drivers/hwmon/mlxreg-fan.c - linux - Git at Google

 // SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
 //
 // Copyright (c) 2018 Mellanox Technologies. All rights reserved.
 // Copyright (c) 2018 Vadim Pasternak <vadimp@mellanox.com>

 #include <linux/bitops.h>
 #include <linux/device.h>
 #include <linux/hwmon.h>
 #include <linux/module.h>
 #include <linux/platform_data/mlxreg.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/thermal.h>

 #define MLXREG_FAN_MAX_TACHO		12
 #define MLXREG_FAN_MAX_STATE		10
 #define MLXREG_FAN_MIN_DUTY		51	/* 20% */
 #define MLXREG_FAN_MAX_DUTY		255	/* 100% */
 /*
  * Minimum and maximum FAN allowed speed in percent: from 20% to 100%. Values
  * MLXREG_FAN_MAX_STATE + x, where x is between 2 and 10 are used for
  * setting FAN speed dynamic minimum. For example, if value is set to 14 (40%)
  * cooling levels vector will be set to 4, 4, 4, 4, 4, 5, 6, 7, 8, 9, 10 to
  * introduce PWM speed in percent: 40, 40, 40, 40, 40, 50, 60. 70, 80, 90, 100.
  */
 #define MLXREG_FAN_SPEED_MIN			(MLXREG_FAN_MAX_STATE + 2)
 #define MLXREG_FAN_SPEED_MAX			(MLXREG_FAN_MAX_STATE * 2)
 #define MLXREG_FAN_SPEED_MIN_LEVEL		2	/* 20 percent */
 #define MLXREG_FAN_TACHO_SAMPLES_PER_PULSE_DEF	44
 #define MLXREG_FAN_TACHO_DIV_MIN		283
 #define MLXREG_FAN_TACHO_DIV_DEF		(MLXREG_FAN_TACHO_DIV_MIN * 4)
 #define MLXREG_FAN_TACHO_DIV_SCALE_MAX	64
 /*
  * FAN datasheet defines the formula for RPM calculations as RPM = 15/t-high.
  * The logic in a programmable device measures the time t-high by sampling the
  * tachometer every t-sample (with the default value 11.32 uS) and increment
  * a counter (N) as long as the pulse has not change:
  * RPM = 15 / (t-sample * (K + Regval)), where:
  * Regval: is the value read from the programmable device register;
  *  - 0xff - represents tachometer fault;
  *  - 0xfe - represents tachometer minimum value , which is 4444 RPM;
  *  - 0x00 - represents tachometer maximum value , which is 300000 RPM;
  * K: is 44 and it represents the minimum allowed samples per pulse;
  * N: is equal K + Regval;
  * In order to calculate RPM from the register value the following formula is
  * used: RPM = 15 / ((Regval + K) * 11.32) * 10^(-6)), which in  the
  * default case is modified to:
  * RPM = 15000000 * 100 / ((Regval + 44) * 1132);
  * - for Regval 0x00, RPM will be 15000000 * 100 / (44 * 1132) = 30115;
  * - for Regval 0xfe, RPM will be 15000000 * 100 / ((254 + 44) * 1132) = 4446;
  * In common case the formula is modified to:
  * RPM = 15000000 * 100 / ((Regval + samples) * divider).
  */
 #define MLXREG_FAN_GET_RPM(rval, d, s)	(DIV_ROUND_CLOSEST(15000000 * 100, \
 					 ((rval) + (s)) * (d)))
 #define MLXREG_FAN_GET_FAULT(val, mask) ((val) == (mask))
 #define MLXREG_FAN_PWM_DUTY2STATE(duty)	(DIV_ROUND_CLOSEST((duty) *	\
 					 MLXREG_FAN_MAX_STATE,		\
 					 MLXREG_FAN_MAX_DUTY))
 #define MLXREG_FAN_PWM_STATE2DUTY(stat)	(DIV_ROUND_CLOSEST((stat) *	\
 					 MLXREG_FAN_MAX_DUTY,		\
 					 MLXREG_FAN_MAX_STATE))

 /*
  * struct mlxreg_fan_tacho - tachometer data (internal use):
  *
  * @connected: indicates if tachometer is connected;
  * @reg: register offset;
  * @mask: fault mask;
  * @prsnt: present register offset;
  */
 struct mlxreg_fan_tacho {
 	bool connected;
 	u32 reg;
 	u32 mask;
 	u32 prsnt;
 };

 /*
  * struct mlxreg_fan_pwm - PWM data (internal use):
  *
  * @connected: indicates if PWM is connected;
  * @reg: register offset;
  */
 struct mlxreg_fan_pwm {
 	bool connected;
 	u32 reg;
 };

