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[linux-2.6.9-moxart.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/config.h>

#ifdef CONFIG_USB_DEBUG
#define DEBUG
#endif

#include <linux/module.h>
#include <linux/version.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/completion.h>
#include <linux/uts.h>                  /* for UTS_SYSNAME */
#include <linux/mm.h>
#include <asm/io.h>
#include <asm/scatterlist.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <asm/byteorder.h>

#include <linux/usb.h>

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

//#define VICTOR_DEBUG
#ifdef VICTOR_DEBUG
#define victor_printk(x...)     printk(x)
#else   // VICTOR_DEBUG
#define victor_printk(x...)
#endif  // VICTOR_DEBUG

// #define USB_BANDWIDTH_MESSAGES

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

/*
 * 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 */
DECLARE_MUTEX (usb_bus_list_lock);      /* exported only for usbfs */
EXPORT_SYMBOL_GPL (usb_bus_list_lock);

/* used when updating hcd data */
static spinlock_t hcd_data_lock = SPIN_LOCK_UNLOCKED;

/* 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, /*  __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; */
        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, /*  __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; */
        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, /*  __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)
 * @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) {
                *data++ = 4; *data++ = 3;       /* 4 bytes string data */
                *data++ = 0x09; *data++ = 0x04; /* MSFT-speak for "en-us" */
                return 4;

        // serial number
        } else if (id == 1) {
                strcpy (buf, hcd->self.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;
        u16             typeReq, wValue, wIndex, wLength;
        const u8        *bufp = NULL;
        u8              *ubuf = urb->transfer_buffer;
        int             len = 0;
        int             patch_wakeup = 0;
        unsigned long   flags;

        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;

        /* set up for success */
        urb->status = 0;
        urb->actual_length = wLength;
        switch (typeReq) {

        /* DEVICE REQUESTS */

        case DeviceRequest | USB_REQ_GET_STATUS:
                ubuf [0] = (hcd->remote_wakeup << USB_DEVICE_REMOTE_WAKEUP)
                                | (1 << USB_DEVICE_SELF_POWERED);
                ubuf [1] = 0;
                break;
        case DeviceOutRequest | USB_REQ_CLEAR_FEATURE:
                if (wValue == USB_DEVICE_REMOTE_WAKEUP)
                        hcd->remote_wakeup = 0;
                else
                        goto error;
                break;
        case DeviceOutRequest | USB_REQ_SET_FEATURE:
                if (hcd->can_wakeup && wValue == USB_DEVICE_REMOTE_WAKEUP)
                        hcd->remote_wakeup = 1;
                else
                        goto error;
                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;
                        }
                        if (hcd->can_wakeup)
                                patch_wakeup = 1;
                        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
                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
                ubuf [0] = 0;
                ubuf [1] = 0;
                        /* 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 */
                if (HCD_IS_SUSPENDED (hcd->state))
                        urb->status = -EAGAIN;
                else if (!HCD_IS_RUNNING (hcd->state))
                        urb->status = -ENODEV;
                else
                        urb->status = hcd->driver->hub_control (hcd,
                                typeReq, wValue, wIndex,
                                ubuf, wLength);
                break;
error:
                /* "protocol stall" on error */
                urb->status = -EPIPE;
                dev_dbg (hcd->self.controller, "unsupported hub control message (maxchild %d)\n",
                                urb->dev->maxchild);
        }
        if (urb->status) {
                urb->actual_length = 0;
                dev_dbg (hcd->self.controller, "CTRL: TypeReq=0x%x val=0x%x idx=0x%x len=%d ==> %d\n",
                        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);

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

        /* any errors get returned through the urb completion */
        local_irq_save (flags);
        usb_hcd_giveback_urb (hcd, urb, NULL);
        local_irq_restore (flags);
        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 (hcd->rh_timer.data
                        || urb->status != -EINPROGRESS
                        || urb->transfer_buffer_length < len
                        || !HCD_IS_RUNNING (hcd->state)) {
                dev_dbg (hcd->self.controller,
                                "not queuing rh status urb, stat %d\n",
                                urb->status);
                return -EINVAL;
        }

