Date:   Wed, 16 Nov 2022 02:28:44 +0530
From:   Naresh Solanki <naresh.solanki@...ements.com>
To:     Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Cc:     devicetree@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
        Jean Delvare <jdelvare@...e.com>,
        Thierry Reding <thierry.reding@...il.com>,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>,
        Marcello Sylvester Bauer <sylv@...v.io>,
        linux-pwm@...r.kernel.org
Subject: Re: [PATCH v5 3/3] hwmon: (max6639) Change from pdata to dt
 configuration

Hi Uwe,

On 15-11-2022 10:31 pm, Uwe Kleine-König wrote:
> Hello,
> 
> On Tue, Nov 15, 2022 at 01:20:05PM +0100, Naresh Solanki wrote:
>> max6639_platform_data is not used by any in-kernel driver and does not
>> address the MAX6639 fans separately.
>> Move to device tree configuration with explicit properties to configure
>> each fan.
> 
> My overall impression is that this patch mixes too much things. IMHO it
> should be split in (at least)
> 
>   - Add dt support
>   - Drop platform support
>   - Add PWM provider support
>   - Make use of the PWM API
> 
> maybe also add the 2nd PWM in a separate step.
> 
> Some more comments inline.
> 
>> Non-DT platform can still use this module with its default
>> configuration.
>>
>> Signed-off-by: Marcello Sylvester Bauer <sylv@...v.io>
>> Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
>> ---
>>   drivers/hwmon/Kconfig   |   1 +
>>   drivers/hwmon/max6639.c | 465 +++++++++++++++++++++++++++++++++-------
>>   2 files changed, 392 insertions(+), 74 deletions(-)
>>
>> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
>> index 5695b266abcf..ad1f6742ca50 100644
>> --- a/drivers/hwmon/Kconfig
>> +++ b/drivers/hwmon/Kconfig
>> @@ -1106,6 +1106,7 @@ config SENSORS_MAX6621
>>   config SENSORS_MAX6639
>>   	tristate "Maxim MAX6639 sensor chip"
>>   	depends on I2C
>> +	depends on PWM
>>   	help
>>   	  If you say yes here you get support for the MAX6639
>>   	  sensor chips.
>> diff --git a/drivers/hwmon/max6639.c b/drivers/hwmon/max6639.c
>> index 9b895402c80d..d1ae77e8f72e 100644
>> --- a/drivers/hwmon/max6639.c
>> +++ b/drivers/hwmon/max6639.c
>> @@ -19,7 +19,7 @@
>>   #include <linux/hwmon-sysfs.h>
>>   #include <linux/err.h>
>>   #include <linux/mutex.h>
>> -#include <linux/platform_data/max6639.h>
> 
> This file is now unused and can be dropped.
Sure in next version.
> 
>> +#include <linux/pwm.h>
>>   
>>   /* Addresses to scan */
>>   static const unsigned short normal_i2c[] = { 0x2c, 0x2e, 0x2f, I2C_CLIENT_END };
>> @@ -54,11 +54,20 @@ static const unsigned short normal_i2c[] = { 0x2c, 0x2e, 0x2f, I2C_CLIENT_END };
>>   #define MAX6639_GCONFIG_PWM_FREQ_HI		0x08
>>   
>>   #define MAX6639_FAN_CONFIG1_PWM			0x80
>> -
>> +#define MAX6639_REG_FAN_CONFIG2a_PWM_POL	0x02
>>   #define MAX6639_FAN_CONFIG3_THERM_FULL_SPEED	0x40
>> +#define MAX6639_FAN_CONFIG3_FREQ_MASK		0x03
>> +#define MAX6639_REG_TARGTDUTY_SLOT		120
>>   
>> +/* Tach supported range. This internally controls tach frequency */
>>   static const int rpm_ranges[] = { 2000, 4000, 8000, 16000 };
>>   
>> +/* Supported PWM frequency */
>> +static const unsigned int freq_table[] = { 20, 33, 50, 100, 5000, 8333, 12500,
>> +					25000 };
> 
> I would have put these in a single line, or one line per freq, or at
> least aligned the last value such that it is at a higher column than the
> opening {.
Sure will align.
> 
>> +
>> +
>> +
> 
> Three empty lines? One or two only should do it.
