a list
> of known indirectIO hosts] to not enumerate these children, and do it
> from the LLDD host probe instead (https://lkml.org/lkml/2017/6/16/250)"
>

Hi Rafael, Lorenzo,

I can avoid adding the scan handler in acpi_indirectio.c by skipping the 
child enumeration, like with this change in scan.c:

+static const struct acpi_device_id indirect_io_hosts[] = {
+    {"HISI0191", 0},    /* HiSilicon LPC host */
+    {},
+};
+
+static bool acpi_is_indirect_io_slave(struct acpi_device *device)
+{
+    struct acpi_device *parent = dev->parent;
+
+    if (!parent || acpi_match_device_ids(parent, indirect_io_hosts))
+        return false;
+
+    return true;
+}
+
  static bool acpi_is_serial_bus_slave(struct acpi_device *device)
  {
      struct list_head resource_list;
      bool is_serial_bus_slave = false;

+    if (acpi_is_indirect_io_slave(device))
+        return true;
+
      /* Macs use device properties in lieu of _CRS resources */


This means I can move all this scan code into the LLDD.

What do you think? Please let me know.

John
Rafael J. Wysocki Feb. 15, 2018, 11:47 a.m. | #9
On Thu, Feb 15, 2018 at 12:19 PM, John Garry <john.garry@huawei.com> wrote:
>> Nothing apart from only being used by arm64 platforms today, which is
>> circumstantial.
>>
>>>
>>> I understand you need to find a place to add the:
>>>
>>> acpi_indirect_io_scan_init()
>>>
>>> to be called from core ACPI code because ACPI can't handle probe
>>> dependencies in any other way but other than that this patch is
>>> a Hisilicon ACPI driver - there is nothing generic in it (or at
>>> least there are no standard bindings to make it so).
>>>
>>> Whether a callback from ACPI core code (acpi_scan_init()) to a driver
>>> specific hook is sane or not that's the question and the only reason
>>> why you want to add this in drivers/acpi/arm64 rather than, say,
>>> drivers/bus (as you do for the DT driver).
>>>
>>> I do not know Rafael's opinion on the above, I would like to help
>>> you make forward progress but please understand my concerns, mostly
>>> on FW side.
>>>
>>
>> I did mention an alternative in my "ping" in v12 patch 7/9 (Feb 1), but
>> no response to this specific note so I kept on the same path.
>>
>> Here's what I then wrote:
>> "I think another solution - which you may prefer - is to avoid adding
>> this scan handler (and all this other scan code) and add a check like
>> acpi_is_serial_bus_slave() [which checks the device parent versus a list
>> of known indirectIO hosts] to not enumerate these children, and do it
>> from the LLDD host probe instead (https://lkml.org/lkml/2017/6/16/250)"
>>
>
> Hi Rafael, Lorenzo,
>
> I can avoid adding the scan handler in acpi_indirectio.c by skipping the
> child enumeration, like with this change in scan.c:
>
> +static const struct acpi_device_id indirect_io_hosts[] = {
> +    {"HISI0191", 0},    /* HiSilicon LPC host */
> +    {},
> +};
> +
> +static bool acpi_is_indirect_io_slave(struct acpi_device *device)
> +{

Why don't you put the table definition here?

> +    struct acpi_device *parent = dev->parent;
> +
> +    if (!parent || acpi_match_device_ids(parent, indirect_io_hosts))
> +        return false;
> +
> +    return true;

return parent && !acpi_match_device_ids(parent, indirect_io_hosts);

> +}
> +
>  static bool acpi_is_serial_bus_slave(struct acpi_device *device)
>  {
>      struct list_head resource_list;
>      bool is_serial_bus_slave = false;
>
> +    if (acpi_is_indirect_io_slave(device))
> +        return true;
> +
>      /* Macs use device properties in lieu of _CRS resources */
>
>
> This means I can move all this scan code into the LLDD.
>
> What do you think? Please let me know.

If Lorenzo agrees, that will be fine by me modulo the above remarks.
Andy Shevchenko Feb. 15, 2018, 12:22 p.m. | #10
On Thu, Feb 15, 2018 at 1:19 PM, John Garry <john.garry@huawei.com> wrote:

> +static const struct acpi_device_id indirect_io_hosts[] = {
> +    {"HISI0191", 0},    /* HiSilicon LPC host */
> +    {},

Just a nit.

