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  * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
  44  *      implementation may not sleep
  45  * @dbg_show: optional routine to show contents in debugfs; default code
  46  *      will be used when this is omitted, but custom code can show extra
  47  *      state (such as pullup/pulldown configuration).
  48  * @base: identifies the first GPIO number handled by this chip; or, if
  49  *      negative during registration, requests dynamic ID allocation.
  50  * @ngpio: the number of GPIOs handled by this controller; the last GPIO
  51  *      handled is (base + ngpio - 1).
  52  * @can_sleep: flag must be set iff get()/set() methods sleep, as they
  53  *      must while accessing GPIO expander chips over I2C or SPI
  54  *
  55  * A gpio_chip can help platforms abstract various sources of GPIOs so
  56  * they can all be accessed through a common programing interface.
  57  * Example sources would be SOC controllers, FPGAs, multifunction
  58  * chips, dedicated GPIO expanders, and so on.
  59  *
  60  * Each chip controls a number of signals, identified in method calls
  61  * by "offset" values in the range 0..(@ngpio - 1).  When those signals
  62  * are referenced through calls like gpio_get_value(gpio), the offset
  63  * is calculated by subtracting @base from the gpio number.
  64  */
  65 struct gpio_chip {
  66         const char              *label;
  67         struct device           *dev;
  68         struct module           *owner;
  69
  70         int                     (*direction_input)(struct gpio_chip *chip,
  71                                                 unsigned offset);
  72         int                     (*get)(struct gpio_chip *chip,
  73                                                 unsigned offset);
  74         int                     (*direction_output)(struct gpio_chip *chip,
  75                                                 unsigned offset, int value);
  76         void                    (*set)(struct gpio_chip *chip,
  77                                                 unsigned offset, int value);
  78
  79         int                     (*to_irq)(struct gpio_chip *chip,
  80                                                 unsigned offset);
  81
  82         void                    (*dbg_show)(struct seq_file *s,
  83                                                 struct gpio_chip *chip);
  84         int                     base;
  85         u16                     ngpio;
  86         unsigned                can_sleep:1;
  87         unsigned                exported:1;
  88 };
  89
  90 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
  91                         unsigned offset);
  92 extern int __must_check gpiochip_reserve(int start, int ngpio);
  93
  94 /* add/remove chips */
  95 extern int gpiochip_add(struct gpio_chip *chip);
  96 extern int __must_check gpiochip_remove(struct gpio_chip *chip);
  97
  98
  99 /* Always use the library code for GPIO management calls,
 100  * or when sleeping may be involved.
 101  */
 102 extern int gpio_request(unsigned gpio, const char *label);
 103 extern void gpio_free(unsigned gpio);
 104
 105 extern int gpio_direction_input(unsigned gpio);
 106 extern int gpio_direction_output(unsigned gpio, int value);
 107
 108 extern int gpio_get_value_cansleep(unsigned gpio);
 109 extern void gpio_set_value_cansleep(unsigned gpio, int value);
 110
 111
 112 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
 113  * the GPIO is constant and refers to some always-present controller,
 114  * giving direct access to chip registers and tight bitbanging loops.
 115  */
 116 extern int __gpio_get_value(unsigned gpio);
 117 extern void __gpio_set_value(unsigned gpio, int value);
 118
 119 extern int __gpio_cansleep(unsigned gpio);
 120
 121 extern int __gpio_to_irq(unsigned gpio);
 122
 123 #ifdef CONFIG_GPIO_SYSFS
 124
 125 /*
 126  * A sysfs interface can be exported by individual drivers if they want,
 127  * but more typically is configured entirely from userspace.
 128  */
 129 extern int gpio_export(unsigned gpio, bool direction_may_change);
 130 extern void gpio_unexport(unsigned gpio);
 131
 132 #endif  /* CONFIG_GPIO_SYSFS */
 133
 134 #else   /* !CONFIG_HAVE_GPIO_LIB */
 135
 136 static inline int gpio_is_valid(int number)
 137 {
 138         /* only non-negative numbers are valid */
 139         return number >= 0;
 140 }
 141
 142 /* platforms that don't directly support access to GPIOs through I2C, SPI,
 143  * or other blocking infrastructure can use these wrappers.
 144  */
 145
 146 static inline int gpio_cansleep(unsigned gpio)
 147 {
 148         return 0;
 149 }
 150
 151 static inline int gpio_get_value_cansleep(unsigned gpio)
 152 {
 153         might_sleep();
 154         return gpio_get_value(gpio);
 155 }
 156
 157 static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 158 {
 159         might_sleep();
 160         gpio_set_value(gpio, value);
 161 }
 162
 163 #endif /* !CONFIG_HAVE_GPIO_LIB */
 164
 165 #ifndef CONFIG_GPIO_SYSFS
 166
 167 /* sysfs support is only available with gpiolib, where it's optional */
 168
 169 static inline int gpio_export(unsigned gpio, bool direction_may_change)
 170 {
 171         return -ENOSYS;
 172 }
 173
 174 static inline void gpio_unexport(unsigned gpio)
 175 {
 176 }
 177 #endif  /* CONFIG_GPIO_SYSFS */
 178
 179 #endif /* _ASM_GENERIC_GPIO_H */