        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);
        urb->hcpriv = hcd;      /* nonzero to indicate it's queued */
        return 0;
}

/* timer callback */

static void rh_report_status (unsigned long ptr)
{
        struct urb      *urb;
        struct usb_hcd  *hcd;
        int             length = 0;
        unsigned long   flags;

        urb = (struct urb *) ptr;
        local_irq_save (flags);
        spin_lock (&urb->lock);

        /* do nothing if the urb's been unlinked */
        if (!urb->dev
                        || urb->status != -EINPROGRESS
                        || (hcd = urb->dev->bus->hcpriv) == 0) {
                spin_unlock (&urb->lock);
                local_irq_restore (flags);
                return;
        }

        if (!HCD_IS_SUSPENDED (hcd->state))
                length = hcd->driver->hub_status_data (
                                        hcd, urb->transfer_buffer);

        /* complete the status urb, or retrigger the timer */
        spin_lock (&hcd_data_lock);
        if (length > 0) {
                hcd->rh_timer.data = 0;
                urb->actual_length = length;
                urb->status = 0;
                urb->hcpriv = NULL;
        } else
                mod_timer (&hcd->rh_timer, jiffies + HZ/4);
        spin_unlock (&hcd_data_lock);
        spin_unlock (&urb->lock);

        /* local irqs are always blocked in completions */
        if (length > 0)
                usb_hcd_giveback_urb (hcd, urb, NULL);
        local_irq_restore (flags);
}

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

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;
}

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

int usb_rh_status_dequeue (struct usb_hcd *hcd, struct urb *urb)
{
        unsigned long   flags;

        /* note:  always a synchronous unlink */
        del_timer_sync (&hcd->rh_timer);
        hcd->rh_timer.data = 0;

        local_irq_save (flags);
        urb->hcpriv = NULL;
        usb_hcd_giveback_urb (hcd, urb, NULL);
        local_irq_restore (flags);
        return 0;
}

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

/* exported only within usbcore */
struct usb_bus *usb_bus_get (struct usb_bus *bus)
{
        struct class_device *tmp;

        if (!bus)
                return NULL;

        tmp = class_device_get(&bus->class_dev);
        if (tmp)        
                return to_usb_bus(tmp);
        else
                return NULL;
}

/* exported only within usbcore */
void usb_bus_put (struct usb_bus *bus)
{
        if (bus)
                class_device_put(&bus->class_dev);
}

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

static void usb_host_release(struct class_device *class_dev)
{
        struct usb_bus *bus = to_usb_bus(class_dev);

        if (bus->release)
                bus->release(bus);
}

static struct class usb_host_class = {
        .name           = "usb_host",
        .release        = &usb_host_release,
};

int usb_host_init(void)
{
        return class_register(&usb_host_class);
}

void usb_host_cleanup(void)
{
        class_unregister(&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.
 */
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->hcpriv = NULL;
        bus->busnum = -1;
        bus->bandwidth_allocated = 0;
        bus->bandwidth_int_reqs  = 0;
        bus->bandwidth_isoc_reqs = 0;

        INIT_LIST_HEAD (&bus->bus_list);
}
EXPORT_SYMBOL (usb_bus_init);

/**
 * usb_alloc_bus - creates a new USB host controller structure
 * @op: pointer to a struct usb_operations that this bus structure should use
 * Context: !in_interrupt()
 *
 * Creates a USB host controller bus structure with the specified 
 * usb_operations and initializes all the necessary internal objects.
 *
 * If no memory is available, NULL is returned.
 *
 * The caller should call usb_put_bus() when it is finished with the structure.
 */
struct usb_bus *usb_alloc_bus (struct usb_operations *op)
{
        struct usb_bus *bus;

        bus = kmalloc (sizeof *bus, GFP_KERNEL);
        if (!bus)
                return NULL;
        memset(bus, 0, sizeof(struct usb_bus));
        usb_bus_init (bus);
        bus->op = op;
        return bus;
}
EXPORT_SYMBOL (usb_alloc_bus);

