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

diff --git a/Documentation/acpi/gpio-properties.txt b/Documentation/acpi/gpio-properties.txt
new file mode 100644 (file)
index 0000000..3e45b8b
--- /dev/null
+++ b/Documentation/acpi/gpio-properties.txt
@@ -0,0 +1,52 @@
+_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.

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 05c6275..8aa6ca4 100644 (file)
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -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;
 };
@@ -303,13 +304,24 @@ 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;
-               lookup->info.active_low =
-                       agpio->polarity == ACPI_ACTIVE_LOW;
+
+               /*
+                * 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;
        }
 
        return 1;
@@ -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);
 }

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index e8e98ca..2bca049 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -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);
-       if (IS_ERR(desc))
-               return desc;
+       /* 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;

diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 9db2b6a..e3a5211 100644 (file)
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -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);
 }