1 files changed, 85 insertions, 0 deletions
diff --git a/libmaple/bkp.c b/libmaple/bkp.c
new file mode 100644
index 0000000..5b0ad4a
--- /dev/null
+++ b/libmaple/bkp.c
@@ -0,0 +1,85 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 LeafLabs, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+#include "libmaple.h"
+#include "bkp.h"
+#include "pwr.h"
+#include "rcc.h"
+#include "util.h"
+
+/* Data register memory layout is not contiguous.  It's split up from
+   1--NR_LOW_DRS, beginning at BKP_LOW_OFFSET, through
+   (NR_LOW_DRS+1)--NR_DRS, beginning at BKP_HIGH_OFFSET. */
+#define NR_LOW_DRS 10
+#define BKP_LOW_OFFSET  0x4    /* start offset for data registers 1--10 */
+#define BKP_HIGH_OFFSET 0x40   /* start offset for data registers 11--42 */
+
+inline volatile uint16* reg_addr(uint8 reg) {
+    if (1 <= reg) {
+        if (reg <= NR_LOW_DRS) {
+            return (volatile uint16*)(BKP_BASE + BKP_LOW_OFFSET +
+                                      (reg - 1) * 4);
+        } else if (reg <= NR_BKP_REGS) {
+            return (volatile uint16*)(BKP_BASE + BKP_HIGH_OFFSET +
+                                      (reg - NR_LOW_DRS - 1) * 4);
+        }
+    }
+    return 0;
+}
+
+void bkp_init(void) {
+    /* Set PWREN (28) and BKPEN (27) bits */
+    __set_bits(RCC_APB1ENR, BIT(28) | BIT(27));
+}
+
+void bkp_disable(void) {
+    __clear_bits(RCC_APB1ENR, BIT(28) | BIT(27));
+}
+
+void bkp_enable_writes(void) {
+    /* Set the DBP bit in PWR_CR */
+    __write(BITBAND_PERI(PWR_CR, PWR_CR_DBP), 1);
+}
+
+void bkp_disable_writes(void) {
+    __write(BITBAND_PERI(PWR_CR, PWR_CR_DBP), 0);
+}
+
+uint16 bkp_read(uint8 reg) {
+    volatile uint16* addr = reg_addr(reg);
+    if (addr != 0) {
+        return *addr;
+    }
+    ASSERT(0);
+    return 0;
+}
+
+void bkp_write(uint8 reg, uint16 val) {
+    volatile uint16* addr = reg_addr(reg);
+    if (addr != 0) {
+        *addr = val;
+    }
+}