USB: fix race in HCD removal

[pandora-kernel.git] / drivers / usb / core / hcd.c

/*
 * (C) Copyright Linus Torvalds 1999
 * (C) Copyright Johannes Erdfelt 1999-2001
 * (C) Copyright Andreas Gal 1999
 * (C) Copyright Gregory P. Smith 1999
 * (C) Copyright Deti Fliegl 1999
 * (C) Copyright Randy Dunlap 2000
 * (C) Copyright David Brownell 2000-2002
 * 
 * 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/module.h>
#include <linux/version.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/completion.h>
#include <linux/utsname.h>
#include <linux/mm.h>
#include <asm/io.h>
#include <asm/scatterlist.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/mutex.h>
#include <asm/irq.h>
#include <asm/byteorder.h>
#include <linux/platform_device.h>

#include <linux/usb.h>

#include "usb.h"
#include "hcd.h"
#include "hub.h"


/*-------------------------------------------------------------------------*/

/*
 * USB Host Controller Driver framework
 *
 * Plugs into usbcore (usb_bus) and lets HCDs share code, minimizing
 * HCD-specific behaviors/bugs.
 *
 * 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, Greg Kroah-Hartman, ...
 *
 * HISTORY:
 * 2002-02-21   Pull in most of the usb_bus support from usb.c; some
 *              associated cleanup.  "usb_hcd" still != "usb_bus".
 * 2001-12-12   Initial patch version for Linux 2.5.1 kernel.
 */

/*-------------------------------------------------------------------------*/

/* host controllers we manage */
LIST_HEAD (usb_bus_list);
EXPORT_SYMBOL_GPL (usb_bus_list);

/* used when allocating bus numbers */
#define USB_MAXBUS              64
struct usb_busmap {
        unsigned long busmap [USB_MAXBUS / (8*sizeof (unsigned long))];
};
static struct usb_busmap busmap;

/* used when updating list of hcds */
DEFINE_MUTEX(usb_bus_list_lock);        /* exported only for usbfs */
EXPORT_SYMBOL_GPL (usb_bus_list_lock);

/* used for controlling access to virtual root hubs */
static DEFINE_SPINLOCK(hcd_root_hub_lock);

/* used when updating hcd data */
static DEFINE_SPINLOCK(hcd_data_lock);

/* wait queue for synchronous unlinks */
DECLARE_WAIT_QUEUE_HEAD(usb_kill_urb_queue);

/*-------------------------------------------------------------------------*/

/*
 * 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, /*  __le16 bcdUSB; v2.0 */

        0x09,       /*  __u8  bDeviceClass; HUB_CLASSCODE */
        0x00,       /*  __u8  bDeviceSubClass; */
        0x01,       /*  __u8  bDeviceProtocol; [ usb 2.0 single TT ]*/
        0x40,       /*  __u8  bMaxPacketSize0; 64 Bytes */

        0x00, 0x00, /*  __le16 idVendor; */
        0x00, 0x00, /*  __le16 idProduct; */
        KERNEL_VER, KERNEL_REL, /*  __le16 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, /*  __le16 bcdUSB; v1.1 */

        0x09,       /*  __u8  bDeviceClass; HUB_CLASSCODE */
        0x00,       /*  __u8  bDeviceSubClass; */
        0x00,       /*  __u8  bDeviceProtocol; [ low/full speeds only ] */
        0x40,       /*  __u8  bMaxPacketSize0; 64 Bytes */

        0x00, 0x00, /*  __le16 idVendor; */
        0x00, 0x00, /*  __le16 idProduct; */
        KERNEL_VER, KERNEL_REL, /*  __le16 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, /*  __le16 wTotalLength; */
        0x01,       /*  __u8  bNumInterfaces; (1) */
        0x01,       /*  __u8  bConfigurationValue; */
        0x00,       /*  __u8  iConfiguration; */
        0xc0,       /*  __u8  bmAttributes; 
                                 Bit 7: must be set,
                                     6: Self-powered,
                                     5: Remote wakeup,
                                     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, /*  __le16 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, /*  __le16 wTotalLength; */
        0x01,       /*  __u8  bNumInterfaces; (1) */
        0x01,       /*  __u8  bConfigurationValue; */
        0x00,       /*  __u8  iConfiguration; */
        0xc0,       /*  __u8  bmAttributes; 
                                 Bit 7: must be set,
                                     6: Self-powered,
                                     5: Remote wakeup,
                                     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 */
                    /* __le16 ep_wMaxPacketSize; 1 + (MAX_ROOT_PORTS / 8)
                     * see hub.c:hub_configure() for details. */
        (USB_MAXCHILDREN + 1 + 7) / 8, 0x00,
        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;
        }
        if (utfmax > 0) {
                *utf = *s;
                ++retval;
        }
        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)
 * @hcd: the host controller for this root hub
 * @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) {
                buf[0] = 4;    buf[1] = 3;      /* 4 bytes string data */
                buf[2] = 0x09; buf[3] = 0x04;   /* MSFT-speak for "en-us" */
                len = min (len, 4);
                memcpy (data, buf, len);
                return len;

        // serial number
        } else if (id == 1) {
                strlcpy (buf, hcd->self.bus_name, sizeof buf);

        // product description
        } else if (id == 2) {
                strlcpy (buf, hcd->product_desc, sizeof buf);

        // id 3 == vendor description
        } else if (id == 3) {
                snprintf (buf, sizeof buf, "%s %s %s", init_utsname()->sysname,
                        init_utsname()->release, hcd->driver->description);

        // unsupported IDs --> "protocol stall"
        } else
                return -EPIPE;

        switch (len) {          /* All cases fall through */
        default:
                len = 2 + ascii2utf (buf, data + 2, len - 2);
        case 2:
                data [1] = 3;   /* type == string */
        case 1:
                data [0] = 2 * (strlen (buf) + 1);
        case 0:
                ;               /* Compiler wants a statement here */
        }
        return len;
}


