driver core: Add sysfs support for physical location of a device

When ACPI table includes _PLD fields for a device, create a new
directory (physical_location) in sysfs to share _PLD fields.

Currently without PLD information, when there are multiple of same
devices, it is hard to distinguish which device corresponds to which
physical device at which location. For example, when there are two Type
C connectors, it is hard to find out which connector corresponds to the
Type C port on the left panel versus the Type C port on the right panel.
With PLD information provided, we can determine which specific device at
which location is doing what.

_PLD output includes much more fields, but only generic fields are added
and exposed to sysfs, so that non-ACPI devices can also support it in
the future. The minimal generic fields needed for locating a device are
the following.
- panel
- vertical_position
- horizontal_position
- dock
- lid

Signed-off-by: Won Chung <wonchung@google.com>
Link: https://lore.kernel.org/r/20220314195458.271430-1-wonchung@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 73 insertions, 0 deletions

diff --git a/include/linux/device.h b/include/linux/device.h
index 93459724dcde..766fbea6ca83 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -387,6 +387,75 @@ struct dev_msi_info {
 };
 
 /**
+ * enum device_physical_location_panel - Describes which panel surface of the
+ * system's housing the device connection point resides on.
+ * @DEVICE_PANEL_TOP: Device connection point is on the top panel.
+ * @DEVICE_PANEL_BOTTOM: Device connection point is on the bottom panel.
+ * @DEVICE_PANEL_LEFT: Device connection point is on the left panel.
+ * @DEVICE_PANEL_RIGHT: Device connection point is on the right panel.
+ * @DEVICE_PANEL_FRONT: Device connection point is on the front panel.
+ * @DEVICE_PANEL_BACK: Device connection point is on the back panel.
+ * @DEVICE_PANEL_UNKNOWN: The panel with device connection point is unknown.
+ */
+enum device_physical_location_panel {
+	DEVICE_PANEL_TOP,
+	DEVICE_PANEL_BOTTOM,
+	DEVICE_PANEL_LEFT,
+	DEVICE_PANEL_RIGHT,
+	DEVICE_PANEL_FRONT,
+	DEVICE_PANEL_BACK,
+	DEVICE_PANEL_UNKNOWN,
+};
+
+/**
+ * enum device_physical_location_vertical_position - Describes vertical
+ * position of the device connection point on the panel surface.
+ * @DEVICE_VERT_POS_UPPER: Device connection point is at upper part of panel.
+ * @DEVICE_VERT_POS_CENTER: Device connection point is at center part of panel.
+ * @DEVICE_VERT_POS_LOWER: Device connection point is at lower part of panel.
+ */
+enum device_physical_location_vertical_position {
+	DEVICE_VERT_POS_UPPER,
+	DEVICE_VERT_POS_CENTER,
+	DEVICE_VERT_POS_LOWER,
+};
+
+/**
+ * enum device_physical_location_horizontal_position - Describes horizontal
+ * position of the device connection point on the panel surface.
+ * @DEVICE_HORI_POS_LEFT: Device connection point is at left part of panel.
+ * @DEVICE_HORI_POS_CENTER: Device connection point is at center part of panel.
+ * @DEVICE_HORI_POS_RIGHT: Device connection point is at right part of panel.
+ */
+enum device_physical_location_horizontal_position {
+	DEVICE_HORI_POS_LEFT,
+	DEVICE_HORI_POS_CENTER,
+	DEVICE_HORI_POS_RIGHT,
+};
+
+/**
+ * struct device_physical_location - Device data related to physical location
+ * of the device connection point.
+ * @panel: Panel surface of the system's housing that the device connection
+ *         point resides on.
+ * @vertical_position: Vertical position of the device connection point within
+ *                     the panel.
+ * @horizontal_position: Horizontal position of the device connection point
+ *                       within the panel.
+ * @dock: Set if the device connection point resides in a docking station or
+ *        port replicator.
+ * @lid: Set if this device connection point resides on the lid of laptop
+ *       system.
+ */
+struct device_physical_location {
+	enum device_physical_location_panel panel;
+	enum device_physical_location_vertical_position vertical_position;
+	enum device_physical_location_horizontal_position horizontal_position;
+	bool dock;
+	bool lid;
+};
+
+/**
  * struct device - The basic device structure
  * @parent:	The device's "parent" device, the device to which it is attached.
  * 		In most cases, a parent device is some sort of bus or host
@@ -453,6 +522,8 @@ struct dev_msi_info {
  * 		device (i.e. the bus driver that discovered the device).
  * @iommu_group: IOMMU group the device belongs to.
  * @iommu:	Per device generic IOMMU runtime data
+ * @physical_location: Describes physical location of the device connection
+ *		point in the system housing.
  * @removable:  Whether the device can be removed from the system. This
  *              should be set by the subsystem / bus driver that discovered
  *              the device.
@@ -567,6 +638,8 @@ struct device {
 	struct iommu_group	*iommu_group;
 	struct dev_iommu	*iommu;
 
+	struct device_physical_location *physical_location;
+
 	enum device_removable	removable;
 
 	bool			offline_disabled:1;