By default the PWM duty cycle in hardware is 100%. On some systems this
can cause unwanted fan noise. Add the ability to specify the fan
connections and initial state of the PWMs via device properties.
Signed-off-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
---
Notes:
Changes in v3:
- Use the pwm provider/consumer bindings
Changes in v2:
- Use correct device property string for frequency
- Allow -EINVAL and only warn on error
- Use a frequency of 0 to indicate that the hardware should be left as-is
drivers/hwmon/adt7475.c | 63 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 63 insertions(+)
diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
index 4224ffb30483..2b8f39c1d76f 100644
--- a/drivers/hwmon/adt7475.c
+++ b/drivers/hwmon/adt7475.c
@@ -21,6 +21,8 @@
#include <linux/of.h>
#include <linux/util_macros.h>
+#include <dt-bindings/pwm/pwm.h>
+
/* Indexes for the sysfs hooks */
#define INPUT 0
@@ -1662,6 +1664,63 @@ static int adt7475_set_pwm_polarity(struct i2c_client *client)
return 0;
}
+static int adt7475_fan_pwm_config(struct i2c_client *client)
+{
+ struct adt7475_data *data = i2c_get_clientdata(client);
+ struct fwnode_handle *child;
+ struct of_phandle_args args = {};
+ int ret, pwm, duty, freq, flags;
+ u8 val;
+
+ device_for_each_child_node(&client->dev, child) {
+ if (!is_of_node(child))
+ continue;
+
+ ret = of_parse_phandle_with_args(to_of_node(child), "pwms", "#pwm-cells", 0, &args);
+ if (ret)
+ return ret;
+
+ if (args.args_count != 4)
+ return -EINVAL;
+
+ pwm = args.args[0];
+ freq = find_closest(args.args[1], pwmfreq_table, ARRAY_SIZE(pwmfreq_table));
+ flags = args.args[2];
+ duty = clamp_val(args.args[3], 0, 0xFF);
+
+ if (pwm >= ADT7475_PWM_COUNT)
+ return -EINVAL;
+
+ ret = adt7475_read(PWM_CONFIG_REG(pwm));
+ if (ret < 0)
+ return ret;
+ val = ret;
+ if (flags & PWM_POLARITY_INVERTED)
+ val |= BIT(4);
+ else
+ val &= ~BIT(4);
+
+ ret = i2c_smbus_write_byte_data(client, PWM_CONFIG_REG(pwm), val);
+ if (ret)
+ return ret;
+
+ data->pwm[pwm][0] = duty;
+ ret = i2c_smbus_write_byte_data(client, PWM_REG(pwm), data->pwm[pwm][0]);
+ if (ret)
+ return ret;
+
+ data->range[pwm] = adt7475_read(TEMP_TRANGE_REG(pwm));
+ data->range[pwm] &= ~0xf;
+ data->range[pwm] |= freq;
+
+ ret = i2c_smbus_write_byte_data(client, TEMP_TRANGE_REG(pwm), data->range[pwm]);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
static int adt7475_probe(struct i2c_client *client)
{
enum chips chip;
@@ -1778,6 +1837,10 @@ static int adt7475_probe(struct i2c_client *client)
if (ret && ret != -EINVAL)
dev_warn(&client->dev, "Error configuring pwm polarity\n");
+ ret = adt7475_fan_pwm_config(client);
+ if (ret)
+ dev_warn(&client->dev, "Error %d configuring fan/pwm\n", ret);
+
/* Start monitoring */
switch (chip) {
case adt7475:
--
2.45.1
