Import 2.3.1pre2

[davej-history.git] / drivers / usb / uhci.c

/*
 * Universal Host Controller Interface driver for USB.
 *
 * (C) Copyright 1999 Linus Torvalds
 *
 * Intel documents this fairly well, and as far as I know there
 * are no royalties or anything like that, but even so there are
 * people who decided that they want to do the same thing in a
 * completely different way.
 *
 * Oh, well. The intel version is the more common by far. As such,
 * that's the one I care about right now.
 *
 * WARNING! The USB documentation is downright evil. Most of it
 * is just crap, written by a committee. You're better off ignoring
 * most of it, the important stuff is:
 *  - the low-level protocol (fairly simple but lots of small details)
 *  - working around the horridness of the rest
 */

/* 4/4/1999 added data toggle for interrupt pipes -keryan */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/sched.h>
#include <linux/malloc.h>
#include <linux/smp_lock.h>
#include <linux/errno.h>

#include <asm/spinlock.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/system.h>

#include "uhci.h"
#include "inits.h"

#ifdef CONFIG_APM
#include <linux/apm_bios.h>
static int handle_apm_event(apm_event_t event);
static int apm_resume = 0;
#endif

#define compile_assert(x) do { switch (0) { case 1: case !(x): } } while (0)

static DECLARE_WAIT_QUEUE_HEAD(uhci_configure);

/*
 * Return the result of a TD..
 */
static int uhci_td_result(struct uhci_device *dev, struct uhci_td *td)
{
        unsigned int status;

        status = (td->status >> 16) & 0xff;

        /* Some debugging code */
        if (status) {
                int i = 10;
                struct uhci_td *tmp = dev->control_td;
                printk("uhci_td_result() failed with status %d\n", status);
                show_status(dev->uhci);
                do {
                        show_td(tmp);
                        tmp++;
                        if (!--i)
                                break;
                } while (tmp <= td);
        }
        return status;          
}

/*
 * Inserts a td into qh list at the top.
 *
 * Careful about atomicity: even on UP this
 * requires a locked access due to the concurrent
 * DMA engine.
 *
 * NOTE! This assumes that first->last is a valid
 * list of TD's with the proper backpointers set
 * up and all..
 */
static void uhci_insert_tds_in_qh(struct uhci_qh *qh, struct uhci_td *first, struct uhci_td *last)
{
        unsigned int link = qh->element;
        unsigned int new = 4 | virt_to_bus(first);

        for (;;) {
                unsigned char success;

                last->link = link;
                first->backptr = &qh->element;
                asm volatile("lock ; cmpxchg %4,%2 ; sete %0"
                        :"=q" (success), "=a" (link)
                        :"m" (qh->element), "1" (link), "r" (new)
                        :"memory");
                if (success) {
                        /* Was there a successor entry? Fix it's backpointer.. */
                        if ((link & 1) == 0) {
                                struct uhci_td *next = bus_to_virt(link & ~15);
                                next->backptr = &last->link;
                        }
                        break;
                }
        }
}

static inline void uhci_insert_td_in_qh(struct uhci_qh *qh, struct uhci_td *td)
{
        uhci_insert_tds_in_qh(qh, td, td);
}

static void uhci_insert_qh(struct uhci_qh *qh, struct uhci_qh *newqh)
{
        newqh->link = qh->link;
        qh->link = virt_to_bus(newqh) | 2;
}

static void uhci_remove_qh(struct uhci_qh *qh, struct uhci_qh *remqh)
{
        unsigned int remphys = virt_to_bus(remqh);
        struct uhci_qh *lqh = qh;

        while ((lqh->link & ~0xF) != remphys) {
                if (lqh->link & 1)
                        break;

                lqh = bus_to_virt(lqh->link & ~0xF);
        }

        if (lqh->link & 1) {
                printk("couldn't find qh in chain!\n");
                return;
        }

        lqh->link = remqh->link;
}

/*
 * Removes td from qh if present.
 *
 * NOTE! We keep track of both forward and back-pointers,
 * so this should be trivial, right?
 *
 * Wrong. While all TD insert/remove operations are synchronous
 * on the CPU, the UHCI controller can (and does) play with the
 * very first forward pointer. So we need to validate the backptr
 * before we change it, so that we don't by mistake reset the QH
 * head to something old.
 */
static void uhci_remove_td(struct uhci_td *td)
{
        unsigned int *backptr = td->backptr;
        unsigned int link = td->link;
        unsigned int me;

        if (!backptr)
                return;

        td->backptr = NULL;

