From 5ea2e152d846bf60901107fefd81a58f792f3bc2 Mon Sep 17 00:00:00 2001
From: Christian Lamparter <chunkeey@gmail.com>
Date: Fri, 10 Jun 2016 03:00:46 +0200
Subject: [PATCH] hwmon: add driver for Microchip TC654/TC655 PWM fan
 controllers

This patch adds a hwmon driver for the Microchip TC654 and TC655
Dual SMBus PWM Fan Speed Controllers with Fan Fault detection.

The chip is described in the DS2001734C Spec Document from Microchip.
It supports:
	- Shared PWM Fan Drive for two fans
	- Provides RPM
	- automatic PWM controller (needs additional
	  NTC/PTC Thermistors.)
	- Overtemperature alarm (when using NTC/PTC
	  Thermistors)

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
---
 drivers/hwmon/Kconfig  |  10 +
 drivers/hwmon/Makefile |   1 +
 drivers/hwmon/tc654.c  | 969 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 980 insertions(+)
 create mode 100644 drivers/hwmon/tc654.c

--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1484,6 +1484,16 @@ config SENSORS_INA2XX
 	  This driver can also be built as a module.  If so, the module
 	  will be called ina2xx.
 
+config SENSORS_TC654
+	tristate "Microchip TC654 and TC655"
+	depends on I2C
+	help
+	  If you say yes here you get support for Microchip TC655 and TC654
+	  Dual PWM Fan Speed Controllers and sensor chips.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called tc654.
+
 config SENSORS_TC74
 	tristate "Microchip TC74"
 	depends on I2C
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -143,6 +143,7 @@ obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc4
 obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
 obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
 obj-$(CONFIG_SENSORS_AMC6821)	+= amc6821.o
+obj-$(CONFIG_SENSORS_TC654)	+= tc654.o
 obj-$(CONFIG_SENSORS_TC74)	+= tc74.o
 obj-$(CONFIG_SENSORS_THMC50)	+= thmc50.o
 obj-$(CONFIG_SENSORS_TMP102)	+= tmp102.o
--- /dev/null
+++ b/drivers/hwmon/tc654.c
@@ -0,0 +1,969 @@
+/*
+ * tc654.c - Support for Microchip TC654/TC655
+ * "A Dual SMBus PWM FAN Speed Controllers with Fan Fault Detection"
+ *
+ * Copyright (c) 2016 Christian Lamparter <chunkeey@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * The chip is described in the DS2001734C Spec Document from Microchip.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/thermal.h>
+
+/* Hardware definitions */
+/* 5.1.4 Address Byte stats that TC654/TC655 are fixed at 0x1b */
+static const unsigned short normal_i2c[] = { 0x1b, I2C_CLIENT_END };
+
+enum TC654_REGS {
+	TC654_REG_RPM1 = 0x00,
+	TC654_REG_RPM2,
+	TC654_REG_FAN1_FAULT_THRESH,
+	TC654_REG_FAN2_FAULT_THRESH,
+	TC654_REG_CONFIG,
+	TC654_REG_STATUS,
+	TC654_REG_DUTY_CYCLE,
+	TC654_REG_MFR_ID,
+	TC654_REG_VER_ID,
+
+	/* keep last */
+	__TC654_REG_NUM,
+};
+
+#define TC654_MFR_ID_MICROCHIP		0x84
+#define TC654_VER_ID			0x00
+#define TC655_VER_ID			0x01
+
+enum TC654_CONTROL_BITS {
+	TC654_CTRL_SDM		= BIT(0),
+	TC654_CTRL_F1PPR_S	= 1,
