zephyr: npcx: add system reset driver

This CL include the following:
1. Add cros_system_soc_reset() API for system reset.
2. Add NPCX soc reset driver. NPCX chip doesn't have the specific
system reset functionality. Use watchdog reset as the system reset.

BUG=b:176523207
BRANCH=None.
TEST=reset EC by 'reboot' console command

Signed-off-by: Wealian Liao <whliao@nuvoton.corp-partner.google.com>
Change-Id: Ia86bfac548ef48e18e501a29f3cbb632f33a3e8a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2698739
Reviewed-by: Simon Glass <sjg@chromium.org>
Commit-Queue: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>

3 files changed, 125 insertions, 5 deletions

diff --git a/zephyr/drivers/cros_system/cros_system_npcx.c b/zephyr/drivers/cros_system/cros_system_npcx.c
index 87db955e4a..b63743a13d 100644
--- a/zephyr/drivers/cros_system/cros_system_npcx.c
+++ b/zephyr/drivers/cros_system/cros_system_npcx.c
@@ -4,6 +4,7 @@
  */
 
 #include <drivers/cros_system.h>
+#include <drivers/watchdog.h>
 #include <logging/log.h>
 #include <soc.h>
 
@@ -29,6 +30,16 @@ struct cros_system_npcx_data {
 
 #define DRV_DATA(dev) ((struct cros_system_npcx_data *)(dev)->data)
 
+/*
+ * For cortex-m we cannot use irq_lock() for disabling all the interrupts
+ * because it leaves some (NMI and faults) still enabled. Use "cpsid i" to
+ * replace it.
+ */
+static inline void interrupt_disable_all(void)
+{
+	__asm__("cpsid i");
+}
+
 static int cros_system_npcx_get_reset_cause(const struct device *dev)
 {
 	struct cros_system_npcx_data *data = DRV_DATA(dev);
@@ -58,6 +69,52 @@ static int cros_system_npcx_init(const struct device *dev)
 	return 0;
 }
 
+static int cros_system_npcx_soc_reset(const struct device *dev)
+{
+	struct twd_reg *const inst_twd = HAL_TWD_INST(dev);
+
+	/* Disable interrupts to avoid task swaps during reboot */
+	interrupt_disable_all();
+
+	/*
+	 * NPCX chip doesn't have the specific system reset functionality. Use
+	 * watchdog reset as a system reset.
+	 */
+
+	/* Stop the watchdog */
+	if (IS_ENABLED(CONFIG_WATCHDOG)) {
+		const struct device *wdt_dev = device_get_binding(
+			DT_LABEL(DT_INST(0, nuvoton_npcx_watchdog)));
+
+		if (!wdt_dev) {
+			LOG_ERR("wdt_dev get binding failed");
+			return -ENODEV;
+		}
+
+		wdt_disable(wdt_dev);
+	}
+
+	/* Enable early touch */
+	inst_twd->T0CSR &= ~BIT(NPCX_T0CSR_TESDIS);
+	inst_twd->TWCFG |= BIT(NPCX_TWCFG_WDSDME);
+
+	/*
+	 * The trigger of a watchdog event by a "too early service" condition.
+	 * When the watchdog is written more than once during three watchdog
+	 * clock cycle.
+	 */
+	inst_twd->WDSDM = 0x5C;
+	inst_twd->WDSDM = 0x5C;
+
+	/* Wait for the soc reset. */
+	while (1) {
+		;
+	}
+
+	/* should never return */
+	return 0;
+}
+
 static struct cros_system_npcx_data cros_system_npcx_dev_data;
 
 static const struct cros_system_npcx_config cros_system_dev_cfg = {
@@ -67,6 +124,7 @@ static const struct cros_system_npcx_config cros_system_dev_cfg = {
 
 static const struct cros_system_driver_api cros_system_driver_npcx_api = {
 	.get_reset_cause = cros_system_npcx_get_reset_cause,
+	.soc_reset = cros_system_npcx_soc_reset,
 };
 
