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