        /*
         * This is the easy case: the UHCI will never change "td->link",
         * so we can always just look at that and fix up the backpointer
         * of any next element..
         */
        if (!(link & 1)) {
                struct uhci_td *next = bus_to_virt(link & ~15);
                next->backptr = backptr;
        }

        /*
         * The nasty case is "backptr->next", which we need to
         * update to "link" _only_ if "backptr" still points
         * to us (it may not: maybe backptr is a QH->element
         * pointer and the UHCI has changed the value).
         */
        me = virt_to_bus(td) | (0xe & *backptr);
        asm volatile("lock ; cmpxchg %0,%1"
                :
                :"r" (link), "m" (*backptr), "a" (me)
                :"memory");
}

static struct uhci_qh *uhci_qh_allocate(struct uhci_device *dev)
{
        struct uhci_qh *qh;
        int inuse;

        qh = dev->qh;
        for (; (inuse = test_and_set_bit(0, &qh->inuse)) != 0 && qh < &dev->qh[UHCI_MAXQH]; qh++)
                ;

        if (!inuse)
                return(qh);

        printk("ran out of qh's for dev %p\n", dev);
        return(NULL);
}

static void uhci_qh_deallocate(struct uhci_qh *qh)
{
        if (qh->element != 1)
                printk("qh %p leaving dangling entries? (%X)\n", qh, qh->element);

        qh->element = 1;
        qh->link = 1;

        clear_bit(0, &qh->inuse);
}

static struct uhci_td *uhci_td_allocate(struct uhci_device *dev)
{
        struct uhci_td *td;
        int inuse;

        td = dev->td;
        for (; (inuse = test_and_set_bit(0, &td->inuse)) != 0 && td < &dev->td[UHCI_MAXTD]; td++)
                ;

        if (!inuse)
                return(td);

        printk("ran out of td's for dev %p\n", dev);
        return(NULL);
}

/*
 * This MUST only be called when it has been removed from a QH already (or
 * the QH has been removed from the skeleton
 */
static void uhci_td_deallocate(struct uhci_td *td)
{
        td->link = 1;

        clear_bit(0, &td->inuse);
}

/*
 * UHCI interrupt list operations..
 */
static spinlock_t irqlist_lock = SPIN_LOCK_UNLOCKED;

static void uhci_add_irq_list(struct uhci *uhci, struct uhci_td *td, usb_device_irq completed, void *dev_id)
{
        unsigned long flags;

        td->completed = completed;
        td->dev_id = dev_id;

        spin_lock_irqsave(&irqlist_lock, flags);
        list_add(&td->irq_list, &uhci->interrupt_list);
        spin_unlock_irqrestore(&irqlist_lock, flags);
}

static void uhci_remove_irq_list(struct uhci_td *td)
{
        unsigned long flags;

        spin_lock_irqsave(&irqlist_lock, flags);
        list_del(&td->irq_list);
        spin_unlock_irqrestore(&irqlist_lock, flags);
}

/*
 * Request a interrupt handler..
 */
static int uhci_request_irq(struct usb_device *usb_dev, unsigned int pipe, usb_device_irq handler, int period, void *dev_id)
{
        struct uhci_device *dev = usb_to_uhci(usb_dev);
        struct uhci_td *td = uhci_td_allocate(dev);
        struct uhci_qh *interrupt_qh = uhci_qh_allocate(dev);

        unsigned int destination, status;

        /* Destination: pipe destination with INPUT */
        destination = (pipe & 0x0007ff00)  |  0x69;

        /* Status:    slow/fast,      Interrupt,   Active,    Short Packet Detect     Infinite Errors */
        status = (pipe & (1 << 26)) | (1 << 24) | (1 << 23)   |   (1 << 29)       |    (0 << 27);

        if(interrupt_qh->element != 1)
                printk("interrupt_qh->element = 0x%x\n", 
                       interrupt_qh->element);

        td->link = 1;
        td->status = status;                    /* In */
        td->info = destination | (7 << 21);     /* 8 bytes of data */
        td->buffer = virt_to_bus(dev->data);
        td->qh = interrupt_qh;
        interrupt_qh->skel = &dev->uhci->root_hub->skel_int8_qh;

        uhci_add_irq_list(dev->uhci, td, handler, dev_id);

        uhci_insert_td_in_qh(interrupt_qh, td);