Oh. Will correct this in next version.
> 
>>   #define FAN_FROM_REG(val, rpm_range)	((val) == 0 || (val) == 255 ? \
>>   				0 : (rpm_ranges[rpm_range] * 30) / (val))
>>   #define TEMP_LIMIT_TO_REG(val)	clamp_val((val) / 1000, 0, 255)
>> @@ -76,20 +85,24 @@ struct max6639_data {
>>   	u16 temp[2];		/* Temperature, in 1/8 C, 0..255 C */
>>   	bool temp_fault[2];	/* Detected temperature diode failure */
>>   	u8 fan[2];		/* Register value: TACH count for fans >=30 */
>> +	struct pwm_device	*pwmd[2]; /* max6639 has two pwm device */
>> +	u32 target_rpm[2];
>> +	u32 max_rpm[2];
>> +
>>   	u8 status;		/* Detected channel alarms and fan failures */
>>   
>>   	/* Register values only written to */
>> -	u8 pwm[2];		/* Register value: Duty cycle 0..120 */
>>   	u8 temp_therm[2];	/* THERM Temperature, 0..255 C (->_max) */
>>   	u8 temp_alert[2];	/* ALERT Temperature, 0..255 C (->_crit) */
>>   	u8 temp_ot[2];		/* OT Temperature, 0..255 C (->_emergency) */
>>   
>>   	/* Register values initialized only once */
>> -	u8 ppr;			/* Pulses per rotation 0..3 for 1..4 ppr */
>> -	u8 rpm_range;		/* Index in above rpm_ranges table */
>> -
>> +	u8 ppr[2];		/* Pulses per rotation 0..3 for 1..4 ppr */
>> +	u8 rpm_range[2];	/* Index in above rpm_ranges table */
>>   	/* Optional regulator for FAN supply */
>>   	struct regulator *reg;
>> +	/* max6639 pwm chip */
>> +	struct pwm_chip chip;
>>   };
>>   
>>   static struct max6639_data *max6639_update_device(struct device *dev)
>> @@ -280,8 +293,12 @@ static ssize_t pwm_show(struct device *dev, struct device_attribute *dev_attr,
>>   {
>>   	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
>>   	struct max6639_data *data = dev_get_drvdata(dev);
>> +	struct pwm_state state;
>> +
>> +	pwm_get_state(data->pwmd[attr->index], &state);
>> +
>> +	return sprintf(buf, "%d\n", pwm_get_relative_duty_cycle(&state, 255));
>>   
>> -	return sprintf(buf, "%d\n", data->pwm[attr->index] * 255 / 120);
>>   }
>>   
>>   static ssize_t pwm_store(struct device *dev,
>> @@ -290,9 +307,9 @@ static ssize_t pwm_store(struct device *dev,
>>   {
>>   	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
>>   	struct max6639_data *data = dev_get_drvdata(dev);
>> -	struct i2c_client *client = data->client;
>>   	unsigned long val;
>>   	int res;
>> +	struct pwm_state state;
>>   
>>   	res = kstrtoul(buf, 10, &val);
>>   	if (res)
>> @@ -300,12 +317,12 @@ static ssize_t pwm_store(struct device *dev,
>>   
>>   	val = clamp_val(val, 0, 255);
>>   
>> -	mutex_lock(&data->update_lock);
>> -	data->pwm[attr->index] = (u8)(val * 120 / 255);
>> -	i2c_smbus_write_byte_data(client,
>> -				  MAX6639_REG_TARGTDUTY(attr->index),
>> -				  data->pwm[attr->index]);
>> -	mutex_unlock(&data->update_lock);
>> +	pwm_get_state(data->pwmd[attr->index], &state);
>> +	pwm_set_relative_duty_cycle(&state, val, 255);
>> +	res = pwm_apply_state(data->pwmd[attr->index], &state);
>> +	if (res)
>> +		return res;
>> +
>>   	return count;
>>   }
>>   
>> @@ -319,7 +336,7 @@ static ssize_t fan_input_show(struct device *dev,
>>   		return PTR_ERR(data);
>>   
>>   	return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan[attr->index],
