@@ -616,6 +616,7 @@ F:	drivers/gpio/gpio-eio.c
 F:	drivers/hwmon/eio-hwmon.c
 F:	drivers/i2c/busses/i2c-eio.c
 F:	drivers/mfd/eio_core.c
+F:	drivers/thermal/eio_fan.c
 F:	drivers/thermal/eio_thermal.c
 F:	drivers/video/backlight/eio_bl.c
 F:	drivers/watchdog/eio_wdt.c

@@ -436,6 +436,14 @@ config EIO_THERMAL
 	  the Linux thermal framework. It communicates with the EC through the
 	  EIO MFD core.
 
+config EIO_FAN
+        tristate "Advantech EIO Fan cooling device"
+        depends on MFD_EIO && THERMAL
+        help
+          Fan cooling device for the Advantech EIO. This driver exposes a
+          thermal cooling device with controllable states (e.g. Auto/Manual/PWM).
+          It communicates with the EC through the EIO MFD core.
+
 menu "Mediatek thermal drivers"
 depends on ARCH_MEDIATEK || COMPILE_TEST
 source "drivers/thermal/mediatek/Kconfig"

@@ -55,6 +55,7 @@ obj-$(CONFIG_IMX91_THERMAL)	+= imx91_thermal.o
 obj-$(CONFIG_MAX77620_THERMAL)	+= max77620_thermal.o
 obj-$(CONFIG_QORIQ_THERMAL)	+= qoriq_thermal.o
 obj-$(CONFIG_DA9062_THERMAL)	+= da9062-thermal.o
+obj-$(CONFIG_EIO_FAN)		+= eio_fan.o
 obj-$(CONFIG_EIO_THERMAL)	+= eio_thermal.o
 obj-y				+= intel/
 obj-$(CONFIG_TI_SOC_THERMAL)	+= ti-soc-thermal/

@@ -0,0 +1,478 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * eio_fan
+ * ============
+ * Thermal zone driver for Advantech EIO embedded controller's smart
+ * fan mechanism.
+ *
+ * We create a sysfs 'name' of the zone, point out where the fan is. Such as
+ * CPU0, SYS3, etc.
+ *
+ * The sysfs 'fan_mode' can be one of 'Stop', 'Full', 'Manual' or 'Auto'.
+ * If 'Manual'. You can control fan speed via sysfs 'PWM'.
+ * If it is 'Auto'. It enables the smart fan mechanism as below.
+ *
+ * In EIO chip. The smart fan has 3 trips. When the temperature is:
+ * - Over Temp High(trip0), the Fan runs at the fan PWM High.
+ * - Between Temp Low and Temp High(trip1 - trip0), the fan PWM value slopes
+ *   from PWM Low to PWM High.
+ * - Between Temp Stop and Temp Low(trip2 - trip1), the fan PWM is PWM low.
+ * - Below Temp Stop, the fan stopped.
+ *
+ * (PWM)|
+ *	|
+ * High |............................. ______________
+ * (Max)|			      /:
+ *	|			     / :
+ *	|			    /  :
+ *	|			   /   :
+ *	|			  /    :
+ *	|			 /     :
+ *	|			/      :
+ *	|		       /       :
+ *  Low	|.......... __________/	       :
+ *	|	    |	      :	       :
+ *	|	    |	      :	       :
+ *    0	+===========+---------+--------+-------------
+ *	0	   Stop	     Low      High	(Temp)
+ *
+ * Copyright (C) 2025 Advantech Corporation. All rights reserved.
