bitkeeper revision 1.1159.212.47 (41f97f66xOoJsNNqdPQ2dvZmBkFoHw)
authormwilli2@equilibrium.research <mwilli2@equilibrium.research>
Thu, 27 Jan 2005 23:55:18 +0000 (23:55 +0000)
committermwilli2@equilibrium.research <mwilli2@equilibrium.research>
Thu, 27 Jan 2005 23:55:18 +0000 (23:55 +0000)
Import hcd.c from vanilla Linux.  Required a couple of ifdefs to
make 2.4 xenU domains compile with USB support.

Signed-off-by: mark.williamson@cl.cam.ac.uk
.rootkeys
linux-2.4.29-xen-sparse/drivers/usb/hcd.c [new file with mode: 0644]

index 33c3a73f1e6d1a14c350942510eccfac86864bce..092d205364de93e23a2a3ddcf7dea5332960ff96 100644 (file)
--- a/.rootkeys
+++ b/.rootkeys
@@ -90,6 +90,7 @@
 3f108aeaLcGDgQdFAANLTUEid0a05w linux-2.4.29-xen-sparse/drivers/char/mem.c
 3e5a4e66rw65CxyolW9PKz4GG42RcA linux-2.4.29-xen-sparse/drivers/char/tty_io.c
 40c9c0c1pPwYE3-4i-oI3ubUu7UgvQ linux-2.4.29-xen-sparse/drivers/scsi/aic7xxx/Makefile
+41f97f64nW0wmgLxhwzPTzkF4E5ERA linux-2.4.29-xen-sparse/drivers/usb/hcd.c
 3e5a4e669uzIE54VwucPYtGwXLAbzA linux-2.4.29-xen-sparse/fs/exec.c
 3e5a4e66wbeCpsJgVf_U8Jde-CNcsA linux-2.4.29-xen-sparse/include/asm-xen/bugs.h
 3e5a4e66HdSkvIV6SJ1evG_xmTmXHA linux-2.4.29-xen-sparse/include/asm-xen/desc.h
diff --git a/linux-2.4.29-xen-sparse/drivers/usb/hcd.c b/linux-2.4.29-xen-sparse/drivers/usb/hcd.c
new file mode 100644 (file)
index 0000000..bc184e8
--- /dev/null
@@ -0,0 +1,1511 @@
+/*
+ * Copyright (c) 2001-2002 by David Brownell
+ * 
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/ioport.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/smp_lock.h>
+#include <linux/errno.h>
+#include <linux/kmod.h>
+#include <linux/init.h>
+#include <linux/timer.h>
+#include <linux/list.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/uts.h>                 /* for UTS_SYSNAME */
+
+
+#ifdef CONFIG_USB_DEBUG
+       #define DEBUG
+#else
+       #undef DEBUG
+#endif
+
+#include <linux/usb.h>
+#include "hcd.h"
+
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/system.h>
+#include <asm/unaligned.h>
+
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * USB Host Controller Driver framework
+ *
+ * Plugs into usbcore (usb_bus) and lets HCDs share code, minimizing
+ * HCD-specific behaviors/bugs.  Think of it as the "upper level" of
+ * some drivers, where the "lower level" is hardware-specific.
+ *
+ * This does error checks, tracks devices and urbs, and delegates to a
+ * "hc_driver" only for code (and data) that really needs to know about
+ * hardware differences.  That includes root hub registers, i/o queues,
+ * and so on ... but as little else as possible.
+ *
+ * Shared code includes most of the "root hub" code (these are emulated,
+ * though each HC's hardware works differently) and PCI glue, plus request
+ * tracking overhead.  The HCD code should only block on spinlocks or on
+ * hardware handshaking; blocking on software events (such as other kernel
+ * threads releasing resources, or completing actions) is all generic.
+ *
+ * Happens the USB 2.0 spec says this would be invisible inside the "USBD",
+ * and includes mostly a "HCDI" (HCD Interface) along with some APIs used
+ * only by the hub driver ... and that neither should be seen or used by
+ * usb client device drivers.
+ *
+ * Contributors of ideas or unattributed patches include: David Brownell,
+ * Roman Weissgaerber, Rory Bolt, ...
+ *
+ * HISTORY:
+ * 2002-sept   Merge some 2.5 updates so we can share hardware level HCD
+ *     code between the 2.4.20+ and 2.5 trees.
+ * 2002-feb    merge to 2.4.19
+ * 2001-12-12  Initial patch version for Linux 2.5.1 kernel.
+ */
+
+/*-------------------------------------------------------------------------*/
+
+/* host controllers we manage */
+static LIST_HEAD (hcd_list);
+
+/* used when updating list of hcds */
+static DECLARE_MUTEX (hcd_list_lock);
+
+/* used when updating hcd data */
+static spinlock_t hcd_data_lock = SPIN_LOCK_UNLOCKED;
+
+static struct usb_operations hcd_operations;
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Sharable chunks of root hub code.
+ */
+
+/*-------------------------------------------------------------------------*/
+
+#define KERNEL_REL     ((LINUX_VERSION_CODE >> 16) & 0x0ff)
+#define KERNEL_VER     ((LINUX_VERSION_CODE >> 8) & 0x0ff)
+
+/* usb 2.0 root hub device descriptor */
+static const u8 usb2_rh_dev_descriptor [18] = {
+       0x12,       /*  __u8  bLength; */
+       0x01,       /*  __u8  bDescriptorType; Device */
+       0x00, 0x02, /*  __u16 bcdUSB; v2.0 */
+
+       0x09,       /*  __u8  bDeviceClass; HUB_CLASSCODE */
+       0x00,       /*  __u8  bDeviceSubClass; */
+       0x01,       /*  __u8  bDeviceProtocol; [ usb 2.0 single TT ]*/
+       0x08,       /*  __u8  bMaxPacketSize0; 8 Bytes */
+
+       0x00, 0x00, /*  __u16 idVendor; */
+       0x00, 0x00, /*  __u16 idProduct; */
+       KERNEL_VER, KERNEL_REL, /*  __u16 bcdDevice */
+
+       0x03,       /*  __u8  iManufacturer; */
+       0x02,       /*  __u8  iProduct; */
+       0x01,       /*  __u8  iSerialNumber; */
+       0x01        /*  __u8  bNumConfigurations; */
+};
+
+/* no usb 2.0 root hub "device qualifier" descriptor: one speed only */
+
+/* usb 1.1 root hub device descriptor */
+static const u8 usb11_rh_dev_descriptor [18] = {
+       0x12,       /*  __u8  bLength; */
+       0x01,       /*  __u8  bDescriptorType; Device */
+       0x10, 0x01, /*  __u16 bcdUSB; v1.1 */
+
+       0x09,       /*  __u8  bDeviceClass; HUB_CLASSCODE */
+       0x00,       /*  __u8  bDeviceSubClass; */
+       0x00,       /*  __u8  bDeviceProtocol; [ low/full speeds only ] */