It seems lately this happens more often than usual, I mean a comma in
the terminator line.

If we remove it. we terminate not only at runtime, but at compile
time, which is slightly better.

> +};
Lorenzo Pieralisi Feb. 15, 2018, 12:36 p.m. | #11
On Thu, Feb 15, 2018 at 12:47:25PM +0100, Rafael J. Wysocki wrote:
> On Thu, Feb 15, 2018 at 12:19 PM, John Garry <john.garry@huawei.com> wrote:
> >> Nothing apart from only being used by arm64 platforms today, which is
> >> circumstantial.
> >>
> >>>
> >>> I understand you need to find a place to add the:
> >>>
> >>> acpi_indirect_io_scan_init()
> >>>
> >>> to be called from core ACPI code because ACPI can't handle probe
> >>> dependencies in any other way but other than that this patch is
> >>> a Hisilicon ACPI driver - there is nothing generic in it (or at
> >>> least there are no standard bindings to make it so).
> >>>
> >>> Whether a callback from ACPI core code (acpi_scan_init()) to a driver
> >>> specific hook is sane or not that's the question and the only reason
> >>> why you want to add this in drivers/acpi/arm64 rather than, say,
> >>> drivers/bus (as you do for the DT driver).
> >>>
> >>> I do not know Rafael's opinion on the above, I would like to help
> >>> you make forward progress but please understand my concerns, mostly
> >>> on FW side.
> >>>
> >>
> >> I did mention an alternative in my "ping" in v12 patch 7/9 (Feb 1), but
> >> no response to this specific note so I kept on the same path.
> >>
> >> Here's what I then wrote:
> >> "I think another solution - which you may prefer - is to avoid adding
> >> this scan handler (and all this other scan code) and add a check like
> >> acpi_is_serial_bus_slave() [which checks the device parent versus a list
> >> of known indirectIO hosts] to not enumerate these children, and do it
> >> from the LLDD host probe instead (https://lkml.org/lkml/2017/6/16/250)"
> >>
> >
> > Hi Rafael, Lorenzo,
> >
> > I can avoid adding the scan handler in acpi_indirectio.c by skipping the
> > child enumeration, like with this change in scan.c:
> >
> > +static const struct acpi_device_id indirect_io_hosts[] = {
> > +    {"HISI0191", 0},    /* HiSilicon LPC host */
> > +    {},
> > +};
> > +
> > +static bool acpi_is_indirect_io_slave(struct acpi_device *device)
> > +{
> 
> Why don't you put the table definition here?
> 
> > +    struct acpi_device *parent = dev->parent;
> > +
> > +    if (!parent || acpi_match_device_ids(parent, indirect_io_hosts))
> > +        return false;
> > +
> > +    return true;
> 
> return parent && !acpi_match_device_ids(parent, indirect_io_hosts);
> 
> > +}
> > +
> >  static bool acpi_is_serial_bus_slave(struct acpi_device *device)
> >  {
> >      struct list_head resource_list;
> >      bool is_serial_bus_slave = false;
> >
> > +    if (acpi_is_indirect_io_slave(device))
> > +        return true;
> > +
> >      /* Macs use device properties in lieu of _CRS resources */
> >
> >
> > This means I can move all this scan code into the LLDD.
> >
> > What do you think? Please let me know.
> 
> If Lorenzo agrees, that will be fine by me modulo the above remarks.

I agree and I thank you for accepting this in core ACPI code, I think
that's much cleaner than a driver specific scan hook.

It is a shame we do not have a generic identifier for such bus in ACPI
but that won't happen overnight anyway (if ever, I think a binding for
LPC in the ACPI specs is hard to justify).

Thank you,
Lorenzo
John Garry Feb. 15, 2018, 12:52 p.m. | #12
On 15/02/2018 12:22, Andy Shevchenko wrote:
> On Thu, Feb 15, 2018 at 1:19 PM, John Garry <john.garry@huawei.com> wrote:
>

Hi Andy,

>> +static const struct acpi_device_id indirect_io_hosts[] = {
>> +    {"HISI0191", 0},    /* HiSilicon LPC host */
>> +    {},
>
> Just a nit.
>

I noticed that I have this in the LLDD also. I think that this may be a 
force of habit.