+ */
+
+#include <linux/ctype.h>
+#include <linux/errno.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/eio.h>
+#include <linux/minmax.h>
+#include <linux/module.h>
+#include <linux/sysfs.h>
+#include <linux/thermal.h>
+
+#define CMD_FAN_WRITE		0x24
+#define CMD_FAN_READ		0x25
+#define FAN_MAX			0x04
+
+#define CMD_THERM_WRITE		0x10
+#define CMD_THERM_READ		0x11
+#define THERM_MAX		0x04
+#define THERM_MULTI		100
+
+#define CTRL_STATE		0x00
+#define CTRL_TYPE		0x01
+#define CTRL_CTRL		0x02
+#define CTRL_ERROR		0x04
+#define CTRL_VALUE		0x10
+#define CTRL_INVERT		0x11
+#define CTRL_FREQ		0x12
+#define CTRL_THERM_HIGH		0x13
+#define CTRL_THERM_LOW		0x14
+#define CTRL_THERM_STOP		0x15
+#define CTRL_PWM_HIGH		0x16
+#define CTRL_PWM_LOW		0x17
+#define CTRL_THERM_SRC		0x20
+
+#define CTRLMODE_STOP		0x00
+#define CTRLMODE_FULL		0x01
+#define CTRLMODE_MANUAL		0x02
+#define CTRLMODE_AUTO		0x03
+
+#define DUTY_MAX		100
+#define UNIT_PER_TEMP		10
+#define NAME_SIZE		4
+
+#define TRIP_HIGH		0
+#define TRIP_LOW		1
+#define TRIP_STOP		2
+#define TRIP_NUM		3
+
+/* Bitfields inside CTRL_CTRL */
+#define FAN_MODE_MASK           GENMASK(1, 0)
+#define FAN_SCM_BIT             BIT(2)
+#define FAN_FRAME_BIT           BIT(3)
+#define FAN_SRC_MASK            GENMASK(7, 4)
+
+#define FAN_SRC(val)            (((int)(val)) >> 4)
+
+#ifndef DECI_KELVIN_TO_MILLI_CELSIUS
+#define DECI_KELVIN_TO_MILLI_CELSIUS(t)  ((((t) - 2731) * 100))
+#endif
+
+#ifndef MILLI_CELSIUS_TO_DECI_KELVIN
+#define MILLI_CELSIUS_TO_DECI_KELVIN(t)  ((((t) / 100) + 2731))
+#endif
+
+static const u8 pmc_len[CTRL_THERM_SRC + 1] = {
+/*      0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f */
+	1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	1, 1, 4, 2, 2, 2, 1, 1, 2, 2, 2, 0, 0, 0, 0, 0,
+	1,
+};
+
+static const char fan_name[0x20][NAME_SIZE + 1] = {
+	"CPU0", "CPU1", "CPU2", "CPU3", "SYS0", "SYS1", "SYS2", "SYS3",
+	"", "", "", "", "", "", "", "",
+	"", "", "", "", "", "", "", "",
+	"", "", "", "", "OEM0", "OEM1", "OEM2", "OEM3",
+};
+
+struct eio_fan_trip {
+	u8 trip_ctl;
+};
+
+struct eio_fan_dev {
+	struct device *mfd;
+	struct device *dev;
+	u8 id;
+	struct thermal_zone_device *tzd;
+	struct eio_fan_trip trip_priv[TRIP_NUM];
+};
+
+static int pmc_write(struct device *mfd, u8 ctrl, u8 id, void *data)
+{
+	if (ctrl >= ARRAY_SIZE(pmc_len))
+		return -EINVAL;
+
+	struct pmc_op op = {
+		.cmd       = CMD_FAN_WRITE,
+		.control   = ctrl,
+		.device_id = id,
+		.size	   = pmc_len[ctrl],
+		.payload   = (u8 *)data,
+	};
+	return eio_core_pmc_operation(mfd, &op);
+}
+
+static int pmc_read(struct device *mfd, u8 ctrl, u8 id, void *data)
+{
+	struct pmc_op op = {
+		.cmd       = CMD_FAN_READ,
+		.control   = ctrl,
+		.device_id = id,
+		.size	   = pmc_len[ctrl],
+		.payload   = (u8 *)data,
+	};