/* Root hub control transfers execute synchronously */
static int rh_call_control (struct usb_hcd *hcd, struct urb *urb)
{
        struct usb_ctrlrequest *cmd;
        u16             typeReq, wValue, wIndex, wLength;
        u8              *ubuf = urb->transfer_buffer;
        u8              tbuf [sizeof (struct usb_hub_descriptor)]
                __attribute__((aligned(4)));
        const u8        *bufp = tbuf;
        int             len = 0;
        int             patch_wakeup = 0;
        unsigned long   flags;
        int             status = 0;
        int             n;

        cmd = (struct usb_ctrlrequest *) urb->setup_packet;
        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;

        urb->actual_length = 0;
        switch (typeReq) {

        /* DEVICE REQUESTS */

        /* The root hub's remote wakeup enable bit is implemented using
         * driver model wakeup flags.  If this system supports wakeup
         * through USB, userspace may change the default "allow wakeup"
         * policy through sysfs or these calls.
         *
         * Most root hubs support wakeup from downstream devices, for
         * runtime power management (disabling USB clocks and reducing
         * VBUS power usage).  However, not all of them do so; silicon,
         * board, and BIOS bugs here are not uncommon, so these can't
         * be treated quite like external hubs.
         *
         * Likewise, not all root hubs will pass wakeup events upstream,
         * to wake up the whole system.  So don't assume root hub and
         * controller capabilities are identical.
         */

        case DeviceRequest | USB_REQ_GET_STATUS:
                tbuf [0] = (device_may_wakeup(&hcd->self.root_hub->dev)
                                        << USB_DEVICE_REMOTE_WAKEUP)
                                | (1 << USB_DEVICE_SELF_POWERED);
                tbuf [1] = 0;
                len = 2;
                break;
        case DeviceOutRequest | USB_REQ_CLEAR_FEATURE:
                if (wValue == USB_DEVICE_REMOTE_WAKEUP)
                        device_set_wakeup_enable(&hcd->self.root_hub->dev, 0);
                else
                        goto error;
                break;
        case DeviceOutRequest | USB_REQ_SET_FEATURE:
                if (device_can_wakeup(&hcd->self.root_hub->dev)
                                && wValue == USB_DEVICE_REMOTE_WAKEUP)
                        device_set_wakeup_enable(&hcd->self.root_hub->dev, 1);
                else
                        goto error;
                break;
        case DeviceRequest | USB_REQ_GET_CONFIGURATION:
                tbuf [0] = 1;
                len = 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;
                        }
                        if (device_can_wakeup(&hcd->self.root_hub->dev))
                                patch_wakeup = 1;
                        break;
                case USB_DT_STRING << 8:
                        n = rh_string (wValue & 0xff, hcd, ubuf, wLength);
                        if (n < 0)
                                goto error;
                        urb->actual_length = n;
                        break;
                default:
                        goto error;
                }
                break;
        case DeviceRequest | USB_REQ_GET_INTERFACE:
                tbuf [0] = 0;
                len = 1;
                        /* FALLTHROUGH */
        case DeviceOutRequest | USB_REQ_SET_INTERFACE:
                break;
        case DeviceOutRequest | USB_REQ_SET_ADDRESS:
                // wValue == urb->dev->devaddr
                dev_dbg (hcd->self.controller, "root hub device address %d\n",
                        wValue);
                break;

        /* INTERFACE REQUESTS (no defined feature/status flags) */

        /* ENDPOINT REQUESTS */

        case EndpointRequest | USB_REQ_GET_STATUS:
                // ENDPOINT_HALT flag
                tbuf [0] = 0;
                tbuf [1] = 0;
                len = 2;
                        /* FALLTHROUGH */
        case EndpointOutRequest | USB_REQ_CLEAR_FEATURE:
        case EndpointOutRequest | USB_REQ_SET_FEATURE:
                dev_dbg (hcd->self.controller, "no endpoint features yet\n");
                break;

        /* CLASS REQUESTS (and errors) */

        default:
                /* non-generic request */
                switch (typeReq) {
                case GetHubStatus:
                case GetPortStatus:
                        len = 4;
                        break;
                case GetHubDescriptor:
                        len = sizeof (struct usb_hub_descriptor);
                        break;
                }
                status = hcd->driver->hub_control (hcd,
                        typeReq, wValue, wIndex,
                        tbuf, wLength);
                break;
error:
                /* "protocol stall" on error */
                status = -EPIPE;
        }

        if (status) {
                len = 0;
                if (status != -EPIPE) {
                        dev_dbg (hcd->self.controller,
                                "CTRL: TypeReq=0x%x val=0x%x "
                                "idx=0x%x len=%d ==> %d\n",
                                typeReq, wValue, wIndex,
                                wLength, status);
                }
        }
        if (len) {
                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);

                /* report whether RH hardware supports remote wakeup */
                if (patch_wakeup &&
                                len > offsetof (struct usb_config_descriptor,
                                                bmAttributes))
                        ((struct usb_config_descriptor *)ubuf)->bmAttributes
                                |= USB_CONFIG_ATT_WAKEUP;
        }

        /* any errors get returned through the urb completion */
        local_irq_save (flags);
        spin_lock (&urb->lock);
        if (urb->status == -EINPROGRESS)
                urb->status = status;
        spin_unlock (&urb->lock);
        usb_hcd_giveback_urb (hcd, urb);
        local_irq_restore (flags);
        return 0;
}

/*-------------------------------------------------------------------------*/

/*
 * Root Hub interrupt transfers are polled using a timer if the
 * driver requests it; otherwise the driver is responsible for
 * calling usb_hcd_poll_rh_status() when an event occurs.
 *
 * Completions are called in_interrupt(), but they may or may not
 * be in_irq().
 */
void usb_hcd_poll_rh_status(struct usb_hcd *hcd)
{
        struct urb      *urb;
        int             length;
        unsigned long   flags;
        char            buffer[4];      /* Any root hubs with > 31 ports? */

        if (unlikely(!hcd->rh_registered))
                return;
        if (!hcd->uses_new_polling && !hcd->status_urb)
                return;

        length = hcd->driver->hub_status_data(hcd, buffer);
        if (length > 0) {

                /* try to complete the status urb */
                local_irq_save (flags);
                spin_lock(&hcd_root_hub_lock);
                urb = hcd->status_urb;
                if (urb) {
                        spin_lock(&urb->lock);
                        if (urb->status == -EINPROGRESS) {
                                hcd->poll_pending = 0;
                                hcd->status_urb = NULL;
                                urb->status = 0;
                                urb->hcpriv = NULL;
                                urb->actual_length = length;
                                memcpy(urb->transfer_buffer, buffer, length);
                        } else          /* urb has been unlinked */
                                length = 0;
                        spin_unlock(&urb->lock);
                } else
                        length = 0;
                spin_unlock(&hcd_root_hub_lock);

                /* local irqs are always blocked in completions */
                if (length > 0)
                        usb_hcd_giveback_urb (hcd, urb);
                else
                        hcd->poll_pending = 1;
                local_irq_restore (flags);
        }