 /*
  * struct mlxreg_fan - private data (internal use):
  *
  * @dev: basic device;
  * @regmap: register map of parent device;
  * @tacho: tachometer data;
  * @pwm: PWM data;
  * @tachos_per_drwr - number of tachometers per drawer;
  * @samples: minimum allowed samples per pulse;
  * @divider: divider value for tachometer RPM calculation;
  * @cooling: cooling device levels;
  * @cdev: cooling device;
  */
 struct mlxreg_fan {
 	struct device *dev;
 	void *regmap;
 	struct mlxreg_core_platform_data *pdata;
 	struct mlxreg_fan_tacho tacho[MLXREG_FAN_MAX_TACHO];
 	struct mlxreg_fan_pwm pwm;
 	int tachos_per_drwr;
 	int samples;
 	int divider;
 	u8 cooling_levels[MLXREG_FAN_MAX_STATE + 1];
 	struct thermal_cooling_device *cdev;
 };

 static int
 mlxreg_fan_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
 		int channel, long *val)
 {
 	struct mlxreg_fan *fan = dev_get_drvdata(dev);
 	struct mlxreg_fan_tacho *tacho;
 	u32 regval;
 	int err;

 	switch (type) {
 	case hwmon_fan:
 		tacho = &fan->tacho[channel];
 		switch (attr) {
 		case hwmon_fan_input:
 			/*
 			 * Check FAN presence: FAN related bit in presence register is one,
 			 * if FAN is physically connected, zero - otherwise.
 			 */
 			if (tacho->prsnt && fan->tachos_per_drwr) {
 				err = regmap_read(fan->regmap, tacho->prsnt, &regval);
 				if (err)
 					return err;

 				/*
 				 * Map channel to presence bit - drawer can be equipped with
 				 * one or few FANs, while presence is indicated per drawer.
 				 */
 				if (BIT(channel / fan->tachos_per_drwr) & regval) {
 					/* FAN is not connected - return zero for FAN speed. */
 					*val = 0;
 					return 0;
 				}
 			}

 			err = regmap_read(fan->regmap, tacho->reg, &regval);
 			if (err)
 				return err;

 			*val = MLXREG_FAN_GET_RPM(regval, fan->divider,
 						  fan->samples);
 			break;

 		case hwmon_fan_fault:
 			err = regmap_read(fan->regmap, tacho->reg, &regval);
 			if (err)
 				return err;

 			*val = MLXREG_FAN_GET_FAULT(regval, tacho->mask);
 			break;

 		default:
 			return -EOPNOTSUPP;
 		}
 		break;

 	case hwmon_pwm:
 		switch (attr) {
 		case hwmon_pwm_input:
 			err = regmap_read(fan->regmap, fan->pwm.reg, &regval);
 			if (err)
 				return err;

 			*val = regval;
 			break;

 		default:
 			return -EOPNOTSUPP;
 		}
 		break;

 	default:
 		return -EOPNOTSUPP;
 	}

 	return 0;
 }

 static int
 mlxreg_fan_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
 		 int channel, long val)
 {
 	struct mlxreg_fan *fan = dev_get_drvdata(dev);

 	switch (type) {
 	case hwmon_pwm:
 		switch (attr) {
 		case hwmon_pwm_input:
 			if (val < MLXREG_FAN_MIN_DUTY ||
 			    val > MLXREG_FAN_MAX_DUTY)
 				return -EINVAL;
 			return regmap_write(fan->regmap, fan->pwm.reg, val);
 		default:
 			return -EOPNOTSUPP;
 		}
 		break;

 	default:
 		return -EOPNOTSUPP;
 	}

 	return -EOPNOTSUPP;
 }

 static umode_t
 mlxreg_fan_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
 		      int channel)
 {
 	switch (type) {
 	case hwmon_fan:
 		if (!(((struct mlxreg_fan *)data)->tacho[channel].connected))
 			return 0;

 		switch (attr) {
 		case hwmon_fan_input:
 		case hwmon_fan_fault:
 			return 0444;
 		default:
 			break;
 		}
 		break;

 	case hwmon_pwm:
 		if (!(((struct mlxreg_fan *)data)->pwm.connected))
 			return 0;

 		switch (attr) {
 		case hwmon_pwm_input:
 			return 0644;
 		default:
 			break;
 		}
 		break;

 	default:
 		break;
 	}

 	return 0;
 }

 static const struct hwmon_channel_info *mlxreg_fan_hwmon_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_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_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT),
 	HWMON_CHANNEL_INFO(pwm,
 			   HWMON_PWM_INPUT),
 	NULL
 };

 static const struct hwmon_ops mlxreg_fan_hwmon_hwmon_ops = {
 	.is_visible = mlxreg_fan_is_visible,
 	.read = mlxreg_fan_read,
 	.write = mlxreg_fan_write,
 };

 static const struct hwmon_chip_info mlxreg_fan_hwmon_chip_info = {
 	.ops = &mlxreg_fan_hwmon_hwmon_ops,
 	.info = mlxreg_fan_hwmon_info,
 };

 static int mlxreg_fan_get_max_state(struct thermal_cooling_device *cdev,
 				    unsigned long *state)
 {
 	*state = MLXREG_FAN_MAX_STATE;
 	return 0;
 }

 static int mlxreg_fan_get_cur_state(struct thermal_cooling_device *cdev,
 				    unsigned long *state)

