diff mbox series

[v9,2/5] PCI: Add Loongson PCI Controller support

Message ID 20200512074413.3557835-2-jiaxun.yang@flygoat.com
State New
Headers show
Series [v9,1/5] PCI: Don't disable decoding when mmio_always_on is set | expand

Commit Message

Jiaxun Yang May 12, 2020, 7:43 a.m. UTC 
This controller can be found on Loongson-2K SoC, Loongson-3
systems with RS780E/LS7A PCH.

The RS780E part of code was previously located at
arch/mips/pci/ops-loongson3.c and now it can use generic PCI
driver implementation.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Reviewed-by: Rob Herring <robh@kernel.org>

--
v2:
	- Clean up according to rob's suggestions
	- Claim that it can't work as a module
v3:
	- Fix a typo
v4:
	- More clean-ups: Drop flag check, use devfn
v7:
	- Fix ordering according to huacai's suggestion
v8:
	- Style clean and bugfix according to Bjorn's review
v9:
	- Confirm with vendor about the details on system_bus BARs
	- Further cleanups
	- I think assume root_bus as 0 simplify our code a lot, as that's
		always valid to the hardware, as we're not ecam or dwc, we can't
		easily get host bus_nr via cfg, adding that will cause unnecessary
		overhead.
---
 drivers/pci/controller/Kconfig        |  10 +
 drivers/pci/controller/Makefile       |   1 +
 drivers/pci/controller/pci-loongson.c | 251 ++++++++++++++++++++++++++
 3 files changed, 262 insertions(+)
 create mode 100644 drivers/pci/controller/pci-loongson.c

Comments

Bjorn Helgaas May 12, 2020, 6:06 p.m. UTC | #1 
On Tue, May 12, 2020 at 03:43:56PM +0800, Jiaxun Yang wrote:
> This controller can be found on Loongson-2K SoC, Loongson-3
> systems with RS780E/LS7A PCH.
> 
> The RS780E part of code was previously located at
> arch/mips/pci/ops-loongson3.c and now it can use generic PCI
> driver implementation.
> 
> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> Reviewed-by: Rob Herring <robh@kernel.org>

> +static void system_bus_quirk(struct pci_dev *pdev)
> +{
> +	u16 tmp;
> +
> +	/* 
> +	 * These devices are not sharing resouces with rest of devices
> +	 * on host bus and firmware will ensure their BARs are placed
> +	 * in safe ranges. Also there might be some config registers
> +	 * in their config space so kernel shouldn't ignore them.

"Firmware ensuring BARs are placed in 'safe' ranges" is not a
sufficient answer.  As I said before, Linux needs to know both the
ADDRESS and the SIZE of whatever non-standard BARs these are.
Otherwise, we're liable to assign that space to a different device.

If you have to hard-code the size, so be it.  That would mean the
hardware is completely broken, but at least we could make Linux deal
with it.  If the hardware consumes address space we don't know about,
we can't deal with that.

> +	 */
> +	pdev->mmio_always_on = 1;
> +	pdev->non_compliant_bars = 1;
> +}

> +void __iomem *pci_loongson_map_bus(struct pci_bus *bus, unsigned int devfn,
> +			       int where)
> +{
> +	unsigned char busnum = bus->number;
> +	struct pci_host_bridge *bridge = pci_find_host_bridge(bus);
> +	struct loongson_pci *priv =  pci_host_bridge_priv(bridge);
> +
> +	/*
> +	 * Do not read more than one device on the bus other than
> +	 * the host bus 0.
> +	 */

If the hardware is restricted such that the root bus number must be
zero, pleae say that explicitly here.  Otherwise, it just looks like
a bug.

