hwmon/it87: Add PWM base frequency control

Let the user select the base PWM frequency when using the it87
hardware monitoring driver. Different frequencies can give better
control on some fans.

Also update the documentation to mention the PWM frequency control
files, with misc cleanups to the PWM section.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 54 insertions, 2 deletions

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index 1ed8b7e2c35d..bb16668ad2bd 100644
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -202,6 +202,17 @@ static int DIV_TO_REG(int val)
 }
 #define DIV_FROM_REG(val) (1 << (val))
 
+static const unsigned int pwm_freq[8] = {
+	48000000 / 128,
+	24000000 / 128,
+	12000000 / 128,
+	8000000 / 128,
+	6000000 / 128,
+	3000000 / 128,
+	1500000 / 128,
+	750000 / 128,
+};
+
 
 /* For each registered IT87, we need to keep some data in memory. That
    data is pointed to by it87_list[NR]->data. The structure itself is
@@ -232,6 +243,7 @@ struct it87_data {
 	u8 vrm;
 	u32 alarms;		/* Register encoding, combined */
 	u8 fan_main_ctrl;	/* Register value */
+	u8 fan_ctl;		/* Register value */
 	u8 manual_pwm_ctl[3];   /* manual PWM value set by user */
 };
 
@@ -519,6 +531,14 @@ static ssize_t show_pwm(struct device *dev, struct device_attribute *attr,
 	struct it87_data *data = it87_update_device(dev);
 	return sprintf(buf,"%d\n", data->manual_pwm_ctl[nr]);
 }
+static ssize_t show_pwm_freq(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct it87_data *data = it87_update_device(dev);
+	int index = (data->fan_ctl >> 4) & 0x07;
+
+	return sprintf(buf, "%u\n", pwm_freq[index]);
+}
 static ssize_t set_fan_min(struct device *dev, struct device_attribute *attr,
 		const char *buf, size_t count)
 {
@@ -639,6 +659,28 @@ static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
 	mutex_unlock(&data->update_lock);
 	return count;
 }
+static ssize_t set_pwm_freq(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct it87_data *data = i2c_get_clientdata(client);
+	unsigned long val = simple_strtoul(buf, NULL, 10);
+	int i;
+
+	/* Search for the nearest available frequency */
+	for (i = 0; i < 7; i++) {
+		if (val > (pwm_freq[i] + pwm_freq[i+1]) / 2)
+			break;
+	}
+
+	mutex_lock(&data->update_lock);
+	data->fan_ctl = it87_read_value(client, IT87_REG_FAN_CTL) & 0x8f;
+	data->fan_ctl |= i << 4;
+	it87_write_value(client, IT87_REG_FAN_CTL, data->fan_ctl);
+	mutex_unlock(&data->update_lock);
+
+	return count;
+}
 
 #define show_fan_offset(offset)					\
 static SENSOR_DEVICE_ATTR(fan##offset##_input, S_IRUGO,		\
@@ -656,7 +698,10 @@ show_fan_offset(3);
 static SENSOR_DEVICE_ATTR(pwm##offset##_enable, S_IRUGO | S_IWUSR,	\
 		show_pwm_enable, set_pwm_enable, offset - 1);		\
 static SENSOR_DEVICE_ATTR(pwm##offset, S_IRUGO | S_IWUSR,		\
-		show_pwm, set_pwm, offset - 1);
+		show_pwm, set_pwm, offset - 1);				\
+static DEVICE_ATTR(pwm##offset##_freq,					\
+		(offset == 1 ? S_IRUGO | S_IWUSR : S_IRUGO),		\
+		show_pwm_freq, (offset == 1 ? set_pwm_freq : NULL));
 
 show_pwm_offset(1);
 show_pwm_offset(2);
@@ -1021,7 +1066,13 @@ static int it87_detect(struct i2c_adapter *adapter)
 		 || (err = device_create_file(&new_client->dev,
 		     &sensor_dev_attr_pwm2.dev_attr))
 		 || (err = device_create_file(&new_client->dev,
-		     &sensor_dev_attr_pwm3.dev_attr)))
+		     &sensor_dev_attr_pwm3.dev_attr))
+		 || (err = device_create_file(&new_client->dev,
+		     &dev_attr_pwm1_freq))
+		 || (err = device_create_file(&new_client->dev,
+		     &dev_attr_pwm2_freq))
+		 || (err = device_create_file(&new_client->dev,
+		     &dev_attr_pwm3_freq)))
 			goto ERROR4;
 	}
 
@@ -1316,6 +1367,7 @@ static struct it87_data *it87_update_device(struct device *dev)
 			(it87_read_value(client, IT87_REG_ALARM2) << 8) |
 			(it87_read_value(client, IT87_REG_ALARM3) << 16);
 		data->fan_main_ctrl = it87_read_value(client, IT87_REG_FAN_MAIN_CTRL);
+		data->fan_ctl = it87_read_value(client, IT87_REG_FAN_CTL);
 
 		data->sensor = it87_read_value(client, IT87_REG_TEMP_ENABLE);
 		/* The 8705 does not have VID capability */