>> -		       data->rpm_range));
>> +		       data->rpm_range[attr->index]));
>>   }
>>   
>>   static ssize_t alarm_show(struct device *dev,
>> @@ -386,29 +403,41 @@ static struct attribute *max6639_attrs[] = {
>>   ATTRIBUTE_GROUPS(max6639);
>>   
>>   /*
>> - *  returns respective index in rpm_ranges table
>> - *  1 by default on invalid range
>> + *  Get respective index in rpm_ranges table
>>    */
>> -static int rpm_range_to_reg(int range)
>> +static int rpm_range_to_index(struct device *dev, u8 *index, int rpm)
>>   {
>> -	int i;
>> -
>> -	for (i = 0; i < ARRAY_SIZE(rpm_ranges); i++) {
>> -		if (rpm_ranges[i] == range)
>> -			return i;
>> +	if (rpm < 0)
>> +		return -EINVAL;
>> +
>> +	/* Set index based on chip support */
>> +	switch (rpm) {
>> +	case 0 ... 2000:
>> +		*index = 0;
>> +		break;
>> +	case 2001 ... 4000:
>> +		*index = 1;
>> +		break;
>> +	case 4001 ... 8000:
>> +		*index = 2;
>> +		break;
>> +	case 8001 ... 16000:
>> +		*index = 3;
>> +		break;
>> +	default:
>> +		/* Use max range for higher RPM */
>> +		dev_warn(dev,
>> +		    "RPM higher than supported range. Default to 16000 RPM");
>> +		*index = 3;
>>   	}
>> -
>> -	return 1; /* default: 4000 RPM */
>> +	return 0;
>>   }
>>   
>>   static int max6639_init_client(struct i2c_client *client,
>>   			       struct max6639_data *data)
>>   {
>> -	struct max6639_platform_data *max6639_info =
>> -		dev_get_platdata(&client->dev);
>> -	int i;
>> -	int rpm_range = 1; /* default: 4000 RPM */
>> -	int err;
>> +	int i, err;
>> +	struct pwm_state state;
>>   
>>   	/* Reset chip to default values, see below for GCONFIG setup */
>>   	err = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
>> @@ -416,51 +445,29 @@ static int max6639_init_client(struct i2c_client *client,
>>   	if (err)
>>   		goto exit;
>>   
>> -	/* Fans pulse per revolution is 2 by default */
>> -	if (max6639_info && max6639_info->ppr > 0 &&
>> -			max6639_info->ppr < 5)
>> -		data->ppr = max6639_info->ppr;
>> -	else
>> -		data->ppr = 2;
>> -	data->ppr -= 1;
>> -
>> -	if (max6639_info)
>> -		rpm_range = rpm_range_to_reg(max6639_info->rpm_range);
>> -	data->rpm_range = rpm_range;
>> -
>>   	for (i = 0; i < 2; i++) {
>>   
>>   		/* Set Fan pulse per revolution */
>> -		err = i2c_smbus_write_byte_data(client,
>> -				MAX6639_REG_FAN_PPR(i),
>> -				data->ppr << 6);
>> +		err = i2c_smbus_write_byte_data(client,	MAX6639_REG_FAN_PPR(i),
>> +						data->ppr[i] << 6);
>>   		if (err)
>>   			goto exit;
>>   
>>   		/* Fans config PWM, RPM */
>>   		err = i2c_smbus_write_byte_data(client,
>> -			MAX6639_REG_FAN_CONFIG1(i),
>> -			MAX6639_FAN_CONFIG1_PWM | rpm_range);
>> -		if (err)
>> -			goto exit;
>> -
>> -		/* Fans PWM polarity high by default */
>> -		if (max6639_info && max6639_info->pwm_polarity == 0)
>> -			err = i2c_smbus_write_byte_data(client,
>> -				MAX6639_REG_FAN_CONFIG2a(i), 0x00);
>> -		else
>> -			err = i2c_smbus_write_byte_data(client,
>> -				MAX6639_REG_FAN_CONFIG2a(i), 0x02);
>> +						MAX6639_REG_FAN_CONFIG1(i),
>> +						MAX6639_FAN_CONFIG1_PWM |
>> +						data->rpm_range[i]);
>>   		if (err)
>>   			goto exit;
>>   
>>   		/*
>> -		 * /THERM full speed enable,
