From 64f04e4da9e0e2d7abb28324576b682be07c3fe3 Mon Sep 17 00:00:00 2001
From: Koen Zandberg <koen@bergzand.net>
Date: Sat, 7 Mar 2020 17:04:06 +0100
Subject: [PATCH] nrf5x: Add built-in DC/DC converter enable function

The internal DC/DC converter is more efficient compared to the LDO
regulator.  The downside of the DC/DC converter is that it requires an
external inductor to be present on the board. Enabling the DC/DC
converter is guarded with NRF5X_ENABLE_DCDC, this macro must be defined
if the DC/DC converter is to be enabled.
---
 cpu/nrf51/cpu.c                 |  3 +++
 cpu/nrf52/cpu.c                 |  3 +++
 cpu/nrf5x_common/include/nrfx.h | 20 +++++++++++++++++++-
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/cpu/nrf51/cpu.c b/cpu/nrf51/cpu.c
index 28210f9a6d..54b42952d4 100644
--- a/cpu/nrf51/cpu.c
+++ b/cpu/nrf51/cpu.c
@@ -19,6 +19,7 @@
 
 #include "cpu.h"
 #include "nrf_clock.h"
+#include "nrfx.h"
 #include "periph_conf.h"
 #include "periph/init.h"
 #include "stdio_base.h"
@@ -30,6 +31,8 @@ void cpu_init(void)
 {
     /* initialize the Cortex-M core */
     cortexm_init();
+    /* Enable the DC/DC power converter */
+    nrfx_dcdc_init();
     /* setup the HF clock */
     clock_init_hf();
     /* initialize stdio prior to periph_init() to allow use of DEBUG() there */
diff --git a/cpu/nrf52/cpu.c b/cpu/nrf52/cpu.c
index a26554023b..2b0f2a6885 100644
--- a/cpu/nrf52/cpu.c
+++ b/cpu/nrf52/cpu.c
@@ -23,6 +23,7 @@
 #define DONT_OVERRIDE_NVIC
 
 #include "cpu.h"
+#include "nrfx.h"
 #include "nrf_clock.h"
 #include "periph_conf.h"
 #include "periph/init.h"
@@ -61,6 +62,8 @@ void cpu_init(void)
         NRF_CLOCK->EVENTS_DONE = 0;
         NRF_CLOCK->EVENTS_CTTO = 0;
     }
+    /* Enable the DC/DC power converter */
+    nrfx_dcdc_init();
 
     /* initialize hf clock */
     clock_init_hf();
diff --git a/cpu/nrf5x_common/include/nrfx.h b/cpu/nrf5x_common/include/nrfx.h
index 67ee9eed2b..9a3a2519db 100644
--- a/cpu/nrf5x_common/include/nrfx.h
+++ b/cpu/nrf5x_common/include/nrfx.h
@@ -1,5 +1,7 @@
 /*
  * Copyright (C) 2018 Freie Universität Berlin
+ * Copyright (C) 2020 Inria
+ * Copyright (C) 2020 Koen Zandberg <koen@bergzand.net>
  *
  * 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
@@ -14,18 +16,34 @@
  * @brief           nrfx compatibility layer
  *
  * @author          Hauke Petersen <hauke.petersen@fu-berlin.de>
+ * @author          Koen Zandberg <koen@bergzand.net>
  */
 
 #ifndef NRFX_H
 #define NRFX_H
 
 #include "cpu_conf.h"
+#include "periph_conf.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/* nothing else to do here */
+/**
+ * @brief Enable the internal DC/DC power converter for the NRF5x MCU.
+ *
+ * The internal DC/DC converter is more efficient compared to the LDO regulator.
+ * The downside of the DC/DC converter is that it requires an external inductor
+ * to be present on the board. Enabling the DC/DC converter is guarded with
+ * NRF5X_ENABLE_DCDC, this macro must be defined if the DC/DC converter is to be
+ * enabled.
+ */
+static inline void nrfx_dcdc_init(void)
+{
+#ifdef NRF5X_ENABLE_DCDC
+    NRF_POWER->DCDCEN = 1;
+#endif
+}
 
 #ifdef __cplusplus
 }