staging: omap-thermal: add documentation for register access functions

#include "omap-bandgap.h"

/**

 * omap_bandgap_readl() - simple read helper function

 * @bg_ptr: pointer to omap_bandgap structure

 * @reg: desired register (offset) to be read

 *

 * Helper function to read bandgap registers. It uses the io remapped area.

 * Returns the register value.

 */

static u32 omap_bandgap_readl(struct omap_bandgap *bg_ptr, u32 reg)

{

	return readl(bg_ptr->base + reg);

}

/**

 * omap_bandgap_writel() - simple write helper function

 * @bg_ptr: pointer to omap_bandgap structure

 * @val: desired register value to be written

 * @reg: desired register (offset) to be written

 *

 * Helper function to write bandgap registers. It uses the io remapped area.

 */

static void omap_bandgap_writel(struct omap_bandgap *bg_ptr, u32 val, u32 reg)

{

	writel(val, bg_ptr->base + reg);

}

/* update bits, value will be shifted */

/**

 * DOC: macro to update bits.

 *

 * RMW_BITS() - used to read, modify and update bandgap bitfields.

 *            The value passed will be shifted.

 */

#define RMW_BITS(bg_ptr, id, reg, mask, val)			\

do {								\

	struct temp_sensor_registers *t;			\