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: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/Documentation/acpi/gpio-properties.txt b/Documentation/acpi/gpio-properties.txt
index 09cff657b82cb2fa40f1aacd79646797baae6d93..d9076af271f5d05fa8864d50c31e37756cafcb27 100644 (file)
--- a/Documentation/acpi/gpio-properties.txt
+++ b/Documentation/acpi/gpio-properties.txt
@@ -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
 --------------------------------------
 

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 700ea6ad609b5b824ed4dbdd2d1ecb9f79023d68..4f46982ce982fabfb63727f10878f928a60bd9bb 100644 (file)
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -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)
 {
        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_scan_gpios(acpi_gpio);
        acpi_walk_dep_device_list(handle);
 }