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>

1 files changed, 10 insertions, 11 deletions

diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index c849676c6787..44c66b29a2d9 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -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
          */
@@ -151,10 +150,6 @@ struct gpiod_lookup {
          */
         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
          */
         const char *con_id;
@@ -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