Message-ID: <d5846bef-4d0b-9527-c6e5-c71a8a5ba29f@roeck-us.net>
Date:   Tue, 11 Oct 2022 09:57:26 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Naresh Solanki <naresh.solanki@...ements.com>,
        devicetree@...r.kernel.org, Jean Delvare <jdelvare@...e.com>
Cc:     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 v2 3/3] hwmon: (max6639) Change from pdata to dt
 configuration

On 10/11/22 03:47, Naresh Solanki wrote:
> From: Marcello Sylvester Bauer <sylv@...v.io>
> 
> max6639_platform_data is not used by any in-kernel driver and does not
> address the MAX6639 channels separately. Move to device tree
> configuration with explicit properties to configure each channel.
> 

This patch does way more than that. It introduces several additional
configuration options. The patch will have to be split into several patches,
each with a single logical change.

> 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/max6639.c               | 260 +++++++++++++++++++-------
>   include/linux/platform_data/max6639.h |  15 --
>   2 files changed, 197 insertions(+), 78 deletions(-)
>   delete mode 100644 include/linux/platform_data/max6639.h
> 
> diff --git a/drivers/hwmon/max6639.c b/drivers/hwmon/max6639.c
> index 9b895402c80d..75eb4522fc9b 100644
> --- a/drivers/hwmon/max6639.c
> +++ b/drivers/hwmon/max6639.c
> @@ -19,48 +19,53 @@
>   #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 };
>   
>   /* The MAX6639 registers, valid channel numbers: 0, 1 */
>   #define MAX6639_REG_TEMP(ch)			(0x00 + (ch))
> -#define MAX6639_REG_STATUS			0x02
> +#define MAX6639_REG_STATUS				0x02
>   #define MAX6639_REG_OUTPUT_MASK			0x03
> -#define MAX6639_REG_GCONFIG			0x04
> +#define MAX6639_REG_GCONFIG				0x04
>   #define MAX6639_REG_TEMP_EXT(ch)		(0x05 + (ch))
>   #define MAX6639_REG_ALERT_LIMIT(ch)		(0x08 + (ch))
>   #define MAX6639_REG_OT_LIMIT(ch)		(0x0A + (ch))
>   #define MAX6639_REG_THERM_LIMIT(ch)		(0x0C + (ch))
>   #define MAX6639_REG_FAN_CONFIG1(ch)		(0x10 + (ch) * 4)
> -#define MAX6639_REG_FAN_CONFIG2a(ch)		(0x11 + (ch) * 4)
> -#define MAX6639_REG_FAN_CONFIG2b(ch)		(0x12 + (ch) * 4)
> +#define MAX6639_REG_FAN_CONFIG2a(ch)	(0x11 + (ch) * 4)
> +#define MAX6639_REG_FAN_CONFIG2b(ch)	(0x12 + (ch) * 4)
>   #define MAX6639_REG_FAN_CONFIG3(ch)		(0x13 + (ch) * 4)
>   #define MAX6639_REG_FAN_CNT(ch)			(0x20 + (ch))
>   #define MAX6639_REG_TARGET_CNT(ch)		(0x22 + (ch))
>   #define MAX6639_REG_FAN_PPR(ch)			(0x24 + (ch))
>   #define MAX6639_REG_TARGTDUTY(ch)		(0x26 + (ch))
> -#define MAX6639_REG_FAN_START_TEMP(ch)		(0x28 + (ch))
> -#define MAX6639_REG_DEVID			0x3D
> -#define MAX6639_REG_MANUID			0x3E
> -#define MAX6639_REG_DEVREV			0x3F
> +#define MAX6639_REG_FAN_START_TEMP(ch)	(0x28 + (ch))
> +#define MAX6639_REG_DEVID				0x3D
> +#define MAX6639_REG_MANUID				0x3E
> +#define MAX6639_REG_DEVREV				0x3F
>   
>   /* Register bits */
> +#define MAX6639_REG_OUTPUT_MASK_OT(x, ch)		(x << (5 - ch))
> +#define MAX6639_REG_OUTPUT_MASK_THERM(x, ch)	(x << (3 - ch))
> +#define MAX6639_REG_OUTPUT_MASK_FANFAIL(x, ch)	(x << (1 - ch))
>   #define MAX6639_GCONFIG_STANDBY			0x80
> -#define MAX6639_GCONFIG_POR			0x40
> -#define MAX6639_GCONFIG_DISABLE_TIMEOUT		0x20
> +#define MAX6639_GCONFIG_POR				0x40
> +#define MAX6639_GCONFIG_DISABLE_TIMEOUT	0x20
>   #define MAX6639_GCONFIG_CH2_LOCAL		0x10
>   #define MAX6639_GCONFIG_PWM_FREQ_HI		0x08
>   
>   #define MAX6639_FAN_CONFIG1_PWM			0x80
>   
> +#define MAX6639_FAN_CONFIG3_THERM_FULL_SPEED	0x40
> +#define MAX6639_FAN_CONFIG3_SPIN_UP_DISABLE		0x80
>   #define MAX6639_FAN_CONFIG3_THERM_FULL_SPEED	0x40
>   
>   static const int rpm_ranges[] = { 2000, 4000, 8000, 16000 };
>   
>   #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)
>   
>   /*
> @@ -69,7 +74,7 @@ static const int rpm_ranges[] = { 2000, 4000, 8000, 16000 };
>   struct max6639_data {
>   	struct i2c_client *client;
>   	struct mutex update_lock;
> -	bool valid;		/* true if following fields are valid */
> +	char valid;		/* !=0 if following fields are valid */
>   	unsigned long last_updated;	/* In jiffies */
>   
>   	/* Register values sampled regularly */
> @@ -85,9 +90,14 @@ struct max6639_data {
>   	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];	/* Fans PWM polarity, 0..1 */
> +	bool full_speed_on_therm[2];	/* disable THERM full speed assertion */
> +	bool spin_up_enable[2];		/* Enable fan spin-up if fan is not spinning */
> +	bool ot_indication[2];		/* Enable OT pin indication */
> +	bool therm_indication[2];	/* Enable THERM pin indication */
> +	bool fan_fail_indication[2];	/* Enable FANFAIL pin indication */
>   	/* Optional regulator for FAN supply */
>   	struct regulator *reg;
>   };
> @@ -144,7 +154,7 @@ static struct max6639_data *max6639_update_device(struct device *dev)
>   		}
>   
>   		data->last_updated = jiffies;
> -		data->valid = true;
> +		data->valid = 1;
>   	}
>   abort:
>   	mutex_unlock(&data->update_lock);
> @@ -319,7 +329,7 @@ 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,
> @@ -386,28 +396,34 @@ 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(u8 *index, int rpm)
>   {
>   	int i;
>   
> +	if (rpm <= 0)
> +		return -EINVAL;
> +
> +	/* If provided RPM is more than 16000 RPM then select 16000
> +	 * RPM range.
> +	 */
> +	*index = ARRAY_SIZE(rpm_ranges) - 1;
> +
>   	for (i = 0; i < ARRAY_SIZE(rpm_ranges); i++) {
> -		if (rpm_ranges[i] == range)
> -			return i;
> +		if (rpm <= rpm_ranges[i]) {
> +			*index = i;
> +			break;
> +		}
>   	}
>   
> -	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 i, val;
>   	int err;
>   
>   	/* Reset chip to default values, see below for GCONFIG setup */
> @@ -416,58 +432,40 @@ 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);
> +				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);
> +			MAX6639_FAN_CONFIG1_PWM | data->rpm_range[i]);
>   		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);
> -		if (err)
> -			goto exit;
> +		/* Fans PWM polarity */
> +		err = i2c_smbus_write_byte_data(client,
> +			MAX6639_REG_FAN_CONFIG2a(i), data->pwm_polarity[i] ? 0x02 : 0x00);
>   
>   		/*
> -		 * /THERM full speed enable,
> +		 * Full speed on therm, spin-up at zero rpm.
>   		 * 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);
> +			(data->full_speed_on_therm[i] ?
> +			 MAX6639_FAN_CONFIG3_THERM_FULL_SPEED : 0) |
> +			(data->spin_up_enable[i] ?
> +			 0 : MAX6639_FAN_CONFIG3_SPIN_UP_DISABLE) | 0x03);
> +
>   		if (err)
>   			goto exit;
>   
> -		/* Max. temp. 80C/90C/100C */
> -		data->temp_therm[i] = 80;
> -		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]);