+       0x08,       /*  __u8  bMaxPacketSize0; 8 Bytes */
+
+       0x00, 0x00, /*  __u16 idVendor; */
+       0x00, 0x00, /*  __u16 idProduct; */
+       KERNEL_VER, KERNEL_REL, /*  __u16 bcdDevice */
+
+       0x03,       /*  __u8  iManufacturer; */
+       0x02,       /*  __u8  iProduct; */
+       0x01,       /*  __u8  iSerialNumber; */
+       0x01        /*  __u8  bNumConfigurations; */
+};
+
+
+/*-------------------------------------------------------------------------*/
+
+/* Configuration descriptors for our root hubs */
+
+static const u8 fs_rh_config_descriptor [] = {
+
+       /* one configuration */
+       0x09,       /*  __u8  bLength; */
+       0x02,       /*  __u8  bDescriptorType; Configuration */
+       0x19, 0x00, /*  __u16 wTotalLength; */
+       0x01,       /*  __u8  bNumInterfaces; (1) */
+       0x01,       /*  __u8  bConfigurationValue; */
+       0x00,       /*  __u8  iConfiguration; */
+       0x40,       /*  __u8  bmAttributes; 
+                                Bit 7: Bus-powered,
+                                    6: Self-powered,
+                                    5 Remote-wakwup,
+                                    4..0: resvd */
+       0x00,       /*  __u8  MaxPower; */
+      
+       /* USB 1.1:
+        * USB 2.0, single TT organization (mandatory):
+        *      one interface, protocol 0
+        *
+        * USB 2.0, multiple TT organization (optional):
+        *      two interfaces, protocols 1 (like single TT)
+        *      and 2 (multiple TT mode) ... config is
+        *      sometimes settable
+        *      NOT IMPLEMENTED
+        */
+
+       /* one interface */
+       0x09,       /*  __u8  if_bLength; */
+       0x04,       /*  __u8  if_bDescriptorType; Interface */
+       0x00,       /*  __u8  if_bInterfaceNumber; */
+       0x00,       /*  __u8  if_bAlternateSetting; */
+       0x01,       /*  __u8  if_bNumEndpoints; */
+       0x09,       /*  __u8  if_bInterfaceClass; HUB_CLASSCODE */
+       0x00,       /*  __u8  if_bInterfaceSubClass; */
+       0x00,       /*  __u8  if_bInterfaceProtocol; [usb1.1 or single tt] */
+       0x00,       /*  __u8  if_iInterface; */
+     
+       /* one endpoint (status change endpoint) */
+       0x07,       /*  __u8  ep_bLength; */
+       0x05,       /*  __u8  ep_bDescriptorType; Endpoint */
+       0x81,       /*  __u8  ep_bEndpointAddress; IN Endpoint 1 */
+       0x03,       /*  __u8  ep_bmAttributes; Interrupt */
+       0x02, 0x00, /*  __u16 ep_wMaxPacketSize; 1 + (MAX_ROOT_PORTS / 8) */
+       0xff        /*  __u8  ep_bInterval; (255ms -- usb 2.0 spec) */
+};
+
+static const u8 hs_rh_config_descriptor [] = {
+
+       /* one configuration */
+       0x09,       /*  __u8  bLength; */
+       0x02,       /*  __u8  bDescriptorType; Configuration */
+       0x19, 0x00, /*  __u16 wTotalLength; */
+       0x01,       /*  __u8  bNumInterfaces; (1) */
+       0x01,       /*  __u8  bConfigurationValue; */
+       0x00,       /*  __u8  iConfiguration; */
+       0x40,       /*  __u8  bmAttributes; 
+                                Bit 7: Bus-powered,
+                                    6: Self-powered,
+                                    5 Remote-wakwup,
+                                    4..0: resvd */
+       0x00,       /*  __u8  MaxPower; */
+      
+       /* USB 1.1:
+        * USB 2.0, single TT organization (mandatory):
+        *      one interface, protocol 0
+        *
+        * USB 2.0, multiple TT organization (optional):
+        *      two interfaces, protocols 1 (like single TT)
+        *      and 2 (multiple TT mode) ... config is
+        *      sometimes settable
+        *      NOT IMPLEMENTED
+        */
+
+       /* one interface */
+       0x09,       /*  __u8  if_bLength; */
+       0x04,       /*  __u8  if_bDescriptorType; Interface */
+       0x00,       /*  __u8  if_bInterfaceNumber; */
+       0x00,       /*  __u8  if_bAlternateSetting; */
+       0x01,       /*  __u8  if_bNumEndpoints; */
+       0x09,       /*  __u8  if_bInterfaceClass; HUB_CLASSCODE */
+       0x00,       /*  __u8  if_bInterfaceSubClass; */
+       0x00,       /*  __u8  if_bInterfaceProtocol; [usb1.1 or single tt] */
+       0x00,       /*  __u8  if_iInterface; */
+     
+       /* one endpoint (status change endpoint) */
+       0x07,       /*  __u8  ep_bLength; */
+       0x05,       /*  __u8  ep_bDescriptorType; Endpoint */
+       0x81,       /*  __u8  ep_bEndpointAddress; IN Endpoint 1 */
+       0x03,       /*  __u8  ep_bmAttributes; Interrupt */
+       0x02, 0x00, /*  __u16 ep_wMaxPacketSize; 1 + (MAX_ROOT_PORTS / 8) */
+       0x0c        /*  __u8  ep_bInterval; (256ms -- usb 2.0 spec) */
+};
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * helper routine for returning string descriptors in UTF-16LE
+ * input can actually be ISO-8859-1; ASCII is its 7-bit subset
+ */
+static int ascii2utf (char *s, u8 *utf, int utfmax)
+{
+       int retval;
+
+       for (retval = 0; *s && utfmax > 1; utfmax -= 2, retval += 2) {
+               *utf++ = *s++;
+               *utf++ = 0;
+       }
+       return retval;
+}
+
+/*
+ * rh_string - provides manufacturer, product and serial strings for root hub
+ * @id: the string ID number (1: serial number, 2: product, 3: vendor)
+ * @pci_desc: PCI device descriptor for the relevant HC
+ * @type: string describing our driver 
+ * @data: return packet in UTF-16 LE
+ * @len: length of the return packet
+ *
+ * Produces either a manufacturer, product or serial number string for the
+ * virtual root hub device.