 {
 	struct mlxreg_fan *fan = cdev->devdata;
 	u32 regval;
 	int err;

 	err = regmap_read(fan->regmap, fan->pwm.reg, &regval);
 	if (err) {
 		dev_err(fan->dev, "Failed to query PWM duty\n");
 		return err;
 	}

 	*state = MLXREG_FAN_PWM_DUTY2STATE(regval);

 	return 0;
 }

 static int mlxreg_fan_set_cur_state(struct thermal_cooling_device *cdev,
 				    unsigned long state)

 {
 	struct mlxreg_fan *fan = cdev->devdata;
 	unsigned long cur_state;
 	int i, config = 0;
 	u32 regval;
 	int err;

 	/*
 	 * Verify if this request is for changing allowed FAN dynamical
 	 * minimum. If it is - update cooling levels accordingly and update
 	 * state, if current state is below the newly requested minimum state.
 	 * For example, if current state is 5, and minimal state is to be
 	 * changed from 4 to 6, fan->cooling_levels[0 to 5] will be changed all
 	 * from 4 to 6. And state 5 (fan->cooling_levels[4]) should be
 	 * overwritten.
 	 */
 	if (state >= MLXREG_FAN_SPEED_MIN && state <= MLXREG_FAN_SPEED_MAX) {
 		/*
 		 * This is configuration change, which is only supported through sysfs.
 		 * For configuration non-zero value is to be returned to avoid thermal
 		 * statistics update.
 		 */
 		config = 1;
 		state -= MLXREG_FAN_MAX_STATE;
 		for (i = 0; i < state; i++)
 			fan->cooling_levels[i] = state;
 		for (i = state; i <= MLXREG_FAN_MAX_STATE; i++)
 			fan->cooling_levels[i] = i;

 		err = regmap_read(fan->regmap, fan->pwm.reg, &regval);
 		if (err) {
 			dev_err(fan->dev, "Failed to query PWM duty\n");
 			return err;
 		}

 		cur_state = MLXREG_FAN_PWM_DUTY2STATE(regval);
 		if (state < cur_state)
 			return config;

 		state = cur_state;
 	}

 	if (state > MLXREG_FAN_MAX_STATE)
 		return -EINVAL;

 	/* Normalize the state to the valid speed range. */
 	state = fan->cooling_levels[state];
 	err = regmap_write(fan->regmap, fan->pwm.reg,
 			   MLXREG_FAN_PWM_STATE2DUTY(state));
 	if (err) {
 		dev_err(fan->dev, "Failed to write PWM duty\n");
 		return err;
 	}
 	return config;
 }

 static const struct thermal_cooling_device_ops mlxreg_fan_cooling_ops = {
 	.get_max_state	= mlxreg_fan_get_max_state,
 	.get_cur_state	= mlxreg_fan_get_cur_state,
 	.set_cur_state	= mlxreg_fan_set_cur_state,
 };

 static int mlxreg_fan_connect_verify(struct mlxreg_fan *fan,
 				     struct mlxreg_core_data *data)
 {
 	u32 regval;
 	int err;

 	err = regmap_read(fan->regmap, data->capability, &regval);
 	if (err) {
 		dev_err(fan->dev, "Failed to query capability register 0x%08x\n",
 			data->capability);
 		return err;
 	}

 	return !!(regval & data->bit);
 }

 static int mlxreg_fan_speed_divider_get(struct mlxreg_fan *fan,
 					struct mlxreg_core_data *data)
 {
 	u32 regval;
 	int err;

 	err = regmap_read(fan->regmap, data->capability, &regval);
 	if (err) {
 		dev_err(fan->dev, "Failed to query capability register 0x%08x\n",
 			data->capability);
 		return err;
 	}

 	/*
 	 * Set divider value according to the capability register, in case it
 	 * contains valid value. Otherwise use default value. The purpose of
 	 * this validation is to protect against the old hardware, in which
 	 * this register can return zero.
 	 */
 	if (regval > 0 && regval <= MLXREG_FAN_TACHO_DIV_SCALE_MAX)
 		fan->divider = regval * MLXREG_FAN_TACHO_DIV_MIN;

 	return 0;
 }

 static int mlxreg_fan_config(struct mlxreg_fan *fan,
 			     struct mlxreg_core_platform_data *pdata)
 {
 	struct mlxreg_core_data *data = pdata->data;
 	int tacho_num = 0, tacho_avail = 0, i;
 	bool configured = false;
 	int err;

