include/asm-generic/gpio.h

   1 #ifndef _ASM_GENERIC_GPIO_H
   2 #define _ASM_GENERIC_GPIO_H
   3
   4 #include <linux/kernel.h>
   5 #include <linux/types.h>
   6 #include <linux/errno.h>
   7
   8 #ifdef CONFIG_GPIOLIB
   9
  10 #include <linux/compiler.h>
  11
  12 /* Platforms may implement their GPIO interface with library code,
  13  * at a small performance cost for non-inlined operations and some
  14  * extra memory (for code and for per-GPIO table entries).
  15  *
  16  * While the GPIO programming interface defines valid GPIO numbers
  17  * to be in the range 0..MAX_INT, this library restricts them to the
  18  * smaller range 0..ARCH_NR_GPIOS-1.
  19  */
  20
  21 #ifndef ARCH_NR_GPIOS
  22 #define ARCH_NR_GPIOS           256
  23 #endif
  24
  25 static inline int gpio_is_valid(int number)
  26 {
  27         /* only some non-negative numbers are valid */
  28         return ((unsigned)number) < ARCH_NR_GPIOS;
  29 }
  30
  31 struct seq_file;
  32 struct module;
  33
  34 /**
  35  * struct gpio_chip - abstract a GPIO controller
  36  * @label: for diagnostics
  37  * @dev: optional device providing the GPIOs
  38  * @owner: helps prevent removal of modules exporting active GPIOs
  39  * @request: optional hook for chip-specific activation, such as
  40  *      enabling module power and clock; may sleep
  41  * @free: optional hook for chip-specific deactivation, such as
  42  *      disabling module power and clock; may sleep
  43  * @direction_input: configures signal "offset" as input, or returns error
  44  * @get: returns value for signal "offset"; for output signals this
  45  *      returns either the value actually sensed, or zero
  46  * @direction_output: configures signal "offset" as output, or returns error
  47  * @set: assigns output value for signal "offset"
  48  * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
  49  *      implementation may not sleep
  50  * @dbg_show: optional routine to show contents in debugfs; default code
  51  *      will be used when this is omitted, but custom code can show extra
  52  *      state (such as pullup/pulldown configuration).
  53  * @base: identifies the first GPIO number handled by this chip; or, if
  54  *      negative during registration, requests dynamic ID allocation.
  55  * @ngpio: the number of GPIOs handled by this controller; the last GPIO
  56  *      handled is (base + ngpio - 1).
  57  * @can_sleep: flag must be set iff get()/set() methods sleep, as they
  58  *      must while accessing GPIO expander chips over I2C or SPI
  59  * @names: if set, must be an array of strings to use as alternative
  60  *      names for the GPIOs in this chip. Any entry in the array
  61  *      may be NULL if there is no alias for the GPIO, however the
  62  *      array must be @ngpio entries long.
  63  *
  64  * A gpio_chip can help platforms abstract various sources of GPIOs so
  65  * they can all be accessed through a common programing interface.
  66  * Example sources would be SOC controllers, FPGAs, multifunction
  67  * chips, dedicated GPIO expanders, and so on.
  68  *
  69  * Each chip controls a number of signals, identified in method calls
  70  * by "offset" values in the range 0..(@ngpio - 1).  When those signals
  71  * are referenced through calls like gpio_get_value(gpio), the offset
  72  * is calculated by subtracting @base from the gpio number.
