acpi: Store CRC-32 hash of the _PLD in struct acpi_device

Storing CRC-32 hash of the Physical Location of Device
object (_PLD) with devices that have it. The hash is stored
to a new struct acpi_device member "pld_crc".

The hash makes it easier to find devices that share a
location, as there is no need to evaluate the entire object
every time. Knowledge about devices that share a location
can be used in device drivers that need to know the
connections to other components inside a system. USB3 ports
will for example always share their location with a USB2
port.

Acked-by: Rafael J. Wysocki <[email protected]>
Signed-off-by: Heikki Krogerus <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Heikki Krogerus

drivers/acpi/scan.c

@@ -19,6 +19,7 @@
 #include <linux/dma-map-ops.h>
 #include <linux/platform_data/x86/apple.h>
 #include <linux/pgtable.h>
+#include <linux/crc32.h>
 
 #include "internal.h"
 
@@ -654,6 +655,19 @@ static int acpi_tie_acpi_dev(struct acpi_device *adev)
 	return 0;
 }
 
+static void acpi_store_pld_crc(struct acpi_device *adev)
+{
+	struct acpi_pld_info *pld;
+	acpi_status status;
+
+	status = acpi_get_physical_device_location(adev->handle, &pld);
+	if (ACPI_FAILURE(status))
+		return;
+
+	adev->pld_crc = crc32(~0, pld, sizeof(*pld));
+	ACPI_FREE(pld);
+}
+
 static int __acpi_device_add(struct acpi_device *device,
 			     void (*release)(struct device *))
 {
@@ -712,6 +726,8 @@ static int __acpi_device_add(struct acpi_device *device,
 	if (device->wakeup.flags.valid)
 		list_add_tail(&device->wakeup_list, &acpi_wakeup_device_list);
 
+	acpi_store_pld_crc(device);
+
 	mutex_unlock(&acpi_device_lock);
 
 	if (device->parent)

include/acpi/acpi_bus.h

@@ -358,6 +358,7 @@ struct acpi_gpio_mapping;
 
 /* Device */
 struct acpi_device {
+	u32 pld_crc;
 	int device_type;
 	acpi_handle handle;		/* no handle for fixed hardware */
 	struct fwnode_handle fwnode;