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