[U-Boot,v1,1/4] drivers: Add a new framework for multiplexer devices
diff mbox series

Message ID 20191002124749.7503-2-jjhiblot@ti.com
State Changes Requested
Delegated to: Tom Rini
Headers show
Series
  • drivers: Add a framework for MUX drivers
Related show

Commit Message

Jean-Jacques Hiblot Oct. 2, 2019, 12:47 p.m. UTC
Add a new subsystem that handles multiplexer controllers. The API is the
same as in Linux.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
---

 drivers/Kconfig               |   2 +
 drivers/Makefile              |   1 +
 drivers/mux/Kconfig           |   7 +
 drivers/mux/Makefile          |   6 +
 drivers/mux/mux-uclass.c      | 296 ++++++++++++++++++++++++++++++++++
 include/dm/uclass-id.h        |   1 +
 include/dt-bindings/mux/mux.h |  17 ++
 include/mux-internal.h        |  80 +++++++++
 include/mux.h                 | 114 +++++++++++++
 9 files changed, 524 insertions(+)
 create mode 100644 drivers/mux/Kconfig
 create mode 100644 drivers/mux/Makefile
 create mode 100644 drivers/mux/mux-uclass.c
 create mode 100644 include/dt-bindings/mux/mux.h
 create mode 100644 include/mux-internal.h
 create mode 100644 include/mux.h

Comments

Simon Glass Oct. 30, 2019, 1:48 a.m. UTC | #1
Hi Jean-Jacques,

On Wed, 2 Oct 2019 at 06:47, Jean-Jacques Hiblot <jjhiblot@ti.com> wrote:
>
> Add a new subsystem that handles multiplexer controllers. The API is the
> same as in Linux.
>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
> ---
>
>  drivers/Kconfig               |   2 +
>  drivers/Makefile              |   1 +
>  drivers/mux/Kconfig           |   7 +
>  drivers/mux/Makefile          |   6 +
>  drivers/mux/mux-uclass.c      | 296 ++++++++++++++++++++++++++++++++++
>  include/dm/uclass-id.h        |   1 +
>  include/dt-bindings/mux/mux.h |  17 ++
>  include/mux-internal.h        |  80 +++++++++
>  include/mux.h                 | 114 +++++++++++++
>  9 files changed, 524 insertions(+)
>  create mode 100644 drivers/mux/Kconfig
>  create mode 100644 drivers/mux/Makefile
>  create mode 100644 drivers/mux/mux-uclass.c
>  create mode 100644 include/dt-bindings/mux/mux.h
>  create mode 100644 include/mux-internal.h
>  create mode 100644 include/mux.h
>

I feel this needs more documentation. What is a multiplexer?

> diff --git a/drivers/Kconfig b/drivers/Kconfig
> index 350acf81f3..5334974ad4 100644
> --- a/drivers/Kconfig
> +++ b/drivers/Kconfig
> @@ -60,6 +60,8 @@ source "drivers/mmc/Kconfig"
>
>  source "drivers/mtd/Kconfig"
>
> +source "drivers/mux/Kconfig"
> +
>  source "drivers/net/Kconfig"
>
>  source "drivers/nvme/Kconfig"
> diff --git a/drivers/Makefile b/drivers/Makefile
> index a4bb5e4975..f4d71f3b3c 100644
> --- a/drivers/Makefile
> +++ b/drivers/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_$(SPL_TPL_)INPUT) += input/
>  obj-$(CONFIG_$(SPL_TPL_)LED) += led/
>  obj-$(CONFIG_$(SPL_TPL_)MMC_SUPPORT) += mmc/
>  obj-$(CONFIG_$(SPL_TPL_)NAND_SUPPORT) += mtd/nand/raw/
> +obj-$(CONFIG_$(SPl_)MULTIPLEXER) += mux/

SPL?

>  obj-$(CONFIG_$(SPL_TPL_)PCH_SUPPORT) += pch/
>  obj-$(CONFIG_$(SPL_TPL_)PCI) += pci/
>  obj-$(CONFIG_$(SPL_TPL_)PHY) += phy/
> diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
> new file mode 100644
> index 0000000000..ad0199c058
> --- /dev/null
> +++ b/drivers/mux/Kconfig
> @@ -0,0 +1,7 @@
> +menu "Multiplexer drivers"
> +
> +config MULTIPLEXER
> +       bool "Multiplexer Support"
> +       depends on DM
> +
> +endmenu
> diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
> new file mode 100644
> index 0000000000..351e4363d3
> --- /dev/null
> +++ b/drivers/mux/Makefile
> @@ -0,0 +1,6 @@
> +# SPDX-License-Identifier: GPL-2.0+
> +#
> +# (C) Copyright 2019
> +# Jean-Jacques Hiblot <jjhiblot@ti.com>
> +
> +obj-$(CONFIG_$(SPL_)MULTIPLEXER) += mux-uclass.o
> diff --git a/drivers/mux/mux-uclass.c b/drivers/mux/mux-uclass.c
> new file mode 100644
> index 0000000000..58998af29c
> --- /dev/null
> +++ b/drivers/mux/mux-uclass.c
> @@ -0,0 +1,296 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Multiplexer subsystem
> + *
> + * Based on the linux multiplexer framework
> + *
> + * Copyright (C) 2017 Axentia Technologies AB
> + * Author: Peter Rosin <peda@axentia.se>
> + *
> + * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
> + * Jean-Jacques Hiblot <jjhiblot@ti.com>
> + */
> +
> +#include <common.h>
> +#include <mux-internal.h>

should go above the dm/device-internal

> +#include <dm.h>
> +#include <dt-structs.h>

Shouldn't need this
> +#include <errno.h>

Shouldn't need this

> +#include <dm/device-internal.h>
> +#include <dm/lists.h>
> +#include <dm/read.h>

