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/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index e8e98ca..2bca049 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1505,14 +1505,36 @@
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]);
+ }
- if (info.gpioint && info.active_low)
+ 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.active_low)
*flags |= GPIO_ACTIVE_LOW;
return desc;