1#ifndef _ASM_GENERIC_GPIO_H 2#define _ASM_GENERIC_GPIO_H 3 4#include <linux/kernel.h> 5#include <linux/types.h> 6#include <linux/errno.h> 7 8#ifdef CONFIG_GPIOLIB 9 10#include <linux/compiler.h> 11 12/* Platforms may implement their GPIO interface with library code, 13 * at a small performance cost for non-inlined operations and some 14 * extra memory (for code and for per-GPIO table entries). 15 * 16 * While the GPIO programming interface defines valid GPIO numbers 17 * to be in the range 0..MAX_INT, this library restricts them to the 18 * smaller range 0..ARCH_NR_GPIOS-1. 19 */ 20 21#ifndef ARCH_NR_GPIOS 22#define ARCH_NR_GPIOS 256 23#endif 24 25static inline int gpio_is_valid(int number) 26{ 27 /* only some non-negative numbers are valid */ 28 return ((unsigned)number) < ARCH_NR_GPIOS; 29} 30 31struct seq_file; 32struct module; 33 34/** 35 * struct gpio_chip - abstract a GPIO controller 36 * @label: for diagnostics 37 * @dev: optional device providing the GPIOs 38 * @owner: helps prevent removal of modules exporting active GPIOs 39 * @request: optional hook for chip-specific activation, such as 40 * enabling module power and clock; may sleep 41 * @free: optional hook for chip-specific deactivation, such as 42 * disabling module power and clock; may sleep 43 * @direction_input: configures signal "offset" as input, or returns error 44 * @get: returns value for signal "offset"; for output signals this 45 * returns either the value actually sensed, or zero 46 * @direction_output: configures signal "offset" as output, or returns error 47 * @set: assigns output value for signal "offset" 48 * @to_irq: optional hook supporting non-static gpio_to_irq() mappings; 49 * implementation may not sleep 50 * @dbg_show: optional routine to show contents in debugfs; default code 51 * will be used when this is omitted, but custom code can show extra 52 * state (such as pullup/pulldown configuration). 53 * @base: identifies the first GPIO number handled by this chip; or, if 54 * negative during registration, requests dynamic ID allocation. 55 * @ngpio: the number of GPIOs handled by this controller; the last GPIO 56 * handled is (base + ngpio - 1). 57 * @can_sleep: flag must be set iff get()/set() methods sleep, as they 58 * must while accessing GPIO expander chips over I2C or SPI 59 * @names: if set, must be an array of strings to use as alternative 60 * names for the GPIOs in this chip. Any entry in the array 61 * may be NULL if there is no alias for the GPIO, however the 62 * array must be @ngpio entries long. 63 * 64 * A gpio_chip can help platforms abstract various sources of GPIOs so 65 * they can all be accessed through a common programing interface. 66 * Example sources would be SOC controllers, FPGAs, multifunction 67 * chips, dedicated GPIO expanders, and so on. 68 * 69 * Each chip controls a number of signals, identified in method calls 70 * by "offset" values in the range 0..(@ngpio - 1). When those signals 71 * are referenced through calls like gpio_get_value(gpio), the offset 72 * is calculated by subtracting @base from the gpio number. 73 */ 74struct gpio_chip { 75 const char *label; 76 struct device *dev; 77 struct module *owner; 78 79 int (*request)(struct gpio_chip *chip, 80 unsigned offset); 81 void (*free)(struct gpio_chip *chip, 82 unsigned offset); 83 84 int (*direction_input)(struct gpio_chip *chip, 85 unsigned offset); 86 int (*get)(struct gpio_chip *chip, 87 unsigned offset); 88 int (*direction_output)(struct gpio_chip *chip, 89 unsigned offset, int value); 90 void (*set)(struct gpio_chip *chip, 91 unsigned offset, int value); 92 93 int (*to_irq)(struct gpio_chip *chip, 94 unsigned offset); 95 96 void (*dbg_show)(struct seq_file *s, 97 struct gpio_chip *chip); 98 int base; 99 u16 ngpio; 100 char **names; 101 unsigned can_sleep:1; 102 unsigned exported:1; 103}; 104 105extern const char *gpiochip_is_requested(struct gpio_chip *chip, 106 unsigned offset); 107extern int __must_check gpiochip_reserve(int start, int ngpio); 108 109/* add/remove chips */ 110extern int gpiochip_add(struct gpio_chip *chip); 111extern int __must_check gpiochip_remove(struct gpio_chip *chip); 112 113 114/* Always use the library code for GPIO management calls, 115 * or when sleeping may be involved. 116 */ 117extern int gpio_request(unsigned gpio, const char *label); 118extern void gpio_free(unsigned gpio); 119 120extern int gpio_direction_input(unsigned gpio); 121extern int gpio_direction_output(unsigned gpio, int value); 122 123extern int gpio_get_value_cansleep(unsigned gpio); 124extern void gpio_set_value_cansleep(unsigned gpio, int value); 125 126 127/* A platform's <asm/gpio.h> code may want to inline the I/O calls when 128 * the GPIO is constant and refers to some always-present controller, 129 * giving direct access to chip registers and tight bitbanging loops. 130 */ 131extern int __gpio_get_value(unsigned gpio); 132extern void __gpio_set_value(unsigned gpio, int value); 133 134extern int __gpio_cansleep(unsigned gpio); 135 136extern int __gpio_to_irq(unsigned gpio); 137 138#ifdef CONFIG_GPIO_SYSFS 139 140/* 141 * A sysfs interface can be exported by individual drivers if they want, 142 * but more typically is configured entirely from userspace. 143 */ 144extern int gpio_export(unsigned gpio, bool direction_may_change); 145extern int gpio_export_link(struct device *dev, const char *name, 146 unsigned gpio); 147extern void gpio_unexport(unsigned gpio); 148 149#endif /* CONFIG_GPIO_SYSFS */ 150 151#else /* !CONFIG_HAVE_GPIO_LIB */ 152 153static inline int gpio_is_valid(int number) 154{ 155 /* only non-negative numbers are valid */ 156 return number >= 0; 157} 158 159/* platforms that don't directly support access to GPIOs through I2C, SPI, 160 * or other blocking infrastructure can use these wrappers. 161 */ 162 163static inline int gpio_cansleep(unsigned gpio) 164{ 165 return 0; 166} 167 168static inline int gpio_get_value_cansleep(unsigned gpio) 169{ 170 might_sleep(); 171 return gpio_get_value(gpio); 172} 173 174static inline void gpio_set_value_cansleep(unsigned gpio, int value) 175{ 176 might_sleep(); 177 gpio_set_value(gpio, value); 178} 179 180#endif /* !CONFIG_HAVE_GPIO_LIB */ 181 182#ifndef CONFIG_GPIO_SYSFS 183 184/* sysfs support is only available with gpiolib, where it's optional */ 185 186static inline int gpio_export(unsigned gpio, bool direction_may_change) 187{ 188 return -ENOSYS; 189} 190 191static inline int gpio_export_link(struct device *dev, const char *name, 192 unsigned gpio) 193{ 194 return -ENOSYS; 195} 196 197static inline void gpio_unexport(unsigned gpio) 198{ 199} 200#endif /* CONFIG_GPIO_SYSFS */ 201 202#endif /* _ASM_GENERIC_GPIO_H */ 203