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: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 57 insertions, 0 deletions

diff --git a/drivers/usb/core/usb-acpi.c b/drivers/usb/core/usb-acpi.c
index cab5cb7c256c..8947b203d5a4 100644
--- a/drivers/usb/core/usb-acpi.c
+++ b/drivers/usb/core/usb-acpi.c
@@ -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;
 }