+	TC654_CTRL_F1PPR_M	= (BIT(1) | BIT(2)),
+	TC654_CTRL_F2PPR_S	= 3,
+	TC654_CTRL_F2PPR_M	= (BIT(3) | BIT(4)),
+	TC654_CTRL_DUTYC	= BIT(5),
+	TC654_CTRL_RES		= BIT(6),
+	TC654_CTRL_FFCLR	= BIT(7),
+};
+
+enum TC654_STATUS_BITS {
+	TC654_STATUS_F1F	= BIT(0),
+	TC654_STATUS_F2F	= BIT(1),
+	TC654_STATUS_VSTAT	= BIT(2),
+	TC654_STATUS_R1CO	= BIT(3),
+	TC654_STATUS_R2CO	= BIT(4),
+	TC654_STATUS_OTF	= BIT(5),
+};
+
+enum TC654_FAN {
+	TC654_FAN1 = 0,
+	TC654_FAN2,
+
+	/* keep last */
+	__NUM_TC654_FAN,
+};
+
+enum TC654_FAN_MODE {
+	TC654_PWM_OFF,	/* Shutdown Mode - switch of both fans */
+	TC654_PWM_VIN,	/* Fans will be controlled via V_in analog input pin */
+	TC654_PWM_3000,	/* sets fans to 30% duty cycle */
+	TC654_PWM_3467,
+	TC654_PWM_3933, /* default case - if V_in pin is open */
+	TC654_PWM_4400,
+	TC654_PWM_4867,
+	TC654_PWM_5333,
+	TC654_PWM_5800,
+	TC654_PWM_6267,
+	TC654_PWM_6733,
+	TC654_PWM_7200,
+	TC654_PWM_7667,
+	TC654_PWM_8133,
+	TC654_PWM_8600,
+	TC654_PWM_9067,
+	TC654_PWM_9533,
+	TC654_PWM_10000, /* sets fans to 100% duty cycle */
+};
+
+enum TC654_ALARMS {
+	TC654_ALARM_FAN1_FAULT,
+	TC654_ALARM_FAN2_FAULT,
+	TC654_ALARM_FAN1_COUNTER_OVERFLOW,
+	TC654_ALARM_FAN2_COUNTER_OVERFLOW,
+	TC654_ALARM_OVER_TEMPERATURE,
+
+	/* KEEP LAST */
+	__NUM_TC654_ALARMS,
+};
+
+static const struct pwm_table_entry {
+	u8 min;
+	enum TC654_FAN_MODE mode;
+} pwm_table[] = {
+	{  0, TC654_PWM_OFF  },
+	{  1, TC654_PWM_3000 },
+	{ 88, TC654_PWM_3467 },
+	{101, TC654_PWM_3933 },
+	{113, TC654_PWM_4400 },
+	{125, TC654_PWM_4867 },
+	{137, TC654_PWM_5333 },
+	{148, TC654_PWM_5800 },
+	{160, TC654_PWM_6267 },
+	{172, TC654_PWM_6733 },
+	{184, TC654_PWM_7200 },
+	{196, TC654_PWM_7667 },
+	{208, TC654_PWM_8133 },
+	{220, TC654_PWM_8600 },
+	{232, TC654_PWM_9067 },
+	{244, TC654_PWM_9533 },
+	{255, TC654_PWM_10000 },
+};
+
+/* driver context */
+struct tc654 {
+	struct i2c_client	*client;
+
+	struct mutex		update_lock;
+
+	unsigned long		last_updated;	/* in jiffies */
+	u8			cached_regs[__TC654_REG_NUM];
+
+	bool			valid;	/* monitored registers are valid */
+	u16			fan_input[__NUM_TC654_FAN];
+	bool			alarms[__NUM_TC654_ALARMS];
+	bool			vin_status;
+	bool			pwm_manual;
+
+	/* optional cooling device */
+	struct thermal_cooling_device *cdev;
+};
+
+/* hardware accessors and functions */
+static int read_tc(struct tc654 *tc, u8 reg)
+{
+	s32 status;
+
+	if (reg <= TC654_REG_VER_ID) {
+		/* Table 6.1 states that all registers are readable */
+		status = i2c_smbus_read_byte_data(tc->client, reg);
+	} else
+		status = -EINVAL;
+
+	if (status < 0) {
+		dev_warn(&tc->client->dev, "can't read register 0x%02x due to error (%d)",
+			 reg, status);
+	} else {
+		tc->cached_regs[reg] = status;
+	}
+
+	return status;
+}
+
+static int write_tc(struct tc654 *tc, u8 i2c_reg, u8 val)
+{
+	s32 status;
+
+	/*
+	 * Table 6.1 states that both fan threshold registers,
+	 * the Config and Duty Cycle are writeable.