        /* Add it into the skeleton */
        uhci_insert_qh(&dev->uhci->root_hub->skel_int8_qh, interrupt_qh);
        return 0;
}

/*
 * Control thread operations: we just mark the last TD
 * in a control thread as an interrupt TD, and wake up
 * the front-end on completion.
 *
 * We need to remove the TD from the lists (both interrupt
 * list and TD lists) by hand if something bad happens!
 */
static DECLARE_WAIT_QUEUE_HEAD(control_wakeup);

static int uhci_control_completed(int status, void *buffer, void *dev_id)
{
        wake_up(&control_wakeup);
        return 0;                       /* Don't re-instate */
}

/* td points to the last td in the list, which interrupts on completion */
static int uhci_run_control(struct uhci_device *dev, struct uhci_td *first, struct uhci_td *last)
{
        DECLARE_WAITQUEUE(wait, current);
        struct uhci_qh *ctrl_qh = uhci_qh_allocate(dev);
        struct uhci_td *curtd;

        current->state = TASK_UNINTERRUPTIBLE;
        add_wait_queue(&control_wakeup, &wait);

        uhci_add_irq_list(dev->uhci, last, uhci_control_completed, NULL);
        
        /* FIXME: This is kinda kludged */
        /* Walk the TD list and update the QH pointer */
        {
        int maxcount = 100;

        curtd = first;
        do {
                curtd->qh = ctrl_qh;
                if (curtd->link & 1)
                        break;

                curtd = bus_to_virt(curtd->link & ~0xF);
                if (!--maxcount) {
                        printk("runaway tds!\n");
                        break;
                }
        } while (1);
        }

        uhci_insert_tds_in_qh(ctrl_qh, first, last);

        /* Add it into the skeleton */
        uhci_insert_qh(&dev->uhci->root_hub->skel_control_qh, ctrl_qh);

        schedule_timeout(HZ/10);

        remove_wait_queue(&control_wakeup, &wait);

        /* Clean up in case it failed.. */
        uhci_remove_irq_list(last);

#if 0
        printk("Looking for tds [%p, %p]\n", dev->control_td, td);
#endif

        /* Remove it from the skeleton */
        uhci_remove_qh(&dev->uhci->root_hub->skel_control_qh, ctrl_qh);

        uhci_qh_deallocate(ctrl_qh);

        return uhci_td_result(dev, last);
}

/*
 * Send or receive a control message on a pipe.
 *
 * Note that the "pipe" structure is set up to map
 * easily to the uhci destination fields.
 *
 * A control message is built up from three parts:
 *  - The command itself
 *  - [ optional ] data phase
 *  - Status complete phase
 *
 * The data phase can be an arbitrary number of TD's
 * although we currently had better not have more than
 * 29 TD's here (we have 31 TD's allocated for control
 * operations, and two of them are used for command and
 * status).
 *
 * 29 TD's is a minimum of 232 bytes worth of control
 * information, that's just ridiculously high. Most
 * control messages have just a few bytes of data.
 */
static int uhci_control_msg(struct usb_device *usb_dev, unsigned int pipe, void *cmd, void *data, int len)
{
        struct uhci_device *dev = usb_to_uhci(usb_dev);
        struct uhci_td *first, *td, *prevtd;
        unsigned long destination, status;
        int ret;

        if (len > usb_maxpacket(usb_dev->maxpacketsize) * 29)
                printk("Warning, too much data for a control packet, crashing\n");

        first = td = uhci_td_allocate(dev);

        /* The "pipe" thing contains the destination in bits 8--18, 0x2D is SETUP */
        destination = (pipe & 0x0007ff00) | 0x2D;

        /* Status:    slow/fast,       Active,    Short Packet Detect     Three Errors */
        status = (pipe & (1 << 26)) | (1 << 23)   |   (1 << 29)       |    (3 << 27);

        /*
         * Build the TD for the control request
         */
        td->status = status;                            /* Try forever */
        td->info = destination | (7 << 21);             /* 8 bytes of data */
        td->buffer = virt_to_bus(cmd);

        /*
         * If direction is "send", change the frame from SETUP (0x2D)
         * to OUT (0xE1). Else change it from SETUP to IN (0x69)
         */
        destination ^= (0x2D ^ 0x69);                   /* SETUP -> IN */
        if (usb_pipeout(pipe))
                destination ^= (0xE1 ^ 0x69);           /* IN -> OUT */

        prevtd = td;
        td = uhci_td_allocate(dev);
        prevtd->link = 4 | virt_to_bus(td);

