cpu/lpc2387: implement periph/pm

Enable IDLE and Deep Powerdown mode.

IDLE is pretty straightforward - insteady of busy waiting, the CPU will
enter an idle state from which it will resume on any event.

Deep Power Down shuts off the entite system except for the battery backup
power domain.
That means the CPU will reset on resume and can be woken by e.g. RTC.

SLEEP and POWERDOWN disable the PLL and the PLL and Flash respectively.
This requires some proper wake-up handling.

Since this turned out to be a major time sink and those modes are never
currently never used in RIOT outside of tests, I left this as an exercise
for a future reader.

cpu/arm7_common/include/arm7_common.h

@@ -72,9 +72,10 @@ extern "C" {
 #define BORD        (BIT4)
 #define PM2         (BIT7)
 
-#define PM_IDLE         (PM0)
-#define PM_SLEEP        (PM2|PM0)
-#define PM_POWERDOWN    (PM1)
+#define PM_IDLE             (PM0)
+#define PM_SLEEP            (PM2|PM0)
+#define PM_POWERDOWN        (PM1)
+#define PM_DEEP_POWERDOWN   (PM2|PM1)
 /** @} */
 
 /**

cpu/lpc2387/Makefile.include

@@ -1,3 +1,4 @@
 include $(RIOTCPU)/arm7_common/Makefile.include
 
 USEMODULE += arm7_common periph bitfield newlib
+USEMODULE += pm_layered

cpu/lpc2387/include/periph_cpu.h

@@ -32,6 +32,13 @@ extern "C" {
  */
 #define __IO volatile
 
+/**
+ * @name    Power mode configuration
+ * @{
+ */
+#define PM_NUM_MODES        (4)
+/** @} */
+
 /**
  * @brief Fast GPIO register definition struct
  */

cpu/lpc2387/periph/pm.c

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2019 Beuth Hochschule für Technik 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 details.
+ */
+
+/**
+ * @ingroup     cpu_lpc2387
+ * @ingroup     drivers_periph_pm
+ * @{
+ *
+ * @file
+ * @brief       Implementation of the kernels power management interface
+ *
+ * @note        Handling of wake-up from POWERDOWN & SLEEP is not implemented
+ *              yet, so those states are disabled.
+ *
+ * @author      Benjamin Valentin <benpicco@beuth-hochschule.de>
+ *
+ * @}
+ */
+
+#include "periph/pm.h"
+
+#define ENABLE_DEBUG (0)
+#include "debug.h"
+
+void pm_set(unsigned mode)
+{
+    switch (mode) {
+        case 0:
+            /* Everything except battery backup is powered down */
+            DEBUG_PUTS("pm_set(): setting Deep Power Down mode.");
+            PCON |= PM_DEEP_POWERDOWN;
+            break;
+        case 1:
+            /* PLL & Flash are powered down */
+            DEBUG_PUTS("pm_set(): setting Power Down mode.");
+            /* PCON |= PM_POWERDOWN; */
+            PCON |= PM_IDLE; /* fixme */
+            break;
+        case 2:
+            /* PLL is powered down */
+            DEBUG_PUTS("pm_set(): setting Sleep mode.");
+            /* PCON |= PM_SLEEP; */
+            PCON |= PM_IDLE; /* fixme */
+            break;
+        default: /* Falls through */
+        case 3:
+            DEBUG_PUTS("pm_set(): setting Idle mode.");
+            PCON |= PM_IDLE;
+            break;
+    }
+}