>> +		 * /THERM full speed disable,
>>   		 * PWM frequency 25kHz, see also GCONFIG below
>>   		 */
>>   		err = i2c_smbus_write_byte_data(client,
>> -			MAX6639_REG_FAN_CONFIG3(i),
>> -			MAX6639_FAN_CONFIG3_THERM_FULL_SPEED | 0x03);
>> +						MAX6639_REG_FAN_CONFIG3(i),
>> +						0x03);
>>   		if (err)
>>   			goto exit;
>>   
>> @@ -469,31 +476,35 @@ static int max6639_init_client(struct i2c_client *client,
>>   		data->temp_alert[i] = 90;
>>   		data->temp_ot[i] = 100;
>>   		err = i2c_smbus_write_byte_data(client,
>> -				MAX6639_REG_THERM_LIMIT(i),
>> -				data->temp_therm[i]);
>> +						MAX6639_REG_THERM_LIMIT(i),
>> +						data->temp_therm[i]);
>>   		if (err)
>>   			goto exit;
>>   		err = i2c_smbus_write_byte_data(client,
>> -				MAX6639_REG_ALERT_LIMIT(i),
>> -				data->temp_alert[i]);
>> +						MAX6639_REG_ALERT_LIMIT(i),
>> +						data->temp_alert[i]);
>>   		if (err)
>>   			goto exit;
>>   		err = i2c_smbus_write_byte_data(client,
>> -				MAX6639_REG_OT_LIMIT(i), data->temp_ot[i]);
>> +						MAX6639_REG_OT_LIMIT(i),
>> +						data->temp_ot[i]);
>>   		if (err)
>>   			goto exit;
>>   
>> -		/* PWM 120/120 (i.e. 100%) */
>> -		data->pwm[i] = 120;
>> -		err = i2c_smbus_write_byte_data(client,
>> -				MAX6639_REG_TARGTDUTY(i), data->pwm[i]);
>> +		/* Configure PWM controller */
>> +		pwm_get_state(data->pwmd[i], &state);
>> +		pwm_set_relative_duty_cycle(&state, data->target_rpm[i],
>> +					    data->max_rpm[i]);
>> +		err = pwm_apply_state(data->pwmd[i], &state);
>>   		if (err)
>>   			goto exit;
>> +
>>   	}
>>   	/* Start monitoring */
>>   	err = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
>>   		MAX6639_GCONFIG_DISABLE_TIMEOUT | MAX6639_GCONFIG_CH2_LOCAL |
>>   		MAX6639_GCONFIG_PWM_FREQ_HI);
>> +
>>   exit:
>>   	return err;
>>   }
>> @@ -524,12 +535,276 @@ static void max6639_regulator_disable(void *data)
>>   	regulator_disable(data);
>>   }
>>   
>> +static int max6639_probe_child_from_dt(struct i2c_client *client,
>> +				      struct device_node *child,
>> +				      struct max6639_data *data)
>> +
>> +{
>> +	struct device *dev = &client->dev;
>> +	u32 i, maxrpm;
>> +	int val, err;
>> +
>> +	err = of_property_read_u32(child, "reg", &i);
>> +	if (err) {
>> +		dev_err(dev, "missing reg property of %pOFn\n", child);
>> +		return err;
>> +	}
>> +
>> +	if (i >= 2) {
>> +		dev_err(dev, "invalid reg %d of %pOFn\n", i, child);
>> +		return -EINVAL;
>> +	}
>> +
>> +	err = of_property_read_u32(child, "pulses-per-revolution", &val);
>> +	if (err) {
>> +		dev_err(dev, "missing pulses-per-revolution property of %pOFn",
>> +			child);
>> +		return err;
>> +	}
>> +
>> +	if (val < 0 || val > 5) {
>> +		dev_err(dev, "invalid pulses-per-revolution %d of %pOFn\n", val,
>> +			child);
>> +		return -EINVAL;
>> +	}
>> +	data->ppr[i] = val;
>> +
>> +	err = of_property_read_u32(child, "max-rpm", &maxrpm);
>> +	if (err) {
>> +		dev_err(dev, "missing max-rpm property of %pOFn\n", child);
>> +		return err;
>> +	}
>> +
>> +	err = rpm_range_to_index(dev, &data->rpm_range[i], maxrpm);
>> +	if (err) {
>> +		dev_err(dev, "invalid max-rpm %d of %pOFn\n", maxrpm, child);
>> +		return err;
>> +	}
>> +	data->max_rpm[i] = maxrpm;
