[PATCH v2 6/8] Add Advantech EIO Watchdog driver

This commit adds the driver to control the Advantech EIO Watchdog block,
this block is included in the Advantech EIO Embedded Controller.

Signed-off-by: Ramiro Oliveira <[email protected]>
---
 MAINTAINERS                |   1 +
 drivers/watchdog/Kconfig   |   7 +
 drivers/watchdog/Makefile  |   1 +
 drivers/watchdog/eio_wdt.c | 641 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 650 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index d2d7d815ed44..8d35fd7c5599 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -617,6 +617,7 @@ F:	drivers/hwmon/eio-hwmon.c
 F:	drivers/i2c/busses/i2c-eio.c
 F:	drivers/mfd/eio_core.c
 F:	drivers/video/backlight/eio_bl.c
+F:	drivers/watchdog/eio_wdt.c
 F:	include/linux/mfd/eio.h
 
 ADVANTECH SWBTN DRIVER
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 9f013d774897..bc0f13f4f79c 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -265,6 +265,13 @@ config DA9062_WATCHDOG
 
 	  This driver can be built as a module. The module name is da9062_wdt.
 
+config EIO_WATCHDOG
+	tristate "Advantech EIO Watchdog"
+	depends on MFD_EIO
+	help
+	  Watchdog timer driver for the Advantech EIO.
+	  If unsure, say N.
+
 config GPIO_WATCHDOG
 	tristate "Watchdog device controlled through GPIO-line"
 	depends on GPIOLIB && (ACPI || OF)
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index cb78e9932eae..eee059cfe1da 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -229,6 +229,7 @@ obj-$(CONFIG_DA9052_WATCHDOG) += da9052_wdt.o
 obj-$(CONFIG_DA9055_WATCHDOG) += da9055_wdt.o
 obj-$(CONFIG_DA9062_WATCHDOG) += da9062_wdt.o
 obj-$(CONFIG_DA9063_WATCHDOG) += da9063_wdt.o
+obj-$(CONFIG_EIO_WATCHDOG) += eio_wdt.o
 obj-$(CONFIG_GPIO_WATCHDOG)	+= gpio_wdt.o
 obj-$(CONFIG_WDAT_WDT) += wdat_wdt.o
 obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
diff --git a/drivers/watchdog/eio_wdt.c b/drivers/watchdog/eio_wdt.c
new file mode 100644
index 000000000000..b3c036a004b3
--- /dev/null
+++ b/drivers/watchdog/eio_wdt.c
@@ -0,0 +1,641 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Advantech EIO Watchdog Driver
+ *
+ * Copyright (C) 2025 Advantech Co., Ltd.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/eio.h>
+#include <linux/module.h>
+#include <linux/reboot.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+
+#define WATCHDOG_TIMEOUT	60
+#define WATCHDOG_PRETIMEOUT	10
+
+/* Support Flags */
+#define SUPPORT_AVAILABLE	BIT(0)
+#define SUPPORT_PWRBTN		BIT(3)
+#define SUPPORT_IRQ		BIT(4)
+#define SUPPORT_SCI		BIT(5)
+#define SUPPORT_PIN		BIT(6)
+#define SUPPORT_RESET		BIT(7)
+
+/* PMC registers */
+#define REG_STATUS		0x00
+#define REG_CONTROL		0x02
+#define REG_EVENT		0x10
