cpu/stm32f4: Add low power mode implementation

cpu/stm32f4/lpm_arch.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014 Freie Universität Berlin
+ * Copyright (C) 2015 Freie Universität Berlin
  *
  * 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
@@ -13,41 +13,86 @@
  * @file
  * @brief       Implementation of the kernels power management interface
  *
- * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
+ * @author      Fabian Nack <nack@inf.fu-berlin.de>
  *
  * @}
  */
 
+#include "cpu.h"
 #include "arch/lpm_arch.h"
 
+static enum lpm_mode current_mode = LPM_UNKNOWN;
+
 void lpm_arch_init(void)
 {
-    /* TODO */
+    current_mode = LPM_ON;
 }
 
 enum lpm_mode lpm_arch_set(enum lpm_mode target)
 {
-    /* TODO */
-    return 0;
+    enum lpm_mode last_mode = current_mode;
+
+    switch (target) {
+        case LPM_ON:                    /* STM Run mode */
+            current_mode = LPM_ON;
+            break;
+        case LPM_IDLE:                  /* STM Sleep mode */
+            current_mode = LPM_IDLE;
+            /* Reset SLEEPDEEP bit of system control block */
+            SCB->SCR &= ~(SCB_SCR_SLEEPDEEP_Msk);
+            /* Enter sleep mode */
+            __WFI();
+            break;
+        case LPM_SLEEP:                 /* STM Stop mode */
+            current_mode = LPM_SLEEP;
+            /* 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;
+            /* Enter stop mode */
+            __WFI();
+            break;
+        case LPM_POWERDOWN:             /* STM Standby mode */
+            /* Fall-through */
+        case LPM_OFF:                   /* STM Standby mode */
+            current_mode = LPM_POWERDOWN;
+            /* 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;
+#if defined ( __CC_ARM   )
+            /* Ensure that store operations are completed */
+            __force_stores();
+#endif
+            /* Enter standby mode */
+            __WFI();
+            break;
+        default:
+            break;
+    }
+
+    return last_mode;
 }
 
 enum lpm_mode lpm_arch_get(void)
 {
-    /* TODO */
-    return 0;
+    return current_mode;
 }
 
 void lpm_arch_awake(void)
 {
-    /* TODO */
+    if (current_mode == LPM_SLEEP) {
+        /* After stop mode, the clock system needs to be reconfigured */
+        cpu_init();
+    }
+    current_mode = LPM_ON;
 }
 
-void lpm_arch_begin_awake(void)
-{
-    /* TODO */
-}
+/** Not provided */
+inline void lpm_arch_begin_awake(void) { }
 
-void lpm_arch_end_awake(void)
-{
-    /* TODO */
-}
+/** Not provided */
+inline void lpm_arch_end_awake(void) { }