 	fan->samples = MLXREG_FAN_TACHO_SAMPLES_PER_PULSE_DEF;
 	fan->divider = MLXREG_FAN_TACHO_DIV_DEF;
 	for (i = 0; i < pdata->counter; i++, data++) {
 		if (strnstr(data->label, "tacho", sizeof(data->label))) {
 			if (tacho_num == MLXREG_FAN_MAX_TACHO) {
 				dev_err(fan->dev, "too many tacho entries: %s\n",
 					data->label);
 				return -EINVAL;
 			}

 			if (data->capability) {
 				err = mlxreg_fan_connect_verify(fan, data);
 				if (err < 0)
 					return err;
 				else if (!err) {
 					tacho_num++;
 					continue;
 				}
 			}

 			fan->tacho[tacho_num].reg = data->reg;
 			fan->tacho[tacho_num].mask = data->mask;
 			fan->tacho[tacho_num].prsnt = data->reg_prsnt;
 			fan->tacho[tacho_num++].connected = true;
 			tacho_avail++;
 		} else if (strnstr(data->label, "pwm", sizeof(data->label))) {
 			if (fan->pwm.connected) {
 				dev_err(fan->dev, "duplicate pwm entry: %s\n",
 					data->label);
 				return -EINVAL;
 			}
 			fan->pwm.reg = data->reg;
 			fan->pwm.connected = true;
 		} else if (strnstr(data->label, "conf", sizeof(data->label))) {
 			if (configured) {
 				dev_err(fan->dev, "duplicate conf entry: %s\n",
 					data->label);
 				return -EINVAL;
 			}
 			/* Validate that conf parameters are not zeros. */
 			if (!data->mask && !data->bit && !data->capability) {
 				dev_err(fan->dev, "invalid conf entry params: %s\n",
 					data->label);
 				return -EINVAL;
 			}
 			if (data->capability) {
 				err = mlxreg_fan_speed_divider_get(fan, data);
 				if (err)
 					return err;
 			} else {
 				if (data->mask)
 					fan->samples = data->mask;
 				if (data->bit)
 					fan->divider = data->bit;
 			}
 			configured = true;
 		} else {
 			dev_err(fan->dev, "invalid label: %s\n", data->label);
 			return -EINVAL;
 		}
 	}

 	if (pdata->capability) {
 		int drwr_avail;
 		u32 regval;

 		/* Obtain the number of FAN drawers, supported by system. */
 		err = regmap_read(fan->regmap, pdata->capability, &regval);
 		if (err) {
 			dev_err(fan->dev, "Failed to query capability register 0x%08x\n",
 				pdata->capability);
 			return err;
 		}

 		drwr_avail = hweight32(regval);
 		if (!tacho_avail || !drwr_avail || tacho_avail < drwr_avail) {
 			dev_err(fan->dev, "Configuration is invalid: drawers num %d tachos num %d\n",
 				drwr_avail, tacho_avail);
 			return -EINVAL;
 		}

 		/* Set the number of tachometers per one drawer. */
 		fan->tachos_per_drwr = tacho_avail / drwr_avail;
 	}

 	/* Init cooling levels per PWM state. */
 	for (i = 0; i < MLXREG_FAN_SPEED_MIN_LEVEL; i++)
 		fan->cooling_levels[i] = MLXREG_FAN_SPEED_MIN_LEVEL;
 	for (i = MLXREG_FAN_SPEED_MIN_LEVEL; i <= MLXREG_FAN_MAX_STATE; i++)
 		fan->cooling_levels[i] = i;

 	return 0;
 }

 static int mlxreg_fan_probe(struct platform_device *pdev)
 {
 	struct mlxreg_core_platform_data *pdata;
 	struct device *dev = &pdev->dev;
 	struct mlxreg_fan *fan;
 	struct device *hwm;
 	int err;

 	pdata = dev_get_platdata(dev);
 	if (!pdata) {
 		dev_err(dev, "Failed to get platform data.\n");
 		return -EINVAL;
 	}

 	fan = devm_kzalloc(dev, sizeof(*fan), GFP_KERNEL);
 	if (!fan)
 		return -ENOMEM;

 	fan->dev = dev;
 	fan->regmap = pdata->regmap;

 	err = mlxreg_fan_config(fan, pdata);
 	if (err)
 		return err;

 	hwm = devm_hwmon_device_register_with_info(dev, "mlxreg_fan",
 						   fan,
 						   &mlxreg_fan_hwmon_chip_info,
 						   NULL);
 	if (IS_ERR(hwm)) {
 		dev_err(dev, "Failed to register hwmon device\n");
 		return PTR_ERR(hwm);
 	}

 	if (IS_REACHABLE(CONFIG_THERMAL)) {
 		fan->cdev = devm_thermal_of_cooling_device_register(dev,
 			NULL, "mlxreg_fan", fan, &mlxreg_fan_cooling_ops);
 		if (IS_ERR(fan->cdev)) {
 			dev_err(dev, "Failed to register cooling device\n");
 			return PTR_ERR(fan->cdev);
 		}
 	}

 	return 0;
 }

 static struct platform_driver mlxreg_fan_driver = {
 	.driver = {
 	    .name = "mlxreg-fan",
 	},
 	.probe = mlxreg_fan_probe,
 };

 module_platform_driver(mlxreg_fan_driver);