> It seems lately this happens more often than usual, I mean a comma in
> the terminator line.
>
> If we remove it. we terminate not only at runtime, but at compile
> time, which is slightly better.

I grepped for "{}," in the drivers folder and it gives many results (I 
do accept that some are not sentinels):
 >grep -R "{}," * | tail
watchdog/gef_wdt.c:    {},
watchdog/asm9260_wdt.c:    {},
watchdog/bcm2835_wdt.c:    {},
watchdog/digicolor_wdt.c:    {},
watchdog/bcm7038_wdt.c:    {},
watchdog/ath79_wdt.c:    {},
watchdog/riowd.c:    {},
watchdog/sbsa_gwdt.c:    {},
watchdog/sbsa_gwdt.c:    {},
watchdog/bcm_kona_wdt.c:    {},

Much appreciated,
John
Andy Shevchenko Feb. 15, 2018, 12:55 p.m. | #13
On Thu, Feb 15, 2018 at 2:52 PM, John Garry <john.garry@huawei.com> wrote:
> On 15/02/2018 12:22, Andy Shevchenko wrote:
>> On Thu, Feb 15, 2018 at 1:19 PM, John Garry <john.garry@huawei.com> wrote:

>>> +static const struct acpi_device_id indirect_io_hosts[] = {
>>> +    {"HISI0191", 0},    /* HiSilicon LPC host */
>>> +    {},
>>
>>
>> Just a nit.
>>
>
> I noticed that I have this in the LLDD also. I think that this may be a
> force of habit.


>> It seems lately this happens more often than usual, I mean a comma in
>> the terminator line.
>>
>> If we remove it. we terminate not only at runtime, but at compile
>> time, which is slightly better.
>
>
> I grepped for "{}," in the drivers folder and it gives many results (I do
> accept that some are not sentinels):

Yes, in old code it might be, but why to cargo-culting bad (okay, less
worth) practices?

>>grep -R "{}," * | tail

Btw, `git grep ...` is much faster.

> watchdog/gef_wdt.c:    {},
> watchdog/asm9260_wdt.c:    {},
> watchdog/bcm2835_wdt.c:    {},
> watchdog/digicolor_wdt.c:    {},
> watchdog/bcm7038_wdt.c:    {},
> watchdog/ath79_wdt.c:    {},
> watchdog/riowd.c:    {},
> watchdog/sbsa_gwdt.c:    {},
> watchdog/sbsa_gwdt.c:    {},
> watchdog/bcm_kona_wdt.c:    {},
John Garry Feb. 15, 2018, 12:59 p.m. | #14
On 15/02/2018 11:47, Rafael J. Wysocki wrote:
> On Thu, Feb 15, 2018 at 12:19 PM, John Garry <john.garry@huawei.com> wrote:
>>> Nothing apart from only being used by arm64 platforms today, which is
>>> circumstantial.
>>>
>>>>
>>>> I understand you need to find a place to add the:
>>>>
>>>> acpi_indirect_io_scan_init()
>>>>
>>>> to be called from core ACPI code because ACPI can't handle probe
>>>> dependencies in any other way but other than that this patch is
>>>> a Hisilicon ACPI driver - there is nothing generic in it (or at
>>>> least there are no standard bindings to make it so).
>>>>
>>>> Whether a callback from ACPI core code (acpi_scan_init()) to a driver
>>>> specific hook is sane or not that's the question and the only reason
>>>> why you want to add this in drivers/acpi/arm64 rather than, say,
>>>> drivers/bus (as you do for the DT driver).
>>>>
>>>> I do not know Rafael's opinion on the above, I would like to help
>>>> you make forward progress but please understand my concerns, mostly
>>>> on FW side.
>>>>
>>>
>>> I did mention an alternative in my "ping" in v12 patch 7/9 (Feb 1), but
>>> no response to this specific note so I kept on the same path.
>>>
>>> Here's what I then wrote:
>>> "I think another solution - which you may prefer - is to avoid adding
>>> this scan handler (and all this other scan code) and add a check like
>>> acpi_is_serial_bus_slave() [which checks the device parent versus a list
>>> of known indirectIO hosts] to not enumerate these children, and do it
>>> from the LLDD host probe instead (https://lkml.org/lkml/2017/6/16/250)"
>>>
>>
>> Hi Rafael, Lorenzo,
>>
>> I can avoid adding the scan handler in acpi_indirectio.c by skipping the
>> child enumeration, like with this change in scan.c:
>>