+	return eio_core_pmc_operation(mfd, &op);
+}
+
+static int pmc_read_therm(struct device *mfd, u8 ctrl, u8 id, void *data)
+{
+	struct pmc_op op = {
+		.cmd       = CMD_THERM_READ,
+		.control   = ctrl,
+		.device_id = id,
+		.size	   = 2,
+		.payload   = (u8 *)data,
+	};
+	return eio_core_pmc_operation(mfd, &op);
+}
+
+static int eio_fan_get_temp(struct thermal_zone_device *tzd, int *temp)
+{
+	struct eio_fan_dev *fan = thermal_zone_device_priv(tzd);
+	struct device *mfd = fan->mfd;
+	u8 ch = fan->id;
+	int sensor = 0;
+	u16 val = 0;
+	int ret;
+
+	ret = pmc_read(mfd, CTRL_CTRL, ch, &sensor);
+	if (ret)
+		return ret;
+
+	ret = pmc_read_therm(mfd, CTRL_VALUE, (u8)FAN_SRC(sensor), &val);
+	if (ret)
+		return ret;
+
+	*temp = DECI_KELVIN_TO_MILLI_CELSIUS(val);
+	return 0;
+}
+
+static int eio_fan_set_trip_temp(struct thermal_zone_device *tzd,
+				 const struct thermal_trip *trip, int temp)
+{
+	struct eio_fan_dev *fan = thermal_zone_device_priv(tzd);
+	const struct eio_fan_trip *fan_trip = trip->priv;
+	u8 ctl = CTRL_THERM_HIGH + fan_trip->trip_ctl;
+	u16 val;
+
+	if (temp < 1000)
+		return -EINVAL;
+
+	val = MILLI_CELSIUS_TO_DECI_KELVIN(temp);
+	return pmc_write(fan->mfd, ctl, fan->id, &val);
+}
+
+static bool eio_fan_should_bind(struct thermal_zone_device *tzd,
+				const struct thermal_trip *trip,
+				struct thermal_cooling_device *cdev,
+				struct cooling_spec *spec)
+{
+	struct eio_fan_dev *tz_fan  = thermal_zone_device_priv(tzd);
+	struct eio_fan_dev *cd_fan  = cdev->devdata;
+
+	if (!tz_fan || !cd_fan)
+		return false;
+
+	if (tz_fan->mfd != cd_fan->mfd || tz_fan->id != cd_fan->id)
+		return false;
+
+	return true;
+}
+
+static const struct thermal_zone_device_ops zone_ops = {
+	.get_temp = eio_fan_get_temp,
+	.set_trip_temp = eio_fan_set_trip_temp,
+	.should_bind   = eio_fan_should_bind,
+};
+
+static int eio_fan_get_max_state(struct thermal_cooling_device *cdev,
+				 unsigned long *state)
+{
+	*state = 100;
+	return 0;
+}
+
+static int eio_fan_get_cur_state(struct thermal_cooling_device *cdev,
+				 unsigned long *state)
+{
+	struct eio_fan_dev *fan = cdev->devdata;
+	int fan_mode = 0;
+	u8 duty = 0;
+	int ret = 0;
+
+	*state = 0;
+	ret = pmc_read(fan->mfd, CTRL_CTRL, fan->id, &fan_mode);
+	if (ret)
+		return ret;
+
+	switch (fan_mode & FAN_MODE_MASK) {
+	case CTRLMODE_STOP:
+		*state = 0;
+		break;
+	case CTRLMODE_FULL:
+		*state = 100;
+		break;
+	case CTRLMODE_AUTO:
+		*state = 0;
+		ret = 0;
+		break;
+	case CTRLMODE_MANUAL:
+		ret = pmc_read(fan->mfd, CTRL_VALUE, fan->id, &duty);
+		if (ret)
+			return ret;
+		duty = (u8)clamp_val(duty, 0, 100);
+		*state = duty;
+		break;
+	default:
+		*state = 0;
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int eio_fan_set_cur_state(struct thermal_cooling_device *cdev,
+				 unsigned long state)
+{