 /*
diff --git a/zephyr/include/drivers/cros_system.h b/zephyr/include/drivers/cros_system.h
index 489c86a6f7..8c5b24ef2f 100644
--- a/zephyr/include/drivers/cros_system.h
+++ b/zephyr/include/drivers/cros_system.h
@@ -3,16 +3,28 @@
  * found in the LICENSE file.
  */
 
+/**
+ * @file
+ * @brief Public API for cros system drivers
+ */
+
 #ifndef ZEPHYR_INCLUDE_DRIVERS_CROS_SYSTEM_H_
 #define ZEPHYR_INCLUDE_DRIVERS_CROS_SYSTEM_H_
 
+/**
+ * @brief cros system Interface
+ * @defgroup cros_system_interface cros system Interface
+ * @ingroup io_interfaces
+ * @{
+ */
+
 #include <kernel.h>
 #include <device.h>
 
 /**
- * @brief CROS system driver APIs
+ * @brief system_reset_cause enum
+ * Identify the reset cause.
  */
-
 enum system_reset_cause {
 	/* the reset is triggered by VCC power-up */
 	POWERUP = 0,
@@ -26,10 +38,24 @@ enum system_reset_cause {
 	UNKNOWN_RST,
 };
 
+/**
+ * @typedef cros_system_get_reset_cause_api
+ * @brief Callback API for getting reset cause instance.
+ * See cros_system_get_reset_cause() for argument descriptions
+ */
 typedef int (*cros_system_get_reset_cause_api)(const struct device *dev);
 
+/**
+ * @typedef cros_system_soc_reset_api
+ * @brief Callback API for soc-reset instance.
+ * See cros_system_soc_reset() for argument descriptions
+ */
+typedef int (*cros_system_soc_reset_api)(const struct device *dev);
+
+/** @brief Driver API structure. */
 __subsystem struct cros_system_driver_api {
 	cros_system_get_reset_cause_api get_reset_cause;
+	cros_system_soc_reset_api soc_reset;
 };
 
 /**
@@ -55,6 +81,28 @@ static inline int z_impl_cros_system_get_reset_cause(const struct device *dev)
 }
 
 /**
+ * @brief reset the soc
+ *
+ * @param dev Pointer to the device structure for the driver instance.
+ *
+ * @retval no return if successful.
+ * @retval Negative errno code if failure.
+ */
+__syscall int cros_system_soc_reset(const struct device *dev);
+
+static inline int z_impl_cros_system_soc_reset(const struct device *dev)
+{
+	const struct cros_system_driver_api *api =
+		(const struct cros_system_driver_api *)dev->api;
+
+	if (!api->soc_reset) {
+		return -ENOTSUP;
+	}
+
+	return api->soc_reset(dev);
+}
+
+/**
  * @}
  */
 #include <syscalls/cros_system.h>
diff --git a/zephyr/shim/chip/npcx/system.c b/zephyr/shim/chip/npcx/system.c
index e86d77a7fd..4e25363415 100644
--- a/zephyr/shim/chip/npcx/system.c
+++ b/zephyr/shim/chip/npcx/system.c
@@ -3,16 +3,30 @@
  * found in the LICENSE file.
  */
 
+#include <drivers/cros_system.h>
+#include <logging/log.h>
+
 #include "system.h"
 
+LOG_MODULE_REGISTER(shim_npcx_system, LOG_LEVEL_ERR);
+
 void system_reset(int flags)
 {
+	const struct device *sys_dev = device_get_binding("CROS_SYSTEM");
+	int err;
+
+	if (!sys_dev)
+		LOG_ERR("sys_dev get binding failed");
+
 	/*
-	 * TODO(b/176523207): Reset the system. NPCX uses Watchdog & BBRAM for
-	 * system reset & reset flag saving. The function could be implemented
-	 * after Watchdog & BBRAM land the zephyr repository.
+	 * TODO(b/176523207): reset flag & SYSTEM_RESET_WAIT_EXT
 	 */
 
+	err = cros_system_soc_reset(sys_dev);
+
+	if (err < 0)
+		LOG_ERR("soc reset failed");
+
 	while (1)
 		;
 }