kernel-fxtec-pro1x/include/linux/i2c/pca953x.h

/* platform data for the PCA9539 16-bit I/O expander driver */

struct pca953x_platform_data {
	/* number of the first GPIO */
	unsigned	gpio_base;

	/* initial polarity inversion setting */
	uint16_t	invert;

	void		*context;	/* param to setup/teardown */

	int		(*setup)(struct i2c_client *client,
				unsigned gpio, unsigned ngpio,
				void *context);
	int		(*teardown)(struct i2c_client *client,
				unsigned gpio, unsigned ngpio,
				void *context);
};