Message-ID: <20221125161854.GA1171306@roeck-us.net>
Date:   Fri, 25 Nov 2022 08:18:54 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Naresh Solanki <naresh.solanki@...ements.com>
Cc:     devicetree@...r.kernel.org, Jean Delvare <jdelvare@...e.com>,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>,
        Marcello Sylvester Bauer <sylv@...v.io>
Subject: Re: [PATCH v7 3/4] hwmon: (max6639) Change from pdata to dt
 configuration

On Mon, Nov 21, 2022 at 01:29:31PM +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.
> 

This patch does way more than that.

> Signed-off-by: Marcello Sylvester Bauer <sylv@...v.io>
> Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
> ---
>  drivers/hwmon/max6639.c               | 246 +++++++++++++++++++-------
>  include/linux/platform_data/max6639.h |  15 --
>  2 files changed, 178 insertions(+), 83 deletions(-)
>  delete mode 100644 include/linux/platform_data/max6639.h
> 
> diff --git a/drivers/hwmon/max6639.c b/drivers/hwmon/max6639.c
> index 9b895402c80d..feafa3511297 100644
> --- a/drivers/hwmon/max6639.c
> +++ b/drivers/hwmon/max6639.c
> @@ -19,7 +19,6 @@
>  #include <linux/hwmon-sysfs.h>
>  #include <linux/err.h>
>  #include <linux/mutex.h>
> -#include <linux/platform_data/max6639.h>
>  
>  /* Addresses to scan */
>  static const unsigned short normal_i2c[] = { 0x2c, 0x2e, 0x2f, I2C_CLIENT_END };
> @@ -54,9 +53,12 @@ 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 };
>  
>  #define FAN_FROM_REG(val, rpm_range)	((val) == 0 || (val) == 255 ? \
> @@ -76,18 +78,21 @@ 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 */
> +	u32 target_rpm[2];
> +	u32 max_rpm[2];
> +	u8 pwm[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 */
> +	u8 pwm_polarity[2];
>  	/* Optional regulator for FAN supply */
>  	struct regulator *reg;
>  };
> @@ -282,6 +287,7 @@ static ssize_t pwm_show(struct device *dev, struct device_attribute *dev_attr,
>  	struct max6639_data *data = dev_get_drvdata(dev);
>  
>  	return sprintf(buf, "%d\n", data->pwm[attr->index] * 255 / 120);
> +

Unnecessary and wrong whitespace change.

>  }
>  
>  static ssize_t pwm_store(struct device *dev,
> @@ -302,10 +308,10 @@ static ssize_t pwm_store(struct device *dev,
>  
>  	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]);
> +	i2c_smbus_write_byte_data(client, MAX6639_REG_TARGTDUTY(attr->index),
> +				 data->pwm[attr->index]);
>  	mutex_unlock(&data->update_lock);
> +
>  	return count;

Unnecessary formatting change. You may not like the original formatting,
but that is no reason to change it.

>  }
>  
> @@ -319,7 +325,7 @@ 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 +392,40 @@ 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;

The above changes are unrelated to $subject. Also, the same could be
accomplished by varying the range check in the for loop, making the
change POV. The warning is both unacceptable and unnecessary.

>  }
>  
>  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;
>  
>  	/* Reset chip to default values, see below for GCONFIG setup */
>  	err = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
> @@ -416,51 +433,29 @@ 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]);

The above change silently drops the configuration of
MAX6639_REG_FAN_CONFIG2a, which is puzzling since the patch
also introduces MAX6639_REG_FAN_CONFIG2a_PWM_POL which isn't
used. I don't see what this has to do with $subject, and the
lack of explanation is not really reassuring.

>  		if (err)
>  			goto exit;
>  
>  		/*
> -		 * /THERM full speed enable,
> +		 * /THERM full speed disable,

Change unrelated to $subject and possibly unexpected results
for users of this driver.

>  		 * 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 +464,34 @@ 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]);

Unrelated formatting changes above. Such changes just obfuscate functional
changes made in the patch and are unacceptable. If you want to fix
checkpatch issues, do it in a separate patch.

I am stopping the review here. In the future, please refrain from making
unrelated changes. One logical change per patch, please.

Guenter

>  		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]);
> +		data->pwm[i] = data->target_rpm[i];
> +		err = i2c_smbus_write_byte_data(client, MAX6639_REG_TARGTDUTY(i), data->pwm[i]);
> +
>  		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 +522,95 @@ 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;
> +
> +	return 0;
> +}
> +
> +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 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)
> @@ -539,9 +620,11 @@ static int max6639_probe(struct i2c_client *client)
>  
>  	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);
> +			return dev_err_probe(dev, err,
> +					     "Failed looking up fan supply\n");
> +		}
>  		data->reg = NULL;
>  	} else {
>  		/* Spin up fans */
> @@ -560,6 +643,22 @@ static int max6639_probe(struct i2c_client *client)
>  
>  	mutex_init(&data->update_lock);
>  
> +	/* Below are defaults later 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 +670,7 @@ static int max6639_probe(struct i2c_client *client)
>  	return PTR_ERR_OR_ZERO(hwmon_dev);
>  }
>  
> +#if IS_ENABLED(CONFIG_PM_SLEEP)
>  static int max6639_suspend(struct device *dev)
>  {
>  	struct i2c_client *client = to_i2c_client(dev);
> @@ -608,6 +708,7 @@ 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 +717,22 @@ 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
> +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,
> diff --git a/include/linux/platform_data/max6639.h b/include/linux/platform_data/max6639.h
> deleted file mode 100644
> index 65bfdb4fdc15..000000000000
> --- a/include/linux/platform_data/max6639.h
> +++ /dev/null
> @@ -1,15 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0 */
> -#ifndef _LINUX_MAX6639_H
> -#define _LINUX_MAX6639_H
> -
> -#include <linux/types.h>
> -
> -/* platform data for the MAX6639 temperature sensor and fan control */
> -
> -struct max6639_platform_data {
> -	bool pwm_polarity;	/* Polarity low (0) or high (1, default) */
> -	int ppr;		/* Pulses per rotation 1..4 (default == 2) */
> -	int rpm_range;		/* 2000, 4000 (default), 8000 or 16000 */
> -};
> -
> -#endif /* _LINUX_MAX6639_H */

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