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

/**
 * 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.
 */
int usb_register_bus(struct usb_bus *bus)
{
        int busnum;
        int retval;

        down (&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);
                up(&usb_bus_list_lock);
                return -E2BIG;
        }

        snprintf(bus->class_dev.class_id, BUS_ID_SIZE, "usb%d", busnum);
        bus->class_dev.class = &usb_host_class;
        bus->class_dev.dev = bus->controller;
        retval = class_device_register(&bus->class_dev);
        if (retval) {
                clear_bit(busnum, busmap.busmap);
                up(&usb_bus_list_lock);
                return retval;
        }

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

        usbfs_add_bus (bus);

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

/**
 * 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.
 */
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
         */
        down (&usb_bus_list_lock);
        list_del (&bus->bus_list);
        up (&usb_bus_list_lock);

        usbfs_remove_bus (bus);

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

        class_device_unregister(&bus->class_dev);
}
EXPORT_SYMBOL (usb_deregister_bus);

/**
 * usb_register_root_hub - called by HCD to register its root hub 
 * @usb_dev: the usb root hub device to be registered.
 * @parent_dev: the parent device of this root hub.
 *
 * The USB host controller calls this function to register the root hub
 * properly with the USB subsystem.  It sets up the device properly in
 * the device tree and stores the root_hub pointer in the bus structure,
 * then calls usb_new_device() to register the usb device.  It also
 * assigns the root hub's USB address (always 1).
 */
int usb_register_root_hub (struct usb_device *usb_dev, struct device *parent_dev)
{
        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);

        down (&usb_bus_list_lock);
        usb_dev->bus->root_hub = usb_dev;

        usb_dev->epmaxpacketin[0] = usb_dev->epmaxpacketout[0] = 64;
        retval = usb_get_device_descriptor(usb_dev, USB_DT_DEVICE_SIZE);
        if (retval != sizeof usb_dev->descriptor) {
                usb_dev->bus->root_hub = NULL;
                up (&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;
        }

        down (&usb_dev->serialize);
        retval = usb_new_device (usb_dev);
        up (&usb_dev->serialize);
        if (retval) {
                usb_dev->bus->root_hub = NULL;
                dev_err (parent_dev, "can't register root hub for %s, %d\n",
                                usb_dev->dev.bus_id, retval);
        }
        up (&usb_bus_list_lock);
        return retval;
}
EXPORT_SYMBOL (usb_register_root_hub);


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

/**
 * 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_USECS (bytecount);
                else
                        tmp = HS_USECS_ISO (bytecount);
                return tmp;
        default:
                pr_debug ("%s: bogus device speed!\n", usbcore_name);
                return -1;
        }
}
EXPORT_SYMBOL (usb_calc_bus_time);

/*
 * usb_check_bandwidth():
 *
 * old_alloc is from host_controller->bandwidth_allocated in microseconds;
 * bustime is from calc_bus_time(), but converted to microseconds.
 *
 * returns <bustime in us> if successful,
 * or -ENOSPC if bandwidth request fails.
 *
 * FIXME:
 * This initial implementation does not use Endpoint.bInterval
 * in managing bandwidth allocation.
 * It probably needs to be expanded to use Endpoint.bInterval.
 * This can be done as a later enhancement (correction).
 *
 * This will also probably require some kind of
 * frame allocation tracking...meaning, for example,
 * that if multiple drivers request interrupts every 10 USB frames,
 * they don't all have to be allocated at
 * frame numbers N, N+10, N+20, etc.  Some of them could be at
 * N+11, N+21, N+31, etc., and others at
 * N+12, N+22, N+32, etc.
 *
 * Similarly for isochronous transfers...
 *
 * Individual HCDs can schedule more directly ... this logic
 * is not correct for high speed transfers.
 */
int usb_check_bandwidth (struct usb_device *dev, struct urb *urb)
{
        unsigned int    pipe = urb->pipe;
        long            bustime;
        int             is_in = usb_pipein (pipe);
        int             is_iso = usb_pipeisoc (pipe);
        int             old_alloc = dev->bus->bandwidth_allocated;
        int             new_alloc;


