Eric Lee / smarc-fsl-linux-kernel

04 May, 2015

1 commit

05 Nov, 2014

2 commits

  • e36d453e9   ACPI / GPIO: Document ACPI GPIO mappings API ... Browse Code »

    Document the previously introduced method that can be used by device
    drivers to provide the GPIO subsystem with mappings between GPIO names
    (connection IDs) and GpioIo()/GpioInt() resources in _CRS.

    Signed-off-by: Rafael J. Wysocki
    Reviewed-by: Mika Westerberg

    Rafael J. Wysocki
     
  • 0d9a693cc   gpio / ACPI: Add support for _DSD device properties ... Browse Code »

    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
    Acked-by: Linus Walleij
    Acked-by: Grant Likely
    Signed-off-by: Rafael J. Wysocki

    Mika Westerberg