gd32/driver: fix inaccurate WDT clock timeout feeding issue

Author: kurisaW

bsp/gd32/arm/libraries/gd32_drivers/drv_wdt.c

@@ -1,22 +1,42 @@
 /*
- * Copyright (c) 2006-2022, RT-Thread Development Team
+ * Copyright (c) 2006-2025, RT-Thread Development Team
  *
  * SPDX-License-Identifier: Apache-2.0
  *
  * Change Logs:
  * Date           Author            Notes
  * 2022-01-25     iysheng           first version
+ * 2025-10-09     kurisaw           fix inaccurate WDT clock timeout feeding issue
  */
 
+#include <rtthread.h>
+#include <rtdevice.h>
+#include <rthw.h>
 #include <board.h>
 
-#define DBG_TAG             "drv.wdt"
-#define DBG_LVL             DBG_INFO
+#define DBG_TAG "drv.wdt"
+#define DBG_LVL DBG_INFO
 #include <rtdbg.h>
 
 #ifdef RT_USING_WDT
 
-typedef struct {
+/* User-configurable macros for WDT clock source and prescaler */
+/* Default select oscillator type: RCU_LXTAL */
+#define WDT_OSCI_TYPE              RCU_LXTAL
+
+/* Prescaler divider value (must match WDT_PSC_VALUE) */
+#define WDT_PSC_DIVIDER            256U
+/* Prescaler register value */
+#define WDT_PSC_VALUE              FWDGT_PSC_DIV256
+
+/* Derived values */
+#define WDT_CLOCK_FREQ             LXTAL_VALUE
+
+#define WDT_TICK_HZ                (WDT_CLOCK_FREQ / WDT_PSC_DIVIDER)
+#define WDT_MAX_RELOAD_VALUE       0xfffU
+
+typedef struct
+{
     struct rt_watchdog_device wdt;
     rt_uint32_t min_threshold_s;
     rt_uint32_t max_threshold_s;
@@ -27,23 +47,34 @@ static gd32_wdt_device_t g_wdt_dev;
 
 static rt_err_t gd32_wdt_init(rt_watchdog_t *wdt)
 {
-    rcu_osci_on(RCU_IRC40K);
-    if (ERROR == rcu_osci_stab_wait(RCU_IRC40K))
+    /* Enable and wait for oscillator stabilization */
+    rcu_osci_on(WDT_OSCI_TYPE);
+    if (ERROR == rcu_osci_stab_wait(WDT_OSCI_TYPE))
     {
-        LOG_E("failed init IRC40K clock for free watchdog.");
+        LOG_E("failed init %s clock for free watchdog.", WDT_OSCI_TYPE);
         return -RT_EINVAL;
     }
 
-    g_wdt_dev.min_threshold_s = 1;
-    g_wdt_dev.max_threshold_s = (0xfff << 8) / 40000;
-    LOG_I("threshold section [%u, %d]", \
-        g_wdt_dev.min_threshold_s, g_wdt_dev.max_threshold_s);
+    /* Configure RTC clock source for FWDGT */
+    rcu_rtc_clock_config(WDT_OSCI_TYPE);
+
+    /* Calculate thresholds */
+    g_wdt_dev.min_threshold_s = 1U;
+    g_wdt_dev.max_threshold_s = ((WDT_MAX_RELOAD_VALUE + 1U) * WDT_PSC_DIVIDER) / WDT_CLOCK_FREQ;
+    LOG_I("WDT clock: %u Hz (tick: %u Hz), threshold section [%u, %u]",
+          WDT_CLOCK_FREQ, WDT_TICK_HZ,
+          g_wdt_dev.min_threshold_s, g_wdt_dev.max_threshold_s);
 
+    /* Configure FWDGT with max timeout */
     fwdgt_write_enable();
-    fwdgt_config(0xfff, FWDGT_PSC_DIV256);
+    if (fwdgt_config(WDT_MAX_RELOAD_VALUE, WDT_PSC_VALUE) != SUCCESS)
+    {
+        LOG_E("failed to configure FWDGT");
+        return -RT_ERROR;
+    }
     fwdgt_enable();
 
-    return 0;
+    return RT_EOK;
 }
 
 static rt_err_t gd32_wdt_control(rt_watchdog_t *wdt, int cmd, void *arg)
@@ -56,20 +87,26 @@ static rt_err_t gd32_wdt_control(rt_watchdog_t *wdt, int cmd, void *arg)
         fwdgt_counter_reload();
         break;
     case RT_DEVICE_CTRL_WDT_SET_TIMEOUT:
-        param = *(rt_uint32_t *) arg;
-        if ((param > g_wdt_dev.max_threshold_s) || \
+        param = *(rt_uint32_t *)arg;
+        if ((param > g_wdt_dev.max_threshold_s) ||
             (param < g_wdt_dev.min_threshold_s))
         {
-            LOG_E("invalid param@%u.", param);
+            LOG_E("invalid param@%u (out of [%u, %u])", param,
+                  g_wdt_dev.min_threshold_s, g_wdt_dev.max_threshold_s);
             return -RT_EINVAL;
         }
         else
         {
             g_wdt_dev.current_threshold_s = param;
+            rt_uint32_t reload_value = (param * WDT_TICK_HZ) - 1U;
+            fwdgt_write_enable();
+            if (fwdgt_config(reload_value, WDT_PSC_VALUE) != SUCCESS)
+            {
+                LOG_E("failed to set timeout %u s", param);
+                return -RT_ERROR;
+            }
+            fwdgt_write_disable();
         }
-        fwdgt_write_enable();
-        fwdgt_config(param * 40000 >> 8, FWDGT_PSC_DIV256);
-        fwdgt_write_disable();
         break;
     case RT_DEVICE_CTRL_WDT_GET_TIMEOUT:
         *(rt_uint32_t *)arg = g_wdt_dev.current_threshold_s;
@@ -92,17 +129,20 @@ static struct rt_watchdog_ops g_wdt_ops = {
 
 static int rt_hw_wdt_init(void)
 {
-    rt_err_t ret;
+    rt_err_t ret = RT_EOK;
 
     g_wdt_dev.wdt.ops = &g_wdt_ops;
     /* register watchdog device */
-    if (rt_hw_watchdog_register(&g_wdt_dev.wdt, "wdt", \
-        RT_DEVICE_FLAG_DEACTIVATE, RT_NULL) != RT_EOK)
+    if (rt_hw_watchdog_register(&g_wdt_dev.wdt, "wdt",
+                                RT_DEVICE_FLAG_DEACTIVATE, RT_NULL) != RT_EOK)
     {
         LOG_E("wdt device register failed.");
-        return -RT_ERROR;
+        ret = -RT_ERROR;
+    }
+    else
+    {
+        LOG_D("wdt device register success.");
     }
-    LOG_D("wdt device register success.");
 
     return ret;
 }