hwmon: (adt7470) Expose PWM frequency to sysfs

The ADT7470 supports a variety of PWM frequencies. This patch allows the
frequency to be configured and viewed through the sysfs entry pwm1_freq.

Signed-off-by: Joshua Scott <joshua.scott@alliedtelesis.co.nz>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/Documentation/hwmon/adt7470 b/Documentation/hwmon/adt7470
index 8ce4aa0..fe68e18 100644 (file)
--- a/Documentation/hwmon/adt7470
+++ b/Documentation/hwmon/adt7470
@@ -65,6 +65,23 @@ from 0 (off) to 255 (full speed).  Fan speed will be set to maximum when the
 temperature sensor associated with the PWM control exceeds
 pwm#_auto_point2_temp.
 
+The driver also allows control of the PWM frequency:
+
+* pwm1_freq
+
+The PWM frequency is rounded to the nearest one of:
+
+* 11.0 Hz
+* 14.7 Hz
+* 22.1 Hz
+* 29.4 Hz
+* 35.3 Hz
+* 44.1 Hz
+* 58.8 Hz
+* 88.2 Hz
+* 1.4 kHz
+* 22.5 kHz
+
 Notes
 -----
 

diff --git a/drivers/hwmon/adt7470.c b/drivers/hwmon/adt7470.c
index f5da39a..94550d7 100644 (file)
--- a/drivers/hwmon/adt7470.c
+++ b/drivers/hwmon/adt7470.c
@@ -32,6 +32,7 @@
 #include <linux/log2.h>
 #include <linux/kthread.h>
 #include <linux/slab.h>
+#include <linux/util_macros.h>
 
 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x2C, 0x2E, 0x2F, I2C_CLIENT_END };
@@ -83,6 +84,7 @@ static const unsigned short normal_i2c[] = { 0x2C, 0x2E, 0x2F, I2C_CLIENT_END };
 #define ADT7470_REG_PWM_MIN_MAX_ADDR           0x6D
 #define ADT7470_REG_PWM_TEMP_MIN_BASE_ADDR     0x6E
 #define ADT7470_REG_PWM_TEMP_MIN_MAX_ADDR      0x71
+#define ADT7470_REG_CFG_2                      0x74
 #define ADT7470_REG_ACOUSTICS12                        0x75
 #define ADT7470_REG_ACOUSTICS34                        0x76
 #define ADT7470_REG_DEVICE                     0x3D
@@ -142,6 +144,11 @@ static const unsigned short normal_i2c[] = { 0x2C, 0x2E, 0x2F, I2C_CLIENT_END };
 #define FAN_PERIOD_INVALID     65535
 #define FAN_DATA_VALID(x)      ((x) && (x) != FAN_PERIOD_INVALID)
 
+/* Config registers 1 and 2 include fields for selecting the PWM frequency */
+#define ADT7470_CFG_LF         0x40
+#define ADT7470_FREQ_MASK      0x70
+#define ADT7470_FREQ_SHIFT     4
+
 struct adt7470_data {
        struct i2c_client       *client;
        struct mutex            lock;
@@ -688,6 +695,70 @@ static ssize_t set_pwm(struct device *dev, struct device_attribute *devattr,
        return count;
 }
 
+/* These are the valid PWM frequencies to the nearest Hz */
+static const int adt7470_freq_map[] = {
+       11, 15, 22, 29, 35, 44, 59, 88, 1400, 22500
+};
+
+static ssize_t show_pwm_freq(struct device *dev,
+                            struct device_attribute *devattr, char *buf)
+{
+       struct adt7470_data *data = adt7470_update_device(dev);
+       unsigned char cfg_reg_1;
+       unsigned char cfg_reg_2;
+       int index;
+
+       mutex_lock(&data->lock);
+       cfg_reg_1 = i2c_smbus_read_byte_data(data->client, ADT7470_REG_CFG);
+       cfg_reg_2 = i2c_smbus_read_byte_data(data->client, ADT7470_REG_CFG_2);
+       mutex_unlock(&data->lock);
+
+       index = (cfg_reg_2 & ADT7470_FREQ_MASK) >> ADT7470_FREQ_SHIFT;
+       if (!(cfg_reg_1 & ADT7470_CFG_LF))
+               index += 8;
+       if (index >= ARRAY_SIZE(adt7470_freq_map))
+               index = ARRAY_SIZE(adt7470_freq_map) - 1;
+
+       return scnprintf(buf, PAGE_SIZE, "%d\n", adt7470_freq_map[index]);
+}
+
+static ssize_t set_pwm_freq(struct device *dev,
+                           struct device_attribute *devattr,
+                           const char *buf, size_t count)
+{
+       struct adt7470_data *data = dev_get_drvdata(dev);
+       struct i2c_client *client = data->client;
+       long freq;
+       int index;
+       int low_freq = ADT7470_CFG_LF;
+       unsigned char val;
+
+       if (kstrtol(buf, 10, &freq))
+               return -EINVAL;
+
+       /* Round the user value given to the closest available frequency */
+       index = find_closest(freq, adt7470_freq_map,
+                            ARRAY_SIZE(adt7470_freq_map));
+
+       if (index >= 8) {
+               index -= 8;
+               low_freq = 0;
+       }
+
+       mutex_lock(&data->lock);
+       /* Configuration Register 1 */
+       val = i2c_smbus_read_byte_data(client, ADT7470_REG_CFG);
+       i2c_smbus_write_byte_data(client, ADT7470_REG_CFG,
+                                 (val & ~ADT7470_CFG_LF) | low_freq);
+       /* Configuration Register 2 */
+       val = i2c_smbus_read_byte_data(client, ADT7470_REG_CFG_2);
+       i2c_smbus_write_byte_data(client, ADT7470_REG_CFG_2,
+               (val & ~ADT7470_FREQ_MASK) | (index << ADT7470_FREQ_SHIFT));
+       mutex_unlock(&data->lock);
+
+       return count;
+}
+
 static ssize_t show_pwm_max(struct device *dev,
                            struct device_attribute *devattr,
                            char *buf)
@@ -1038,6 +1109,8 @@ static SENSOR_DEVICE_ATTR(pwm2, S_IWUSR | S_IRUGO, show_pwm, set_pwm, 1);
 static SENSOR_DEVICE_ATTR(pwm3, S_IWUSR | S_IRUGO, show_pwm, set_pwm, 2);
 static SENSOR_DEVICE_ATTR(pwm4, S_IWUSR | S_IRUGO, show_pwm, set_pwm, 3);
 
+static DEVICE_ATTR(pwm1_freq, S_IWUSR | S_IRUGO, show_pwm_freq, set_pwm_freq);
+
 static SENSOR_DEVICE_ATTR(pwm1_auto_point1_pwm, S_IWUSR | S_IRUGO,
                    show_pwm_min, set_pwm_min, 0);
 static SENSOR_DEVICE_ATTR(pwm2_auto_point1_pwm, S_IWUSR | S_IRUGO,
@@ -1154,6 +1227,7 @@ static struct attribute *adt7470_attrs[] = {
        &sensor_dev_attr_fan4_alarm.dev_attr.attr,
        &sensor_dev_attr_force_pwm_max.dev_attr.attr,
        &sensor_dev_attr_pwm1.dev_attr.attr,
+       &dev_attr_pwm1_freq.attr,
        &sensor_dev_attr_pwm2.dev_attr.attr,
        &sensor_dev_attr_pwm3.dev_attr.attr,
        &sensor_dev_attr_pwm4.dev_attr.attr,