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Commit 0d9a693c authored by Mika Westerberg's avatar Mika Westerberg Committed by Rafael J. Wysocki
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gpio / ACPI: Add support for _DSD device properties 



With release of ACPI 5.1 and _DSD method we can finally name GPIOs (and
other things as well) returned by _CRS. Previously we were only able to
use integer index to find the corresponding GPIO, which is pretty error
prone if the order changes.

With _DSD we can now query GPIOs using name instead of an integer index,
like the below example shows:

  // Bluetooth device with reset and shutdown GPIOs
  Device (BTH)
  {
      Name (_HID, ...)

      Name (_CRS, ResourceTemplate ()
      {
          GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
                  "\\_SB.GPO0", 0, ResourceConsumer) {15}
          GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
                  "\\_SB.GPO0", 0, ResourceConsumer) {27, 31}
      })

      Name (_DSD, Package ()
      {
          ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
          Package ()
	  {
              Package () {"reset-gpio", Package() {^BTH, 1, 1, 0 }},
              Package () {"shutdown-gpio", Package() {^BTH, 0, 0, 0 }},
          }
      })
  }

The format of the supported GPIO property is:

  Package () { "name", Package () { ref, index, pin, active_low }}

  ref - The device that has _CRS containing GpioIo()/GpioInt() resources,
        typically this is the device itself (BTH in our case).
  index - Index of the GpioIo()/GpioInt() resource in _CRS starting from zero.
  pin - Pin in the GpioIo()/GpioInt() resource. Typically this is zero.
  active_low - If 1 the GPIO is marked as active_low.

Since ACPI GpioIo() resource does not have field saying whether it is
active low or high, the "active_low" argument can be used here. Setting
it to 1 marks the GPIO as active low.

In our Bluetooth example the "reset-gpio" refers to the second GpioIo()
resource, second pin in that resource with the GPIO number of 31.

This patch implements necessary support to gpiolib for extracting GPIOs
using _DSD device properties.

Signed-off-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Acked-by: default avatarGrant Likely <grant.likely@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent f60e7074

Documentation/acpi/gpio-properties.txt

0 → 100644
+52 −0
Original line number Diff line number Diff line 
_DSD Device Properties Related to GPIO

--------------------------------------



With the release of ACPI 5.1 and the _DSD configuration objecte names

can finally be given to GPIOs (and other things as well) returned by

_CRS.  Previously, we were only able to use an integer index to find

the corresponding GPIO, which is pretty error prone (it depends on

the _CRS output ordering, for example).



With _DSD we can now query GPIOs using a name instead of an integer

index, like the ASL example below shows:



  // Bluetooth device with reset and shutdown GPIOs

  Device (BTH)

  {

      Name (_HID, ...)



      Name (_CRS, ResourceTemplate ()

      {

          GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,

                  "\\_SB.GPO0", 0, ResourceConsumer) {15}

          GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,

                  "\\_SB.GPO0", 0, ResourceConsumer) {27, 31}

      })



      Name (_DSD, Package ()

      {

          ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),

          Package ()

	  {

              Package () {"reset-gpio", Package() {^BTH, 1, 1, 0 }},

              Package () {"shutdown-gpio", Package() {^BTH, 0, 0, 0 }},

          }

      })

  }



The format of the supported GPIO property is:



  Package () { "name", Package () { ref, index, pin, active_low }}



  ref - The device that has _CRS containing GpioIo()/GpioInt() resources,

        typically this is the device itself (BTH in our case).

  index - Index of the GpioIo()/GpioInt() resource in _CRS starting from zero.

  pin - Pin in the GpioIo()/GpioInt() resource. Typically this is zero.

  active_low - If 1 the GPIO is marked as active_low.



Since ACPI GpioIo() resource does not have a field saying whether it is

active low or high, the "active_low" argument can be used here.  Setting

it to 1 marks the GPIO as active low.



In our Bluetooth example the "reset-gpio" refers to the second GpioIo()

resource, second pin in that resource with the GPIO number of 31.

drivers/gpio/gpiolib-acpi.c

+64 −14
Original line number Diff line number Diff line
@@ -290,6 +290,7 @@ void acpi_gpiochip_free_interrupts(struct gpio_chip *chip) 
struct acpi_gpio_lookup {

	struct acpi_gpio_info info;

	int index;

	int pin_index;

	struct gpio_desc *desc;

	int n;

};
@@ -303,11 +304,22 @@ static int acpi_find_gpio(struct acpi_resource *ares, void *data) 


	if (lookup->n++ == lookup->index && !lookup->desc) {

		const struct acpi_resource_gpio *agpio = &ares->data.gpio;

		int pin_index = lookup->pin_index;



		if (pin_index >= agpio->pin_table_length)

			return 1;



		lookup->desc = acpi_get_gpiod(agpio->resource_source.string_ptr,

					      agpio->pin_table[0]);

					      agpio->pin_table[pin_index]);

		lookup->info.gpioint =

			agpio->connection_type == ACPI_RESOURCE_GPIO_TYPE_INT;



		/*

		 * ActiveLow is only specified for GpioInt resource. If

		 * GpioIo is used then the only way to set the flag is

		 * to use _DSD "gpios" property.

