Add initial support for STM32F4

lib/stm32/f4/pwr.c

@@ -0,0 +1,28 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2011 Stephen Caudle <scaudle@doceme.com>
+ *
+ * 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/>.
+ */
+
+#include <libopencm3/stm32/f4/pwr.h>
+
+void pwr_set_vos_scale(vos_scale_t scale)
+{
+	if (scale == SCALE1)
+		PWR_CR |= PWR_CR_VOS;
+	else if (scale == SCALE2)
+		PWR_CR &= PWR_CR_VOS;
+}