+#define REG_PWR_EVENT_TIME	0x12
+#define REG_IRQ_EVENT_TIME	0x13
+#define REG_RESET_EVENT_TIME	0x14
+#define REG_PIN_EVENT_TIME	0x15
+#define REG_SCI_EVENT_TIME	0x16
+#define REG_IRQ_NUMBER		0x17
+
+/* PMC command and control */
+#define CMD_WDT_WRITE		0x2A
+#define CMD_WDT_READ		0x2B
+#define CTRL_STOP		0x00
+#define CTRL_START		0x01
+#define CTRL_TRIGGER		0x02
+
+/* I/O register and its flags */
+#define IOREG_UNLOCK		0x87
+#define IOREG_LOCK		0xAA
+#define IOREG_LDN		0x07
+#define IOREG_LDN_PMCIO		0x0F
+#define IOREG_IRQ		0x70
+#define IOREG_WDT_STATUS	0x30
+
+/* Flags */
+#define FLAG_WDT_ENABLED	0x01
+#define FLAG_TRIGGER_IRQ	BIT(4)
+
+/* Mapping event type to supported bit */
+#define EVENT_BIT(type)	BIT(type + 2)
+
+enum event_type {
+	EVENT_NONE,
+	EVENT_PWRBTN,
+	EVENT_IRQ,
+	EVENT_SCI,
+	EVENT_PIN
+};
+
+struct eio_wdt_dev {
+	u32 event_type;
+	u32 support;
+	int irq;
+	unsigned long last_time;
+	struct regmap *iomap;
+	struct device *mfd;
+	struct device *dev;
+	struct watchdog_device wdd;
+	struct eio_dev *core;
+};
+
+static char * const type_strs[] = {
+	"NONE",
+	"PWRBTN",
+	"IRQ",
+	"SCI",
+	"PIN",
+};
+
+static u32 type_regs[] = {
+	REG_RESET_EVENT_TIME,
+	REG_PWR_EVENT_TIME,
+	REG_IRQ_EVENT_TIME,
+	REG_SCI_EVENT_TIME,
+	REG_PIN_EVENT_TIME,
+};
+
+/* Specify the pin triggered on pretimeout or timeout */
+static char *event_type = "NONE";
+module_param(event_type, charp, 0);
+MODULE_PARM_DESC(event_type, "Watchdog timeout event type (NONE, PWRBTN, IRQ, SCI, PIN)");
+
+static int pmc_write(struct device *dev, u8 ctrl, void *data)
+{
+	struct pmc_op op = {
+		.cmd       = CMD_WDT_WRITE,
+		.control   = ctrl,
+		.payload   = data,
+		.size     = (ctrl <= REG_EVENT) ? 1 :
+			    (ctrl >= REG_IRQ_NUMBER) ? 1 : 4,
+	};
+	return eio_core_pmc_operation(dev, &op);
+}
+
+static int pmc_read(struct device *dev, u8 ctrl, void *data)
+{
+	struct pmc_op op = {
+		.cmd       = CMD_WDT_READ,
+		.control   = ctrl,
+		.payload   = data,
+		.size     = (ctrl <= REG_EVENT) ? 1 :
+			    (ctrl >= REG_IRQ_NUMBER) ? 1 : 4,
+	};
+	return eio_core_pmc_operation(dev, &op);
+}
+
+static int wdt_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
+{
+	wdd->timeout = timeout;
+	return 0;
+}
+
+static int wdt_set_pretimeout(struct watchdog_device *wdd, unsigned int pretimeout)
+{
+	wdd->pretimeout = pretimeout;
+	return 0;
+}
+
+static int wdt_get_type(struct eio_wdt_dev *eio_wdt)
+{
+	int i;
+
+	for (i = 1; i < ARRAY_SIZE(type_strs); i++) {
+		if (strcasecmp(event_type, type_strs[i]) == 0) {
+			if ((eio_wdt->support & EVENT_BIT(i)) == 0) {
+				dev_err(eio_wdt->dev,
+					"This board doesn't support %s trigger type\n",
+					event_type);
+				return -EINVAL;
+			}
+			eio_wdt->event_type = i;
