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