        /*
         * Build the DATA TD's
         */
        while (len > 0) {
                /* Build the TD for control status */
                int pktsze = len;
                int maxsze = usb_maxpacket(pipe);

                if (pktsze > maxsze)
                        pktsze = maxsze;

                /* Alternate Data0/1 (start with Data1) */
                destination ^= 1 << 19;
        
                td->status = status;                                    /* Status */
                td->info = destination | ((pktsze-1) << 21);            /* pktsze bytes of data */
                td->buffer = virt_to_bus(data);
                td->backptr = &prevtd->link;

                prevtd = td;
                td = uhci_td_allocate(dev);
                prevtd->link = 4 | virt_to_bus(td);                     /* Update previous TD */

                data += maxsze;
                len -= maxsze;
        }

        /*
         * Build the final TD for control status
         */
        destination ^= (0xE1 ^ 0x69);                   /* OUT -> IN */
        destination |= 1 << 19;                         /* End in Data1 */

        td->link = 1;                                   /* Terminate */
        td->status = status | (1 << 24);                /* IOC */
        td->info = destination | (0x7ff << 21);         /* 0 bytes of data */
        td->buffer = 0;
        td->backptr = &prevtd->link;

        /* Start it up.. */
        ret = uhci_run_control(dev, first, td);

        {
                int maxcount = 100;
                struct uhci_td *curtd = first;
                unsigned int nextlink;

                do {
                        nextlink = curtd->link;
                        uhci_remove_td(curtd);
                        uhci_td_deallocate(curtd);
                        if (nextlink & 1)       /* Tail? */
                                break;

                        curtd = bus_to_virt(nextlink & ~0xF);
                        if (!--maxcount) {
                                printk("runaway td's!?\n");
                                break;
                        }
                } while (1);
        }

        return ret;
}

static struct usb_device *uhci_usb_allocate(struct usb_device *parent)
{
        struct usb_device *usb_dev;
        struct uhci_device *dev;
        int i;

        usb_dev = kmalloc(sizeof(*usb_dev), GFP_KERNEL);
        if (!usb_dev)
                return NULL;

        memset(usb_dev, 0, sizeof(*usb_dev));

        dev = kmalloc(sizeof(*dev), GFP_KERNEL);
        if (!dev) {
                usb_destroy_configuration(usb_dev);
                kfree(usb_dev);
                return NULL;
        }

        /* Initialize "dev" */
        memset(dev, 0, sizeof(*dev));

        usb_dev->hcpriv = dev;
        dev->usb = usb_dev;

        usb_dev->parent = parent;

        if (parent) {
                usb_dev->bus = parent->bus;
                dev->uhci = usb_to_uhci(parent)->uhci;
        }

        /* Reset the QH's and TD's */
        for (i = 0; i < UHCI_MAXQH; i++) {
                dev->qh[i].link = 1;
                dev->qh[i].element = 1;
                dev->qh[i].inuse = 0;
        }

        for (i = 0; i < UHCI_MAXTD; i++) {
                dev->td[i].link = 1;
                dev->td[i].inuse = 0;
        }

        return usb_dev;
}

static int uhci_usb_deallocate(struct usb_device *usb_dev)
{
        struct uhci_device *dev = usb_to_uhci(usb_dev);
        int i;

        /* There are UHCI_MAXTD preallocated tds */
        for (i = 0; i < UHCI_MAXTD; ++i) {
                struct uhci_td *td = dev->td + i;

                /* And remove it from the irq list, if it's active */
                if (td->status & (1 << 23))
                        uhci_remove_irq_list(td);

                if (td->inuse)
                        uhci_remove_td(td);
        }

        /* Remove the td from any queues */
        for (i = 0; i < UHCI_MAXQH; ++i) {
                struct uhci_qh *qh = dev->qh + i;

                if (qh->inuse)
                        uhci_remove_qh(qh->skel, qh);
        }

        kfree(dev);
        usb_destroy_configuration(usb_dev);
        kfree(usb_dev);

        return 0;
}

struct usb_operations uhci_device_operations = {
        uhci_usb_allocate,
        uhci_usb_deallocate,
        uhci_control_msg,
        uhci_request_irq,
};

