Add initial flash memory register support.

Thanks Thomas Otto <tommi@viadmin.org> for the patch!

lib/flash.c

@@ -0,0 +1,50 @@
+/*
+ * This file is part of the libopenstm32 project.
+ *
+ * Copyright (C) 2010 Thomas Otto <tommi@viadmin.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/>.
+ */
+
+#include <libopenstm32.h>
+
+void flash_prefetch_buffer_enable(void)
+{
+	FLASH_ACR |= PRFTBE;
+}
+
+void flash_prefetch_buffer_disable(void)
+{
+	FLASH_ACR &= ~PRFTBE;
+}
+
+void flash_halfcycle_enable(void)
+{
+	FLASH_ACR |= HLFCYA;
+}
+
+void flash_halfcycle_disable(void)
+{
+	FLASH_ACR &= ~HLFCYA;
+}
+
+void flash_set_ws(u32 ws)
+{
+	u32 reg32;
+
+	reg32 = FLASH_ACR;
+	reg32 &= ~((1 << 0) | (1 << 1) | (1 << 2));
+	reg32 |= ws;
+	FLASH_ACR = reg32;
+}