Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 919 insertions, 0 deletions

diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c
new file mode 100644
index 000000000000..324a1a9bbdb2
--- /dev/null
+++ b/drivers/usb/host/uhci-hcd.c
@@ -0,0 +1,919 @@
+/*
+ * Universal Host Controller Interface driver for USB.
+ *
+ * Maintainer: Alan Stern <stern@rowland.harvard.edu>
+ *
+ * (C) Copyright 1999 Linus Torvalds
+ * (C) Copyright 1999-2002 Johannes Erdfelt, johannes@erdfelt.com
+ * (C) Copyright 1999 Randy Dunlap
+ * (C) Copyright 1999 Georg Acher, acher@in.tum.de
+ * (C) Copyright 1999 Deti Fliegl, deti@fliegl.de
+ * (C) Copyright 1999 Thomas Sailer, sailer@ife.ee.ethz.ch
+ * (C) Copyright 1999 Roman Weissgaerber, weissg@vienna.at
+ * (C) Copyright 2000 Yggdrasil Computing, Inc. (port of new PCI interface
+ *               support from usb-ohci.c by Adam Richter, adam@yggdrasil.com).
+ * (C) Copyright 1999 Gregory P. Smith (from usb-ohci.c)
+ * (C) Copyright 2004 Alan Stern, stern@rowland.harvard.edu
+ *
+ * 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.
+ *
+ * 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
+ */
+
+#include <linux/config.h>
+#ifdef CONFIG_USB_DEBUG
+#define DEBUG
+#else
+#undef DEBUG
+#endif
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/ioport.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/smp_lock.h>
+#include <linux/errno.h>
+#include <linux/unistd.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/debugfs.h>
+#include <linux/pm.h>
+#include <linux/dmapool.h>
+#include <linux/dma-mapping.h>
+#include <linux/usb.h>
+#include <linux/bitops.h>
+
+#include <asm/uaccess.h>
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/system.h>
+
+#include "../core/hcd.h"
+#include "uhci-hcd.h"
+
+/*
+ * Version Information
+ */
+#define DRIVER_VERSION "v2.2"
+#define DRIVER_AUTHOR "Linus 'Frodo Rabbit' Torvalds, Johannes Erdfelt, \
+Randy Dunlap, Georg Acher, Deti Fliegl, Thomas Sailer, Roman Weissgaerber, \
+Alan Stern"
+#define DRIVER_DESC "USB Universal Host Controller Interface driver"
+
+/*
+ * debug = 0, no debugging messages
+ * debug = 1, dump failed URB's except for stalls
+ * debug = 2, dump all failed URB's (including stalls)
+ *            show all queues in /debug/uhci/[pci_addr]
+ * debug = 3, show all TD's in URB's when dumping
+ */
+#ifdef DEBUG
+static int debug = 1;
+#else
+static int debug = 0;
+#endif
+module_param(debug, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Debug level");
+static char *errbuf;
+#define ERRBUF_LEN    (32 * 1024)
+
+static kmem_cache_t *uhci_up_cachep;    /* urb_priv */
+
+static void uhci_get_current_frame_number(struct uhci_hcd *uhci);
+static void hc_state_transitions(struct uhci_hcd *uhci);
+
+/* If a transfer is still active after this much time, turn off FSBR */
+#define IDLE_TIMEOUT    msecs_to_jiffies(50)
+#define FSBR_DELAY      msecs_to_jiffies(50)
+
+/* When we timeout an idle transfer for FSBR, we'll switch it over to */
+/* depth first traversal. We'll do it in groups of this number of TD's */
+/* to make sure it doesn't hog all of the bandwidth */
+#define DEPTH_INTERVAL 5
+
+#include "uhci-hub.c"
+#include "uhci-debug.c"
+#include "uhci-q.c"
+
+static int init_stall_timer(struct usb_hcd *hcd);
+
+static void stall_callback(unsigned long ptr)
+{
+        struct usb_hcd *hcd = (struct usb_hcd *)ptr;
+        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+        struct urb_priv *up;
+        unsigned long flags;
+
+        spin_lock_irqsave(&uhci->lock, flags);
+        uhci_scan_schedule(uhci, NULL);
+
+        list_for_each_entry(up, &uhci->urb_list, urb_list) {
+                struct urb *u = up->urb;
+
+                spin_lock(&u->lock);
+
+                /* Check if the FSBR timed out */
+                if (up->fsbr && !up->fsbr_timeout && time_after_eq(jiffies, up->fsbrtime + IDLE_TIMEOUT))
+                        uhci_fsbr_timeout(uhci, u);
+
+                spin_unlock(&u->lock);
+        }
+
+        /* Really disable FSBR */
+        if (!uhci->fsbr && uhci->fsbrtimeout && time_after_eq(jiffies, uhci->fsbrtimeout)) {
+                uhci->fsbrtimeout = 0;
+                uhci->skel_term_qh->link = UHCI_PTR_TERM;
+        }
+
+        /* Poll for and perform state transitions */
+        hc_state_transitions(uhci);
+        if (unlikely(uhci->suspended_ports && uhci->state != UHCI_SUSPENDED))
+                uhci_check_ports(uhci);
+
+        init_stall_timer(hcd);
+        spin_unlock_irqrestore(&uhci->lock, flags);
+}
+
+static int init_stall_timer(struct usb_hcd *hcd)
+{
+        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+
+        init_timer(&uhci->stall_timer);
+        uhci->stall_timer.function = stall_callback;
+        uhci->stall_timer.data = (unsigned long)hcd;
+        uhci->stall_timer.expires = jiffies + msecs_to_jiffies(100);
+        add_timer(&uhci->stall_timer);
+
+        return 0;
+}
+
+static irqreturn_t uhci_irq(struct usb_hcd *hcd, struct pt_regs *regs)
+{
+        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+        unsigned long io_addr = uhci->io_addr;
+        unsigned short status;
+
+        /*
+         * Read the interrupt status, and write it back to clear the
+         * interrupt cause.  Contrary to the UHCI specification, the
+         * "HC Halted" status bit is persistent: it is RO, not R/WC.