+	 */
+	switch (i2c_reg) {
+	case TC654_REG_FAN1_FAULT_THRESH:
+	case TC654_REG_FAN2_FAULT_THRESH:
+	case TC654_REG_DUTY_CYCLE:
+	case TC654_REG_CONFIG:
+		status = i2c_smbus_write_byte_data(tc->client, i2c_reg, val);
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	if (status < 0) {
+		dev_warn(&tc->client->dev, "can't write register 0x%02x with value 0x%02x due to error (%d)",
+			 i2c_reg, val, status);
+	} else {
+		tc->cached_regs[i2c_reg] = val;
+	}
+
+	return status;
+}
+
+static int mod_config(struct tc654 *tc, u8 set, u8 clear)
+{
+	u8 val = 0;
+
+	/* a bit can't be set and cleared on the same time. */
+	if (set & clear)
+		return -EINVAL;
+
+	/* invalidate data to force re-read from hardware */
+	tc->valid = false;
+	val = (tc->cached_regs[TC654_REG_CONFIG] | set) & (~clear);
+	return write_tc(tc, TC654_REG_CONFIG, val);
+}
+
+static int read_fan_rpm(struct tc654 *tc, enum TC654_FAN fan)
+{
+	int ret;
+
+	/* 6.1 RPM-OUTPUT1 and RPM-OUTPUT2 registers */
+	ret = read_tc(tc, fan == TC654_FAN1 ? TC654_REG_RPM1 : TC654_REG_RPM2);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * The Resolution Selection Bit in 6.3 CONFIGURATION REGISTER
+	 * is needed to convert the raw value to the RPM.
+	 * 0 = RPM1 and RPM2 use (8-Bit) resolution => * 50 RPM
+	 * 1 = RPM1 and RPM2 use (9-Bit) resolution => * 25 RPM
+	 */
+	return ret * (25 <<
+		!(tc->cached_regs[TC654_REG_CONFIG] & TC654_CTRL_RES));
+}
+
+static int write_fan_fault_thresh(struct tc654 *tc, enum TC654_FAN fan,
+				  u16 rpm)
+{
+	u8 converted_rpm;
+
+	if (rpm > 12750)
+		return -EINVAL;
+
+	/*
+	 * 6.2 FAN_FAULT1 and FAN_FAULT2 Threshold registers
+	 *
+	 * Both registers operate in 50 RPM mode exclusively.
+	 */
+	converted_rpm = rpm / 50;
+
+	/* invalidate data to force re-read from hardware */
+	tc->valid = false;
+	return write_tc(tc, fan == TC654_FAN1 ? TC654_REG_FAN1_FAULT_THRESH :
+		TC654_REG_FAN2_FAULT_THRESH, converted_rpm);
+}
+
+
+static int read_fan_fault_thresh(struct tc654 *tc, enum TC654_FAN fan)
+{
+	/*
+	 * 6.2 FAN_FAULT1 and FAN_FAULT2 Threshold registers
+	 *
+	 * Both registers operate in 50 RPM mode exclusively.
+	 */
+	return read_tc(tc, fan == TC654_FAN1 ? TC654_REG_FAN1_FAULT_THRESH :
+		TC654_REG_FAN2_FAULT_THRESH) * 50;
+}
+
+static enum TC654_FAN_MODE get_fan_mode(struct tc654 *tc)
+{
+	if (tc->cached_regs[TC654_REG_CONFIG] & TC654_CTRL_SDM) {
+		return TC654_PWM_OFF;
+	} else if (tc->cached_regs[TC654_REG_CONFIG] & TC654_CTRL_DUTYC) {
+		return TC654_PWM_3000 + tc->cached_regs[TC654_REG_DUTY_CYCLE];
+	} else if (tc->vin_status == 0)
+		return TC654_PWM_VIN;
+
+	return -EINVAL;
+}
+
+static int write_fan_mode(struct tc654 *tc, enum TC654_FAN_MODE mode)
+{
+	int err;
+	u8 pwm_mode;
+	bool in_sdm;
+
+	in_sdm = !!(tc->cached_regs[TC654_REG_CONFIG] &
+		TC654_CTRL_SDM);
+
+	switch (mode) {
+	case TC654_PWM_OFF:
+		if (in_sdm)
+			return 0;
+
+		/* Enter Shutdown Mode - Switches off all fans */
+		err = mod_config(tc, TC654_CTRL_SDM, TC654_CTRL_DUTYC);
+		if (err)
+			return err;
+
+		return 0;
+
+	case TC654_PWM_VIN:
+		if (tc->vin_status) {
+			dev_err(&tc->client->dev,
+				"V_in pin is open, can't enable automatic mode.");
+			return -EINVAL;
+		}
+
+		err = mod_config(tc, 0, TC654_CTRL_SDM | TC654_CTRL_DUTYC);
+		if (err)
+			return err;
+
+		tc->pwm_manual = false;
+		return 0;
+
+	case TC654_PWM_3000:
+	case TC654_PWM_3467:
+	case TC654_PWM_3933:
+	case TC654_PWM_4400:
+	case TC654_PWM_4867:
+	case TC654_PWM_5333:
+	case TC654_PWM_5800:
+	case TC654_PWM_6267:
+	case TC654_PWM_6733:
+	case TC654_PWM_7200:
+	case TC654_PWM_7667:
+	case TC654_PWM_8133:
+	case TC654_PWM_8600:
+	case TC654_PWM_9067:
+	case TC654_PWM_9533:
+	case TC654_PWM_10000:
+		pwm_mode = mode - TC654_PWM_3000;
+		if (!in_sdm) {
+			err = write_tc(tc, TC654_REG_DUTY_CYCLE, pwm_mode);
+			if (err)
+				return err;
+		}
+
+		err = mod_config(tc, TC654_CTRL_DUTYC, TC654_CTRL_SDM);
+		if (err)
+			return err;
+
+		tc->pwm_manual = true;
+
+		if (in_sdm) {
+			/*
+			 * In case the TC654/TC655 was in SDM mode, the write
+			 * above into the TC654_REG_DUTY_CYCLE register will
+			 * have no effect because the chip was switched off.
