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 * ARCH_NR_GPIOS is somewhat arbitrary; it usually reflects the sum of
 21 * builtin/SoC GPIOs plus a number of GPIOs on expanders; the latter is
 22 * actually an estimate of a board-specific value.
 23 */
 24
 25#ifndef ARCH_NR_GPIOS
 26#define ARCH_NR_GPIOS		256
 27#endif
 28
 29/*
 30 * "valid" GPIO numbers are nonnegative and may be passed to
 31 * setup routines like gpio_request().  only some valid numbers
 32 * can successfully be requested and used.
 33 *
 34 * Invalid GPIO numbers are useful for indicating no-such-GPIO in
 35 * platform data and other tables.
 36 */
 37
 38static inline bool gpio_is_valid(int number)
 39{
 40	return number >= 0 && number < ARCH_NR_GPIOS;
 41}
 42
 43struct device;
 44struct seq_file;
 45struct module;
 46struct device_node;
 47
 48/**
 49 * struct gpio_chip - abstract a GPIO controller
 50 * @label: for diagnostics
 51 * @dev: optional device providing the GPIOs
 52 * @owner: helps prevent removal of modules exporting active GPIOs
 53 * @request: optional hook for chip-specific activation, such as
 54 *	enabling module power and clock; may sleep
 55 * @free: optional hook for chip-specific deactivation, such as
 56 *	disabling module power and clock; may sleep
 57 * @direction_input: configures signal "offset" as input, or returns error
 58 * @get: returns value for signal "offset"; for output signals this
 59 *	returns either the value actually sensed, or zero
 60 * @direction_output: configures signal "offset" as output, or returns error
 61 * @set: assigns output value for signal "offset"
 62 * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
 63 *	implementation may not sleep
 64 * @dbg_show: optional routine to show contents in debugfs; default code
 65 *	will be used when this is omitted, but custom code can show extra
 66 *	state (such as pullup/pulldown configuration).
 67 * @base: identifies the first GPIO number handled by this chip; or, if
 68 *	negative during registration, requests dynamic ID allocation.
 69 * @ngpio: the number of GPIOs handled by this controller; the last GPIO
 70 *	handled is (base + ngpio - 1).
 71 * @can_sleep: flag must be set iff get()/set() methods sleep, as they
 72 *	must while accessing GPIO expander chips over I2C or SPI
 73 * @names: if set, must be an array of strings to use as alternative
 74 *      names for the GPIOs in this chip. Any entry in the array
 75 *      may be NULL if there is no alias for the GPIO, however the
 76 *      array must be @ngpio entries long.  A name can include a single printk
 77 *      format specifier for an unsigned int.  It is substituted by the actual
 78 *      number of the gpio.
 79 *
 80 * A gpio_chip can help platforms abstract various sources of GPIOs so
 81 * they can all be accessed through a common programing interface.
 82 * Example sources would be SOC controllers, FPGAs, multifunction
 83 * chips, dedicated GPIO expanders, and so on.
 84 *
 85 * Each chip controls a number of signals, identified in method calls
 86 * by "offset" values in the range 0..(@ngpio - 1).  When those signals
 87 * are referenced through calls like gpio_get_value(gpio), the offset
 88 * is calculated by subtracting @base from the gpio number.
 89 */
 90struct gpio_chip {
 91	const char		*label;
 92	struct device		*dev;
 93	struct module		*owner;
 94
 95	int			(*request)(struct gpio_chip *chip,
 96						unsigned offset);
 97	void			(*free)(struct gpio_chip *chip,
 98						unsigned offset);
 99
100	int			(*direction_input)(struct gpio_chip *chip,
101						unsigned offset);
102	int			(*get)(struct gpio_chip *chip,
103						unsigned offset);
104	int			(*direction_output)(struct gpio_chip *chip,
105						unsigned offset, int value);
106	int			(*set_debounce)(struct gpio_chip *chip,
107						unsigned offset, unsigned debounce);
108
109	void			(*set)(struct gpio_chip *chip,
110						unsigned offset, int value);
111
112	int			(*to_irq)(struct gpio_chip *chip,
113						unsigned offset);
114
115	void			(*dbg_show)(struct seq_file *s,
116						struct gpio_chip *chip);
117	int			base;
118	u16			ngpio;
119	const char		*const *names;
120	unsigned		can_sleep:1;
121	unsigned		exported:1;
122
123#if defined(CONFIG_OF_GPIO)
124	/*
125	 * If CONFIG_OF is enabled, then all GPIO controllers described in the
126	 * device tree automatically may have an OF translation
127	 */
128	struct device_node *of_node;
129	int of_gpio_n_cells;
130	int (*of_xlate)(struct gpio_chip *gc, struct device_node *np,
131		        const void *gpio_spec, u32 *flags);
132#endif
133};
134
135extern const char *gpiochip_is_requested(struct gpio_chip *chip,
136			unsigned offset);
137extern int __must_check gpiochip_reserve(int start, int ngpio);
138
139/* add/remove chips */
140extern int gpiochip_add(struct gpio_chip *chip);
141extern int __must_check gpiochip_remove(struct gpio_chip *chip);
142extern struct gpio_chip *gpiochip_find(void *data,
143					int (*match)(struct gpio_chip *chip,
144						     void *data));
145
146
147/* Always use the library code for GPIO management calls,
148 * or when sleeping may be involved.