>> +
>> +	err = of_property_read_u32(child, "target-rpm", &val);
>> +	/* Use provided target RPM else default to maxrpm */
>> +	if (!err)
>> +		data->target_rpm[i] = val;
>> +	else
>> +		data->target_rpm[i] = maxrpm;
>> +
>> +	/* Get pwms property for PWM control */
>> +	data->pwmd[i] = devm_fwnode_pwm_get(dev, &child->fwnode, NULL);
>> +
>> +	if (!IS_ERR(data->pwmd[i]))
>> +		return 0;
>> +
>> +	if (PTR_ERR(data->pwmd[i]) == -EPROBE_DEFER)
>> +		return PTR_ERR(data->pwmd[i]);
>> +
>> +	dev_dbg(dev, "Using chip default PWM");
>> +	data->pwmd[i] = pwm_request_from_chip(&data->chip, i, NULL);
>> +	if (!IS_ERR(data->pwmd[i]))
>> +		return 0;
> 
> Are these PWMs usuable at all for a consumer other than the driver
> itself? If not I'd doubt the added value of this patch.
That depends on DT. For testing purpose, I specified different pwm 
handle & those pwm unreference in DT where available for use via  sysfs 
export otherwise the resource was busy.
> 
>> +	dev_dbg(dev, "Failed to configure pwm for fan %d", i);
>> +	return PTR_ERR_OR_ZERO(data->pwmd[i]);
>> +}
>> +
>> +static int max6639_probe_from_dt(struct i2c_client *client,
>> +				 struct max6639_data *data)
>> +{
>> +	struct device *dev = &client->dev;
>> +	const struct device_node *np = dev->of_node;
>> +	struct device_node *child;
>> +	int err;
>> +
>> +	/* Compatible with non-DT platforms */
>> +	if (!np)
>> +		return 0;
>> +
>> +	for_each_child_of_node(np, child) {
>> +		if (strcmp(child->name, "fan"))
>> +			continue;
>> +
>> +		err = max6639_probe_child_from_dt(client, child, data);
>> +		if (err) {
>> +			of_node_put(child);
>> +			return err;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static struct max6639_data *to_max6639_pwm(struct pwm_chip *chip)
>> +{
>> +	return container_of(chip, struct max6639_data, chip);
>> +}
>> +
>> +static void max6639_pwm_get_state(struct pwm_chip *chip,
>> +				  struct pwm_device *pwm,
>> +				  struct pwm_state *state)
>> +{
>> +
>> +	struct max6639_data *data = to_max6639_pwm(chip);
>> +	struct i2c_client *client = data->client;
>> +	int value, i = pwm->hwpwm, x;
> 
> Please use pwm->hwpwm directly instead of i, this makes the code IMHO a
> bit more readable.
I used variable 'i' to make it look short. Can switch to pwm->hwpwm
> 
>> +	unsigned int freq;
>> +
>> +	mutex_lock(&data->update_lock);
>> +
>> +	value = i2c_smbus_read_byte_data(client, MAX6639_REG_FAN_CONFIG1(i));
>> +	if (value < 0)
>> +		goto abort;
>> +
>> +	if (value & MAX6639_FAN_CONFIG1_PWM) {
>> +		state->enabled = true;
>> +
>> +		/* Determine frequency from respective registers */
>> +		value = i2c_smbus_read_byte_data(client,
>> +						 MAX6639_REG_FAN_CONFIG3(i));
>> +		if (value < 0)
>> +			goto abort;
>> +		x = value & MAX6639_FAN_CONFIG3_FREQ_MASK;
>> +
>> +		value = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
>> +		if (value < 0)
>> +			goto abort;
>> +		if (value & MAX6639_GCONFIG_PWM_FREQ_HI)
>> +			x |= 0x4;
>> +		x &= 0x7;
>> +		freq = freq_table[x];
>> +
>> +		state->period = DIV_ROUND_UP_ULL(NSEC_PER_SEC, freq);
> 
> both NSEC_PER_SEC and freq fit into an unsigned int, so you can use the
> (cheaper) DIV_ROUND_UP here.