> +	if (priv->flags & FLAG_DEV_FIX && busnum != 0 &&
> +		PCI_SLOT(devfn) > 0)
> +		return NULL;
> +
> +	/* CFG0 can only access standard space */
> +	if (where < PCI_CFG_SPACE_SIZE && priv->cfg0_base)
> +		return cfg0_map(priv, busnum, devfn, where);
> +
> +	/* CFG1 can access extended space */
> +	if (where < PCI_CFG_SPACE_EXP_SIZE && priv->cfg1_base)
> +		return cfg1_map(priv, busnum, devfn, where);
> +
> +	return NULL;
> +}
Jiaxun Yang May 13, 2020, 1:20 a.m. UTC | #2 
于 2020年5月13日 GMT+08:00 上午2:06:02, Bjorn Helgaas <helgaas@kernel.org> 写到:
>On Tue, May 12, 2020 at 03:43:56PM +0800, Jiaxun Yang wrote:
>> This controller can be found on Loongson-2K SoC, Loongson-3
>> systems with RS780E/LS7A PCH.
>> 
>> The RS780E part of code was previously located at
>> arch/mips/pci/ops-loongson3.c and now it can use generic PCI
>> driver implementation.
>> 
>> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
>> Reviewed-by: Rob Herring <robh@kernel.org>
>
>> +static void system_bus_quirk(struct pci_dev *pdev)
>> +{
>> +	u16 tmp;
>> +
>> +	/* 
>> +	 * These devices are not sharing resouces with rest of devices
>> +	 * on host bus and firmware will ensure their BARs are placed
>> +	 * in safe ranges. Also there might be some config registers
>> +	 * in their config space so kernel shouldn't ignore them.
>
>"Firmware ensuring BARs are placed in 'safe' ranges" is not a
>sufficient answer.  As I said before, Linux needs to know both the
>ADDRESS and the SIZE of whatever non-standard BARs these are.
>Otherwise, we're liable to assign that space to a different device.

The address assigned to these devices will never be a part of resources
belongs to the host bridge. That's enforced by hardware and firmware,
so address conflict would never happen.

I'm doing like this to ensure kernel will discover this device but do nothing
about assignment of resources to it.

>
>If you have to hard-code the size, so be it.  That would mean the
>hardware is completely broken, but at least we could make Linux deal
>with it.  If the hardware consumes address space we don't know about,
>we can't deal with that.
>
>> +	 */
>> +	pdev->mmio_always_on = 1;
>> +	pdev->non_compliant_bars = 1;
>> +}
>
>> +void __iomem *pci_loongson_map_bus(struct pci_bus *bus, unsigned int devfn,
>> +			       int where)
>> +{
>> +	unsigned char busnum = bus->number;
>> +	struct pci_host_bridge *bridge = pci_find_host_bridge(bus);
>> +	struct loongson_pci *priv =  pci_host_bridge_priv(bridge);
>> +
>> +	/*
>> +	 * Do not read more than one device on the bus other than
>> +	 * the host bus 0.
>> +	 */
>
>If the hardware is restricted such that the root bus number must be
>zero, pleae say that explicitly here.  Otherwise, it just looks like
>a bug.
>
>> +	if (priv->flags & FLAG_DEV_FIX && busnum != 0 &&
>> +		PCI_SLOT(devfn) > 0)
>> +		return NULL;
>> +
>> +	/* CFG0 can only access standard space */
>> +	if (where < PCI_CFG_SPACE_SIZE && priv->cfg0_base)
>> +		return cfg0_map(priv, busnum, devfn, where);
>> +
>> +	/* CFG1 can access extended space */
>> +	if (where < PCI_CFG_SPACE_EXP_SIZE && priv->cfg1_base)
>> +		return cfg1_map(priv, busnum, devfn, where);
>> +
>> +	return NULL;
>> +}
Bjorn Helgaas May 13, 2020, 3:05 p.m. UTC | #3 
On Wed, May 13, 2020 at 09:20:08AM +0800, Jiaxun Yang wrote:
> 于 2020年5月13日 GMT+08:00 上午2:06:02, Bjorn Helgaas <helgaas@kernel.org> 写到:
> >On Tue, May 12, 2020 at 03:43:56PM +0800, Jiaxun Yang wrote:
> >> This controller can be found on Loongson-2K SoC, Loongson-3
> >> systems with RS780E/LS7A PCH.
> >> 
> >> The RS780E part of code was previously located at
> >> arch/mips/pci/ops-loongson3.c and now it can use generic PCI
> >> driver implementation.
> >> 
> >> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> >> Reviewed-by: Rob Herring <robh@kernel.org>
> >
> >> +static void system_bus_quirk(struct pci_dev *pdev)
> >> +{
> >> +	u16 tmp;
> >> +
> >> +	/* 
> >> +	 * These devices are not sharing resouces with rest of devices
> >> +	 * on host bus and firmware will ensure their BARs are placed
> >> +	 * in safe ranges. Also there might be some config registers
> >> +	 * in their config space so kernel shouldn't ignore them.
> >
> >"Firmware ensuring BARs are placed in 'safe' ranges" is not a
> >sufficient answer.  As I said before, Linux needs to know both the
> >ADDRESS and the SIZE of whatever non-standard BARs these are.
> >Otherwise, we're liable to assign that space to a different device.
> 
> The address assigned to these devices will never be a part of resources
> belongs to the host bridge. That's enforced by hardware and firmware,
> so address conflict would never happen.
> 
> I'm doing like this to ensure kernel will discover this device but do nothing
> about assignment of resources to it.

