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#include <linux/of.h>
  8
  9#ifdef CONFIG_GPIOLIB
 10
 11#include <linux/compiler.h>
 12
 13/* Platforms may implement their GPIO interface with library code,
 14 * at a small performance cost for non-inlined operations and some
 15 * extra memory (for code and for per-GPIO table entries).
 16 *
 17 * While the GPIO programming interface defines valid GPIO numbers
 18 * to be in the range 0..MAX_INT, this library restricts them to the
 19 * smaller range 0..ARCH_NR_GPIOS-1.
 20 *
 21 * ARCH_NR_GPIOS is somewhat arbitrary; it usually reflects the sum of
 22 * builtin/SoC GPIOs plus a number of GPIOs on expanders; the latter is
 23 * actually an estimate of a board-specific value.
 24 */
 25
 26#ifndef ARCH_NR_GPIOS
 27#define ARCH_NR_GPIOS		256
 28#endif
 29
 30/*
 31 * "valid" GPIO numbers are nonnegative and may be passed to
 32 * setup routines like gpio_request().  only some valid numbers
 33 * can successfully be requested and used.
 34 *
 35 * Invalid GPIO numbers are useful for indicating no-such-GPIO in
 36 * platform data and other tables.
 37 */
 38
 39static inline bool gpio_is_valid(int number)
 40{
 41	return number >= 0 && number < ARCH_NR_GPIOS;
 42}
 43
 44struct device;
 45struct gpio;
 46struct seq_file;
 47struct module;
 48struct device_node;
 49
 50/**
 51 * struct gpio_chip - abstract a GPIO controller
 52 * @label: for diagnostics
 53 * @dev: optional device providing the GPIOs
 54 * @owner: helps prevent removal of modules exporting active GPIOs
 55 * @request: optional hook for chip-specific activation, such as
 56 *	enabling module power and clock; may sleep
 57 * @free: optional hook for chip-specific deactivation, such as
 58 *	disabling module power and clock; may sleep
 59 * @direction_input: configures signal "offset" as input, or returns error
 60 * @get: returns value for signal "offset"; for output signals this
 61 *	returns either the value actually sensed, or zero
 62 * @direction_output: configures signal "offset" as output, or returns error
 63 * @set: assigns output value for signal "offset"
 64 * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
 65 *	implementation may not sleep
 66 * @dbg_show: optional routine to show contents in debugfs; default code
 67 *	will be used when this is omitted, but custom code can show extra
 68 *	state (such as pullup/pulldown configuration).
 69 * @base: identifies the first GPIO number handled by this chip; or, if
 70 *	negative during registration, requests dynamic ID allocation.
 71 * @ngpio: the number of GPIOs handled by this controller; the last GPIO
 72 *	handled is (base + ngpio - 1).
 73 * @can_sleep: flag must be set iff get()/set() methods sleep, as they
 74 *	must while accessing GPIO expander chips over I2C or SPI
 75 * @names: if set, must be an array of strings to use as alternative
 76 *      names for the GPIOs in this chip. Any entry in the array
 77 *      may be NULL if there is no alias for the GPIO, however the
 78 *      array must be @ngpio entries long.  A name can include a single printk
 79 *      format specifier for an unsigned int.  It is substituted by the actual
 80 *      number of the gpio.
 81 *
 82 * A gpio_chip can help platforms abstract various sources of GPIOs so
 83 * they can all be accessed through a common programing interface.
 84 * Example sources would be SOC controllers, FPGAs, multifunction
 85 * chips, dedicated GPIO expanders, and so on.
 86 *
 87 * Each chip controls a number of signals, identified in method calls
 88 * by "offset" values in the range 0..(@ngpio - 1).  When those signals
 89 * are referenced through calls like gpio_get_value(gpio), the offset
 90 * is calculated by subtracting @base from the gpio number.
