[PATCH 2/3] hwmon: (adt7475) fan stall prevention

Chris Packham
2017-05-02T05:46:07Z

By default adt7475 will stop the fans (pwm duty cycle 0%) when the
temperature drops past Tmin - hysteresis. Some systems want to keep the
fans moving even when the temperature drops so add new sysfs attributes
that configure the enhanced acoustics min 1-3 which allows the fans to
run at the minimum configure pwm duty cycle.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
pwmN_min is a horrible name but I really can't think of anything better.
I'm biased a little because that is essentially the name of the bits in
the datasheet. I'm open to suggestions.

Documentation/hwmon/adt7475 | 5 +++++
drivers/hwmon/adt7475.c | 50 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 55 insertions(+)

diff --git a/Documentation/hwmon/adt7475 b/Documentation/hwmon/adt7475
index 0502f2b464e1..85dc9e17bdee 100644
--- a/Documentation/hwmon/adt7475
+++ b/Documentation/hwmon/adt7475
@@ -109,6 +109,11 @@ fan speed) is applied. PWM values range from 0 (off) to 255 (full speed).
Fan speed may be set to maximum when the temperature sensor associated with
the PWM control exceeds temp#_max.

+At Tmin - hysteresis the PWM output can either be off (0% duty cycle) or
+at the minimum (i.e. auto_point1_pwm). This can be configured using the
+pwm[1-*]_min sysfs attribute. A value of 0 means the fans will shut off. A
+value of 1 means the fans will run at auto_point1_pwm.
+
Notes
-----

diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
index ec0c43fbcdce..53f25bda0919 100644
--- a/drivers/hwmon/adt7475.c
+++ b/drivers/hwmon/adt7475.c
@@ -79,6 +79,9 @@

#define REG_TEMP_TRANGE_BASE 0x5F

+#define REG_ENHANCE_ACOUSTICS1 0x62
+#define REG_ENHANCE_ACOUSTICS2 0x63
+
#define REG_PWM_MIN_BASE 0x64

#define REG_TEMP_TMIN_BASE 0x67
@@ -209,6 +212,7 @@ struct adt7475_data {
u8 range[3];
u8 pwmctl[3];
u8 pwmchan[3];
+ u8 enh_acou[2];

u8 vid;
u8 vrm;
@@ -700,6 +704,43 @@ static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
data->pwm[sattr->nr][sattr->index] = clamp_val(val, 0, 0xFF);
i2c_smbus_write_byte_data(client, reg,
data->pwm[sattr->nr][sattr->index]);
+ mutex_unlock(&data->lock);
+
+ return count;
+}
+
+
+static ssize_t show_pwm_min(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
+ struct i2c_client *client = to_i2c_client(dev);
+ struct adt7475_data *data = i2c_get_clientdata(client);
+ u8 mask = BIT(5 + sattr->index);
+
+ return sprintf(buf, "%d\n", !!(data->enh_acou[0] & mask));
+}
+
+static ssize_t set_pwm_min(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
+ struct i2c_client *client = to_i2c_client(dev);
+ struct adt7475_data *data = i2c_get_clientdata(client);
+ long val;
+ u8 mask = BIT(5 + sattr->index);
+
+ if (kstrtol(buf, 10, &val))
+ return -EINVAL;
+
+ mutex_lock(&data->lock);
+
+ data->enh_acou[0] &= ~mask;
+ if (val)
+ data->enh_acou[0] |= mask;
+
+ i2c_smbus_write_byte_data(client, REG_ENHANCE_ACOUSTICS1,
+ data->enh_acou[0]);

mutex_unlock(&data->lock);

@@ -1028,6 +1069,8 @@ static SENSOR_DEVICE_ATTR_2(pwm1_auto_point1_pwm, S_IRUGO | S_IWUSR, show_pwm,
set_pwm, MIN, 0);
static SENSOR_DEVICE_ATTR_2(pwm1_auto_point2_pwm, S_IRUGO | S_IWUSR, show_pwm,
set_pwm, MAX, 0);
+static SENSOR_DEVICE_ATTR_2(pwm1_min, S_IRUGO | S_IWUSR, show_pwm_min,
+ set_pwm_min, 0, 0);
static SENSOR_DEVICE_ATTR_2(pwm2, S_IRUGO | S_IWUSR, show_pwm, set_pwm, INPUT,
1);
static SENSOR_DEVICE_ATTR_2(pwm2_freq, S_IRUGO | S_IWUSR, show_pwmfreq,
@@ -1040,6 +1083,8 @@ static SENSOR_DEVICE_ATTR_2(pwm2_auto_point1_pwm, S_IRUGO | S_IWUSR, show_pwm,
set_pwm, MIN, 1);
static SENSOR_DEVICE_ATTR_2(pwm2_auto_point2_pwm, S_IRUGO | S_IWUSR, show_pwm,
set_pwm, MAX, 1);
+static SENSOR_DEVICE_ATTR_2(pwm2_min, S_IRUGO | S_IWUSR, show_pwm_min,
+ set_pwm_min, 0, 1);
static SENSOR_DEVICE_ATTR_2(pwm3, S_IRUGO | S_IWUSR, show_pwm, set_pwm, INPUT,
2);
static SENSOR_DEVICE_ATTR_2(pwm3_freq, S_IRUGO | S_IWUSR, show_pwmfreq,
@@ -1052,6 +1097,8 @@ static SENSOR_DEVICE_ATTR_2(pwm3_auto_point1_pwm, S_IRUGO | S_IWUSR, show_pwm,
set_pwm, MIN, 2);
static SENSOR_DEVICE_ATTR_2(pwm3_auto_point2_pwm, S_IRUGO | S_IWUSR, show_pwm,
set_pwm, MAX, 2);
+static SENSOR_DEVICE_ATTR_2(pwm3_min, S_IRUGO | S_IWUSR, show_pwm_min,
+ set_pwm_min, 0, 2);

/* Non-standard name, might need revisiting */
static DEVICE_ATTR_RW(pwm_use_point2_pwm_at_crit);
@@ -1112,12 +1159,14 @@ static struct attribute *adt7475_attrs[] = {
&sensor_dev_attr_pwm1_auto_channels_temp.dev_attr.attr,
&sensor_dev_attr_pwm1_auto_point1_pwm.dev_attr.attr,
&sensor_dev_attr_pwm1_auto_point2_pwm.dev_attr.attr,
+ &sensor_dev_attr_pwm1_min.dev_attr.attr,
&sensor_dev_attr_pwm3.dev_attr.attr,
&sensor_dev_attr_pwm3_freq.dev_attr.attr,
&sensor_dev_attr_pwm3_enable.dev_attr.attr,
&sensor_dev_attr_pwm3_auto_channels_temp.dev_attr.attr,
&sensor_dev_attr_pwm3_auto_point1_pwm.dev_attr.attr,
&sensor_dev_attr_pwm3_auto_point2_pwm.dev_attr.attr,
+ &sensor_dev_attr_pwm3_min.dev_attr.attr,
&dev_attr_pwm_use_point2_pwm_at_crit.attr,
NULL,
};
@@ -1136,6 +1185,7 @@ static struct attribute *pwm2_attrs[] = {
&sensor_dev_attr_pwm2_auto_channels_temp.dev_attr.attr,
&sensor_dev_attr_pwm2_auto_point1_pwm.dev_attr.attr,
&sensor_dev_attr_pwm2_auto_point2_pwm.dev_attr.attr,
+ &sensor_dev_attr_pwm2_min.dev_attr.attr,
NULL
};

--
2.11.0.24.ge6920cf