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 static inline int gpio_is_valid(int number)
  20 {
  21         /* only some non-negative numbers are valid */
  22         return ((unsigned)number) < ARCH_NR_GPIOS;
  23 }
  24
  25 struct seq_file;
  26 struct module;
  27
  28 /**
  29  * struct gpio_chip - abstract a GPIO controller
  30  * @label: for diagnostics
  31  * @direction_input: configures signal "offset" as input, or returns error
  32  * @get: returns value for signal "offset"; for output signals this
  33  *      returns either the value actually sensed, or zero
  34  * @direction_output: configures signal "offset" as output, or returns error
  35  * @set: assigns output value for signal "offset"
  36  * @dbg_show: optional routine to show contents in debugfs; default code
  37  *      will be used when this is omitted, but custom code can show extra
  38  *      state (such as pullup/pulldown configuration).
  39  * @base: identifies the first GPIO number handled by this chip; or, if
  40  *      negative during registration, requests dynamic ID allocation.
  41  * @ngpio: the number of GPIOs handled by this controller; the last GPIO
  42  *      handled is (base + ngpio - 1).
  43  * @can_sleep: flag must be set iff get()/set() methods sleep, as they
  44  *      must while accessing GPIO expander chips over I2C or SPI
  45  *
  46  * A gpio_chip can help platforms abstract various sources of GPIOs so
  47  * they can all be accessed through a common programing interface.
  48  * Example sources would be SOC controllers, FPGAs, multifunction
  49  * chips, dedicated GPIO expanders, and so on.
  50  *
  51  * Each chip controls a number of signals, identified in method calls
  52  * by "offset" values in the range 0..(@ngpio - 1).  When those signals
  53  * are referenced through calls like gpio_get_value(gpio), the offset
  54  * is calculated by subtracting @base from the gpio number.
  55  */
  56 struct gpio_chip {
  57         char                    *label;
  58         struct module           *owner;
  59
  60         int                     (*direction_input)(struct gpio_chip *chip,
  61                                                 unsigned offset);
  62         int                     (*get)(struct gpio_chip *chip,
  63                                                 unsigned offset);
  64         int                     (*direction_output)(struct gpio_chip *chip,
  65                                                 unsigned offset, int value);
  66         void                    (*set)(struct gpio_chip *chip,
  67                                                 unsigned offset, int value);
  68         void                    (*dbg_show)(struct seq_file *s,
  69                                                 struct gpio_chip *chip);
  70         int                     base;
  71         u16                     ngpio;
  72         unsigned                can_sleep:1;
  73 };
  74
  75 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
  76                         unsigned offset);
  77 extern int __init __must_check gpiochip_reserve(int start, int ngpio);
  78
  79 /* add/remove chips */
  80 extern int gpiochip_add(struct gpio_chip *chip);
  81 extern int __must_check gpiochip_remove(struct gpio_chip *chip);
  82
  83
  84 /* Always use the library code for GPIO management calls,
  85  * or when sleeping may be involved.
  86  */
  87 extern int gpio_request(unsigned gpio, const char *label);
  88 extern void gpio_free(unsigned gpio);
  89
  90 extern int gpio_direction_input(unsigned gpio);
  91 extern int gpio_direction_output(unsigned gpio, int value);
  92
  93 extern int gpio_get_value_cansleep(unsigned gpio);
  94 extern void gpio_set_value_cansleep(unsigned gpio, int value);
  95
  96
  97 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
  98  * the GPIO is constant and refers to some always-present controller,
  99  * giving direct access to chip registers and tight bitbanging loops.
 100  */
 101 extern int __gpio_get_value(unsigned gpio);
 102 extern void __gpio_set_value(unsigned gpio, int value);
 103
 104 extern int __gpio_cansleep(unsigned gpio);
 105
 106
 107 #else
 108
 109 static inline int gpio_is_valid(int number)
 110 {
 111         /* only non-negative numbers are valid */
 112         return number >= 0;
 113 }
 114
 115 /* platforms that don't directly support access to GPIOs through I2C, SPI,
 116  * or other blocking infrastructure can use these wrappers.
 117  */
 118
 119 static inline int gpio_cansleep(unsigned gpio)
 120 {
 121         return 0;
 122 }
 123
 124 static inline int gpio_get_value_cansleep(unsigned gpio)
 125 {
 126         might_sleep();
 127         return gpio_get_value(gpio);
 128 }
 129
 130 static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 131 {
 132         might_sleep();
 133         gpio_set_value(gpio, value);
 134 }
 135
 136 #endif
 137
 138 #endif /* _ASM_GENERIC_GPIO_H */