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  * @direction_input: configures signal "offset" as input, or returns error
  39  * @get: returns value for signal "offset"; for output signals this
  40  *      returns either the value actually sensed, or zero
  41  * @direction_output: configures signal "offset" as output, or returns error
  42  * @set: assigns output value for signal "offset"
  43  * @dbg_show: optional routine to show contents in debugfs; default code
  44  *      will be used when this is omitted, but custom code can show extra
  45  *      state (such as pullup/pulldown configuration).
  46  * @base: identifies the first GPIO number handled by this chip; or, if
  47  *      negative during registration, requests dynamic ID allocation.
  48  * @ngpio: the number of GPIOs handled by this controller; the last GPIO
  49  *      handled is (base + ngpio - 1).
  50  * @can_sleep: flag must be set iff get()/set() methods sleep, as they
  51  *      must while accessing GPIO expander chips over I2C or SPI
  52  *
  53  * A gpio_chip can help platforms abstract various sources of GPIOs so
  54  * they can all be accessed through a common programing interface.
  55  * Example sources would be SOC controllers, FPGAs, multifunction
  56  * chips, dedicated GPIO expanders, and so on.
  57  *
  58  * Each chip controls a number of signals, identified in method calls
  59  * by "offset" values in the range 0..(@ngpio - 1).  When those signals
  60  * are referenced through calls like gpio_get_value(gpio), the offset
  61  * is calculated by subtracting @base from the gpio number.
  62  */
  63 struct gpio_chip {
  64         char                    *label;
  65         struct device           *dev;
  66         struct module           *owner;
  67
  68         int                     (*direction_input)(struct gpio_chip *chip,
  69                                                 unsigned offset);
  70         int                     (*get)(struct gpio_chip *chip,
  71                                                 unsigned offset);
  72         int                     (*direction_output)(struct gpio_chip *chip,
  73                                                 unsigned offset, int value);
  74         void                    (*set)(struct gpio_chip *chip,
  75                                                 unsigned offset, int value);
  76         void                    (*dbg_show)(struct seq_file *s,
  77                                                 struct gpio_chip *chip);
  78         int                     base;
  79         u16                     ngpio;
  80         unsigned                can_sleep:1;
  81         unsigned                exported:1;
  82 };
  83
  84 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
  85                         unsigned offset);
  86 extern int __must_check gpiochip_reserve(int start, int ngpio);
  87
  88 /* add/remove chips */
  89 extern int gpiochip_add(struct gpio_chip *chip);
  90 extern int __must_check gpiochip_remove(struct gpio_chip *chip);
  91
  92
  93 /* Always use the library code for GPIO management calls,
  94  * or when sleeping may be involved.
  95  */
  96 extern int gpio_request(unsigned gpio, const char *label);
  97 extern void gpio_free(unsigned gpio);
  98
  99 extern int gpio_direction_input(unsigned gpio);
 100 extern int gpio_direction_output(unsigned gpio, int value);
 101
 102 extern int gpio_get_value_cansleep(unsigned gpio);
 103 extern void gpio_set_value_cansleep(unsigned gpio, int value);
 104
 105
 106 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
 107  * the GPIO is constant and refers to some always-present controller,
 108  * giving direct access to chip registers and tight bitbanging loops.
 109  */
 110 extern int __gpio_get_value(unsigned gpio);
 111 extern void __gpio_set_value(unsigned gpio, int value);
 112
 113 extern int __gpio_cansleep(unsigned gpio);
 114
 115
 116 #ifdef CONFIG_GPIO_SYSFS
 117
 118 /*
 119  * A sysfs interface can be exported by individual drivers if they want,
 120  * but more typically is configured entirely from userspace.
 121  */
 122 extern int gpio_export(unsigned gpio, bool direction_may_change);
 123 extern void gpio_unexport(unsigned gpio);
 124
 125 #endif  /* CONFIG_GPIO_SYSFS */
 126
 127 #else   /* !CONFIG_HAVE_GPIO_LIB */
 128
 129 static inline int gpio_is_valid(int number)
 130 {
 131         /* only non-negative numbers are valid */
 132         return number >= 0;
 133 }
 134
 135 /* platforms that don't directly support access to GPIOs through I2C, SPI,
 136  * or other blocking infrastructure can use these wrappers.
 137  */
 138
 139 static inline int gpio_cansleep(unsigned gpio)
 140 {
 141         return 0;
 142 }
 143
 144 static inline int gpio_get_value_cansleep(unsigned gpio)
 145 {
 146         might_sleep();
 147         return gpio_get_value(gpio);
 148 }
 149
 150 static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 151 {
 152         might_sleep();
 153         gpio_set_value(gpio, value);
 154 }
 155
 156 #endif /* !CONFIG_HAVE_GPIO_LIB */
 157
 158 #ifndef CONFIG_GPIO_SYSFS
 159
 160 /* sysfs support is only available with gpiolib, where it's optional */
 161
 162 static inline int gpio_export(unsigned gpio, bool direction_may_change)
 163 {
 164         return -ENOSYS;
 165 }
 166
 167 static inline void gpio_unexport(unsigned gpio)
 168 {
 169 }
 170 #endif  /* CONFIG_GPIO_SYSFS */
 171
 172 #endif /* _ASM_GENERIC_GPIO_H */