drm/radeon: Add sclk frequency as hwmon sensor

This patch adds support for reporting sclk values for Radeon GPUs, where supported.
Signed-off-by: Sandeep Raghuraman <sandy.8925@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_pm.c

@@ -712,6 +712,31 @@ static SENSOR_DEVICE_ATTR(pwm1_enable, S_IRUGO | S_IWUSR, radeon_hwmon_get_pwm1_
 static SENSOR_DEVICE_ATTR(pwm1_min, S_IRUGO, radeon_hwmon_get_pwm1_min, NULL, 0);
 static SENSOR_DEVICE_ATTR(pwm1_max, S_IRUGO, radeon_hwmon_get_pwm1_max, NULL, 0);
 
+static ssize_t radeon_hwmon_show_sclk(struct device *dev,
+				      struct device_attribute *attr, char *buf)
+{
+	struct radeon_device *rdev = dev_get_drvdata(dev);
+	struct drm_device *ddev = rdev->ddev;
+	u32 sclk = 0;
+
+	/* Can't get clock frequency when the card is off */
+	if ((rdev->flags & RADEON_IS_PX) &&
+	    (ddev->switch_power_state != DRM_SWITCH_POWER_ON))
+		return -EINVAL;
+
+	if (rdev->asic->dpm.get_current_sclk)
+		sclk = radeon_dpm_get_current_sclk(rdev);
+
+	/* Value returned by dpm is in 10 KHz units, need to convert it into Hz 
+	   for hwmon */
+	sclk *= 10000;
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", sclk);
+}
+
+static SENSOR_DEVICE_ATTR(freq1_input, S_IRUGO, radeon_hwmon_show_sclk, NULL,
+			  0);
+
 
 static struct attribute *hwmon_attributes[] = {
 	&sensor_dev_attr_temp1_input.dev_attr.attr,
@@ -721,6 +746,7 @@ static struct attribute *hwmon_attributes[] = {
 	&sensor_dev_attr_pwm1_enable.dev_attr.attr,
 	&sensor_dev_attr_pwm1_min.dev_attr.attr,
 	&sensor_dev_attr_pwm1_max.dev_attr.attr,
+	&sensor_dev_attr_freq1_input.dev_attr.attr,
 	NULL
 };
 
@@ -738,7 +764,8 @@ static umode_t hwmon_attributes_visible(struct kobject *kobj,
 	     attr == &sensor_dev_attr_pwm1.dev_attr.attr ||
 	     attr == &sensor_dev_attr_pwm1_enable.dev_attr.attr ||
 	     attr == &sensor_dev_attr_pwm1_max.dev_attr.attr ||
-	     attr == &sensor_dev_attr_pwm1_min.dev_attr.attr))
+	     attr == &sensor_dev_attr_pwm1_min.dev_attr.attr ||
+	     attr == &sensor_dev_attr_freq1_input.dev_attr.attr))
 		return 0;
 
 	/* Skip fan attributes if fan is not present */