hwmon: (adt7475) Add support for configuring initial PWM state

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@alliedtelesis.co.nz>
Link: https://lore.kernel.org/r/20240722221737.3407958-4-chris.packham@alliedtelesis.co.nz
[groeck: Cleaned up formatting]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

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 +1664,130 @@ 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_args(u32 args[4], struct adt7475_pwm_config *cfg)
+{
+	int freq_hz;
+	int duty;
+
+	if (args[1] == 0)
+		return -EINVAL;
+
+	freq_hz = 1000000000UL / args[1];
+	if (args[3] >= args[1])
+		duty = 255;
+	else
+		duty = div_u64(255ULL * args[3], args[1]);
+
+	cfg->index = args[0];
+	cfg->freq = find_closest(freq_hz, pwmfreq_table, ARRAY_SIZE(pwmfreq_table));
+	cfg->flags = args[2];
+	cfg->duty = duty;
+
+	return 0;
+}
+
+static int adt7475_pwm_properties_parse_reference_args(struct fwnode_handle *fwnode,
+						       struct adt7475_pwm_config *cfg)
+{
+	int ret, i;
+	struct fwnode_reference_args rargs = {};
+	u32 args[4] = {};
+
+	ret = fwnode_property_get_reference_args(fwnode, "pwms", "#pwm-cells", 0, 0, &rargs);
+	if (ret)
+		return ret;
+
+	if (rargs.nargs != 4) {
+		fwnode_handle_put(rargs.fwnode);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < 4; i++)
+		args[i] = rargs.args[i];
+
+	ret = _adt7475_pwm_properties_parse_args(args, cfg);
+
+	fwnode_handle_put(rargs.fwnode);
+
+	return ret;
+}
+
+static int adt7475_pwm_properties_parse_args(struct fwnode_handle *fwnode,
+					     struct adt7475_pwm_config *cfg)
+{
+	int ret;
+	u32 args[4] = {};
+
+	ret = fwnode_property_read_u32_array(fwnode, "pwms", args, ARRAY_SIZE(args));
+	if (ret)
+		return ret;
+
+	return _adt7475_pwm_properties_parse_args(args, cfg);
+}
+
+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;
@@ -1774,6 +1900,10 @@ 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: