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Date: Wed, 12 Jun 2024 08:55:45 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Naresh Solanki <naresh.solanki@...ements.com>,
Jean Delvare <jdelvare@...e.com>
Cc: linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/2] hwmon: (max6639) : Add hwmon attributes for fan
and pwm
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@...ements.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 |
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