+			 *
+			 * Note: The TC654/TC655 have a special "power-on"
+			 * feature where the PWM will be forced to 100% for
+			 * one full second in order to spin-up a resting fan.
+			 */
+			err = write_tc(tc, TC654_REG_DUTY_CYCLE, pwm_mode);
+			if (err)
+				return err;
+		}
+
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static struct tc654 *tc654_update_device(struct device *dev)
+{
+	struct tc654 *tc = dev_get_drvdata(dev);
+
+	mutex_lock(&tc->update_lock);
+
+	/*
+	 * In Chapter "1.0 Electrical Characteristics",
+	 * the "Fault Output Response Time" is specified as 2.4 seconds.
+	 */
+	if (time_after(jiffies, tc->last_updated + 2 * HZ + (HZ * 2) / 5)
+	    || !tc->valid) {
+		size_t i;
+		int ret;
+		bool alarm_triggered;
+
+		tc->valid = false;
+
+		for (i = 0; i < __NUM_TC654_FAN; i++) {
+			ret = read_fan_rpm(tc, i);
+			if (ret < 0)
+				goto out;
+
+			tc->fan_input[i] = ret;
+		}
+
+		ret = read_tc(tc, TC654_REG_STATUS);
+		if (ret < 0)
+			goto out;
+
+		alarm_triggered = !!(ret & (TC654_STATUS_F1F |
+			TC654_STATUS_F2F | TC654_STATUS_R1CO |
+			TC654_STATUS_R2CO | TC654_STATUS_OTF));
+
+		tc->alarms[TC654_ALARM_FAN1_FAULT] = !!(ret & TC654_STATUS_F1F);
+		tc->alarms[TC654_ALARM_FAN2_FAULT] = !!(ret & TC654_STATUS_F2F);
+		tc->alarms[TC654_ALARM_FAN1_COUNTER_OVERFLOW] =
+			!!(ret & TC654_STATUS_R1CO);
+		tc->alarms[TC654_ALARM_FAN2_COUNTER_OVERFLOW] =
+			!!(ret & TC654_STATUS_R2CO);
+		tc->alarms[TC654_ALARM_OVER_TEMPERATURE] =
+			!!(ret & TC654_STATUS_OTF);
+		tc->vin_status = !!(ret & TC654_STATUS_VSTAT);
+
+		/*
+		 * From 4.5 and 6.3
+		 *
+		 * ... "If the V_in pin is open when TC654_CTRL_DUTYC is not
+		 * selected, then V_out duty cycle will default to 39.33%.".
+		 *
+		 * and most importantly 6.5:
+		 * ... "V_in pin is open, the duty cycle will go to the default
+		 * setting of this register, which is 0010 (39.33%)."
+		 */
+		tc->pwm_manual |= tc->vin_status &&
+			(tc->cached_regs[TC654_REG_CONFIG] &
+			 TC654_CTRL_DUTYC);
+
+		if (alarm_triggered) {
+			/*
+			 * as the name implies, this FLAG needs to be
+			 * set in order to clear the FAN Fault error.
+			 */
+			ret = mod_config(tc, TC654_CTRL_FFCLR, 0);
+			if (ret < 0)
+				goto out;
+		}
+
+		tc->last_updated = jiffies;
+		tc->valid = true;
+	}
+
+out:
+	mutex_unlock(&tc->update_lock);
+	return tc;
+}
+
+static u8 get_fan_pulse(struct tc654 *tc, enum TC654_FAN fan)
+{
+	u8 fan_pulse_mask = fan == TC654_FAN1 ?