        /* The USB 2.0 spec says 256 ms.  This is close enough and won't
         * exceed that limit if HZ is 100. */
        if (hcd->uses_new_polling ? hcd->poll_rh :
                        (length == 0 && hcd->status_urb != NULL))
                mod_timer (&hcd->rh_timer, jiffies + msecs_to_jiffies(250));
}
EXPORT_SYMBOL_GPL(usb_hcd_poll_rh_status);

/* timer callback */
static void rh_timer_func (unsigned long _hcd)
{
        usb_hcd_poll_rh_status((struct usb_hcd *) _hcd);
}

/*-------------------------------------------------------------------------*/

static int rh_queue_status (struct usb_hcd *hcd, struct urb *urb)
{
        int             retval;
        unsigned long   flags;
        int             len = 1 + (urb->dev->maxchild / 8);

        spin_lock_irqsave (&hcd_root_hub_lock, flags);
        if (urb->status != -EINPROGRESS)        /* already unlinked */
                retval = urb->status;
        else if (hcd->status_urb || urb->transfer_buffer_length < len) {
                dev_dbg (hcd->self.controller, "not queuing rh status urb\n");
                retval = -EINVAL;
        } else {
                hcd->status_urb = urb;
                urb->hcpriv = hcd;      /* indicate it's queued */

                if (!hcd->uses_new_polling)
                        mod_timer (&hcd->rh_timer, jiffies +
                                        msecs_to_jiffies(250));

                /* If a status change has already occurred, report it ASAP */
                else if (hcd->poll_pending)
                        mod_timer (&hcd->rh_timer, jiffies);
                retval = 0;
        }
        spin_unlock_irqrestore (&hcd_root_hub_lock, flags);
        return retval;
}

static int rh_urb_enqueue (struct usb_hcd *hcd, struct urb *urb)
{
        if (usb_pipeint (urb->pipe))
                return rh_queue_status (hcd, urb);
        if (usb_pipecontrol (urb->pipe))
                return rh_call_control (hcd, urb);
        return -EINVAL;
}

/*-------------------------------------------------------------------------*/

/* Unlinks of root-hub control URBs are legal, but they don't do anything
 * since these URBs always execute synchronously.
 */
static int usb_rh_urb_dequeue (struct usb_hcd *hcd, struct urb *urb)
{
        unsigned long   flags;

        if (usb_pipeendpoint(urb->pipe) == 0) { /* Control URB */
                ;       /* Do nothing */

        } else {                                /* Status URB */
                if (!hcd->uses_new_polling)
                        del_timer (&hcd->rh_timer);
                local_irq_save (flags);
                spin_lock (&hcd_root_hub_lock);
                if (urb == hcd->status_urb) {
                        hcd->status_urb = NULL;
                        urb->hcpriv = NULL;
                } else
                        urb = NULL;             /* wasn't fully queued */
                spin_unlock (&hcd_root_hub_lock);
                if (urb)
                        usb_hcd_giveback_urb (hcd, urb);
                local_irq_restore (flags);
        }

        return 0;
}

/*-------------------------------------------------------------------------*/

static struct class *usb_host_class;

int usb_host_init(void)
{
        int retval = 0;

        usb_host_class = class_create(THIS_MODULE, "usb_host");
        if (IS_ERR(usb_host_class))
                retval = PTR_ERR(usb_host_class);
        return retval;
}

void usb_host_cleanup(void)
{
        class_destroy(usb_host_class);
}

/**
 * usb_bus_init - shared initialization code
 * @bus: the bus structure being initialized
 *
 * This code is used to initialize a usb_bus structure, memory for which is
 * separately managed.
 */
static void usb_bus_init (struct usb_bus *bus)
{
        memset (&bus->devmap, 0, sizeof(struct usb_devmap));

        bus->devnum_next = 1;

        bus->root_hub = NULL;
        bus->busnum = -1;
        bus->bandwidth_allocated = 0;
        bus->bandwidth_int_reqs  = 0;
        bus->bandwidth_isoc_reqs = 0;

        INIT_LIST_HEAD (&bus->bus_list);
}

/*-------------------------------------------------------------------------*/

/**
 * usb_register_bus - registers the USB host controller with the usb core
 * @bus: pointer to the bus to register
 * Context: !in_interrupt()
 *
 * Assigns a bus number, and links the controller into usbcore data
 * structures so that it can be seen by scanning the bus list.
 */
static int usb_register_bus(struct usb_bus *bus)
{
        int busnum;

        mutex_lock(&usb_bus_list_lock);
        busnum = find_next_zero_bit (busmap.busmap, USB_MAXBUS, 1);
        if (busnum < USB_MAXBUS) {
                set_bit (busnum, busmap.busmap);
                bus->busnum = busnum;
        } else {
                printk (KERN_ERR "%s: too many buses\n", usbcore_name);
                mutex_unlock(&usb_bus_list_lock);
                return -E2BIG;
        }

        bus->class_dev = class_device_create(usb_host_class, NULL, MKDEV(0,0),
                                             bus->controller, "usb_host%d", busnum);
        if (IS_ERR(bus->class_dev)) {
                clear_bit(busnum, busmap.busmap);
                mutex_unlock(&usb_bus_list_lock);
                return PTR_ERR(bus->class_dev);
        }

        class_set_devdata(bus->class_dev, bus);

        /* Add it to the local list of buses */
        list_add (&bus->bus_list, &usb_bus_list);
        mutex_unlock(&usb_bus_list_lock);

        usb_notify_add_bus(bus);

        dev_info (bus->controller, "new USB bus registered, assigned bus number %d\n", bus->busnum);
        return 0;
}

/**
 * usb_deregister_bus - deregisters the USB host controller
 * @bus: pointer to the bus to deregister
 * Context: !in_interrupt()
 *
 * Recycles the bus number, and unlinks the controller from usbcore data
 * structures so that it won't be seen by scanning the bus list.
 */
static void usb_deregister_bus (struct usb_bus *bus)
{
        dev_info (bus->controller, "USB bus %d deregistered\n", bus->busnum);