/*
 * This is just incredibly fragile. The timings must be just
 * right, and they aren't really documented very well.
 *
 * Note the short delay between disabling reset and enabling
 * the port..
 */
static void uhci_reset_port(unsigned int port)
{
        unsigned short status;

        status = inw(port);
        outw(status | USBPORTSC_PR, port);              /* reset port */
        wait_ms(10);
        outw(status & ~USBPORTSC_PR, port);
        udelay(5);

        status = inw(port);
        outw(status | USBPORTSC_PE, port);              /* enable port */
        wait_ms(10);

        status = inw(port);
        if(!(status & USBPORTSC_PE)) {
                outw(status | USBPORTSC_PE, port);      /* one more try at enabling port */
                wait_ms(50);
        }

}


/*
 * This gets called if the connect status on the root
 * hub (and the root hub only) changes.
 */
static void uhci_connect_change(struct uhci *uhci, unsigned int port, unsigned int nr)
{
        struct usb_device *usb_dev;
        struct uhci_device *dev;
        unsigned short status;

        printk("uhci_connect_change: called for %d\n", nr);

        /*
         * Even if the status says we're connected,
         * the fact that the status bits changed may
         * that we got disconnected and then reconnected.
         *
         * So start off by getting rid of any old devices..
         */
        usb_disconnect(&uhci->root_hub->usb->children[nr]);

        status = inw(port);

        /* If we have nothing connected, then clear change status and disable the port */
        status = (status & ~USBPORTSC_PE) | USBPORTSC_PEC;
        if (!(status & USBPORTSC_CCS)) {
                outw(status, port);
                return;
        }

        /*
         * Ok, we got a new connection. Allocate a device to it,
         * and find out what it wants to do..
         */
        usb_dev = uhci_usb_allocate(uhci->root_hub->usb);
        dev = usb_dev->hcpriv;

        dev->uhci = uhci;

        usb_connect(usb_dev);

        uhci->root_hub->usb->children[nr] = usb_dev;

        wait_ms(200); /* wait for powerup */
        uhci_reset_port(port);

        /* Get speed information */
        usb_dev->slow = (inw(port) & USBPORTSC_LSDA) ? 1 : 0;

        /*
         * Ok, all the stuff specific to the root hub has been done.
         * The rest is generic for any new USB attach, regardless of
         * hub type.
         */
        usb_new_device(usb_dev);
}

/*
 * This gets called when the root hub configuration
 * has changed. Just go through each port, seeing if
 * there is something interesting happening.
 */
static void uhci_check_configuration(struct uhci *uhci)
{
        unsigned int io_addr = uhci->io_addr + USBPORTSC1;
        int maxchild = uhci->root_hub->usb->maxchild;
        int nr = 0;

        do {
                unsigned short status = inw(io_addr);

                if (status & USBPORTSC_CSC)
                        uhci_connect_change(uhci, io_addr, nr);

                nr++; io_addr += 2;
        } while (nr < maxchild);
}

static void uhci_interrupt_notify(struct uhci *uhci)
{
        struct list_head *head = &uhci->interrupt_list;
        struct list_head *tmp;

        spin_lock(&irqlist_lock);
        tmp = head->next;
        while (tmp != head) {
                struct uhci_td *td = list_entry(tmp, struct uhci_td, irq_list);
                struct list_head *next;

                next = tmp->next;

                if (!(td->status & (1 << 23))) {        /* No longer active? */
                        /* remove from IRQ list */
                        __list_del(tmp->prev, next);
                        INIT_LIST_HEAD(tmp);
                        if (td->completed(td->status, bus_to_virt(td->buffer), td->dev_id)) {
                                struct uhci_qh *interrupt_qh = td->qh;

                                list_add(&td->irq_list, &uhci->interrupt_list);
                                td->info ^= 1 << 19; /* toggle between data0 and data1 */
                                td->status = (td->status & 0x2f000000) | (1 << 23) | (1 << 24); /* active */

                                /* Remove then readd? Is that necessary */
                                uhci_remove_td(td);
                                uhci_insert_td_in_qh(interrupt_qh, td);
                        }
                        /* If completed wants to not reactivate, then it's */
                        /* responsible for free'ing the TD's and QH's */
                        /* or another function (such as run_control) */
                }
                tmp = next;
        }
        spin_unlock(&irqlist_lock);
}