Sure. will update in next version
> 
>> +
>> +		value = i2c_smbus_read_byte_data(client,
>> +						 MAX6639_REG_TARGTDUTY(i));
>> +		if (value < 0)
>> +			goto abort;
>> +		/* max6639 supports 120 slots only */
>> +		state->duty_cycle = DIV_ROUND_UP_ULL(value * state->period,
>> +						     120);
> 
> s/120/MAX6639_REG_TARGTDUTY_SLOT/ ?
> 
> value * state->period might overflow. Use something like
> mul_u64_u32_div. (Hmm, there doesn't seem to be a variant for unsigned *
> unsigned / unsigned?)
Yeah that seems better. Will update in next version
> 
> You're loosing precision here. Consider freq = 8333 and TARGTDUTY = 97
> then you have state->period = 120005 and calulate duty_cycle as:
> 
> 	DIV_ROUND_UP_ULL(97 * 120005, 120) = 97005
> 
> . The exact value is (I guess)
> 
> 	97 * NSEC_PER_SEC / (8333 * 120) = 97003.880
> 
For this chip, it may not matter as it supports only 120 slots.

>> +		value = i2c_smbus_read_byte_data(client,
>> +						 MAX6639_REG_FAN_CONFIG2a(i));
>> +		if (value < 0)
>> +			goto abort;
>> +		value &= MAX6639_REG_FAN_CONFIG2a_PWM_POL;
>> +		state->polarity = (value != 0);
>> +	} else
>> +		state->enabled = false;
>> +
>> +abort:
>> +	mutex_unlock(&data->update_lock);
>> +
>> +}
>> +
>> +static int max6639_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>> +			     const struct pwm_state *state)
>> +{
>> +	struct max6639_data *data = to_max6639_pwm(chip);
>> +	struct i2c_client *client = data->client;
>> +	int value = 0, i = pwm->hwpwm, x;
> 
> Please use pwm->hwpwm directly instead of i, this makes the code IMHO a
> bit more readable.
I used variable 'i' to make it look short. Can switch to pwm->hwpwm
> 
>> +	unsigned int freq;
>> +	struct pwm_state cstate;
>> +
>> +	pwm_get_state(pwm, &cstate);
> 
> Please don't use pwm API functions in PWM callbacks. Accessing
> pwm->state is fine here.
Sure.
> 
>> +	mutex_lock(&data->update_lock);
>> +
>> +	if (state->period != cstate.period) {
>> +		/* Configure frequency */
>> +		freq = DIV_ROUND_UP_ULL(NSEC_PER_SEC, state->period);
>> +		/* Chip supports limited number of frequency */
>> +		for (x = 0; x < sizeof(freq_table); x++)
>> +			if (freq < freq_table[x])
>> +				break;
> 
> For state->period = 80000 we get:
> 
> 	freq = 12500
> 
> and then x = 7 is picked while x = 6 would be an exact match.
> 
> I think you just need
> 
> 	if (freq <= freq_table[x])
> 
Yes. Will update in next revision.
>> +		value = i2c_smbus_read_byte_data(client,
>> +						 MAX6639_REG_FAN_CONFIG3(i));
>> +		if (value < 0)
>> +			goto abort;
>> +		value &= ~MAX6639_FAN_CONFIG3_FREQ_MASK;
>> +		value |= (x & MAX6639_FAN_CONFIG3_FREQ_MASK);
>> +		value = i2c_smbus_write_byte_data(client,
>> +						  MAX6639_REG_FAN_CONFIG3(i),
>> +						  value);
>> +
>> +		value = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
>> +		if (value < 0)
>> +			goto abort;
>> +
>> +		if ((value & MAX6639_GCONFIG_PWM_FREQ_HI) && (x >> 2))
>> +			value &= ~MAX6639_GCONFIG_PWM_FREQ_HI;
>> +		else
>> +			value |= MAX6639_GCONFIG_PWM_FREQ_HI;
>> +		value = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
>> +						  value);
> 
> Why does it depend on MAX6639_GCONFIG_PWM_FREQ_HI being already set if
> you need to set it?
