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