/*
 * Check port status - Connect Status Change - for
 * each of the attached ports (defaults to two ports,
 * but at least in theory there can be more of them).
 *
 * Wake up the configurator if something happened, we
 * can't really do much at interrupt time.
 */
static void uhci_root_hub_events(struct uhci *uhci, unsigned int io_addr)
{
        if (waitqueue_active(&uhci_configure)) {
                int ports = uhci->root_hub->usb->maxchild;
                io_addr += USBPORTSC1;
                do {
                        if (inw(io_addr) & USBPORTSC_CSC) {
                                wake_up(&uhci_configure);
                                return;
                        }
                        io_addr += 2;
                } while (--ports > 0);
        }
}

static void uhci_interrupt(int irq, void *__uhci, struct pt_regs *regs)
{
        struct uhci *uhci = __uhci;
        unsigned int io_addr = uhci->io_addr;
        unsigned short status;

        /*
         * Read the interrupt status, and write it back to clear the interrupt cause
         */
        status = inw(io_addr + USBSTS);
        outw(status, io_addr + USBSTS);

        /* Walk the list of pending TD's to see which ones completed.. */
        uhci_interrupt_notify(uhci);

        /* Check if there are any events on the root hub.. */
        uhci_root_hub_events(uhci, io_addr);
}

/*
 * We init one packet, and mark it just IOC and _not_
 * active. Which will result in no actual USB traffic,
 * but _will_ result in an interrupt every second.
 *
 * Which is exactly what we want.
 */
static void uhci_init_ticktd(struct uhci *uhci)
{
        struct uhci_device *dev = uhci->root_hub;
        struct uhci_td *td = uhci_td_allocate(dev);

        td->link = 1;
        td->status = (1 << 24);                                 /* interrupt on completion */
        td->info = (15 << 21) | 0x7f69;                         /* (ignored) input packet, 16 bytes, device 127 */
        td->buffer = 0;
        td->qh = NULL;

        uhci->fl->frame[0] = virt_to_bus(td);
}

static void reset_hc(struct uhci *uhci)
{
        unsigned int io_addr = uhci->io_addr;

        /* Global reset for 50ms */
        outw(USBCMD_GRESET, io_addr+USBCMD);
        wait_ms(50);
        outw(0, io_addr+USBCMD);
        wait_ms(10);
}

static void start_hc(struct uhci *uhci)
{
        unsigned int io_addr = uhci->io_addr;
        int timeout = 1000;

        uhci_init_ticktd(uhci);

        /*
         * Reset the HC - this will force us to get a
         * new notification of any already connected
         * ports due to the virtual disconnect that it
         * implies.
         */
        outw(USBCMD_HCRESET, io_addr + USBCMD);
        while (inw(io_addr + USBCMD) & USBCMD_HCRESET) {
                if (!--timeout) {
                        printk("USBCMD_HCRESET timed out!\n");
                        break;
                }
        }

        outw(USBINTR_TIMEOUT | USBINTR_RESUME | USBINTR_IOC | USBINTR_SP, io_addr + USBINTR);
        outw(0, io_addr + USBFRNUM);
        outl(virt_to_bus(uhci->fl), io_addr + USBFLBASEADD);

        /* Run and mark it configured with a 64-byte max packet */
        outw(USBCMD_RS | USBCMD_CF, io_addr + USBCMD);
}

/*
 * Allocate a frame list, and four regular queues.
 *
 * The hardware doesn't really know any difference
 * in the queues, but the order does matter for the
 * protocols higher up. The order is:
 *
 *  - any isochronous events handled before any
 *    of the queues. We don't do that here, because
 *    we'll create the actual TD entries on demand.
 *  - The first queue is the "interrupt queue".
 *  - The second queue is the "control queue".
 *  - The third queue is "bulk data".
 *
 * We could certainly have multiple queues of the same
 * type, and maybe we should. We could have per-device
 * queues, for example. We begin small.
 */
static struct uhci *alloc_uhci(unsigned int io_addr)
{
        int i;
        struct uhci *uhci;
        struct usb_bus *bus;
        struct uhci_device *dev;
        struct usb_device *usb;

        uhci = kmalloc(sizeof(*uhci), GFP_KERNEL);
        if (!uhci)
                return NULL;

        memset(uhci, 0, sizeof(*uhci));

        uhci->irq = -1;
        uhci->io_addr = io_addr;
        INIT_LIST_HEAD(&uhci->interrupt_list);