        /*
         * NOTE: make sure that all the devices are removed by the
         * controller code, as well as having it call this when cleaning
         * itself up
         */
        mutex_lock(&usb_bus_list_lock);
        list_del (&bus->bus_list);
        mutex_unlock(&usb_bus_list_lock);

        usb_notify_remove_bus(bus);

        clear_bit (bus->busnum, busmap.busmap);

        class_device_unregister(bus->class_dev);
}

/**
 * register_root_hub - called by usb_add_hcd() to register a root hub
 * @hcd: host controller for this root hub
 *
 * This function registers the root hub with the USB subsystem.  It sets up
 * the device properly in the device tree and then calls usb_new_device()
 * to register the usb device.  It also assigns the root hub's USB address
 * (always 1).
 */
static int register_root_hub(struct usb_hcd *hcd)
{
        struct device *parent_dev = hcd->self.controller;
        struct usb_device *usb_dev = hcd->self.root_hub;
        const int devnum = 1;
        int retval;

        usb_dev->devnum = devnum;
        usb_dev->bus->devnum_next = devnum + 1;
        memset (&usb_dev->bus->devmap.devicemap, 0,
                        sizeof usb_dev->bus->devmap.devicemap);
        set_bit (devnum, usb_dev->bus->devmap.devicemap);
        usb_set_device_state(usb_dev, USB_STATE_ADDRESS);

        mutex_lock(&usb_bus_list_lock);

        usb_dev->ep0.desc.wMaxPacketSize = __constant_cpu_to_le16(64);
        retval = usb_get_device_descriptor(usb_dev, USB_DT_DEVICE_SIZE);
        if (retval != sizeof usb_dev->descriptor) {
                mutex_unlock(&usb_bus_list_lock);
                dev_dbg (parent_dev, "can't read %s device descriptor %d\n",
                                usb_dev->dev.bus_id, retval);
                return (retval < 0) ? retval : -EMSGSIZE;
        }

        retval = usb_new_device (usb_dev);
        if (retval) {
                dev_err (parent_dev, "can't register root hub for %s, %d\n",
                                usb_dev->dev.bus_id, retval);
        }
        mutex_unlock(&usb_bus_list_lock);

        if (retval == 0) {
                spin_lock_irq (&hcd_root_hub_lock);
                hcd->rh_registered = 1;
                spin_unlock_irq (&hcd_root_hub_lock);

                /* Did the HC die before the root hub was registered? */
                if (hcd->state == HC_STATE_HALT)
                        usb_hc_died (hcd);      /* This time clean up */
        }

        return retval;
}

void usb_enable_root_hub_irq (struct usb_bus *bus)
{
        struct usb_hcd *hcd;

        hcd = container_of (bus, struct usb_hcd, self);
        if (hcd->driver->hub_irq_enable && hcd->state != HC_STATE_HALT)
                hcd->driver->hub_irq_enable (hcd);
}


/*-------------------------------------------------------------------------*/

/**
 * usb_calc_bus_time - approximate periodic transaction time in nanoseconds
 * @speed: from dev->speed; USB_SPEED_{LOW,FULL,HIGH}
 * @is_input: true iff the transaction sends data to the host
 * @isoc: true for isochronous transactions, false for interrupt ones
 * @bytecount: how many bytes in the transaction.
 *
 * Returns approximate bus time in nanoseconds for a periodic transaction.
 * See USB 2.0 spec section 5.11.3; only periodic transfers need to be
 * scheduled in software, this function is only used for such scheduling.
 */
long usb_calc_bus_time (int speed, int is_input, int isoc, int bytecount)
{
        unsigned long   tmp;

        switch (speed) {
        case USB_SPEED_LOW:     /* INTR only */
                if (is_input) {
                        tmp = (67667L * (31L + 10L * BitTime (bytecount))) / 1000L;
                        return (64060L + (2 * BW_HUB_LS_SETUP) + BW_HOST_DELAY + tmp);
                } else {
                        tmp = (66700L * (31L + 10L * BitTime (bytecount))) / 1000L;
                        return (64107L + (2 * BW_HUB_LS_SETUP) + BW_HOST_DELAY + tmp);
                }
        case USB_SPEED_FULL:    /* ISOC or INTR */
                if (isoc) {
                        tmp = (8354L * (31L + 10L * BitTime (bytecount))) / 1000L;
                        return (((is_input) ? 7268L : 6265L) + BW_HOST_DELAY + tmp);
                } else {
                        tmp = (8354L * (31L + 10L * BitTime (bytecount))) / 1000L;
                        return (9107L + BW_HOST_DELAY + tmp);
                }
        case USB_SPEED_HIGH:    /* ISOC or INTR */
                // FIXME adjust for input vs output
                if (isoc)
                        tmp = HS_NSECS_ISO (bytecount);
                else
                        tmp = HS_NSECS (bytecount);
                return tmp;
        default:
                pr_debug ("%s: bogus device speed!\n", usbcore_name);
                return -1;
        }
}
EXPORT_SYMBOL (usb_calc_bus_time);


/*-------------------------------------------------------------------------*/

/*
 * Generic HC operations.
 */

/*-------------------------------------------------------------------------*/

static void urb_unlink (struct urb *urb)
{
        unsigned long           flags;

        /* clear all state linking urb to this dev (and hcd) */

        spin_lock_irqsave (&hcd_data_lock, flags);
        list_del_init (&urb->urb_list);
        spin_unlock_irqrestore (&hcd_data_lock, flags);
}


/* may be called in any context with a valid urb->dev usecount
 * caller surrenders "ownership" of urb
 * expects usb_submit_urb() to have sanity checked and conditioned all
 * inputs in the urb
 */
int usb_hcd_submit_urb (struct urb *urb, gfp_t mem_flags)
{
        int                     status;
        struct usb_hcd          *hcd = bus_to_hcd(urb->dev->bus);
        struct usb_host_endpoint *ep;
        unsigned long           flags;

        if (!hcd)
                return -ENODEV;

        usbmon_urb_submit(&hcd->self, urb);

        /*
         * 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);
        ep = (usb_pipein(urb->pipe) ? urb->dev->ep_in : urb->dev->ep_out)
                        [usb_pipeendpoint(urb->pipe)];
        if (unlikely (!ep))
                status = -ENOENT;
        else if (unlikely (urb->reject))
                status = -EPERM;
        else switch (hcd->state) {
        case HC_STATE_RUNNING:
        case HC_STATE_RESUMING:
doit:
                list_add_tail (&urb->urb_list, &ep->urb_list);
                status = 0;
                break;
        case HC_STATE_SUSPENDED:
                /* HC upstream links (register access, wakeup signaling) can work
                 * even when the downstream links (and DMA etc) are quiesced; let
                 * usbcore talk to the root hub.
                 */
                if (hcd->self.controller->power.power_state.event == PM_EVENT_ON
                                && urb->dev->parent == NULL)
                        goto doit;
                /* FALL THROUGH */
        default:
                status = -ESHUTDOWN;
                break;
        }
        spin_unlock_irqrestore (&hcd_data_lock, flags);
        if (status) {
                INIT_LIST_HEAD (&urb->urb_list);
                usbmon_urb_submit_error(&hcd->self, urb, status);
                return status;
        }

