gpiolib-acpi: introduce acpi_get_gpio_by_index() helper

[firefly-linux-kernel-4.4.55.git] / drivers / gpio / gpiolib-acpi.c

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 89336c4f82cd34f1257c7bca1109fa332c71eac6..5c1ef2b3ef188253e0031b0ceec2e65239220df5 100644 (file)
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -201,6 +201,83 @@ void acpi_gpiochip_request_interrupts(struct gpio_chip *chip)
 }
 EXPORT_SYMBOL(acpi_gpiochip_request_interrupts);
 
+struct acpi_gpio_lookup {
+       struct acpi_gpio_info info;
+       int index;
+       int gpio;
+       int n;
+};
+
+static int acpi_find_gpio(struct acpi_resource *ares, void *data)
+{
+       struct acpi_gpio_lookup *lookup = data;
+
+       if (ares->type != ACPI_RESOURCE_TYPE_GPIO)
+               return 1;
+
+       if (lookup->n++ == lookup->index && lookup->gpio < 0) {
+               const struct acpi_resource_gpio *agpio = &ares->data.gpio;
+
+               lookup->gpio = acpi_get_gpio(agpio->resource_source.string_ptr,
+                                            agpio->pin_table[0]);
+               lookup->info.gpioint =
+                       agpio->connection_type == ACPI_RESOURCE_GPIO_TYPE_INT;
+       }
+
+       return 1;
+}
+
+/**
+ * acpi_get_gpio_by_index() - get a GPIO number from device resources
+ * @dev: pointer to a device to get GPIO from
+ * @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
+ * up a GpioIo/GpioInt resource, translates it to the Linux GPIO number,
+ * 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 the GPIO cannot be translated or there is an error, negative errno is
+ * returned.
+ *
+ * Note: if the GPIO resource has multiple entries in the pin list, this
+ * function only returns the first.
+ */
+int acpi_get_gpio_by_index(struct device *dev, int index,
+                          struct acpi_gpio_info *info)
+{
+       struct acpi_gpio_lookup lookup;
+       struct list_head resource_list;
+       struct acpi_device *adev;
+       acpi_handle handle;
+       int ret;
+
+       if (!dev)
+               return -EINVAL;
+
+       handle = ACPI_HANDLE(dev);
+       if (!handle || acpi_bus_get_device(handle, &adev))
+               return -ENODEV;
+
+       memset(&lookup, 0, sizeof(lookup));
+       lookup.index = index;
+       lookup.gpio = -ENODEV;
+
+       INIT_LIST_HEAD(&resource_list);
+       ret = acpi_dev_get_resources(adev, &resource_list, acpi_find_gpio,
+                                    &lookup);
+       if (ret < 0)
+               return ret;
+
+       acpi_dev_free_resource_list(&resource_list);
+
+       if (lookup.gpio >= 0 && info)
+               *info = lookup.info;
+
+       return lookup.gpio;
+}
+EXPORT_SYMBOL_GPL(acpi_get_gpio_by_index);
 
 /**
  * acpi_gpiochip_free_interrupts() - Free GPIO _EVT ACPI event interrupts.