        bustime = NS_TO_US (usb_calc_bus_time (dev->speed, is_in, is_iso,
                        usb_maxpacket (dev, pipe, !is_in)));
        if (is_iso)
                bustime /= urb->number_of_packets;

        new_alloc = old_alloc + (int) bustime;
        if (new_alloc > FRAME_TIME_MAX_USECS_ALLOC) {
#ifdef  DEBUG
                char    *mode = 
#ifdef CONFIG_USB_BANDWIDTH
                        "";
#else
                        "would have ";
#endif
                dev_dbg (&dev->dev, "usb_check_bandwidth %sFAILED: %d + %ld = %d usec\n",
                        mode, old_alloc, bustime, new_alloc);
#endif
#ifdef CONFIG_USB_BANDWIDTH
                bustime = -ENOSPC;      /* report error */
#endif
        }

        return bustime;
}
EXPORT_SYMBOL (usb_check_bandwidth);


/**
 * usb_claim_bandwidth - records bandwidth for a periodic transfer
 * @dev: source/target of request
 * @urb: request (urb->dev == dev)
 * @bustime: bandwidth consumed, in (average) microseconds per frame
 * @isoc: true iff the request is isochronous
 *
 * Bus bandwidth reservations are recorded purely for diagnostic purposes.
 * HCDs are expected not to overcommit periodic bandwidth, and to record such
 * reservations whenever endpoints are added to the periodic schedule.
 *
 * FIXME averaging per-frame is suboptimal.  Better to sum over the HCD's
 * entire periodic schedule ... 32 frames for OHCI, 1024 for UHCI, settable
 * for EHCI (256/512/1024 frames, default 1024) and have the bus expose how
 * large its periodic schedule is.
 */
void usb_claim_bandwidth (struct usb_device *dev, struct urb *urb, int bustime, int isoc)
{
        dev->bus->bandwidth_allocated += bustime;
        if (isoc)
                dev->bus->bandwidth_isoc_reqs++;
        else
                dev->bus->bandwidth_int_reqs++;
        urb->bandwidth = bustime;

#ifdef USB_BANDWIDTH_MESSAGES
        dev_dbg (&dev->dev, "bandwidth alloc increased by %d (%s) to %d for %d requesters\n",
                bustime,
                isoc ? "ISOC" : "INTR",
                dev->bus->bandwidth_allocated,
                dev->bus->bandwidth_int_reqs + dev->bus->bandwidth_isoc_reqs);
#endif
}
EXPORT_SYMBOL (usb_claim_bandwidth);


/**
 * usb_release_bandwidth - reverses effect of usb_claim_bandwidth()
 * @dev: source/target of request
 * @urb: request (urb->dev == dev)
 * @isoc: true iff the request is isochronous
 *
 * This records that previously allocated bandwidth has been released.
 * Bandwidth is released when endpoints are removed from the host controller's
 * periodic schedule.
 */
void usb_release_bandwidth (struct usb_device *dev, struct urb *urb, int isoc)
{
        dev->bus->bandwidth_allocated -= urb->bandwidth;
        if (isoc)
                dev->bus->bandwidth_isoc_reqs--;
        else
                dev->bus->bandwidth_int_reqs--;

#ifdef USB_BANDWIDTH_MESSAGES
        dev_dbg (&dev->dev, "bandwidth alloc reduced by %d (%s) to %d for %d requesters\n",
                urb->bandwidth,
                isoc ? "ISOC" : "INTR",
                dev->bus->bandwidth_allocated,
                dev->bus->bandwidth_int_reqs + dev->bus->bandwidth_isoc_reqs);
#endif
        urb->bandwidth = 0;
}
EXPORT_SYMBOL (usb_release_bandwidth);


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

/*
 * 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 urb_unlink (struct urb *urb)
{
        unsigned long           flags;