+			return 0;
+		}
+	}
+	return 0;
+}
+
+static int get_time(struct eio_wdt_dev *eio_wdt, u8 ctrl, u32 *val)
+{
+	int ret;
+
+	ret = pmc_read(eio_wdt->mfd, ctrl, val);
+	if (ret)
+		return ret;
+
+	/* ms to sec */
+	*val /= 1000;
+
+	return 0;
+}
+
+static int set_time(struct eio_wdt_dev *eio_wdt, u8 ctrl, u32 time)
+{
+	/* sec to ms */
+	time *= 1000;
+
+	return pmc_write(eio_wdt->mfd, ctrl, &time);
+}
+
+static int wdt_set_config(struct eio_wdt_dev *eio_wdt)
+{
+	int ret, type;
+	u32 event_time = 0;
+	u32 reset_time = 0;
+
+	if (eio_wdt->event_type > EVENT_PIN)
+		return -EFAULT;
+
+	/* Calculate event time and reset time */
+	if (eio_wdt->wdd.pretimeout && eio_wdt->wdd.timeout) {
+		if (eio_wdt->wdd.timeout < eio_wdt->wdd.pretimeout)
+			return -EINVAL;
+
+		reset_time = eio_wdt->wdd.timeout;
+		event_time = eio_wdt->wdd.timeout - eio_wdt->wdd.pretimeout;
+
+	} else if (eio_wdt->wdd.timeout) {
+		reset_time = eio_wdt->event_type ?	0 : eio_wdt->wdd.timeout;
+		event_time = eio_wdt->event_type ? eio_wdt->wdd.timeout : 0;
+	}
+
+	/* Set reset time */
+	ret = set_time(eio_wdt, REG_RESET_EVENT_TIME, reset_time);
+	if (ret)
+		return ret;
+
+	/* Set every other times */
+	for (type = 1; type < ARRAY_SIZE(type_regs); type++) {
+		ret = set_time(eio_wdt, type_regs[type],
+			       (eio_wdt->event_type == type) ? event_time : 0);
+		if (ret)
+			return ret;
+	}
+
+	dev_dbg(eio_wdt->dev, "Config wdt reset time %u\n", reset_time);
+	dev_dbg(eio_wdt->dev, "Config wdt event time %u\n", event_time);
+	dev_dbg(eio_wdt->dev, "Config wdt event type %s\n",
+		type_strs[eio_wdt->event_type]);
+
+	return 0;
+}
+
+static int wdt_get_config(struct eio_wdt_dev *eio_wdt)
+{
+	int ret, type;
+	u32 event_time = 0, reset_time = 0;
+
+	/* Get Reset Time */
+	ret = get_time(eio_wdt, REG_RESET_EVENT_TIME, &reset_time);
+	if (ret)
+		return ret;
+
+	dev_dbg(eio_wdt->dev, "Timeout H/W default timeout: %u secs\n", reset_time);
+
+	/* Get every other times */
+	for (type = 1; type < ARRAY_SIZE(type_regs); type++) {
+		if ((eio_wdt->support & EVENT_BIT(type)) == 0)
+			continue;
+
+		ret = get_time(eio_wdt, type_regs[type], &event_time);
+		if (ret)
+			return ret;
+
+		if (event_time == 0)
+			continue;
+
+		if (reset_time) {
+			if (reset_time < event_time)
+				continue;
+
+			eio_wdt->wdd.timeout    = reset_time;
+			eio_wdt->wdd.pretimeout = reset_time - event_time;
+
+			dev_dbg(eio_wdt->dev,
+				"Pretimeout H/W enabled with event %s of %u secs\n",
+				type_strs[type], eio_wdt->wdd.pretimeout);
+		} else {
+			eio_wdt->wdd.timeout    = event_time;
+			eio_wdt->wdd.pretimeout = 0;
+		}
+
+		eio_wdt->event_type = type;
+
+		dev_dbg(eio_wdt->dev, "Timeout H/W enabled of %u secs\n",
