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/include/linux/i2c/pcf857x.h

https://bitbucket.org/thekraven/iscream_thunderc-2.6.35
C++ Header | 44 lines | 14 code | 3 blank | 27 comment | 0 complexity | 9897f4fc20e561fc51e5f321079651cf MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
 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 */
31struct 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 */