+ */
+static int rh_string (
+       int             id,
+       struct usb_hcd  *hcd,
+       u8              *data,
+       int             len
+) {
+       char buf [100];
+
+       // language ids
+       if (id == 0) {
+               *data++ = 4; *data++ = 3;       /* 4 bytes string data */
+               *data++ = 0; *data++ = 0;       /* some language id */
+               return 4;
+
+       // serial number
+       } else if (id == 1) {
+               strcpy (buf, hcd->bus->bus_name);
+
+       // product description
+       } else if (id == 2) {
+                strcpy (buf, hcd->product_desc);
+
+       // id 3 == vendor description
+       } else if (id == 3) {
+                sprintf (buf, "%s %s %s", UTS_SYSNAME, UTS_RELEASE,
+                       hcd->description);
+
+       // unsupported IDs --> "protocol stall"
+       } else
+           return 0;
+
+       data [0] = 2 * (strlen (buf) + 1);
+       data [1] = 3;   /* type == string */
+       return 2 + ascii2utf (buf, data + 2, len - 2);
+}
+
+
+/* Root hub control transfers execute synchronously */
+static int rh_call_control (struct usb_hcd *hcd, struct urb *urb)
+{
+       struct usb_ctrlrequest *cmd = (struct usb_ctrlrequest *) urb->setup_packet;
+       u16             typeReq, wValue, wIndex, wLength;
+       const u8        *bufp = 0;
+       u8              *ubuf = urb->transfer_buffer;
+       int             len = 0;
+
+       typeReq  = (cmd->bRequestType << 8) | cmd->bRequest;
+       wValue   = le16_to_cpu (cmd->wValue);
+       wIndex   = le16_to_cpu (cmd->wIndex);
+       wLength  = le16_to_cpu (cmd->wLength);
+
+       if (wLength > urb->transfer_buffer_length)
+               goto error;
+
+       /* set up for success */
+       urb->status = 0;
+       urb->actual_length = wLength;
+       switch (typeReq) {
+
+       /* DEVICE REQUESTS */
+
+       case DeviceRequest | USB_REQ_GET_STATUS:
+               // DEVICE_REMOTE_WAKEUP
+               ubuf [0] = 1; // selfpowered
+               ubuf [1] = 0;
+                       /* FALLTHROUGH */
+       case DeviceOutRequest | USB_REQ_CLEAR_FEATURE:
+       case DeviceOutRequest | USB_REQ_SET_FEATURE:
+               dbg ("no device features yet yet");
+               break;
+       case DeviceRequest | USB_REQ_GET_CONFIGURATION:
+               ubuf [0] = 1;
+                       /* FALLTHROUGH */
+       case DeviceOutRequest | USB_REQ_SET_CONFIGURATION:
+               break;
+       case DeviceRequest | USB_REQ_GET_DESCRIPTOR:
+               switch (wValue & 0xff00) {
+               case USB_DT_DEVICE << 8:
+                       if (hcd->driver->flags & HCD_USB2)
+                               bufp = usb2_rh_dev_descriptor;
+                       else if (hcd->driver->flags & HCD_USB11)
+                               bufp = usb11_rh_dev_descriptor;
+                       else
+                               goto error;
+                       len = 18;
+                       break;
+               case USB_DT_CONFIG << 8:
+                       if (hcd->driver->flags & HCD_USB2) {
+                               bufp = hs_rh_config_descriptor;
+                               len = sizeof hs_rh_config_descriptor;
+                       } else {
+                               bufp = fs_rh_config_descriptor;
+                               len = sizeof fs_rh_config_descriptor;
+                       }
+                       break;
+               case USB_DT_STRING << 8:
+                       urb->actual_length = rh_string (
+                               wValue & 0xff, hcd,
+                               ubuf, wLength);
+                       break;
+               default:
+                       goto error;
+               }
+               break;
+       case DeviceRequest | USB_REQ_GET_INTERFACE:
+               ubuf [0] = 0;
+                       /* FALLTHROUGH */
+       case DeviceOutRequest | USB_REQ_SET_INTERFACE:
+               break;
+       case DeviceOutRequest | USB_REQ_SET_ADDRESS:
+               // wValue == urb->dev->devaddr
+               dbg ("%s root hub device address %d",
+                       hcd->bus->bus_name, wValue);
+               break;
+
+       /* INTERFACE REQUESTS (no defined feature/status flags) */
+
+       /* ENDPOINT REQUESTS */
+
+       case EndpointRequest | USB_REQ_GET_STATUS:
+               // ENDPOINT_HALT flag
+               ubuf [0] = 0;
+               ubuf [1] = 0;
+                       /* FALLTHROUGH */
+       case EndpointOutRequest | USB_REQ_CLEAR_FEATURE:
+       case EndpointOutRequest | USB_REQ_SET_FEATURE:
+               dbg ("no endpoint features yet");
+               break;
+
+       /* CLASS REQUESTS (and errors) */
+
+       default:
+               /* non-generic request */
+               urb->status = hcd->driver->hub_control (hcd,
+                       typeReq, wValue, wIndex,
+                       ubuf, wLength);
+               break;
+error:
+               /* "protocol stall" on error */
+               urb->status = -EPIPE;
+               dbg ("unsupported hub control message (maxchild %d)",
+                               urb->dev->maxchild);
+       }
+       if (urb->status) {
+               urb->actual_length = 0;
+               dbg ("CTRL: TypeReq=0x%x val=0x%x idx=0x%x len=%d ==> %d",
+                       typeReq, wValue, wIndex, wLength, urb->status);
+       }
+       if (bufp) {
+               if (urb->transfer_buffer_length < len)
+                       len = urb->transfer_buffer_length;
+               urb->actual_length = len;
+               // always USB_DIR_IN, toward host
+               memcpy (ubuf, bufp, len);
+       }
+
+       /* any errors get returned through the urb completion */
+       usb_hcd_giveback_urb (hcd, urb, 0);
+       return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Root Hub interrupt transfers are synthesized with a timer.
+ * Completions are called in_interrupt() but not in_irq().
+ */
+
+static void rh_report_status (unsigned long ptr);
+
+static int rh_status_urb (struct usb_hcd *hcd, struct urb *urb) 
+{
+       int     len = 1 + (urb->dev->maxchild / 8);
+
+       /* rh_timer protected by hcd_data_lock */
+       if (timer_pending (&hcd->rh_timer)
+                       || urb->status != -EINPROGRESS
+                       || !HCD_IS_RUNNING (hcd->state)
+                       || urb->transfer_buffer_length < len) {
+               dbg ("not queuing status urb, stat %d", urb->status);
+               return -EINVAL;
+       }
+
+       urb->hcpriv = hcd;      /* nonzero to indicate it's queued */
+       init_timer (&hcd->rh_timer);
+       hcd->rh_timer.function = rh_report_status;
+       hcd->rh_timer.data = (unsigned long) urb;
+       /* USB 2.0 spec says 256msec; this is close enough */
+       hcd->rh_timer.expires = jiffies + HZ/4;
+       add_timer (&hcd->rh_timer);
+       return 0;
+}
+
+/* timer callback */
+
+static void rh_report_status (unsigned long ptr)
+{
+       struct urb      *urb;
+       struct usb_hcd  *hcd;
+       int             length;
+       unsigned long   flags;
+
+       urb = (struct urb *) ptr;
+       spin_lock_irqsave (&urb->lock, flags);
+       if (!urb->dev) {
+               spin_unlock_irqrestore (&urb->lock, flags);
+               return;
+       }
+
+       hcd = urb->dev->bus->hcpriv;
+       if (urb->status == -EINPROGRESS) {
+               if (HCD_IS_RUNNING (hcd->state)) {
+                       length = hcd->driver->hub_status_data (hcd,
+                                       urb->transfer_buffer);
+                       spin_unlock_irqrestore (&urb->lock, flags);
+                       if (length > 0) {
+                               urb->actual_length = length;
+                               urb->status = 0;
+                               urb->complete (urb);
+                       }
+                       spin_lock_irqsave (&hcd_data_lock, flags);
+                       urb->status = -EINPROGRESS;
+                       if (HCD_IS_RUNNING (hcd->state)