> 
Yes. Will update in next version
>> +		if (value < 0)
>> +			goto abort;
>> +	}
>> +
>> +	/* Configure dutycycle */
>> +	if (state->duty_cycle != cstate.duty_cycle) {
> 
> That check is wrong if you go from
> 
> 	.duty_cycle = 50000; .period = 200000
> 
> to
> 
> 	.duty_cycle = 50000; .period = 100000
> 
> 
Yes. Will update in next revision.
>> +		value = DIV_ROUND_UP_ULL(
>> +				state->duty_cycle * MAX6639_REG_TARGTDUTY_SLOT,
>> +				state->period);
> 
> Please round down here. (And test with PWM_DEBUG which might have told
> you given the right tests.) Also please use the real period to determine
> the register value. (Otherwise for a request with
> 
> 	.duty_cycle = 40000; .period = 150000
> 
> where a real period of 120004.8 ns is picked you get
> MAX6639_REG_TARGTDUTY_SLOT = 32 which results in a duty cycle of
> 32001.28 ns, while with MAX6639_REG_TARGTDUTY_SLOT = 39 you'd get
> 39001.56 ns.
> 
Sure will update to round down.
>> +		value = i2c_smbus_write_byte_data(client,
>> +						  MAX6639_REG_TARGTDUTY(i),
>> +						  value);
>> +		if (value < 0)
>> +			goto abort;
>> +	}
>> +
>> +	/* Configure polarity */
>> +	if (state->polarity != cstate.polarity) {
>> +		value = i2c_smbus_read_byte_data(client,
>> +						 MAX6639_REG_FAN_CONFIG2a(i));
>> +		if (value < 0)
>> +			goto abort;
>> +		if (state->polarity == PWM_POLARITY_NORMAL)
>> +			value |= MAX6639_REG_FAN_CONFIG2a_PWM_POL;
>> +		else
>> +			value &= ~MAX6639_REG_FAN_CONFIG2a_PWM_POL;
>> +		value = i2c_smbus_write_byte_data(client,
>> +						  MAX6639_REG_FAN_CONFIG2a(i),
>> +						  value);
>> +		if (value < 0)
>> +			goto abort;
>> +	}
>> +
>> +	if (state->enabled == cstate.enabled)
>> +		goto abort;
> 
> Please use goto only for error handling.
> >> +
>> +	value = i2c_smbus_read_byte_data(client, MAX6639_REG_FAN_CONFIG1(i));
>> +	if (value < 0)
>> +		goto abort;
>> +	if (state->enabled)
>> +		value |= MAX6639_FAN_CONFIG1_PWM;
>> +	else
>> +		value &= ~MAX6639_FAN_CONFIG1_PWM;
>> +
>> +	value = i2c_smbus_write_byte_data(client, MAX6639_REG_FAN_CONFIG1(i),
>> +					  value);
>> +	if (value < 0)
>> +		goto abort;
>> +	value = 0;
>> +
>> +abort:
>> +	mutex_unlock(&data->update_lock);
>> +
>> +	return value;
>> +}
>> +
>> +static const struct pwm_ops max6639_pwm_ops = {
>> +	.apply = max6639_pwm_apply,
>> +	.get_state = max6639_pwm_get_state,
>> +	.owner = THIS_MODULE,
>> +};
>> +
>>   static int max6639_probe(struct i2c_client *client)
>>   {
>>   	struct device *dev = &client->dev;
>>   	struct max6639_data *data;
>>   	struct device *hwmon_dev;
>> -	int err;
>> +	int err, i;
>>   
>>   	data = devm_kzalloc(dev, sizeof(struct max6639_data), GFP_KERNEL);
>>   	if (!data)
>> @@ -537,11 +812,26 @@ static int max6639_probe(struct i2c_client *client)
>>   
>>   	data->client = client;
>>   
>> +	/* Add PWM controller of max6639 */
>> +	data->chip.dev = dev;
>> +	data->chip.ops = &max6639_pwm_ops;
>> +	data->chip.npwm = 2;
>> +	data->chip.of_pwm_n_cells = 3;
> 
> Please drop this, of_pwmchip_add() overwrites it anyhow.