        /* We need exactly one page (per UHCI specs), how convenient */
        uhci->fl = (void *)__get_free_page(GFP_KERNEL);

        bus = kmalloc(sizeof(*bus), GFP_KERNEL);
        if (!bus)
                return NULL;

        memset(bus, 0, sizeof(*bus));

        uhci->bus = bus;
        bus->hcpriv = uhci;
        bus->op = &uhci_device_operations;

        /*
         * We allocate a 8kB area for the UHCI hub. The area
         * is described by the uhci_device structure, and basically
         * contains everything needed for normal operation.
         *
         * The first page is the actual device descriptor for the
         * hub.
         *
         * The second page is used for the frame list.
         */
        usb = uhci_usb_allocate(NULL);
        if (!usb)
                return NULL;

        dev = uhci->root_hub = usb_to_uhci(usb);

        usb->bus = bus;

        /* Initialize the root hub */
        /* UHCI specs says devices must have 2 ports, but goes on to say */
        /* they may have more but give no way to determine how many they */
        /* have, so default to 2 */
        usb->maxchild = 2;
        usb_init_root_hub(usb);

        /*
         * Initialize the queues. They all start out empty,
         * linked to each other in the proper order.
         */
        for (i = 1 ; i < 9; i++) {
                dev->qh[i].link = 2 | virt_to_bus(&dev->skel_control_qh);
                dev->qh[i].element = 1;
        }
        
        dev->skel_control_qh.link = 2 | virt_to_bus(&dev->skel_bulk0_qh);
        dev->skel_control_qh.element = 1;

        dev->skel_bulk0_qh.link = 2 | virt_to_bus(&dev->skel_bulk1_qh);
        dev->skel_bulk0_qh.element = 1;

        dev->skel_bulk1_qh.link = 2 | virt_to_bus(&dev->skel_bulk2_qh);
        dev->skel_bulk1_qh.element = 1;

        dev->skel_bulk2_qh.link = 2 | virt_to_bus(&dev->skel_bulk3_qh);
        dev->skel_bulk2_qh.element = 1;

        dev->skel_bulk3_qh.link = 1;
        dev->skel_bulk3_qh.element = 1;

        /*
         * Fill the frame list: make all entries point to
         * the proper interrupt queue.
         *
         * This is probably silly, but it's a simple way to
         * scatter the interrupt queues in a way that gives
         * us a reasonable dynamic range for irq latencies.
         */
        for (i = 0; i < 1024; i++) {
                struct uhci_qh * irq = &dev->skel_int2_qh;
                if (i & 1) {
                        irq++;
                        if (i & 2) {
                                irq++;
                                if (i & 4) { 
                                        irq++;
                                        if (i & 8) { 
                                                irq++;
                                                if (i & 16) {
                                                        irq++;
                                                        if (i & 32) {
                                                                irq++;
                                                                if (i & 64) {
                                                                        irq++;
                                                                }
                                                        }
                                                }
                                        }
                                }
                        }
                }
                uhci->fl->frame[i] =  2 | virt_to_bus(irq);
        }

        return uhci;
}


/*
 * De-allocate all resources..
 */
static void release_uhci(struct uhci *uhci)
{
        if (uhci->irq >= 0) {
                free_irq(uhci->irq, uhci);
                uhci->irq = -1;
        }

#if 0
        if (uhci->root_hub) {
                uhci_usb_deallocate(uhci_to_usb(uhci->root_hub));
                uhci->root_hub = NULL;
        }
#endif

        if (uhci->fl) {
                free_page((unsigned long)uhci->fl);
                uhci->fl = NULL;
        }

        kfree(uhci->bus);
        kfree(uhci);
}

void cleanup_drivers(void);

static int uhci_control_thread(void * __uhci)
{
        struct uhci *uhci = (struct uhci *)__uhci;

        lock_kernel();
        request_region(uhci->io_addr, 32, "usb-uhci");

        /*
         * This thread doesn't need any user-level access,
         * so get rid of all our resources..
         */
        printk("uhci_control_thread at %p\n", &uhci_control_thread);
        exit_mm(current);
        exit_files(current);
        exit_fs(current);

        strcpy(current->comm, "uhci-control");

        /*
         * Ok, all systems are go..
         */
        start_hc(uhci);
        for(;;) {
                siginfo_t info;
                int unsigned long signr;

                interruptible_sleep_on(&uhci_configure);
#ifdef CONFIG_APM
                if (apm_resume) {
                        apm_resume = 0;
                        start_hc(uhci);
                        continue;
                }
#endif
                uhci_check_configuration(uhci);

                if(signal_pending(current)) {
                        /* sending SIGUSR1 makes us print out some info */
                        spin_lock_irq(&current->sigmask_lock);
                        signr = dequeue_signal(&current->blocked, &info);
                        spin_unlock_irq(&current->sigmask_lock);