+			eio_wdt->wdd.timeout);
+		return 0;
+	}
+
+	eio_wdt->event_type         = EVENT_NONE;
+	eio_wdt->wdd.pretimeout     = reset_time ? 0 : WATCHDOG_PRETIMEOUT;
+	eio_wdt->wdd.timeout        = reset_time ? reset_time : WATCHDOG_TIMEOUT;
+
+	return 0;
+}
+
+static int set_ctrl(struct eio_wdt_dev *eio_wdt, u8 ctrl)
+{
+	return pmc_write(eio_wdt->mfd, REG_CONTROL, &ctrl);
+}
+
+static int wdt_start(struct watchdog_device *wdd)
+{
+	struct eio_wdt_dev *eio_wdt = watchdog_get_drvdata(wdd);
+	int ret;
+
+	ret = wdt_set_config(eio_wdt);
+	if (ret)
+		return ret;
+
+	ret = set_ctrl(eio_wdt, CTRL_START);
+	if (!ret) {
+		eio_wdt->last_time = jiffies;
+		dev_dbg(eio_wdt->dev, "Watchdog started\n");
+	}
+
+	return ret;
+}
+
+static int wdt_stop(struct watchdog_device *wdd)
+{
+	struct eio_wdt_dev *eio_wdt = watchdog_get_drvdata(wdd);
+	int ret;
+
+	dev_dbg(eio_wdt->dev, "Watchdog stopped\n");
+	eio_wdt->last_time = 0;
+
+	ret = set_ctrl(eio_wdt, CTRL_STOP);
+	return ret;
+}
+
+static int wdt_ping(struct watchdog_device *wdd)
+{
+	struct eio_wdt_dev *eio_wdt = watchdog_get_drvdata(wdd);
+	int ret;
+
+	dev_dbg(eio_wdt->dev, "Watchdog ping\n");
+
+	ret = set_ctrl(eio_wdt, CTRL_TRIGGER);
+	if (!ret)
+		eio_wdt->last_time = jiffies;
+
+	return ret;
+}
+
+static int wdt_support(struct eio_wdt_dev *eio_wdt)
+{
+	u8 support;
+
+	if (pmc_read(eio_wdt->mfd, REG_STATUS, &support))
+		return -EIO;
+
+	if (!(support & SUPPORT_AVAILABLE))
+		return -ENODEV;
+
+	if ((support & SUPPORT_RESET) != SUPPORT_RESET)
+		return -ENODEV;
+
+	eio_wdt->support = support;
+
+	return 0;
+}
+
+static int wdt_get_irq_io(struct eio_wdt_dev *eio_wdt)
+{
+	int ret  = 0;
+	int idx  = EIO_PNP_INDEX;
+	int data = EIO_PNP_DATA;
+	struct regmap *map = eio_wdt->iomap;
+
+	mutex_lock(&eio_wdt->core->mutex);
+
+	/* Unlock EC IO port */
+	ret |= regmap_write(map, idx, IOREG_UNLOCK);
+	ret |= regmap_write(map, idx, IOREG_UNLOCK);
+
+	/* Select logical device to PMC */
+	ret |= regmap_write(map, idx,  IOREG_LDN);
+	ret |= regmap_write(map, data, IOREG_LDN_PMCIO);
+
+	/* Get IRQ number */
+	ret |= regmap_write(map, idx,  IOREG_IRQ);
+	ret |= regmap_read(map, data, &eio_wdt->irq);
+
+	/* Lock back */
+	ret |= regmap_write(map, idx, IOREG_LOCK);
+
+	mutex_unlock(&eio_wdt->core->mutex);
+
+	return ret ? -EIO : 0;
+}
+
+static int wdt_get_irq_pmc(struct eio_wdt_dev *eio_wdt)
+{
+	return pmc_read(eio_wdt->mfd, REG_IRQ_NUMBER, &eio_wdt->irq);
+}
+
+static int wdt_get_irq(struct eio_wdt_dev *eio_wdt)
+{
+	int ret;
+
+	if (!(eio_wdt->support & BIT(EVENT_IRQ)))
+		return -ENODEV;
+
+	ret = wdt_get_irq_pmc(eio_wdt);
+	if (ret) {
+		dev_err(eio_wdt->dev, "Error get irq by pmc\n");
+		return ret;
+	}
+
+	if (eio_wdt->irq)
+		return 0;
+