 MODULE_AUTHOR("Vadim Pasternak <vadimp@mellanox.com>");
 MODULE_DESCRIPTION("Mellanox FAN driver");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:mlxreg-fan");
	// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
	//
	// Copyright (c) 2018 Mellanox Technologies. All rights reserved.
	// Copyright (c) 2018 Vadim Pasternak <vadimp@mellanox.com>

	#include <linux/bitops.h>
	#include <linux/device.h>
	#include <linux/hwmon.h>
	#include <linux/module.h>
	#include <linux/platform_data/mlxreg.h>
	#include <linux/platform_device.h>
	#include <linux/regmap.h>
	#include <linux/thermal.h>

	#define MLXREG_FAN_MAX_TACHO 12
	#define MLXREG_FAN_MAX_STATE 10
	#define MLXREG_FAN_MIN_DUTY 51 /* 20% */
	#define MLXREG_FAN_MAX_DUTY 255 /* 100% */
	/*
	* Minimum and maximum FAN allowed speed in percent: from 20% to 100%. Values
	* MLXREG_FAN_MAX_STATE + x, where x is between 2 and 10 are used for
	* setting FAN speed dynamic minimum. For example, if value is set to 14 (40%)
	* cooling levels vector will be set to 4, 4, 4, 4, 4, 5, 6, 7, 8, 9, 10 to
	* introduce PWM speed in percent: 40, 40, 40, 40, 40, 50, 60. 70, 80, 90, 100.
	*/
	#define MLXREG_FAN_SPEED_MIN (MLXREG_FAN_MAX_STATE + 2)
	#define MLXREG_FAN_SPEED_MAX (MLXREG_FAN_MAX_STATE * 2)
	#define MLXREG_FAN_SPEED_MIN_LEVEL 2 /* 20 percent */
	#define MLXREG_FAN_TACHO_SAMPLES_PER_PULSE_DEF 44
	#define MLXREG_FAN_TACHO_DIV_MIN 283
	#define MLXREG_FAN_TACHO_DIV_DEF (MLXREG_FAN_TACHO_DIV_MIN * 4)
	#define MLXREG_FAN_TACHO_DIV_SCALE_MAX 64
	/*
	* FAN datasheet defines the formula for RPM calculations as RPM = 15/t-high.
	* The logic in a programmable device measures the time t-high by sampling the
	* tachometer every t-sample (with the default value 11.32 uS) and increment
	* a counter (N) as long as the pulse has not change:
	* RPM = 15 / (t-sample * (K + Regval)), where:
	* Regval: is the value read from the programmable device register;
	* - 0xff - represents tachometer fault;
	* - 0xfe - represents tachometer minimum value , which is 4444 RPM;
	* - 0x00 - represents tachometer maximum value , which is 300000 RPM;
	* K: is 44 and it represents the minimum allowed samples per pulse;
	* N: is equal K + Regval;
	* In order to calculate RPM from the register value the following formula is
	* used: RPM = 15 / ((Regval + K) * 11.32) * 10^(-6)), which in the
	* default case is modified to:
	* RPM = 15000000 * 100 / ((Regval + 44) * 1132);
	* - for Regval 0x00, RPM will be 15000000 * 100 / (44 * 1132) = 30115;
	* - for Regval 0xfe, RPM will be 15000000 * 100 / ((254 + 44) * 1132) = 4446;
	* In common case the formula is modified to:
	* RPM = 15000000 * 100 / ((Regval + samples) * divider).
	*/
	#define MLXREG_FAN_GET_RPM(rval, d, s) (DIV_ROUND_CLOSEST(15000000 * 100, \
	((rval) + (s)) * (d)))
	#define MLXREG_FAN_GET_FAULT(val, mask) ((val) == (mask))
	#define MLXREG_FAN_PWM_DUTY2STATE(duty) (DIV_ROUND_CLOSEST((duty) * \
	MLXREG_FAN_MAX_STATE, \
	MLXREG_FAN_MAX_DUTY))
	#define MLXREG_FAN_PWM_STATE2DUTY(stat) (DIV_ROUND_CLOSEST((stat) * \
	MLXREG_FAN_MAX_DUTY, \
	MLXREG_FAN_MAX_STATE))

	/*
	* struct mlxreg_fan_tacho - tachometer data (internal use):
	*
	* @connected: indicates if tachometer is connected;
	* @reg: register offset;
	* @mask: fault mask;
	* @prsnt: present register offset;
	*/
	struct mlxreg_fan_tacho {
	bool connected;
	u32 reg;
	u32 mask;
	u32 prsnt;
	};

