drivers: watchdog: gecko: Fix API corner cases

Properly return the correct error codes when the watchdog API
is misused. Fail timeout install if WDT_FLAG_RESET_CPU_CORE is
set, a watchdog reset will at a minimum cause a soft reset of
the entire SoC.

Signed-off-by: Aksel Skauge Mellbye <[email protected]>

Author: asmellby

drivers/watchdog/wdt_gecko.c

@@ -87,12 +87,25 @@ static int wdt_gecko_convert_window(uint32_t window, uint32_t period)
 	return idx;
 }
 
+static bool wdt_gecko_is_enabled(WDOG_TypeDef *wdog)
+{
+#if defined(CONFIG_SOC_FAMILY_SILABS_S2)
+	return FIELD_GET(WDOG_EN_EN, wdog->EN);
+#else
+	return FIELD_GET(WDOG_CTRL_EN, wdog->CTRL);
+#endif
+}
+
 static int wdt_gecko_setup(const struct device *dev, uint8_t options)
 {
 	const struct wdt_gecko_cfg *config = dev->config;
 	struct wdt_gecko_data *data = dev->data;
 	WDOG_TypeDef *wdog = config->base;
 
+	if (wdt_gecko_is_enabled(wdog)) {
+		return -EBUSY;
+	}
+
 	if (!data->timeout_installed) {
 		LOG_ERR("No valid timeouts installed");
 		return -EINVAL;
@@ -134,8 +147,14 @@ static int wdt_gecko_disable(const struct device *dev)
 	struct wdt_gecko_data *data = dev->data;
 	WDOG_TypeDef *wdog = config->base;
 
-	WDOGn_Enable(wdog, false);
+	/* Always uninstall timeouts, independent of watchdog enable state */
 	data->timeout_installed = false;
+
+	if (!wdt_gecko_is_enabled(wdog)) {
+		return -EFAULT;
+	}
+
+	WDOGn_Enable(wdog, false);
 	LOG_DBG("Disabled the watchdog");
 
 	return 0;
@@ -144,10 +163,16 @@ static int wdt_gecko_disable(const struct device *dev)
 static int wdt_gecko_install_timeout(const struct device *dev,
 				     const struct wdt_timeout_cfg *cfg)
 {
+	const struct wdt_gecko_cfg *config = dev->config;
 	struct wdt_gecko_data *data = dev->data;
-	data->wdog_config = (WDOG_Init_TypeDef)WDOG_INIT_DEFAULT;
 	uint32_t installed_timeout;
 
+	data->wdog_config = (WDOG_Init_TypeDef)WDOG_INIT_DEFAULT;
+
+	if (wdt_gecko_is_enabled(config->base)) {
+		return -EBUSY;
+	}
+
 	if (data->timeout_installed) {
 		LOG_ERR("No more timeouts can be installed");
 		return -ENOMEM;
@@ -189,13 +214,12 @@ static int wdt_gecko_install_timeout(const struct device *dev,
 	/* Set mode of watchdog and callback */
 	switch (cfg->flags) {
 	case WDT_FLAG_RESET_SOC:
-	case WDT_FLAG_RESET_CPU_CORE:
 		if (cfg->callback != NULL) {
 			LOG_ERR("Reset mode with callback not supported\n");
 			return -ENOTSUP;
 		}
 		data->wdog_config.resetDisable = false;
-		LOG_DBG("Configuring reset CPU/SoC mode\n");
+		LOG_DBG("Configuring reset SoC mode\n");
 		break;
 
 	case WDT_FLAG_RESET_NONE:
@@ -204,6 +228,10 @@ static int wdt_gecko_install_timeout(const struct device *dev,
 		LOG_DBG("Configuring non-reset mode\n");
 		break;
 
+	case WDT_FLAG_RESET_CPU_CORE:
+		LOG_ERR("CPU core only reset not supported");
+		return -ENOTSUP;
+
 	default:
 		LOG_ERR("Unsupported watchdog config flag");
 		return -EINVAL;
@@ -224,6 +252,10 @@ static int wdt_gecko_feed(const struct device *dev, int channel_id)
 		return -EINVAL;
 	}
 
+	if (!wdt_gecko_is_enabled(wdog)) {
+		return -EINVAL;
+	}
+
 	WDOGn_Feed(wdog);
 	LOG_DBG("Fed the watchdog");