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 v5:
- Deal with PWM frequency and duty cycle being specified in nanoseconds
Changes in v4:
- Support DT and ACPI fwnodes
- Put PWM into manual mode
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 | 122 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 122 insertions(+)
diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
index 4224ffb30483..5edf423bcb6c 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 +1664,122 @@ static int adt7475_set_pwm_polarity(struct i2c_client *client)
return 0;
}
+struct adt7475_pwm_config {
+ int index;
+ int freq;
+ int flags;
+ int duty;
+};
+
+static int adt7475_pwm_properties_parse_reference_args(struct fwnode_handle *fwnode,
+ struct adt7475_pwm_config *cfg)
+{
+ int ret;
+ struct fwnode_reference_args args = {};
+ int freq_hz;
+ int duty;
+
+ ret = fwnode_property_get_reference_args(fwnode, "pwms", "#pwm-cells", 0, 0, &args);
+ if (ret)
+ return ret;
+
+ if (args.nargs != 4) {
+ fwnode_handle_put(args.fwnode);
+ return -EINVAL;
+ }
+
+ freq_hz = 1000000000UL / args.args[1];
+ duty = 255 / (args.args[1] / args.args[3]);
+
+ cfg->index = args.args[0];
+ cfg->freq = find_closest(freq_hz, pwmfreq_table, ARRAY_SIZE(pwmfreq_table));
+ cfg->flags = args.args[2];
+ cfg->duty = clamp_val(duty, 0, 0xFF);
+
+ fwnode_handle_put(args.fwnode);
+
+ return 0;
+}
+
+static int adt7475_pwm_properties_parse_args(struct fwnode_handle *fwnode,
+ struct adt7475_pwm_config *cfg)
+{
+ int ret;
+ u32 args[4] = {};
+ int freq_hz;
+ int duty;
+
+ ret = fwnode_property_read_u32_array(fwnode, "pwms", args, ARRAY_SIZE(args));
+ if (ret)
+ return ret;
+
+ freq_hz = 1000000000UL / args[1];
+ duty = 255 / (args[1] / args[3]);
+
+ cfg->index = args[0];
+ cfg->freq = find_closest(freq_hz, pwmfreq_table, ARRAY_SIZE(pwmfreq_table));
+ cfg->flags = args[2];
+ cfg->duty = clamp_val(duty, 0, 0xFF);
+
+ 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 adt7475_pwm_config cfg = {};
+ int ret;
+
+ device_for_each_child_node(&client->dev, child) {
+ if (!fwnode_property_present(child, "pwms"))
+ continue;
+
+ if (is_of_node(child))
+ ret = adt7475_pwm_properties_parse_reference_args(child, &cfg);
+ else
+ ret = adt7475_pwm_properties_parse_args(child, &cfg);
+
+ if (cfg.index >= ADT7475_PWM_COUNT)
+ return -EINVAL;
+
+ ret = adt7475_read(PWM_CONFIG_REG(cfg.index));
+ if (ret < 0)
+ return ret;
+ data->pwm[CONTROL][cfg.index] = ret;
+ if (cfg.flags & PWM_POLARITY_INVERTED)
+ data->pwm[CONTROL][cfg.index] |= BIT(4);
+ else
+ data->pwm[CONTROL][cfg.index] &= ~BIT(4);
+
+ /* Force to manual mode so PWM values take effect */
+ data->pwm[CONTROL][cfg.index] &= ~0xE0;
+ data->pwm[CONTROL][cfg.index] |= 0x07 << 5;
+
+ ret = i2c_smbus_write_byte_data(client, PWM_CONFIG_REG(cfg.index),
+ data->pwm[CONTROL][cfg.index]);
+ if (ret)
+ return ret;
+
+ data->pwm[INPUT][cfg.index] = cfg.duty;
+ ret = i2c_smbus_write_byte_data(client, PWM_REG(cfg.index),
+ data->pwm[INPUT][cfg.index]);
+ if (ret)
+ return ret;
+
+ data->range[cfg.index] = adt7475_read(TEMP_TRANGE_REG(cfg.index));
+ data->range[cfg.index] &= ~0xf;
+ data->range[cfg.index] |= cfg.freq;
+
+ ret = i2c_smbus_write_byte_data(client, TEMP_TRANGE_REG(cfg.index),
+ data->range[cfg.index]);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
static int adt7475_probe(struct i2c_client *client)
{
enum chips chip;
@@ -1778,6 +1896,10 @@ 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:
--
2.45.2