> 
Sure.
>> +
>> +	err = devm_pwmchip_add(dev, &data->chip);
>> +	if (err < 0) {
>> +		dev_err(dev, "failed to add PWM chip %d\n", err);
> 
> dev_err_probe please.
> 
Sure.
>> +		return err;
>> +	}
>> +
>>   	data->reg = devm_regulator_get_optional(dev, "fan");
>>   	if (IS_ERR(data->reg)) {
>> -		if (PTR_ERR(data->reg) != -ENODEV)
>> -			return PTR_ERR(data->reg);
>> -
>> +		if (PTR_ERR(data->reg) != -ENODEV) {
>> +			err = (int)PTR_ERR(data->reg);
>> +			dev_warn(dev, "Failed looking up fan supply: %d\n",
>> +				 err);
> 
> unrelated change. Also dev_probe_err is better suited here.
> 
Sure.
>> +			return err;
>> +		}
>>   		data->reg = NULL;
>>   	} else {
>>   		/* Spin up fans */
>> @@ -560,6 +850,22 @@ static int max6639_probe(struct i2c_client *client)
>>   
>>   	mutex_init(&data->update_lock);
>>   
>> +	/* Below are defaults leter overridden by DT properties */
>> +	for (i = 0; i < 2; i++) {
>> +		/* 4000 RPM */
>> +		data->rpm_range[i] = 1;
>> +		data->ppr[i] = 2;
>> +		/* Max. temp. 80C/90C/100C */
>> +		data->temp_therm[i] = 80;
>> +		data->temp_alert[i] = 90;
>> +		data->temp_ot[i] = 100;
>> +	}
>> +
>> +	/* Probe from DT to get configuration */
>> +	err = max6639_probe_from_dt(client, data);
>> +	if (err)
>> +		return err;
>> +
>>   	/* Initialize the max6639 chip */
>>   	err = max6639_init_client(client, data);
>>   	if (err < 0)
>> @@ -571,6 +877,7 @@ static int max6639_probe(struct i2c_client *client)
>>   	return PTR_ERR_OR_ZERO(hwmon_dev);
>>   }
>>   
>> +#if IS_ENABLED(CONFIG_PM_SLEEP)
> 
> unrelated change
> 
Have put this to avoid error when CONFIG_PM_SLEEP is disabled.
>>   static int max6639_suspend(struct device *dev)
>>   {
>>   	struct i2c_client *client = to_i2c_client(dev);
>> @@ -608,6 +915,7 @@ static int max6639_resume(struct device *dev)
>>   	return i2c_smbus_write_byte_data(client,
>>   			MAX6639_REG_GCONFIG, ret & ~MAX6639_GCONFIG_STANDBY);
>>   }
>> +#endif
>>   
>>   static const struct i2c_device_id max6639_id[] = {
>>   	{"max6639", 0},
>> @@ -616,13 +924,22 @@ static const struct i2c_device_id max6639_id[] = {
>>   
>>   MODULE_DEVICE_TABLE(i2c, max6639_id);
>>   
>> -static DEFINE_SIMPLE_DEV_PM_OPS(max6639_pm_ops, max6639_suspend, max6639_resume);
>> +#ifdef CONFIG_OF
> 
> Note that ACPI also uses of_match_table.
> 
>> +static const struct of_device_id maxim_of_platform_match[] = {
>> +	{.compatible = "maxim,max6639"},
>> +	{},
>> +};
>> +MODULE_DEVICE_TABLE(of, maxim_of_platform_match);
>> +#endif
>> +
>> +static SIMPLE_DEV_PM_OPS(max6639_pm_ops, max6639_suspend, max6639_resume);
>>   
>>   static struct i2c_driver max6639_driver = {
>>   	.class = I2C_CLASS_HWMON,
>>   	.driver = {
>>   		   .name = "max6639",
>>   		   .pm = pm_sleep_ptr(&max6639_pm_ops),
>> +		   .of_match_table = of_match_ptr(maxim_of_platform_match),
>>   		   },
>>   	.probe_new = max6639_probe,
>>   	.id_table = max6639_id,
> 
> Best regards
> Uwe
> 
Regards,
Naresh

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