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Diffstat (limited to 'include/asm-generic/gpio.h')
| -rw-r--r-- | include/asm-generic/gpio.h | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h new file mode 100644 index 00000000..70ed842f --- /dev/null +++ b/include/asm-generic/gpio.h @@ -0,0 +1,257 @@ +#ifndef _ASM_GENERIC_GPIO_H +#define _ASM_GENERIC_GPIO_H + +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/errno.h> +#include <linux/of.h> + +#ifdef CONFIG_GPIOLIB + +#include <linux/compiler.h> + +/* Platforms may implement their GPIO interface with library code, + * at a small performance cost for non-inlined operations and some + * extra memory (for code and for per-GPIO table entries). + * + * While the GPIO programming interface defines valid GPIO numbers + * to be in the range 0..MAX_INT, this library restricts them to the + * smaller range 0..ARCH_NR_GPIOS-1. + * + * ARCH_NR_GPIOS is somewhat arbitrary; it usually reflects the sum of + * builtin/SoC GPIOs plus a number of GPIOs on expanders; the latter is + * actually an estimate of a board-specific value. + */ + +#ifndef ARCH_NR_GPIOS +#define ARCH_NR_GPIOS 256 +#endif + +/* + * "valid" GPIO numbers are nonnegative and may be passed to + * setup routines like gpio_request(). only some valid numbers + * can successfully be requested and used. + * + * Invalid GPIO numbers are useful for indicating no-such-GPIO in + * platform data and other tables. + */ + +static inline bool gpio_is_valid(int number) +{ + return number >= 0 && number < ARCH_NR_GPIOS; +} + +struct device; +struct gpio; +struct seq_file; +struct module; +struct device_node; + +/** + * 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 + * @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 + * @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: 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). + * @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; + + int (*request)(struct gpio_chip *chip, + unsigned offset); + void (*free)(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; + 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 +}; + +extern const char *gpiochip_is_requested(struct gpio_chip *chip, + unsigned offset); +extern struct gpio_chip *gpio_to_chip(unsigned gpio); +extern int __must_check gpiochip_reserve(int start, int ngpio); + +/* 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(const void *data, + int (*match)(struct gpio_chip *chip, + const void *data)); + + +/* Always use the library code for GPIO management calls, + * or when sleeping may be involved. + */ +extern int gpio_request(unsigned gpio, const char *label); +extern void gpio_free(unsigned gpio); +extern int gpio_re_enabled(unsigned gpio); + +extern int gpio_direction_input(unsigned gpio); +extern int gpio_direction_output(unsigned gpio, int value); + +extern int gpio_set_debounce(unsigned gpio, unsigned debounce); + +extern int gpio_get_value_cansleep(unsigned gpio); +extern void gpio_set_value_cansleep(unsigned gpio, int 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); + +extern int __gpio_cansleep(unsigned gpio); + +extern int __gpio_to_irq(unsigned gpio); + +extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label); +extern int gpio_request_array(const struct gpio *array, size_t num); +extern void gpio_free_array(const struct gpio *array, size_t num); + +/* bindings for managed devices that want to request gpios */ +int devm_gpio_request(struct device *dev, unsigned gpio, const char *label); +void devm_gpio_free(struct device *dev, unsigned int gpio); + +#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); + +#endif /* CONFIG_GPIO_SYSFS */ + +#else /* !CONFIG_GPIOLIB */ + +static inline bool gpio_is_valid(int number) +{ + /* only non-negative numbers are valid */ + return number >= 0; +} + +/* platforms that don't directly support access to GPIOs through I2C, SPI, + * or other blocking infrastructure can use these wrappers. + */ + +static inline int gpio_cansleep(unsigned gpio) +{ + return 0; +} + +static inline int gpio_get_value_cansleep(unsigned gpio) +{ + might_sleep(); + return __gpio_get_value(gpio); +} + +static inline void gpio_set_value_cansleep(unsigned gpio, int value) +{ + might_sleep(); + __gpio_set_value(gpio, 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 */ |