        /* increment urb's reference count as part of giving it to the HCD
         * (which now controls it).  HCD guarantees that it either returns
         * an error or calls giveback(), but not both.
         */
        urb = usb_get_urb (urb);
        atomic_inc (&urb->use_count);

        if (urb->dev == hcd->self.root_hub) {
                /* NOTE:  requirement on hub callers (usbfs and the hub
                 * driver, for now) that URBs' urb->transfer_buffer be
                 * valid and usb_buffer_{sync,unmap}() not be needed, since
                 * they could clobber root hub response data.
                 */
                status = rh_urb_enqueue (hcd, urb);
                goto done;
        }

        /* lower level hcd code should use *_dma exclusively,
         * unless it uses pio or talks to another transport.
         */
        if (hcd->self.uses_dma) {
                if (usb_pipecontrol (urb->pipe)
                        && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
                        urb->setup_dma = dma_map_single (
                                        hcd->self.controller,
                                        urb->setup_packet,
                                        sizeof (struct usb_ctrlrequest),
                                        DMA_TO_DEVICE);
                if (urb->transfer_buffer_length != 0
                        && !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
                        urb->transfer_dma = dma_map_single (
                                        hcd->self.controller,
                                        urb->transfer_buffer,
                                        urb->transfer_buffer_length,
                                        usb_pipein (urb->pipe)
                                            ? DMA_FROM_DEVICE
                                            : DMA_TO_DEVICE);
        }

        status = hcd->driver->urb_enqueue (hcd, ep, urb, mem_flags);
done:
        if (unlikely (status)) {
                urb_unlink (urb);
                atomic_dec (&urb->use_count);
                if (urb->reject)
                        wake_up (&usb_kill_urb_queue);
                usb_put_urb (urb);
                usbmon_urb_submit_error(&hcd->self, urb, status);
        }
        return status;
}

/*-------------------------------------------------------------------------*/

/* called in any context */
int usb_hcd_get_frame_number (struct usb_device *udev)
{
        struct usb_hcd  *hcd = bus_to_hcd(udev->bus);

        if (!HC_IS_RUNNING (hcd->state))
                return -ESHUTDOWN;
        return hcd->driver->get_frame_number (hcd);
}

/*-------------------------------------------------------------------------*/

/* this makes the hcd giveback() the urb more quickly, by kicking it
 * off hardware queues (which may take a while) and returning it as
 * soon as practical.  we've already set up the urb's return status,
 * but we can't know if the callback completed already.
 */
static int
unlink1 (struct usb_hcd *hcd, struct urb *urb)
{
        int             value;

        if (urb->dev == hcd->self.root_hub)
                value = usb_rh_urb_dequeue (hcd, urb);
        else {

                /* The only reason an HCD might fail this call is if
                 * it has not yet fully queued the urb to begin with.
                 * Such failures should be harmless. */
                value = hcd->driver->urb_dequeue (hcd, urb);
        }

        if (value != 0)
                dev_dbg (hcd->self.controller, "dequeue %p --> %d\n",
                                urb, value);
        return value;
}

/*
 * called in any context
 *
 * caller guarantees urb won't be recycled till both unlink()
 * and the urb's completion function return
 */
int usb_hcd_unlink_urb (struct urb *urb, int status)
{
        struct usb_host_endpoint        *ep;
        struct usb_hcd                  *hcd = NULL;
        struct device                   *sys = NULL;
        unsigned long                   flags;
        struct list_head                *tmp;
        int                             retval;

        if (!urb)
                return -EINVAL;
        if (!urb->dev || !urb->dev->bus)
                return -ENODEV;
        ep = (usb_pipein(urb->pipe) ? urb->dev->ep_in : urb->dev->ep_out)
                        [usb_pipeendpoint(urb->pipe)];
        if (!ep)
                return -ENODEV;

        /*
         * 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);

        sys = &urb->dev->dev;
        hcd = bus_to_hcd(urb->dev->bus);
        if (hcd == NULL) {
                retval = -ENODEV;
                goto done;
        }

        /* insist the urb is still queued */
        list_for_each(tmp, &ep->urb_list) {
                if (tmp == &urb->urb_list)
                        break;
        }
        if (tmp != &urb->urb_list) {
                retval = -EIDRM;
                goto done;
        }

        /* Any status except -EINPROGRESS means something already started to
         * unlink this URB from the hardware.  So there's no more work to do.
         */
        if (urb->status != -EINPROGRESS) {
                retval = -EBUSY;
                goto done;
        }

        /* IRQ setup can easily be broken so that USB controllers
         * never get completion IRQs ... maybe even the ones we need to
         * finish unlinking the initial failed usb_set_address()
         * or device descriptor fetch.
         */
        if (!test_bit(HCD_FLAG_SAW_IRQ, &hcd->flags)
            && hcd->self.root_hub != urb->dev) {
                dev_warn (hcd->self.controller, "Unlink after no-IRQ?  "
                        "Controller is probably using the wrong IRQ."
                        "\n");
                set_bit(HCD_FLAG_SAW_IRQ, &hcd->flags);
        }

        urb->status = status;

        spin_unlock (&hcd_data_lock);
        spin_unlock_irqrestore (&urb->lock, flags);

        retval = unlink1 (hcd, urb);
        if (retval == 0)
                retval = -EINPROGRESS;
        return retval;

done:
        spin_unlock (&hcd_data_lock);
        spin_unlock_irqrestore (&urb->lock, flags);
        if (retval != -EIDRM && sys && sys->driver)
                dev_dbg (sys, "hcd_unlink_urb %p fail %d\n", urb, retval);
        return retval;
}

/*-------------------------------------------------------------------------*/

/* disables the endpoint: cancels any pending urbs, then synchronizes with
 * the hcd to make sure all endpoint state is gone from hardware, and then
 * waits until the endpoint's queue is completely drained. use for
 * set_configuration, set_interface, driver removal, physical disconnect.
 *
 * example:  a qh stored in ep->hcpriv, holding state related to endpoint
 * type, maxpacket size, toggle, halt status, and scheduling.
 */
void usb_hcd_endpoint_disable (struct usb_device *udev,
                struct usb_host_endpoint *ep)
{
        struct usb_hcd          *hcd;
        struct urb              *urb;

        hcd = bus_to_hcd(udev->bus);

