[PATCH v5 3/3] hwmon: (adt7475) Add support for configuring initial PWM state

[Chris Packham]

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