Hi Rafael,

>> +static const struct acpi_device_id indirect_io_hosts[] = {
>> +    {"HISI0191", 0},    /* HiSilicon LPC host */
>> +    {},
>> +};
>> +
>> +static bool acpi_is_indirect_io_slave(struct acpi_device *device)
>> +{
>
> Why don't you put the table definition here?
>

I can do.

>> +    struct acpi_device *parent = dev->parent;
>> +
>> +    if (!parent || acpi_match_device_ids(parent, indirect_io_hosts))
>> +        return false;
>> +
>> +    return true;
>
> return parent && !acpi_match_device_ids(parent, indirect_io_hosts);

Fine, a bit more concise

>
>> +}
>> +
>>  static bool acpi_is_serial_bus_slave(struct acpi_device *device)
>>  {
>>      struct list_head resource_list;
>>      bool is_serial_bus_slave = false;
>>
>> +    if (acpi_is_indirect_io_slave(device))
>> +        return true;
>> +
>>      /* Macs use device properties in lieu of _CRS resources */
>>
>>
>> This means I can move all this scan code into the LLDD.
>>
>> What do you think? Please let me know.
>
> If Lorenzo agrees, that will be fine by me modulo the above remarks.
>
> .

I see Lorenzo also finds this ok, so I'll go with that.

Thanks to all,
John

>
John Garry Feb. 15, 2018, 5:07 p.m. | #15
On 14/02/2018 16:16, Andy Shevchenko wrote:
> Another approach is to use ~0UL if that is preferable.
>
>>>> >>> +       list_for_each_entry(rentry, &resource_list, node)
>>>> >>> +               resources[count++] = *rentry->res;
>>> >> It has similarities with acpi_create_platform_device().
>>> >> I guess we can utilize existing code.
>> > For sure, this particular segment is effectively same as part of
>> > acpi_create_platform_device():
> Not the same, acpi_create_platform_device() does a bit more than
> copying the resources. If it indeed makes no hurt...
>
>> >         list_for_each_entry(rentry, &resource_list, node)
>> >             acpi_platform_fill_resource(adev, rentry->res,
>> >                             &resources[count++]);
>> > So is your idea to refactor this common segment into a helper function?
> ...I would go with helper.
>

Hi Andy,

Since the plan now is that this code is no longer going to be added to 
drivers/acpi, but instead pushed to the LLDD, I am pondering whether we 
should still factor out of this common code. Opinion?

Thanks,
John

>>>> >>> +               char *name = &acpi_indirect_io_mfd_cell[count].name[0];
Andy Shevchenko Feb. 16, 2018, 2:42 p.m. | #16
On Thu, Feb 15, 2018 at 7:07 PM, John Garry <john.garry@huawei.com> wrote:
> On 14/02/2018 16:16, Andy Shevchenko wrote:

>>>>> >>> +       list_for_each_entry(rentry, &resource_list, node)
>>>>> >>> +               resources[count++] = *rentry->res;
>>>>
>>>> >> It has similarities with acpi_create_platform_device().
>>>> >> I guess we can utilize existing code.
>>>
>>> > For sure, this particular segment is effectively same as part of
>>> > acpi_create_platform_device():
>>
>> Not the same, acpi_create_platform_device() does a bit more than
>> copying the resources. If it indeed makes no hurt...
>>
>>> >         list_for_each_entry(rentry, &resource_list, node)
>>> >             acpi_platform_fill_resource(adev, rentry->res,
>>> >                             &resources[count++]);
>>> > So is your idea to refactor this common segment into a helper function?
>>
>> ...I would go with helper.
>>
>
> Hi Andy,
>
> Since the plan now is that this code is no longer going to be added to
> drivers/acpi, but instead pushed to the LLDD, I am pondering whether we
> should still factor out of this common code. Opinion?