                        if(signr == SIGUSR1) {
                                printk("UHCI queue dump:\n");
                                show_queues(uhci);
                        } else {
                                break;
                        }
                }
        }

#if 0
        if(uhci->root_hub)
                for(i = 0; i < uhci->root_hub->usb->maxchild; i++)
                        usb_disconnect(uhci->root_hub->usb->children + i);
#endif

        cleanup_drivers();

        reset_hc(uhci);
        release_region(uhci->io_addr, 32);

        release_uhci(uhci);
        MOD_DEC_USE_COUNT;

        printk("uhci_control_thread exiting\n");

        return 0;
}       

/*
 * If we've successfully found a UHCI, now is the time to increment the
 * module usage count, start the control thread, and return success..
 */
static int found_uhci(int irq, unsigned int io_addr)
{
        int retval;
        struct uhci *uhci;

        uhci = alloc_uhci(io_addr);
        if (!uhci)
                return -ENOMEM;

        reset_hc(uhci);

        retval = -EBUSY;
        if (request_irq(irq, uhci_interrupt, SA_SHIRQ, "usb", uhci) == 0) {
                int pid;

                MOD_INC_USE_COUNT;
                uhci->irq = irq;
                pid = kernel_thread(uhci_control_thread, uhci, CLONE_FS | CLONE_FILES | CLONE_SIGHAND);
                if (pid >= 0)
                        return 0;

                MOD_DEC_USE_COUNT;
                retval = pid;
        }
        release_uhci(uhci);
        return retval;
}

static int start_uhci(struct pci_dev *dev)
{
        int i;

        /* Search for the IO base address.. */
        for (i = 0; i < 6; i++) {
                unsigned int io_addr = dev->base_address[i];

                /* IO address? */
                if (!(io_addr & 1))
                        continue;

                io_addr &= PCI_BASE_ADDRESS_IO_MASK;

                /* Is it already in use? */
                if (check_region(io_addr, 32))
                        break;

                return found_uhci(dev->irq, io_addr);
        }
        return -1;
}

#ifdef CONFIG_APM
static int handle_apm_event(apm_event_t event)
{
        static int down = 0;

        switch (event) {
        case APM_SYS_SUSPEND:
        case APM_USER_SUSPEND:
                if (down) {
                        printk(KERN_DEBUG "uhci: received extra suspend event\n");
                        break;
                }
                down = 1;
                break;
        case APM_NORMAL_RESUME:
        case APM_CRITICAL_RESUME:
                if (!down) {
                        printk(KERN_DEBUG "uhci: received bogus resume event\n");
                        break;
                }
                down = 0;
                if (waitqueue_active(&uhci_configure)) {
                        apm_resume = 1;
                        wake_up(&uhci_configure);
                }
                break;
        }
        return 0;
}
#endif

#ifdef MODULE

void cleanup_module(void)
{
#ifdef CONFIG_APM
        apm_unregister_callback(&handle_apm_event);
#endif
}

#define uhci_init init_module

#endif

int uhci_init(void)
{
        int retval;
        struct pci_dev *dev = NULL;
        u8 type;

        retval = -ENODEV;
        for (;;) {
                dev = pci_find_class(PCI_CLASS_SERIAL_USB<<8, dev);
                if (!dev)
                        break;
                /* Is it UHCI */
                pci_read_config_byte(dev, PCI_CLASS_PROG, &type);
                if(type != 0)
                        continue;
                /* Ok set it up */
                retval = start_uhci(dev);
                if (retval < 0)
                        continue;

#ifdef CONFIG_USB_MOUSE
                usb_mouse_init();
#endif
#ifdef CONFIG_USB_KBD           
                usb_kbd_init();
#endif          
                hub_init();
#ifdef CONFIG_USB_AUDIO         
                usb_audio_init();
#endif          
#ifdef CONFIG_APM
                apm_register_callback(&handle_apm_event);
#endif

                return 0;
        }
        return retval;
}

void cleanup_drivers(void)
{
        hub_cleanup();
#ifdef CONFIG_USB_MOUSE
        usb_mouse_cleanup();
#endif
}