+	struct eio_fan_dev *fan = cdev->devdata;
+	u8 ctrl = 0;
+	u8 duty;
+	int ret;
+
+	ret = pmc_read(fan->mfd, CTRL_CTRL, fan->id, &ctrl);
+	if (ret)
+		return ret;
+
+	if ((ctrl & FAN_MODE_MASK) != CTRLMODE_MANUAL)
+		return -EOPNOTSUPP;
+
+	duty = (u8)clamp_val(state, 0, 100);
+
+	ret = pmc_write(fan->mfd, CTRL_VALUE, fan->id, &duty);
+
+	return ret;
+}
+
+static const struct thermal_cooling_device_ops cooling_ops = {
+	.get_max_state = eio_fan_get_max_state,
+	.get_cur_state = eio_fan_get_cur_state,
+	.set_cur_state = eio_fan_set_cur_state,
+};
+
+static ssize_t fan_mode_show(struct device *dev, struct device_attribute *attr,
+			     char *buf)
+{
+	static const char * const names[] = { "Stop", "Full", "Manual", "Auto" };
+	struct thermal_zone_device *tzd = dev_get_drvdata(dev);
+	struct eio_fan_dev *fan = thermal_zone_device_priv(tzd);
+	u8 mode = 0;
+
+	int ret = pmc_read(fan->mfd, CTRL_CTRL, fan->id, &mode);
+
+	if (ret)
+		return ret;
+
+	return sysfs_emit(buf, "%s\n", names[mode & 0x03]);
+}
+
+static ssize_t fan_mode_store(struct device *dev, struct device_attribute *attr,
+			      const char *buf, size_t count)
+{
+	static const char * const names[] = { "Stop", "Full", "Manual", "Auto" };
+	struct thermal_zone_device *tzd = dev_get_drvdata(dev);
+	struct eio_fan_dev *fan = thermal_zone_device_priv(tzd);
+	u8 ctrl, newc;
+	int mode_idx, ret;
+
+	for (mode_idx = 0; mode_idx < ARRAY_SIZE(names); mode_idx++) {
+		if (strncasecmp(buf, names[mode_idx], strlen(names[mode_idx])))
+			continue;
+
+		ret = pmc_read(fan->mfd, CTRL_CTRL, fan->id, &ctrl);
+		if (ret)
+			return -EIO;
+
+		newc  = ctrl & FAN_SRC_MASK;
+
+		switch (mode_idx) {
+		case CTRLMODE_AUTO:
+			newc |= FAN_FRAME_BIT;
+			newc &= ~FAN_SCM_BIT;
+			newc |= CTRLMODE_AUTO;
+			break;
+		case CTRLMODE_MANUAL:
+			newc &= ~FAN_FRAME_BIT;
+			newc &= ~FAN_SCM_BIT;
+			newc |= CTRLMODE_MANUAL;
+			break;
+		case CTRLMODE_FULL:
+			newc &= ~FAN_FRAME_BIT;
+			newc &= ~FAN_SCM_BIT;
+			newc |= CTRLMODE_FULL;
+			break;
+		case CTRLMODE_STOP:
+		default:
+			newc &= ~FAN_FRAME_BIT;
+			newc &= ~FAN_SCM_BIT;
+			newc |= CTRLMODE_STOP;
+			break;
+		}
+
+		ret = pmc_write(fan->mfd, CTRL_CTRL, fan->id, &newc);
+		return ret ? ret : count;
+	}
+
+	return -EINVAL;
+}
+
+static DEVICE_ATTR_RW(fan_mode);
+
+static int eio_fan_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	unsigned int fan_id;
+	int ret;
+
+	if (!dev_get_drvdata(dev->parent)) {
+		dev_err(dev, "eio_core not present\n");
+		return -ENODEV;
+	}
+
+	for (fan_id = 0; fan_id < FAN_MAX; fan_id++) {
+		u8 state = 0, name = 0;
+		int trip_hi = 0, trip_lo = 0, trip_stop = 0;
+		int pwm_hi = 0, pwm_lo = 0;
+		struct eio_fan_dev *fan;
+		struct thermal_zone_device *tzd;
+		struct thermal_cooling_device *cdev;
+
+		if (pmc_read(dev->parent, CTRL_STATE, fan_id, &state) ||
