gpiolib: add gpiod_get() and gpiod_put() functions

Add gpiod_get(), gpiod_get_index() and gpiod_put() functions that
provide safer management of GPIOs.

These functions put the GPIO framework in line with the conventions of
other frameworks in the kernel, and help ensure every GPIO is declared
properly and valid while it is used.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 56 insertions, 0 deletions

diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 5dc172c72f0f..cd9da3885d79 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -124,4 +124,60 @@ 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);
 
+/**
+ * Lookup table for associating GPIOs to specific devices and functions using
+ * platform data.
+ */
+struct gpiod_lookup {
+        struct list_head list;
+        /*
+         * name of the chip the GPIO belongs to
+         */
+        const char *chip_label;
+        /*
+         * hardware number (i.e. relative to the chip) of the GPIO
+         */
+        u16 chip_hwnum;
+        /*
+         * name of device that can claim this GPIO
+         */
+        const char *dev_id;
+        /*
+         * name of the GPIO from the device's point of view
+         */
+        const char *con_id;
+        /*
+         * index of the GPIO in case several GPIOs share the same name
+         */
+        unsigned int idx;
+        /*
+         * mask of GPIOF_* values
+         */
+        unsigned long flags;
+};
+
+/*
+ * Simple definition of a single GPIO under a con_id
+ */
+#define GPIO_LOOKUP(_chip_label, _chip_hwnum, _dev_id, _con_id, _flags) \
+        GPIO_LOOKUP_IDX(_chip_label, _chip_hwnum, _dev_id, _con_id, 0, _flags)
+
+/*
+ * Use this macro if you need to have several GPIOs under the same con_id.
+ * Each GPIO needs to use a different index and can be accessed using
+ * gpiod_get_index()
+ */
+#define GPIO_LOOKUP_IDX(_chip_label, _chip_hwnum, _dev_id, _con_id, _idx, \
+                        _flags)                                           \
+{                                                                         \
+        .chip_label = _chip_label,                                        \
+        .chip_hwnum = _chip_hwnum,                                        \
+        .dev_id = _dev_id,                                                \
+        .con_id = _con_id,                                                \
+        .idx = _idx,                                                      \
+        .flags = _flags,                                                  \
+}
+
+void gpiod_add_table(struct gpiod_lookup *table, size_t size);
+
 #endif