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Commit 54d3f8c6 authored by Matthew Garrett's avatar Matthew Garrett Committed by Greg Kroah-Hartman
Browse files

usb: Set device removable state based on ACPI USB data 



ACPI offers two methods that allow us to infer whether or not a USB port
is removable. The _PLD method gives us information on whether the port is
"user visible" or not. If that's not present then we can fall back to the
_UPC method which tells us whether or not a port is connectable.

Signed-off-by: default avatarMatthew Garrett <mjg@redhat.com>
Signed-off-by: default avatarLan Tianyu <tianyu.lan@intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent da0af6e7

drivers/usb/core/usb-acpi.c

+57 −0
Original line number Diff line number Diff line
@@ -19,6 +19,54 @@ 


#include "usb.h"



static int usb_acpi_check_upc(struct usb_device *udev, acpi_handle handle)

{

	acpi_status status;

	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

	union acpi_object *upc;

	int ret = 0;



	status = acpi_evaluate_object(handle, "_UPC", NULL, &buffer);



	if (ACPI_FAILURE(status))

		return -ENODEV;



	upc = buffer.pointer;



	if (!upc || (upc->type != ACPI_TYPE_PACKAGE)

		|| upc->package.count != 4) {

		ret = -EINVAL;

		goto out;

	}



	if (upc->package.elements[0].integer.value)

		udev->removable = USB_DEVICE_REMOVABLE;

	else

		udev->removable = USB_DEVICE_FIXED;



out:

	kfree(upc);

	return ret;

}



static int usb_acpi_check_pld(struct usb_device *udev, acpi_handle handle)

{

	acpi_status status;

	struct acpi_pld pld;



	status = acpi_get_physical_device_location(handle, &pld);



	if (ACPI_FAILURE(status))

		return -ENODEV;



	if (pld.user_visible)

		udev->removable = USB_DEVICE_REMOVABLE;

	else

		udev->removable = USB_DEVICE_FIXED;



	return 0;

}



static int usb_acpi_find_device(struct device *dev, acpi_handle *handle)

{

	struct usb_device *udev;
@@ -40,6 +88,15 @@ static int usb_acpi_find_device(struct device *dev, acpi_handle *handle) 
	if (!*handle)

		return -ENODEV;



	/*

	 * PLD will tell us whether a port is removable to the user or

	 * not. If we don't get an answer from PLD (it's not present

	 * or it's malformed) then try to infer it from UPC. If a

	 * device isn't connectable then it's probably not removable.

	 */

	if (usb_acpi_check_pld(udev, *handle) != 0)

		usb_acpi_check_upc(udev, *handle);



	return 0;

}