Shouldn't need this

> +#include <dt-bindings/mux/mux.h>
> +
> +/*
> + * The idle-as-is "state" is not an actual state that may be selected, it
> + * only implies that the state should not be changed. So, use that state
> + * as indication that the cached state of the multiplexer is unknown.
> + */
> +#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS
> +
> +static inline const struct mux_control_ops *mux_dev_ops(struct udevice *dev)
> +{
> +       return (const struct mux_control_ops *)dev->driver->ops;
> +}
> +
> +static int mux_control_set(struct mux_control *mux, int state)
> +{
> +       int ret = mux_dev_ops(mux->dev)->set(mux, state);
> +
> +       mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;
> +
> +       return ret;
> +}
> +
> +unsigned int mux_control_states(struct mux_control *mux)
> +{
> +       return mux->states;
> +}
> +
> +static int __mux_control_select(struct mux_control *mux, int state)
> +{
> +       int ret;
> +
> +       if (WARN_ON(state < 0 || state >= mux->states))
> +               return -EINVAL;
> +
> +       if (mux->cached_state == state)
> +               return 0;
> +
> +       ret = mux_control_set(mux, state);
> +       if (ret >= 0)
> +               return 0;
> +
> +       /* The mux update failed, try to revert if appropriate... */
> +       if (mux->idle_state != MUX_IDLE_AS_IS)
> +               mux_control_set(mux, mux->idle_state);
> +
> +       return ret;
> +}
> +
> +int mux_control_select(struct mux_control *mux, unsigned int state)
> +{
> +       int ret;
> +
> +       if (mux->in_use)
> +               return -EBUSY;
> +
> +       ret = __mux_control_select(mux, state);
> +
> +       if (ret < 0)
> +               return ret;
> +
> +       mux->in_use = true;
> +
> +       return 0;
> +}
> +
> +int mux_control_deselect(struct mux_control *mux)
> +{
> +       int ret = 0;
> +
> +       if (mux->idle_state != MUX_IDLE_AS_IS &&
> +           mux->idle_state != mux->cached_state)
> +               ret = mux_control_set(mux, mux->idle_state);
> +
> +       mux->in_use = false;
> +
> +       return ret;
> +}
> +
> +static int mux_of_xlate_default(struct mux_chip *mux_chip,
> +                               struct ofnode_phandle_args *args,
> +                               struct mux_control **muxp)
> +{
> +       struct mux_control *mux;
> +       int id;
> +
> +       debug("%s(mux=%p)\n", __func__, mux);
> +
> +       if (args->args_count > 1) {
> +               debug("Invaild args_count: %d\n", args->args_count);
> +               return -EINVAL;
> +       }
> +
> +       if (args->args_count)
> +               id = args->args[0];
> +       else
> +               id = 0;
> +
> +       if (id >= mux_chip->controllers) {
> +               dev_err(dev, "bad mux controller %u specified in %s\n",
> +                       id, ofnode_get_name(args->node));
> +               return -ERANGE;
> +       }
> +
> +       mux = &mux_chip->mux[id];
> +       mux->id = id;
> +       *muxp = mux;
> +       return 0;
> +}
> +
> +static int mux_get_by_indexed_prop(struct udevice *dev, const char *prop_name,
> +                                  int index, struct mux_control **mux)
> +{
> +       int ret;
> +       struct ofnode_phandle_args args;
> +       struct udevice *dev_mux;
> +       const struct mux_control_ops *ops;
> +       struct mux_chip *mux_chip;
> +
> +       debug("%s(dev=%p, index=%d, mux=%p)\n", __func__, dev, index, mux);
> +
> +       ret = dev_read_phandle_with_args(dev, prop_name, "#mux-control-cells",
> +                                        0, index, &args);
> +       if (ret) {
> +               debug("%s: fdtdec_parse_phandle_with_args failed: err=%d\n",
> +                     __func__, ret);
> +               return ret;
> +       }
> +
> +       ret = uclass_get_device_by_ofnode(UCLASS_MUX, args.node, &dev_mux);
> +       if (ret) {
> +               debug("%s: uclass_get_device_by_ofnode failed: err=%d\n",
> +                     __func__, ret);
> +               return ret;
> +       }
> +
> +       mux_chip = dev_get_uclass_priv(dev_mux);
> +
> +       ops = mux_dev_ops(dev_mux);
> +       if (ops->of_xlate)
> +               ret = ops->of_xlate(mux_chip, &args, mux);
> +       else
> +               ret = mux_of_xlate_default(mux_chip, &args, mux);
> +       if (ret) {
> +               debug("of_xlate() failed: %d\n", ret);
> +               return ret;
> +       }
> +       (*mux)->dev = dev_mux;
> +
> +       return 0;
> +}
> +
> +int mux_get_by_index(struct udevice *dev, int index, struct mux_control **mux)
> +{
> +       return mux_get_by_indexed_prop(dev, "mux-controls", index, mux);
> +}
> +
> +int mux_control_get(struct udevice *dev, const char *name,
> +                   struct mux_control **mux)
> +{
> +       int index;
> +
> +       debug("%s(dev=%p, name=%s, mux=%p)\n", __func__, dev, name, mux);
> +
> +       index = dev_read_stringlist_search(dev, "mux-control-names", name);
> +       if (index < 0) {
> +               debug("fdt_stringlist_search() failed: %d\n", index);
> +               return index;
> +       }
> +
> +       return mux_get_by_index(dev, index, mux);
> +}
> +
> +void mux_control_put(struct mux_control *mux)
> +{
> +       mux_control_deselect(mux);
> +}
> +
> +static void devm_mux_control_release(struct udevice *dev, void *res)
> +{
> +       mux_control_put(*(struct mux_control **)res);
> +}
> +
> +struct mux_control *devm_mux_control_get(struct udevice *dev, const char *id)
> +{
> +       int rc;
> +       struct mux_control **mux;
> +
> +       mux = devres_alloc(devm_mux_control_release,
> +                          sizeof(struct mux_control *), __GFP_ZERO);
> +       if (unlikely(!mux))
> +               return ERR_PTR(-ENOMEM);
> +
> +       rc = mux_control_get(dev, id, mux);
> +       if (rc)
> +               return ERR_PTR(rc);
> +
> +       devres_add(dev, mux);
> +       return *mux;
> +}
> +
> +int mux_alloc_controllers(struct udevice *dev, unsigned int controllers)
> +{
> +       int i;
> +       struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
> +
> +       mux_chip->mux = devm_kmalloc(dev,
> +                                    sizeof(struct mux_control) * controllers,
> +                                    __GFP_ZERO);
> +       if (!mux_chip->mux)
> +               return -ENOMEM;
> +
> +       mux_chip->controllers = controllers;
> +
> +       for (i = 0; i < mux_chip->controllers; ++i) {
> +               struct mux_control *mux = &mux_chip->mux[i];
> +
> +               mux->dev = dev;
> +               mux->cached_state = MUX_CACHE_UNKNOWN;
> +               mux->idle_state = MUX_IDLE_AS_IS;
> +               mux->in_use = false;
> +               mux->id = i;
> +       }
> +
> +       return 0;
> +}
> +
> +int mux_uclass_post_probe(struct udevice *dev)
> +{
> +       int i, ret;
> +       struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
> +
> +       for (i = 0; i < mux_chip->controllers; ++i) {
> +               struct mux_control *mux = &mux_chip->mux[i];
> +
> +               if (mux->idle_state == mux->cached_state)
> +                       continue;
> +
> +               ret = mux_control_set(mux, mux->idle_state);
> +               if (ret < 0) {
> +                       dev_err(&mux_chip->dev, "unable to set idle state\n");
> +                       return ret;
> +               }
> +       }
> +       return 0;
> +}
> +
> +void dm_mux_init(void)
> +{
> +       struct uclass *uc;
> +       struct udevice *dev;
> +       int ret;
> +
> +       ret = uclass_get(UCLASS_MUX, &uc);
> +       if (ret < 0) {
> +               debug("unable to get MUX uclass\n");
> +               return;
> +       }
> +       uclass_foreach_dev(dev, uc) {
> +               if (dev_read_bool(dev, "u-boot,mux-autoprobe")) {
> +                       ret = device_probe(dev);
> +                       if (ret)
> +                               debug("unable to probe device %s\n", dev->name);
> +               } else {
> +                       printf("not found for dev %s\n", dev->name);
> +               }
> +       }
> +}
> +
> +UCLASS_DRIVER(mux) = {
> +       .id             = UCLASS_MUX,
> +       .name           = "mux",
> +       .post_probe     = mux_uclass_post_probe,
> +       .per_device_auto_alloc_size = sizeof(struct mux_chip),
> +};
> diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
> index d4d96106b3..869c0616bd 100644
> --- a/include/dm/uclass-id.h
> +++ b/include/dm/uclass-id.h
> @@ -64,6 +64,7 @@ enum uclass_id {
>         UCLASS_MMC,             /* SD / MMC card or chip */
>         UCLASS_MOD_EXP,         /* RSA Mod Exp device */
>         UCLASS_MTD,             /* Memory Technology Device (MTD) device */
> +       UCLASS_MUX,             /* Multiplexer device */
>         UCLASS_NOP,             /* No-op devices */
>         UCLASS_NORTHBRIDGE,     /* Intel Northbridge / SDRAM controller */
>         UCLASS_NVME,            /* NVM Express device */
> diff --git a/include/dt-bindings/mux/mux.h b/include/dt-bindings/mux/mux.h
> new file mode 100644
> index 0000000000..042719218d
> --- /dev/null
> +++ b/include/dt-bindings/mux/mux.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * This header provides constants for most Multiplexer bindings.
> + *
> + * Most Multiplexer bindings specify an idle state. In most cases, the
> + * the multiplexer can be left as is when idle, and in some cases it can
> + * disconnect the input/output and leave the multiplexer in a high
> + * impedance state.

