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Commit c80f1ba7 authored by Mika Westerberg's avatar Mika Westerberg Committed by Linus Walleij
Browse files

ACPI / gpio: Add hogging support 



GPIO hogging means that the GPIO controller can "hog" and configure certain
GPIOs without need for a driver or userspace to do that. This is useful in
open-connected boards where BIOS cannot possibly know beforehand which
devices will be connected to the board.

This adds GPIO hogging mechanism to ACPI analogous to Device Tree.

Signed-off-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 6f7194a1

Documentation/acpi/gpio-properties.txt

+35 −0
Original line number Original line Diff line number Diff line
@@ -66,6 +66,41 @@ native: 
      }

      }

  }

  }





Other supported properties

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



Following Device Tree compatible device properties are also supported by

_DSD device properties for GPIO controllers:



- gpio-hog

- output-high

- output-low

- input

- line-name



Example:



  Name (_DSD, Package () {

      // _DSD Hierarchical Properties Extension UUID

      ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),

      Package () {

          Package () {"hog-gpio8", "G8PU"}

      }

  })



  Name (G8PU, Package () {

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

      Package () {

          Package () {"gpio-hog", 1},

          Package () {"gpios", Package () {8, 0}},

          Package () {"output-high", 1},

          Package () {"line-name", "gpio8-pullup"},

      }

  })



See Documentation/devicetree/bindings/gpio/gpio.txt for more information

about these properties.



ACPI GPIO Mappings Provided by Drivers

ACPI GPIO Mappings Provided by Drivers

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

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

drivers/gpio/gpiolib-acpi.c

+71 −0
Original line number Original line Diff line number Diff line
@@ -857,6 +857,76 @@ static void acpi_gpiochip_free_regions(struct acpi_gpio_chip *achip) 
	}

	}

}

}





struct gpio_desc *acpi_gpiochip_parse_own_gpio(struct acpi_gpio_chip *achip,

	struct fwnode_handle *fwnode, const char **name, unsigned int *lflags,

	unsigned int *dflags)

{

	struct gpio_chip *chip = achip->chip;

	struct gpio_desc *desc;

	u32 gpios[2];

	int ret;



	ret = fwnode_property_read_u32_array(fwnode, "gpios", gpios,

					     ARRAY_SIZE(gpios));

	if (ret < 0)

		return ERR_PTR(ret);



	ret = acpi_gpiochip_pin_to_gpio_offset(chip->gpiodev, gpios[0]);

	if (ret < 0)

		return ERR_PTR(ret);



	desc = gpiochip_get_desc(chip, ret);

	if (IS_ERR(desc))

		return desc;



	*lflags = 0;

	*dflags = 0;

	*name = NULL;



	if (gpios[1])

		*lflags |= GPIO_ACTIVE_LOW;



	if (fwnode_property_present(fwnode, "input"))

		*dflags |= GPIOD_IN;

	else if (fwnode_property_present(fwnode, "output-low"))

		*dflags |= GPIOD_OUT_LOW;

	else if (fwnode_property_present(fwnode, "output-high"))

		*dflags |= GPIOD_OUT_HIGH;

	else

		return ERR_PTR(-EINVAL);



	fwnode_property_read_string(fwnode, "line-name", name);



	return desc;

}



static void acpi_gpiochip_scan_gpios(struct acpi_gpio_chip *achip)

{

	struct gpio_chip *chip = achip->chip;

	struct fwnode_handle *fwnode;



	device_for_each_child_node(chip->parent, fwnode) {

		unsigned int lflags, dflags;

		struct gpio_desc *desc;

		const char *name;

		int ret;



		if (!fwnode_property_present(fwnode, "gpio-hog"))

			continue;



		desc = acpi_gpiochip_parse_own_gpio(achip, fwnode, &name,

						    &lflags, &dflags);

		if (IS_ERR(desc))

			continue;



		ret = gpiod_hog(desc, name, lflags, dflags);

		if (ret) {

			dev_err(chip->parent, "Failed to hog GPIO\n");

			return;

		}

	}

}



void acpi_gpiochip_add(struct gpio_chip *chip)

void acpi_gpiochip_add(struct gpio_chip *chip)

{

{

	struct acpi_gpio_chip *acpi_gpio;

	struct acpi_gpio_chip *acpi_gpio;
@@ -888,6 +958,7 @@ void acpi_gpiochip_add(struct gpio_chip *chip) 
	}

	}





	acpi_gpiochip_request_regions(acpi_gpio);

	acpi_gpiochip_request_regions(acpi_gpio);

	acpi_gpiochip_scan_gpios(acpi_gpio);

	acpi_walk_dep_device_list(handle);

	acpi_walk_dep_device_list(handle);

}

}