diff options
| author | Alexandre Courbot <acourbot@nvidia.com> | 2013-12-03 12:20:11 +0900 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2013-12-09 14:05:51 +0100 |
| commit | ad824783fb23bbc8295cffb6214b3b82d25f7d4a (patch) | |
| tree | 745d128c1d04dca7a6c7b10dd737f116f13ddcb1 /Documentation/gpio | |
| parent | bdc54ef45d7670aeb52ce73f8b7ad5f3e5563661 (diff) | |
gpio: better lookup method for platform GPIOs
Change the format of the platform GPIO lookup tables to make them less
confusing and improve lookup efficiency.
The previous format was a single linked-list that required to compare
the device name and function ID of every single GPIO defined for each
lookup. Switch that to a list of per-device tables, so that the lookup
can be done in two steps, omitting the GPIOs that are not relevant for a
particular device.
The matching rules are now defined as follows:
- The device name must match *exactly*, and can be NULL for GPIOs not
assigned to a particular device,
- If the function ID in the lookup table is NULL, the con_id argument of
gpiod_get() will not be used for lookup. However, if it is defined, it
must match exactly.
- The index must always match.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'Documentation/gpio')
| -rw-r--r-- | Documentation/gpio/board.txt | 28 |
1 files changed, 17 insertions, 11 deletions
diff --git a/Documentation/gpio/board.txt b/Documentation/gpio/board.txt index 0d03506f2cc5..ba169faad5c6 100644 --- a/Documentation/gpio/board.txt +++ b/Documentation/gpio/board.txt @@ -72,10 +72,11 @@ where - chip_label is the label of the gpiod_chip instance providing the GPIO - chip_hwnum is the hardware number of the GPIO within the chip - - dev_id is the identifier of the device that will make use of this GPIO. If - NULL, the GPIO will be available to all devices. + - dev_id is the identifier of the device that will make use of this GPIO. It + can be NULL, in which case it will be matched for calls to gpiod_get() + with a NULL device. - con_id is the name of the GPIO function from the device point of view. It - can be NULL. + can be NULL, in which case it will match any function. - idx is the index of the GPIO within the function. - flags is defined to specify the following properties: * GPIOF_ACTIVE_LOW - to configure the GPIO as active-low @@ -86,18 +87,23 @@ In the future, these flags might be extended to support more properties. Note that GPIO_LOOKUP() is just a shortcut to GPIO_LOOKUP_IDX() where idx = 0. -A lookup table can then be defined as follows: +A lookup table can then be defined as follows, with an empty entry defining its +end: - struct gpiod_lookup gpios_table[] = { - GPIO_LOOKUP_IDX("gpio.0", 15, "foo.0", "led", 0, GPIO_ACTIVE_HIGH), - GPIO_LOOKUP_IDX("gpio.0", 16, "foo.0", "led", 1, GPIO_ACTIVE_HIGH), - GPIO_LOOKUP_IDX("gpio.0", 17, "foo.0", "led", 2, GPIO_ACTIVE_HIGH), - GPIO_LOOKUP("gpio.0", 1, "foo.0", "power", GPIO_ACTIVE_LOW), - }; +struct gpiod_lookup_table gpios_table = { + .dev_id = "foo.0", + .table = { + GPIO_LOOKUP_IDX("gpio.0", 15, "led", 0, GPIO_ACTIVE_HIGH), + GPIO_LOOKUP_IDX("gpio.0", 16, "led", 1, GPIO_ACTIVE_HIGH), + GPIO_LOOKUP_IDX("gpio.0", 17, "led", 2, GPIO_ACTIVE_HIGH), + GPIO_LOOKUP("gpio.0", 1, "power", GPIO_ACTIVE_LOW), + { }, + }, +}; And the table can be added by the board code as follows: - gpiod_add_table(gpios_table, ARRAY_SIZE(gpios_table)); + gpiod_add_lookup_table(&gpios_table); The driver controlling "foo.0" will then be able to obtain its GPIOs as follows: |