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>
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
new file mode 100644
index 0000000..5dc172c
--- /dev/null
+++ b/include/linux/gpio/driver.h
@@ -0,0 +1,127 @@
+#ifndef __LINUX_GPIO_DRIVER_H
+#define __LINUX_GPIO_DRIVER_H
+
+#include <linux/types.h>
+
+struct device;
+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
+ * @direction_output: configures signal "offset" as output, or returns error
+ * @get: returns value for signal "offset"; for output signals this
+ * returns either the value actually sensed, or zero
+ * @set: assigns output value for signal "offset"
+ * @set_debounce: optional hook for setting debounce time for specified gpio in
+ * interrupt triggered gpio chips
+ * @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 (*direction_output)(struct gpio_chip *chip,
+ unsigned offset, int value);
+ int (*get)(struct gpio_chip *chip,
+ unsigned offset);
+ void (*set)(struct gpio_chip *chip,
+ unsigned offset, int value);
+ int (*set_debounce)(struct gpio_chip *chip,
+ unsigned offset,
+ unsigned debounce);
+
+ 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);
+
+/* 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));
+
+/* lock/unlock as IRQ */
+int gpiod_lock_as_irq(struct gpio_desc *desc);
+void gpiod_unlock_as_irq(struct gpio_desc *desc);
+
+#endif