I would still go with a common helper. Though, as first step, we can
make it lazy, i.e. put a comment in your code, like a todo notice (w/o
TODO word :-) ) to consider a common helper.
John Garry Feb. 16, 2018, 2:48 p.m. | #17
On 16/02/2018 14:42, Andy Shevchenko wrote:
> On Thu, Feb 15, 2018 at 7:07 PM, John Garry <john.garry@huawei.com> wrote:
>> On 14/02/2018 16:16, Andy Shevchenko wrote:
>
>>>>>>>>> +       list_for_each_entry(rentry, &resource_list, node)
>>>>>>>>> +               resources[count++] = *rentry->res;
>>>>>
>>>>>>> It has similarities with acpi_create_platform_device().
>>>>>>> I guess we can utilize existing code.
>>>>
>>>>> For sure, this particular segment is effectively same as part of
>>>>> acpi_create_platform_device():
>>>
>>> Not the same, acpi_create_platform_device() does a bit more than
>>> copying the resources. If it indeed makes no hurt...
>>>
>>>>>         list_for_each_entry(rentry, &resource_list, node)
>>>>>             acpi_platform_fill_resource(adev, rentry->res,
>>>>>                             &resources[count++]);
>>>>> So is your idea to refactor this common segment into a helper function?
>>>
>>> ...I would go with helper.
>>>
>>
>> Hi Andy,
>>
>> Since the plan now is that this code is no longer going to be added to
>> drivers/acpi, but instead pushed to the LLDD, I am pondering whether we
>> should still factor out of this common code. Opinion?
>
> I would still go with a common helper. Though, as first step, we can
> make it lazy, i.e. put a comment in your code, like a todo notice (w/o
> TODO word :-) ) to consider a common helper.

Fine, I was also thinking that I don't want to do this now as it could 
make merging the patchset more complex. For now, the ACPI change I plan 
creates no dependencies.

