Add support for EMC2305 Fan Speed Controller.

From: Michael Shych <[email protected]>

Introduce platform data structure for EM2305 driver to allow configuration device PWMs and thermal zones by passing required platform data to the driver. If no platform data is provided, the driver is supposed to work with default settings.

Signed-off-by Michael Shych <[email protected]>

Reviewed-by Vadim Pasternak <[email protected]>

---
 include/linux/platform_data/emc2305.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 include/linux/platform_data/emc2305.h

include/linux/platform_data/emc2305.h new file +22 -0

new file mode 100644
index 000000000000..54d672dd6f7d
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __LINUX_PLATFORM_DATA_EMC2305__
+#define __LINUX_PLATFORM_DATA_EMC2305__
+
+#define EMC2305_PWM_MAX	5
+
+/**
+ * struct emc2305_platform_data - EMC2305 driver platform data
+ * @max_state: maximum cooling state of the cooling device;
+ * @pwm_num: number of active channels;
+ * @pwm_separate: separate PWM settings for every channel;
+ * @pwm_min: array of minimum PWM per channel;
+ */
+struct emc2305_platform_data {
+	u8 max_state;
+	u8 pwm_num;
+	bool pwm_separate;
+	u8 pwm_min[EMC2305_PWM_MAX];
+};
+
+#endif

From: Michael Shych <[email protected]>

Add driver for Microchip EMC2301/2/3/5 RPM-based PWM Fan Speed Controller. Modify Makefile and Kconfig to support Microchip EMC2305 RPM-based PWM Fan Speed Controller.

Signed-off-by Michael Shych <[email protected]>

Reviewed-by Vadim Pasternak <[email protected]>

---
v4->v5
Changes added by Michael Shych:
- Remove OF interface;
- Add optional way to pass info to the driver through platform data;
- Fix 0 RPM report.
v3->v4
Changes pointed out by Guenter Roeck:
- Add error check in functions returns;
- Typo fix;
- Change error code in return;
- Change if case.
v2->v3
Change pointed out by Guenter Roeck:
- Change casting from const pointer;
- Remove pwm_max per channel parameter.
Changes added by Michael Shych:
- Add pwm_separate field instead using of a special case of pwm_channel;
- Change the mechanism of obtaining a number of pwm channels. v1->v2
Changes pointed out by Guenter Roeck:
- Remove unnecessary include;
- Standard multi-line comments form;
- Defines indentation;
- Remove unnecessary returns;
- Add validation of received dt parameters;
- Remove unnecessary brackets;
Changes added by Michael Shych:
- Fix initial PWM settings;
- Change PWM write in case of common PWM channel;
- Separate pwm-min, pwm-max per PWM channel.

---
 drivers/hwmon/Kconfig   |  13 +
 drivers/hwmon/Makefile  |   1 +
 drivers/hwmon/emc2305.c | 624 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 638 insertions(+)
 create mode 100644 drivers/hwmon/emc2305.c

drivers/hwmon/Kconfig +13 -0

index e70d9614bec2..1ebc8e6c86f1 100644
@@ -1785,6 +1785,19 @@ config SENSORS_EMC2103
 	  This driver can also be built as a module. If so, the module
 	  will be called emc2103.
 
+config SENSORS_EMC2305
+	tristate "Microchip EMC2305 and compatible EMC2301/2/3"
+	depends on I2C
+	imply THERMAL
+	help
+	  If you say yes here you get support for the Microchip EMC2305
+	  fan controller chips.
+	  The Microchip EMC2305 is a fan controller for up to 5 fans.
+	  Fan rotation speeds are reported in RPM.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called emc2305.
+
 config SENSORS_EMC6W201
 	tristate "SMSC EMC6W201"
 	depends on I2C

drivers/hwmon/Makefile +1 -0

index 007e829d1d0d..7706557dfa86 100644
@@ -70,6 +70,7 @@ obj-$(CONFIG_SENSORS_DS620)	+= ds620.o
 obj-$(CONFIG_SENSORS_DS1621)	+= ds1621.o
 obj-$(CONFIG_SENSORS_EMC1403)	+= emc1403.o
 obj-$(CONFIG_SENSORS_EMC2103)	+= emc2103.o
+obj-$(CONFIG_SENSORS_EMC2305)	+= emc2305.o
 obj-$(CONFIG_SENSORS_EMC6W201)	+= emc6w201.o
 obj-$(CONFIG_SENSORS_F71805F)	+= f71805f.o
 obj-$(CONFIG_SENSORS_F71882FG)	+= f71882fg.o

