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.
  64  *
  65  * A gpio_chip can help platforms abstract various sources of GPIOs so
  66  * they can all be accessed through a common programing interface.
  67  * Example sources would be SOC controllers, FPGAs, multifunction
  68  * chips, dedicated GPIO expanders, and so on.
  69  *
  70  * Each chip controls a number of signals, identified in method calls
  71  * by "offset" values in the range 0..(@ngpio - 1).  When those signals
  72  * are referenced through calls like gpio_get_value(gpio), the offset
  73  * is calculated by subtracting @base from the gpio number.
  74  */
  75 struct gpio_chip {
  76         const char              *label;
  77         struct device           *dev;
  78         struct module           *owner;
  79
  80         int                     (*request)(struct gpio_chip *chip,
  81                                                 unsigned offset);
  82         void                    (*free)(struct gpio_chip *chip,
  83                                                 unsigned offset);
  84
  85         int                     (*direction_input)(struct gpio_chip *chip,
  86                                                 unsigned offset);
  87         int                     (*get)(struct gpio_chip *chip,
  88                                                 unsigned offset);
  89         int                     (*direction_output)(struct gpio_chip *chip,
  90                                                 unsigned offset, int value);
  91         void                    (*set)(struct gpio_chip *chip,
  92                                                 unsigned offset, int value);
  93
  94         int                     (*to_irq)(struct gpio_chip *chip,
  95                                                 unsigned offset);
  96
  97         void                    (*dbg_show)(struct seq_file *s,
  98                                                 struct gpio_chip *chip);
  99         int                     base;
 100         u16                     ngpio;
 101         char                    **names;
 102         unsigned                can_sleep:1;
 103         unsigned                exported:1;
 104 };
 105
 106 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
 107                         unsigned offset);
 108 extern int __must_check gpiochip_reserve(int start, int ngpio);
 109
 110 /* add/remove chips */
 111 extern int gpiochip_add(struct gpio_chip *chip);
 112 extern int __must_check gpiochip_remove(struct gpio_chip *chip);
 113
 114
 115 /* Always use the library code for GPIO management calls,
 116  * or when sleeping may be involved.
 117  */
 118 extern int gpio_request(unsigned gpio, const char *label);
 119 extern void gpio_free(unsigned gpio);
 120
 121 extern int gpio_direction_input(unsigned gpio);
 122 extern int gpio_direction_output(unsigned gpio, int value);
 123
 124 extern int gpio_get_value_cansleep(unsigned gpio);
 125 extern void gpio_set_value_cansleep(unsigned gpio, int value);
 126
 127
 128 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
 129  * the GPIO is constant and refers to some always-present controller,
 130  * giving direct access to chip registers and tight bitbanging loops.
 131  */
 132 extern int __gpio_get_value(unsigned gpio);
 133 extern void __gpio_set_value(unsigned gpio, int value);
 134
 135 extern int __gpio_cansleep(unsigned gpio);
 136
 137 extern int __gpio_to_irq(unsigned gpio);
 138
 139 #ifdef CONFIG_GPIO_SYSFS
 140
 141 /*
 142  * A sysfs interface can be exported by individual drivers if they want,
 143  * but more typically is configured entirely from userspace.
 144  */
 145 extern int gpio_export(unsigned gpio, bool direction_may_change);
 146 extern int gpio_export_link(struct device *dev, const char *name,
 147                         unsigned gpio);
 148 extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
 149 extern void gpio_unexport(unsigned gpio);
 150
 151 #endif  /* CONFIG_GPIO_SYSFS */
 152
 153 #else   /* !CONFIG_HAVE_GPIO_LIB */
 154
 155 static inline int gpio_is_valid(int number)
 156 {
 157         /* only non-negative numbers are valid */
 158         return number >= 0;
 159 }
 160
 161 /* platforms that don't directly support access to GPIOs through I2C, SPI,
 162  * or other blocking infrastructure can use these wrappers.
 163  */
 164
 165 static inline int gpio_cansleep(unsigned gpio)
 166 {
 167         return 0;
 168 }
 169
 170 static inline int gpio_get_value_cansleep(unsigned gpio)
 171 {
 172         might_sleep();
 173         return gpio_get_value(gpio);
 174 }
 175
 176 static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 177 {
 178         might_sleep();
 179         gpio_set_value(gpio, value);
 180 }
 181
 182 #endif /* !CONFIG_HAVE_GPIO_LIB */
 183
 184 #ifndef CONFIG_GPIO_SYSFS
 185
 186 struct device;
 187
 188 /* sysfs support is only available with gpiolib, where it's optional */
 189
 190 static inline int gpio_export(unsigned gpio, bool direction_may_change)
 191 {
 192         return -ENOSYS;
 193 }
 194
 195 static inline int gpio_export_link(struct device *dev, const char *name,
 196                                 unsigned gpio)
 197 {
 198         return -ENOSYS;
 199 }
 200
 201 static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
 202 {
 203         return -ENOSYS;
 204 }
 205
 206 static inline void gpio_unexport(unsigned gpio)
 207 {
 208 }
 209 #endif  /* CONFIG_GPIO_SYSFS */
 210
 211 #endif /* _ASM_GENERIC_GPIO_H */