+		    pmc_read(dev->parent, CTRL_TYPE, fan_id, &name) ||
+		    pmc_read(dev->parent, CTRL_THERM_HIGH, fan_id, &trip_hi) ||
+		    pmc_read(dev->parent, CTRL_THERM_LOW, fan_id, &trip_lo) ||
+		    pmc_read(dev->parent, CTRL_THERM_STOP, fan_id, &trip_stop) ||
+		    pmc_read(dev->parent, CTRL_PWM_HIGH, fan_id, &pwm_hi) ||
+		    pmc_read(dev->parent, CTRL_PWM_LOW, fan_id, &pwm_lo)) {
+			dev_info(dev, "fan%u: pmc read error, skipping\n", fan_id);
+			continue;
+		}
+
+		if (!(state & 0x1)) {
+			dev_info(dev, "fan%u: firmware reports disabled\n", fan_id);
+			continue;
+		}
+
+		if (!fan_name[name][0]) {
+			dev_info(dev, "fan%u: unknown name index %u\n", fan_id, name);
+			continue;
+		}
+
+		fan = devm_kzalloc(dev, sizeof(*fan), GFP_KERNEL);
+		if (!fan)
+			return -ENOMEM;
+
+		fan->mfd = dev->parent;
+		fan->id  = (u8)fan_id;
+
+		fan->trip_priv[TRIP_HIGH].trip_ctl = CTRL_THERM_HIGH;
+		fan->trip_priv[TRIP_LOW].trip_ctl  = CTRL_THERM_LOW;
+		fan->trip_priv[TRIP_STOP].trip_ctl = CTRL_THERM_STOP;
+
+		struct thermal_trip trips[TRIP_NUM] = {
+			[TRIP_HIGH] = {
+				.type = THERMAL_TRIP_ACTIVE,
+				.temperature = DECI_KELVIN_TO_MILLI_CELSIUS(trip_hi),
+				.flags = THERMAL_TRIP_FLAG_RW_TEMP,
+				.priv = &fan->trip_priv[TRIP_HIGH],
+			},
+			[TRIP_LOW] = {
+				.type = THERMAL_TRIP_ACTIVE,
+				.temperature = DECI_KELVIN_TO_MILLI_CELSIUS(trip_lo),
+				.flags = THERMAL_TRIP_FLAG_RW_TEMP,
+				.priv = &fan->trip_priv[TRIP_LOW],
+			},
+			[TRIP_STOP] = {
+				.type = THERMAL_TRIP_ACTIVE,
+				.temperature = DECI_KELVIN_TO_MILLI_CELSIUS(trip_stop),
+				.flags = THERMAL_TRIP_FLAG_RW_TEMP,
+				.priv = &fan->trip_priv[TRIP_STOP],
+			},
+		};
+
+		tzd = thermal_zone_device_register_with_trips(fan_name[name],
+							      trips, TRIP_NUM,
+							      fan,
+							      &zone_ops,
+							      NULL,
+							      0, 0);
+		if (IS_ERR(tzd))
+			return PTR_ERR(tzd);
+
+		cdev = thermal_cooling_device_register(fan_name[name], fan, &cooling_ops);
+		if (IS_ERR(cdev)) {
+			thermal_zone_device_unregister(tzd);
+			dev_err(dev, "fan%u: cdev register failed: %ld\n",
+				fan_id, PTR_ERR(cdev));
+			return PTR_ERR(cdev);
+		}
+
+		dev_set_drvdata(thermal_zone_device(tzd), tzd);
+		ret = device_create_file(thermal_zone_device(tzd), &dev_attr_fan_mode);
+		if (ret)
+			dev_warn(dev, "Error create thermal zone fan_mode sysfs\n");
+	}
+	return 0;
+}
+
+static struct platform_driver eio_fan_driver = {
+	.probe  = eio_fan_probe,
+	.driver = {
+		.name = "eio_fan",
+	},
+};
+
+module_platform_driver(eio_fan_driver);
+
+MODULE_AUTHOR("Wenkai Chung <wenkai.chung@advantech.com.tw>");
+MODULE_AUTHOR("Ramiro Oliveira <ramiro.oliveira@advantech.com>");
+MODULE_DESCRIPTION("Fan driver for Advantech EIO embedded controller");
+MODULE_LICENSE("GPL");