drivers/hwmon/emc2305.c new file +25 -0

new file mode 100644
index 000000000000..86b410b38ff7
@@ -0,0 +1,624 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Hardware monitoring driver for EMC2305 fan controller
+ *
+ * Copyright (C) 2022 Nvidia Technologies Ltd.
+ */
+
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/platform_data/emc2305.h>
+#include <linux/thermal.h>
+#include <linux/version.h>
+
+static const unsigned short
+emc2305_normal_i2c[] = { 0x27, 0x2c, 0x2d, 0x2e, 0x2f, 0x4c, 0x4d, I2C_CLIENT_END };
+
+#define EMC2305_REG_DRIVE_FAIL_STATUS	0x27
+#define EMC2305_REG_DEVICE		0xfd
+#define EMC2305_REG_VENDOR		0xfe
+#define EMC2305_FAN_MAX			0xff
+#define EMC2305_FAN_MIN			0x00
+#define EMC2305_FAN_MAX_STATE		10
+#define EMC2305_DEVICE			0x34

drivers/hwmon/emc2305.c new file +589 -0

+
+/*
+ * Factor by equations [2] and [3] from data sheet; valid for fans where the number of edges
+ * equal (poles * 2 + 1).
+ */
+#define EMC2305_RPM_FACTOR		3932160
+
+#define EMC2305_REG_FAN_DRIVE(n)	(0x30 + 0x10 * (n))
+#define EMC2305_REG_FAN_MIN_DRIVE(n)	(0x38 + 0x10 * (n))
+#define EMC2305_REG_FAN_TACH(n)		(0x3e + 0x10 * (n))
+
+enum emc230x_product_id {
+	EMC2305 = 0x34,
+	EMC2303 = 0x35,
+	EMC2302 = 0x36,
+	EMC2301 = 0x37,
+};
+
+static const struct i2c_device_id emc2305_ids[] = {
+	{ "emc2305", 0 },
+	{ "emc2303", 0 },
+	{ "emc2302", 0 },
+	{ "emc2301", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, emc2305_ids);
+
+/**
+ * @cdev: cooling device;
+ * @curr_state: cooling current state;
+ * @last_hwmon_state: last cooling state updated by hwmon subsystem;
+ * @last_thermal_state: last cooling state updated by thermal subsystem;
+ *
+ * The 'last_hwmon_state' and 'last_thermal_state' fields are provided to support fan low limit
+ * speed feature. The purpose of this feature is to provides ability to limit fan speed
+ * according to some system wise considerations, like absence of some replaceable units (PSU or
+ * line cards), high system ambient temperature, unreliable transceivers temperature sensing or
+ * some other factors which indirectly impacts system's airflow
+ * Fan low limit feature is supported through 'hwmon' interface: 'hwmon' 'pwm' attribute is
+ * used for setting low limit for fan speed in case 'thermal' subsystem is configured in
+ * kernel. In this case setting fan speed through 'hwmon' will never let the 'thermal'
+ * subsystem to select a lower duty cycle than the duty cycle selected with the 'pwm'
+ * attribute.
+ * From other side, fan speed is to be updated in hardware through 'pwm' only in case the
+ * requested fan speed is above last speed set by 'thermal' subsystem, otherwise requested fan
+ * speed will be just stored with no PWM update.
+ */
+struct emc2305_cdev_data {
+	struct thermal_cooling_device *cdev;
+	unsigned int cur_state;
+	unsigned long last_hwmon_state;
+	unsigned long last_thermal_state;
+};
+
+/**
+ * @client: i2c client;
+ * @hwmon_dev: hwmon device;
+ * @max_state: maximum cooling state of the cooling device;
+ * @pwm_num: number of PWM channels;
+ * @pwm_separate: separate PWM settings for every channel;
+ * @pwm_min: array of minimum PWM per channel;
+ * @cdev_data: array of cooling devices data;
+ */
+struct emc2305_data {
+	struct i2c_client *client;
+	struct device *hwmon_dev;
+	u8 max_state;
+	u8 pwm_num;
+	bool pwm_separate;
+	u8 pwm_min[EMC2305_PWM_MAX];
+	struct emc2305_cdev_data cdev_data[EMC2305_PWM_MAX];
+};
+
+static char *emc2305_fan_name[] = {
+	"emc2305_fan",
+	"emc2305_fan1",
+	"emc2305_fan2",
+	"emc2305_fan3",
+	"emc2305_fan4",
+	"emc2305_fan5",
+};
+
+static void emc2305_unset_tz(struct device *dev);
+
+static int emc2305_get_max_channel(const struct emc2305_data *data)
+{
+	return data->pwm_num;
+}
+
+static int emc2305_get_cdev_idx(struct thermal_cooling_device *cdev)
+{
+	struct emc2305_data *data = cdev->devdata;
