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