<add more details...what is a mux?>

How do I use this API?

> + */
> +
> +#ifndef _DT_BINDINGS_MUX_MUX_H
> +#define _DT_BINDINGS_MUX_MUX_H
> +
> +#define MUX_IDLE_AS_IS      (-1)
> +#define MUX_IDLE_DISCONNECT (-2)
> +
> +#endif
> diff --git a/include/mux-internal.h b/include/mux-internal.h
> new file mode 100644
> index 0000000000..63444f4c3d
> --- /dev/null
> +++ b/include/mux-internal.h
> @@ -0,0 +1,80 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Based on the linux multiplexer framework
> + *
> + * Copyright (C) 2017 Axentia Technologies AB
> + * Author: Peter Rosin <peda@axentia.se>
> + *
> + * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
> + * Jean-Jacques Hiblot <jjhiblot@ti.com>
> + */
> +
> +#ifndef _MUX_UCLASS_H
> +#define _MUX_UCLASS_H
> +
> +/* See mux.h for background documentation. */
> +
> +#include <mux.h>
> +
> +struct ofnode_phandle_args;
> +
> +/**
> + * struct mux_chip -   Represents a chip holding mux controllers.
> + * @controllers:       Number of mux controllers handled by the chip.
> + * @mux:               Array of mux controllers that are handled.
> + * @dev:               Device structure.
> + * @ops:               Mux controller operations.

Mention that this is per-device uclass-private data.

> + */
> +struct mux_chip {
> +       unsigned int controllers;
> +       struct mux_control *mux;
> +};
> +
> +/**
> + * struct mux_control_ops -    Mux controller operations for a mux chip.
> + * @set:                       Set the state of the given mux controller.
> + */
> +struct mux_control_ops {
> +       int (*set)(struct mux_control *mux, int state);
> +       int (*of_xlate)(struct mux_chip *dev_mux,
> +                       struct ofnode_phandle_args *args,
> +                       struct mux_control **mux);

Function comments

> +};
> +
> +/**
> + * struct mux_control -        Represents a mux controller.
> + * @chip:              The mux chip that is handling this mux controller.
> + * @cached_state:      The current mux controller state, or -1 if none.
> + * @states:            The number of mux controller states.
> + * @idle_state:                The mux controller state to use when inactive, or one
> + *                     of MUX_IDLE_AS_IS and MUX_IDLE_DISCONNECT.
> + *
> + * Mux drivers may only change @states and @idle_state, and may only do so
> + * between allocation and registration of the mux controller. Specifically,
> + * @cached_state is internal to the mux core and should never be written by
> + * mux drivers.

How do I get from a struct udevice * to this struct? Is it private data?

> + */
> +struct mux_control {
> +       bool    in_use;
> +       struct udevice *dev;
> +       int cached_state;
> +       unsigned int states;
> +       int idle_state;
> +       int id;
> +};
> +
> +/**
> + * mux_control_get_index() - Get the index of the given mux controller
> + * @mux: The mux-control to get the index for.
> + *
> + * Return: The index of the mux controller within the mux chip the mux
> + * controller is a part of.
> + */
> +static inline unsigned int mux_control_get_index(struct mux_control *mux)
> +{
> +       return mux->id;
> +}
> +
> +int mux_alloc_controllers(struct udevice *dev, unsigned int controllers);
> +
> +#endif

[..]

Regards,
Simon
Jean-Jacques Hiblot Nov. 4, 2019, 5:53 p.m. UTC | #2
Hi Simon,

Thank for the review.

On 30/10/2019 02:48, Simon Glass wrote:
> Hi Jean-Jacques,
>
> On Wed, 2 Oct 2019 at 06:47, Jean-Jacques Hiblot <jjhiblot@ti.com> wrote:
>> Add a new subsystem that handles multiplexer controllers. The API is the
>> same as in Linux.
>>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
>> ---
>>
>>   drivers/Kconfig               |   2 +
>>   drivers/Makefile              |   1 +
>>   drivers/mux/Kconfig           |   7 +
>>   drivers/mux/Makefile          |   6 +
>>   drivers/mux/mux-uclass.c      | 296 ++++++++++++++++++++++++++++++++++
>>   include/dm/uclass-id.h        |   1 +
>>   include/dt-bindings/mux/mux.h |  17 ++
>>   include/mux-internal.h        |  80 +++++++++
>>   include/mux.h                 | 114 +++++++++++++
>>   9 files changed, 524 insertions(+)
>>   create mode 100644 drivers/mux/Kconfig
>>   create mode 100644 drivers/mux/Makefile
>>   create mode 100644 drivers/mux/mux-uclass.c
>>   create mode 100644 include/dt-bindings/mux/mux.h
>>   create mode 100644 include/mux-internal.h
>>   create mode 100644 include/mux.h
>>
> I feel this needs more documentation. What is a multiplexer?