		 */

		if (lookup->info.gpioint)

			lookup->info.active_low =

				agpio->polarity == ACPI_ACTIVE_LOW;

	}
@@ -317,40 +329,75 @@ static int acpi_find_gpio(struct acpi_resource *ares, void *data) 


/**

 * acpi_get_gpiod_by_index() - get a GPIO descriptor from device resources

 * @dev: pointer to a device to get GPIO from

 * @adev: pointer to a ACPI device to get GPIO from

 * @propname: Property name of the GPIO (optional)

 * @index: index of GpioIo/GpioInt resource (starting from %0)

 * @info: info pointer to fill in (optional)

 *

 * Function goes through ACPI resources for @dev and based on @index looks

 * Function goes through ACPI resources for @adev and based on @index looks

 * up a GpioIo/GpioInt resource, translates it to the Linux GPIO descriptor,

 * and returns it. @index matches GpioIo/GpioInt resources only so if there

 * are total %3 GPIO resources, the index goes from %0 to %2.

 *

 * If @propname is specified the GPIO is looked using device property. In

 * that case @index is used to select the GPIO entry in the property value

 * (in case of multiple).

 *

 * If the GPIO cannot be translated or there is an error an ERR_PTR is

 * returned.

 *

 * Note: if the GPIO resource has multiple entries in the pin list, this

 * function only returns the first.

 */

struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index,

struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev,

					  const char *propname, int index,

					  struct acpi_gpio_info *info)

{

	struct acpi_gpio_lookup lookup;

	struct list_head resource_list;

	struct acpi_device *adev;

	acpi_handle handle;

	bool active_low = false;

	int ret;



	if (!dev)

		return ERR_PTR(-EINVAL);



	handle = ACPI_HANDLE(dev);

	if (!handle || acpi_bus_get_device(handle, &adev))

	if (!adev)

		return ERR_PTR(-ENODEV);



	memset(&lookup, 0, sizeof(lookup));

	lookup.index = index;



	if (propname) {

		struct acpi_reference_args args;



		dev_dbg(&adev->dev, "GPIO: looking up %s\n", propname);



		memset(&args, 0, sizeof(args));

		ret = acpi_dev_get_property_reference(adev, propname, NULL,

						      index, &args);

		if (ret)

			return ERR_PTR(ret);



		/*

		 * The property was found and resolved so need to

		 * lookup the GPIO based on returned args instead.

		 */

		adev = args.adev;

		if (args.nargs >= 2) {

			lookup.index = args.args[0];

			lookup.pin_index = args.args[1];

			/*

			 * 3rd argument, if present is used to

			 * specify active_low.

			 */

			if (args.nargs >= 3)

				active_low = !!args.args[2];

		}



		dev_dbg(&adev->dev, "GPIO: _DSD returned %s %zd %llu %llu %llu\n",

			dev_name(&adev->dev), args.nargs,

			args.args[0], args.args[1], args.args[2]);

	} else {

		dev_dbg(&adev->dev, "GPIO: looking up %d in _CRS\n", index);

	}



	INIT_LIST_HEAD(&resource_list);

	ret = acpi_dev_get_resources(adev, &resource_list, acpi_find_gpio,

				     &lookup);
@@ -359,8 +406,11 @@ struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index, 


	acpi_dev_free_resource_list(&resource_list);



	if (lookup.desc && info)

	if (lookup.desc && info) {

		*info = lookup.info;

		if (active_low)

			info->active_low = active_low;

	}



	return lookup.desc ? lookup.desc : ERR_PTR(-ENOENT);

}

drivers/gpio/gpiolib.c

+26 −4
Original line number Diff line number Diff line
@@ -1505,14 +1505,36 @@ static struct gpio_desc *acpi_find_gpio(struct device *dev, const char *con_id, 
					unsigned int idx,

					enum gpio_lookup_flags *flags)

{

	static const char * const suffixes[] = { "gpios", "gpio" };

	struct acpi_device *adev = ACPI_COMPANION(dev);

	struct acpi_gpio_info info;

	struct gpio_desc *desc;

	char propname[32];

	int i;



	desc = acpi_get_gpiod_by_index(dev, idx, &info);

	/* Try first from _DSD */

	for (i = 0; i < ARRAY_SIZE(suffixes); i++) {

		if (con_id && strcmp(con_id, "gpios")) {

			snprintf(propname, sizeof(propname), "%s-%s",

				 con_id, suffixes[i]);

		} else {

			snprintf(propname, sizeof(propname), "%s",

				 suffixes[i]);

		}



		desc = acpi_get_gpiod_by_index(adev, propname, idx, &info);

		if (!IS_ERR(desc) || (PTR_ERR(desc) == -EPROBE_DEFER))

			break;

	}



	/* Then from plain _CRS GPIOs */

	if (IS_ERR(desc)) {

		desc = acpi_get_gpiod_by_index(adev, NULL, idx, &info);

		if (IS_ERR(desc))

			return desc;

	}



	if (info.gpioint && info.active_low)

	if (info.active_low)

		*flags |= GPIO_ACTIVE_LOW;



	return desc;

drivers/gpio/gpiolib.h

+4 −3
Original line number Diff line number Diff line
@@ -34,7 +34,8 @@ void acpi_gpiochip_remove(struct gpio_chip *chip); 
void acpi_gpiochip_request_interrupts(struct gpio_chip *chip);

void acpi_gpiochip_free_interrupts(struct gpio_chip *chip);



struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index,

struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev,

					  const char *propname, int index,

					  struct acpi_gpio_info *info);

#else

static inline void acpi_gpiochip_add(struct gpio_chip *chip) { }
@@ -47,8 +48,8 @@ static inline void 
acpi_gpiochip_free_interrupts(struct gpio_chip *chip) { }



static inline struct gpio_desc *

acpi_get_gpiod_by_index(struct device *dev, int index,

			struct acpi_gpio_info *info)

acpi_get_gpiod_by_index(struct acpi_device *adev, const char *propname,

			int index, struct acpi_gpio_info *info)

{

	return ERR_PTR(-ENOSYS);

}