+                                       && rh_status_urb (hcd, urb) != 0) {
+                               /* another driver snuck in? */
+                               dbg ("%s, can't resubmit roothub status urb?",
+                                       hcd->bus->bus_name);
+                               spin_unlock_irqrestore (&hcd_data_lock, flags);
+                               BUG ();
+                       }
+                       spin_unlock_irqrestore (&hcd_data_lock, flags);
+               } else
+                       spin_unlock_irqrestore (&urb->lock, flags);
+       } else {
+               /* this urb's been unlinked */
+               urb->hcpriv = 0;
+               spin_unlock_irqrestore (&urb->lock, flags);
+
+               usb_hcd_giveback_urb (hcd, urb, 0);
+       }
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int rh_urb_enqueue (struct usb_hcd *hcd, struct urb *urb)
+{
+       if (usb_pipeint (urb->pipe)) {
+               int             retval;
+               unsigned long   flags;
+
+               spin_lock_irqsave (&hcd_data_lock, flags);
+               retval = rh_status_urb (hcd, urb);
+               spin_unlock_irqrestore (&hcd_data_lock, flags);
+               return retval;
+       }
+       if (usb_pipecontrol (urb->pipe))
+               return rh_call_control (hcd, urb);
+       else
+               return -EINVAL;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void rh_status_dequeue (struct usb_hcd *hcd, struct urb *urb)
+{
+       unsigned long   flags;
+
+       spin_lock_irqsave (&hcd_data_lock, flags);
+       del_timer_sync (&hcd->rh_timer);
+       hcd->rh_timer.data = 0;
+       spin_unlock_irqrestore (&hcd_data_lock, flags);
+
+       /* we rely on RH callback code not unlinking its URB! */
+       usb_hcd_giveback_urb (hcd, urb, 0);
+}
+
+/*-------------------------------------------------------------------------*/
+
+#ifdef CONFIG_PCI
+
+/* PCI-based HCs are normal, but custom bus glue should be ok */
+
+static void hcd_irq (int irq, void *__hcd, struct pt_regs *r);
+static void hc_died (struct usb_hcd *hcd);
+
+/*-------------------------------------------------------------------------*/
+
+/* configure so an HC device and id are always provided */
+/* always called with process context; sleeping is OK */
+
+/**
+ * usb_hcd_pci_probe - initialize PCI-based HCDs
+ * @dev: USB Host Controller being probed
+ * @id: pci hotplug id connecting controller to HCD framework
+ * Context: !in_interrupt()
+ *
+ * Allocates basic PCI resources for this USB host controller, and
+ * then invokes the start() method for the HCD associated with it
+ * through the hotplug entry's driver_data.
+ *
+ * Store this function in the HCD's struct pci_driver as probe().
+ */
+int usb_hcd_pci_probe (struct pci_dev *dev, const struct pci_device_id *id)
+{
+       struct hc_driver        *driver;
+       unsigned long           resource, len;
+       void                    *base;
+       struct usb_bus          *bus;
+       struct usb_hcd          *hcd;
+       int                     retval, region;
+       char                    buf [8], *bufp = buf;
+
+       if (!id || !(driver = (struct hc_driver *) id->driver_data))
+               return -EINVAL;
+
+       if (pci_enable_device (dev) < 0)
+               return -ENODEV;
+       
+        if (!dev->irq) {
+               err ("Found HC with no IRQ.  Check BIOS/PCI %s setup!",
+                       dev->slot_name);
+               return -ENODEV;
+        }
+       
+       if (driver->flags & HCD_MEMORY) {       // EHCI, OHCI
+               region = 0;
+               resource = pci_resource_start (dev, 0);
+               len = pci_resource_len (dev, 0);
+               if (!request_mem_region (resource, len, driver->description)) {
+                       dbg ("controller already in use");
+                       return -EBUSY;
+               }
+               base = ioremap_nocache (resource, len);
+               if (base == NULL) {
+                       dbg ("error mapping memory");
+                       retval = -EFAULT;
+clean_1:
+                       release_mem_region (resource, len);
+                       err ("init %s fail, %d", dev->slot_name, retval);
+                       return retval;
+               }
+
+       } else {                                // UHCI
+               resource = len = 0;
+               for (region = 0; region < PCI_ROM_RESOURCE; region++) {
+                       if (!(pci_resource_flags (dev, region) & IORESOURCE_IO))
+                               continue;
+
+                       resource = pci_resource_start (dev, region);
+                       len = pci_resource_len (dev, region);
+                       if (request_region (resource, len,
+                                       driver->description))
+                               break;
+               }
+               if (region == PCI_ROM_RESOURCE) {
+                       dbg ("no i/o regions available");
+                       return -EBUSY;
+               }
+               base = (void *) resource;
+       }
+
+       // driver->start(), later on, will transfer device from
+       // control by SMM/BIOS to control by Linux (if needed)
+
+       pci_set_master (dev);
+       hcd = driver->hcd_alloc ();
+       if (hcd == NULL){
+               dbg ("hcd alloc fail");
+               retval = -ENOMEM;
+clean_2:
+               if (driver->flags & HCD_MEMORY) {
+                       iounmap (base);
+                       goto clean_1;
+               } else {
+                       release_region (resource, len);
+                       err ("init %s fail, %d", dev->slot_name, retval);
+                       return retval;
+               }
+       }
+       pci_set_drvdata(dev, hcd);
+       hcd->driver = driver;
+       hcd->description = driver->description;
+       hcd->pdev = dev;
+       printk (KERN_INFO "%s %s: %s\n",
+                       hcd->description,  dev->slot_name, dev->name);
+
+#ifndef __sparc__
+       sprintf (buf, "%d", dev->irq);
+#else
+       bufp = __irq_itoa(dev->irq);
+#endif
+       if (request_irq (dev->irq, hcd_irq, SA_SHIRQ, hcd->description, hcd)
+                       != 0) {
+               err ("request interrupt %s failed", bufp);
+               retval = -EBUSY;
+clean_3:
+               driver->hcd_free (hcd);
+               goto clean_2;
+       }
+       hcd->irq = dev->irq;
+
+       hcd->regs = base;
+       hcd->region = region;
+       printk (KERN_INFO "%s %s: irq %s, %s %p\n",
+               hcd->description,  dev->slot_name, bufp,
+               (driver->flags & HCD_MEMORY) ? "pci mem" : "io base",
+               base);
+
+// FIXME simpler: make "bus" be that data, not pointer to it.
+// (fixed in 2.5)
+       bus = usb_alloc_bus (&hcd_operations);
+       if (bus == NULL) {
+               dbg ("usb_alloc_bus fail");
+               retval = -ENOMEM;
+               free_irq (dev->irq, hcd);
+               goto clean_3;
+       }
+       hcd->bus = bus;
+       bus->bus_name = dev->slot_name;
+       hcd->product_desc = dev->name;
+       bus->hcpriv = (void *) hcd;
+
+       INIT_LIST_HEAD (&hcd->dev_list);
+       INIT_LIST_HEAD (&hcd->hcd_list);
+
+       down (&hcd_list_lock);
+       list_add (&hcd->hcd_list, &hcd_list);
+       up (&hcd_list_lock);
+
+       usb_register_bus (bus);
+
+       if ((retval = driver->start (hcd)) < 0)
+               usb_hcd_pci_remove (dev);
+
+       return retval;
+} 
+EXPORT_SYMBOL (usb_hcd_pci_probe);
+
+
+/* may be called without controller electrically present */
+/* may be called with controller, bus, and devices active */
+
+/**
+ * usb_hcd_pci_remove - shutdown processing for PCI-based HCDs
+ * @dev: USB Host Controller being removed
+ * Context: !in_interrupt()
+ *
+ * Reverses the effect of usb_hcd_pci_probe(), first invoking
+ * the HCD's stop() method.  It is always called from a thread
+ * context, normally "rmmod", "apmd", or something similar.
