include/asm-generic/gpio.h

   1 #ifndef _ASM_GENERIC_GPIO_H
   2 #define _ASM_GENERIC_GPIO_H
   3
   4 #ifdef CONFIG_HAVE_GPIO_LIB
   5
   6 /* Platforms may implement their GPIO interface with library code,
   7  * at a small performance cost for non-inlined operations and some
   8  * extra memory (for code and for per-GPIO table entries).
   9  *
  10  * While the GPIO programming interface defines valid GPIO numbers
  11  * to be in the range 0..MAX_INT, this library restricts them to the
  12  * smaller range 0..ARCH_NR_GPIOS.
  13  */
  14
  15 #ifndef ARCH_NR_GPIOS
  16 #define ARCH_NR_GPIOS           256
  17 #endif
  18
  19 struct seq_file;
  20
  21 /**
  22  * struct gpio_chip - abstract a GPIO controller
  23  * @label: for diagnostics
  24  * @direction_input: configures signal "offset" as input, or returns error
  25  * @get: returns value for signal "offset"; for output signals this
  26  *      returns either the value actually sensed, or zero
  27  * @direction_output: configures signal "offset" as output, or returns error
  28  * @set: assigns output value for signal "offset"
  29  * @dbg_show: optional routine to show contents in debugfs; default code
  30  *      will be used when this is omitted, but custom code can show extra
  31  *      state (such as pullup/pulldown configuration).
  32  * @base: identifies the first GPIO number handled by this chip; or, if
  33  *      negative during registration, requests dynamic ID allocation.
  34  * @ngpio: the number of GPIOs handled by this controller; the last GPIO
  35  *      handled is (base + ngpio - 1).
  36  * @can_sleep: flag must be set iff get()/set() methods sleep, as they
  37  *      must while accessing GPIO expander chips over I2C or SPI
  38  *
  39  * A gpio_chip can help platforms abstract various sources of GPIOs so
  40  * they can all be accessed through a common programing interface.
  41  * Example sources would be SOC controllers, FPGAs, multifunction
  42  * chips, dedicated GPIO expanders, and so on.
  43  *
  44  * Each chip controls a number of signals, identified in method calls
  45  * by "offset" values in the range 0..(@ngpio - 1).  When those signals
  46  * are referenced through calls like gpio_get_value(gpio), the offset
  47  * is calculated by subtracting @base from the gpio number.
  48  */
  49 struct gpio_chip {
  50         char                    *label;
  51
  52         int                     (*direction_input)(struct gpio_chip *chip,
  53                                                 unsigned offset);
  54         int                     (*get)(struct gpio_chip *chip,
  55                                                 unsigned offset);
  56         int                     (*direction_output)(struct gpio_chip *chip,
  57                                                 unsigned offset, int value);
  58         void                    (*set)(struct gpio_chip *chip,
  59                                                 unsigned offset, int value);
  60         void                    (*dbg_show)(struct seq_file *s,
  61                                                 struct gpio_chip *chip);
  62         int                     base;
  63         u16                     ngpio;
  64         unsigned                can_sleep:1;
  65 };
  66
  67 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
  68                         unsigned offset);
  69
  70 /* add/remove chips */
  71 extern int gpiochip_add(struct gpio_chip *chip);
  72 extern int __must_check gpiochip_remove(struct gpio_chip *chip);
  73
  74
  75 /* Always use the library code for GPIO management calls,
  76  * or when sleeping may be involved.
  77  */
  78 extern int gpio_request(unsigned gpio, const char *label);
  79 extern void gpio_free(unsigned gpio);
  80
  81 extern int gpio_direction_input(unsigned gpio);
  82 extern int gpio_direction_output(unsigned gpio, int value);
  83
  84 extern int gpio_get_value_cansleep(unsigned gpio);
  85 extern void gpio_set_value_cansleep(unsigned gpio, int value);
  86
  87
  88 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
  89  * the GPIO is constant and refers to some always-present controller,
  90  * giving direct access to chip registers and tight bitbanging loops.
  91  */
  92 extern int __gpio_get_value(unsigned gpio);
  93 extern void __gpio_set_value(unsigned gpio, int value);
  94
  95 extern int __gpio_cansleep(unsigned gpio);
  96
  97
  98 #else
  99
 100 /* platforms that don't directly support access to GPIOs through I2C, SPI,
 101  * or other blocking infrastructure can use these wrappers.
 102  */
 103
 104 static inline int gpio_cansleep(unsigned gpio)
 105 {
 106         return 0;
 107 }
 108
 109 static inline int gpio_get_value_cansleep(unsigned gpio)
 110 {
 111         might_sleep();
 112         return gpio_get_value(gpio);
 113 }
 114
 115 static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 116 {
 117         might_sleep();
 118         gpio_set_value(gpio, value);
 119 }
 120
 121 #endif
 122
 123 #endif /* _ASM_GENERIC_GPIO_H */