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-rw-r--r--Documentation/gpio/consumer.txt6
-rw-r--r--drivers/gpio/gpiolib.c34
2 files changed, 22 insertions, 18 deletions
diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt
index 07c74a3765a0..e42f77d8d4ca 100644
--- a/Documentation/gpio/consumer.txt
+++ b/Documentation/gpio/consumer.txt
@@ -38,7 +38,11 @@ device that displays digits), an additional index argument can be specified:
const char *con_id, unsigned int idx)
Both functions return either a valid GPIO descriptor, or an error code checkable
-with IS_ERR(). They will never return a NULL pointer.
+with IS_ERR() (they will never return a NULL pointer). -ENOENT will be returned
+if and only if no GPIO has been assigned to the device/function/index triplet,
+other error codes are used for cases where a GPIO has been assigned but an error
+occured while trying to acquire it. This is useful to discriminate between mere
+errors and an absence of GPIO for optional GPIO parameters.
Device-managed variants of these functions are also defined:
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 12e47dfabd8d..c0b06a9adad9 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2367,7 +2367,7 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
unsigned int idx,
enum gpio_lookup_flags *flags)
{
- struct gpio_desc *desc = ERR_PTR(-ENODEV);
+ struct gpio_desc *desc = ERR_PTR(-ENOENT);
struct gpiod_lookup_table *table;
struct gpiod_lookup *p;
@@ -2389,19 +2389,22 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
chip = find_chip_by_name(p->chip_label);
if (!chip) {
- dev_warn(dev, "cannot find GPIO chip %s\n",
- p->chip_label);
- continue;
+ dev_err(dev, "cannot find GPIO chip %s\n",
+ p->chip_label);
+ return ERR_PTR(-ENODEV);
}
if (chip->ngpio <= p->chip_hwnum) {
- dev_warn(dev, "GPIO chip %s has %d GPIOs\n",
- chip->label, chip->ngpio);
- continue;
+ dev_err(dev,
+ "requested GPIO %d is out of range [0..%d] for chip %s\n",
+ idx, chip->ngpio, chip->label);
+ return ERR_PTR(-EINVAL);
}
desc = gpiochip_offset_to_desc(chip, p->chip_hwnum);
*flags = p->flags;
+
+ return desc;
}
return desc;
@@ -2413,7 +2416,8 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
* @con_id: function within the GPIO consumer
*
* Return the GPIO descriptor corresponding to the function con_id of device
- * dev, or an IS_ERR() condition if an error occured.
+ * dev, -ENOENT if no GPIO has been assigned to the requested function, or
+ * another IS_ERR() code if an error occured while trying to acquire the GPIO.
*/
struct gpio_desc *__must_check gpiod_get(struct device *dev, const char *con_id)
{
@@ -2430,7 +2434,9 @@ EXPORT_SYMBOL_GPL(gpiod_get);
* This variant of gpiod_get() allows to access GPIOs other than the first
* defined one for functions that define several GPIOs.
*
- * Return a valid GPIO descriptor, or an IS_ERR() condition in case of error.
+ * Return a valid GPIO descriptor, -ENOENT if no GPIO has been assigned to the
+ * requested function and/or index, or another IS_ERR() code if an error
+ * occured while trying to acquire the GPIO.
*/
struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
const char *con_id,
@@ -2455,15 +2461,9 @@ struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
* Either we are not using DT or ACPI, or their lookup did not return
* a result. In that case, use platform lookup as a fallback.
*/
- if (!desc || IS_ERR(desc)) {
- struct gpio_desc *pdesc;
-
+ if (!desc || desc == ERR_PTR(-ENOENT)) {
dev_dbg(dev, "using lookup tables for GPIO lookup");
- pdesc = gpiod_find(dev, con_id, idx, &flags);
-
- /* If used as fallback, do not replace the previous error */
- if (!IS_ERR(pdesc) || !desc)
- desc = pdesc;
+ desc = gpiod_find(dev, con_id, idx, &flags);
}
if (IS_ERR(desc)) {