[PATCH V2 4/4] usb: Set device removable state based on ACPI USB data

Matthew Garrett
2012-03-12T21:45:47Z

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: Matthew Garrett <mjg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
drivers/usb/core/usb-acpi.c | 56 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 56 insertions(+)

diff --git a/drivers/usb/core/usb-acpi.c b/drivers/usb/core/usb-acpi.c
index cab5cb7..e49373a 100644
--- a/drivers/usb/core/usb-acpi.c
+++ b/drivers/usb/core/usb-acpi.c
@@ -19,6 +19,53 @@

#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 +87,15 @@ 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;
}

--
1.7.9.3

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