Cheers,
John

>

Patch

diff --git a/drivers/acpi/arm64/Makefile b/drivers/acpi/arm64/Makefile
index 1017def..f4a7f46 100644
--- a/drivers/acpi/arm64/Makefile
+++ b/drivers/acpi/arm64/Makefile
@@ -1,2 +1,3 @@ 
 obj-$(CONFIG_ACPI_IORT) 	+= iort.o
 obj-$(CONFIG_ACPI_GTDT) 	+= gtdt.o
+obj-$(CONFIG_INDIRECT_PIO)	+= acpi_indirectio.o
diff --git a/drivers/acpi/arm64/acpi_indirectio.c b/drivers/acpi/arm64/acpi_indirectio.c
new file mode 100644
index 0000000..51a1b92
--- /dev/null
+++ b/drivers/acpi/arm64/acpi_indirectio.c
@@ -0,0 +1,250 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2017 HiSilicon Limited, All Rights Reserved.
+ * Author: Gabriele Paoloni <gabriele.paoloni@huawei.com>
+ * Author: Zhichang Yuan <yuanzhichang@hisilicon.com>
+ * Author: John Garry <john.garry@huawei.com>
+ *
+ * This file implements functunality to scan the ACPI namespace and config
+ * devices under "indirect IO" hosts. An "indirect IO" host allows child
+ * devices to use logical IO accesses when the host, itself, does not provide
+ * a transparent bridge. The device setup creates a per-child MFD with a
+ * logical port IO resource.
+ */
+
+#include <linux/acpi.h>
+#include <linux/logic_pio.h>
+#include <linux/mfd/core.h>
+#include <linux/platform_device.h>
+
+ACPI_MODULE_NAME("indirect IO");
+
+#define ACPI_INDIRECT_IO_NAME_LEN 255
+
+struct acpi_indirect_io_mfd_cell {
+	struct mfd_cell_acpi_match acpi_match;
+	char name[ACPI_INDIRECT_IO_NAME_LEN];
+	char pnpid[ACPI_INDIRECT_IO_NAME_LEN];
+};
+
+static int acpi_indirect_io_xlat_res(struct acpi_device *adev,
+				     struct acpi_device *host,
+				     struct resource *res)
+{
+	unsigned long sys_port;
+	resource_size_t len = res->end - res->start;
+
+	sys_port = logic_pio_trans_hwaddr(&host->fwnode, res->start, len);
+	if (sys_port == -1UL)
+		return -EFAULT;
+
+	res->start = sys_port;
+	res->end = sys_port + len;
+
+	return 0;
+}
+
+/*
+ * acpi_indirect_io_set_res - set the resources for a child device
+ * (MFD) of an "indirect IO" host.
+ * @child: the device node to be updated the I/O resource
+ * @hostdev: the device node associated with the "indirect IO" host
+ * @res: double pointer to be set to the address of translated resources
+ * @num_res: pointer to variable to hold the number of translated resources
+ *
+ * Returns 0 when successful, and a negative value for failure.
+ *
+ * For a given "indirect IO" host, each child device will have associated
+ * host-relevative address resource. This function will return the translated
+ * logical PIO addresses for each child devices resources.
+ */
+static int acpi_indirect_io_set_res(struct device *child,
+				    struct device *hostdev,
+				    const struct resource **res,
+				    int *num_res)
+{
+	struct acpi_device *adev;
+	struct acpi_device *host;
+	struct resource_entry *rentry;
+	LIST_HEAD(resource_list);
+	struct resource *resources;
+	int count;
+	int i;
+	int ret = -EIO;
+
+	if (!child || !hostdev)
+		return -EINVAL;
+
+	host = to_acpi_device(hostdev);
+	adev = to_acpi_device(child);
+
+	/* check the device state */
+	if (!adev->status.present) {
+		dev_info(child, "device is not present\n");
+		return 0;
+	}
+	/* whether the child had been enumerated? */
+	if (acpi_device_enumerated(adev)) {
+		dev_info(child, "had been enumerated\n");
+		return 0;
+	}
+
+	count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
+	if (count <= 0) {
+		dev_err(child, "failed to get resources\n");
+		return count ? count : -EIO;
+	}
+
+	resources = kcalloc(count, sizeof(*resources), GFP_KERNEL);
+	if (!resources) {
+		acpi_dev_free_resource_list(&resource_list);
+		return -ENOMEM;
+	}
+	count = 0;
+	list_for_each_entry(rentry, &resource_list, node)
+		resources[count++] = *rentry->res;
+
+	acpi_dev_free_resource_list(&resource_list);
+
+	/* translate the I/O resources */
+	for (i = 0; i < count; i++) {
+		if (!(resources[i].flags & IORESOURCE_IO))
+			continue;
+		ret = acpi_indirect_io_xlat_res(adev, host, &resources[i]);
+		if (ret) {
+			kfree(resources);
+			dev_err(child, "translate IO range failed(%d)\n", ret);
+			return ret;
+		}
+	}
+	*res = resources;
+	*num_res = count;
+
+	return ret;
+}
+
+/*
+ * acpi_indirect_io_setup - scan handler for "indirect IO" host.
+ * @adev: "indirect IO" host ACPI device pointer
