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Date: Wed, 12 Jun 2024 08:55:45 -0700
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Subject: Re: [PATCH v4 2/2] hwmon: (max6639) : Add hwmon attributes for fan
 and pwm
To: Naresh Solanki <naresh.solanki@9elements.com>,
 Jean Delvare <jdelvare@suse.com>
Cc: linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20240604124742.4093334-1-naresh.solanki@9elements.com>
 <20240604124742.4093334-2-naresh.solanki@9elements.com>
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From: Guenter Roeck <linux@roeck-us.net>
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In-Reply-To: <20240604124742.4093334-2-naresh.solanki@9elements.com>
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On 6/4/24 05:47, Naresh Solanki wrote:
> Add attribute for fan & pwm i.e.,
> fanY_pulse
> pwmY_freq
> 
> Signed-off-by: Naresh Solanki <naresh.solanki@9elements.com>
> ---
>   drivers/hwmon/max6639.c | 74 ++++++++++++++++++++++++++++++++++++++---
>   1 file changed, 70 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hwmon/max6639.c b/drivers/hwmon/max6639.c
> index e2a5210f9f95..6c7eaeeb2a80 100644
> --- a/drivers/hwmon/max6639.c
> +++ b/drivers/hwmon/max6639.c
> @@ -235,6 +235,9 @@ static int max6639_read_fan(struct device *dev, u32 attr, int channel,
>   			return res;
>   		*fan_val = !!(val & BIT(1 - channel));
>   		return 0;
> +	case hwmon_fan_pulses:
> +		*fan_val = data->ppr[channel];
> +		return 0;
>   	default:
>   		return -EOPNOTSUPP;
>   	}
> @@ -246,6 +249,32 @@ static int max6639_set_ppr(struct max6639_data *data, int channel, u8 ppr)
>   	return regmap_write(data->regmap, MAX6639_REG_FAN_PPR(channel), ppr-- << 6);
>   }
>   
> +static int max6639_write_fan(struct device *dev, u32 attr, int channel,
> +			     long val)
> +{
> +	struct max6639_data *data = dev_get_drvdata(dev);
> +	int err;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +

Unnecessary check.

> +	switch (attr) {
> +	case hwmon_fan_pulses:
> +		if (val <= 0 || val > 5)
> +			return -EINVAL;
> +
> +		/* Set Fan pulse per revolution */
> +		err = max6639_set_ppr(data, channel, val);
> +		if (err < 0)
> +			return err;
> +
> +		data->ppr[channel] = val;

Needs mutex protection to avoid inconsistencies due to concurrent writes.

> +		return 0;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
>   static umode_t max6639_fan_is_visible(const void *_data, u32 attr, int channel)
>   {
>   	struct max6639_data *data = (struct max6639_data *)_data;
> @@ -270,6 +299,7 @@ static int max6639_read_pwm(struct device *dev, u32 attr, int channel,
>   	struct max6639_data *data = dev_get_drvdata(dev);
>   	unsigned int val;
>   	int res;
> +	u8 i;
>   
>   	if (IS_ERR(data))
>   		return PTR_ERR(data);
> @@ -281,6 +311,21 @@ static int max6639_read_pwm(struct device *dev, u32 attr, int channel,
>   			return res;
>   		*pwm_val = val * 255 / 120;
>   		return 0;
> +	case hwmon_pwm_freq:
> +		res = regmap_read(data->regmap, MAX6639_REG_FAN_CONFIG3(channel), &val);
> +		if (res < 0)
> +			return res;
> +		i = val & MAX6639_FAN_CONFIG3_FREQ_MASK;
> +
> +		res = regmap_read(data->regmap, MAX6639_REG_GCONFIG, &val);
> +		if (res < 0)
> +			return res;
> +
> +		if (val & MAX6639_GCONFIG_PWM_FREQ_HI)
> +			i |= 0x4;

This sequence will need to be mutex protected to avoid consistency errors if
a write happens at the same time.


> +		i &= 0x7;
> +		*pwm_val = freq_table[i];
> +		return 0;
>   	default:
>   		return -EOPNOTSUPP;
>   	}
> @@ -291,6 +336,7 @@ static int max6639_write_pwm(struct device *dev, u32 attr, int channel,
>   {
>   	struct max6639_data *data = dev_get_drvdata(dev);
>   	int err;
> +	u8 i;
>   
>   	if (IS_ERR(data))
>   		return PTR_ERR(data);
> @@ -301,6 +347,23 @@ static int max6639_write_pwm(struct device *dev, u32 attr, int channel,
>   		err = regmap_write(data->regmap, MAX6639_REG_TARGTDUTY(channel),
>   				   val * 120 / 255);
>   		return err;
> +	case hwmon_pwm_freq:
> +		val = clamp_val(val, 0, 25000);
> +
> +		i = find_closest(val, freq_table, ARRAY_SIZE(freq_table));
> +
> +		err = regmap_update_bits(data->regmap, MAX6639_REG_FAN_CONFIG3(channel),
> +					 MAX6639_FAN_CONFIG3_FREQ_MASK, i);
> +		if (err < 0)
> +			return err;
> +
> +		if (i >> 2)
> +			err = regmap_set_bits(data->regmap, MAX6639_REG_GCONFIG,
> +					      MAX6639_GCONFIG_PWM_FREQ_HI);
> +		else
> +			err = regmap_clear_bits(data->regmap, MAX6639_REG_GCONFIG,
> +						MAX6639_GCONFIG_PWM_FREQ_HI);

Same as above. In general, every operation with more than a single element
needs to be mutex protected.

> +		return err;
>   	default:
>   		return -EOPNOTSUPP;
>   	}
> @@ -310,6 +373,7 @@ static umode_t max6639_pwm_is_visible(const void *_data, u32 attr, int channel)
>   {
>   	switch (attr) {
>   	case hwmon_pwm_input:
> +	case hwmon_pwm_freq:
>   		return 0644;
>   	default:
>   		return 0;
> @@ -415,6 +479,8 @@ static int max6639_write(struct device *dev, enum hwmon_sensor_types type,
>   			 u32 attr, int channel, long val)
>   {
>   	switch (type) {
> +	case hwmon_fan:
> +		return max6639_write_fan(dev, attr, channel, val);
>   	case hwmon_pwm:
>   		return max6639_write_pwm(dev, attr, channel, val);
>   	case hwmon_temp:
> @@ -442,11 +508,11 @@ static umode_t max6639_is_visible(const void *data,
>   
>   static const struct hwmon_channel_info * const max6639_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_PULSES,
> +			   HWMON_F_INPUT | HWMON_F_FAULT | HWMON_F_PULSES),
>   	HWMON_CHANNEL_INFO(pwm,
> -			   HWMON_PWM_INPUT,
> -			   HWMON_PWM_INPUT),
> +			   HWMON_PWM_INPUT | HWMON_PWM_FREQ,
> +			   HWMON_PWM_INPUT | HWMON_PWM_FREQ),
>   	HWMON_CHANNEL_INFO(temp,
>   			   HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_MAX | HWMON_T_MAX_ALARM |
>   			   HWMON_T_CRIT | HWMON_T_CRIT_ALARM | HWMON_T_EMERGENCY |