cpu: stm32f1: add periph/pm support

cpu/stm32f1/Makefile.features

+FEATURE_PROVIDED += periph_pm

cpu/stm32f1/include/periph_cpu.h

@@ -123,6 +123,8 @@ typedef struct {
     uint8_t chan;           /**< DAC device used for this line */
 } dac_conf_t;
 
+#define PM_NUM_MODES    (2U)
+
 #ifdef __cplusplus
 }
 #endif

cpu/stm32f1/periph/pm.c

+/*
+ * Copyright (C) 2016 Kaspar Schleiser <kaspar@schleiser.de>
+ *               2015 Engineering-Spirit
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     cpu_stm32f1
+ * @{
+ *
+ * @file
+ * @brief       Implementation of the kernels power management interface
+ *
+ * @author      Nick v. IJzendoorn <nijzndoorn@engineering-spirit.nl>
+ * @author      Kaspar Schleiser <kaspar@schleiser.de>
+ *
+ * @}
+ */
+
+#include "periph/pm.h"
+
+#define ENABLE_DEBUG (1)
+#include "debug.h"
+
+void pm_set(unsigned mode)
+{
+    switch (mode) {
+        case 0:                  /* STM Sleep mode */
+            /* Reset SLEEPDEEP bit of system control block */
+            SCB->SCR &= ~(SCB_SCR_SLEEPDEEP_Msk);
+            break;
+        case 1:                 /* STM Stop mode */
+            /* Clear PDDS and LPDS bits to enter stop mode on */
+            /* deepsleep with voltage regulator on */
+            PWR->CR &= ~(PWR_CR_PDDS | PWR_CR_LPDS);
+            /* Set SLEEPDEEP bit of system control block */
+            SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;
+            break;
+        default:
+            DEBUG("pm: invalid power mode selected.\n");
+    }
+
+    /* Executes a device DSB (Data Synchronization Barrier) */
+    __DSB();
+    /* Enter standby mode */
+    __WFI();
+}
+
+void pm_off(void)
+{
+    /* Set PDDS to enter standby mode on deepsleep and clear flags */
+    PWR->CR |= (PWR_CR_PDDS | PWR_CR_CWUF | PWR_CR_CSBF);
+    /* Enable WKUP pin to use for wakeup from standby mode */
+    PWR->CSR |= PWR_CSR_EWUP;
+    /* Set SLEEPDEEP bit of system control block */
+    SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;
+
+    __DSB();
+    __WFI();
+}