+ *
+ * Store this function in the HCD's struct pci_driver as remove().
+ */
+void usb_hcd_pci_remove (struct pci_dev *dev)
+{
+       struct usb_hcd          *hcd;
+       struct usb_device       *hub;
+
+       hcd = pci_get_drvdata(dev);
+       if (!hcd)
+               return;
+       printk (KERN_INFO "%s %s: remove state %x\n",
+               hcd->description,  dev->slot_name, hcd->state);
+
+       if (in_interrupt ()) BUG ();
+
+       hub = hcd->bus->root_hub;
+       hcd->state = USB_STATE_QUIESCING;
+
+       dbg ("%s: roothub graceful disconnect", hcd->bus->bus_name);
+       usb_disconnect (&hub);
+       // usb_disconnect (&hcd->bus->root_hub);
+
+       hcd->driver->stop (hcd);
+       hcd->state = USB_STATE_HALT;
+
+       free_irq (hcd->irq, hcd);
+       if (hcd->driver->flags & HCD_MEMORY) {
+               iounmap (hcd->regs);
+               release_mem_region (pci_resource_start (dev, 0),
+                       pci_resource_len (dev, 0));
+       } else {
+               release_region (pci_resource_start (dev, hcd->region),
+                       pci_resource_len (dev, hcd->region));
+       }
+
+       down (&hcd_list_lock);
+       list_del (&hcd->hcd_list);
+       up (&hcd_list_lock);
+
+       usb_deregister_bus (hcd->bus);
+       usb_free_bus (hcd->bus);
+       hcd->bus = NULL;
+
+       hcd->driver->hcd_free (hcd);
+}
+EXPORT_SYMBOL (usb_hcd_pci_remove);
+
+
+#ifdef CONFIG_PM
+
+/*
+ * Some "sleep" power levels imply updating struct usb_driver
+ * to include a callback asking hcds to do their bit by checking
+ * if all the drivers can suspend.  Gets involved with remote wakeup.
+ *
+ * If there are pending urbs, then HCs will need to access memory,
+ * causing extra power drain.  New sleep()/wakeup() PM calls might
+ * be needed, beyond PCI suspend()/resume().  The root hub timer
+ * still be accessing memory though ...
+ *
+ * FIXME:  USB should have some power budgeting support working with
+ * all kinds of hubs.
+ *
+ * FIXME:  This assumes only D0->D3 suspend and D3->D0 resume.
+ * D1 and D2 states should do something, yes?
+ *
+ * FIXME:  Should provide generic enable_wake(), calling pci_enable_wake()
+ * for all supported states, so that USB remote wakeup can work for any
+ * devices that support it (and are connected via powered hubs).
+ *
+ * FIXME:  resume doesn't seem to work right any more...
+ */
+
+
+// 2.4 kernels have issued concurrent resumes (w/APM)
+// we defend against that error; PCI doesn't yet.
+
+/**
+ * usb_hcd_pci_suspend - power management suspend of a PCI-based HCD
+ * @dev: USB Host Controller being suspended
+ *
+ * Store this function in the HCD's struct pci_driver as suspend().
+ */
+int usb_hcd_pci_suspend (struct pci_dev *dev, u32 state)
+{
+       struct usb_hcd          *hcd;
+       int                     retval;
+
+       hcd = pci_get_drvdata(dev);
+       printk (KERN_INFO "%s %s: suspend to state %d\n",
+               hcd->description,  dev->slot_name, state);
+
+       pci_save_state (dev, hcd->pci_state);
+
+       // FIXME for all connected devices, leaf-to-root:
+       // driver->suspend()
+       // proposed "new 2.5 driver model" will automate that
+
+       /* driver may want to disable DMA etc */
+       retval = hcd->driver->suspend (hcd, state);
+       hcd->state = USB_STATE_SUSPENDED;
+
+       pci_set_power_state (dev, state);
+       return retval;
+}
+EXPORT_SYMBOL (usb_hcd_pci_suspend);
+
+/**
+ * usb_hcd_pci_resume - power management resume of a PCI-based HCD
+ * @dev: USB Host Controller being resumed
+ *
+ * Store this function in the HCD's struct pci_driver as resume().
+ */
+int usb_hcd_pci_resume (struct pci_dev *dev)
+{
+       struct usb_hcd          *hcd;
+       int                     retval;
+
+       hcd = pci_get_drvdata(dev);
+       printk (KERN_INFO "%s %s: resume\n",
+               hcd->description,  dev->slot_name);
+
+       /* guard against multiple resumes (APM bug?) */
+       atomic_inc (&hcd->resume_count);
+       if (atomic_read (&hcd->resume_count) != 1) {
+               err ("concurrent PCI resumes for %s", hcd->bus->bus_name);
+               retval = 0;
+               goto done;
+       }
+
+       retval = -EBUSY;
+       if (hcd->state != USB_STATE_SUSPENDED) {
+               dbg ("can't resume, not suspended!");
+               goto done;
+       }
+       hcd->state = USB_STATE_RESUMING;
+
+       pci_set_power_state (dev, 0);
+       pci_restore_state (dev, hcd->pci_state);
+
+       retval = hcd->driver->resume (hcd);
+       if (!HCD_IS_RUNNING (hcd->state)) {
+               dbg ("resume %s failure, retval %d",
+                       hcd->bus->bus_name, retval);
+               hc_died (hcd);
+// FIXME:  recover, reset etc.
+       } else {
+               // FIXME for all connected devices, root-to-leaf:
+               // driver->resume ();
+               // proposed "new 2.5 driver model" will automate that
+       }
+
+done:
+       atomic_dec (&hcd->resume_count);
+       return retval;
+}
+EXPORT_SYMBOL (usb_hcd_pci_resume);
+
+#endif /* CONFIG_PM */
+
+#endif
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Generic HC operations.
