From cfac198fc8b4d82d6ff434fdd1e1cb574cebb6f7 Mon Sep 17 00:00:00 2001
From: Hauke Petersen <hauke.petersen@fu-berlin.de>
Date: Sat, 13 Feb 2016 13:05:21 +0100
Subject: [PATCH] cpu/stm32f0: added gpio_init_analog()

---
 cpu/stm32f0/include/periph_cpu.h | 7 +++++++
 cpu/stm32f0/periph/gpio.c        | 9 +++++++++
 2 files changed, 16 insertions(+)

diff --git a/cpu/stm32f0/include/periph_cpu.h b/cpu/stm32f0/include/periph_cpu.h
index 3b9d9a8bf2..50e82c637f 100644
--- a/cpu/stm32f0/include/periph_cpu.h
+++ b/cpu/stm32f0/include/periph_cpu.h
@@ -87,6 +87,13 @@ typedef enum {
  */
 void gpio_init_af(gpio_t pin, gpio_af_t af);
 
+/**
+ * @brief   Configure the given pin to be used as ADC input
+ *
+ * @param[in] pin       pin to configure
+ */
+void gpio_init_analog(gpio_t pin);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/cpu/stm32f0/periph/gpio.c b/cpu/stm32f0/periph/gpio.c
index 61b63ba21b..d3b9e7b9bc 100644
--- a/cpu/stm32f0/periph/gpio.c
+++ b/cpu/stm32f0/periph/gpio.c
@@ -140,6 +140,15 @@ void gpio_init_af(gpio_t pin, gpio_af_t af)
     port->AFR[(pin_num > 7) ? 1 : 0] |= (af << ((pin_num & 0x07) * 4));
 }
 
+void gpio_init_analog(gpio_t pin)
+{
+    /* enable clock, needed as this function can be used without calling
+     * gpio_init first */
+    RCC->AHBENR |= (RCC_AHBENR_GPIOAEN << _port_num(pin));
+    /* set to analog mode */
+    _port(pin)->MODER |= (0x3 << (2 * _pin_num(pin)));
+}
+
 void gpio_irq_enable(gpio_t pin)
 {
     EXTI->IMR |= (1 << _pin_num(pin));