+	size_t len = strlen(cdev->type);
+	int ret;
+
+	if (len <= 0)
+		return -EINVAL;
+
+	/*
+	 * Returns index of cooling device 0..4 in case of separate PWM setting.
+	 * Zero index is used in case of one common PWM setting.
+	 * If the mode is not set as pwm_separate, all PWMs are to be bound
+	 * to the common thermal zone and should work at the same speed
+	 * to perform cooling for the same thermal junction.
+	 * Otherwise, return specific channel that will be used in bound
+	 * related PWM to the thermal zone.
+	 */
+	if (!data->pwm_separate)
+		return 0;
+
+	ret = cdev->type[len - 1];
+	switch (ret) {
+	case '1' ... '5':
+		return ret - '1';
+	default:
+		break;
+	}
+	return -EINVAL;
+}
+
+static int emc2305_get_cur_state(struct thermal_cooling_device *cdev, unsigned long *state)
+{
+	int cdev_idx;
+	struct emc2305_data *data = cdev->devdata;
+
+	cdev_idx = emc2305_get_cdev_idx(cdev);
+	if (cdev_idx < 0)
+		return cdev_idx;
+
+	*state = data->cdev_data[cdev_idx].cur_state;
+	return 0;
+}
+
+static int emc2305_get_max_state(struct thermal_cooling_device *cdev, unsigned long *state)
+{
+	struct emc2305_data *data = cdev->devdata;
+	*state = data->max_state;
+	return 0;
+}
+
+static int emc2305_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
+{
+	int cdev_idx, ret;
+	struct emc2305_data *data = cdev->devdata;
+	struct i2c_client *client = data->client;
+	u8 val, i;
+
+	if (state > data->max_state)
+		return -EINVAL;
+
+	cdev_idx =  emc2305_get_cdev_idx(cdev);
+	if (cdev_idx < 0)
+		return cdev_idx;
+
+	/* Save thermal state. */
+	data->cdev_data[cdev_idx].last_thermal_state = state;
+	state = max_t(unsigned long, state, data->cdev_data[cdev_idx].last_hwmon_state);
+
+	val = EMC2305_PWM_STATE2DUTY(state, data->max_state, EMC2305_FAN_MAX);
+	if (val > EMC2305_FAN_MAX)
+		return -EINVAL;
+
+	data->cdev_data[cdev_idx].cur_state = state;
+	if (data->pwm_separate) {
+		ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_DRIVE(cdev_idx), val);
+		if (ret < 0)
+			return ret;
+	} else {
+		/*
+		 * Set the same PWM value in all channels
+		 * if common PWM channel is used.
+		 */
+		for (i = 0; i < data->pwm_num; i++) {
+			ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_DRIVE(i), val);
+			if (ret < 0)
+				return ret;
+		}
+	}
+
+	return 0;
+}
+
+static const struct thermal_cooling_device_ops emc2305_cooling_ops = {
+	.get_max_state = emc2305_get_max_state,
+	.get_cur_state = emc2305_get_cur_state,
+	.set_cur_state = emc2305_set_cur_state,
+};
+
+static int emc2305_show_fault(struct device *dev, int channel)
+{
+	struct emc2305_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	int status_reg;
+
+	status_reg = i2c_smbus_read_byte_data(client, EMC2305_REG_DRIVE_FAIL_STATUS);
+	if (status_reg < 0)
+		return status_reg;
+
+	return status_reg & (1 << channel) ? 1 : 0;
+}
+
+static int emc2305_show_fan(struct device *dev, int channel)
+{
+	struct emc2305_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	int ret;
+
+	ret = i2c_smbus_read_word_swapped(client, EMC2305_REG_FAN_TACH(channel));
+	if (ret <= 0)
+		return ret;
+
+	ret = ret >> EMC2305_TACH_REGS_UNUSE_BITS;
+	ret = EMC2305_RPM_FACTOR / ret;
+	if (ret <= EMC2305_TACH_RANGE_MIN)
+		return 0;
+
+	return ret * EMC2305_TACH_CNT_MULTIPLIER;
+}
+
+static int emc2305_show_pwm(struct device *dev, int channel)
+{
+	struct emc2305_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+
+	return i2c_smbus_read_byte_data(client, EMC2305_REG_FAN_DRIVE(channel));
+}
+
+static int emc2305_set_pwm(struct device *dev, long val, int channel)
+{
+	struct emc2305_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	int ret;
+
+	if (val < data->pwm_min[channel] || val > EMC2305_FAN_MAX)
+		return -EINVAL;
+
+	ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_DRIVE(channel), val);
+	if (ret < 0)
+		return ret;
+	data->cdev_data[channel].cur_state = EMC2305_PWM_DUTY2STATE(val, data->max_state,
