efm32: energy management unit headers and example

include/libopencm3/efm32/tinygecko/emu.h

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+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 chrysn <chrysn@fsfe.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file
+ * @see EFM32TG_EMU
+ */
+
+/** Definitions for the EMU subsystem (Energy Management Unit).
+ *
+ * This corresponds to the description in d0034_efm32tg_reference_manual.pdf
+ * section 10.
+ *
+ * @defgroup EFM32TG_EMU EFM32 Tiny Gecko EMU
+ * @{
+ */
+
+#ifndef LIBOPENCM3_EFM32_TINYGECKO_EMU_H
+#define LIBOPENCM3_EFM32_TINYGECKO_EMU_H
+
+#include <libopencm3/cm3/common.h>
+#include <libopencm3/efm32/memorymap.h>
+
+/** Register definitions and register value definitions for the EMU subsystem
+ *
+ * @defgroup EFM32TG_EMU_regsandvals EFM32 Tiny Gecko EMU registers and values
+ * @{
+ */
+
+/** These definitions reflect d0034_efm32tg_reference_manual.pdf section 10.4
+ *
+ * @defgroup EFM32TG_EMU_registers EFM32 Tiny Gecko EMU registers
+ * @{
+ */
+
+#define EMU_CTRL		MMIO32(EMU_BASE + 0x000) /**< @see EFM32TG_EMU_CTRL_bits */
+#define EMU_LOCK		MMIO32(EMU_BASE + 0x008) /**< @see EFM32TG_EMU_LOCK_values */
+#define EMU_AUXCTRL		MMIO32(EMU_BASE + 0x024) /**< @see EFM32TG_EMU_AUXCTRL_bits */
+
+/** @} */
+
+/** Bit states for the EMU_CTRL register
+ *
+ * See d0034_efm32tg_reference_manual.pdf section 10.5.1 for definitions, and
+ * 10.3.2 for details (especially on why EM4CTRL_TWO and _THREE are defined).
+ *
+ * @defgroup EFM32TG_EMU_CTRL_bits EFM32 Tiny Gecko EMU CTRL bits
+ * @{
+ */
+
+#define EMU_CTRL_EM4CTRL_TWO		(2<<2)
+#define EMU_CTRL_EM4CTRL_THREE		(3<<2)
+#define EMU_CTRL_EM2BLOCK		(1<<1) /**< When this bit is set, no mode lower than EM1 will be entered */
+#define EMU_CTRL_EMVREG			(1<<0) /**< When this bit is set, the voltage regulator will stay on in modes lower than EM1 */
+
+/** @} */
+
+/** Values for the EMU_LOCK register
+ *
+ * See d0034_efm32tg_reference_manual.pdf section 10.5.2. There seems not to be
+ * another mention of it.
+ *
+ * @defgroup EFM32TG_EMU_LOCK_values EFM32 Tiny Gecko EMU LOCK values
+ * @{
+ */
+
+#define EMU_LOCK_IS_UNLOCKED		0 /**< When the LOCK register reads as this value, it is open */
+#define EMU_LOCK_IS_LOCKED		1 /**< When the LOCK register reads as this value, it is locked */
+#define EMU_LOCK_SET_LOCKED		0 /**< Write this to the LOCK register to lock the EMU */
+#define EMU_LOCK_SET_UNLOCKED		0xade8 /**< Write this to the LOCK register to unlock the EMU */
+
+/** @} */
+
+/** Bit states for the EMU_AUXCTRL register
+ *
+ * See d0034_efm32tg_reference_manual.pdf section 10.5.3 for definition, and
+ * 9.5.3 for details.
+ *
+ * @defgroup EFM32TG_EMU_AUXCTRL_bits EFM32 Tiny Gecko EMU AUXCTRL bits
+ * @{
+ */
+
+#define EMU_AUXCTRL_HRCCLR		(1<<0)
+
+/** @} */
+
+/** @} */
+
+/** EMU convenience functions
+ *
+ * These functions can be used to send the chip to low energy modes.
+ *
+ * @todo Implement other sleep modes than EM1. Implement WFI vs WFE waits.
+ *
+ * @defgroup EFM32TG_EMU_convenience EFM32 Tiny Gecko EMU convenience functions
+ * @{
+ */
+
+/** Put the system into EM1 low energy mode. */
+static void emu_sleep_em1(void)
+{
+	/* FIXME: set SLEEPDEEP to 0 */
+	__asm__("wfi");
+}
+
+/** @} */
+
+/** @} */
+
+#endif