drivers/usb/core/usb-acpi.c

   1 /*
   2  * USB-ACPI glue code
   3  *
   4  * Copyright 2012 Red Hat <mjg@redhat.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation, version 2.
   9  *
  10  */
  11 #include <linux/module.h>
  12 #include <linux/usb.h>
  13 #include <linux/device.h>
  14 #include <linux/errno.h>
  15 #include <linux/kernel.h>
  16 #include <linux/acpi.h>
  17 #include <linux/pci.h>
  18 #include <acpi/acpi_bus.h>
  19
  20 #include "usb.h"
  21
  22 static int usb_acpi_check_upc(struct usb_device *udev, acpi_handle handle)
  23 {
  24         acpi_status status;
  25         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
  26         union acpi_object *upc;
  27         int ret = 0;
  28
  29         status = acpi_evaluate_object(handle, "_UPC", NULL, &buffer);
  30
  31         if (ACPI_FAILURE(status))
  32                 return -ENODEV;
  33
  34         upc = buffer.pointer;
  35
  36         if (!upc || (upc->type != ACPI_TYPE_PACKAGE)
  37                 || upc->package.count != 4) {
  38                 ret = -EINVAL;
  39                 goto out;
  40         }
  41
  42         if (upc->package.elements[0].integer.value)
  43                 udev->removable = USB_DEVICE_REMOVABLE;
  44         else
  45                 udev->removable = USB_DEVICE_FIXED;
  46
  47 out:
  48         kfree(upc);
  49         return ret;
  50 }
  51
  52 static int usb_acpi_check_pld(struct usb_device *udev, acpi_handle handle)
  53 {
  54         acpi_status status;
  55         struct acpi_pld pld;
  56
  57         status = acpi_get_physical_device_location(handle, &pld);
  58
  59         if (ACPI_FAILURE(status))
  60                 return -ENODEV;
  61
  62         if (pld.user_visible)
  63                 udev->removable = USB_DEVICE_REMOVABLE;
  64         else
  65                 udev->removable = USB_DEVICE_FIXED;
  66
  67         return 0;
  68 }
  69
  70 static int usb_acpi_find_device(struct device *dev, acpi_handle *handle)
  71 {
  72         struct usb_device *udev;
  73         acpi_handle *parent_handle;
  74         int port_num;
  75
  76         /*
  77          * In the ACPI DSDT table, only usb root hub and usb ports are
  78          * acpi device nodes. The hierarchy like following.
  79          * Device (EHC1)
  80          *      Device (HUBN)
  81          *              Device (PR01)
  82          *                      Device (PR11)
  83          *                      Device (PR12)
  84          *                      Device (PR13)
  85          *                      ...
  86          * So all binding process is divided into two parts. binding
  87          * root hub and usb ports.
  88          */
  89         if (is_usb_device(dev)) {
  90                 udev = to_usb_device(dev);
  91                 if (udev->parent)
  92                         return -ENODEV;
  93                 /* root hub's parent is the usb hcd. */
  94                 parent_handle = DEVICE_ACPI_HANDLE(dev->parent);
  95                 *handle = acpi_get_child(parent_handle, udev->portnum);
  96                 if (!*handle)
  97                         return -ENODEV;
  98                 return 0;
  99         } else if (is_usb_port(dev)) {
 100                 sscanf(dev_name(dev), "port%d", &port_num);
 101                 /* Get the struct usb_device point of port's hub */
 102                 udev = to_usb_device(dev->parent->parent);
 103
 104                 /*
 105                  * The root hub ports' parent is the root hub. The non-root-hub
 106                  * ports' parent is the parent hub port which the hub is
 107                  * connected to.
 108                  */
 109                 if (!udev->parent) {
 110                         *handle = acpi_get_child(DEVICE_ACPI_HANDLE(&udev->dev),
 111                                 port_num);
 112                         if (!*handle)
 113                                 return -ENODEV;
 114                 } else {
 115                         parent_handle =
 116                                 usb_get_hub_port_acpi_handle(udev->parent,
 117                                 udev->portnum);
 118                         if (!parent_handle)
 119                                 return -ENODEV;
 120
 121                         *handle = acpi_get_child(parent_handle, port_num);
 122                         if (!*handle)
 123                                 return -ENODEV;
 124                 }
 125         } else
 126                 return -ENODEV;
 127
 128         /*
 129          * PLD will tell us whether a port is removable to the user or
 130          * not. If we don't get an answer from PLD (it's not present
 131          * or it's malformed) then try to infer it from UPC. If a
 132          * device isn't connectable then it's probably not removable.
 133          */
 134         if (usb_acpi_check_pld(udev, *handle) != 0)
 135                 usb_acpi_check_upc(udev, *handle);
 136
 137         return 0;
 138 }
 139
 140 static struct acpi_bus_type usb_acpi_bus = {
 141         .bus = &usb_bus_type,
 142         .find_bridge = usb_acpi_find_device,
 143         .find_device = usb_acpi_find_device,
 144 };
 145
 146 int usb_acpi_register(void)
 147 {
 148         return register_acpi_bus_type(&usb_acpi_bus);
 149 }
 150
 151 void usb_acpi_unregister(void)
 152 {
 153         unregister_acpi_bus_type(&usb_acpi_bus);
 154 }