+								    EMC2305_FAN_MAX);
+	return 0;
+}
+
+static int emc2305_set_single_tz(struct device *dev, int idx)
+{
+	struct emc2305_data *data = dev_get_drvdata(dev);
+	long pwm;
+	int i, cdev_idx, ret;
+
+	cdev_idx = (idx) ? idx - 1 : 0;
+	pwm = data->pwm_min[cdev_idx];
+
+	data->cdev_data[cdev_idx].cdev =
+		thermal_cooling_device_register(emc2305_fan_name[idx], data,
+						&emc2305_cooling_ops);
+
+	if (IS_ERR(data->cdev_data[cdev_idx].cdev)) {
+		dev_err(dev, "Failed to register cooling device %s\n", emc2305_fan_name[idx]);
+		return PTR_ERR(data->cdev_data[cdev_idx].cdev);
+	}
+	/* Set minimal PWM speed. */
+	if (data->pwm_separate) {
+		ret = emc2305_set_pwm(dev, pwm, cdev_idx);
+		if (ret < 0)
+			return ret;
+	} else {
+		for (i = 0; i < data->pwm_num; i++) {
+			ret = emc2305_set_pwm(dev, pwm, i);
+			if (ret < 0)
+				return ret;
+		}
+	}
+	data->cdev_data[cdev_idx].cur_state =
+		EMC2305_PWM_DUTY2STATE(data->pwm_min[cdev_idx], data->max_state,
+				       EMC2305_FAN_MAX);
+	data->cdev_data[cdev_idx].last_hwmon_state =
+		EMC2305_PWM_DUTY2STATE(data->pwm_min[cdev_idx], data->max_state,
+				       EMC2305_FAN_MAX);
+	return 0;
+}
+
+static int emc2305_set_tz(struct device *dev)
+{
+	struct emc2305_data *data = dev_get_drvdata(dev);
+	int i, ret;
+
+	if (!data->pwm_separate)
+		return emc2305_set_single_tz(dev, 0);
+
+	for (i = 0; i < data->pwm_num; i++) {
+		ret = emc2305_set_single_tz(dev, i + 1);
+		if (ret)
+			goto thermal_cooling_device_register_fail;
+	}
+	return 0;
+
+thermal_cooling_device_register_fail:
+	emc2305_unset_tz(dev);
+	return ret;
+}
+
+static void emc2305_unset_tz(struct device *dev)
+{
+	struct emc2305_data *data = dev_get_drvdata(dev);
+	int i;
+
+	/* Unregister cooling device. */
+	for (i = 0; i < EMC2305_PWM_MAX; i++)
+		if (data->cdev_data[i].cdev)
+			thermal_cooling_device_unregister(data->cdev_data[i].cdev);
+}
+
+static umode_t
+emc2305_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr, int channel)
+{
+	int max_channel = emc2305_get_max_channel(data);
+
+	/* Don't show channels which are not physically connected. */
+	if (channel >= max_channel)
+		return 0;
+	switch (type) {
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_input:
+			return 0444;
+		case hwmon_fan_fault:
+			return 0444;
+		default:
+			break;
+		}
+		break;
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_input:
+			return 0644;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+};
+
+static int
+emc2305_write(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long val)
+{
+	struct emc2305_data *data = dev_get_drvdata(dev);
+	int cdev_idx;
+
+	switch (type) {
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_input:
+			/* If thermal is configured - handle PWM limit setting. */
+			if (IS_REACHABLE(CONFIG_THERMAL)) {
+				if (data->pwm_separate)
+					cdev_idx = channel;
+				else
+					cdev_idx = 0;
+				data->cdev_data[cdev_idx].last_hwmon_state =
+					EMC2305_PWM_DUTY2STATE(val, data->max_state,
+							       EMC2305_FAN_MAX);
+				/*
+				 * Update PWM only in case requested state is not less than the
+				 * last thermal state.
+				 */
+				if (data->cdev_data[cdev_idx].last_hwmon_state >=
+				    data->cdev_data[cdev_idx].last_thermal_state)
+					return emc2305_set_cur_state(data->cdev_data[cdev_idx].cdev,
+							data->cdev_data[cdev_idx].last_hwmon_state);
+				return 0;
+			}
+			return emc2305_set_pwm(dev, val, channel);
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return -EOPNOTSUPP;
+};
+
+static int
+emc2305_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long *val)
+{
+	int ret;
+
+	switch (type) {
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_input:
+			ret = emc2305_show_fan(dev, channel);
+			if (ret < 0)
+				return ret;
+			*val = ret;
+			return 0;
+		case hwmon_fan_fault:
+			ret = emc2305_show_fault(dev, channel);
