gpiolib: export descriptor-based GPIO interface

This patch exports the gpiod_* family of API functions, a safer
alternative to the legacy GPIO interface. Differences between the gpiod
and legacy gpio APIs are:

- gpio works with integers, whereas gpiod operates on opaque handlers
  which cannot be forged or used before proper acquisition
- gpiod get/set functions are aware of the active low state of a GPIO
- gpio consumers should now include <linux/gpio/consumer.h> to access
  the new interface, whereas chips drivers will use
  <linux/gpio/driver.h>

The legacy gpio API is now built as inline functions on top of gpiod.

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

1 files changed, 62 insertions, 160 deletions

diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index b309a5c0019e..00f8f0a9edcd 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -10,6 +10,8 @@
 #ifdef CONFIG_GPIOLIB
 
 #include <linux/compiler.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/consumer.h>
 
 /* Platforms may implement their GPIO interface with library code,
  * at a small performance cost for non-inlined operations and some
@@ -49,122 +51,11 @@ struct module;
 struct device_node;
 struct gpio_desc;
 
-/**
- * struct gpio_chip - abstract a GPIO controller
- * @label: for diagnostics
- * @dev: optional device providing the GPIOs
- * @owner: helps prevent removal of modules exporting active GPIOs
- * @list: links gpio_chips together for traversal
- * @request: optional hook for chip-specific activation, such as
- *      enabling module power and clock; may sleep
- * @free: optional hook for chip-specific deactivation, such as
- *      disabling module power and clock; may sleep
- * @get_direction: returns direction for signal "offset", 0=out, 1=in,
- *      (same as GPIOF_DIR_XXX), or negative error
- * @direction_input: configures signal "offset" as input, or returns error
- * @get: returns value for signal "offset"; for output signals this
- *      returns either the value actually sensed, or zero
- * @direction_output: configures signal "offset" as output, or returns error
- * @set_debounce: optional hook for setting debounce time for specified gpio in
- *      interrupt triggered gpio chips
- * @set: assigns output value for signal "offset"
- * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
- *      implementation may not sleep
- * @dbg_show: optional routine to show contents in debugfs; default code
- *      will be used when this is omitted, but custom code can show extra
- *      state (such as pullup/pulldown configuration).
- * @base: identifies the first GPIO number handled by this chip; or, if
- *      negative during registration, requests dynamic ID allocation.
- * @ngpio: the number of GPIOs handled by this controller; the last GPIO
- *      handled is (base + ngpio - 1).
- * @desc: array of ngpio descriptors. Private.
- * @can_sleep: flag must be set iff get()/set() methods sleep, as they
- *      must while accessing GPIO expander chips over I2C or SPI
- * @names: if set, must be an array of strings to use as alternative
- *      names for the GPIOs in this chip. Any entry in the array
- *      may be NULL if there is no alias for the GPIO, however the
- *      array must be @ngpio entries long.  A name can include a single printk
- *      format specifier for an unsigned int.  It is substituted by the actual
- *      number of the gpio.
- *
- * A gpio_chip can help platforms abstract various sources of GPIOs so
- * they can all be accessed through a common programing interface.
- * Example sources would be SOC controllers, FPGAs, multifunction
- * chips, dedicated GPIO expanders, and so on.
- *
- * Each chip controls a number of signals, identified in method calls
- * by "offset" values in the range 0..(@ngpio - 1).  When those signals
- * are referenced through calls like gpio_get_value(gpio), the offset
- * is calculated by subtracting @base from the gpio number.
- */
-struct gpio_chip {
-        const char              *label;
-        struct device           *dev;
-        struct module           *owner;
-        struct list_head        list;
-
-        int                     (*request)(struct gpio_chip *chip,
-                                                unsigned offset);
-        void                    (*free)(struct gpio_chip *chip,
-                                                unsigned offset);
-        int                     (*get_direction)(struct gpio_chip *chip,
-                                                unsigned offset);
-        int                     (*direction_input)(struct gpio_chip *chip,
-                                                unsigned offset);
-        int                     (*get)(struct gpio_chip *chip,
-                                                unsigned offset);
-        int                     (*direction_output)(struct gpio_chip *chip,
-                                                unsigned offset, int value);
-        int                     (*set_debounce)(struct gpio_chip *chip,
-                                                unsigned offset, unsigned debounce);
-
-        void                    (*set)(struct gpio_chip *chip,
-                                                unsigned offset, int value);
-
-        int                     (*to_irq)(struct gpio_chip *chip,
-                                                unsigned offset);
-
-        void                    (*dbg_show)(struct seq_file *s,
-                                                struct gpio_chip *chip);
-        int                     base;
-        u16                     ngpio;
-        struct gpio_desc        *desc;
-        const char              *const *names;
-        unsigned                can_sleep:1;
-        unsigned                exported:1;
-
-#if defined(CONFIG_OF_GPIO)
-        /*
-         * If CONFIG_OF is enabled, then all GPIO controllers described in the
-         * device tree automatically may have an OF translation
-         */
-        struct device_node *of_node;
-        int of_gpio_n_cells;
-        int (*of_xlate)(struct gpio_chip *gc,
-                        const struct of_phandle_args *gpiospec, u32 *flags);
-#endif
-#ifdef CONFIG_PINCTRL
-        /*
-         * If CONFIG_PINCTRL is enabled, then gpio controllers can optionally
-         * describe the actual pin range which they serve in an SoC. This
-         * information would be used by pinctrl subsystem to configure
-         * corresponding pins for gpio usage.
-         */
-        struct list_head pin_ranges;
-#endif
-};
-
-extern const char *gpiochip_is_requested(struct gpio_chip *chip,
-                        unsigned offset);
-extern struct gpio_chip *gpio_to_chip(unsigned gpio);
-
-/* add/remove chips */
-extern int gpiochip_add(struct gpio_chip *chip);
-extern int __must_check gpiochip_remove(struct gpio_chip *chip);
-extern struct gpio_chip *gpiochip_find(void *data,
-                                        int (*match)(struct gpio_chip *chip,
-                                                     void *data));
-
+/* caller holds gpio_lock *OR* gpio is marked as requested */
+static inline struct gpio_chip *gpio_to_chip(unsigned gpio)
+{
+        return gpiod_to_chip(gpio_to_desc(gpio));
+}
 
