gpiolib: add gpiochip_get_desc() driver function

Some drivers dealing with a gpio_chip might need to act on its
descriptors directly; one example is pinctrl drivers that need to lock a
GPIO for being used as IRQ using gpiod_lock_as_irq().

This patch exports a gpiochip_get_desc() function that returns the
GPIO descriptor at the requested index. It also sweeps the
gpio_to_chip() function out of the consumer interface since any holder
of a gpio_chip reference can manipulate its GPIOs way beyond what a
consumer should be allowed to do.

As a result, gpio_chip is not visible anymore to simple GPIO consumers.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 9 insertions, 8 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 9b241bcb510..9cd7082cca0 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -164,16 +164,17 @@ struct gpio_desc *gpio_to_desc(unsigned gpio)
 EXPORT_SYMBOL_GPL(gpio_to_desc);
 
 /**
- * Convert an offset on a certain chip to a corresponding descriptor
+ * Get the GPIO descriptor corresponding to the given hw number for this chip.
  */
-static struct gpio_desc *gpiochip_offset_to_desc(struct gpio_chip *chip,
-						 unsigned int offset)
+struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip,
+				    u16 hwnum)
 {
-	if (offset >= chip->ngpio)
+	if (hwnum >= chip->ngpio)
 		return ERR_PTR(-EINVAL);
 
-	return &chip->desc[offset];
+	return &chip->desc[hwnum];
 }
+EXPORT_SYMBOL_GPL(gpiochip_get_desc);
 
 /**
  * Convert a GPIO descriptor to the integer namespace.
@@ -2190,7 +2191,7 @@ EXPORT_SYMBOL_GPL(gpiod_lock_as_irq);
 
 int gpio_lock_as_irq(struct gpio_chip *chip, unsigned int offset)
 {
-	return gpiod_lock_as_irq(gpiochip_offset_to_desc(chip, offset));
+	return gpiod_lock_as_irq(gpiochip_get_desc(chip, offset));
 }
 EXPORT_SYMBOL_GPL(gpio_lock_as_irq);
 
@@ -2212,7 +2213,7 @@ EXPORT_SYMBOL_GPL(gpiod_unlock_as_irq);
 
 void gpio_unlock_as_irq(struct gpio_chip *chip, unsigned int offset)
 {
-	return gpiod_unlock_as_irq(gpiochip_offset_to_desc(chip, offset));
+	return gpiod_unlock_as_irq(gpiochip_get_desc(chip, offset));
 }
 EXPORT_SYMBOL_GPL(gpio_unlock_as_irq);
 
@@ -2433,7 +2434,7 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
 			return ERR_PTR(-EINVAL);
 		}
 
-		desc = gpiochip_offset_to_desc(chip, p->chip_hwnum);
+		desc = gpiochip_get_desc(chip, p->chip_hwnum);
 		*flags = p->flags;
 
 		return desc;