diff options
Diffstat (limited to 'include/asm-generic')
| -rw-r--r-- | include/asm-generic/gpio.h | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index 2d0aab1d8611..f29a502f4a6c 100644 --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -1,6 +1,102 @@ #ifndef _ASM_GENERIC_GPIO_H #define _ASM_GENERIC_GPIO_H +#ifdef CONFIG_HAVE_GPIO_LIB + +/* 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. + */ + +#ifndef ARCH_NR_GPIOS +#define ARCH_NR_GPIOS 256 +#endif + +struct seq_file; + +/** + * struct gpio_chip - abstract a GPIO controller + * @label: for diagnostics + * @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" + * @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 + * + * 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 { + char *label; + + 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); + void (*set)(struct gpio_chip *chip, + unsigned offset, int value); + void (*dbg_show)(struct seq_file *s, + struct gpio_chip *chip); + int base; + u16 ngpio; + unsigned can_sleep:1; +}; + +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); + + +/* 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_direction_input(unsigned gpio); +extern int gpio_direction_output(unsigned gpio, int value); + +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); + + +#else + /* platforms that don't directly support access to GPIOs through I2C, SPI, * or other blocking infrastructure can use these wrappers. */ @@ -22,4 +118,6 @@ static inline void gpio_set_value_cansleep(unsigned gpio, int value) gpio_set_value(gpio, value); } +#endif + #endif /* _ASM_GENERIC_GPIO_H */ |