include/asm-generic/gpio.h

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