  73  */
  74 struct gpio_chip {
  75         const char              *label;
  76         struct device           *dev;
  77         struct module           *owner;
  78
  79         int                     (*request)(struct gpio_chip *chip,
  80                                                 unsigned offset);
  81         void                    (*free)(struct gpio_chip *chip,
  82                                                 unsigned offset);
  83
  84         int                     (*direction_input)(struct gpio_chip *chip,
  85                                                 unsigned offset);
  86         int                     (*get)(struct gpio_chip *chip,
  87                                                 unsigned offset);
  88         int                     (*direction_output)(struct gpio_chip *chip,
  89                                                 unsigned offset, int value);
  90         void                    (*set)(struct gpio_chip *chip,
  91                                                 unsigned offset, int value);
  92
  93         int                     (*to_irq)(struct gpio_chip *chip,
  94                                                 unsigned offset);
  95
  96         void                    (*dbg_show)(struct seq_file *s,
  97                                                 struct gpio_chip *chip);
  98         int                     base;
  99         u16                     ngpio;
 100         char                    **names;
 101         unsigned                can_sleep:1;
 102         unsigned                exported:1;
 103 };
 104
 105 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
 106                         unsigned offset);
 107 extern int __must_check gpiochip_reserve(int start, int ngpio);
 108
 109 /* add/remove chips */
 110 extern int gpiochip_add(struct gpio_chip *chip);
 111 extern int __must_check gpiochip_remove(struct gpio_chip *chip);
 112
 113
 114 /* Always use the library code for GPIO management calls,
 115  * or when sleeping may be involved.
 116  */
 117 extern int gpio_request(unsigned gpio, const char *label);
 118 extern void gpio_free(unsigned gpio);
 119
 120 extern int gpio_direction_input(unsigned gpio);
 121 extern int gpio_direction_output(unsigned gpio, int value);
 122
 123 extern int gpio_get_value_cansleep(unsigned gpio);
 124 extern void gpio_set_value_cansleep(unsigned gpio, int value);
 125
 126
 127 /* A platform's <asm/gpio.h> code may want to inline the I/O calls when
 128  * the GPIO is constant and refers to some always-present controller,
 129  * giving direct access to chip registers and tight bitbanging loops.
 130  */
 131 extern int __gpio_get_value(unsigned gpio);
 132 extern void __gpio_set_value(unsigned gpio, int value);
 133
 134 extern int __gpio_cansleep(unsigned gpio);
 135
 136 extern int __gpio_to_irq(unsigned gpio);
 137
 138 #ifdef CONFIG_GPIO_SYSFS
 139
 140 /*
 141  * A sysfs interface can be exported by individual drivers if they want,
 142  * but more typically is configured entirely from userspace.
 143  */
 144 extern int gpio_export(unsigned gpio, bool direction_may_change);
 145 extern int gpio_export_link(struct device *dev, const char *name,
 146                         unsigned gpio);
 147 extern void gpio_unexport(unsigned gpio);
 148
 149 #endif  /* CONFIG_GPIO_SYSFS */
 150
 151 #else   /* !CONFIG_HAVE_GPIO_LIB */
 152
 153 static inline int gpio_is_valid(int number)
 154 {
 155         /* only non-negative numbers are valid */
 156         return number >= 0;
 157 }
 158
 159 /* platforms that don't directly support access to GPIOs through I2C, SPI,
 160  * or other blocking infrastructure can use these wrappers.
 161  */
 162
 163 static inline int gpio_cansleep(unsigned gpio)
 164 {
 165         return 0;
 166 }
 167
 168 static inline int gpio_get_value_cansleep(unsigned gpio)
 169 {
 170         might_sleep();
 171         return gpio_get_value(gpio);
 172 }
 173
 174 static inline void gpio_set_value_cansleep(unsigned gpio, int value)
 175 {
 176         might_sleep();
 177         gpio_set_value(gpio, value);
 178 }
 179
 180 #endif /* !CONFIG_HAVE_GPIO_LIB */
 181
 182 #ifndef CONFIG_GPIO_SYSFS
 183
 184 /* sysfs support is only available with gpiolib, where it's optional */
 185
 186 static inline int gpio_export(unsigned gpio, bool direction_may_change)
 187 {
 188         return -ENOSYS;
 189 }
 190
 191 static inline int gpio_export_link(struct device *dev, const char *name,
 192                                 unsigned gpio)
 193 {
 194         return -ENOSYS;
 195 }
 196
 197 static inline void gpio_unexport(unsigned gpio)
 198 {
 199 }
 200 #endif  /* CONFIG_GPIO_SYSFS */
 201
 202 #endif /* _ASM_GENERIC_GPIO_H */