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 */