David Brownell | 15fae37 | 2008-02-04 22:28:24 -0800 | [diff] [blame] | 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 the |
| 16 | * chip "type" ("pcf8574", "pcf8574a", "pcf8575", "pcf8575c") and its |
| 17 | * platform_data (pointer to one of these structures) with at least |
| 18 | * the gpio_base value initialized. |
| 19 | * |
| 20 | * The @setup callback may be used with the kind of board-specific glue |
| 21 | * which hands the (now-valid) GPIOs to other drivers, or which puts |
| 22 | * devices in their initial states using these GPIOs. |
| 23 | * |
| 24 | * These GPIO chips are only "quasi-bidirectional"; read the chip specs |
| 25 | * to understand the behavior. They don't have separate registers to |
| 26 | * record which pins are used for input or output, record which output |
| 27 | * values are driven, or provide access to input values. That must be |
| 28 | * inferred by reading the chip's value and knowing the last value written |
| 29 | * to it. If you leave n_latch initialized to zero, that last written |
| 30 | * value is presumed to be all ones (as if the chip were just reset). |
| 31 | */ |
| 32 | struct pcf857x_platform_data { |
| 33 | unsigned gpio_base; |
| 34 | unsigned n_latch; |
| 35 | |
| 36 | int (*setup)(struct i2c_client *client, |
| 37 | int gpio, unsigned ngpio, |
| 38 | void *context); |
| 39 | int (*teardown)(struct i2c_client *client, |
| 40 | int gpio, unsigned ngpio, |
| 41 | void *context); |
| 42 | void *context; |
| 43 | }; |
| 44 | |
| 45 | #endif /* __LINUX_PCF857X_H */ |