gpio / ACPI: Add support for ACPI GPIO operation regions
GPIO operation regions is a new feature introduced in ACPI 5.0 specification. This feature adds a way for platform ASL code to call back to OS GPIO driver and toggle GPIO pins. An example ASL code from Lenovo Miix 2 tablet with only relevant part listed: Device (\_SB.GPO0) { Name (AVBL, Zero) Method (_REG, 2, NotSerialized) { If (LEqual (Arg0, 0x08)) { // Marks the region available Store (Arg1, AVBL) } } OperationRegion (GPOP, GeneralPurposeIo, Zero, 0x0C) Field (GPOP, ByteAcc, NoLock, Preserve) { Connection ( GpioIo (Exclusive, PullDefault, 0, 0, IoRestrictionOutputOnly, "\\_SB.GPO0", 0x00, ResourceConsumer,,) { 0x003B } ), SHD3, 1, } } Device (SHUB) { Method (_PS0, 0, Serialized) { If (LEqual (\_SB.GPO0.AVBL, One)) { Store (One, \_SB.GPO0.SHD3) Sleep (0x32) } } Method (_PS3, 0, Serialized) { If (LEqual (\_SB.GPO0.AVBL, One)) { Store (Zero, \_SB.GPO0.SHD3) } } } How this works is that whenever _PS0 or _PS3 method is run (typically when SHUB device is transitioned to D0 or D3 respectively), ASL code checks if the GPIO operation region is available (\_SB.GPO0.AVBL). If it is we go and store either 0 or 1 to \_SB.GPO0.SHD3. Now, when ACPICA notices ACPI GPIO operation region access (the store above) it will call acpi_gpio_adr_space_handler() that then toggles the GPIO accordingly using standard gpiolib interfaces. Implement the support by registering GPIO operation region handlers for all GPIO devices that have an ACPI handle. First time the GPIO is used by the ASL code we make sure that the GPIO stays requested until the GPIO chip driver itself is unloaded. If we find out that the GPIO is already requested we just toggle it according to the value got from ASL code. Signed-off-by:Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by:
Linus Walleij <linus.walleij@linaro.org>
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a176973e
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