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    Subject[PATCH V2 7/9] hwmon: pwm-fan: add sysfs node to read rpm of fan
    Date
    Add fan device attribute fan1_input in pwm-fan driver
    to read speed of fan in rotations per minute.

    Signed-off-by: Rajkumar Rampelli <rrajk@nvidia.com>
    ---

    V2: Removed generic-pwm-tachometer driver and using pwm-fan driver as per suggestions
    to read fan speed.
    Added fan device attribute to report speed of fan in rpms through hwmon sysfs.

    drivers/hwmon/pwm-fan.c | 23 +++++++++++++++++++++++
    1 file changed, 23 insertions(+)

    diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
    index 70cc0d1..8dda209 100644
    --- a/drivers/hwmon/pwm-fan.c
    +++ b/drivers/hwmon/pwm-fan.c
    @@ -98,11 +98,34 @@ static ssize_t show_pwm(struct device *dev,
    return sprintf(buf, "%u\n", ctx->pwm_value);
    }

    +static ssize_t show_rpm(struct device *dev, struct device_attribute *attr,
    + char *buf)
    +{
    + struct pwm_fan_ctx *ptt = dev_get_drvdata(dev);
    + struct pwm_device *pwm = ptt->pwm;
    + struct pwm_capture result;
    + unsigned int rpm = 0;
    + int ret;
    +
    + ret = pwm_capture(pwm, &result, 0);
    + if (ret < 0) {
    + pr_err("Failed to capture PWM: %d\n", ret);
    + return ret;
    + }
    +
    + if (result.period)
    + rpm = DIV_ROUND_CLOSEST_ULL(60ULL * NSEC_PER_SEC,
    + result.period);
    +
    + return sprintf(buf, "%u\n", rpm);
    +}

    static SENSOR_DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm, 0);
    +static SENSOR_DEVICE_ATTR(fan1_input, 0444, show_rpm, NULL, 0);

    static struct attribute *pwm_fan_attrs[] = {
    &sensor_dev_attr_pwm1.dev_attr.attr,
    + &sensor_dev_attr_fan1_input.dev_attr.attr,
    NULL,
    };

    --
    2.1.4
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