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
   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  * ARCH_NR_GPIOS is somewhat arbitrary; it usually reflects the sum of
  21  * builtin/SoC GPIOs plus a number of GPIOs on expanders; the latter is
  22  * actually an estimate of a board-specific value.
  23  */
  24
  25 #ifndef ARCH_NR_GPIOS
  26 #define ARCH_NR_GPIOS           256
  27 #endif
  28
  29 /*
  30  * "valid" GPIO numbers are nonnegative and may be passed to
  31  * setup routines like gpio_request().  only some valid numbers
  32  * can successfully be requested and used.
  33  *
  34  * Invalid GPIO numbers are useful for indicating no-such-GPIO in
  35  * platform data and other tables.
  36  */
  37
  38 static inline bool gpio_is_valid(int number)
  39 {
  40         return number >= 0 && number < ARCH_NR_GPIOS;
  41 }
  42
  43 struct device;
  44 struct seq_file;
  45 struct module;
  46 struct device_node;
  47
  48 /**
  49  * struct gpio_chip - abstract a GPIO controller
  50  * @label: for diagnostics
  51  * @dev: optional device providing the GPIOs
  52  * @owner: helps prevent removal of modules exporting active GPIOs
  53  * @request: optional hook for chip-specific activation, such as
  54  *      enabling module power and clock; may sleep
  55  * @free: optional hook for chip-specific deactivation, such as
  56  *      disabling module power and clock; may sleep
  57  * @direction_input: configures signal "offset" as input, or returns error
  58  * @get: returns value for signal "offset"; for output signals this
  59  *      returns either the value actually sensed, or zero
  60  * @direction_output: configures signal "offset" as output, or returns error
  61  * @set: assigns output value for signal "offset"
  62  * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
  63  *      implementation may not sleep
  64  * @dbg_show: optional routine to show contents in debugfs; default code
  65  *      will be used when this is omitted, but custom code can show extra
  66  *      state (such as pullup/pulldown configuration).
  67  * @base: identifies the first GPIO number handled by this chip; or, if
  68  *      negative during registration, requests dynamic ID allocation.
  69  * @ngpio: the number of GPIOs handled by this controller; the last GPIO
  70  *      handled is (base + ngpio - 1).
  71  * @can_sleep: flag must be set iff get()/set() methods sleep, as they
  72  *      must while accessing GPIO expander chips over I2C or SPI
  73  * @names: if set, must be an array of strings to use as alternative
  74  *      names for the GPIOs in this chip. Any entry in the array
  75  *      may be NULL if there is no alias for the GPIO, however the
  76  *      array must be @ngpio entries long.  A name can include a single printk
  77  *      format specifier for an unsigned int.  It is substituted by the actual
  78  *      number of the gpio.
  79  *
  80  * A gpio_chip can help platforms abstract various sources of GPIOs so
  81  * they can all be accessed through a common programing interface.
  82  * Example sources would be SOC controllers, FPGAs, multifunction
  83  * chips, dedicated GPIO expanders, and so on.
  84  *
  85  * Each chip controls a number of signals, identified in method calls
  86  * by "offset" values in the range 0..(@ngpio - 1).  When those signals
  87  * are referenced through calls like gpio_get_value(gpio), the offset
  88  * is calculated by subtracting @base from the gpio number.
  89  */
  90 struct gpio_chip {
  91         const char              *label;
  92         struct device           *dev;
  93         struct module           *owner;
  94
  95         int                     (*request)(struct gpio_chip *chip,
  96                                                 unsigned offset);
  97         void                    (*free)(struct gpio_chip *chip,
  98                                                 unsigned offset);
  99
 100         int                     (*direction_input)(struct gpio_chip *chip,
 101                                                 unsigned offset);
 102         int                     (*get)(struct gpio_chip *chip,
 103                                                 unsigned offset);
 104         int                     (*direction_output)(struct gpio_chip *chip,
 105                                                 unsigned offset, int value);
 106         int                     (*set_debounce)(struct gpio_chip *chip,
 107                                                 unsigned offset, unsigned debounce);
 108
 109         void                    (*set)(struct gpio_chip *chip,
 110                                                 unsigned offset, int value);
 111
 112         int                     (*to_irq)(struct gpio_chip *chip,
 113                                                 unsigned offset);
 114
 115         void                    (*dbg_show)(struct seq_file *s,
 116                                                 struct gpio_chip *chip);
 117         int                     base;
 118         u16                     ngpio;
 119         const char              *const *names;
 120         unsigned                can_sleep:1;
 121         unsigned                exported:1;
 122
 123 #if defined(CONFIG_OF_GPIO)
 124         /*
 125          * If CONFIG_OF is enabled, then all GPIO controllers described in the
 126          * device tree automatically may have an OF translation
 127          */
 128         struct device_node *of_node;
 129         int of_gpio_n_cells;
 130         int (*of_xlate)(struct gpio_chip *gc, struct device_node *np,
 131                         const void *gpio_spec, u32 *flags);
 132 #endif
 133 };
 134
 135 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
 136                         unsigned offset);
 137 extern int __must_check gpiochip_reserve(int start, int ngpio);
 138
 139 /* add/remove chips */
 140 extern int gpiochip_add(struct gpio_chip *chip);
 141 extern int __must_check gpiochip_remove(struct gpio_chip *chip);
 142 extern struct gpio_chip *gpiochip_find(void *data,
 143                                         int (*match)(struct gpio_chip *chip,
 144                                                      void *data));
 145
 146
 147 /* Always use the library code for GPIO management calls,
 148  * or when sleeping may be involved.