+	/* Fallback: get IRQ number from EC IO space */
+	ret = wdt_get_irq_io(eio_wdt);
+	if (ret) {
+		dev_err(eio_wdt->dev, "Error get irq by io\n");
+		return ret;
+	}
+
+	if (!eio_wdt->irq) {
+		dev_err(eio_wdt->dev, "Error IRQ number = 0\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int wdt_set_irq_io(struct eio_wdt_dev *eio_wdt)
+{
+	int ret  = 0;
+	int idx  = EIO_PNP_INDEX;
+	int data = EIO_PNP_DATA;
+	struct regmap *map = eio_wdt->iomap;
+
+	mutex_lock(&eio_wdt->core->mutex);
+
+	/* Unlock EC IO port */
+	ret = regmap_write(map, idx, IOREG_UNLOCK);
+	if (ret)
+		goto unlock;
+	ret = regmap_write(map, idx, IOREG_UNLOCK);
+	if (ret)
+		goto unlock;
+
+	/* Select logical device to PMC */
+	ret = regmap_write(map, idx, IOREG_LDN);
+	if (ret)
+		goto unlock;
+	ret = regmap_write(map, data, IOREG_LDN_PMCIO);
+	if (ret)
+		goto unlock;
+
+	/* Enable WDT */
+	ret = regmap_write(map, idx, IOREG_WDT_STATUS);
+	if (ret)
+		goto unlock;
+	ret = regmap_write(map, data, FLAG_WDT_ENABLED);
+	if (ret)
+		goto unlock;
+
+	/* Set IRQ number */
+	ret = regmap_write(map, idx, IOREG_IRQ);
+	if (ret)
+		goto unlock;
+	ret = regmap_write(map, data, eio_wdt->irq);
+	if (ret)
+		goto unlock;
+
+	/* Lock back */
+	ret = regmap_write(map, idx, IOREG_LOCK);
+
+unlock:
+	mutex_unlock(&eio_wdt->core->mutex);
+	return ret;
+}
+
+static int wdt_set_irq_pmc(struct eio_wdt_dev *eio_wdt)
+{
+	return pmc_write(eio_wdt->mfd, REG_IRQ_NUMBER, &eio_wdt->irq);
+}
+
+static int wdt_set_irq(struct eio_wdt_dev *eio_wdt)
+{
+	int ret;
+
+	if (!(eio_wdt->support & BIT(EVENT_IRQ)))
+		return -ENODEV;
+
+	ret = wdt_set_irq_io(eio_wdt);
+	if (ret) {
+		dev_err(eio_wdt->dev, "Error set irq by io\n");
+		return ret;
+	}
+
+	ret = wdt_set_irq_pmc(eio_wdt);
+	if (ret) {
+		dev_err(eio_wdt->dev, "Error set irq by pmc\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int wdt_get_irq_event(struct eio_wdt_dev *eio_wdt)
+{
+	u8 status;
+
+	if (pmc_read(eio_wdt->mfd, REG_EVENT, &status))
+		return 0;
+
+	return status;
+}
+
+static irqreturn_t wdt_isr(int irq, void *arg)
+{
+	return IRQ_WAKE_THREAD;
+}
+
+static irqreturn_t wdt_threaded_isr(int irq, void *arg)
+{
+	struct eio_wdt_dev *eio_wdt = arg;
+	u8 status = wdt_get_irq_event(eio_wdt) & FLAG_TRIGGER_IRQ;
+
+	if (!status)
+		return IRQ_NONE;
+
+	if (eio_wdt->wdd.pretimeout) {
+		watchdog_notify_pretimeout(&eio_wdt->wdd);
+	} else {
+		dev_crit(eio_wdt->dev, "Watchdog expired, rebooting\n");
+		emergency_restart();
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int query_irq(struct eio_wdt_dev *eio_wdt)
+{
+	int ret = 0;
+
+	ret = wdt_get_irq(eio_wdt);
+	if (ret)
+		return ret;
+
+	dev_dbg(eio_wdt->dev, "IRQ = %d\n", eio_wdt->irq);
+
+	return wdt_set_irq(eio_wdt);
