--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2024 Google LLC.
+ * Author: Lukasz Majczak <lma@chromium.com>
+ */
+
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_data/cros_ec_commands.h>
+#include <linux/platform_data/cros_ec_proto.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+#define CROS_EC_WATCHDOG_DEFAULT_TIME 30 /* seconds */
+#define DRV_NAME "cros-ec-wdt"
+
+union cros_ec_wdt_data {
+ struct ec_params_hang_detect req;
+ struct ec_response_hang_detect resp;
+} __packed;
+
+static int cros_ec_wdt_send_cmd(struct cros_ec_device *cros_ec,
+ union cros_ec_wdt_data *arg)
+{
+ int ret;
+ struct {
+ struct cros_ec_command msg;
+ union cros_ec_wdt_data data;
+ } __packed buf = {
+ .msg = {
+ .version = 0,
+ .command = EC_CMD_HANG_DETECT,
+ .insize = (arg->req.command == EC_HANG_DETECT_CMD_GET_STATUS) ?
+ sizeof(struct ec_response_hang_detect) :
+ 0,
+ .outsize = sizeof(struct ec_params_hang_detect),
+ },
+ .data.req = arg->req
+ };
+
+ ret = cros_ec_cmd_xfer_status(cros_ec, &buf.msg);
+ if (ret < 0)
+ return ret;
+
+ arg->resp = buf.data.resp;
+
+ return 0;
+}
+
+static int cros_ec_wdt_ping(struct watchdog_device *wdd)
+{
+ struct cros_ec_device *cros_ec = watchdog_get_drvdata(wdd);
+ union cros_ec_wdt_data arg;
+ int ret;
+
+ arg.req.command = EC_HANG_DETECT_CMD_RELOAD;
+ ret = cros_ec_wdt_send_cmd(cros_ec, &arg);
+ if (ret < 0)
+ dev_dbg(wdd->parent, "Failed to ping watchdog (%d)", ret);
+
+ return ret;
+}
+
+static int cros_ec_wdt_start(struct watchdog_device *wdd)
+{
+ struct cros_ec_device *cros_ec = watchdog_get_drvdata(wdd);
+ union cros_ec_wdt_data arg;
+ int ret;
+
+ /* Prepare watchdog on EC side */
+ arg.req.command = EC_HANG_DETECT_CMD_SET_TIMEOUT;
+ arg.req.reboot_timeout_sec = wdd->timeout;
+ ret = cros_ec_wdt_send_cmd(cros_ec, &arg);
+ if (ret < 0)
+ dev_dbg(wdd->parent, "Failed to start watchdog (%d)", ret);
+
+ return ret;
+}
+
+static int cros_ec_wdt_stop(struct watchdog_device *wdd)
+{
+ struct cros_ec_device *cros_ec = watchdog_get_drvdata(wdd);
+ union cros_ec_wdt_data arg;
+ int ret;
+
+ arg.req.command = EC_HANG_DETECT_CMD_CANCEL;
+ ret = cros_ec_wdt_send_cmd(cros_ec, &arg);
+ if (ret < 0)
+ dev_dbg(wdd->parent, "Failed to stop watchdog (%d)", ret);
+
+ return ret;
+}
+
+static int cros_ec_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
+{
+ unsigned int old_timeout = wdd->timeout;
+ int ret;
+
+ wdd->timeout = t;
+ ret = cros_ec_wdt_start(wdd);
+ if (ret < 0)
+ wdd->timeout = old_timeout;
+
+ return ret;
+}
+
+static const struct watchdog_info cros_ec_wdt_ident = {
+ .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+ .firmware_version = 0,
+ .identity = DRV_NAME,
+};
+
+static const struct watchdog_ops cros_ec_wdt_ops = {
+ .owner = THIS_MODULE,
+ .ping = cros_ec_wdt_ping,
+ .start = cros_ec_wdt_start,
+ .stop = cros_ec_wdt_stop,
+ .set_timeout = cros_ec_wdt_set_timeout,
+};
+
+static int cros_ec_wdt_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
+ struct cros_ec_device *cros_ec = ec_dev->ec_dev;
+ struct watchdog_device *wdd;
+ union cros_ec_wdt_data arg;
+ int ret = 0;
+
+ wdd = devm_kzalloc(&pdev->dev, sizeof(*wdd), GFP_KERNEL);
+ if (!wdd)
+ return -ENOMEM;
+
+ arg.req.command = EC_HANG_DETECT_CMD_GET_STATUS;
+ ret = cros_ec_wdt_send_cmd(cros_ec, &arg);
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "Failed to get watchdog bootstatus");
+
+ wdd->parent = &pdev->dev;
+ wdd->info = &cros_ec_wdt_ident;
+ wdd->ops = &cros_ec_wdt_ops;
+ wdd->timeout = CROS_EC_WATCHDOG_DEFAULT_TIME;
+ wdd->min_timeout = EC_HANG_DETECT_MIN_TIMEOUT;
+ wdd->max_timeout = EC_HANG_DETECT_MAX_TIMEOUT;
+ if (arg.resp.status == EC_HANG_DETECT_AP_BOOT_EC_WDT)
+ wdd->bootstatus = WDIOF_CARDRESET;
+
+ arg.req.command = EC_HANG_DETECT_CMD_CLEAR_STATUS;
+ ret = cros_ec_wdt_send_cmd(cros_ec, &arg);
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "Failed to clear watchdog bootstatus");
+
+ watchdog_stop_on_reboot(wdd);
+ watchdog_stop_on_unregister(wdd);
+ watchdog_set_drvdata(wdd, cros_ec);
+ platform_set_drvdata(pdev, wdd);
+
+ return devm_watchdog_register_device(dev, wdd);
+}
+
+static int __maybe_unused cros_ec_wdt_suspend(struct platform_device *pdev, pm_message_t state)
+{
+ struct watchdog_device *wdd = platform_get_drvdata(pdev);
+ int ret = 0;
+
+ if (watchdog_active(wdd))
+ ret = cros_ec_wdt_stop(wdd);
+
+ return ret;
+}
+
+static int __maybe_unused cros_ec_wdt_resume(struct platform_device *pdev)
+{
+ struct watchdog_device *wdd = platform_get_drvdata(pdev);
+ int ret = 0;
+
+ if (watchdog_active(wdd))
+ ret = cros_ec_wdt_start(wdd);
+
+ return ret;
+}
+
+static const struct platform_device_id cros_ec_wdt_id[] = {
+ { DRV_NAME, 0 },
+ {}
+};
+
+static struct platform_driver cros_ec_wdt_driver = {
+ .probe = cros_ec_wdt_probe,
+ .suspend = pm_ptr(cros_ec_wdt_suspend),
+ .resume = pm_ptr(cros_ec_wdt_resume),
+ .driver = {
+ .name = DRV_NAME,
+ },
+ .id_table = cros_ec_wdt_id,
+};
+
+module_platform_driver(cros_ec_wdt_driver);
+
+MODULE_DEVICE_TABLE(platform, cros_ec_wdt_id);
+MODULE_DESCRIPTION("Cros EC Watchdog Device Driver");
+MODULE_LICENSE("GPL");
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