+ */
+
+/*-------------------------------------------------------------------------*/
+
+/* called from khubd, or root hub init threads for hcd-private init */
+static int hcd_alloc_dev (struct usb_device *udev)
+{
+       struct hcd_dev          *dev;
+       struct usb_hcd          *hcd;
+       unsigned long           flags;
+
+       if (!udev || udev->hcpriv)
+               return -EINVAL;
+       if (!udev->bus || !udev->bus->hcpriv)
+               return -ENODEV;
+       hcd = udev->bus->hcpriv;
+       if (hcd->state == USB_STATE_QUIESCING)
+               return -ENOLINK;
+
+       dev = (struct hcd_dev *) kmalloc (sizeof *dev, GFP_KERNEL);
+       if (dev == NULL)
+               return -ENOMEM;
+       memset (dev, 0, sizeof *dev);
+
+       INIT_LIST_HEAD (&dev->dev_list);
+       INIT_LIST_HEAD (&dev->urb_list);
+
+       spin_lock_irqsave (&hcd_data_lock, flags);
+       list_add (&dev->dev_list, &hcd->dev_list);
+       // refcount is implicit
+       udev->hcpriv = dev;
+       spin_unlock_irqrestore (&hcd_data_lock, flags);
+
+       return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void hcd_panic (void *_hcd)
+{
+       struct usb_hcd *hcd = _hcd;
+       hcd->driver->stop (hcd);
+}
+
+static void hc_died (struct usb_hcd *hcd)
+{
+       struct list_head        *devlist, *urblist;
+       struct hcd_dev          *dev;
+       struct urb              *urb;
+       unsigned long           flags;
+       
+       /* flag every pending urb as done */
+       spin_lock_irqsave (&hcd_data_lock, flags);
+       list_for_each (devlist, &hcd->dev_list) {
+               dev = list_entry (devlist, struct hcd_dev, dev_list);
+               list_for_each (urblist, &dev->urb_list) {
+                       urb = list_entry (urblist, struct urb, urb_list);
+                       dbg ("shutdown %s urb %p pipe %x, current status %d",
+                               hcd->bus->bus_name,
+                               urb, urb->pipe, urb->status);
+                       if (urb->status == -EINPROGRESS)
+                               urb->status = -ESHUTDOWN;
+               }
+       }
+       urb = (struct urb *) hcd->rh_timer.data;
+       if (urb)
+               urb->status = -ESHUTDOWN;
+       spin_unlock_irqrestore (&hcd_data_lock, flags);
+
+       if (urb)
+               rh_status_dequeue (hcd, urb);
+
+       /* hcd->stop() needs a task context */
+       INIT_TQUEUE (&hcd->work, hcd_panic, hcd);
+       (void) schedule_task (&hcd->work);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void urb_unlink (struct urb *urb)
+{
+       unsigned long           flags;
+       struct usb_device       *dev;
+
+       /* Release any periodic transfer bandwidth */
+       if (urb->bandwidth)
+               usb_release_bandwidth (urb->dev, urb,
+                       usb_pipeisoc (urb->pipe));
+
+       /* clear all state linking urb to this dev (and hcd) */
+
+       spin_lock_irqsave (&hcd_data_lock, flags);
+       list_del_init (&urb->urb_list);
+       dev = urb->dev;
+       urb->dev = NULL;
+       usb_dec_dev_use (dev);
+       spin_unlock_irqrestore (&hcd_data_lock, flags);
+}
+
+
+/* may be called in any context with a valid urb->dev usecount */
+/* caller surrenders "ownership" of urb */
+
+static int hcd_submit_urb (struct urb *urb)
+{
+       int                     status;
+       struct usb_hcd          *hcd;
+       struct hcd_dev          *dev;
+       unsigned long           flags;
+       int                     pipe, temp, max;
+       int                     mem_flags;
+
+       if (!urb || urb->hcpriv || !urb->complete)
+               return -EINVAL;
+
+       urb->status = -EINPROGRESS;
+       urb->actual_length = 0;
+       urb->bandwidth = 0;
+       INIT_LIST_HEAD (&urb->urb_list);
+
+       if (!urb->dev || !urb->dev->bus || urb->dev->devnum <= 0)
+               return -ENODEV;
+       hcd = urb->dev->bus->hcpriv;
+       dev = urb->dev->hcpriv;
+       if (!hcd || !dev)
+               return -ENODEV;
+
+       /* can't submit new urbs when quiescing, halted, ... */
+       if (hcd->state == USB_STATE_QUIESCING || !HCD_IS_RUNNING (hcd->state))
+               return -ESHUTDOWN;
+       pipe = urb->pipe;
+       temp = usb_pipetype (urb->pipe);
+       if (usb_endpoint_halted (urb->dev, usb_pipeendpoint (pipe),
+                       usb_pipeout (pipe)))
+               return -EPIPE;
+
+       /* NOTE: 2.5 passes this value explicitly in submit() */
+       mem_flags = GFP_ATOMIC;
+
+       /* FIXME there should be a sharable lock protecting us against
+        * config/altsetting changes and disconnects, kicking in here.
+        */
+
+       /* Sanity check, so HCDs can rely on clean data */
+       max = usb_maxpacket (urb->dev, pipe, usb_pipeout (pipe));
+       if (max <= 0) {
+               err ("bogus endpoint (bad maxpacket)");
+               return -EINVAL;
+       }
+
+       /* "high bandwidth" mode, 1-3 packets/uframe? */
+       if (urb->dev->speed == USB_SPEED_HIGH) {
+               int     mult;
+               switch (temp) {
+               case PIPE_ISOCHRONOUS:
+               case PIPE_INTERRUPT:
+                       mult = 1 + ((max >> 11) & 0x03);
+                       max &= 0x03ff;
+                       max *= mult;
+               }
+       }
+
+       /* periodic transfers limit size per frame/uframe */
+       switch (temp) {
+       case PIPE_ISOCHRONOUS: {
+               int     n, len;
+
+               if (urb->number_of_packets <= 0)                    
+                       return -EINVAL;
+               for (n = 0; n < urb->number_of_packets; n++) {
+                       len = urb->iso_frame_desc [n].length;
+                       if (len < 0 || len > max) 
+                               return -EINVAL;
+               }
+
+               }
+               break;
+       case PIPE_INTERRUPT:
+               if (urb->transfer_buffer_length > max)
+                       return -EINVAL;
+       }
+
+       /* the I/O buffer must usually be mapped/unmapped */
+       if (urb->transfer_buffer_length < 0)
+               return -EINVAL;
+
+       if (urb->next) {
+               warn ("use explicit queuing not urb->next");
+               return -EINVAL;
+       }
+
+#ifdef DEBUG
+       /* stuff that drivers shouldn't do, but which shouldn't
+        * cause problems in HCDs if they get it wrong.
+        */
+       {
+       unsigned int    orig_flags = urb->transfer_flags;
+       unsigned int    allowed;
+
+       /* enforce simple/standard policy */
+       allowed = USB_ASYNC_UNLINK;     // affects later unlinks
+       allowed |= USB_NO_FSBR;         // only affects UHCI
+       switch (temp) {
+       case PIPE_CONTROL:
+               allowed |= USB_DISABLE_SPD;
+               break;
+       case PIPE_BULK:
+               allowed |= USB_DISABLE_SPD | USB_QUEUE_BULK
+                               | USB_ZERO_PACKET | URB_NO_INTERRUPT;
+               break;
+       case PIPE_INTERRUPT:
+               allowed |= USB_DISABLE_SPD;
+               break;
+       case PIPE_ISOCHRONOUS:
+               allowed |= USB_ISO_ASAP;
+               break;
+       }
+       urb->transfer_flags &= allowed;
+
+       /* fail if submitter gave bogus flags */
+       if (urb->transfer_flags != orig_flags) {
+               err ("BOGUS urb flags, %x --> %x",
+                       orig_flags, urb->transfer_flags);
+               return -EINVAL;
+       }
+       }
+#endif
+       /*
+        * Force periodic transfer intervals to be legal values that are
+        * a power of two (so HCDs don't need to).
