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1 #ifndef __LINUX_PCF857X_H
2 #define __LINUX_PCF857X_H
3 
4 /**
5  * struct pcf857x_platform_data - data to set up pcf857x driver
6  * @gpio_base: number of the chip's first GPIO
7  * @n_latch: optional bit-inverse of initial register value; if
8  *	you leave this initialized to zero the driver will act
9  *	like the chip was just reset
10  * @setup: optional callback issued once the GPIOs are valid
11  * @teardown: optional callback issued before the GPIOs are invalidated
12  * @context: optional parameter passed to setup() and teardown()
13  *
14  * In addition to the I2C_BOARD_INFO() state appropriate to each chip,
15  * the i2c_board_info used with the pcf875x driver must provide its
16  * platform_data (pointer to one of these structures) with at least
17  * the gpio_base value initialized.
18  *
19  * The @setup callback may be used with the kind of board-specific glue
20  * which hands the (now-valid) GPIOs to other drivers, or which puts
21  * devices in their initial states using these GPIOs.
22  *
23  * These GPIO chips are only "quasi-bidirectional"; read the chip specs
24  * to understand the behavior.  They don't have separate registers to
25  * record which pins are used for input or output, record which output
26  * values are driven, or provide access to input values.  That must be
27  * inferred by reading the chip's value and knowing the last value written
28  * to it.  If you leave n_latch initialized to zero, that last written
29  * value is presumed to be all ones (as if the chip were just reset).
30  */
31 struct pcf857x_platform_data {
32 	unsigned	gpio_base;
33 	unsigned	n_latch;
34 
35 	int		(*setup)(struct i2c_client *client,
36 					int gpio, unsigned ngpio,
37 					void *context);
38 	int		(*teardown)(struct i2c_client *client,
39 					int gpio, unsigned ngpio,
40 					void *context);
41 	void		*context;
42 };
43 
44 #endif /* __LINUX_PCF857X_H */
45