Merge pull request #12663 from aabadie/pr/cpu/fe310_watchdog

cpu/fe310: implement driver for watchdog

cpu/fe310/Makefile.features

@@ -4,4 +4,5 @@ FEATURES_PROVIDED += cpp
 FEATURES_PROVIDED += periph_cpuid
 FEATURES_PROVIDED += periph_gpio periph_gpio_irq
 FEATURES_PROVIDED += periph_pm
+FEATURES_PROVIDED += periph_wdt
 FEATURES_PROVIDED += ssp

cpu/fe310/include/periph_cpu.h

@@ -138,6 +138,28 @@ typedef struct {
     i2c_speed_t speed;          /**< I2C speed */
 } i2c_conf_t;
 
+/**
+ * @name    WDT upper and lower bound times in ms
+ * @{
+ */
+#define NWDT_TIME_LOWER_LIMIT           (1)
+/* Ensure the internal "count" variable stays within the uint32 bounds.
+  This variable corresponds to max_time * RTC_FREQ / MS_PER_SEC. On fe310,
+  RTC_FREQ is 32768Hz. The 15 right shift is equivalent to a division by RTC_FREQ.
+ */
+#define NWDT_TIME_UPPER_LIMIT           ((UINT32_MAX >> 15)  * MS_PER_SEC + 1)
+/** @} */
+
+/**
+ * @brief   WDT interrupt priority: use highest priority
+ */
+#define WDT_INTR_PRIORITY               (PLIC_NUM_PRIORITIES)
+
+/**
+ * @brief   WDT can be stopped
+ */
+#define WDT_HAS_STOP                    (1)
+
 #ifdef __cplusplus
 }
 #endif

cpu/fe310/periph/wdt.c

@@ -0,0 +1,98 @@
+/*
+ * 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_fe310
+ * @ingroup     drivers_periph_wdt
+ * @{
+ *
+ * @file
+ * @brief       Implementation of the watchdog peripheral interface
+ *
+ * @author      Alexandre Abadie <alexandre.abadie@inria.fr>
+ *
+ * @}
+ */
+
+#include <inttypes.h>
+#include <assert.h>
+
+#include "cpu.h"
+#include "timex.h"
+
+#include "periph/wdt.h"
+
+#include "vendor/aon.h"
+
+#define ENABLE_DEBUG (0)
+#include "debug.h"
+
+void wdt_start(void)
+{
+    DEBUG("[wdt] start watchdog\n");
+
+    AON_REG(AON_WDOGKEY) = AON_WDOGKEY_VALUE;
+    AON_REG(AON_WDOGCFG) |= AON_WDOGCFG_ENCOREAWAKE;
+}
+
+void wdt_stop(void)
+{
+    DEBUG("[wdt] stop watchdog\n");
+
+    AON_REG(AON_WDOGKEY) = AON_WDOGKEY_VALUE;
+    AON_REG(AON_WDOGCFG) &= ~(AON_WDOGCFG_ENCOREAWAKE);
+}
+
+void wdt_kick(void)
+{
+    DEBUG("[wdt] reload the watchdog\n");
+
+    AON_REG(AON_WDOGKEY) = AON_WDOGKEY_VALUE;
+    AON_REG(AON_WDOGFEED) = AON_WDOGFEED_VALUE;
+}
+
+static inline uint8_t _scale(uint32_t count)
+{
+    uint8_t scale = 0;
+    while (count > (UINT16_MAX - 1)) {
+        count >>= 1;
+        scale++;
+    }
+
+    return scale;
+}
+
+static inline uint8_t _setup(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));
+
+    uint32_t count = ((uint32_t)max_time * RTC_FREQ) / MS_PER_SEC;
+    uint8_t scale = _scale(count);
+
+    AON_REG(AON_WDOGKEY) = AON_WDOGKEY_VALUE;
+    AON_REG(AON_WDOGCMP) = count;
+
+    return scale;
+}
+
+void wdt_setup_reboot(uint32_t min_time, uint32_t max_time)
+{
+    uint8_t scale = _setup(min_time, max_time);
+
+    AON_REG(AON_WDOGKEY) = AON_WDOGKEY_VALUE;
+    AON_REG(AON_WDOGCFG) = AON_WDOGCFG_RSTEN | AON_WDOGCFG_ZEROCMP | scale;
+
+    DEBUG("[wdt] watchdog setup complete\n");
+}