I'll add a description of what a mux is in include/mux.h

>
>> diff --git a/drivers/Kconfig b/drivers/Kconfig
>> index 350acf81f3..5334974ad4 100644
>> --- a/drivers/Kconfig
>> +++ b/drivers/Kconfig
>> @@ -60,6 +60,8 @@ source "drivers/mmc/Kconfig"
>>
>>   source "drivers/mtd/Kconfig"
>>
>> +source "drivers/mux/Kconfig"
>> +
>>   source "drivers/net/Kconfig"
>>
>>   source "drivers/nvme/Kconfig"
>> diff --git a/drivers/Makefile b/drivers/Makefile
>> index a4bb5e4975..f4d71f3b3c 100644
>> --- a/drivers/Makefile
>> +++ b/drivers/Makefile
>> @@ -12,6 +12,7 @@ obj-$(CONFIG_$(SPL_TPL_)INPUT) += input/
>>   obj-$(CONFIG_$(SPL_TPL_)LED) += led/
>>   obj-$(CONFIG_$(SPL_TPL_)MMC_SUPPORT) += mmc/
>>   obj-$(CONFIG_$(SPL_TPL_)NAND_SUPPORT) += mtd/nand/raw/
>> +obj-$(CONFIG_$(SPl_)MULTIPLEXER) += mux/
> SPL?
good catch
>
>>   obj-$(CONFIG_$(SPL_TPL_)PCH_SUPPORT) += pch/
>>   obj-$(CONFIG_$(SPL_TPL_)PCI) += pci/
>>   obj-$(CONFIG_$(SPL_TPL_)PHY) += phy/
>> diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
>> new file mode 100644
>> index 0000000000..ad0199c058
>> --- /dev/null
>> +++ b/drivers/mux/Kconfig
>> @@ -0,0 +1,7 @@
>> +menu "Multiplexer drivers"
>> +
>> +config MULTIPLEXER
>> +       bool "Multiplexer Support"
>> +       depends on DM
>> +
>> +endmenu
>> diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
>> new file mode 100644
>> index 0000000000..351e4363d3
>> --- /dev/null
>> +++ b/drivers/mux/Makefile
>> @@ -0,0 +1,6 @@
>> +# SPDX-License-Identifier: GPL-2.0+
>> +#
>> +# (C) Copyright 2019
>> +# Jean-Jacques Hiblot <jjhiblot@ti.com>
>> +
>> +obj-$(CONFIG_$(SPL_)MULTIPLEXER) += mux-uclass.o
>> diff --git a/drivers/mux/mux-uclass.c b/drivers/mux/mux-uclass.c
>> new file mode 100644
>> index 0000000000..58998af29c
>> --- /dev/null
>> +++ b/drivers/mux/mux-uclass.c
>> @@ -0,0 +1,296 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Multiplexer subsystem
>> + *
>> + * Based on the linux multiplexer framework
>> + *
>> + * Copyright (C) 2017 Axentia Technologies AB
>> + * Author: Peter Rosin <peda@axentia.se>
>> + *
>> + * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
>> + * Jean-Jacques Hiblot <jjhiblot@ti.com>
>> + */
>> +
>> +#include <common.h>
>> +#include <mux-internal.h>
> should go above the dm/device-internal
>
>> +#include <dm.h>
>> +#include <dt-structs.h>
> Shouldn't need this
>> +#include <errno.h>
> Shouldn't need this
>
>> +#include <dm/device-internal.h>
>> +#include <dm/lists.h>
>> +#include <dm/read.h>
> Shouldn't need this
I'll cleanup the headers in v2.
>
>> +#include <dt-bindings/mux/mux.h>
>> +
>> +/*
>> + * The idle-as-is "state" is not an actual state that may be selected, it
>> + * only implies that the state should not be changed. So, use that state
>> + * as indication that the cached state of the multiplexer is unknown.
>> + */
>> +#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS
>> +
>> +static inline const struct mux_control_ops *mux_dev_ops(struct udevice *dev)
>> +{
>> +       return (const struct mux_control_ops *)dev->driver->ops;
>> +}
>> +
>> +static int mux_control_set(struct mux_control *mux, int state)
>> +{
>> +       int ret = mux_dev_ops(mux->dev)->set(mux, state);
>> +
>> +       mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;
>> +
>> +       return ret;
>> +}
>> +
>> +unsigned int mux_control_states(struct mux_control *mux)
>> +{
>> +       return mux->states;
>> +}
>> +
>> +static int __mux_control_select(struct mux_control *mux, int state)
>> +{
>> +       int ret;
>> +
>> +       if (WARN_ON(state < 0 || state >= mux->states))
>> +               return -EINVAL;
>> +
>> +       if (mux->cached_state == state)
>> +               return 0;
>> +
>> +       ret = mux_control_set(mux, state);
>> +       if (ret >= 0)
>> +               return 0;
>> +
>> +       /* The mux update failed, try to revert if appropriate... */
>> +       if (mux->idle_state != MUX_IDLE_AS_IS)
>> +               mux_control_set(mux, mux->idle_state);
>> +
>> +       return ret;
>> +}
>> +
>> +int mux_control_select(struct mux_control *mux, unsigned int state)
>> +{
>> +       int ret;
>> +
>> +       if (mux->in_use)
>> +               return -EBUSY;
>> +
>> +       ret = __mux_control_select(mux, state);
>> +
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       mux->in_use = true;
>> +
>> +       return 0;
>> +}
>> +
>> +int mux_control_deselect(struct mux_control *mux)
>> +{
>> +       int ret = 0;
>> +
>> +       if (mux->idle_state != MUX_IDLE_AS_IS &&
>> +           mux->idle_state != mux->cached_state)
>> +               ret = mux_control_set(mux, mux->idle_state);
>> +
>> +       mux->in_use = false;
>> +
>> +       return ret;
>> +}
>> +
>> +static int mux_of_xlate_default(struct mux_chip *mux_chip,
>> +                               struct ofnode_phandle_args *args,
>> +                               struct mux_control **muxp)
>> +{
>> +       struct mux_control *mux;
>> +       int id;
>> +
>> +       debug("%s(mux=%p)\n", __func__, mux);
>> +
>> +       if (args->args_count > 1) {
>> +               debug("Invaild args_count: %d\n", args->args_count);
>> +               return -EINVAL;
>> +       }
>> +
>> +       if (args->args_count)
>> +               id = args->args[0];
>> +       else
>> +               id = 0;
>> +
>> +       if (id >= mux_chip->controllers) {
>> +               dev_err(dev, "bad mux controller %u specified in %s\n",
>> +                       id, ofnode_get_name(args->node));
>> +               return -ERANGE;
>> +       }
>> +
>> +       mux = &mux_chip->mux[id];
>> +       mux->id = id;
>> +       *muxp = mux;
>> +       return 0;
>> +}
>> +
>> +static int mux_get_by_indexed_prop(struct udevice *dev, const char *prop_name,
>> +                                  int index, struct mux_control **mux)
>> +{
>> +       int ret;
>> +       struct ofnode_phandle_args args;
>> +       struct udevice *dev_mux;
>> +       const struct mux_control_ops *ops;
>> +       struct mux_chip *mux_chip;
>> +
>> +       debug("%s(dev=%p, index=%d, mux=%p)\n", __func__, dev, index, mux);
>> +
>> +       ret = dev_read_phandle_with_args(dev, prop_name, "#mux-control-cells",
>> +                                        0, index, &args);
>> +       if (ret) {
>> +               debug("%s: fdtdec_parse_phandle_with_args failed: err=%d\n",
>> +                     __func__, ret);
>> +               return ret;
>> +       }
>> +
>> +       ret = uclass_get_device_by_ofnode(UCLASS_MUX, args.node, &dev_mux);
>> +       if (ret) {
>> +               debug("%s: uclass_get_device_by_ofnode failed: err=%d\n",
>> +                     __func__, ret);
>> +               return ret;
>> +       }
>> +
>> +       mux_chip = dev_get_uclass_priv(dev_mux);
>> +
>> +       ops = mux_dev_ops(dev_mux);
>> +       if (ops->of_xlate)
>> +               ret = ops->of_xlate(mux_chip, &args, mux);
>> +       else
>> +               ret = mux_of_xlate_default(mux_chip, &args, mux);
>> +       if (ret) {
>> +               debug("of_xlate() failed: %d\n", ret);
>> +               return ret;
>> +       }
>> +       (*mux)->dev = dev_mux;
>> +
>> +       return 0;
>> +}
>> +
>> +int mux_get_by_index(struct udevice *dev, int index, struct mux_control **mux)
>> +{
>> +       return mux_get_by_indexed_prop(dev, "mux-controls", index, mux);
>> +}
>> +
>> +int mux_control_get(struct udevice *dev, const char *name,
>> +                   struct mux_control **mux)
>> +{
>> +       int index;
>> +
>> +       debug("%s(dev=%p, name=%s, mux=%p)\n", __func__, dev, name, mux);