+			if (ret < 0)
+				return ret;
+			*val = ret;
+			return 0;
+		default:
+			break;
+		}
+		break;
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_input:
+			ret = emc2305_show_pwm(dev, channel);
+			if (ret < 0)
+				return ret;
+			*val = ret;
+			return 0;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return -EOPNOTSUPP;
+};
+
+static const struct hwmon_ops emc2305_ops = {
+	.is_visible = emc2305_is_visible,
+	.read = emc2305_read,
+	.write = emc2305_write,
+};
+
+static const struct hwmon_channel_info *emc2305_info[] = {
+	HWMON_CHANNEL_INFO(fan,
+			   HWMON_F_INPUT | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_FAULT,
+			   HWMON_F_INPUT | HWMON_F_FAULT),
+	HWMON_CHANNEL_INFO(pwm,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT,
+			   HWMON_PWM_INPUT),
+	NULL
+};
+
+static const struct hwmon_chip_info emc2305_chip_info = {
+	.ops = &emc2305_ops,
+	.info = emc2305_info,
+};
+
+static int emc2305_identify(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct emc2305_data *data = i2c_get_clientdata(client);
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(client, EMC2305_REG_PRODUCT_ID);
+	if (ret < 0)
+		return ret;
+
+	switch (ret) {
+	case EMC2305:
+		data->pwm_num = 5;
+		break;
+	case EMC2303:
+		data->pwm_num = 3;
+		break;
+	case EMC2302:
+		data->pwm_num = 2;
+		break;
+	case EMC2301:
+		data->pwm_num = 1;
+		break;
+	default:
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int emc2305_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	struct device *dev = &client->dev;
+	struct emc2305_data *data;
+	struct emc2305_platform_data *pdata;
+	int vendor, device;
+	int ret;
+	int i;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	vendor = i2c_smbus_read_byte_data(client, EMC2305_REG_VENDOR);
+	if (vendor != EMC2305_VENDOR)
+		return -ENODEV;
+
+	device = i2c_smbus_read_byte_data(client, EMC2305_REG_DEVICE);
+	if (device != EMC2305_DEVICE)
+		return -ENODEV;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, data);
+	data->client = client;
+
+	ret = emc2305_identify(dev);
+	if (ret)
+		return ret;
+
+	pdata = dev_get_platdata(&client->dev);
+	if (pdata) {
+		if (!pdata->max_state || pdata->max_state > EMC2305_FAN_MAX_STATE)
+			return -EINVAL;
+		data->max_state = pdata->max_state;
+		/*
+		 * Validate a number of active PWM channels. Note that
+		 * configured number can be less than the actual maximum
+		 * supported by the device.
+		 */
+		if (!pdata->pwm_num || pdata->pwm_num > EMC2305_PWM_MAX)
+			return -EINVAL;
+		data->pwm_num = pdata->pwm_num;
+		data->pwm_separate = pdata->pwm_separate;
+		for (i = 0; i < EMC2305_PWM_MAX; i++)
+			data->pwm_min[i] = pdata->pwm_min[i];
+	} else {
+		data->max_state = EMC2305_FAN_MAX_STATE;
+		data->pwm_separate = false;
+		for (i = 0; i < EMC2305_PWM_MAX; i++)
+			data->pwm_min[i] = EMC2305_FAN_MIN;
+	}
+
+	data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "emc2305", data,
+							       &emc2305_chip_info, NULL);
+	if (IS_ERR(data->hwmon_dev))
+		return PTR_ERR(data->hwmon_dev);
+
+	if (IS_REACHABLE(CONFIG_THERMAL)) {
+		ret = emc2305_set_tz(dev);
+		if (ret != 0)
+			return ret;
+	}
+
+	for (i = 0; i < data->pwm_num; i++) {
+		ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_MIN_DRIVE(i),
+						data->pwm_min[i]);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int emc2305_remove(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+
+	if (IS_REACHABLE(CONFIG_THERMAL))
+		emc2305_unset_tz(dev);
+	return 0;
+}
+
+static struct i2c_driver emc2305_driver = {
+	.class  = I2C_CLASS_HWMON,
+	.driver = {
+		.name = "emc2305",
+	},
+	.probe    = emc2305_probe,
+	.remove	  = emc2305_remove,
+	.id_table = emc2305_ids,
+	.address_list = emc2305_normal_i2c,
+};
+
+module_i2c_driver(emc2305_driver);
+
+MODULE_AUTHOR("Nvidia");
+MODULE_DESCRIPTION("Microchip EMC2305 fan controller driver");
+MODULE_LICENSE("GPL");