	/*
	* struct mlxreg_fan_pwm - PWM data (internal use):
	*
	* @connected: indicates if PWM is connected;
	* @reg: register offset;
	*/
	struct mlxreg_fan_pwm {
	bool connected;
	u32 reg;
	};

	/*
	* struct mlxreg_fan - private data (internal use):
	*
	* @dev: basic device;
	* @regmap: register map of parent device;
	* @tacho: tachometer data;
	* @pwm: PWM data;
	* @tachos_per_drwr - number of tachometers per drawer;
	* @samples: minimum allowed samples per pulse;
	* @divider: divider value for tachometer RPM calculation;
	* @cooling: cooling device levels;
	* @cdev: cooling device;
	*/
	struct mlxreg_fan {
	struct device *dev;
	void *regmap;
	struct mlxreg_core_platform_data *pdata;
	struct mlxreg_fan_tacho tacho[MLXREG_FAN_MAX_TACHO];
	struct mlxreg_fan_pwm pwm;
	int tachos_per_drwr;
	int samples;
	int divider;
	u8 cooling_levels[MLXREG_FAN_MAX_STATE + 1];
	struct thermal_cooling_device *cdev;
	};

	static int
	mlxreg_fan_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
	int channel, long *val)
	{
	struct mlxreg_fan *fan = dev_get_drvdata(dev);
	struct mlxreg_fan_tacho *tacho;
	u32 regval;
	int err;

	switch (type) {
	case hwmon_fan:
	tacho = &fan->tacho[channel];
	switch (attr) {
	case hwmon_fan_input:
	/*
	* Check FAN presence: FAN related bit in presence register is one,
	* if FAN is physically connected, zero - otherwise.
	*/
	if (tacho->prsnt && fan->tachos_per_drwr) {
	err = regmap_read(fan->regmap, tacho->prsnt, &regval);
	if (err)
	return err;

	/*
	* Map channel to presence bit - drawer can be equipped with
	* one or few FANs, while presence is indicated per drawer.
	*/
	if (BIT(channel / fan->tachos_per_drwr) & regval) {
	/* FAN is not connected - return zero for FAN speed. */
	*val = 0;
	return 0;
	}
	}

	err = regmap_read(fan->regmap, tacho->reg, &regval);
	if (err)
	return err;

	*val = MLXREG_FAN_GET_RPM(regval, fan->divider,
	fan->samples);
	break;

	case hwmon_fan_fault:
	err = regmap_read(fan->regmap, tacho->reg, &regval);
	if (err)
	return err;

	*val = MLXREG_FAN_GET_FAULT(regval, tacho->mask);
	break;

	default:
	return -EOPNOTSUPP;
	}
	break;

	case hwmon_pwm:
	switch (attr) {
	case hwmon_pwm_input:
	err = regmap_read(fan->regmap, fan->pwm.reg, &regval);
	if (err)
	return err;

	*val = regval;
	break;

	default:
	return -EOPNOTSUPP;
	}
	break;

	default:
	return -EOPNOTSUPP;
	}

	return 0;
	}

	static int
	mlxreg_fan_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
	int channel, long val)
	{
	struct mlxreg_fan *fan = dev_get_drvdata(dev);

	switch (type) {
	case hwmon_pwm:
	switch (attr) {
	case hwmon_pwm_input:
	if (val < MLXREG_FAN_MIN_DUTY \|\|
	val > MLXREG_FAN_MAX_DUTY)
	return -EINVAL;
	return regmap_write(fan->regmap, fan->pwm.reg, val);
	default:
	return -EOPNOTSUPP;
	}
	break;

	default:
	return -EOPNOTSUPP;
	}

	return -EOPNOTSUPP;
	}

	static umode_t
	mlxreg_fan_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
	int channel)
	{
	switch (type) {
	case hwmon_fan:
	if (!(((struct mlxreg_fan *)data)->tacho[channel].connected))
	return 0;

	switch (attr) {
	case hwmon_fan_input:
	case hwmon_fan_fault:
	return 0444;
	default:
	break;
	}
	break;

	case hwmon_pwm:
	if (!(((struct mlxreg_fan *)data)->pwm.connected))
	return 0;

	switch (attr) {
	case hwmon_pwm_input:
	return 0644;
	default:
	break;
	}
	break;

	default:
	break;
	}

	return 0;
	}

	static const struct hwmon_channel_info *mlxreg_fan_hwmon_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_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_F_INPUT \| HWMON_F_FAULT,
	HWMON_F_INPUT \| HWMON_F_FAULT),
	HWMON_CHANNEL_INFO(pwm,
	HWMON_PWM_INPUT),
	NULL
	};

	static const struct hwmon_ops mlxreg_fan_hwmon_hwmon_ops = {
	.is_visible = mlxreg_fan_is_visible,
	.read = mlxreg_fan_read,
	.write = mlxreg_fan_write,
	};

	static const struct hwmon_chip_info mlxreg_fan_hwmon_chip_info = {
	.ops = &mlxreg_fan_hwmon_hwmon_ops,
	.info = mlxreg_fan_hwmon_info,
	};

	static int mlxreg_fan_get_max_state(struct thermal_cooling_device *cdev,
	unsigned long *state)
	{
	*state = MLXREG_FAN_MAX_STATE;
	return 0;
	}

	static int mlxreg_fan_get_cur_state(struct thermal_cooling_device *cdev,
	unsigned long *state)