> @@ -483,13 +481,24 @@ static int max6639_init_client(struct i2c_client *client,
>   		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]);
>   		if (err)
>   			goto exit;
>   	}
> +
> +	val = 0;
> +	for (i = 0; i < 2; i++) {
> +		val |= MAX6639_REG_OUTPUT_MASK_OT(
> +				data->ot_indication[i], i);
> +		val |= MAX6639_REG_OUTPUT_MASK_THERM(
> +				data->therm_indication[i], i);
> +		val |= MAX6639_REG_OUTPUT_MASK_FANFAIL(
> +				data->fan_fail_indication[i], i);
> +	}
> +	/* Configure output mask register */
> +	err = i2c_smbus_write_byte_data(client, MAX6639_REG_OUTPUT_MASK, val);
> +
>   	/* Start monitoring */
>   	err = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
>   		MAX6639_GCONFIG_DISABLE_TIMEOUT | MAX6639_GCONFIG_CH2_LOCAL |
> @@ -524,12 +533,105 @@ 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, val, maxrpm;
> +	int 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\n", 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(&data->rpm_range[i], maxrpm);
> +	if (err) {
> +		dev_err(dev, "invalid max-rpm %d of %pOFn\n", maxrpm, child);
> +		return err;
> +	}
> +
> +
> +	err = of_property_read_u32(child, "target-rpm", &val);
> +	/* Convert to PWM from provided target RPM */
> +	if (!err && val != 0)
> +		data->pwm[i] =
> +			(u8)(val * 255 / maxrpm);
> +
> +	data->pwm_polarity[i] =  of_property_read_bool(child, "pwm-polarity-inverse");
> +
> +	data->spin_up_enable[i] = of_property_read_bool(child, "maxim,fan-spin-up");
> +
> +	data->full_speed_on_therm[i] = of_property_read_bool(child,
> +		"maxim,full-speed-on-therm");
> +
> +	data->fan_fail_indication[i] = of_property_read_bool(child, "maxim,fanfail_indication");
> +
> +	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;
> +		}
> +	}
> +
> +	data->ot_indication[0] = !of_property_read_bool(np, "ot0_indication");
> +	data->ot_indication[1] = !of_property_read_bool(np, "ot1_indication");
> +	data->therm_indication[0] = !of_property_read_bool(np, "therm0_indication");
> +	data->therm_indication[1] = !of_property_read_bool(np, "therm1_indication");
> +
> +	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 +641,11 @@ 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);
> +			dev_warn(dev, "Failed looking up fan supply: %d\n", err);
> +			return err;
> +		}
>   		data->reg = NULL;
>   	} else {
>   		/* Spin up fans */
> @@ -560,6 +664,25 @@ static int max6639_probe(struct i2c_client *client)
>   
>   	mutex_init(&data->update_lock);
>   
> +	/* default values */
> +	for (i = 0; i < 2; i++) {
> +		/* 4000 RPM */
> +		data->rpm_range[i] = 1;
> +		data->ppr[i] = 2;
> +		data->pwm_polarity[i] = 1;
> +		/* Max. temp. 80C/90C/100C */
> +		data->temp_therm[i] = 80;
> +		data->temp_alert[i] = 90;
> +		data->temp_ot[i] = 100;
> +		/* PWM 120/120 (i.e. 100%) */
> +		data->pwm[i] = 120;
> +		data->full_speed_on_therm[i] = false;
> +	}

This is an absolute no-go. Do not make up random default values.
Default is whatever is configured into the chip (it may have been
configured by the ROMMON / BIOS).

Guenter

> +
> +	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 +694,7 @@ 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 +732,7 @@ 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 +741,22 @@ 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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