cpu/atmega_common: add implementation for watchdog

cpu/atmega_common/Makefile.features

@@ -4,3 +4,4 @@ FEATURES_PROVIDED += atmega_pcint0
 FEATURES_PROVIDED += periph_eeprom
 FEATURES_PROVIDED += periph_gpio periph_gpio_irq
 FEATURES_PROVIDED += periph_pm
+FEATURES_PROVIDED += periph_wdt

cpu/atmega_common/include/periph_cpu_common.h

@@ -151,6 +151,19 @@ typedef struct {
  */
 #define EEPROM_CLEAR_BYTE              (0xff)
 
+/**
+ * @name    WDT upper and lower bound times in ms
+ * @{
+ */
+#define NWDT_TIME_LOWER_LIMIT           (1)
+#define NWDT_TIME_UPPER_LIMIT           (8192U)
+/** @} */
+
+/**
+ * @brief   WDT can be stopped on AVR
+ */
+#define WDT_HAS_STOP                    (1)
+
 #ifdef __cplusplus
 }
 #endif

cpu/atmega_common/periph/wdt.c

@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2019 Inria
+ *
+ * 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_atmega_common
+ * @ingroup     drivers_periph_wdt
+ * @{
+ *
+ * @file
+ * @brief       Implementation of the watchdog peripheral interface
+ *
+ * @author      Alexandre Abadie <alexandre.abadie@inria.fr>
+ *
+ * @}
+ */
+
+#include "cpu.h"
+#include "periph/pm.h"
+#include "periph/wdt.h"
+
+#include <avr/interrupt.h>
+#include "avr/wdt.h"
+
+#define ENABLE_DEBUG (0)
+#include "debug.h"
+
+uint8_t wdt_prescaler = WDTO_15MS;
+
+void wdt_start(void)
+{
+    DEBUG("[wdt] start the watchdog\n");
+    wdt_enable(wdt_prescaler);
+}
+
+void wdt_stop(void)
+{
+    DEBUG("[wdt] stop the watchdog\n");
+    wdt_disable();
+}
+
+void wdt_kick(void)
+{
+    DEBUG("[wdt] reload the watchdog\n");
+    wdt_reset();
+    wdt_enable(wdt_prescaler);
+}
+
+void wdt_setup_reboot(uint32_t min_time, uint32_t max_time)
+{
+    (void)min_time;
+
+    /* Windowed wdt not supported */
+    assert(min_time == 0);
+
+    /* Check reset time limit */
+    assert((max_time > NWDT_TIME_LOWER_LIMIT) || \
+           (max_time < NWDT_TIME_UPPER_LIMIT));
+
+    /* disable watchdog */
+    wdt_disable();
+
+    if (max_time >= 8000) {
+        wdt_prescaler = WDTO_8S;
+    }
+    else if (max_time >= 4000) {
+        wdt_prescaler = WDTO_4S;
+    }
+    else if (max_time >= 2000) {
+        wdt_prescaler = WDTO_2S;
+    }
+    else if (max_time >= 1000) {
+        wdt_prescaler = WDTO_1S;
+    }
+    else if (max_time >= 500) {
+        wdt_prescaler = WDTO_500MS;
+    }
+    else if (max_time >= 250) {
+        wdt_prescaler = WDTO_250MS;
+    }
+    else if (max_time >= 125) {
+        wdt_prescaler = WDTO_120MS;
+    }
+    else if (max_time >= 64) {
+        wdt_prescaler = WDTO_60MS;
+    }
+    else if (max_time >= 32) {
+        wdt_prescaler = WDTO_30MS;
+    }
+    else {
+        wdt_prescaler = WDTO_15MS;
+    }
+
+    DEBUG("[wdt] watchdog setup complete\n");
+}