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>
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 44a2327..4eb262a 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2260,18 +2260,14 @@
EXPORT_SYMBOL_GPL(gpiod_set_value_cansleep);
/**
- * gpiod_add_table() - register GPIO device consumers
- * @table: array of consumers to register
- * @num: number of consumers in table
+ * gpiod_add_lookup_table() - register GPIO device consumers
+ * @table: table of consumers to register
*/
-void gpiod_add_table(struct gpiod_lookup *table, size_t size)
+void gpiod_add_lookup_table(struct gpiod_lookup_table *table)
{
mutex_lock(&gpio_lookup_lock);
- while (size--) {
- list_add_tail(&table->list, &gpio_lookup_list);
- table++;
- }
+ list_add_tail(&table->list, &gpio_lookup_list);
mutex_unlock(&gpio_lookup_lock);
}
@@ -2327,72 +2323,84 @@
return desc;
}
+static struct gpiod_lookup_table *gpiod_find_lookup_table(struct device *dev)
+{
+ const char *dev_id = dev ? dev_name(dev) : NULL;
+ struct gpiod_lookup_table *table;
+
+ mutex_lock(&gpio_lookup_lock);
+
+ list_for_each_entry(table, &gpio_lookup_list, list) {
+ if (table->dev_id && dev_id) {
+ /*
+ * Valid strings on both ends, must be identical to have
+ * a match
+ */
+ if (!strcmp(table->dev_id, dev_id))
+ goto found;
+ } else {
+ /*
+ * One of the pointers is NULL, so both must be to have
+ * a match
+ */
+ if (dev_id == table->dev_id)
+ goto found;
+ }
+ }
+ table = NULL;
+
+found:
+ mutex_unlock(&gpio_lookup_lock);
+ return table;
+}
+
static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
unsigned int idx,
enum gpio_lookup_flags *flags)
{
- const char *dev_id = dev ? dev_name(dev) : NULL;
struct gpio_desc *desc = ERR_PTR(-ENODEV);
- unsigned int match, best = 0;
+ struct gpiod_lookup_table *table;
struct gpiod_lookup *p;
- mutex_lock(&gpio_lookup_lock);
+ table = gpiod_find_lookup_table(dev);
+ if (!table)
+ return desc;
- list_for_each_entry(p, &gpio_lookup_list, list) {
- match = 0;
+ for (p = &table->table[0]; p->chip_label; p++) {
+ struct gpio_chip *chip;
- if (p->dev_id) {
- if (!dev_id || strcmp(p->dev_id, dev_id))
- continue;
-
- match += 2;
- }
-
- if (p->con_id) {
- if (!con_id || strcmp(p->con_id, con_id))
- continue;
-
- match += 1;
- }
-
+ /* idx must always match exactly */
if (p->idx != idx)
continue;
- if (match > best) {
- struct gpio_chip *chip;
+ /* If the lookup entry has a con_id, require exact match */
+ if (p->con_id && (!con_id || strcmp(p->con_id, con_id)))
+ continue;
- chip = find_chip_by_name(p->chip_label);
+ chip = find_chip_by_name(p->chip_label);
- if (!chip) {
- dev_warn(dev, "cannot find GPIO chip %s\n",
- p->chip_label);
- continue;
- }
-
- if (chip->ngpio <= p->chip_hwnum) {
- dev_warn(dev, "GPIO chip %s has %d GPIOs\n",
- chip->label, chip->ngpio);
- continue;
- }
-
- desc = gpio_to_desc(chip->base + p->chip_hwnum);
- *flags = p->flags;
-
- if (match != 3)
- best = match;
- else
- break;
+ if (!chip) {
+ dev_warn(dev, "cannot find GPIO chip %s\n",
+ p->chip_label);
+ continue;
}
- }
- mutex_unlock(&gpio_lookup_lock);
+ if (chip->ngpio <= p->chip_hwnum) {
+ dev_warn(dev, "GPIO chip %s has %d GPIOs\n",
+ chip->label, chip->ngpio);
+ continue;
+ }
+
+ desc = gpiochip_offset_to_desc(chip, p->chip_hwnum);
+ *flags = p->flags;
+ }
return desc;
}
/**
* gpio_get - obtain a GPIO for a given GPIO function
- * @dev: GPIO consumer
+ * @dev: GPIO consumer, can be NULL for system-global GPIOs
* @con_id: function within the GPIO consumer
*
* Return the GPIO descriptor corresponding to the function con_id of device