        /* 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);
        spin_unlock_irqrestore (&hcd_data_lock, flags);
        usb_put_dev (urb->dev);
}


/* 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
 */
static int hcd_submit_urb (struct urb *urb, int mem_flags)
{
        int                     status;
        struct usb_hcd          *hcd = urb->dev->bus->hcpriv;
        struct hcd_dev          *dev = urb->dev->hcpriv;
        unsigned long           flags;

        if (!hcd || !dev)
                return -ENODEV;

        /*
         * 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 (unlikely (urb->reject))
                status = -EPERM;
        else if (HCD_IS_RUNNING (hcd->state) &&
                        hcd->state != USB_STATE_QUIESCING) {
                usb_get_dev (urb->dev);
                list_add_tail (&urb->urb_list, &dev->urb_list);
                status = 0;
        } else
                status = -ESHUTDOWN;
        spin_unlock_irqrestore (&hcd_data_lock, flags);
        if (status) {
                INIT_LIST_HEAD (&urb->urb_list);
                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.
                 */
                urb->transfer_flags |= (URB_NO_TRANSFER_DMA_MAP
                                        | URB_NO_SETUP_DMA_MAP);
                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.controller->dma_mask) {
                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, 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);
        }
        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;
        if (!HCD_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 == (struct urb *) hcd->rh_timer.data)
                value = usb_rh_status_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
 */
static int hcd_unlink_urb (struct urb *urb, int status)
{
        struct hcd_dev                  *dev;
        struct usb_hcd                  *hcd = NULL;
        struct device                   *sys = NULL;
        unsigned long                   flags;
        struct list_head                *tmp;
        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->dev || !urb->dev->bus) {
                retval = -ENODEV;
                goto done;
        }

        dev = urb->dev->hcpriv;
        sys = &urb->dev->dev;
        hcd = urb->dev->bus->hcpriv;
        if (!dev || !hcd) {
                retval = -ENODEV;
                goto done;
        }

        /* running ~= hc unlink handshake works (irq, timer, etc)
         * halted ~= no unlink handshake is needed
         * suspended, resuming == should never happen
         */
        WARN_ON (!HCD_IS_RUNNING (hcd->state) && hcd->state != USB_STATE_HALT);

        /* insist the urb is still queued */
        list_for_each(tmp, &dev->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;
        }

        /* PCI 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().
         */
        if (!hcd->saw_irq) {
                dev_warn (hcd->self.controller, "Unlink after no-IRQ?  "
                        "Different ACPI or APIC settings may help."
                        "\n");
                hcd->saw_irq = 1;
        }

        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. use for
 * set_configuration, set_interface, driver removal, physical disconnect.
 *
 * example:  a qh stored in hcd_dev.ep[], holding state related to endpoint
 * type, maxpacket size, toggle, halt status, and scheduling.
 */
static void hcd_endpoint_disable (struct usb_device *udev, int endpoint)
{
        struct hcd_dev  *dev;
        struct usb_hcd  *hcd;
        struct urb      *urb;
        unsigned        epnum = endpoint & USB_ENDPOINT_NUMBER_MASK;

        dev = udev->hcpriv;
        hcd = udev->bus->hcpriv;

        WARN_ON (!HCD_IS_RUNNING (hcd->state) && hcd->state != USB_STATE_HALT);

        local_irq_disable ();

rescan:
        /* (re)block new requests, as best we can */
        if (endpoint & USB_DIR_IN)
                udev->epmaxpacketin [epnum] = 0;
        else
                udev->epmaxpacketout [epnum] = 0;

        /* then kill any current requests */
        spin_lock (&hcd_data_lock);
        list_for_each_entry (urb, &dev->urb_list, urb_list) {
                int     tmp = urb->pipe;

                /* ignore urbs for other endpoints */
                if (usb_pipeendpoint (tmp) != epnum)
                        continue;
                /* NOTE assumption that only ep0 is a control endpoint */
                if (epnum != 0 && ((tmp ^ endpoint) & USB_DIR_IN))
                        continue;

