include/asm-generic/gpio.h

   1 #ifndef _ASM_GENERIC_GPIO_H
   2 #define _ASM_GENERIC_GPIO_H
   3
   4 #include <linux/types.h>
   5 #include <linux/errno.h>
   6
   7 #ifdef CONFIG_GPIOLIB
   8
   9 #include <linux/compiler.h>
  10
  11 /* Platforms may implement their GPIO interface with library code,
  12  * at a small performance cost for non-inlined operations and some
  13  * extra memory (for code and for per-GPIO table entries).
  14  *
  15  * While the GPIO programming interface defines valid GPIO numbers
  16  * to be in the range 0..MAX_INT, this library restricts them to the
  17  * smaller range 0..ARCH_NR_GPIOS-1.
  18  */
  19
  20 #ifndef ARCH_NR_GPIOS
  21 #define ARCH_NR_GPIOS           256
  22 #endif
  23
  24 static inline int gpio_is_valid(int number)
  25 {
  26         /* only some non-negative numbers are valid */
  27         return ((unsigned)number) < ARCH_NR_GPIOS;
  28 }
  29
  30 struct seq_file;
  31 struct module;
  32
  33 /**
  34  * struct gpio_chip - abstract a GPIO controller
  35  * @label: for diagnostics
  36  * @dev: optional device providing the GPIOs
  37  * @owner: helps prevent removal of modules exporting active GPIOs
  38  * @request: optional hook for chip-specific activation, such as
  39  *      enabling module power and clock; may sleep
  40  * @free: optional hook for chip-specific deactivation, such as
  41  *      disabling module power and clock; may sleep
  42  * @direction_input: configures signal "offset" as input, or returns error
  43  * @get: returns value for signal "offset"; for output signals this
  44  *      returns either the value actually sensed, or zero
  45  * @direction_output: configures signal "offset" as output, or returns error
  46  * @set: assigns output value for signal "offset"
  47  * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
  48  *      implementation may not sleep
  49  * @dbg_show: optional routine to show contents in debugfs; default code
  50  *      will be used when this is omitted, but custom code can show extra
  51  *      state (such as pullup/pulldown configuration).
  52  * @base: identifies the first GPIO number handled by this chip; or, if
  53  *      negative during registration, requests dynamic ID allocation.
  54  * @ngpio: the number of GPIOs handled by this controller; the last GPIO
  55  *      handled is (base + ngpio - 1).
  56  * @can_sleep: flag must be set iff get()/set() methods sleep, as they
  57  *      must while accessing GPIO expander chips over I2C or SPI
  58  *
  59  * A gpio_chip can help platforms abstract various sources of GPIOs so
  60  * they can all be accessed through a common programing interface.
  61  * Example sources would be SOC controllers, FPGAs, multifunction
  62  * chips, dedicated GPIO expanders, and so on.
  63  *
  64  * Each chip controls a number of signals, identified in method calls
  65  * by "offset" values in the range 0..(@ngpio - 1).  When those signals
  66  * are referenced through calls like gpio_get_value(gpio), the offset
  67  * is calculated by subtracting @base from the gpio number.
  68  */
  69 struct gpio_chip {
  70         const char              *label;
  71         struct device           *dev;
  72         struct module           *owner;
  73
  74         int                     (*request)(struct gpio_chip *chip,
  75                                                 unsigned offset);
  76         void                    (*free)(struct gpio_chip *chip,
  77                                                 unsigned offset);
  78
  79         int                     (*direction_input)(struct gpio_chip *chip,
  80                                                 unsigned offset);
  81         int                     (*get)(struct gpio_chip *chip,
  82                                                 unsigned offset);
  83         int                     (*direction_output)(struct gpio_chip *chip,
  84                                                 unsigned offset, int value);
  85         void                    (*set)(struct gpio_chip *chip,
  86                                                 unsigned offset, int value);
  87
  88         int                     (*to_irq)(struct gpio_chip *chip,
  89                                                 unsigned offset);
  90
  91         void                    (*dbg_show)(struct seq_file *s,
  92                                                 struct gpio_chip *chip);
  93         int                     base;
  94         u16                     ngpio;
  95         unsigned                can_sleep:1;
  96         unsigned                exported:1;
  97 };
  98
  99 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
 100                         unsigned offset);
 101 extern int __must_check gpiochip_reserve(int start, int ngpio);
 102
 103 /* add/remove chips */
 104 extern int gpiochip_add(struct gpio_chip *chip);
 105 extern int __must_check gpiochip_remove(struct gpio_chip *chip);
 106
 107
 108 /* Always use the library code for GPIO management calls,
 109  * or when sleeping may be involved.
 110  */
 111 extern int gpio_request(unsigned gpio, const char *label);
 112 extern void gpio_free(unsigned gpio);
 113
 114 extern int gpio_direction_input(unsigned gpio);
 115 extern int gpio_direction_output(unsigned gpio, int value);
 116
 117 extern int gpio_get_value_cansleep(unsigned gpio);
 118 extern void gpio_set_value_cansleep(unsigned gpio, int value);
 119
 120
 121 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
 122  * the GPIO is constant and refers to some always-present controller,
 123  * giving direct access to chip registers and tight bitbanging loops.
 124  */
 125 extern int __gpio_get_value(unsigned gpio);
 126 extern void __gpio_set_value(unsigned gpio, int value);
 127
 128 extern int __gpio_cansleep(unsigned gpio);
 129
 130 extern int __gpio_to_irq(unsigned gpio);
 131
 132 #ifdef CONFIG_GPIO_SYSFS
 133
 134 /*
 135  * A sysfs interface can be exported by individual drivers if they want,
 136  * but more typically is configured entirely from userspace.
 137  */
 138 extern int gpio_export(unsigned gpio, bool direction_may_change);
 139 extern void gpio_unexport(unsigned gpio);
 140
 141 #endif  /* CONFIG_GPIO_SYSFS */
 142
 143 #else   /* !CONFIG_HAVE_GPIO_LIB */
 144
 145 static inline int gpio_is_valid(int number)
 146 {
 147         /* only non-negative numbers are valid */
 148         return number >= 0;
 149 }
 150
 151 /* platforms that don't directly support access to GPIOs through I2C, SPI,
 152  * or other blocking infrastructure can use these wrappers.
 153  */
 154
 155 static inline int gpio_cansleep(unsigned gpio)
 156 {
 157         return 0;
 158 }
 159
 160 static inline int gpio_get_value_cansleep(unsigned gpio)
 161 {
 162         might_sleep();
 163         return gpio_get_value(gpio);
 164 }
 165
 166 static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 167 {
 168         might_sleep();
 169         gpio_set_value(gpio, value);
 170 }
 171
 172 #endif /* !CONFIG_HAVE_GPIO_LIB */
 173
 174 #ifndef CONFIG_GPIO_SYSFS
 175
 176 /* sysfs support is only available with gpiolib, where it's optional */
 177
 178 static inline int gpio_export(unsigned gpio, bool direction_may_change)
 179 {
 180         return -ENOSYS;
 181 }
 182
 183 static inline void gpio_unexport(unsigned gpio)
 184 {
 185 }
 186 #endif  /* CONFIG_GPIO_SYSFS */
 187
 188 #endif /* _ASM_GENERIC_GPIO_H */