        WARN_ON (!HC_IS_RUNNING (hcd->state) && hcd->state != HC_STATE_HALT &&
                        udev->state != USB_STATE_NOTATTACHED);

        local_irq_disable ();

        /* ep is already gone from udev->ep_{in,out}[]; no more submits */
rescan:
        spin_lock (&hcd_data_lock);
        list_for_each_entry (urb, &ep->urb_list, urb_list) {
                int     tmp;

                /* the urb may already have been unlinked */
                if (urb->status != -EINPROGRESS)
                        continue;
                usb_get_urb (urb);
                spin_unlock (&hcd_data_lock);

                spin_lock (&urb->lock);
                tmp = urb->status;
                if (tmp == -EINPROGRESS)
                        urb->status = -ESHUTDOWN;
                spin_unlock (&urb->lock);

                /* kick hcd unless it's already returning this */
                if (tmp == -EINPROGRESS) {
                        tmp = urb->pipe;
                        unlink1 (hcd, urb);
                        dev_dbg (hcd->self.controller,
                                "shutdown urb %p pipe %08x ep%d%s%s\n",
                                urb, tmp, usb_pipeendpoint (tmp),
                                (tmp & USB_DIR_IN) ? "in" : "out",
                                ({ char *s; \
                                 switch (usb_pipetype (tmp)) { \
                                 case PIPE_CONTROL:     s = ""; break; \
                                 case PIPE_BULK:        s = "-bulk"; break; \
                                 case PIPE_INTERRUPT:   s = "-intr"; break; \
                                 default:               s = "-iso"; break; \
                                }; s;}));
                }
                usb_put_urb (urb);

                /* list contents may have changed */
                goto rescan;
        }
        spin_unlock (&hcd_data_lock);
        local_irq_enable ();

        /* synchronize with the hardware, so old configuration state
         * clears out immediately (and will be freed).
         */
        might_sleep ();
        if (hcd->driver->endpoint_disable)
                hcd->driver->endpoint_disable (hcd, ep);

        /* Wait until the endpoint queue is completely empty.  Most HCDs
         * will have done this already in their endpoint_disable method,
         * but some might not.  And there could be root-hub control URBs
         * still pending since they aren't affected by the HCDs'
         * endpoint_disable methods.
         */
        while (!list_empty (&ep->urb_list)) {
                spin_lock_irq (&hcd_data_lock);

                /* The list may have changed while we acquired the spinlock */
                urb = NULL;
                if (!list_empty (&ep->urb_list)) {
                        urb = list_entry (ep->urb_list.prev, struct urb,
                                        urb_list);
                        usb_get_urb (urb);
                }
                spin_unlock_irq (&hcd_data_lock);

                if (urb) {
                        usb_kill_urb (urb);
                        usb_put_urb (urb);
                }
        }
}

/*-------------------------------------------------------------------------*/

#ifdef  CONFIG_PM

int hcd_bus_suspend (struct usb_bus *bus)
{
        struct usb_hcd          *hcd;
        int                     status;

        hcd = container_of (bus, struct usb_hcd, self);
        if (!hcd->driver->bus_suspend)
                return -ENOENT;
        hcd->state = HC_STATE_QUIESCING;
        status = hcd->driver->bus_suspend (hcd);
        if (status == 0)
                hcd->state = HC_STATE_SUSPENDED;
        else
                dev_dbg(&bus->root_hub->dev, "%s fail, err %d\n",
                                "suspend", status);
        return status;
}

int hcd_bus_resume (struct usb_bus *bus)
{
        struct usb_hcd          *hcd;
        int                     status;

        hcd = container_of (bus, struct usb_hcd, self);
        if (!hcd->driver->bus_resume)
                return -ENOENT;
        if (hcd->state == HC_STATE_RUNNING)
                return 0;
        hcd->state = HC_STATE_RESUMING;
        status = hcd->driver->bus_resume (hcd);
        if (status == 0)
                hcd->state = HC_STATE_RUNNING;
        else {
                dev_dbg(&bus->root_hub->dev, "%s fail, err %d\n",
                                "resume", status);
                usb_hc_died(hcd);
        }
        return status;
}

/**
 * usb_hcd_resume_root_hub - called by HCD to resume its root hub 
 * @hcd: host controller for this root hub
 *
 * The USB host controller calls this function when its root hub is
 * suspended (with the remote wakeup feature enabled) and a remote
 * wakeup request is received.  It queues a request for khubd to
 * resume the root hub (that is, manage its downstream ports again).
 */
void usb_hcd_resume_root_hub (struct usb_hcd *hcd)
{
        unsigned long flags;

        spin_lock_irqsave (&hcd_root_hub_lock, flags);
        if (hcd->rh_registered)
                usb_resume_root_hub (hcd->self.root_hub);
        spin_unlock_irqrestore (&hcd_root_hub_lock, flags);
}
EXPORT_SYMBOL_GPL(usb_hcd_resume_root_hub);

#endif

/*-------------------------------------------------------------------------*/

#ifdef  CONFIG_USB_OTG

/**
 * usb_bus_start_enum - start immediate enumeration (for OTG)
 * @bus: the bus (must use hcd framework)
 * @port_num: 1-based number of port; usually bus->otg_port
 * Context: in_interrupt()
 *
 * Starts enumeration, with an immediate reset followed later by
 * khubd identifying and possibly configuring the device.
 * This is needed by OTG controller drivers, where it helps meet
 * HNP protocol timing requirements for starting a port reset.
 */
int usb_bus_start_enum(struct usb_bus *bus, unsigned port_num)
{
        struct usb_hcd          *hcd;
        int                     status = -EOPNOTSUPP;

        /* NOTE: since HNP can't start by grabbing the bus's address0_sem,
         * boards with root hubs hooked up to internal devices (instead of
         * just the OTG port) may need more attention to resetting...
         */
        hcd = container_of (bus, struct usb_hcd, self);
        if (port_num && hcd->driver->start_port_reset)
                status = hcd->driver->start_port_reset(hcd, port_num);

        /* run khubd shortly after (first) root port reset finishes;
         * it may issue others, until at least 50 msecs have passed.
         */
        if (status == 0)
                mod_timer(&hcd->rh_timer, jiffies + msecs_to_jiffies(10));
        return status;
}
EXPORT_SYMBOL (usb_bus_start_enum);