+        *
+        * FIXME want bus->{intr,iso}_sched_horizon values here.  Each HC
+        * supports different values... this uses EHCI/UHCI defaults (and
+        * EHCI can use smaller non-default values).
+        */
+       switch (temp) {
+       case PIPE_ISOCHRONOUS:
+       case PIPE_INTERRUPT:
+               /* too small? */
+               if (urb->interval <= 0)
+                       return -EINVAL;
+               /* too big? */
+               switch (urb->dev->speed) {
+               case USB_SPEED_HIGH:    /* units are microframes */
+                       // NOTE usb handles 2^15
+                       if (urb->interval > (1024 * 8))
+                               urb->interval = 1024 * 8;
+                       temp = 1024 * 8;
+                       break;
+               case USB_SPEED_FULL:    /* units are frames/msec */
+               case USB_SPEED_LOW:
+                       if (temp == PIPE_INTERRUPT) {
+                               if (urb->interval > 255)
+                                       return -EINVAL;
+                               // NOTE ohci only handles up to 32
+                               temp = 128;
+                       } else {
+                               if (urb->interval > 1024)
+                                       urb->interval = 1024;
+                               // NOTE usb and ohci handle up to 2^15
+                               temp = 1024;
+                       }
+                       break;
+               default:
+                       return -EINVAL;
+               }
+               /* power of two? */
+               while (temp > urb->interval)
+                       temp >>= 1;
+               urb->interval = temp;
+       }
+
+
+       /*
+        * FIXME:  make urb timeouts be generic, keeping the HCD cores
+        * as simple as possible.
+        */
+
+       // NOTE:  a generic device/urb monitoring hook would go here.
+       // hcd_monitor_hook(MONITOR_URB_SUBMIT, urb)
+       // It would catch submission paths for all urbs.
+
+       /*
+        * Atomically queue the urb,  first to our records, then to the HCD.
+        * Access to urb->status is controlled by urb->lock ... changes on
+        * i/o completion (normal or fault) or unlinking.
+        */
+
+       // FIXME:  verify that quiescing hc works right (RH cleans up)
+
+       spin_lock_irqsave (&hcd_data_lock, flags);
+       if (HCD_IS_RUNNING (hcd->state) && hcd->state != USB_STATE_QUIESCING) {
+               usb_inc_dev_use (urb->dev);
+               list_add (&urb->urb_list, &dev->urb_list);
+               status = 0;
+       } else {
+               INIT_LIST_HEAD (&urb->urb_list);
+               status = -ESHUTDOWN;
+       }
+       spin_unlock_irqrestore (&hcd_data_lock, flags);
+       if (status)
+               return status;
+
+       // NOTE:  2.5 does this if !URB_NO_DMA_MAP transfer flag
+       
+       /* For 2.4, don't map bounce buffer if it's a root hub operation. */
+       if (urb->dev == hcd->bus->root_hub) {
+               status = rh_urb_enqueue (hcd, urb);
+       } else {
+#ifdef CONFIG_PCI
+               if (usb_pipecontrol (urb->pipe))
+                       urb->setup_dma = pci_map_single (
+                                       hcd->pdev,
+                                       urb->setup_packet,
+                                       sizeof (struct usb_ctrlrequest),
+                                       PCI_DMA_TODEVICE);
+               if (urb->transfer_buffer_length != 0)
+                       urb->transfer_dma = pci_map_single (
+                                       hcd->pdev,
+                                       urb->transfer_buffer,
+                                       urb->transfer_buffer_length,
+                                       usb_pipein (urb->pipe)
+                                           ? PCI_DMA_FROMDEVICE
+                                           : PCI_DMA_TODEVICE);
+#endif
+               status = hcd->driver->urb_enqueue (hcd, urb, mem_flags);
+       }
+       return status;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* called in any context */
+static int hcd_get_frame_number (struct usb_device *udev)
+{
+       struct usb_hcd  *hcd = (struct usb_hcd *)udev->bus->hcpriv;
+       return hcd->driver->get_frame_number (hcd);
+}
+
+/*-------------------------------------------------------------------------*/
+
+struct completion_splice {             // modified urb context:
+       /* did we complete? */
+       struct completion       done;
+
+       /* original urb data */
+       void                    (*complete)(struct urb *);
+       void                    *context;
+};
+
+static void unlink_complete (struct urb *urb)
+{
+       struct completion_splice        *splice;
+
+       splice = (struct completion_splice *) urb->context;
+
+       /* issue original completion call */
+       urb->complete = splice->complete;
+       urb->context = splice->context;
+       urb->complete (urb);
+
+       /* then let the synchronous unlink call complete */
+       complete (&splice->done);
+}
+
+/*
+ * called in any context; note ASYNC_UNLINK restrictions
+ *
+ * caller guarantees urb won't be recycled till both unlink()
+ * and the urb's completion function return
+ */
+static int hcd_unlink_urb (struct urb *urb)
+{
+       struct hcd_dev                  *dev;
+       struct usb_hcd                  *hcd = 0;
+       unsigned long                   flags;
+       struct completion_splice        splice;
+       int                             retval;
+
+       if (!urb)
+               return -EINVAL;
+
+       /*
+        * we contend for urb->status with the hcd core,
+        * which changes it while returning the urb.
+        *
+        * Caller guaranteed that the urb pointer hasn't been freed, and
+        * that it was submitted.  But as a rule it can't know whether or
+        * not it's already been unlinked ... so we respect the reversed
+        * lock sequence needed for the usb_hcd_giveback_urb() code paths
+        * (urb lock, then hcd_data_lock) in case some other CPU is now
+        * unlinking it.
+        */
+       spin_lock_irqsave (&urb->lock, flags);
+       spin_lock (&hcd_data_lock);
+       if (!urb->hcpriv || urb->transfer_flags & USB_TIMEOUT_KILLED) {
+               retval = -EINVAL;
+               goto done;
+       }
+
+       if (!urb->dev || !urb->dev->bus) {
+               retval = -ENODEV;
+               goto done;
+       }
+
+       /* giveback clears dev; non-null means it's linked at this level */
+       dev = urb->dev->hcpriv;
+       hcd = urb->dev->bus->hcpriv;
+       if (!dev || !hcd) {
+               retval = -ENODEV;
+               goto done;
+       }
+
+       /* Any status except -EINPROGRESS means the HCD has already started
+        * to return this URB to the driver.  In that case, there's no
+        * more work for us to do.
+        *
+        * There's much magic because of "automagic resubmit" of interrupt
+        * transfers, stopped only by explicit unlinking.  We won't issue
+        * an "it's unlinked" callback more than once, but device drivers
+        * can need to retry (SMP, -EAGAIN) an unlink request as well as
+        * fake out the "not yet completed" state (set -EINPROGRESS) if
+        * unlinking from complete().  Automagic eventually vanishes.