>> +
>> +       index = dev_read_stringlist_search(dev, "mux-control-names", name);
>> +       if (index < 0) {
>> +               debug("fdt_stringlist_search() failed: %d\n", index);
>> +               return index;
>> +       }
>> +
>> +       return mux_get_by_index(dev, index, mux);
>> +}
>> +
>> +void mux_control_put(struct mux_control *mux)
>> +{
>> +       mux_control_deselect(mux);
>> +}
>> +
>> +static void devm_mux_control_release(struct udevice *dev, void *res)
>> +{
>> +       mux_control_put(*(struct mux_control **)res);
>> +}
>> +
>> +struct mux_control *devm_mux_control_get(struct udevice *dev, const char *id)
>> +{
>> +       int rc;
>> +       struct mux_control **mux;
>> +
>> +       mux = devres_alloc(devm_mux_control_release,
>> +                          sizeof(struct mux_control *), __GFP_ZERO);
>> +       if (unlikely(!mux))
>> +               return ERR_PTR(-ENOMEM);
>> +
>> +       rc = mux_control_get(dev, id, mux);
>> +       if (rc)
>> +               return ERR_PTR(rc);
>> +
>> +       devres_add(dev, mux);
>> +       return *mux;
>> +}
>> +
>> +int mux_alloc_controllers(struct udevice *dev, unsigned int controllers)
>> +{
>> +       int i;
>> +       struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
>> +
>> +       mux_chip->mux = devm_kmalloc(dev,
>> +                                    sizeof(struct mux_control) * controllers,
>> +                                    __GFP_ZERO);
>> +       if (!mux_chip->mux)
>> +               return -ENOMEM;
>> +
>> +       mux_chip->controllers = controllers;
>> +
>> +       for (i = 0; i < mux_chip->controllers; ++i) {
>> +               struct mux_control *mux = &mux_chip->mux[i];
>> +
>> +               mux->dev = dev;
>> +               mux->cached_state = MUX_CACHE_UNKNOWN;
>> +               mux->idle_state = MUX_IDLE_AS_IS;
>> +               mux->in_use = false;
>> +               mux->id = i;
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>> +int mux_uclass_post_probe(struct udevice *dev)
>> +{
>> +       int i, ret;
>> +       struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
>> +
>> +       for (i = 0; i < mux_chip->controllers; ++i) {
>> +               struct mux_control *mux = &mux_chip->mux[i];
>> +
>> +               if (mux->idle_state == mux->cached_state)
>> +                       continue;
>> +
>> +               ret = mux_control_set(mux, mux->idle_state);
>> +               if (ret < 0) {
>> +                       dev_err(&mux_chip->dev, "unable to set idle state\n");
>> +                       return ret;
>> +               }
>> +       }
>> +       return 0;
>> +}
>> +
>> +void dm_mux_init(void)
>> +{
>> +       struct uclass *uc;
>> +       struct udevice *dev;
>> +       int ret;
>> +
>> +       ret = uclass_get(UCLASS_MUX, &uc);
>> +       if (ret < 0) {
>> +               debug("unable to get MUX uclass\n");
>> +               return;
>> +       }
>> +       uclass_foreach_dev(dev, uc) {
>> +               if (dev_read_bool(dev, "u-boot,mux-autoprobe")) {
>> +                       ret = device_probe(dev);
>> +                       if (ret)
>> +                               debug("unable to probe device %s\n", dev->name);
>> +               } else {
>> +                       printf("not found for dev %s\n", dev->name);
>> +               }
>> +       }
>> +}
>> +
>> +UCLASS_DRIVER(mux) = {
>> +       .id             = UCLASS_MUX,
>> +       .name           = "mux",
>> +       .post_probe     = mux_uclass_post_probe,
>> +       .per_device_auto_alloc_size = sizeof(struct mux_chip),
>> +};
>> diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
>> index d4d96106b3..869c0616bd 100644
>> --- a/include/dm/uclass-id.h
>> +++ b/include/dm/uclass-id.h
>> @@ -64,6 +64,7 @@ enum uclass_id {
>>          UCLASS_MMC,             /* SD / MMC card or chip */
>>          UCLASS_MOD_EXP,         /* RSA Mod Exp device */
>>          UCLASS_MTD,             /* Memory Technology Device (MTD) device */
>> +       UCLASS_MUX,             /* Multiplexer device */
>>          UCLASS_NOP,             /* No-op devices */
>>          UCLASS_NORTHBRIDGE,     /* Intel Northbridge / SDRAM controller */
>>          UCLASS_NVME,            /* NVM Express device */
>> diff --git a/include/dt-bindings/mux/mux.h b/include/dt-bindings/mux/mux.h
>> new file mode 100644
>> index 0000000000..042719218d
>> --- /dev/null
>> +++ b/include/dt-bindings/mux/mux.h
>> @@ -0,0 +1,17 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * This header provides constants for most Multiplexer bindings.
>> + *
>> + * Most Multiplexer bindings specify an idle state. In most cases, the
>> + * the multiplexer can be left as is when idle, and in some cases it can
>> + * disconnect the input/output and leave the multiplexer in a high
>> + * impedance state.
> <add more details...what is a mux?>
>
> How do I use this API?
The API is described by the comments in include/mux.h
>
>> + */
>> +
>> +#ifndef _DT_BINDINGS_MUX_MUX_H
>> +#define _DT_BINDINGS_MUX_MUX_H
>> +
>> +#define MUX_IDLE_AS_IS      (-1)
>> +#define MUX_IDLE_DISCONNECT (-2)
>> +
>> +#endif
>> diff --git a/include/mux-internal.h b/include/mux-internal.h
>> new file mode 100644
>> index 0000000000..63444f4c3d
>> --- /dev/null
>> +++ b/include/mux-internal.h
>> @@ -0,0 +1,80 @@
>> +/* SPDX-License-Identifier: GPL-2.0+ */
>> +/*
>> + * Based on the linux multiplexer framework
>> + *
>> + * Copyright (C) 2017 Axentia Technologies AB
>> + * Author: Peter Rosin <peda@axentia.se>
>> + *
>> + * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
>> + * Jean-Jacques Hiblot <jjhiblot@ti.com>
>> + */
>> +
>> +#ifndef _MUX_UCLASS_H
>> +#define _MUX_UCLASS_H
>> +
>> +/* See mux.h for background documentation. */
>> +
>> +#include <mux.h>
>> +
>> +struct ofnode_phandle_args;
>> +
>> +/**
>> + * struct mux_chip -   Represents a chip holding mux controllers.
>> + * @controllers:       Number of mux controllers handled by the chip.
>> + * @mux:               Array of mux controllers that are handled.
>> + * @dev:               Device structure.
>> + * @ops:               Mux controller operations.
> Mention that this is per-device uclass-private data.
>
>> + */
>> +struct mux_chip {
>> +       unsigned int controllers;
>> +       struct mux_control *mux;
>> +};
>> +
>> +/**
>> + * struct mux_control_ops -    Mux controller operations for a mux chip.
>> + * @set:                       Set the state of the given mux controller.
>> + */
>> +struct mux_control_ops {
>> +       int (*set)(struct mux_control *mux, int state);
>> +       int (*of_xlate)(struct mux_chip *dev_mux,
>> +                       struct ofnode_phandle_args *args,
>> +                       struct mux_control **mux);
> Function comments
>
>> +};
>> +
>> +/**
>> + * struct mux_control -        Represents a mux controller.
>> + * @chip:              The mux chip that is handling this mux controller.
>> + * @cached_state:      The current mux controller state, or -1 if none.
>> + * @states:            The number of mux controller states.
>> + * @idle_state:                The mux controller state to use when inactive, or one
>> + *                     of MUX_IDLE_AS_IS and MUX_IDLE_DISCONNECT.
>> + *
>> + * Mux drivers may only change @states and @idle_state, and may only do so
>> + * between allocation and registration of the mux controller. Specifically,
>> + * @cached_state is internal to the mux core and should never be written by
>> + * mux drivers.
> How do I get from a struct udevice * to this struct? Is it private data?