+ * Returns 0 when successful, and a negative value for failure.
+ *
+ * Setup an "indirect IO" host by scanning all child devices, and
+ * create a per-device MFD with logical PIO translated IO resources.
+ */
+static int acpi_indirect_io_setup(struct acpi_device *adev)
+{
+	struct platform_device *pdev;
+	struct mfd_cell *mfd_cells;
+	struct logic_pio_hwaddr *range;
+	struct acpi_device *child;
+	struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cells;
+	int size, ret, count = 0, cell_num = 0;
+
+	range = kzalloc(sizeof(*range), GFP_KERNEL);
+	if (!range)
+		return -ENOMEM;
+	range->fwnode = &adev->fwnode;
+	range->flags = PIO_INDIRECT;
+	range->size = PIO_INDIRECT_SIZE;
+
+	ret = logic_pio_register_range(range);
+	if (ret)
+		goto free_range;
+
+	list_for_each_entry(child, &adev->children, node)
+		cell_num++;
+
+	/* allocate the mfd cell and companion acpi info, one per child */
+	size = sizeof(*mfd_cells) + sizeof(*acpi_indirect_io_mfd_cells);
+	mfd_cells = kcalloc(cell_num, size, GFP_KERNEL);
+	if (!mfd_cells) {
+		ret = -ENOMEM;
+		goto free_range;
+	}
+
+	acpi_indirect_io_mfd_cells = (struct acpi_indirect_io_mfd_cell *)
+					&mfd_cells[cell_num];
+	/* Only consider the children of the host */
+	list_for_each_entry(child, &adev->children, node) {
+		struct mfd_cell *mfd_cell = &mfd_cells[count];
+		struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cell =
+					&acpi_indirect_io_mfd_cells[count];
+		const struct mfd_cell_acpi_match *acpi_match =
+					&acpi_indirect_io_mfd_cell->acpi_match;
+		char *name = &acpi_indirect_io_mfd_cell[count].name[0];
+		char *pnpid = &acpi_indirect_io_mfd_cell[count].pnpid[0];
+		struct mfd_cell_acpi_match match = {
+			.pnpid = pnpid,
+		};
+
+		snprintf(name, ACPI_INDIRECT_IO_NAME_LEN, "indirect-io-%s",
+			 acpi_device_hid(child));
+		snprintf(pnpid, ACPI_INDIRECT_IO_NAME_LEN, "%s",
+			 acpi_device_hid(child));
+
+		memcpy((void *)acpi_match, (void *)&match, sizeof(*acpi_match));
+		mfd_cell->name = name;
+		mfd_cell->acpi_match = acpi_match;
+
+		ret = acpi_indirect_io_set_res(&child->dev, &adev->dev,
+					       &mfd_cell->resources,
+					       &mfd_cell->num_resources);
+		if (ret) {
+			dev_err(&child->dev, "set resource failed (%d)\n", ret);
+			goto free_mfd_resources;
+		}
+		count++;
+	}
+
+	pdev = acpi_create_platform_device(adev, NULL);
+	if (IS_ERR_OR_NULL(pdev)) {
+		dev_err(&adev->dev, "create platform device for host failed\n");
+		ret = PTR_ERR(pdev);
+		goto free_mfd_resources;
+	}
+	acpi_device_set_enumerated(adev);
+
+	ret = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
+			      mfd_cells, cell_num, NULL, 0, NULL);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to add mfd cells (%d)\n", ret);
+		goto free_mfd_resources;
+	}
+
+	return ret;
+
+free_mfd_resources:
+	while (cell_num--)
+		kfree(mfd_cells[cell_num].resources);
+	kfree(mfd_cells);
+free_range:
+	kfree(range);
+
+	return ret;
+}
+
+/* All the host devices which apply indirect-IO can be listed here. */
+static const struct acpi_device_id acpi_indirect_io_host_id[] = {
+	{}
+};
+
+static int acpi_indirect_io_attach(struct acpi_device *adev,
+				   const struct acpi_device_id *id)
+{
+	int ret = acpi_indirect_io_setup(adev);
+
+	if (ret < 0)
+		return ret;
+
+	return 1;
+}
+
+static struct acpi_scan_handler acpi_indirect_io_handler = {
+	.ids = acpi_indirect_io_host_id,
+	.attach = acpi_indirect_io_attach,
+};
+
+void __init acpi_indirect_io_scan_init(void)
+{
+	acpi_scan_add_handler(&acpi_indirect_io_handler);
+}
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 1d0a501..680f3cf 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -31,6 +31,11 @@ 
 void acpi_platform_init(void);
 void acpi_pnp_init(void);
 void acpi_int340x_thermal_init(void);
+#ifdef CONFIG_INDIRECT_PIO
+void acpi_indirect_io_scan_init(void);
+#else
+static inline void acpi_indirect_io_scan_init(void) {}
+#endif
 #ifdef CONFIG_ARM_AMBA
 void acpi_amba_init(void);
 #else
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 8e63d93..204da8a 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2155,6 +2155,7 @@  int __init acpi_scan_init(void)
 	acpi_amba_init();
 	acpi_watchdog_init();
 	acpi_init_lpit();
+	acpi_indirect_io_scan_init();
 
 	acpi_scan_add_handler(&generic_device_handler);