include/asm-generic/gpio.h

   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 #include <linux/of.h>
   8
   9 #ifdef CONFIG_GPIOLIB
  10
  11 #include <linux/compiler.h>
  12
  13 /* Platforms may implement their GPIO interface with library code,
  14  * at a small performance cost for non-inlined operations and some
  15  * extra memory (for code and for per-GPIO table entries).
  16  *
  17  * While the GPIO programming interface defines valid GPIO numbers
  18  * to be in the range 0..MAX_INT, this library restricts them to the
  19  * smaller range 0..ARCH_NR_GPIOS-1.
  20  *
  21  * ARCH_NR_GPIOS is somewhat arbitrary; it usually reflects the sum of
  22  * builtin/SoC GPIOs plus a number of GPIOs on expanders; the latter is
  23  * actually an estimate of a board-specific value.
  24  */
  25
  26 #ifndef ARCH_NR_GPIOS
  27 #define ARCH_NR_GPIOS           256
  28 #endif
  29
  30 /*
  31  * "valid" GPIO numbers are nonnegative and may be passed to
  32  * setup routines like gpio_request().  only some valid numbers
  33  * can successfully be requested and used.
  34  *
  35  * Invalid GPIO numbers are useful for indicating no-such-GPIO in
  36  * platform data and other tables.
  37  */
  38
  39 static inline bool gpio_is_valid(int number)
  40 {
  41         return number >= 0 && number < ARCH_NR_GPIOS;
  42 }
  43
  44 struct device;
  45 struct gpio;
  46 struct seq_file;
  47 struct module;
  48 struct device_node;
  49
  50 /**
  51  * struct gpio_chip - abstract a GPIO controller
  52  * @label: for diagnostics
  53  * @dev: optional device providing the GPIOs
  54  * @owner: helps prevent removal of modules exporting active GPIOs
  55  * @request: optional hook for chip-specific activation, such as
  56  *      enabling module power and clock; may sleep
  57  * @free: optional hook for chip-specific deactivation, such as
  58  *      disabling module power and clock; may sleep
  59  * @direction_input: configures signal "offset" as input, or returns error
  60  * @get: returns value for signal "offset"; for output signals this
  61  *      returns either the value actually sensed, or zero
  62  * @direction_output: configures signal "offset" as output, or returns error
  63  * @set: assigns output value for signal "offset"
  64  * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
  65  *      implementation may not sleep
  66  * @dbg_show: optional routine to show contents in debugfs; default code
  67  *      will be used when this is omitted, but custom code can show extra
  68  *      state (such as pullup/pulldown configuration).
  69  * @base: identifies the first GPIO number handled by this chip; or, if
  70  *      negative during registration, requests dynamic ID allocation.
  71  * @ngpio: the number of GPIOs handled by this controller; the last GPIO
  72  *      handled is (base + ngpio - 1).
  73  * @can_sleep: flag must be set iff get()/set() methods sleep, as they
  74  *      must while accessing GPIO expander chips over I2C or SPI
  75  * @names: if set, must be an array of strings to use as alternative
  76  *      names for the GPIOs in this chip. Any entry in the array
  77  *      may be NULL if there is no alias for the GPIO, however the
  78  *      array must be @ngpio entries long.  A name can include a single printk
  79  *      format specifier for an unsigned int.  It is substituted by the actual
  80  *      number of the gpio.
  81  *
  82  * A gpio_chip can help platforms abstract various sources of GPIOs so
  83  * they can all be accessed through a common programing interface.
  84  * Example sources would be SOC controllers, FPGAs, multifunction
  85  * chips, dedicated GPIO expanders, and so on.
  86  *
  87  * Each chip controls a number of signals, identified in method calls
  88  * by "offset" values in the range 0..(@ngpio - 1).  When those signals
  89  * are referenced through calls like gpio_get_value(gpio), the offset
  90  * is calculated by subtracting @base from the gpio number.