This is not private data per-se. It is intended to be used by a client 
device.

You get a mux_control* with mux_control_get() and devm_mux_control_get().


JJ

>
>> + */
>> +struct mux_control {
>> +       bool    in_use;
>> +       struct udevice *dev;
>> +       int cached_state;
>> +       unsigned int states;
>> +       int idle_state;
>> +       int id;
>> +};
>> +
>> +/**
>> + * mux_control_get_index() - Get the index of the given mux controller
>> + * @mux: The mux-control to get the index for.
>> + *
>> + * Return: The index of the mux controller within the mux chip the mux
>> + * controller is a part of.
>> + */
>> +static inline unsigned int mux_control_get_index(struct mux_control *mux)
>> +{
>> +       return mux->id;
>> +}
>> +
>> +int mux_alloc_controllers(struct udevice *dev, unsigned int controllers);
>> +
>> +#endif
> [..]
>
> Regards,
> Simon
>
Bin Meng Nov. 5, 2019, 1:37 a.m. UTC | #3
+Alex who once worked in MUX on LS1028 IIRC.

On Wed, Oct 2, 2019 at 8:47 PM Jean-Jacques Hiblot <jjhiblot@ti.com> wrote:
>
> Add a new subsystem that handles multiplexer controllers. The API is the
> same as in Linux.
>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
> ---
>
>  drivers/Kconfig               |   2 +
>  drivers/Makefile              |   1 +
>  drivers/mux/Kconfig           |   7 +
>  drivers/mux/Makefile          |   6 +
>  drivers/mux/mux-uclass.c      | 296 ++++++++++++++++++++++++++++++++++
>  include/dm/uclass-id.h        |   1 +
>  include/dt-bindings/mux/mux.h |  17 ++
>  include/mux-internal.h        |  80 +++++++++
>  include/mux.h                 | 114 +++++++++++++
>  9 files changed, 524 insertions(+)
>  create mode 100644 drivers/mux/Kconfig
>  create mode 100644 drivers/mux/Makefile
>  create mode 100644 drivers/mux/mux-uclass.c
>  create mode 100644 include/dt-bindings/mux/mux.h
>  create mode 100644 include/mux-internal.h
>  create mode 100644 include/mux.h
>

Regards,
Bin

Patch
diff mbox series

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 350acf81f3..5334974ad4 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -60,6 +60,8 @@  source "drivers/mmc/Kconfig"
 
 source "drivers/mtd/Kconfig"
 
+source "drivers/mux/Kconfig"
+
 source "drivers/net/Kconfig"
 