 /* Always use the library code for GPIO management calls,
  * or when sleeping may be involved.
@@ -172,25 +63,52 @@ extern struct gpio_chip *gpiochip_find(void *data,
 extern int gpio_request(unsigned gpio, const char *label);
 extern void gpio_free(unsigned gpio);
 
-extern int gpio_direction_input(unsigned gpio);
-extern int gpio_direction_output(unsigned gpio, int value);
+static inline int gpio_direction_input(unsigned gpio)
+{
+        return gpiod_direction_input(gpio_to_desc(gpio));
+}
+static inline int gpio_direction_output(unsigned gpio, int value)
+{
+        return gpiod_direction_output(gpio_to_desc(gpio), value);
+}
 
-extern int gpio_set_debounce(unsigned gpio, unsigned debounce);
+static inline int gpio_set_debounce(unsigned gpio, unsigned debounce)
+{
+        return gpiod_set_debounce(gpio_to_desc(gpio), debounce);
+}
 
-extern int gpio_get_value_cansleep(unsigned gpio);
-extern void gpio_set_value_cansleep(unsigned gpio, int value);
+static inline int gpio_get_value_cansleep(unsigned gpio)
+{
+        return gpiod_get_raw_value_cansleep(gpio_to_desc(gpio));
+}
+static inline void gpio_set_value_cansleep(unsigned gpio, int value)
+{
+        return gpiod_set_raw_value_cansleep(gpio_to_desc(gpio), value);
+}
 
 
 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
  * the GPIO is constant and refers to some always-present controller,
  * giving direct access to chip registers and tight bitbanging loops.
  */
-extern int __gpio_get_value(unsigned gpio);
-extern void __gpio_set_value(unsigned gpio, int value);
+static inline int __gpio_get_value(unsigned gpio)
+{
+        return gpiod_get_raw_value(gpio_to_desc(gpio));
+}
+static inline void __gpio_set_value(unsigned gpio, int value)
+{
+        return gpiod_set_raw_value(gpio_to_desc(gpio), value);
+}
 
-extern int __gpio_cansleep(unsigned gpio);
+static inline int __gpio_cansleep(unsigned gpio)
+{
+        return gpiod_cansleep(gpio_to_desc(gpio));
+}
 
-extern int __gpio_to_irq(unsigned gpio);
+static inline int __gpio_to_irq(unsigned gpio)
+{
+        return gpiod_to_irq(gpio_to_desc(gpio));
+}
 
 extern int gpio_lock_as_irq(struct gpio_chip *chip, unsigned int offset);
 extern void gpio_unlock_as_irq(struct gpio_chip *chip, unsigned int offset);
@@ -199,19 +117,30 @@ extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *labe
 extern int gpio_request_array(const struct gpio *array, size_t num);
 extern void gpio_free_array(const struct gpio *array, size_t num);
 
-#ifdef CONFIG_GPIO_SYSFS
-
 /*
  * A sysfs interface can be exported by individual drivers if they want,
  * but more typically is configured entirely from userspace.
  */
-extern int gpio_export(unsigned gpio, bool direction_may_change);
-extern int gpio_export_link(struct device *dev, const char *name,
-                        unsigned gpio);
-extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
-extern void gpio_unexport(unsigned gpio);
+static inline int gpio_export(unsigned gpio, bool direction_may_change)
+{
+        return gpiod_export(gpio_to_desc(gpio), direction_may_change);
+}
 
-#endif  /* CONFIG_GPIO_SYSFS */
+static inline int gpio_export_link(struct device *dev, const char *name,
+                                   unsigned gpio)
+{
+        return gpiod_export_link(dev, name, gpio_to_desc(gpio));
+}
+
+static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
+{
+        return gpiod_sysfs_set_active_low(gpio_to_desc(gpio), value);
+}
+
+static inline void gpio_unexport(unsigned gpio)
+{
+        gpiod_unexport(gpio_to_desc(gpio));
+}
 
 #ifdef CONFIG_PINCTRL
 
@@ -281,31 +210,4 @@ static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 
 #endif /* !CONFIG_GPIOLIB */
 
-#ifndef CONFIG_GPIO_SYSFS
-
-struct device;
-
-/* sysfs support is only available with gpiolib, where it's optional */
-
-static inline int gpio_export(unsigned gpio, bool direction_may_change)
-{
-        return -ENOSYS;
-}
-
-static inline int gpio_export_link(struct device *dev, const char *name,
-                                unsigned gpio)
-{
-        return -ENOSYS;
-}
-
-static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
-{
-        return -ENOSYS;
-}
-
-static inline void gpio_unexport(unsigned gpio)
-{
-}
-#endif  /* CONFIG_GPIO_SYSFS */
-
 #endif /* _ASM_GENERIC_GPIO_H */