+		TC654_CTRL_F1PPR_M : TC654_CTRL_F2PPR_M;
+	u8 fan_pulse_shift = fan  == TC654_FAN1 ?
+		TC654_CTRL_F1PPR_S : TC654_CTRL_F2PPR_S;
+
+	return 1 << ((tc->cached_regs[TC654_REG_CONFIG] & fan_pulse_mask) >>
+		     fan_pulse_shift);
+}
+
+static int
+set_fan_pulse(struct tc654 *tc, enum TC654_FAN fan, int pulses)
+{
+	int old_pulses;
+	int err;
+	u8 new_pulse_per_rotation;
+	u8 fan_pulse_mask = fan == TC654_FAN1 ?
+		TC654_CTRL_F1PPR_M : TC654_CTRL_F2PPR_M;
+	u8 fan_pulse_shift = fan  == TC654_FAN1 ?
+		TC654_CTRL_F1PPR_S : TC654_CTRL_F2PPR_S;
+
+	switch (pulses) {
+	case 1:
+		new_pulse_per_rotation = 0;
+		break;
+	case 2:
+		new_pulse_per_rotation = 1;
+		break;
+	case 4:
+		new_pulse_per_rotation = 2;
+		break;
+	case 8:
+		new_pulse_per_rotation = 3;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	new_pulse_per_rotation <<= fan_pulse_shift;
+	new_pulse_per_rotation &= fan_pulse_mask;
+
+	old_pulses = tc->cached_regs[TC654_REG_CONFIG];
+	old_pulses &= fan_pulse_mask;
+
+	if (new_pulse_per_rotation == old_pulses)
+		return 0;
+
+	mutex_lock(&tc->update_lock);
+	err = mod_config(tc, new_pulse_per_rotation,
+			    old_pulses & (~new_pulse_per_rotation));
+	mutex_unlock(&tc->update_lock);
+
+	/* invalidate RPM data to force re-read from hardware */
+	tc->valid = false;
+
+	return err;
+}
+
+static int get_fan_speed(struct tc654 *tc)
+{
+	enum TC654_FAN_MODE mode;
+	size_t i;
+
+	mode = get_fan_mode(tc);
+	for (i = 0; i < ARRAY_SIZE(pwm_table); i++) {
+		if (mode == pwm_table[i].mode)
+			return pwm_table[i].min;
+	}
+
+	return -EINVAL;
+}
+
+static int set_fan_speed(struct tc654 *tc, int new_value)
+{
+	int result;
+	size_t i;
+
+	if (new_value > pwm_table[ARRAY_SIZE(pwm_table) - 1].min ||
+	    new_value < pwm_table[0].min)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(pwm_table); i++) {
+		/* exact match */
+		if (pwm_table[i].min == new_value)
+			break;
+
+		/* a little bit too big - go with the previous entry */
+		if (pwm_table[i].min > new_value) {
+			--i;
+			break;
+		}
+	}
+
+	mutex_lock(&tc->update_lock);
+	result = write_fan_mode(tc, pwm_table[i].mode);
+	mutex_unlock(&tc->update_lock);
+	if (result < 0)
+		return result;
+
+	return 0;
+}
+
+/* sysfs */
+
+static ssize_t
+show_fan_input(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct tc654 *tc = tc654_update_device(dev);
+	int nr = to_sensor_dev_attr(da)->index;
+
+	return sprintf(buf, "%d\n", tc->fan_input[nr]);
+}
+
+static ssize_t
+show_fan_min(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct tc654 *tc = dev_get_drvdata(dev);
+	int nr = to_sensor_dev_attr(da)->index;
+
+	return sprintf(buf, "%d\n", read_fan_fault_thresh(tc, nr));
+}
+
+static ssize_t
+show_fan_min_alarm(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct tc654 *tc = tc654_update_device(dev);
+	int nr = to_sensor_dev_attr(da)->index;
+
+	return sprintf(buf, "%d\n", nr == TC654_FAN1 ?
+		       tc->alarms[TC654_ALARM_FAN1_FAULT] :
+		       tc->alarms[TC654_ALARM_FAN2_FAULT]);
+}
+
+static ssize_t
+show_fan_max_alarm(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct tc654 *tc = tc654_update_device(dev);
+	int nr = to_sensor_dev_attr(da)->index;
+
+	return sprintf(buf, "%d\n", nr == TC654_FAN1 ?
