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44 lines
1.7 KiB
44 lines
1.7 KiB
#ifndef __LINUX_PCF857X_H |
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#define __LINUX_PCF857X_H |
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/** |
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* struct pcf857x_platform_data - data to set up pcf857x driver |
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* @gpio_base: number of the chip's first GPIO |
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* @n_latch: optional bit-inverse of initial register value; if |
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* you leave this initialized to zero the driver will act |
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* like the chip was just reset |
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* @setup: optional callback issued once the GPIOs are valid |
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* @teardown: optional callback issued before the GPIOs are invalidated |
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* @context: optional parameter passed to setup() and teardown() |
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* |
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* In addition to the I2C_BOARD_INFO() state appropriate to each chip, |
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* the i2c_board_info used with the pcf875x driver must provide its |
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* platform_data (pointer to one of these structures) with at least |
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* the gpio_base value initialized. |
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* |
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* The @setup callback may be used with the kind of board-specific glue |
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* which hands the (now-valid) GPIOs to other drivers, or which puts |
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* devices in their initial states using these GPIOs. |
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* |
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* These GPIO chips are only "quasi-bidirectional"; read the chip specs |
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* to understand the behavior. They don't have separate registers to |
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* record which pins are used for input or output, record which output |
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* values are driven, or provide access to input values. That must be |
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* inferred by reading the chip's value and knowing the last value written |
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* to it. If you leave n_latch initialized to zero, that last written |
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* value is presumed to be all ones (as if the chip were just reset). |
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*/ |
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struct pcf857x_platform_data { |
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unsigned gpio_base; |
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unsigned n_latch; |
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int (*setup)(struct i2c_client *client, |
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int gpio, unsigned ngpio, |
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void *context); |
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int (*teardown)(struct i2c_client *client, |
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int gpio, unsigned ngpio, |
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void *context); |
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void *context; |
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}; |
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#endif /* __LINUX_PCF857X_H */
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