 source "drivers/nvme/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index a4bb5e4975..f4d71f3b3c 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -12,6 +12,7 @@  obj-$(CONFIG_$(SPL_TPL_)INPUT) += input/
 obj-$(CONFIG_$(SPL_TPL_)LED) += led/
 obj-$(CONFIG_$(SPL_TPL_)MMC_SUPPORT) += mmc/
 obj-$(CONFIG_$(SPL_TPL_)NAND_SUPPORT) += mtd/nand/raw/
+obj-$(CONFIG_$(SPl_)MULTIPLEXER) += mux/
 obj-$(CONFIG_$(SPL_TPL_)PCH_SUPPORT) += pch/
 obj-$(CONFIG_$(SPL_TPL_)PCI) += pci/
 obj-$(CONFIG_$(SPL_TPL_)PHY) += phy/
diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
new file mode 100644
index 0000000000..ad0199c058
--- /dev/null
+++ b/drivers/mux/Kconfig
@@ -0,0 +1,7 @@ 
+menu "Multiplexer drivers"
+
+config MULTIPLEXER
+	bool "Multiplexer Support"
+	depends on DM
+
+endmenu
diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
new file mode 100644
index 0000000000..351e4363d3
--- /dev/null
+++ b/drivers/mux/Makefile
@@ -0,0 +1,6 @@ 
+# SPDX-License-Identifier: GPL-2.0+
+#
+# (C) Copyright 2019
+# Jean-Jacques Hiblot <jjhiblot@ti.com>
+
+obj-$(CONFIG_$(SPL_)MULTIPLEXER) += mux-uclass.o
diff --git a/drivers/mux/mux-uclass.c b/drivers/mux/mux-uclass.c
new file mode 100644
index 0000000000..58998af29c
--- /dev/null
+++ b/drivers/mux/mux-uclass.c
@@ -0,0 +1,296 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Multiplexer subsystem
+ *
+ * Based on the linux multiplexer framework
+ *
+ * Copyright (C) 2017 Axentia Technologies AB
+ * Author: Peter Rosin <peda@axentia.se>
+ *
+ * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
+ * Jean-Jacques Hiblot <jjhiblot@ti.com>
+ */
+
+#include <common.h>
+#include <mux-internal.h>
+#include <dm.h>
+#include <dt-structs.h>
+#include <errno.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <dm/read.h>
+#include <dt-bindings/mux/mux.h>
+
+/*
+ * The idle-as-is "state" is not an actual state that may be selected, it
+ * only implies that the state should not be changed. So, use that state
+ * as indication that the cached state of the multiplexer is unknown.
+ */
+#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS
+
+static inline const struct mux_control_ops *mux_dev_ops(struct udevice *dev)
+{
+	return (const struct mux_control_ops *)dev->driver->ops;
+}
+
+static int mux_control_set(struct mux_control *mux, int state)
+{
+	int ret = mux_dev_ops(mux->dev)->set(mux, state);
+
+	mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;
+
+	return ret;
+}
+
+unsigned int mux_control_states(struct mux_control *mux)
+{
+	return mux->states;
+}
+
+static int __mux_control_select(struct mux_control *mux, int state)
+{
+	int ret;
+
+	if (WARN_ON(state < 0 || state >= mux->states))
+		return -EINVAL;
+
+	if (mux->cached_state == state)
+		return 0;
+
+	ret = mux_control_set(mux, state);
+	if (ret >= 0)
+		return 0;
+
+	/* The mux update failed, try to revert if appropriate... */
+	if (mux->idle_state != MUX_IDLE_AS_IS)
+		mux_control_set(mux, mux->idle_state);
+
+	return ret;
+}
+
+int mux_control_select(struct mux_control *mux, unsigned int state)
+{
+	int ret;
+
+	if (mux->in_use)
+		return -EBUSY;
+
+	ret = __mux_control_select(mux, state);
+
+	if (ret < 0)
+		return ret;
+
+	mux->in_use = true;
+
+	return 0;
+}
+
+int mux_control_deselect(struct mux_control *mux)
+{
+	int ret = 0;
+
+	if (mux->idle_state != MUX_IDLE_AS_IS &&
+	    mux->idle_state != mux->cached_state)
+		ret = mux_control_set(mux, mux->idle_state);
+
+	mux->in_use = false;
+
+	return ret;
+}
+
+static int mux_of_xlate_default(struct mux_chip *mux_chip,
+				struct ofnode_phandle_args *args,
+				struct mux_control **muxp)
+{
+	struct mux_control *mux;
+	int id;
+
+	debug("%s(mux=%p)\n", __func__, mux);
+
+	if (args->args_count > 1) {
+		debug("Invaild args_count: %d\n", args->args_count);
+		return -EINVAL;
+	}
+
+	if (args->args_count)
+		id = args->args[0];
+	else
+		id = 0;
+
+	if (id >= mux_chip->controllers) {
+		dev_err(dev, "bad mux controller %u specified in %s\n",
+			id, ofnode_get_name(args->node));
+		return -ERANGE;
+	}
+
+	mux = &mux_chip->mux[id];
+	mux->id = id;
+	*muxp = mux;
+	return 0;
+}
+
+static int mux_get_by_indexed_prop(struct udevice *dev, const char *prop_name,
+				   int index, struct mux_control **mux)
+{
+	int ret;
+	struct ofnode_phandle_args args;
+	struct udevice *dev_mux;
+	const struct mux_control_ops *ops;
+	struct mux_chip *mux_chip;
+
+	debug("%s(dev=%p, index=%d, mux=%p)\n", __func__, dev, index, mux);
+
+	ret = dev_read_phandle_with_args(dev, prop_name, "#mux-control-cells",
+					 0, index, &args);
+	if (ret) {
+		debug("%s: fdtdec_parse_phandle_with_args failed: err=%d\n",
+		      __func__, ret);
+		return ret;
+	}
+
+	ret = uclass_get_device_by_ofnode(UCLASS_MUX, args.node, &dev_mux);
+	if (ret) {
+		debug("%s: uclass_get_device_by_ofnode failed: err=%d\n",
+		      __func__, ret);
+		return ret;
+	}
+
+	mux_chip = dev_get_uclass_priv(dev_mux);
+
+	ops = mux_dev_ops(dev_mux);
+	if (ops->of_xlate)
+		ret = ops->of_xlate(mux_chip, &args, mux);
+	else
+		ret = mux_of_xlate_default(mux_chip, &args, mux);
+	if (ret) {
+		debug("of_xlate() failed: %d\n", ret);
+		return ret;
+	}
+	(*mux)->dev = dev_mux;
+
+	return 0;
+}
+
+int mux_get_by_index(struct udevice *dev, int index, struct mux_control **mux)
+{
+	return mux_get_by_indexed_prop(dev, "mux-controls", index, mux);
+}
+
+int mux_control_get(struct udevice *dev, const char *name,
+		    struct mux_control **mux)
+{
+	int index;
+
+	debug("%s(dev=%p, name=%s, mux=%p)\n", __func__, dev, name, mux);
+
+	index = dev_read_stringlist_search(dev, "mux-control-names", name);
+	if (index < 0) {
+		debug("fdt_stringlist_search() failed: %d\n", index);
+		return index;
+	}
+
+	return mux_get_by_index(dev, index, mux);
+}
+
+void mux_control_put(struct mux_control *mux)
+{
+	mux_control_deselect(mux);
+}
+
+static void devm_mux_control_release(struct udevice *dev, void *res)
+{
+	mux_control_put(*(struct mux_control **)res);
+}
+
+struct mux_control *devm_mux_control_get(struct udevice *dev, const char *id)
+{
+	int rc;
+	struct mux_control **mux;
+
+	mux = devres_alloc(devm_mux_control_release,
+			   sizeof(struct mux_control *), __GFP_ZERO);
+	if (unlikely(!mux))
+		return ERR_PTR(-ENOMEM);
+
+	rc = mux_control_get(dev, id, mux);
+	if (rc)
+		return ERR_PTR(rc);
+
+	devres_add(dev, mux);
+	return *mux;
+}
+
+int mux_alloc_controllers(struct udevice *dev, unsigned int controllers)
+{
+	int i;
+	struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
+
+	mux_chip->mux = devm_kmalloc(dev,
+				     sizeof(struct mux_control) * controllers,
+				     __GFP_ZERO);
+	if (!mux_chip->mux)
+		return -ENOMEM;
+
+	mux_chip->controllers = controllers;
+
+	for (i = 0; i < mux_chip->controllers; ++i) {
+		struct mux_control *mux = &mux_chip->mux[i];
+
+		mux->dev = dev;
+		mux->cached_state = MUX_CACHE_UNKNOWN;
+		mux->idle_state = MUX_IDLE_AS_IS;
+		mux->in_use = false;
+		mux->id = i;
+	}
+
+	return 0;
+}
+
+int mux_uclass_post_probe(struct udevice *dev)
+{
+	int i, ret;
+	struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
+
+	for (i = 0; i < mux_chip->controllers; ++i) {
+		struct mux_control *mux = &mux_chip->mux[i];
+
+		if (mux->idle_state == mux->cached_state)
+			continue;
+
+		ret = mux_control_set(mux, mux->idle_state);
+		if (ret < 0) {
+			dev_err(&mux_chip->dev, "unable to set idle state\n");
+			return ret;
+		}
+	}
+	return 0;
+}
+
+void dm_mux_init(void)
+{
+	struct uclass *uc;
+	struct udevice *dev;
+	int ret;
+
+	ret = uclass_get(UCLASS_MUX, &uc);