 91 */
 92struct gpio_chip {
 93	const char		*label;
 94	struct device		*dev;
 95	struct module		*owner;
 96
 97	int			(*request)(struct gpio_chip *chip,
 98						unsigned offset);
 99	void			(*free)(struct gpio_chip *chip,
100						unsigned offset);
101
102	int			(*direction_input)(struct gpio_chip *chip,
103						unsigned offset);
104	int			(*get)(struct gpio_chip *chip,
105						unsigned offset);
106	int			(*direction_output)(struct gpio_chip *chip,
107						unsigned offset, int value);
108	int			(*set_debounce)(struct gpio_chip *chip,
109						unsigned offset, unsigned debounce);
110
111	void			(*set)(struct gpio_chip *chip,
112						unsigned offset, int value);
113
114	int			(*to_irq)(struct gpio_chip *chip,
115						unsigned offset);
116
117	void			(*dbg_show)(struct seq_file *s,
118						struct gpio_chip *chip);
119	int			base;
120	u16			ngpio;
121	const char		*const *names;
122	unsigned		can_sleep:1;
123	unsigned		exported:1;
124
125#if defined(CONFIG_OF_GPIO)
126	/*
127	 * If CONFIG_OF is enabled, then all GPIO controllers described in the
128	 * device tree automatically may have an OF translation
129	 */
130	struct device_node *of_node;
131	int of_gpio_n_cells;
132	int (*of_xlate)(struct gpio_chip *gc,
133		        const struct of_phandle_args *gpiospec, u32 *flags);
134#endif
135};
136
137extern const char *gpiochip_is_requested(struct gpio_chip *chip,
138			unsigned offset);
139extern struct gpio_chip *gpio_to_chip(unsigned gpio);
140extern int __must_check gpiochip_reserve(int start, int ngpio);
141
142/* add/remove chips */
143extern int gpiochip_add(struct gpio_chip *chip);
144extern int __must_check gpiochip_remove(struct gpio_chip *chip);
145extern struct gpio_chip *gpiochip_find(void *data,
146					int (*match)(struct gpio_chip *chip,
147						     void *data));
148
149
150/* Always use the library code for GPIO management calls,
151 * or when sleeping may be involved.
152 */
153extern int gpio_request(unsigned gpio, const char *label);
154extern void gpio_free(unsigned gpio);
155
156extern int gpio_direction_input(unsigned gpio);
157extern int gpio_direction_output(unsigned gpio, int value);
158
159extern int gpio_set_debounce(unsigned gpio, unsigned debounce);
160
161extern int gpio_get_value_cansleep(unsigned gpio);
162extern void gpio_set_value_cansleep(unsigned gpio, int value);
163
164
165/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
166 * the GPIO is constant and refers to some always-present controller,
167 * giving direct access to chip registers and tight bitbanging loops.
168 */
169extern int __gpio_get_value(unsigned gpio);
170extern void __gpio_set_value(unsigned gpio, int value);
171
172extern int __gpio_cansleep(unsigned gpio);
173
174extern int __gpio_to_irq(unsigned gpio);
175
176extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
177extern int gpio_request_array(const struct gpio *array, size_t num);
178extern void gpio_free_array(const struct gpio *array, size_t num);
179
180/* bindings for managed devices that want to request gpios */
181int devm_gpio_request(struct device *dev, unsigned gpio, const char *label);
182int devm_gpio_request_one(struct device *dev, unsigned gpio,
183			  unsigned long flags, const char *label);
184void devm_gpio_free(struct device *dev, unsigned int gpio);
185
186#ifdef CONFIG_GPIO_SYSFS
187
188/*
189 * A sysfs interface can be exported by individual drivers if they want,
190 * but more typically is configured entirely from userspace.
191 */
192extern int gpio_export(unsigned gpio, bool direction_may_change);
193extern int gpio_export_link(struct device *dev, const char *name,
194			unsigned gpio);
195extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
196extern void gpio_unexport(unsigned gpio);
197
198#endif	/* CONFIG_GPIO_SYSFS */
199
200#else	/* !CONFIG_GPIOLIB */
201
202static inline bool gpio_is_valid(int number)
203{
204	/* only non-negative numbers are valid */
205	return number >= 0;
206}
207
208/* platforms that don't directly support access to GPIOs through I2C, SPI,
209 * or other blocking infrastructure can use these wrappers.
210 */
211
212static inline int gpio_cansleep(unsigned gpio)
213{
214	return 0;
215}
216
217static inline int gpio_get_value_cansleep(unsigned gpio)
218{
219	might_sleep();
220	return __gpio_get_value(gpio);
221}
222
223static inline void gpio_set_value_cansleep(unsigned gpio, int value)
224{
225	might_sleep();
226	__gpio_set_value(gpio, value);
227}
228
229#endif /* !CONFIG_GPIOLIB */
230
231#ifndef CONFIG_GPIO_SYSFS
232
233struct device;
234
235/* sysfs support is only available with gpiolib, where it's optional */
236
237static inline int gpio_export(unsigned gpio, bool direction_may_change)
238{
239	return -ENOSYS;
240}
241
242static inline int gpio_export_link(struct device *dev, const char *name,
243				unsigned gpio)
244{
245	return -ENOSYS;
246}
247
248static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
249{
250	return -ENOSYS;
251}
252
253static inline void gpio_unexport(unsigned gpio)
254{
255}
256#endif	/* CONFIG_GPIO_SYSFS */
257
258#endif /* _ASM_GENERIC_GPIO_H */