+}
+
+static int wdt_init(struct eio_wdt_dev *eio_wdt)
+{
+	int ret;
+
+	ret = wdt_support(eio_wdt);
+	if (ret)
+		return ret;
+
+	ret = wdt_get_config(eio_wdt);
+	if (ret)
+		return ret;
+
+	ret = wdt_get_type(eio_wdt);
+	if (ret)
+		return ret;
+
+	if (eio_wdt->event_type == EVENT_IRQ)
+		ret = query_irq(eio_wdt);
+
+	return ret;
+}
+
+static const struct watchdog_ops wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= wdt_start,
+	.stop		= wdt_stop,
+	.ping		= wdt_ping,
+	.set_timeout	= wdt_set_timeout,
+	.set_pretimeout = wdt_set_pretimeout,
+};
+
+static struct watchdog_info wdinfo = {
+	.identity = KBUILD_MODNAME,
+	.options  = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
+		    WDIOF_PRETIMEOUT | WDIOF_MAGICCLOSE,
+};
+
+static int eio_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct eio_wdt_dev *eio_wdt;
+	struct watchdog_device *wdd;
+	int ret = 0;
+
+	eio_wdt = devm_kzalloc(dev, sizeof(*eio_wdt), GFP_KERNEL);
+	if (!eio_wdt)
+		return -ENOMEM;
+
+	eio_wdt->dev = dev;
+	eio_wdt->mfd = dev->parent;
+	eio_wdt->iomap = dev_get_regmap(dev->parent, NULL);
+	if (!eio_wdt->iomap)
+		return dev_err_probe(dev, -ENODEV, "parent regmap missing\n");
+
+	eio_wdt->core = dev_get_drvdata(dev->parent);
+	if (!eio_wdt->core)
+		return dev_err_probe(dev, -ENODEV, "eio_core not present\n");
+
+	ret = wdt_init(eio_wdt);
+	if (ret) {
+		dev_err(dev, "wdt_init fail\n");
+		return -EIO;
+	}
+
+	if (eio_wdt->event_type == EVENT_IRQ) {
+		ret = devm_request_threaded_irq(dev, eio_wdt->irq,
+						wdt_isr, wdt_threaded_isr,
+						IRQF_SHARED | IRQF_ONESHOT, pdev->name,
+						eio_wdt);
+		if (ret) {
+			dev_err_probe(dev, ret, "IRQ %u request fail: Disabled.\n",
+				eio_wdt->irq);
+			return ret;
+		}
+	}
+
+	wdd = &eio_wdt->wdd;
+	wdd->info        = &wdinfo;
+	wdd->ops         = &wdt_ops;
+	wdd->parent      = dev;
+	wdd->min_timeout = 1;
+	wdd->max_timeout = 0x7FFF;
+
+	if (ret) {
+		dev_err(dev, "Init timeout fail\n");
+		return ret;
+	}
+
+	watchdog_stop_on_reboot(&eio_wdt->wdd);
+	watchdog_stop_on_unregister(&eio_wdt->wdd);
+
+	watchdog_set_drvdata(&eio_wdt->wdd, eio_wdt);
+	platform_set_drvdata(pdev, eio_wdt);
+
+	ret = devm_watchdog_register_device(dev, &eio_wdt->wdd);
+	if (ret)
+		dev_err(dev, "Cannot register watchdog device (err: %d)\n", ret);
+
+	return ret;
+}
+
+static struct platform_driver eio_wdt_driver = {
+	.probe  = eio_wdt_probe,
+	.driver = {
+		.name = "eio_wdt",
+	},
+};
+module_platform_driver(eio_wdt_driver);
+
+MODULE_AUTHOR("Wenkai Chung <[email protected]>");
+MODULE_AUTHOR("Ramiro Oliveira <[email protected]>");
+MODULE_DESCRIPTION("Watchdog interface for Advantech EIO embedded controller");
+MODULE_LICENSE("GPL");

-- 
2.43.0