#endif

/*-------------------------------------------------------------------------*/

/**
 * 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.
 * 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 problems if it frees, modifies,
 * or resubmits this URB.
 */
void usb_hcd_giveback_urb (struct usb_hcd *hcd, struct urb *urb)
{
        int at_root_hub;

        at_root_hub = (urb->dev == hcd->self.root_hub);
        urb_unlink (urb);

        /* lower level hcd code should use *_dma exclusively if the
         * host controller does DMA */
        if (hcd->self.uses_dma && !at_root_hub) {
                if (usb_pipecontrol (urb->pipe)
                        && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
                        dma_unmap_single (hcd->self.controller, urb->setup_dma,
                                        sizeof (struct usb_ctrlrequest),
                                        DMA_TO_DEVICE);
                if (urb->transfer_buffer_length != 0
                        && !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
                        dma_unmap_single (hcd->self.controller, 
                                        urb->transfer_dma,
                                        urb->transfer_buffer_length,
                                        usb_pipein (urb->pipe)
                                            ? DMA_FROM_DEVICE
                                            : DMA_TO_DEVICE);
        }

        usbmon_urb_complete (&hcd->self, urb);
        /* pass ownership to the completion handler */
        urb->complete (urb);
        atomic_dec (&urb->use_count);
        if (unlikely (urb->reject))
                wake_up (&usb_kill_urb_queue);
        usb_put_urb (urb);
}
EXPORT_SYMBOL (usb_hcd_giveback_urb);

/*-------------------------------------------------------------------------*/

/**
 * usb_hcd_irq - hook IRQs to HCD framework (bus glue)
 * @irq: the IRQ being raised
 * @__hcd: pointer to the HCD whose IRQ is being signaled
 * @r: saved hardware registers
 *
 * If the controller isn't HALTed, calls the driver's irq handler.
 * Checks whether the controller is now dead.
 */
irqreturn_t usb_hcd_irq (int irq, void *__hcd)
{
        struct usb_hcd          *hcd = __hcd;
        int                     start = hcd->state;

        if (unlikely(start == HC_STATE_HALT ||
            !test_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags)))
                return IRQ_NONE;
        if (hcd->driver->irq (hcd) == IRQ_NONE)
                return IRQ_NONE;

        set_bit(HCD_FLAG_SAW_IRQ, &hcd->flags);

        if (unlikely(hcd->state == HC_STATE_HALT))
                usb_hc_died (hcd);
        return IRQ_HANDLED;
}

/*-------------------------------------------------------------------------*/

/**
 * usb_hc_died - report abnormal shutdown of a host controller (bus glue)
 * @hcd: pointer to the HCD representing the controller
 *
 * This is called by bus glue to report a USB host controller that died
 * while operations may still have been pending.  It's called automatically
 * by the PCI glue, so only glue for non-PCI busses should need to call it. 
 */
void usb_hc_died (struct usb_hcd *hcd)
{
        unsigned long flags;

        dev_err (hcd->self.controller, "HC died; cleaning up\n");

        spin_lock_irqsave (&hcd_root_hub_lock, flags);
        if (hcd->rh_registered) {
                hcd->poll_rh = 0;

                /* make khubd clean up old urbs and devices */
                usb_set_device_state (hcd->self.root_hub,
                                USB_STATE_NOTATTACHED);
                usb_kick_khubd (hcd->self.root_hub);
        }
        spin_unlock_irqrestore (&hcd_root_hub_lock, flags);
}
EXPORT_SYMBOL_GPL (usb_hc_died);

/*-------------------------------------------------------------------------*/

/**
 * usb_create_hcd - create and initialize an HCD structure
 * @driver: HC driver that will use this hcd
 * @dev: device for this HC, stored in hcd->self.controller
 * @bus_name: value to store in hcd->self.bus_name
 * Context: !in_interrupt()
 *
 * Allocate a struct usb_hcd, with extra space at the end for the
 * HC driver's private data.  Initialize the generic members of the
 * hcd structure.
 *
 * If memory is unavailable, returns NULL.
 */
struct usb_hcd *usb_create_hcd (const struct hc_driver *driver,
                struct device *dev, char *bus_name)
{
        struct usb_hcd *hcd;

        hcd = kzalloc(sizeof(*hcd) + driver->hcd_priv_size, GFP_KERNEL);
        if (!hcd) {
                dev_dbg (dev, "hcd alloc failed\n");
                return NULL;
        }
        dev_set_drvdata(dev, hcd);
        kref_init(&hcd->kref);

        usb_bus_init(&hcd->self);
        hcd->self.controller = dev;
        hcd->self.bus_name = bus_name;
        hcd->self.uses_dma = (dev->dma_mask != NULL);

        init_timer(&hcd->rh_timer);
        hcd->rh_timer.function = rh_timer_func;
        hcd->rh_timer.data = (unsigned long) hcd;

        hcd->driver = driver;
        hcd->product_desc = (driver->product_desc) ? driver->product_desc :
                        "USB Host Controller";

        return hcd;
}
EXPORT_SYMBOL (usb_create_hcd);

static void hcd_release (struct kref *kref)
{
        struct usb_hcd *hcd = container_of (kref, struct usb_hcd, kref);

        kfree(hcd);
}

struct usb_hcd *usb_get_hcd (struct usb_hcd *hcd)
{
        if (hcd)
                kref_get (&hcd->kref);
        return hcd;
}
EXPORT_SYMBOL (usb_get_hcd);

void usb_put_hcd (struct usb_hcd *hcd)
{
        if (hcd)
                kref_put (&hcd->kref, hcd_release);
}
EXPORT_SYMBOL (usb_put_hcd);

/**
 * usb_add_hcd - finish generic HCD structure initialization and register
 * @hcd: the usb_hcd structure to initialize
 * @irqnum: Interrupt line to allocate
 * @irqflags: Interrupt type flags
 *
 * Finish the remaining parts of generic HCD initialization: allocate the
 * buffers of consistent memory, register the bus, request the IRQ line,
 * and call the driver's reset() and start() routines.
 */
int usb_add_hcd(struct usb_hcd *hcd,
                unsigned int irqnum, unsigned long irqflags)
{
        int retval;
        struct usb_device *rhdev;

        dev_info(hcd->self.controller, "%s\n", hcd->product_desc);

        set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);

