From 258c882c8cb2baa802f5e9a1722a11a6ba627965 Mon Sep 17 00:00:00 2001
From: Thomas Klaehn <thomas.klaehn@perinet.io>
Date: Fri, 8 Jan 2021 10:44:56 +0100
Subject: [PATCH] Add C++ independent watchdog driver

---
 platform/stm32g0xx/IndependentWatchdog.cc | 41 +++++++++++++++++++++++
 platform/stm32g0xx/IndependentWatchdog.h  | 24 +++++++++++++
 2 files changed, 65 insertions(+)
 create mode 100644 platform/stm32g0xx/IndependentWatchdog.cc
 create mode 100644 platform/stm32g0xx/IndependentWatchdog.h

diff --git a/platform/stm32g0xx/IndependentWatchdog.cc b/platform/stm32g0xx/IndependentWatchdog.cc
new file mode 100644
index 0000000..45e092f
--- /dev/null
+++ b/platform/stm32g0xx/IndependentWatchdog.cc
@@ -0,0 +1,41 @@
+#include "platform/stm32g0xx/IndependentWatchdog.h"
+
+using namespace perinet::platform::stm32g0xx;
+
+IndependentWatchdog::IndependentWatchdog(uint32_t window, uint32_t reload)
+    : window(window)
+    , reload(reload)
+{
+}
+
+void IndependentWatchdog::enable()
+{
+    // Enable IWDG. LSI is turned on automatically
+    IWDG->KR = IWDG_KEY_ENABLE;
+
+    // Enable write access to IWDG_PR, IWDG_RLR and IWDG_WINR registers by writing 0x5555 in KR
+    IWDG->KR = IWDG_KEY_WRITE_ACCESS_ENABLE;
+
+    // Write to IWDG registers the Prescaler & Reload values to work with
+    IWDG->PR = IWDG_PRESCALER_4;
+    IWDG->RLR = this->reload;
+
+    // If window parameter is different than current value, modify window register
+    if (IWDG->WINR != this->window) {
+        // Write to IWDG WINR the IWDG_Window value to compare with. In any case,
+        // even if window feature is disabled, Watchdog will be reloaded by writing
+        // windows register
+        IWDG->WINR = this->window;
+    }
+    else {
+        // Reload IWDG counter with value defined in the reload register
+        IWDG->KR = IWDG_KEY_RELOAD;
+    }
+
+}
+
+void IndependentWatchdog::trigger()
+{
+    // Reload IWDG counter with value defined in the reload register
+    IWDG->KR = IWDG_KEY_RELOAD;
+}
diff --git a/platform/stm32g0xx/IndependentWatchdog.h b/platform/stm32g0xx/IndependentWatchdog.h
new file mode 100644
index 0000000..7390402
--- /dev/null
+++ b/platform/stm32g0xx/IndependentWatchdog.h
@@ -0,0 +1,24 @@
+#ifndef __PLATFORM_STM32G0XX_INDEPENDENTWATCHDOG_H__
+#define __PLATFORM_STM32G0XX_INDEPENDENTWATCHDOG_H__
+
+#include <cstdint>
+
+#include "stm32g0xx.h"
+
+namespace perinet::platform::stm32g0xx {
+
+class IndependentWatchdog
+{
+public:
+    IndependentWatchdog(uint32_t, uint32_t);
+    void enable();
+    void trigger();
+
+private:
+    uint32_t window;
+    uint32_t reload;
+};
+
+}
+
+#endif