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  * @request: optional hook for chip-specific activation, such as
  39  *      enabling module power and clock; may sleep
  40  * @free: optional hook for chip-specific deactivation, such as
  41  *      disabling module power and clock; may sleep
  42  * @direction_input: configures signal "offset" as input, or returns error
  43  * @get: returns value for signal "offset"; for output signals this
  44  *      returns either the value actually sensed, or zero
  45  * @direction_output: configures signal "offset" as output, or returns error
  46  * @set: assigns output value for signal "offset"
  47  * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
  48  *      implementation may not sleep
  49  * @dbg_show: optional routine to show contents in debugfs; default code
  50  *      will be used when this is omitted, but custom code can show extra
  51  *      state (such as pullup/pulldown configuration).
  52  * @base: identifies the first GPIO number handled by this chip; or, if
  53  *      negative during registration, requests dynamic ID allocation.
  54  * @ngpio: the number of GPIOs handled by this controller; the last GPIO
  55  *      handled is (base + ngpio - 1).
  56  * @can_sleep: flag must be set iff get()/set() methods sleep, as they
  57  *      must while accessing GPIO expander chips over I2C or SPI
  58  * @names: if set, must be an array of strings to use as alternative
  59  *      names for the GPIOs in this chip. Any entry in the array
  60  *      may be NULL if there is no alias for the GPIO, however the
  61  *      array must be @ngpio entries long.
  62  *
  63  * A gpio_chip can help platforms abstract various sources of GPIOs so
  64  * they can all be accessed through a common programing interface.
  65  * Example sources would be SOC controllers, FPGAs, multifunction
  66  * chips, dedicated GPIO expanders, and so on.
  67  *
  68  * Each chip controls a number of signals, identified in method calls
  69  * by "offset" values in the range 0..(@ngpio - 1).  When those signals
  70  * are referenced through calls like gpio_get_value(gpio), the offset
  71  * is calculated by subtracting @base from the gpio number.
  72  */
  73 struct gpio_chip {
  74         const char              *label;
  75         struct device           *dev;
  76         struct module           *owner;
  77
  78         int                     (*request)(struct gpio_chip *chip,
  79                                                 unsigned offset);
  80         void                    (*free)(struct gpio_chip *chip,
  81                                                 unsigned offset);
  82
  83         int                     (*direction_input)(struct gpio_chip *chip,
  84                                                 unsigned offset);
  85         int                     (*get)(struct gpio_chip *chip,
  86                                                 unsigned offset);
  87         int                     (*direction_output)(struct gpio_chip *chip,
  88                                                 unsigned offset, int value);
  89         void                    (*set)(struct gpio_chip *chip,
  90                                                 unsigned offset, int value);
  91
  92         int                     (*to_irq)(struct gpio_chip *chip,
  93                                                 unsigned offset);
  94
  95         void                    (*dbg_show)(struct seq_file *s,
  96                                                 struct gpio_chip *chip);
  97         int                     base;
  98         u16                     ngpio;
  99         char                    **names;
 100         unsigned                can_sleep:1;
 101         unsigned                exported:1;
 102 };
 103
 104 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
 105                         unsigned offset);
 106 extern int __must_check gpiochip_reserve(int start, int ngpio);
 107
 108 /* add/remove chips */
 109 extern int gpiochip_add(struct gpio_chip *chip);
 110 extern int __must_check gpiochip_remove(struct gpio_chip *chip);
 111
 112
 113 /* Always use the library code for GPIO management calls,
 114  * or when sleeping may be involved.
 115  */
 116 extern int gpio_request(unsigned gpio, const char *label);
 117 extern void gpio_free(unsigned gpio);
 118
 119 extern int gpio_direction_input(unsigned gpio);
 120 extern int gpio_direction_output(unsigned gpio, int value);
 121
 122 extern int gpio_get_value_cansleep(unsigned gpio);
 123 extern void gpio_set_value_cansleep(unsigned gpio, int value);
 124
 125
 126 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
 127  * the GPIO is constant and refers to some always-present controller,
 128  * giving direct access to chip registers and tight bitbanging loops.
 129  */
 130 extern int __gpio_get_value(unsigned gpio);
 131 extern void __gpio_set_value(unsigned gpio, int value);
 132
 133 extern int __gpio_cansleep(unsigned gpio);
 134
 135 extern int __gpio_to_irq(unsigned gpio);
 136
 137 #ifdef CONFIG_GPIO_SYSFS
 138
 139 /*
 140  * A sysfs interface can be exported by individual drivers if they want,
 141  * but more typically is configured entirely from userspace.
 142  */
 143 extern int gpio_export(unsigned gpio, bool direction_may_change);
 144 extern void gpio_unexport(unsigned gpio);
 145
 146 #endif  /* CONFIG_GPIO_SYSFS */
 147
 148 #else   /* !CONFIG_HAVE_GPIO_LIB */
 149
 150 static inline int gpio_is_valid(int number)
 151 {
 152         /* only non-negative numbers are valid */
 153         return number >= 0;
 154 }
 155
 156 /* platforms that don't directly support access to GPIOs through I2C, SPI,
 157  * or other blocking infrastructure can use these wrappers.
 158  */
 159
 160 static inline int gpio_cansleep(unsigned gpio)
 161 {
 162         return 0;
 163 }
 164
 165 static inline int gpio_get_value_cansleep(unsigned gpio)
 166 {
 167         might_sleep();
 168         return gpio_get_value(gpio);
 169 }
 170
 171 static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 172 {
 173         might_sleep();
 174         gpio_set_value(gpio, value);
 175 }
 176
 177 #endif /* !CONFIG_HAVE_GPIO_LIB */
 178
 179 #ifndef CONFIG_GPIO_SYSFS
 180
 181 /* sysfs support is only available with gpiolib, where it's optional */
 182
 183 static inline int gpio_export(unsigned gpio, bool direction_may_change)
 184 {
 185         return -ENOSYS;
 186 }
 187
 188 static inline void gpio_unexport(unsigned gpio)
 189 {
 190 }
 191 #endif  /* CONFIG_GPIO_SYSFS */
 192
 193 #endif /* _ASM_GENERIC_GPIO_H */