linux-kernel - Re: [PATCH] hwmon: (max31790) add fanN

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Message-ID: <20220829132017.GA3039965@roeck-us.net>
Date:   Mon, 29 Aug 2022 06:20:17 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Justin Ledford <justinledford@...gle.com>
Cc:     Jean Delvare <jdelvare@...e.com>, Jonathan Corbet <corbet@....net>,
        linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (max31790) add fanN_enable

On Mon, Aug 29, 2022 at 02:43:51AM +0000, Justin Ledford wrote:
> The MAX31790 has a tach input enable bit in each fan's configuration
> register. This is only enabled by the driver if RPM mode is selected,
> but the driver doesn't provide a way to independently enable tachometer
> input regardless of the regulator mode.
> 
> By adding the fanN_enable sysfs files, we can decouple the tach input
> from the regulator mode. Also update the documentation.
> 
> Signed-off-by: Justin Ledford <justinledford@...gle.com>
> ---
>  Documentation/hwmon/max31790.rst |  1 +
>  drivers/hwmon/max31790.c         | 44 +++++++++++++++++++++++++++-----
>  2 files changed, 38 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/hwmon/max31790.rst b/Documentation/hwmon/max31790.rst
> index 7b097c3b9b90..33c5c7330efc 100644
> --- a/Documentation/hwmon/max31790.rst
> +++ b/Documentation/hwmon/max31790.rst
> @@ -38,6 +38,7 @@ Sysfs entries
>  fan[1-12]_input    RO  fan tachometer speed in RPM
>  fan[1-12]_fault    RO  fan experienced fault
>  fan[1-6]_target    RW  desired fan speed in RPM
> +fan[1-6]_enable    RW  enable or disable the tachometer input
>  pwm[1-6]_enable    RW  regulator mode, 0=disabled (duty cycle=0%), 1=manual mode, 2=rpm mode
>  pwm[1-6]           RW  read: current pwm duty cycle,
>                         write: target pwm duty cycle (0-255)
> diff --git a/drivers/hwmon/max31790.c b/drivers/hwmon/max31790.c
> index 7e9362f6dc29..3ae02be4b41e 100644
> --- a/drivers/hwmon/max31790.c
> +++ b/drivers/hwmon/max31790.c
> @@ -118,6 +118,12 @@ static struct max31790_data *max31790_update_device(struct device *dev)
>  					goto abort;
>  				data->target_count[i] = rv;
>  			}
> +
> +			rv = i2c_smbus_read_byte_data(client,
> +					MAX31790_REG_FAN_CONFIG(i));
> +			if (rv < 0)
> +				goto abort;
> +			data->fan_config[i] = rv;

Why is this needed ?

Guenter

>  		}
>  
>  		data->last_updated = jiffies;
> @@ -202,6 +208,9 @@ static int max31790_read_fan(struct device *dev, u32 attr, int channel,
>  		}
>  		mutex_unlock(&data->update_lock);
>  		return 0;
> +	case hwmon_fan_enable:
> +		*val = !!(data->fan_config[channel] & MAX31790_FAN_CFG_TACH_INPUT_EN);
> +		return 0;
>  	default:
>  		return -EOPNOTSUPP;
>  	}
> @@ -214,7 +223,7 @@ static int max31790_write_fan(struct device *dev, u32 attr, int channel,
>  	struct i2c_client *client = data->client;
>  	int target_count;
>  	int err = 0;
> -	u8 bits;
> +	u8 bits, fan_config;
>  	int sr;
>  
>  	mutex_lock(&data->update_lock);
> @@ -243,6 +252,23 @@ static int max31790_write_fan(struct device *dev, u32 attr, int channel,
>  					MAX31790_REG_TARGET_COUNT(channel),
>  					data->target_count[channel]);
>  		break;
> +	case hwmon_fan_enable:
> +		fan_config = data->fan_config[channel];
> +		if (val == 0) {
> +			fan_config &= ~MAX31790_FAN_CFG_TACH_INPUT_EN;
> +		} else if (val == 1) {
> +			fan_config |= MAX31790_FAN_CFG_TACH_INPUT_EN;
> +		} else {
> +			err = -EINVAL;
> +			break;
> +		}
> +		if (fan_config != data->fan_config[channel]) {
> +			err = i2c_smbus_write_byte_data(client, MAX31790_REG_FAN_CONFIG(channel),
> +							fan_config);
> +			if (!err)
> +				data->fan_config[channel] = fan_config;
> +		}
> +		break;
>  	default:
>  		err = -EOPNOTSUPP;
>  		break;
> @@ -270,6 +296,10 @@ static umode_t max31790_fan_is_visible(const void *_data, u32 attr, int channel)
>  		    !(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
>  			return 0644;
>  		return 0;
> +	case hwmon_fan_enable:
> +		if (channel < NR_CHANNEL)
> +			return 0644;
> +		return 0;
>  	default:
>  		return 0;
>  	}
> @@ -423,12 +453,12 @@ static umode_t max31790_is_visible(const void *data,
>  
>  static const struct hwmon_channel_info *max31790_info[] = {
>  	HWMON_CHANNEL_INFO(fan,
> -			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> -			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> -			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> -			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> -			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> -			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> +			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
> +			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
> +			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
> +			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
> +			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
> +			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
>  			   HWMON_F_INPUT | HWMON_F_FAULT,
>  			   HWMON_F_INPUT | HWMON_F_FAULT,
>  			   HWMON_F_INPUT | HWMON_F_FAULT,
> -- 
> 2.37.2.672.g94769d06f0-goog
>