forked from luck/tmp_suning_uos_patched
Documentation: gpio: Update ACPI part of the document to mention _DSD
With ACPI 5.1 _DSD (Device Specific Data) it is now possible to name functions just like Device Tree is doing. Make sure that the documentation mentions _DSD as the recommended way to describe GPIOs in ACPI systems. Reported-by: Darren Hart <dvhart@linux.intel.com> Reviewed-by: Darren Hart <dvhart@linux.intel.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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@ -50,10 +50,43 @@ gpiod_is_active_low(power) will be true).
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ACPI
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----
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ACPI does not support function names for GPIOs. Therefore, only the "idx"
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argument of gpiod_get_index() is useful to discriminate between GPIOs assigned
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to a device. The "con_id" argument can still be set for debugging purposes (it
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will appear under error messages as well as debug and sysfs nodes).
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ACPI also supports function names for GPIOs in a similar fashion to DT.
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The above DT example can be converted to an equivalent ACPI description
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with the help of _DSD (Device Specific Data), introduced in ACPI 5.1:
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Device (FOO) {
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Name (_CRS, ResourceTemplate () {
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GpioIo (Exclusive, ..., IoRestrictionOutputOnly,
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"\\_SB.GPI0") {15} // red
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GpioIo (Exclusive, ..., IoRestrictionOutputOnly,
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"\\_SB.GPI0") {16} // green
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GpioIo (Exclusive, ..., IoRestrictionOutputOnly,
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"\\_SB.GPI0") {17} // blue
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GpioIo (Exclusive, ..., IoRestrictionOutputOnly,
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"\\_SB.GPI0") {1} // power
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})
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Name (_DSD, Package () {
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ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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Package () {
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Package () {
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"led-gpios",
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Package () {
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^FOO, 0, 0, 1,
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^FOO, 1, 0, 1,
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^FOO, 2, 0, 1,
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}
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},
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Package () {
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"power-gpios",
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Package () {^FOO, 3, 0, 0},
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},
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}
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})
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}
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For more information about the ACPI GPIO bindings see
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Documentation/acpi/gpio-properties.txt.
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Platform Data
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-------------
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