 149  */
 150 extern int gpio_request(unsigned gpio, const char *label);
 151 extern void gpio_free(unsigned gpio);
 152
 153 extern int gpio_direction_input(unsigned gpio);
 154 extern int gpio_direction_output(unsigned gpio, int value);
 155
 156 extern int gpio_set_debounce(unsigned gpio, unsigned debounce);
 157
 158 extern int gpio_get_value_cansleep(unsigned gpio);
 159 extern void gpio_set_value_cansleep(unsigned gpio, int value);
 160
 161
 162 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
 163  * the GPIO is constant and refers to some always-present controller,
 164  * giving direct access to chip registers and tight bitbanging loops.
 165  */
 166 extern int __gpio_get_value(unsigned gpio);
 167 extern void __gpio_set_value(unsigned gpio, int value);
 168
 169 extern int __gpio_cansleep(unsigned gpio);
 170
 171 extern int __gpio_to_irq(unsigned gpio);
 172
 173 /**
 174  * struct gpio - a structure describing a GPIO with configuration
 175  * @gpio:       the GPIO number
 176  * @flags:      GPIO configuration as specified by GPIOF_*
 177  * @label:      a literal description string of this GPIO
 178  */
 179 struct gpio {
 180         unsigned        gpio;
 181         unsigned long   flags;
 182         const char      *label;
 183 };
 184
 185 extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
 186 extern int gpio_request_array(const struct gpio *array, size_t num);
 187 extern void gpio_free_array(const struct gpio *array, size_t num);
 188
 189 #ifdef CONFIG_GPIO_SYSFS
 190
 191 /*
 192  * A sysfs interface can be exported by individual drivers if they want,
 193  * but more typically is configured entirely from userspace.
 194  */
 195 extern int gpio_export(unsigned gpio, bool direction_may_change);
 196 extern int gpio_export_link(struct device *dev, const char *name,
 197                         unsigned gpio);
 198 extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
 199 extern void gpio_unexport(unsigned gpio);
 200
 201 #endif  /* CONFIG_GPIO_SYSFS */
 202
 203 #else   /* !CONFIG_GPIOLIB */
 204
 205 static inline bool gpio_is_valid(int number)
 206 {
 207         /* only non-negative numbers are valid */
 208         return number >= 0;
 209 }
 210
 211 /* platforms that don't directly support access to GPIOs through I2C, SPI,
 212  * or other blocking infrastructure can use these wrappers.
 213  */
 214
 215 static inline int gpio_cansleep(unsigned gpio)
 216 {
 217         return 0;
 218 }
 219
 220 static inline int gpio_get_value_cansleep(unsigned gpio)
 221 {
 222         might_sleep();
 223         return gpio_get_value(gpio);
 224 }
 225
 226 static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 227 {
 228         might_sleep();
 229         gpio_set_value(gpio, value);
 230 }
 231
 232 #endif /* !CONFIG_GPIOLIB */
 233
 234 #ifndef CONFIG_GPIO_SYSFS
 235
 236 struct device;
 237
 238 /* sysfs support is only available with gpiolib, where it's optional */
 239
 240 static inline int gpio_export(unsigned gpio, bool direction_may_change)
 241 {
 242         return -ENOSYS;
 243 }
 244
 245 static inline int gpio_export_link(struct device *dev, const char *name,
 246                                 unsigned gpio)
 247 {
 248         return -ENOSYS;
 249 }
 250
 251 static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
 252 {
 253         return -ENOSYS;
 254 }
 255
 256 static inline void gpio_unexport(unsigned gpio)
 257 {
 258 }
 259 #endif  /* CONFIG_GPIO_SYSFS */
 260
 261 #endif /* _ASM_GENERIC_GPIO_H */