+	if (ret < 0) {
+		debug("unable to get MUX uclass\n");
+		return;
+	}
+	uclass_foreach_dev(dev, uc) {
+		if (dev_read_bool(dev, "u-boot,mux-autoprobe")) {
+			ret = device_probe(dev);
+			if (ret)
+				debug("unable to probe device %s\n", dev->name);
+		} else {
+			printf("not found for dev %s\n", dev->name);
+		}
+	}
+}
+
+UCLASS_DRIVER(mux) = {
+	.id		= UCLASS_MUX,
+	.name		= "mux",
+	.post_probe	= mux_uclass_post_probe,
+	.per_device_auto_alloc_size = sizeof(struct mux_chip),
+};
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index d4d96106b3..869c0616bd 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -64,6 +64,7 @@  enum uclass_id {
 	UCLASS_MMC,		/* SD / MMC card or chip */
 	UCLASS_MOD_EXP,		/* RSA Mod Exp device */
 	UCLASS_MTD,		/* Memory Technology Device (MTD) device */
+	UCLASS_MUX,		/* Multiplexer device */
 	UCLASS_NOP,		/* No-op devices */
 	UCLASS_NORTHBRIDGE,	/* Intel Northbridge / SDRAM controller */
 	UCLASS_NVME,		/* NVM Express device */
diff --git a/include/dt-bindings/mux/mux.h b/include/dt-bindings/mux/mux.h
new file mode 100644
index 0000000000..042719218d
--- /dev/null
+++ b/include/dt-bindings/mux/mux.h
@@ -0,0 +1,17 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * This header provides constants for most Multiplexer bindings.
+ *
+ * Most Multiplexer bindings specify an idle state. In most cases, the
+ * the multiplexer can be left as is when idle, and in some cases it can
+ * disconnect the input/output and leave the multiplexer in a high
+ * impedance state.
+ */
+
+#ifndef _DT_BINDINGS_MUX_MUX_H
+#define _DT_BINDINGS_MUX_MUX_H
+
+#define MUX_IDLE_AS_IS      (-1)
+#define MUX_IDLE_DISCONNECT (-2)
+
+#endif
diff --git a/include/mux-internal.h b/include/mux-internal.h
new file mode 100644
index 0000000000..63444f4c3d
--- /dev/null
+++ b/include/mux-internal.h
@@ -0,0 +1,80 @@ 
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Based on the linux multiplexer framework
+ *
+ * Copyright (C) 2017 Axentia Technologies AB
+ * Author: Peter Rosin <peda@axentia.se>
+ *
+ * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
+ * Jean-Jacques Hiblot <jjhiblot@ti.com>
+ */
+
+#ifndef _MUX_UCLASS_H
+#define _MUX_UCLASS_H
+
+/* See mux.h for background documentation. */
+
+#include <mux.h>
+
+struct ofnode_phandle_args;
+
+/**
+ * struct mux_chip -	Represents a chip holding mux controllers.
+ * @controllers:	Number of mux controllers handled by the chip.
+ * @mux:		Array of mux controllers that are handled.
+ * @dev:		Device structure.
+ * @ops:		Mux controller operations.
+ */
+struct mux_chip {
+	unsigned int controllers;
+	struct mux_control *mux;
+};
+
+/**
+ * struct mux_control_ops -	Mux controller operations for a mux chip.
+ * @set:			Set the state of the given mux controller.
+ */
+struct mux_control_ops {
+	int (*set)(struct mux_control *mux, int state);
+	int (*of_xlate)(struct mux_chip *dev_mux,
+			struct ofnode_phandle_args *args,
+			struct mux_control **mux);
+};
+
+/**
+ * struct mux_control -	Represents a mux controller.
+ * @chip:		The mux chip that is handling this mux controller.
+ * @cached_state:	The current mux controller state, or -1 if none.
+ * @states:		The number of mux controller states.
+ * @idle_state:		The mux controller state to use when inactive, or one
+ *			of MUX_IDLE_AS_IS and MUX_IDLE_DISCONNECT.
+ *
+ * Mux drivers may only change @states and @idle_state, and may only do so
+ * between allocation and registration of the mux controller. Specifically,
+ * @cached_state is internal to the mux core and should never be written by
+ * mux drivers.
+ */
+struct mux_control {
+	bool	in_use;
+	struct udevice *dev;
+	int cached_state;
+	unsigned int states;
+	int idle_state;
+	int id;
+};
+
+/**
+ * mux_control_get_index() - Get the index of the given mux controller
+ * @mux: The mux-control to get the index for.
+ *
+ * Return: The index of the mux controller within the mux chip the mux
+ * controller is a part of.
+ */
+static inline unsigned int mux_control_get_index(struct mux_control *mux)
+{
+	return mux->id;
+}
+
+int mux_alloc_controllers(struct udevice *dev, unsigned int controllers);
+
+#endif
diff --git a/include/mux.h b/include/mux.h
new file mode 100644
index 0000000000..d9d7728fea
--- /dev/null
+++ b/include/mux.h
@@ -0,0 +1,114 @@ 
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Based on the linux multiplexer framework
+ *
+ * Copyright (C) 2017 Axentia Technologies AB
+ * Author: Peter Rosin <peda@axentia.se>
+ *
+ * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
+ * Jean-Jacques Hiblot <jjhiblot@ti.com>
+ */
+
+#ifndef _MUX_H_
+#define _MUX_H_
+
+#include <linux/errno.h>
+#include <linux/types.h>
+
+struct udevice;
+struct mux_control;
+
+#if CONFIG_IS_ENABLED(MULTIPLEXER)
+/**
+ * mux_control_states() - Query the number of multiplexer states.
+ * @mux: The mux-control to query.
+ *
+ * Return: The number of multiplexer states.
+ */
+unsigned int mux_control_states(struct mux_control *mux);
+
+/**
+ * mux_control_select() - Select the given multiplexer state.
+ * @mux: The mux-control to request a change of state from.
+ * @state: The new requested state.
+ *
+ * On successfully selecting the mux-control state, it will be locked until
+ * there is a call to mux_control_deselect(). If the mux-control is already
+ * selected when mux_control_select() is called, the function will indicate
+ * -EBUSY
+ *
+ * Therefore, make sure to call mux_control_deselect() when the operation is
+ * complete and the mux-control is free for others to use, but do not call
+ * mux_control_deselect() if mux_control_select() fails.
+ *
+ * Return: 0 when the mux-control state has the requested state or a negative
+ * errno on error.
+ */
+int __must_check mux_control_select(struct mux_control *mux,
+				    unsigned int state);
+#define mux_control_try_select(mux) mux_control_select(mux)
+
+/**
+ * mux_control_deselect() - Deselect the previously selected multiplexer state.
+ * @mux: The mux-control to deselect.
+ *
+ * It is required that a single call is made to mux_control_deselect() for
+ * each and every successful call made to either of mux_control_select() or
+ * mux_control_try_select().
+ *
+ * Return: 0 on success and a negative errno on error. An error can only
+ * occur if the mux has an idle state. Note that even if an error occurs, the
+ * mux-control is unlocked and is thus free for the next access.
+ */
+int mux_control_deselect(struct mux_control *mux);
+
+int mux_get_by_index(struct udevice *dev, int index, struct mux_control **mux);
+int mux_control_get(struct udevice *dev, const char *name,
+		    struct mux_control **mux);
+
+void mux_control_put(struct mux_control *mux);
+
+struct mux_control *devm_mux_control_get(struct udevice *dev,
+					 const char *mux_name);
+
+void dm_mux_init(void);
+#else
+unsigned int mux_control_states(struct mux_control *mux)
+{
+	return -ENOSYS;
+}
+
+int __must_check mux_control_select(struct mux_control *mux,
+				    unsigned int state)
+{
+	return -ENOSYS;
+}
+
+#define mux_control_try_select(mux) mux_control_select(mux)
+
+int mux_control_deselect(struct mux_control *mux)
+{
+	return -ENOSYS;
+}
+
+struct mux_control *mux_control_get(struct udevice *dev, const char *mux_name)
+{
+	return NULL;
+}
+
+void mux_control_put(struct mux_control *mux)
+{
+}
+
+struct mux_control *devm_mux_control_get(struct udevice *dev,
+					 const char *mux_name)
+{
+	return NULL;
+}
+
+void dm_mux_init(void)
+{
+}
+#endif
+
+#endif