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Subject[PATCH 1/2] gpiolib: add gpiochip_get_desc() driver function
Date
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>
---
Jean-Jacques, I think you will want to use this function for locking GPIOs
in the AT91 pinctrl driver. Mika, we talked about this a while ago already,
but here it is finally. Next patch uses it in the GPIO ACPI driver.

drivers/gpio/gpiolib.c | 17 +++++++++--------
include/linux/gpio/consumer.h | 8 --------
include/linux/gpio/driver.h | 18 ++++++++++++++++++
3 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 50c4922..f60d74b 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.
@@ -2161,7 +2162,7 @@ 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);

@@ -2183,7 +2184,7 @@ 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);

@@ -2404,7 +2405,7 @@ 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;
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index 7a8144f..f6a9cc3 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -5,7 +5,6 @@
#include <linux/kernel.h>

struct device;
-struct gpio_chip;

/**
* Opaque descriptor for a GPIO. These are obtained using gpiod_get() and are
@@ -59,7 +58,6 @@ 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 */

@@ -207,12 +205,6 @@ 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 a3e181e..9fe2836 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
--
1.8.5.4


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