gpiolib-acpi: introduce acpi_get_gpio_by_index() helper

[firefly-linux-kernel-4.4.55.git] / Documentation / acpi / enumeration.txt

diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt
index 94a656131885f9bd7a2761c9a9b0e6853db54789..b0d541042ac61c7d5cf580d4fc37a486ea96521e 100644 (file)
--- a/Documentation/acpi/enumeration.txt
+++ b/Documentation/acpi/enumeration.txt
@@ -199,6 +199,8 @@ the device to the driver. For example:
        {
                Name (SBUF, ResourceTemplate()
                {
+                       ...
+                       // Used to power on/off the device
                        GpioIo (Exclusive, PullDefault, 0x0000, 0x0000,
                                IoRestrictionOutputOnly, "\\_SB.PCI0.GPI0",
                                0x00, ResourceConsumer,,)
@@ -206,10 +208,20 @@ the device to the driver. For example:
                                // Pin List
                                0x0055
                        }
+
+                       // Interrupt for the device
+                       GpioInt (Edge, ActiveHigh, ExclusiveAndWake, PullNone,
+                                0x0000, "\\_SB.PCI0.GPI0", 0x00, ResourceConsumer,,)
+                       {
+                               // Pin list
+                               0x0058
+                       }
+
                        ...
 
-                       Return (SBUF)
                }
+
+               Return (SBUF)
        }
 
 These GPIO numbers are controller relative and path "\\_SB.PCI0.GPI0"
@@ -220,6 +232,24 @@ The driver can do this by including <linux/acpi_gpio.h> and then calling
 acpi_get_gpio(path, gpio). This will return the Linux GPIO number or
 negative errno if there was no translation found.
 
+In a simple case of just getting the Linux GPIO number from device
+resources one can use acpi_get_gpio_by_index() helper function. It takes
+pointer to the device and index of the GpioIo/GpioInt descriptor in the
+device resources list. For example:
+
+       int gpio_irq, gpio_power;
+       int ret;
+
+       gpio_irq = acpi_get_gpio_by_index(dev, 1, NULL);
+       if (gpio_irq < 0)
+               /* handle error */
+
+       gpio_power = acpi_get_gpio_by_index(dev, 0, NULL);
+       if (gpio_power < 0)
+               /* handle error */
+
+       /* Now we can use the GPIO numbers */
+
 Other GpioIo parameters must be converted first by the driver to be
 suitable to the gpiolib before passing them.