[PATCH v2 1/5] gpio: add support to get local gpio number

[Marco Felsch <m.felsch@pengutronix.de>]

Sometimes consumers needs to know the gpio-chip local gpio number of a
'struct gpio_desc' for further configuration. This is often the case for
mfd devices.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
 drivers/gpio/gpiolib.c        |  6 ++++++
 include/linux/gpio/consumer.h | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 104ed299d5ea..7709648313fc 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -4377,6 +4377,12 @@ int gpiod_count(struct device *dev, const char *con_id)
 }
 EXPORT_SYMBOL_GPL(gpiod_count);
 
+int gpiod_to_offset(struct gpio_desc *desc)
+{
+	return gpio_chip_hwgpio(desc);
+}
+EXPORT_SYMBOL_GPL(gpiod_to_offset);
+
 /**
  * gpiod_get - obtain a GPIO for a given GPIO function
  * @dev:	GPIO consumer, can be NULL for system-global GPIOs
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index b70af921c614..e2178c3bf7fd 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -60,6 +60,9 @@ enum gpiod_flags {
 /* Return the number of GPIOs associated with a device / function */
 int gpiod_count(struct device *dev, const char *con_id);
 
+/* Get the local chip offset from a global desc */
+int gpiod_to_offset(struct gpio_desc *desc);
+
 /* Acquire and dispose GPIOs */
 struct gpio_desc *__must_check gpiod_get(struct device *dev,
 					 const char *con_id,
@@ -189,6 +192,13 @@ static inline int gpiod_count(struct device *dev, const char *con_id)
 	return 0;
 }
 
+static inline int gpiod_to_offset(struct gpio_desc *desc)
+{
+	/* GPIO can never have been requested */
+	WARN_ON(desc);
+	return 0;
+}
+
 static inline struct gpio_desc *__must_check gpiod_get(struct device *dev,
 						       const char *con_id,
 						       enum gpiod_flags flags)
-- 
2.20.1