OK, that's really ugly, but I guess we can't do anything about it.  It
would be helpful to make the comment say something like:

  The address space consumed by these devices is outside the resources
  of the host bridge.

Side note: in ACPI systems, the ACPI namespace is supposed to describe
all resources consumed by all devices.  Does DT have a similar
expectation?  Is there something in DT that tells us about the address
space used by these devices?  Even if that space never overlaps with
the PCI host bridge apertures, it might be useful to show the space in
/proc/iomem and similar places.

Bjorn
diff mbox series

Patch

diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
index 91bfdb784829..ae36edb1d7db 100644
--- a/drivers/pci/controller/Kconfig
+++ b/drivers/pci/controller/Kconfig
@@ -258,6 +258,16 @@  config PCI_HYPERV_INTERFACE
 	  The Hyper-V PCI Interface is a helper driver allows other drivers to
 	  have a common interface with the Hyper-V PCI frontend driver.
 
+config PCI_LOONGSON
+	bool "LOONGSON PCI Controller"
+	depends on MACH_LOONGSON64 || COMPILE_TEST
+	depends on OF
+	depends on PCI_QUIRKS
+	default MACH_LOONGSON64
+	help
+	  Say Y here if you want to enable PCI controller support on
+	  Loongson systems.
+
 source "drivers/pci/controller/dwc/Kconfig"
 source "drivers/pci/controller/mobiveil/Kconfig"
 source "drivers/pci/controller/cadence/Kconfig"
diff --git a/drivers/pci/controller/Makefile b/drivers/pci/controller/Makefile
index 158c59771824..fbac4b0190a0 100644
--- a/drivers/pci/controller/Makefile
+++ b/drivers/pci/controller/Makefile
@@ -28,6 +28,7 @@  obj-$(CONFIG_PCIE_MEDIATEK) += pcie-mediatek.o
 obj-$(CONFIG_PCIE_TANGO_SMP8759) += pcie-tango.o
 obj-$(CONFIG_VMD) += vmd.o
 obj-$(CONFIG_PCIE_BRCMSTB) += pcie-brcmstb.o
+obj-$(CONFIG_PCI_LOONGSON) += pci-loongson.o
 # pcie-hisi.o quirks are needed even without CONFIG_PCIE_DW
 obj-y				+= dwc/
 obj-y				+= mobiveil/
diff --git a/drivers/pci/controller/pci-loongson.c b/drivers/pci/controller/pci-loongson.c
new file mode 100644
index 000000000000..7673e85f9200
--- /dev/null
+++ b/drivers/pci/controller/pci-loongson.c
@@ -0,0 +1,251 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Loongson PCI Host Controller Driver
+ *
+ * Copyright (C) 2020 Jiaxun Yang <jiaxun.yang@flygoat.com>
+ */
+
+#include <linux/of_device.h>
+#include <linux/of_pci.h>
+#include <linux/pci.h>
+#include <linux/pci_ids.h>
+
+#include "../pci.h"
+
+/* Device IDs */
+#define DEV_PCIE_PORT_0	0x7a09
+#define DEV_PCIE_PORT_1	0x7a19
+#define DEV_PCIE_PORT_2	0x7a29
+
+#define DEV_LS2K_APB	0x7a02
+#define DEV_LS7A_CONF	0x7a10
+#define DEV_LS7A_LPC	0x7a0c
+
+#define FLAG_CFG0	BIT(0)
+#define FLAG_CFG1	BIT(1)
+#define FLAG_DEV_FIX	BIT(2)
+
+struct loongson_pci {
+	void __iomem *cfg0_base;
+	void __iomem *cfg1_base;
+	struct platform_device *pdev;
+	u32 flags;
+};
+
+/* Fixup wrong class code in PCIe bridges */
+static void bridge_class_quirk(struct pci_dev *dev)
+{
+	dev->class = PCI_CLASS_BRIDGE_PCI << 8;