	{
	struct mlxreg_fan *fan = cdev->devdata;
	u32 regval;
	int err;

	err = regmap_read(fan->regmap, fan->pwm.reg, &regval);
	if (err) {
	dev_err(fan->dev, "Failed to query PWM duty\n");
	return err;
	}

	*state = MLXREG_FAN_PWM_DUTY2STATE(regval);

	return 0;
	}

	static int mlxreg_fan_set_cur_state(struct thermal_cooling_device *cdev,
	unsigned long state)

	{
	struct mlxreg_fan *fan = cdev->devdata;
	unsigned long cur_state;
	int i, config = 0;
	u32 regval;
	int err;

	/*
	* Verify if this request is for changing allowed FAN dynamical
	* minimum. If it is - update cooling levels accordingly and update
	* state, if current state is below the newly requested minimum state.
	* For example, if current state is 5, and minimal state is to be
	* changed from 4 to 6, fan->cooling_levels[0 to 5] will be changed all
	* from 4 to 6. And state 5 (fan->cooling_levels[4]) should be
	* overwritten.
	*/
	if (state >= MLXREG_FAN_SPEED_MIN && state <= MLXREG_FAN_SPEED_MAX) {
	/*
	* This is configuration change, which is only supported through sysfs.
	* For configuration non-zero value is to be returned to avoid thermal
	* statistics update.
	*/
	config = 1;
	state -= MLXREG_FAN_MAX_STATE;
	for (i = 0; i < state; i++)
	fan->cooling_levels[i] = state;
	for (i = state; i <= MLXREG_FAN_MAX_STATE; i++)
	fan->cooling_levels[i] = i;

	err = regmap_read(fan->regmap, fan->pwm.reg, &regval);
	if (err) {
	dev_err(fan->dev, "Failed to query PWM duty\n");
	return err;
	}

	cur_state = MLXREG_FAN_PWM_DUTY2STATE(regval);
	if (state < cur_state)
	return config;

	state = cur_state;
	}

	if (state > MLXREG_FAN_MAX_STATE)
	return -EINVAL;

	/* Normalize the state to the valid speed range. */
	state = fan->cooling_levels[state];
	err = regmap_write(fan->regmap, fan->pwm.reg,
	MLXREG_FAN_PWM_STATE2DUTY(state));
	if (err) {
	dev_err(fan->dev, "Failed to write PWM duty\n");
	return err;
	}
	return config;
	}

	static const struct thermal_cooling_device_ops mlxreg_fan_cooling_ops = {
	.get_max_state = mlxreg_fan_get_max_state,
	.get_cur_state = mlxreg_fan_get_cur_state,
	.set_cur_state = mlxreg_fan_set_cur_state,
	};

	static int mlxreg_fan_connect_verify(struct mlxreg_fan *fan,
	struct mlxreg_core_data *data)
	{
	u32 regval;
	int err;

	err = regmap_read(fan->regmap, data->capability, &regval);
	if (err) {
	dev_err(fan->dev, "Failed to query capability register 0x%08x\n",
	data->capability);
	return err;
	}

	return !!(regval & data->bit);
	}

	static int mlxreg_fan_speed_divider_get(struct mlxreg_fan *fan,
	struct mlxreg_core_data *data)
	{
	u32 regval;
	int err;

	err = regmap_read(fan->regmap, data->capability, &regval);
	if (err) {
	dev_err(fan->dev, "Failed to query capability register 0x%08x\n",
	data->capability);
	return err;
	}

	/*
	* Set divider value according to the capability register, in case it
	* contains valid value. Otherwise use default value. The purpose of
	* this validation is to protect against the old hardware, in which
	* this register can return zero.
	*/
	if (regval > 0 && regval <= MLXREG_FAN_TACHO_DIV_SCALE_MAX)
	fan->divider = regval * MLXREG_FAN_TACHO_DIV_MIN;

	return 0;
	}

	static int mlxreg_fan_config(struct mlxreg_fan *fan,
	struct mlxreg_core_platform_data *pdata)
	{
	struct mlxreg_core_data *data = pdata->data;
	int tacho_num = 0, tacho_avail = 0, i;
	bool configured = false;
	int err;

	fan->samples = MLXREG_FAN_TACHO_SAMPLES_PER_PULSE_DEF;
	fan->divider = MLXREG_FAN_TACHO_DIV_DEF;
	for (i = 0; i < pdata->counter; i++, data++) {
	if (strnstr(data->label, "tacho", sizeof(data->label))) {
	if (tacho_num == MLXREG_FAN_MAX_TACHO) {
	dev_err(fan->dev, "too many tacho entries: %s\n",
	data->label);
	return -EINVAL;
	}