+		       tc->alarms[TC654_ALARM_FAN1_COUNTER_OVERFLOW] :
+		       tc->alarms[TC654_ALARM_FAN2_COUNTER_OVERFLOW]);
+}
+
+static ssize_t
+set_fan_min(struct device *dev, struct device_attribute *da,
+	    const char *buf, size_t count)
+{
+	struct tc654 *tc = dev_get_drvdata(dev);
+	long new_min;
+	int nr = to_sensor_dev_attr(da)->index;
+	int old_min = read_fan_fault_thresh(tc, nr);
+	int status = kstrtol(buf, 10, &new_min);
+
+	if (status < 0)
+		return status;
+
+	new_min = (new_min / 50) * 50;
+	if (new_min == old_min) /* No change */
+		return count;
+
+	if (new_min < 0 || new_min > 12750)
+		return -EINVAL;
+
+	mutex_lock(&tc->update_lock);
+	status = write_fan_fault_thresh(tc, nr, new_min);
+	mutex_unlock(&tc->update_lock);
+	return count;
+}
+
+static ssize_t
+show_fan_max(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct tc654 *tc = dev_get_drvdata(dev);
+	int max_rpm = tc->cached_regs[TC654_REG_CONFIG] & TC654_CTRL_RES ?
+		(((1 << 9) - 1) * 25) /* ((2**9) - 1) * 25 RPM */:
+		(((1 << 8) - 1) * 50) /* ((2**8) - 1) * 50 RPM */;
+
+	return sprintf(buf, "%d\n", max_rpm);
+}
+
+static ssize_t
+show_fan_fault(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct tc654 *tc = tc654_update_device(dev);
+	int nr = to_sensor_dev_attr(da)->index;
+	u8 fan_fault_mask = nr == TC654_FAN1 ?
+		TC654_STATUS_F1F : TC654_STATUS_F2F;
+
+	return sprintf(buf, "%d\n",
+		!!(tc->cached_regs[TC654_REG_STATUS] & fan_fault_mask));
+}
+
+static ssize_t
+show_fan_pulses(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct tc654 *tc = dev_get_drvdata(dev);
+	int nr = to_sensor_dev_attr(da)->index;
+
+	return sprintf(buf, "%d\n", get_fan_pulse(tc, nr));
+}
+
+static ssize_t
+set_fan_pulses(struct device *dev, struct device_attribute *da,
+	      const char *buf, size_t count)
+{
+	struct tc654 *tc = dev_get_drvdata(dev);
+	long new_pulse;
+	int nr = to_sensor_dev_attr(da)->index;
+	int status = kstrtol(buf, 10, &new_pulse);
+
+	if (status < 0)
+		return status;
+
+	status = set_fan_pulse(tc, nr, new_pulse);
+	if (status < 0)
+		return status;
+
+	return count;
+}
+
+static ssize_t
+show_pwm_enable(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct tc654 *tc = tc654_update_device(dev);
+	int pwm_enabled;
+
+	if ((tc->cached_regs[TC654_REG_CONFIG] & TC654_CTRL_SDM) &&
+	    !tc->pwm_manual) {
+		pwm_enabled = 0; /* full off */
+	} else {
+		if (tc->valid && tc->vin_status == 0)
+			pwm_enabled = 2; /* automatic fan speed control */
+
+		pwm_enabled = 1; /* PWM Mode */
+	}
+
+	return sprintf(buf, "%d\n", pwm_enabled);
+}
+
+static ssize_t
+set_pwm_enable(struct device *dev, struct device_attribute *da,
+	       const char *buf, size_t count)
+{
+	struct tc654 *tc = dev_get_drvdata(dev);
+	long new_value;
+
+	int result = kstrtol(buf, 10, &new_value);
+
+	if (result < 0)
+		return result;
+
+	mutex_lock(&tc->update_lock);
+	switch (new_value) {
+	case 0: /* no fan control (i.e. is OFF) */
+		result = write_fan_mode(tc, TC654_PWM_OFF);
+		tc->pwm_manual = false;
+		break;
+
+	case 1: /* manual fan control enabled (using pwm) */
+		result = write_fan_mode(tc, TC654_PWM_10000);
+		break;
+
+	case 2: /* automatic fan speed control enabled */
+		result = write_fan_mode(tc, TC654_PWM_VIN);
+		break;
+
+	default:
+		result = -EINVAL;
+	}
+
+	mutex_unlock(&tc->update_lock);
+	return result < 0 ? result : count;
+}
+
+static ssize_t