+}
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LOONGSON,
+			DEV_PCIE_PORT_0, bridge_class_quirk);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LOONGSON,
+			DEV_PCIE_PORT_1, bridge_class_quirk);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LOONGSON,
+			DEV_PCIE_PORT_2, bridge_class_quirk);
+
+static void system_bus_quirk(struct pci_dev *pdev)
+{
+	u16 tmp;
+
+	/* 
+	 * These devices are not sharing resouces with rest of devices
+	 * on host bus and firmware will ensure their BARs are placed
+	 * in safe ranges. Also there might be some config registers
+	 * in their config space so kernel shouldn't ignore them.
+	 */
+	pdev->mmio_always_on = 1;
+	pdev->non_compliant_bars = 1;
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON,
+			DEV_LS2K_APB, system_bus_quirk);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON,
+			DEV_LS7A_CONF, system_bus_quirk);
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_LOONGSON,
+			DEV_LS7A_LPC, system_bus_quirk);
+
+static void loongson_mrrs_quirk(struct pci_dev *dev)
+{
+	struct pci_bus *bus = dev->bus;
+	struct pci_dev *bridge;
+	static const struct pci_device_id bridge_devids[] = {
+		{ PCI_VDEVICE(LOONGSON, DEV_PCIE_PORT_0) },
+		{ PCI_VDEVICE(LOONGSON, DEV_PCIE_PORT_1) },
+		{ PCI_VDEVICE(LOONGSON, DEV_PCIE_PORT_2) },
+		{ 0, },
+	};
+
+	/* look for the matching bridge */
+	while (!pci_is_root_bus(bus)) {
+		bridge = bus->self;
+		bus = bus->parent;
+		/*
+		 * Some Loongson PCIe ports have a h/w limitation of
+		 * 256 bytes maximum read request size. They can't handle
+		 * anything larger than this. So force this limit on
+		 * any devices attached under these ports.
+		 */
+		if (pci_match_id(bridge_devids, bridge)) {
+			if (pcie_get_readrq(dev) > 256) {
+				pci_info(dev, "limiting MRRS to 256\n");
+				pcie_set_readrq(dev, 256);
+			}
+			break;
+		}
+	}
+}
+DECLARE_PCI_FIXUP_ENABLE(PCI_ANY_ID, PCI_ANY_ID, loongson_mrrs_quirk);
+
+static void __iomem *cfg1_map(struct loongson_pci *priv, int bus,
+				unsigned int devfn, int where)
+{
+	unsigned long addroff = 0x0;
+
+	if (bus != 0)
+		addroff |= BIT(28); /* Type 1 Access */
+	addroff |= (where & 0xff) | ((where & 0xf00) << 16);
+	addroff |= (bus << 16) | (devfn << 8);
+	return priv->cfg1_base + addroff;
+}
+
+static void __iomem *cfg0_map(struct loongson_pci *priv, int bus,
+				unsigned int devfn, int where)
+{
+	unsigned long addroff = 0x0;
+
+	if (bus != 0)
+		addroff |= BIT(24); /* Type 1 Access */
+	addroff |= (bus << 16) | (devfn << 8) | where;
+	return priv->cfg0_base + addroff;
+}
+
+void __iomem *pci_loongson_map_bus(struct pci_bus *bus, unsigned int devfn,
+			       int where)
+{
+	unsigned char busnum = bus->number;
+	struct pci_host_bridge *bridge = pci_find_host_bridge(bus);
+	struct loongson_pci *priv =  pci_host_bridge_priv(bridge);
+
+	/*
+	 * Do not read more than one device on the bus other than
+	 * the host bus 0.
+	 */
+	if (priv->flags & FLAG_DEV_FIX && busnum != 0 &&
