samples: watchdog: add the ch32v003evt to the sample

drivers/watchdog/CMakeLists.txt

@@ -45,6 +45,7 @@ zephyr_library_sources_ifdef(CONFIG_WDT_AMBIQ wdt_ambiq.c)
 zephyr_library_sources_ifdef(CONFIG_WDT_XMC4XXX wdt_xmc4xxx.c)
 zephyr_library_sources_ifdef(CONFIG_WWDT_NUMAKER wdt_wwdt_numaker.c)
 zephyr_library_sources_ifdef(CONFIG_WDT_ENE_KB1200 wdt_ene_kb1200.c)
+zephyr_library_sources_ifdef(CONFIG_WDT_IWDG_CH32V00X wdt_iwdg_ch32v00x.c)
 
 zephyr_library_sources_ifdef(CONFIG_WDT_DW wdt_dw.c wdt_dw_common.c)
 zephyr_library_sources_ifdef(CONFIG_WDT_INTEL_ADSP wdt_intel_adsp.c wdt_dw_common.c)

drivers/watchdog/Kconfig

@@ -134,4 +134,6 @@ source "drivers/watchdog/Kconfig.ene"
 
 source "drivers/watchdog/Kconfig.litex"
 
+source "drivers/watchdog/Kconfig.ch32v00x"
+
 endif # WATCHDOG

drivers/watchdog/Kconfig.ch32v00x

@@ -0,0 +1,9 @@
+# Copyright (c) 2024 Google LLC.
+# SPDX-License-Identifier: Apache-2.0
+
+config WDT_IWDG_CH32V00X
+	bool "CH32V00x Independent Watchdog (IWDG) driver"
+	default y
+	depends on DT_HAS_WCH_IWDG_ENABLED
+	help
+	  Enable the Independent Watchdog (IWDG) driver for CH32V00x SOCs.

drivers/watchdog/wdt_iwdg_ch32v00x.c

@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2024 Google LLC.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT wch_iwdg
+
+#include <zephyr/drivers/watchdog.h>
+#include <zephyr/kernel.h>
+#include <zephyr/sys_clock.h>
+#include <errno.h>
+
+#include <ch32_iwdg.h>
+
+static int iwdg_ch32v00x_setup(const struct device *dev, uint8_t options)
+{
+	if (options != 0) {
+		return -ENOTSUP;
+	}
+
+	IWDG->CTLR = CTLR_KEY_Enable;
+
+	return 0;
+}
+
+static int iwdg_ch32v00x_disable(const struct device *dev)
+{
+	return -EPERM;
+}
+
+static int iwdg_ch32v00x_install_timeout(const struct device *dev,
+					 const struct wdt_timeout_cfg *config)
+{
+	/* The IWDT is driven by the 128 kHz LSI oscillator with at least a /4 prescaler. */
+	int prescaler = 0;
+	uint32_t reload = config->window.max * (128 / 4);
+
+	if (config->callback != NULL) {
+		return -ENOTSUP;
+	}
+	if (config->window.min != 0) {
+		return -ENOTSUP;
+	}
+	if ((config->flags & WDT_FLAG_RESET_MASK) != WDT_FLAG_RESET_CPU_CORE) {
+		return -ENOTSUP;
+	}
+
+	for (; reload > IWDG_RL && prescaler < IWDG_PR;) {
+		prescaler++;
+		reload /= 2;
+	}
+	/* The highest prescaler is effectively invalid. Use that to detect a too long timeout. */
+	if (prescaler == IWDG_PR) {
+		return -EINVAL;
+	}
+
+	/* Wait for the watchdog to be idle, unlock it, update, and wait for idle. */
+	while ((IWDG->STATR & (IWDG_RVU | IWDG_PVU)) != 0) {
+	}
+
+	IWDG->CTLR = IWDG_WriteAccess_Enable;
+	IWDG->PSCR = prescaler;
+	IWDG->RLDR = reload;
+
+	while ((IWDG->STATR & (IWDG_RVU | IWDG_PVU)) != 0) {
+	}
+
+	return 0;
+}
+
+static int iwdg_ch32v00x_feed(const struct device *dev, int channel_id)
+{
+	IWDG->CTLR = CTLR_KEY_Reload;
+
+	return 0;
+}
+
+static const struct wdt_driver_api iwdg_ch32v00x_api = {
+	.setup = iwdg_ch32v00x_setup,
+	.disable = iwdg_ch32v00x_disable,
+	.install_timeout = iwdg_ch32v00x_install_timeout,
+	.feed = iwdg_ch32v00x_feed,
+};
+
+static int iwdg_ch32v00x_init(const struct device *dev)
+{
+	return 0;
+}
+
+DEVICE_DT_INST_DEFINE(0, iwdg_ch32v00x_init, NULL, NULL, NULL, PRE_KERNEL_1,
+		      CONFIG_KERNEL_INIT_PRIORITY_DEVICE, &iwdg_ch32v00x_api);

dts/bindings/watchdog/wch,iwdg.yaml

@@ -0,0 +1,12 @@
+# Copyright (c) 2024 Google LLC.
+# SPDX-License-Identifier: Apache-2.0
+
+description: CH32V00x Independent Watchdog (IWDG)
+
+compatible: "wch,iwdg"
+
+include: base.yaml
+
+properties:
+  reg:
+    required: true

dts/riscv/wch/ch32v00x.dtsi

@@ -94,6 +94,11 @@
 			interrupts = <12>;
 		};
 
+		iwdg: watchdog@40003000 {
+			compatible = "wch,iwdg";
+			reg = <0x40003000 16>;
+		};
+
 		pwr: pwr@40007000 {
 			compatible = "wch,pwr";
 			reg = <0x40007000 16>;

modules/hal_wch/ch32_iwdg.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2024 Google LLC.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef _CH32_IWDG_H
+#define _CH32_IWDG_H
+
+#ifdef CONFIG_SOC_CH32V003
+#include <ch32v003fun.h>
+#else
+#error "SoC not supported!"
+#endif
+
+#endif

samples/drivers/watchdog/boards/ch32v003evt.overlay

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2024 Google LLC.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	aliases {
+		watchdog0 = &iwdg;
+	};
+};
+
+&iwdg {
+	status = "okay";
+};