From: Michael Shych <[email protected]>

Add description of emc2305 driver.

Signed-off-by Michael Shych <[email protected]>

Reviewed-by Vadim Pasternak <[email protected]>

---
v1->v2
- Add document to index.rst

---
 Documentation/hwmon/emc2305.rst | 40 ++++++++++++++++++++++++++++++++++++++++
 Documentation/hwmon/index.rst   |  1 +
 2 files changed, 41 insertions(+)
 create mode 100644 Documentation/hwmon/emc2305.rst

Documentation/hwmon/emc2305.rst new file +40 -0

new file mode 100644
index 000000000000..258da49d18f9
@@ -0,0 +1,40 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver emc2305
+=====================
+
+Supported chips:
+   Microchip EMC2305, EMC2303, EMC2302, EMC2301
+
+   Addresses scanned: I2C 0x27, 0x2c, 0x2d, 0x2e, 0x2f, 0x4c, 0x4d
+   Prefixes: 'emc2305'
+
+   Datasheet: Publicly available at the Microchip website :
+      https://www.microchip.com/en-us/product/EMC2305
+
+Description:
+-----------
+This driver implements support for Microchip EMC2301/2/3/5 RPM-based PWM Fan Controller.
+The EMC2305 Fan Controller supports up to 5 independently controlled PWM fan drives.
+Fan rotation speeds are reported in RPM.
+The driver supports the RPM-based PWM control to keep a fan at the desired speed.
+The driver provides the possibility to have one common PWM interface for all FANs
+or up to the maximum available or configured independent PWMs.
+
+The driver provides the following sysfs interfaces in hwmon subsystem:
+
+================= == ===================================================
+fan[1-5]_fault    RO files for tachometers TACH1-TACH5 fault indication
+fan[1-5]_input    RO files for tachometers TACH1-TACH5 input (in RPM)
+pwm[1-5]          RW file for fan[1-5] target duty cycle (0..255)
+================= == ===================================================
+
+sysfs interfaces in thermal subsystem:
+
+================= == ========================================================================
+cur_state         RW file for the current cooling state of the cooling device (0..max_state)
+max_state         RO file for the maximum cooling state of the cooling device
+================= == ========================================================================
+
+Configuration is possible via device tree:
+Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml

Documentation/hwmon/index.rst +1 -0

index f7113b0f8b2a..83b082d222af 100644
@@ -63,6 +63,7 @@ Hardware Monitoring Kernel Drivers
    ds620
    emc1403
    emc2103
+   emc2305
    emc6w201
    f71805f
    f71882fg