ACPI: fan: Add additional attributes for fine grain control

Add additional attributes, which helps in implementing algorithm in
the user space to optimize fan control. These attributes are presented
in the same directory as the existing performance state attributes.

Additional attributes:

1. Support of fine grain control
Publish support of presence of fine grain control so that fan speed
can be tuned correctly. This attribute is called "fine_grain_control".

2. fan speed
Publish the actual fan rpm in sysfs. Knowing fan rpm is helpful to
reduce noise level and use passive control instead. Also fan performance
may not be same over time, so the same control value may not be enough
to run the fan at a speed. So a feedback value of speed is helpful. This
sysfs attribute is called "fan_speed_rpm".

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: spandruvada

drivers/acpi/fan.h

@@ -48,8 +48,11 @@ struct acpi_fan {
 	struct acpi_fan_fps *fps;
 	int fps_count;
 	struct thermal_cooling_device *cdev;
+	struct device_attribute fst_speed;
+	struct device_attribute fine_grain_control;
 };
 
+int acpi_fan_get_fst(struct acpi_device *device, struct acpi_fan_fst *fst);
 int acpi_fan_create_attributes(struct acpi_device *device);
 void acpi_fan_delete_attributes(struct acpi_device *device);
 #endif

drivers/acpi/fan_attr.c

@@ -49,10 +49,50 @@ static ssize_t show_state(struct device *dev, struct device_attribute *attr, cha
 	return count;
 }
 
+static ssize_t show_fan_speed(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct acpi_device *acpi_dev = container_of(dev, struct acpi_device, dev);
+	struct acpi_fan_fst fst;
+	int status;
+
+	status = acpi_fan_get_fst(acpi_dev, &fst);
+	if (status)
+		return status;
+
+	return sprintf(buf, "%lld\n", fst.speed);
+}
+
+static ssize_t show_fine_grain_control(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct acpi_device *acpi_dev = container_of(dev, struct acpi_device, dev);
+	struct acpi_fan *fan = acpi_driver_data(acpi_dev);
+
+	return sprintf(buf, "%d\n", fan->fif.fine_grain_ctrl);
+}
+
 int acpi_fan_create_attributes(struct acpi_device *device)
 {
 	struct acpi_fan *fan = acpi_driver_data(device);
-	int i, status = 0;
+	int i, status;
+
+	sysfs_attr_init(&fan->fine_grain_control.attr);
+	fan->fine_grain_control.show = show_fine_grain_control;
+	fan->fine_grain_control.store = NULL;
+	fan->fine_grain_control.attr.name = "fine_grain_control";
+	fan->fine_grain_control.attr.mode = 0444;
+	status = sysfs_create_file(&device->dev.kobj, &fan->fine_grain_control.attr);
+	if (status)
+		return status;
+
+	/* _FST is present if we are here */
+	sysfs_attr_init(&fan->fst_speed.attr);
+	fan->fst_speed.show = show_fan_speed;
+	fan->fst_speed.store = NULL;
+	fan->fst_speed.attr.name = "fan_speed_rpm";
+	fan->fst_speed.attr.mode = 0444;
+	status = sysfs_create_file(&device->dev.kobj, &fan->fst_speed.attr);
+	if (status)
+		goto rem_fine_grain_attr;
 
 	for (i = 0; i < fan->fps_count; ++i) {
 		struct acpi_fan_fps *fps = &fan->fps[i];
@@ -69,10 +109,18 @@ int acpi_fan_create_attributes(struct acpi_device *device)
 
 			for (j = 0; j < i; ++j)
 				sysfs_remove_file(&device->dev.kobj, &fan->fps[j].dev_attr.attr);
-			break;
+			goto rem_fst_attr;
 		}
 	}
 
+	return 0;
+
+rem_fst_attr:
+	sysfs_remove_file(&device->dev.kobj, &fan->fst_speed.attr);
+
+rem_fine_grain_attr:
+	sysfs_remove_file(&device->dev.kobj, &fan->fine_grain_control.attr);
+
 	return status;
 }
 
@@ -83,4 +131,7 @@ void acpi_fan_delete_attributes(struct acpi_device *device)
 
 	for (i = 0; i < fan->fps_count; ++i)
 		sysfs_remove_file(&device->dev.kobj, &fan->fps[i].dev_attr.attr);
+
+	sysfs_remove_file(&device->dev.kobj, &fan->fst_speed.attr);
+	sysfs_remove_file(&device->dev.kobj, &fan->fine_grain_control.attr);
 }

drivers/acpi/fan_core.c

@@ -75,7 +75,7 @@ static int fan_get_max_state(struct thermal_cooling_device *cdev, unsigned long
 	return 0;
 }
 
-static int acpi_fan_get_fst(struct acpi_device *device, struct acpi_fan_fst *fst)
+int acpi_fan_get_fst(struct acpi_device *device, struct acpi_fan_fst *fst)
 {
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 	union acpi_object *obj;