add ax88772_rst

hc

2024-05-10 9999e48639b3cecb08ffb37358bcba3b48161b29

 kernel/Documentation/driver-api/gpio/board.rst
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@@ -101,7 +101,7 @@
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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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+Documentation/firmware-guide/acpi/gpio-properties.rst.
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 Platform Data
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 -------------
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@@ -113,13 +113,15 @@
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 GPIOs are mapped by the means of tables of lookups, containing instances of the
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 gpiod_lookup structure. Two macros are defined to help declaring such mappings::
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-	GPIO_LOOKUP(chip_label, chip_hwnum, con_id, flags)
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-	GPIO_LOOKUP_IDX(chip_label, chip_hwnum, con_id, idx, flags)
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+	GPIO_LOOKUP(key, chip_hwnum, con_id, flags)
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+	GPIO_LOOKUP_IDX(key, chip_hwnum, con_id, idx, flags)
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 where
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-  - chip_label is the label of the gpiod_chip instance providing the GPIO
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-  - chip_hwnum is the hardware number of the GPIO within the chip
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+  - key is either the label of the gpiod_chip instance providing the GPIO, or
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+    the GPIO line name
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+  - chip_hwnum is the hardware number of the GPIO within the chip, or U16_MAX
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+    to indicate that key is a GPIO line name
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   - con_id is the name of the GPIO function from the device point of view. It
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 	can be NULL, in which case it will match any function.
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   - idx is the index of the GPIO within the function.
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@@ -135,7 +137,10 @@
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 In the future, these flags might be extended to support more properties.
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-Note that GPIO_LOOKUP() is just a shortcut to GPIO_LOOKUP_IDX() where idx = 0.
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+Note that:
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+  1. GPIO line names are not guaranteed to be globally unique, so the first
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+     match found will be used.
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+  2. GPIO_LOOKUP() is just a shortcut to GPIO_LOOKUP_IDX() where idx = 0.
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 A lookup table can then be defined as follows, with an empty entry defining its
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 end. The 'dev_id' field of the table is the identifier of the device that will
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 The line will be hogged as soon as the gpiochip is created or - in case the
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 chip was created earlier - when the hog table is registered.
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+
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+Arrays of pins
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+--------------
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+In addition to requesting pins belonging to a function one by one, a device may
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+also request an array of pins assigned to the function.  The way those pins are
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+mapped to the device determines if the array qualifies for fast bitmap
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+processing.  If yes, a bitmap is passed over get/set array functions directly
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+between a caller and a respective .get/set_multiple() callback of a GPIO chip.
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+
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+In order to qualify for fast bitmap processing, the array must meet the
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+following requirements:
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+
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+- pin hardware number of array member 0 must also be 0,
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+- pin hardware numbers of consecutive array members which belong to the same
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+  chip as member 0 does must also match their array indexes.
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+
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+Otherwise fast bitmap processing path is not used in order to avoid consecutive
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+pins which belong to the same chip but are not in hardware order being processed
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+separately.
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+
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+If the array applies for fast bitmap processing path, pins which belong to
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+different chips than member 0 does, as well as those with indexes different from
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+their hardware pin numbers, are excluded from the fast path, both input and
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+output.  Moreover, open drain and open source pins are excluded from fast bitmap
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+output processing.