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gpio: better lookup method for platform GPIOs

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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>
This commit is contained in:
Alexandre Courbot 2013-12-03 12:20:11 +09:00 • committed by Linus Walleij
parent bdc54ef45d
commit ad824783fb
3 changed files with 87 additions and 74 deletions
Download patch file Download diff file Expand all files Collapse all files

21
include/linux/gpio/driver.h
View file

@ -141,7 +141,6 @@ enum gpio_lookup_flags {
* platform data.
*/
struct gpiod_lookup {
struct list_head list;
/*
* name of the chip the GPIO belongs to
*/
@ -150,10 +149,6 @@ struct gpiod_lookup {
* hardware number (i.e. relative to the chip) of the GPIO
*/
u16 chip_hwnum;
/*
* name of device that can claim this GPIO
*/
const char *dev_id;
/*
* name of the GPIO from the device's point of view
*/
@ -168,28 +163,32 @@ struct gpiod_lookup {
enum gpio_lookup_flags flags;
};
struct gpiod_lookup_table {
struct list_head list;
const char *dev_id;
struct gpiod_lookup table[];
};
/*
* Simple definition of a single GPIO under a con_id
*/
#define GPIO_LOOKUP(_chip_label, _chip_hwnum, _dev_id, _con_id, _flags) \
GPIO_LOOKUP_IDX(_chip_label, _chip_hwnum, _dev_id, _con_id, 0, _flags)
#define GPIO_LOOKUP(_chip_label, _chip_hwnum, _con_id, _flags) \
GPIO_LOOKUP_IDX(_chip_label, _chip_hwnum, _con_id, 0, _flags)
/*
* Use this macro if you need to have several GPIOs under the same con_id.
* Each GPIO needs to use a different index and can be accessed using
* gpiod_get_index()
*/
#define GPIO_LOOKUP_IDX(_chip_label, _chip_hwnum, _dev_id, _con_id, _idx, \
_flags) \
#define GPIO_LOOKUP_IDX(_chip_label, _chip_hwnum, _con_id, _idx, _flags) \
{ \
.chip_label = _chip_label, \
.chip_hwnum = _chip_hwnum, \
.dev_id = _dev_id, \
.con_id = _con_id, \
.idx = _idx, \
.flags = _flags, \
}
void gpiod_add_table(struct gpiod_lookup *table, size_t size);
void gpiod_add_lookup_table(struct gpiod_lookup_table *table);
#endif