	if (data->capability) {
	err = mlxreg_fan_connect_verify(fan, data);
	if (err < 0)
	return err;
	else if (!err) {
	tacho_num++;
	continue;
	}
	}

	fan->tacho[tacho_num].reg = data->reg;
	fan->tacho[tacho_num].mask = data->mask;
	fan->tacho[tacho_num].prsnt = data->reg_prsnt;
	fan->tacho[tacho_num++].connected = true;
	tacho_avail++;
	} else if (strnstr(data->label, "pwm", sizeof(data->label))) {
	if (fan->pwm.connected) {
	dev_err(fan->dev, "duplicate pwm entry: %s\n",
	data->label);
	return -EINVAL;
	}
	fan->pwm.reg = data->reg;
	fan->pwm.connected = true;
	} else if (strnstr(data->label, "conf", sizeof(data->label))) {
	if (configured) {
	dev_err(fan->dev, "duplicate conf entry: %s\n",
	data->label);
	return -EINVAL;
	}
	/* Validate that conf parameters are not zeros. */
	if (!data->mask && !data->bit && !data->capability) {
	dev_err(fan->dev, "invalid conf entry params: %s\n",
	data->label);
	return -EINVAL;
	}
	if (data->capability) {
	err = mlxreg_fan_speed_divider_get(fan, data);
	if (err)
	return err;
	} else {
	if (data->mask)
	fan->samples = data->mask;
	if (data->bit)
	fan->divider = data->bit;
	}
	configured = true;
	} else {
	dev_err(fan->dev, "invalid label: %s\n", data->label);
	return -EINVAL;
	}
	}

	if (pdata->capability) {
	int drwr_avail;
	u32 regval;

	/* Obtain the number of FAN drawers, supported by system. */
	err = regmap_read(fan->regmap, pdata->capability, &regval);
	if (err) {
	dev_err(fan->dev, "Failed to query capability register 0x%08x\n",
	pdata->capability);
	return err;
	}

	drwr_avail = hweight32(regval);
	if (!tacho_avail \|\| !drwr_avail \|\| tacho_avail < drwr_avail) {
	dev_err(fan->dev, "Configuration is invalid: drawers num %d tachos num %d\n",
	drwr_avail, tacho_avail);
	return -EINVAL;
	}

	/* Set the number of tachometers per one drawer. */
	fan->tachos_per_drwr = tacho_avail / drwr_avail;
	}

	/* Init cooling levels per PWM state. */
	for (i = 0; i < MLXREG_FAN_SPEED_MIN_LEVEL; i++)
	fan->cooling_levels[i] = MLXREG_FAN_SPEED_MIN_LEVEL;
	for (i = MLXREG_FAN_SPEED_MIN_LEVEL; i <= MLXREG_FAN_MAX_STATE; i++)
	fan->cooling_levels[i] = i;

	return 0;
	}

	static int mlxreg_fan_probe(struct platform_device *pdev)
	{
	struct mlxreg_core_platform_data *pdata;
	struct device *dev = &pdev->dev;
	struct mlxreg_fan *fan;
	struct device *hwm;
	int err;

	pdata = dev_get_platdata(dev);
	if (!pdata) {
	dev_err(dev, "Failed to get platform data.\n");
	return -EINVAL;
	}

	fan = devm_kzalloc(dev, sizeof(*fan), GFP_KERNEL);
	if (!fan)
	return -ENOMEM;

	fan->dev = dev;
	fan->regmap = pdata->regmap;

	err = mlxreg_fan_config(fan, pdata);
	if (err)
	return err;

	hwm = devm_hwmon_device_register_with_info(dev, "mlxreg_fan",
	fan,
	&mlxreg_fan_hwmon_chip_info,
	NULL);
	if (IS_ERR(hwm)) {
	dev_err(dev, "Failed to register hwmon device\n");
	return PTR_ERR(hwm);
	}

	if (IS_REACHABLE(CONFIG_THERMAL)) {
	fan->cdev = devm_thermal_of_cooling_device_register(dev,
	NULL, "mlxreg_fan", fan, &mlxreg_fan_cooling_ops);
	if (IS_ERR(fan->cdev)) {
	dev_err(dev, "Failed to register cooling device\n");
	return PTR_ERR(fan->cdev);
	}
	}

	return 0;
	}

	static struct platform_driver mlxreg_fan_driver = {
	.driver = {
	.name = "mlxreg-fan",
	},
	.probe = mlxreg_fan_probe,
	};

	module_platform_driver(mlxreg_fan_driver);

	MODULE_AUTHOR("Vadim Pasternak <vadimp@mellanox.com>");
	MODULE_DESCRIPTION("Mellanox FAN driver");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:mlxreg-fan");