149 */
150extern int gpio_request(unsigned gpio, const char *label);
151extern void gpio_free(unsigned gpio);
152
153extern int gpio_direction_input(unsigned gpio);
154extern int gpio_direction_output(unsigned gpio, int value);
155
156extern int gpio_set_debounce(unsigned gpio, unsigned debounce);
157
158extern int gpio_get_value_cansleep(unsigned gpio);
159extern void gpio_set_value_cansleep(unsigned gpio, int value);
160
161
162/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
163 * the GPIO is constant and refers to some always-present controller,
164 * giving direct access to chip registers and tight bitbanging loops.
165 */
166extern int __gpio_get_value(unsigned gpio);
167extern void __gpio_set_value(unsigned gpio, int value);
168
169extern int __gpio_cansleep(unsigned gpio);
170
171extern int __gpio_to_irq(unsigned gpio);
172
173/**
174 * struct gpio - a structure describing a GPIO with configuration
175 * @gpio:	the GPIO number
176 * @flags:	GPIO configuration as specified by GPIOF_*
177 * @label:	a literal description string of this GPIO
178 */
179struct gpio {
180	unsigned	gpio;
181	unsigned long	flags;
182	const char	*label;
183};
184
185extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
186extern int gpio_request_array(const struct gpio *array, size_t num);
187extern void gpio_free_array(const struct gpio *array, size_t num);
188
189#ifdef CONFIG_GPIO_SYSFS
190
191/*
192 * A sysfs interface can be exported by individual drivers if they want,
193 * but more typically is configured entirely from userspace.
194 */
195extern int gpio_export(unsigned gpio, bool direction_may_change);
196extern int gpio_export_link(struct device *dev, const char *name,
197			unsigned gpio);
198extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
199extern void gpio_unexport(unsigned gpio);
200
201#endif	/* CONFIG_GPIO_SYSFS */
202
203#else	/* !CONFIG_GPIOLIB */
204
205static inline bool gpio_is_valid(int number)
206{
207	/* only non-negative numbers are valid */
208	return number >= 0;
209}
210
211/* platforms that don't directly support access to GPIOs through I2C, SPI,
212 * or other blocking infrastructure can use these wrappers.
213 */
214
215static inline int gpio_cansleep(unsigned gpio)
216{
217	return 0;
218}
219
220static inline int gpio_get_value_cansleep(unsigned gpio)
221{
222	might_sleep();
223	return gpio_get_value(gpio);
224}
225
226static inline void gpio_set_value_cansleep(unsigned gpio, int value)
227{
228	might_sleep();
229	gpio_set_value(gpio, value);
230}
231
232#endif /* !CONFIG_GPIOLIB */
233
234#ifndef CONFIG_GPIO_SYSFS
235
236struct device;
237
238/* sysfs support is only available with gpiolib, where it's optional */
239
240static inline int gpio_export(unsigned gpio, bool direction_may_change)
241{
242	return -ENOSYS;
243}
244
245static inline int gpio_export_link(struct device *dev, const char *name,
246				unsigned gpio)
247{
248	return -ENOSYS;
249}
250
251static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
252{
253	return -ENOSYS;
254}
255
256static inline void gpio_unexport(unsigned gpio)
257{
258}
259#endif	/* CONFIG_GPIO_SYSFS */
260
261#endif /* _ASM_GENERIC_GPIO_H */