+        *
+        * FIXME use an URB_UNLINKED flag to match URB_TIMEOUT_KILLED
+        */
+       if (urb->status != -EINPROGRESS) {
+               if (usb_pipetype (urb->pipe) == PIPE_INTERRUPT)
+                       retval = -EAGAIN;
+               else
+                       retval = -EBUSY;
+               goto done;
+       }
+
+       /* maybe set up to block on completion notification */
+       if ((urb->transfer_flags & USB_TIMEOUT_KILLED))
+               urb->status = -ETIMEDOUT;
+       else if (!(urb->transfer_flags & USB_ASYNC_UNLINK)) {
+               if (in_interrupt ()) {
+                       dbg ("non-async unlink in_interrupt");
+                       retval = -EWOULDBLOCK;
+                       goto done;
+               }
+               /* synchronous unlink: block till we see the completion */
+               init_completion (&splice.done);
+               splice.complete = urb->complete;
+               splice.context = urb->context;
+               urb->complete = unlink_complete;
+               urb->context = &splice;
+               urb->status = -ENOENT;
+       } else {
+               /* asynchronous unlink */
+               urb->status = -ECONNRESET;
+       }
+       spin_unlock (&hcd_data_lock);
+       spin_unlock_irqrestore (&urb->lock, flags);
+
+       if (urb == (struct urb *) hcd->rh_timer.data) {
+               rh_status_dequeue (hcd, urb);
+               retval = 0;
+       } else {
+               retval = hcd->driver->urb_dequeue (hcd, urb);
+// FIXME:  if retval and we tried to splice, whoa!!
+if (retval && urb->status == -ENOENT) err ("whoa! retval %d", retval);
+       }
+
+       /* block till giveback, if needed */
+       if (!(urb->transfer_flags & (USB_ASYNC_UNLINK|USB_TIMEOUT_KILLED))
+                       && HCD_IS_RUNNING (hcd->state)
+                       && !retval) {
+               wait_for_completion (&splice.done);
+       } else if ((urb->transfer_flags & USB_ASYNC_UNLINK) && retval == 0) {
+               return -EINPROGRESS;
+       }
+       goto bye;
+done:
+       spin_unlock (&hcd_data_lock);
+       spin_unlock_irqrestore (&urb->lock, flags);
+bye:
+       if (retval)
+               dbg ("%s: hcd_unlink_urb fail %d",
+                   hcd ? hcd->bus->bus_name : "(no bus?)",
+                   retval);
+       return retval;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* called by khubd, rmmod, apmd, or other thread for hcd-private cleanup */
+
+// FIXME:  likely best to have explicit per-setting (config+alt)
+// setup primitives in the usbcore-to-hcd driver API, so nothing
+// is implicit.  kernel 2.5 needs a bunch of config cleanup...
+
+static int hcd_free_dev (struct usb_device *udev)
+{
+       struct hcd_dev          *dev;
+       struct usb_hcd          *hcd;
+       unsigned long           flags;
+
+       if (!udev || !udev->hcpriv)
+               return -EINVAL;
+
+       if (!udev->bus || !udev->bus->hcpriv)
+               return -ENODEV;
+
+       // should udev->devnum == -1 ??
+
+       dev = udev->hcpriv;
+       hcd = udev->bus->hcpriv;
+
+       /* device driver problem with refcounts? */
+       if (!list_empty (&dev->urb_list)) {
+               dbg ("free busy dev, %s devnum %d (bug!)",
+                       hcd->bus->bus_name, udev->devnum);
+               return -EINVAL;
+       }
+
+       hcd->driver->free_config (hcd, udev);
+
+       spin_lock_irqsave (&hcd_data_lock, flags);
+       list_del (&dev->dev_list);
+       udev->hcpriv = NULL;
+       spin_unlock_irqrestore (&hcd_data_lock, flags);
+
+       kfree (dev);
+       return 0;
+}
+
+static struct usb_operations hcd_operations = {
+       allocate:               hcd_alloc_dev,
+       get_frame_number:       hcd_get_frame_number,
+       submit_urb:             hcd_submit_urb,
+       unlink_urb:             hcd_unlink_urb,
+       deallocate:             hcd_free_dev,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static void hcd_irq (int irq, void *__hcd, struct pt_regs * r)
+{
+       struct usb_hcd          *hcd = __hcd;
+       int                     start = hcd->state;
+
+       if (unlikely (hcd->state == USB_STATE_HALT))    /* irq sharing? */
+               return;
+
+       hcd->driver->irq (hcd, r);
+       if (hcd->state != start && hcd->state == USB_STATE_HALT)
+               hc_died (hcd);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/**
+ * usb_hcd_giveback_urb - return URB from HCD to device driver
+ * @hcd: host controller returning the URB
+ * @urb: urb being returned to the USB device driver.
+ * @regs: saved hardware registers (ignored on 2.4 kernels)
+ * Context: in_interrupt()
+ *
+ * This hands the URB from HCD to its USB device driver, using its
+ * completion function.  The HCD has freed all per-urb resources
+ * (and is done using urb->hcpriv).  It also released all HCD locks;
+ * the device driver won't cause deadlocks if it resubmits this URB,
+ * and won't confuse things by modifying and resubmitting this one.
+ * Bandwidth and other resources will be deallocated.
+ *
+ * HCDs must not use this for periodic URBs that are still scheduled
+ * and will be reissued.  They should just call their completion handlers
+ * until the urb is returned to the device driver by unlinking.
+ *
+ * NOTE that no urb->next processing is done, even for isochronous URBs.
+ * ISO streaming functionality can be achieved by having completion handlers
+ * re-queue URBs.  Such explicit queuing doesn't discard error reports.
+ */
+void usb_hcd_giveback_urb (struct usb_hcd *hcd, struct urb *urb, struct pt_regs *regs)
+{
+       int is_root_hub_operation;
+
+       /* Work this out here as urb_unlink clears urb->dev */
+       is_root_hub_operation = (urb->dev == hcd->bus->root_hub);
+
+       urb_unlink (urb);
+
+       // NOTE:  a generic device/urb monitoring hook would go here.
+       // hcd_monitor_hook(MONITOR_URB_FINISH, urb, dev)
+       // It would catch exit/unlink paths for all urbs, but non-exit
+       // completions for periodic urbs need hooks inside the HCD.
+       // hcd_monitor_hook(MONITOR_URB_UPDATE, urb, dev)
+
+       // NOTE:  2.5 does this if !URB_NO_DMA_MAP transfer flag
+
+#ifdef CONFIG_PCI      
+       /* For 2.4, don't unmap bounce buffer if it's a root hub operation. */
+       if (usb_pipecontrol (urb->pipe) && !is_root_hub_operation)
+               pci_unmap_single (hcd->pdev, urb->setup_dma,
+                               sizeof (struct usb_ctrlrequest),
+                               PCI_DMA_TODEVICE);
+
+       if ((urb->transfer_buffer_length != 0) && !is_root_hub_operation)
+               pci_unmap_single (hcd->pdev, urb->transfer_dma,
+                               urb->transfer_buffer_length,
+                               usb_pipein (urb->pipe)
+                                   ? PCI_DMA_FROMDEVICE
+                                   : PCI_DMA_TODEVICE);
+#endif
+
+       /* pass ownership to the completion handler */
+       urb->complete (urb);
+}
+EXPORT_SYMBOL (usb_hcd_giveback_urb);