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authorMika Westerberg <mika.westerberg@linux.intel.com>2014-10-29 15:41:01 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-11-04 21:58:22 +0100
commit0d9a693cc8619b28f0eeb689a554647d42848fde (patch)
treea5df01e1767f6a537531ad5bfc69cb9b2097bdf6 /drivers/gpio/gpiolib-acpi.c
parentf60e7074902a66d9a132a971ecda63ee5b8bc154 (diff)
downloadop-kernel-dev-0d9a693cc8619b28f0eeb689a554647d42848fde.zip
op-kernel-dev-0d9a693cc8619b28f0eeb689a554647d42848fde.tar.gz
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>
Diffstat (limited to 'drivers/gpio/gpiolib-acpi.c')
-rw-r--r--drivers/gpio/gpiolib-acpi.c78
1 files changed, 64 insertions, 14 deletions
diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 05c6275..8aa6ca4 100644
--- 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);
}
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