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 int gpio_is_valid(int number)
  39 {
  40         return ((unsigned)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  * @config: set/get a certain custom parameter for the GPIO
  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         void                    (*set)(struct gpio_chip *chip,
 110                                                 unsigned offset, int value);
 111         int                     (*to_irq)(struct gpio_chip *chip,
 112                                                 unsigned offset);
 113         int                     (*config)(struct gpio_chip *chip,
 114                                                 unsigned offset,
 115                                                 u16 param,
 116                                                 unsigned long *data);
 117
 118         void                    (*dbg_show)(struct seq_file *s,
 119                                                 struct gpio_chip *chip);
 120         int                     base;
 121         u16                     ngpio;
 122         const char              *const *names;
 123         unsigned                can_sleep:1;
 124         unsigned                exported:1;
 125
 126 #if defined(CONFIG_OF_GPIO)
 127         /*
 128          * If CONFIG_OF is enabled, then all GPIO controllers described in the
 129          * device tree automatically may have an OF translation
 130          */
 131         struct device_node *of_node;
 132         int of_gpio_n_cells;
 133         int (*of_xlate)(struct gpio_chip *gc, struct device_node *np,
 134                         const void *gpio_spec, u32 *flags);
 135 #endif
 136 };
 137
 138 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
 139                         unsigned offset);
 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 extern int gpio_config(unsigned gpio, u16 param, unsigned long *data);
 165
 166 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
 167  * the GPIO is constant and refers to some always-present controller,
 168  * giving direct access to chip registers and tight bitbanging loops.
 169  */
 170 extern int __gpio_get_value(unsigned gpio);
 171 extern void __gpio_set_value(unsigned gpio, int value);
 172
 173 extern int __gpio_cansleep(unsigned gpio);
 174
 175 extern int __gpio_to_irq(unsigned gpio);
 176
 177 #define GPIOF_DIR_OUT   (0 << 0)
 178 #define GPIOF_DIR_IN    (1 << 0)
 179
 180 #define GPIOF_INIT_LOW  (0 << 1)
 181 #define GPIOF_INIT_HIGH (1 << 1)
 182
 183 #define GPIOF_IN                (GPIOF_DIR_IN)
 184 #define GPIOF_OUT_INIT_LOW      (GPIOF_DIR_OUT | GPIOF_INIT_LOW)
 185 #define GPIOF_OUT_INIT_HIGH     (GPIOF_DIR_OUT | GPIOF_INIT_HIGH)
 186
 187 /**
 188  * struct gpio - a structure describing a GPIO with configuration
 189  * @gpio:       the GPIO number
 190  * @flags:      GPIO configuration as specified by GPIOF_*
 191  * @label:      a literal description string of this GPIO
 192  */
 193 struct gpio {
 194         unsigned        gpio;
 195         unsigned long   flags;
 196         const char      *label;
 197 };
 198
 199 extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
 200 extern int gpio_request_array(struct gpio *array, size_t num);
 201 extern void gpio_free_array(struct gpio *array, size_t num);
 202
 203 #ifdef CONFIG_GPIO_SYSFS
 204
 205 /*
 206  * A sysfs interface can be exported by individual drivers if they want,
 207  * but more typically is configured entirely from userspace.
 208  */
 209 extern int gpio_export(unsigned gpio, bool direction_may_change);
 210 extern int gpio_export_link(struct device *dev, const char *name,
 211                         unsigned gpio);
 212 extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
 213 extern void gpio_unexport(unsigned gpio);
 214
 215 #endif  /* CONFIG_GPIO_SYSFS */
 216
 217 #else   /* !CONFIG_GPIOLIB */
 218
 219 static inline int gpio_is_valid(int number)
 220 {
 221         /* only non-negative numbers are valid */
 222         return number >= 0;
 223 }
 224
 225 /* platforms that don't directly support access to GPIOs through I2C, SPI,
 226  * or other blocking infrastructure can use these wrappers.
 227  */
 228
 229 static inline int gpio_cansleep(unsigned gpio)
 230 {
 231         return 0;
 232 }
 233
 234 static inline int gpio_get_value_cansleep(unsigned gpio)
 235 {
 236         might_sleep();
 237         return gpio_get_value(gpio);
 238 }
 239
 240 static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 241 {
 242         might_sleep();
 243         gpio_set_value(gpio, value);
 244 }
 245
 246 #endif /* !CONFIG_GPIOLIB */
 247
 248 #ifndef CONFIG_GPIO_SYSFS
 249
 250 struct device;
 251
 252 /* sysfs support is only available with gpiolib, where it's optional */
 253
 254 static inline int gpio_export(unsigned gpio, bool direction_may_change)
 255 {
 256         return -ENOSYS;
 257 }
 258
 259 static inline int gpio_export_link(struct device *dev, const char *name,
 260                                 unsigned gpio)
 261 {
 262         return -ENOSYS;
 263 }
 264
 265 static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
 266 {
 267         return -ENOSYS;
 268 }
 269
 270 static inline void gpio_unexport(unsigned gpio)
 271 {
 272 }
 273 #endif  /* CONFIG_GPIO_SYSFS */
 274
 275 #endif /* _ASM_GENERIC_GPIO_H */