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>

2 files changed, 18 insertions, 8 deletions

diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index 387994325122..dccda505ba7c 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -7,7 +7,6 @@
 #ifdef CONFIG_GPIOLIB
 
 struct device;
-struct gpio_chip;
 
 /**
  * Opaque descriptor for a GPIO. These are obtained using gpiod_get() and are
@@ -60,7 +59,6 @@ int gpiod_to_irq(const struct gpio_desc *desc);
 /* Convert between the old gpio_ and new gpiod_ interfaces */
 struct gpio_desc *gpio_to_desc(unsigned gpio);
 int desc_to_gpio(const struct gpio_desc *desc);
-struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc);
 
 #else /* CONFIG_GPIOLIB */
 
@@ -214,12 +212,6 @@ static inline int desc_to_gpio(const struct gpio_desc *desc)
         WARN_ON(1);
         return -EINVAL;
 }
-static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
-{
-        /* GPIO can never have been requested */
-        WARN_ON(1);
-        return ERR_PTR(-ENODEV);
-}
 
 
 #endif /* CONFIG_GPIOLIB */
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index a3e181e09636..9fe283642253 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -10,6 +10,8 @@ struct of_phandle_args;
 struct device_node;
 struct seq_file;
 
+#ifdef CONFIG_GPIOLIB
+
 /**
  * struct gpio_chip - abstract a GPIO controller
  * @label: for diagnostics
@@ -129,6 +131,11 @@ extern struct gpio_chip *gpiochip_find(void *data,
 int gpiod_lock_as_irq(struct gpio_desc *desc);
 void gpiod_unlock_as_irq(struct gpio_desc *desc);
 
+struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc);
+
+struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip,
+                                    u16 hwnum);
+
 enum gpio_lookup_flags {
         GPIO_ACTIVE_HIGH = (0 << 0),
         GPIO_ACTIVE_LOW = (1 << 0),
@@ -183,4 +190,15 @@ struct gpiod_lookup_table {
 
 void gpiod_add_lookup_table(struct gpiod_lookup_table *table);
 
+#else /* CONFIG_GPIOLIB */
+
+static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
+{
+        /* GPIO can never have been requested */
+        WARN_ON(1);
+        return ERR_PTR(-ENODEV);
+}
+
+#endif /* CONFIG_GPIOLIB */
+
 #endif