+		PCI_SLOT(devfn) > 0)
+		return NULL;
+
+	/* CFG0 can only access standard space */
+	if (where < PCI_CFG_SPACE_SIZE && priv->cfg0_base)
+		return cfg0_map(priv, busnum, devfn, where);
+
+	/* CFG1 can access extended space */
+	if (where < PCI_CFG_SPACE_EXP_SIZE && priv->cfg1_base)
+		return cfg1_map(priv, busnum, devfn, where);
+
+	return NULL;
+}
+
+static int loongson_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
+{
+	int irq;
+	u8 val;
+
+	irq = of_irq_parse_and_map_pci(dev, slot, pin);
+	if (irq > 0)
+		return irq;
+
+	/* Care i8259 legacy systems */
+	pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &val);
+	/* i8259 only have 15 IRQs */
+	if (val > 15)
+		return 0;
+
+	return val;
+}
+
+/* H/w only accept 32-bit PCI operations */
+static struct pci_ops loongson_pci_ops = {
+	.map_bus = pci_loongson_map_bus,
+	.read	= pci_generic_config_read32,
+	.write	= pci_generic_config_write32,
+};
+
+static const struct of_device_id loongson_pci_of_match[] = {
+	{ .compatible = "loongson,ls2k-pci",
+		.data = (void *)(FLAG_CFG0 | FLAG_CFG1 | FLAG_DEV_FIX), },
+	{ .compatible = "loongson,ls7a-pci",
+		.data = (void *)(FLAG_CFG0 | FLAG_CFG1 | FLAG_DEV_FIX), },
+	{ .compatible = "loongson,rs780e-pci",
+		.data = (void *)(FLAG_CFG0), },
+	{}
+};
+
+static int loongson_pci_probe(struct platform_device *pdev)
+{
+	struct loongson_pci *priv;
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node;
+	struct pci_host_bridge *bridge;
+	struct resource *regs;
+	int err;
+
+	if (!node)
+		return -ENODEV;
+
+	bridge = devm_pci_alloc_host_bridge(dev, sizeof(*priv));
+	if (!bridge)
+		return -ENODEV;
+
+	priv = pci_host_bridge_priv(bridge);
+	priv->pdev = pdev;
+	priv->flags = (unsigned long)of_device_get_match_data(dev);
+
+	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!regs) {
+		dev_err(dev, "missing mem resources for cfg0\n");
+		return -EINVAL;
+	}
+
+	priv->cfg0_base = devm_pci_remap_cfg_resource(dev, regs);
+	if (IS_ERR(priv->cfg0_base))
+		return PTR_ERR(priv->cfg0_base);
+
+	/* CFG1 is optional */
+	if (priv->flags & FLAG_CFG1) {
+		regs = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+		if (!regs)
+			dev_info(dev, "missing mem resource for cfg1\n");
+		else {
+			priv->cfg1_base = devm_pci_remap_cfg_resource(dev, regs);
+			if (IS_ERR(priv->cfg1_base))
+				priv->cfg1_base = NULL;
+		}
+	}
+
+	err = pci_parse_request_of_pci_ranges(dev, &bridge->windows,
+						&bridge->dma_ranges, NULL);
+	if (err) {
+		dev_err(dev, "failed to get bridge resources\n");
+		return err;
+	}
+
+	bridge->dev.parent = dev;
+	bridge->sysdata = priv;
+	bridge->ops = &loongson_pci_ops;
+	bridge->map_irq = loongson_map_irq;
+
+	err = pci_host_probe(bridge);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static struct platform_driver loongson_pci_driver = {
+	.driver = {
+		.name = "loongson-pci",
+		.of_match_table = loongson_pci_of_match,
+	},
+	.probe = loongson_pci_probe,
+};
+builtin_platform_driver(loongson_pci_driver);