/** CMU convenience functions
 *
 * These functions assist in clock switching, and are intended to be safer to
 * use than direct fiddling with registers. They try to be suitable for typical
 * applications, and will invest some bytes of code in order to minimize power
 * consumption.
 *
 * @todo Work on this module is stalled until I can figure out if there is a
 * way to have a cmu_shutdown_unused function at all.
 *
 * @defgroup EFM32TG_CMU_convenience CMU convenience functions
 * @{
 */

/** Disable all oscillators not currently in use.
 *
 * The implementation follows d0034_efm32tg_reference_manual.pdf figure 11.1.
 * The clock out pin configurations are not depicted there, but described in
 * section 11.3.4.
 *
 * @todo This function is ignorant of ongoing calibrations.
 *
 * @todo This doesn't work at all: Fields like HFCLKSEL are write-only.
 * */
static void cmu_shutdown_unused(void)
{
	/* Is HFXO needed? */
	if (!(
	    (CMU_CMD & CMU_CMD_HFCLKSEL_MASK) == CMU_CMD_HFCLKSEL_HFXO ||
	    (
	        (CMU_CTRL & CMU_CTRL_CLKOUTSEL1_MASK) == CMU_CTRL_CLKOUTSEL1_HFXOQ &&
		(CMU_ROUTE & CMU_ROUTE_CLKOUT1PEN)
	    ) || (
	        (CMU_CTRL & CMU_CTRL_CLKOUTSEL0_MASK) == CMU_CTRL_CLKOUTSEL0_HFXO &&
		(CMU_ROUTE & CMU_ROUTE_CLKOUT0PEN)
	    )))
		CMU_OSCENCMD = CMU_OSCENCMD_HFXODIS;

	/* Is HFRCO neede? */
	if (!(
	    (CMU_CMD & CMU_CMD_HFCLKSEL_MASK) == CMU_CMD_HFCLKSEL_HFRCO ||
	    (
	        (CMU_CTRL & CMU_CTRL_CLKOUTSEL1_MASK) == CMU_CTRL_CLKOUTSEL1_HFRCOQ &&
		(CMU_ROUTE & CMU_ROUTE_CLKOUT1PEN)
	    ) || (
	        (CMU_CTRL & CMU_CTRL_CLKOUTSEL0_MASK) == CMU_CTRL_CLKOUTSEL0_HFRCO &&
		(CMU_ROUTE & CMU_ROUTE_CLKOUT0PEN)
	    )))
	{}
//		CMU_OSCENCMD = CMU_OSCENCMD_HFRCODIS;
}

/** Switch HFCLK to LFRC. This call is not only blocking, but even freezes
 * everything depending on HFCLK until LFRC is stable. The procedure is
 * sketched in d0034_efm32tg_reference_manual.pdf figure 11.2. */
static void cmu_hfclk_switch_blocking(void)
{
	CMU_OSCENCMD = CMU_OSCENCMD_LFRCOEN;
	CMU_CMD = CMU_CMD_HFCLKSEL_LFRCO;
	CMU_OSCENCMD = CMU_OSCENCMD_HFRCODIS;
}

/** @} */