                /* another cpu may be in hcd, spinning on hcd_data_lock
                 * to giveback() this urb.  the races here should be
                 * small, but a full fix needs a new "can't submit"
                 * urb state.
                 */
                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, dev, endpoint);
}

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

#ifdef  CONFIG_USB_SUSPEND

static int hcd_hub_suspend (struct usb_bus *bus)
{
        struct usb_hcd          *hcd;

        hcd = container_of (bus, struct usb_hcd, self);
        if (hcd->driver->hub_suspend)
                return hcd->driver->hub_suspend (hcd);
        return 0;
}

static int hcd_hub_resume (struct usb_bus *bus)
{
        struct usb_hcd          *hcd;

        hcd = container_of (bus, struct usb_hcd, self);
        if (hcd->driver->hub_resume)
                return hcd->driver->hub_resume (hcd);
        return 0;
}

#endif

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

#ifdef  CONFIG_USB_OTG

/**
 * usb_bus_start_enum - start immediate enumeration (for OTG)
 * @bus: the bus (must use hcd framework)
 * @port: 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

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

/* called by khubd, rmmod, apmd, or other thread for hcd-private cleanup.
 * we're guaranteed that the device is fully quiesced.  also, that each
 * endpoint has been hcd_endpoint_disabled.
 */

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)) {
                dev_dbg (hcd->self.controller, "free busy dev, %s devnum %d (bug!)\n",
                        hcd->self.bus_name, udev->devnum);
                return -EINVAL;
        }

        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;
}

/*
 * usb_hcd_operations - adapts usb_bus framework to HCD framework (bus glue)
 *
 * When registering a USB bus through the HCD framework code, use this
 * usb_operations vector.  The PCI glue layer does so automatically; only
 * bus glue for non-PCI system busses will need to use this.
 */
struct usb_operations usb_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,
        .buffer_alloc =         hcd_buffer_alloc,
        .buffer_free =          hcd_buffer_free,
        .disable =              hcd_endpoint_disable,
#ifdef  CONFIG_USB_SUSPEND
        .hub_suspend =          hcd_hub_suspend,
        .hub_resume =           hcd_hub_resume,
#endif
};
EXPORT_SYMBOL (usb_hcd_operations);

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

/**
 * 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: pt_regs, passed down to the URB completion handler
 * 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, struct pt_regs *regs)
{
        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.

        /* lower level hcd code should use *_dma exclusively */
        if (hcd->self.controller->dma_mask) {
                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);
        }

        /* pass ownership to the completion handler */
        urb->complete (urb, regs);
        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 beinng signaled
 * @r: saved hardware registers
 *
 * When registering a USB bus through the HCD framework code, use this
 * to handle interrupts.  The PCI glue layer does so automatically; only
 * bus glue for non-PCI system busses will need to use this.
 */
irqreturn_t usb_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 IRQ_NONE;

        hcd->saw_irq = 1;
        if (hcd->driver->irq (hcd, r) == IRQ_NONE)
                return IRQ_NONE;

        if (hcd->state != start && hcd->state == USB_STATE_HALT) {
                usb_hc_died (hcd);
        }
        return IRQ_HANDLED;
}
EXPORT_SYMBOL (usb_hcd_irq);

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

static void hcd_panic (void *_hcd)
{
        struct usb_hcd          *hcd = _hcd;
        struct usb_device       *hub = hcd->self.root_hub;
        unsigned                i;

        /* hc's root hub is removed later removed in hcd->stop() */
        down (&hub->serialize);
        usb_set_device_state(hub, USB_STATE_NOTATTACHED);
        for (i = 0; i < hub->maxchild; i++) {
                if (hub->children [i])
                        usb_disconnect (&hub->children [i]);
        }
        up (&hub->serialize);
}

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

        /* clean up old urbs and devices; needs a task context */
        INIT_WORK (&hcd->work, hcd_panic, hcd);
        (void) schedule_work (&hcd->work);
}
EXPORT_SYMBOL (usb_hc_died);