+show_pwm(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct tc654 *tc = tc654_update_device(dev);
+	int ret;
+
+	ret = get_fan_speed(tc);
+	if (ret < 0)
+		return ret;
+
+	return sprintf(buf, "%d\n", ret);
+}
+
+static ssize_t
+set_pwm(struct device *dev, struct device_attribute *da,
+	const char *buf, size_t count)
+{
+	struct tc654 *tc = dev_get_drvdata(dev);
+	long new_value = -1;
+	int result = kstrtol(buf, 10, &new_value);
+
+	if (result < 0)
+		return result;
+
+	if (new_value < 0 || new_value > INT_MAX)
+		return -EINVAL;
+
+	if (!tc->pwm_manual)
+		return -EINVAL;
+
+	result = set_fan_speed(tc, new_value);
+	if (result < 0)
+		return result;
+
+	return count;
+}
+
+static ssize_t
+show_temp_alarm_otf(struct device *dev, struct device_attribute *da, char *buf)
+{
+	struct tc654 *tc = tc654_update_device(dev);
+
+	return sprintf(buf, "%d\n", tc->alarms[TC654_ALARM_OVER_TEMPERATURE]);
+}
+
+static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, show_fan_input,
+			  NULL, TC654_FAN1);
+static SENSOR_DEVICE_ATTR(fan1_min, S_IRUGO | S_IWUSR, show_fan_min,
+			  set_fan_min, TC654_FAN1);
+static SENSOR_DEVICE_ATTR(fan1_min_alarm, S_IRUGO, show_fan_min_alarm,
+			  NULL, TC654_FAN1);
+static SENSOR_DEVICE_ATTR(fan1_max_alarm, S_IRUGO, show_fan_max_alarm,
+			  NULL, TC654_FAN1);
+static SENSOR_DEVICE_ATTR(fan1_max, S_IRUGO, show_fan_max, NULL, TC654_FAN1);
+static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, show_fan_fault,
+			  NULL, TC654_FAN1);
+static SENSOR_DEVICE_ATTR(fan1_pulses, S_IRUGO | S_IWUSR, show_fan_pulses,
+			  set_fan_pulses, TC654_FAN1);
+static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, show_fan_input,
+			  NULL, TC654_FAN2);
+static SENSOR_DEVICE_ATTR(fan2_min, S_IRUGO | S_IWUSR, show_fan_min,
+			  set_fan_min, TC654_FAN2);
+static SENSOR_DEVICE_ATTR(fan2_max, S_IRUGO, show_fan_max,
+			  NULL, TC654_FAN2);
+static SENSOR_DEVICE_ATTR(fan2_min_alarm, S_IRUGO, show_fan_min_alarm,
+			  NULL, TC654_FAN2);
+static SENSOR_DEVICE_ATTR(fan2_max_alarm, S_IRUGO, show_fan_max_alarm,
+			  NULL, TC654_FAN2);
+static SENSOR_DEVICE_ATTR(fan2_fault, S_IRUGO, show_fan_fault,
+			  NULL, TC654_FAN2);
+static SENSOR_DEVICE_ATTR(fan2_pulses, S_IRUGO | S_IWUSR, show_fan_pulses,
+			  set_fan_pulses, TC654_FAN2);
+
+static DEVICE_ATTR(pwm1_enable, S_IRUGO | S_IWUSR, show_pwm_enable,
+	set_pwm_enable);
+static DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm);
+
+static DEVICE_ATTR(temp1_emergency_alarm, S_IRUGO, show_temp_alarm_otf, NULL);
+
+/* sensors present on all models */
+static struct attribute *tc654_attrs[] = {
+	&sensor_dev_attr_fan1_input.dev_attr.attr,
+	&sensor_dev_attr_fan1_min.dev_attr.attr,
+	&sensor_dev_attr_fan1_max.dev_attr.attr,
+	&sensor_dev_attr_fan1_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_fan1_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_fan1_fault.dev_attr.attr,
+	&sensor_dev_attr_fan1_pulses.dev_attr.attr,
+	&sensor_dev_attr_fan2_input.dev_attr.attr,
+	&sensor_dev_attr_fan2_min.dev_attr.attr,
+	&sensor_dev_attr_fan2_max.dev_attr.attr,
+	&sensor_dev_attr_fan2_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_fan2_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_fan2_fault.dev_attr.attr,
+	&sensor_dev_attr_fan2_pulses.dev_attr.attr,
+
+	&dev_attr_pwm1_enable.attr,
+	&dev_attr_pwm1.attr,
+
+	&dev_attr_temp1_emergency_alarm.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(tc654);