  91  */
  92 struct gpio_chip {
  93         const char              *label;
  94         struct device           *dev;
  95         struct module           *owner;
  96
  97         int                     (*request)(struct gpio_chip *chip,
  98                                                 unsigned offset);
  99         void                    (*free)(struct gpio_chip *chip,
 100                                                 unsigned offset);
 101
 102         int                     (*direction_input)(struct gpio_chip *chip,
 103                                                 unsigned offset);
 104         int                     (*get)(struct gpio_chip *chip,
 105                                                 unsigned offset);
 106         int                     (*direction_output)(struct gpio_chip *chip,
 107                                                 unsigned offset, int value);
 108         int                     (*set_debounce)(struct gpio_chip *chip,
 109                                                 unsigned offset, unsigned debounce);
 110
 111         void                    (*set)(struct gpio_chip *chip,
 112                                                 unsigned offset, int value);
 113
 114         int                     (*to_irq)(struct gpio_chip *chip,
 115                                                 unsigned offset);
 116
 117         void                    (*dbg_show)(struct seq_file *s,
 118                                                 struct gpio_chip *chip);
 119         int                     base;
 120         u16                     ngpio;
 121         const char              *const *names;
 122         unsigned                can_sleep:1;
 123         unsigned                exported:1;
 124
 125 #if defined(CONFIG_OF_GPIO)
 126         /*
 127          * If CONFIG_OF is enabled, then all GPIO controllers described in the
 128          * device tree automatically may have an OF translation
 129          */
 130         struct device_node *of_node;
 131         int of_gpio_n_cells;
 132         int (*of_xlate)(struct gpio_chip *gc,
 133                         const struct of_phandle_args *gpiospec, u32 *flags);
 134 #endif
 135 };
 136
 137 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
 138                         unsigned offset);
 139 extern struct gpio_chip *gpio_to_chip(unsigned gpio);
 140 extern int __must_check gpiochip_reserve(int start, int ngpio);
 141
 142 /* add/remove chips */
 143 extern int gpiochip_add(struct gpio_chip *chip);
 144 extern int __must_check gpiochip_remove(struct gpio_chip *chip);
 145 extern struct gpio_chip *gpiochip_find(void *data,
 146                                         int (*match)(struct gpio_chip *chip,
 147                                                      void *data));
 148
 149
 150 /* Always use the library code for GPIO management calls,
 151  * or when sleeping may be involved.
 152  */
 153 extern int gpio_request(unsigned gpio, const char *label);
 154 extern void gpio_free(unsigned gpio);
 155
 156 extern int gpio_direction_input(unsigned gpio);
 157 extern int gpio_direction_output(unsigned gpio, int value);
 158
 159 extern int gpio_set_debounce(unsigned gpio, unsigned debounce);
 160
 161 extern int gpio_get_value_cansleep(unsigned gpio);
 162 extern void gpio_set_value_cansleep(unsigned gpio, int value);
 163
 164
 165 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
 166  * the GPIO is constant and refers to some always-present controller,
 167  * giving direct access to chip registers and tight bitbanging loops.
 168  */
 169 extern int __gpio_get_value(unsigned gpio);
 170 extern void __gpio_set_value(unsigned gpio, int value);
 171
 172 extern int __gpio_cansleep(unsigned gpio);
 173
 174 extern int __gpio_to_irq(unsigned gpio);
 175
 176 extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
 177 extern int gpio_request_array(const struct gpio *array, size_t num);
 178 extern void gpio_free_array(const struct gpio *array, size_t num);
 179
 180 /* bindings for managed devices that want to request gpios */
 181 int devm_gpio_request(struct device *dev, unsigned gpio, const char *label);
 182 void devm_gpio_free(struct device *dev, unsigned int gpio);
 183
 184 #ifdef CONFIG_GPIO_SYSFS
 185
 186 /*
 187  * A sysfs interface can be exported by individual drivers if they want,
 188  * but more typically is configured entirely from userspace.
 189  */
 190 extern int gpio_export(unsigned gpio, bool direction_may_change);
 191 extern int gpio_export_link(struct device *dev, const char *name,
 192                         unsigned gpio);
 193 extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
 194 extern void gpio_unexport(unsigned gpio);
 195
 196 #endif  /* CONFIG_GPIO_SYSFS */
 197
 198 #else   /* !CONFIG_GPIOLIB */
 199
 200 static inline bool gpio_is_valid(int number)
 201 {
 202         /* only non-negative numbers are valid */
 203         return number >= 0;
 204 }
 205
 206 /* platforms that don't directly support access to GPIOs through I2C, SPI,
 207  * or other blocking infrastructure can use these wrappers.
 208  */
 209
 210 static inline int gpio_cansleep(unsigned gpio)
 211 {
 212         return 0;
 213 }
 214
 215 static inline int gpio_get_value_cansleep(unsigned gpio)
 216 {
 217         might_sleep();
 218         return __gpio_get_value(gpio);
 219 }
 220
 221 static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 222 {
 223         might_sleep();
 224         __gpio_set_value(gpio, value);
 225 }
 226
 227 #endif /* !CONFIG_GPIOLIB */
 228
 229 #ifndef CONFIG_GPIO_SYSFS
 230
 231 struct device;
 232
 233 /* sysfs support is only available with gpiolib, where it's optional */
 234
 235 static inline int gpio_export(unsigned gpio, bool direction_may_change)
 236 {
 237         return -ENOSYS;
 238 }
 239
 240 static inline int gpio_export_link(struct device *dev, const char *name,
 241                                 unsigned gpio)
 242 {
 243         return -ENOSYS;
 244 }
 245
 246 static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
 247 {
 248         return -ENOSYS;
 249 }
 250
 251 static inline void gpio_unexport(unsigned gpio)
 252 {
 253 }
 254 #endif  /* CONFIG_GPIO_SYSFS */
 255
 256 #endif /* _ASM_GENERIC_GPIO_H */