        /* HC is in reset state, but accessible.  Now do the one-time init,
         * bottom up so that hcds can customize the root hubs before khubd
         * starts talking to them.  (Note, bus id is assigned early too.)
         */
        if ((retval = hcd_buffer_create(hcd)) != 0) {
                dev_dbg(hcd->self.controller, "pool alloc failed\n");
                return retval;
        }

        if ((retval = usb_register_bus(&hcd->self)) < 0)
                goto err_register_bus;

        if ((rhdev = usb_alloc_dev(NULL, &hcd->self, 0)) == NULL) {
                dev_err(hcd->self.controller, "unable to allocate root hub\n");
                retval = -ENOMEM;
                goto err_allocate_root_hub;
        }
        rhdev->speed = (hcd->driver->flags & HCD_USB2) ? USB_SPEED_HIGH :
                        USB_SPEED_FULL;
        hcd->self.root_hub = rhdev;

        /* wakeup flag init defaults to "everything works" for root hubs,
         * but drivers can override it in reset() if needed, along with
         * recording the overall controller's system wakeup capability.
         */
        device_init_wakeup(&rhdev->dev, 1);

        /* "reset" is misnamed; its role is now one-time init. the controller
         * should already have been reset (and boot firmware kicked off etc).
         */
        if (hcd->driver->reset && (retval = hcd->driver->reset(hcd)) < 0) {
                dev_err(hcd->self.controller, "can't setup\n");
                goto err_hcd_driver_setup;
        }

        /* NOTE: root hub and controller capabilities may not be the same */
        if (device_can_wakeup(hcd->self.controller)
                        && device_can_wakeup(&hcd->self.root_hub->dev))
                dev_dbg(hcd->self.controller, "supports USB remote wakeup\n");

        /* enable irqs just before we start the controller */
        if (hcd->driver->irq) {
                snprintf(hcd->irq_descr, sizeof(hcd->irq_descr), "%s:usb%d",
                                hcd->driver->description, hcd->self.busnum);
                if ((retval = request_irq(irqnum, &usb_hcd_irq, irqflags,
                                hcd->irq_descr, hcd)) != 0) {
                        dev_err(hcd->self.controller,
                                        "request interrupt %d failed\n", irqnum);
                        goto err_request_irq;
                }
                hcd->irq = irqnum;
                dev_info(hcd->self.controller, "irq %d, %s 0x%08llx\n", irqnum,
                                (hcd->driver->flags & HCD_MEMORY) ?
                                        "io mem" : "io base",
                                        (unsigned long long)hcd->rsrc_start);
        } else {
                hcd->irq = -1;
                if (hcd->rsrc_start)
                        dev_info(hcd->self.controller, "%s 0x%08llx\n",
                                        (hcd->driver->flags & HCD_MEMORY) ?
                                        "io mem" : "io base",
                                        (unsigned long long)hcd->rsrc_start);
        }

        if ((retval = hcd->driver->start(hcd)) < 0) {
                dev_err(hcd->self.controller, "startup error %d\n", retval);
                goto err_hcd_driver_start;
        }

        /* starting here, usbcore will pay attention to this root hub */
        rhdev->bus_mA = min(500u, hcd->power_budget);
        if ((retval = register_root_hub(hcd)) != 0)
                goto err_register_root_hub;

        if (hcd->uses_new_polling && hcd->poll_rh)
                usb_hcd_poll_rh_status(hcd);
        return retval;

err_register_root_hub:
        hcd->driver->stop(hcd);
err_hcd_driver_start:
        if (hcd->irq >= 0)
                free_irq(irqnum, hcd);
err_request_irq:
err_hcd_driver_setup:
        hcd->self.root_hub = NULL;
        usb_put_dev(rhdev);
err_allocate_root_hub:
        usb_deregister_bus(&hcd->self);
err_register_bus:
        hcd_buffer_destroy(hcd);
        return retval;
} 
EXPORT_SYMBOL (usb_add_hcd);

/**
 * usb_remove_hcd - shutdown processing for generic HCDs
 * @hcd: the usb_hcd structure to remove
 * Context: !in_interrupt()
 *
 * Disconnects the root hub, then reverses the effects of usb_add_hcd(),
 * invoking the HCD's stop() method.
 */
void usb_remove_hcd(struct usb_hcd *hcd)
{
        dev_info(hcd->self.controller, "remove, state %x\n", hcd->state);

        if (HC_IS_RUNNING (hcd->state))
                hcd->state = HC_STATE_QUIESCING;

        dev_dbg(hcd->self.controller, "roothub graceful disconnect\n");
        spin_lock_irq (&hcd_root_hub_lock);
        hcd->rh_registered = 0;
        spin_unlock_irq (&hcd_root_hub_lock);

        mutex_lock(&usb_bus_list_lock);
        usb_disconnect(&hcd->self.root_hub);
        mutex_unlock(&usb_bus_list_lock);

        hcd->driver->stop(hcd);
        hcd->state = HC_STATE_HALT;

        hcd->poll_rh = 0;
        del_timer_sync(&hcd->rh_timer);

        if (hcd->irq >= 0)
                free_irq(hcd->irq, hcd);
        usb_deregister_bus(&hcd->self);
        hcd_buffer_destroy(hcd);
}
EXPORT_SYMBOL (usb_remove_hcd);

void
usb_hcd_platform_shutdown(struct platform_device* dev)
{
        struct usb_hcd *hcd = platform_get_drvdata(dev);

        if (hcd->driver->shutdown)
                hcd->driver->shutdown(hcd);
}
EXPORT_SYMBOL (usb_hcd_platform_shutdown);

/*-------------------------------------------------------------------------*/

#if defined(CONFIG_USB_MON)

struct usb_mon_operations *mon_ops;

/*
 * The registration is unlocked.
 * We do it this way because we do not want to lock in hot paths.
 *
 * Notice that the code is minimally error-proof. Because usbmon needs
 * symbols from usbcore, usbcore gets referenced and cannot be unloaded first.
 */
 
int usb_mon_register (struct usb_mon_operations *ops)
{

        if (mon_ops)
                return -EBUSY;

        mon_ops = ops;
        mb();
        return 0;
}
EXPORT_SYMBOL_GPL (usb_mon_register);

void usb_mon_deregister (void)
{

        if (mon_ops == NULL) {
                printk(KERN_ERR "USB: monitor was not registered\n");
                return;
        }
        mon_ops = NULL;
        mb();
}
EXPORT_SYMBOL_GPL (usb_mon_deregister);

#endif /* CONFIG_USB_MON */