+
+/* cooling device */
+
+static int tc654_get_max_state(struct thermal_cooling_device *cdev,
+			       unsigned long *state)
+{
+	*state = 255;
+	return 0;
+}
+
+static int tc654_get_cur_state(struct thermal_cooling_device *cdev,
+			       unsigned long *state)
+{
+	struct tc654 *tc = cdev->devdata;
+	int ret;
+
+	if (!tc)
+		return -EINVAL;
+
+	ret = get_fan_speed(tc);
+	if (ret < 0)
+		return ret;
+
+	*state = ret;
+	return 0;
+}
+
+static int tc654_set_cur_state(struct thermal_cooling_device *cdev,
+			       unsigned long state)
+{
+	struct tc654 *tc = cdev->devdata;
+
+	if (!tc)
+		return -EINVAL;
+
+	if (state > INT_MAX)
+		return -EINVAL;
+
+	return set_fan_speed(tc, state);
+}
+
+static const struct thermal_cooling_device_ops tc654_fan_cool_ops = {
+	.get_max_state = tc654_get_max_state,
+	.get_cur_state = tc654_get_cur_state,
+	.set_cur_state = tc654_set_cur_state,
+};
+
+
+/* hardware probe and detection */
+
+static int
+tc654_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+	struct tc654 *tc;
+	struct device *hwmon_dev;
+	int ret, i;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -EIO;
+
+	tc = devm_kzalloc(&client->dev, sizeof(*tc), GFP_KERNEL);
+	if (!tc)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, tc);
+	tc->client = client;
+	mutex_init(&tc->update_lock);
+
+	/* cache all 8 registers */
+	for (i = 0; i < __TC654_REG_NUM; i++) {
+		ret = read_tc(tc, i);
+		if (ret < 0)
+			return ret;
+	}
+
+	/* sysfs hooks */
+	hwmon_dev = devm_hwmon_device_register_with_groups(&client->dev,
+							   client->name, tc,
+							   tc654_groups);
+	if (IS_ERR(hwmon_dev))
+		return PTR_ERR(hwmon_dev);
+
+#if IS_ENABLED(CONFIG_OF)
+	/* Optional cooling device register for Device tree platforms */
+	tc->cdev = thermal_of_cooling_device_register(client->dev.of_node,
+						      "tc654", tc,
+						      &tc654_fan_cool_ops);
+#else /* CONFIG_OF */
+	/* Optional cooling device register for non Device tree platforms */
+	tc->cdev = thermal_cooling_device_register("tc654", tc,
+						   &tc654_fan_cool_ops);
+#endif /* CONFIG_OF */
+
+	dev_info(&client->dev, "%s: sensor '%s'\n",
+		 dev_name(hwmon_dev), client->name);
+
+	return 0;
+}
+
+static const struct i2c_device_id tc654_ids[] = {
+	{ "tc654", 0, },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tc654_ids);
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int
+tc654_detect(struct i2c_client *new_client, struct i2c_board_info *info)
+{
+	struct i2c_adapter *adapter = new_client->adapter;
+	int manufacturer, product;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	manufacturer = i2c_smbus_read_byte_data(new_client, TC654_REG_MFR_ID);
+	if (manufacturer != TC654_MFR_ID_MICROCHIP)
+		return -ENODEV;
+
+	product = i2c_smbus_read_byte_data(new_client, TC654_REG_VER_ID);
+	if (!((product == TC654_VER_ID) || (product == TC655_VER_ID)))
+		return -ENODEV;
+
+	strlcpy(info->type, "tc654", I2C_NAME_SIZE);
+	return 0;
+}
+
+static struct i2c_driver tc654_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name	= "tc654",
+	},
+	.probe		= tc654_probe,
+	.id_table	= tc654_ids,
+	.detect		= tc654_detect,
+	.address_list	= normal_i2c,
+};
+
+module_i2c_driver(tc654_driver);
+
+MODULE_AUTHOR("Christian Lamparter <chunkeey@gmail.com>");
+MODULE_DESCRIPTION("Microchip TC654/TC655 hwmon driver");
+MODULE_LICENSE("GPL");