+         */
+        status = inw(io_addr + USBSTS);
+        if (!(status & ~USBSTS_HCH))    /* shared interrupt, not mine */
+                return IRQ_NONE;
+        outw(status, io_addr + USBSTS);         /* Clear it */
+
+        if (status & ~(USBSTS_USBINT | USBSTS_ERROR | USBSTS_RD)) {
+                if (status & USBSTS_HSE)
+                        dev_err(uhci_dev(uhci), "host system error, "
+                                        "PCI problems?\n");
+                if (status & USBSTS_HCPE)
+                        dev_err(uhci_dev(uhci), "host controller process "
+                                        "error, something bad happened!\n");
+                if ((status & USBSTS_HCH) && uhci->state > 0) {
+                        dev_err(uhci_dev(uhci), "host controller halted, "
+                                        "very bad!\n");
+                        /* FIXME: Reset the controller, fix the offending TD */
+                }
+        }
+
+        if (status & USBSTS_RD)
+                uhci->resume_detect = 1;
+
+        spin_lock(&uhci->lock);
+        uhci_scan_schedule(uhci, regs);
+        spin_unlock(&uhci->lock);
+
+        return IRQ_HANDLED;
+}
+
+static void reset_hc(struct uhci_hcd *uhci)
+{
+        unsigned long io_addr = uhci->io_addr;
+
+        /* Turn off PIRQ, SMI, and all interrupts.  This also turns off
+         * the BIOS's USB Legacy Support.
+         */
+        pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP, 0);
+        outw(0, uhci->io_addr + USBINTR);
+
+        /* Global reset for 50ms */
+        uhci->state = UHCI_RESET;
+        outw(USBCMD_GRESET, io_addr + USBCMD);
+        msleep(50);
+        outw(0, io_addr + USBCMD);
+
+        /* Another 10ms delay */
+        msleep(10);
+        uhci->resume_detect = 0;
+        uhci->is_stopped = UHCI_IS_STOPPED;
+}
+
+static void suspend_hc(struct uhci_hcd *uhci)
+{
+        unsigned long io_addr = uhci->io_addr;
+
+        dev_dbg(uhci_dev(uhci), "%s\n", __FUNCTION__);
+        uhci->state = UHCI_SUSPENDED;
+        uhci->resume_detect = 0;
+        outw(USBCMD_EGSM, io_addr + USBCMD);
+
+        /* FIXME: Wait for the controller to actually stop */
+        uhci_get_current_frame_number(uhci);
+        uhci->is_stopped = UHCI_IS_STOPPED;
+
+        uhci_scan_schedule(uhci, NULL);
+}
+
+static void wakeup_hc(struct uhci_hcd *uhci)
+{
+        unsigned long io_addr = uhci->io_addr;
+
+        switch (uhci->state) {
+                case UHCI_SUSPENDED:            /* Start the resume */
+                        dev_dbg(uhci_dev(uhci), "%s\n", __FUNCTION__);
+
+                        /* Global resume for >= 20ms */
+                        outw(USBCMD_FGR | USBCMD_EGSM, io_addr + USBCMD);
+                        uhci->state = UHCI_RESUMING_1;
+                        uhci->state_end = jiffies + msecs_to_jiffies(20);
+                        uhci->is_stopped = 0;
+                        break;
+
+                case UHCI_RESUMING_1:           /* End global resume */
+                        uhci->state = UHCI_RESUMING_2;
+                        outw(0, io_addr + USBCMD);
+                        /* Falls through */
+
+                case UHCI_RESUMING_2:           /* Wait for EOP to be sent */
+                        if (inw(io_addr + USBCMD) & USBCMD_FGR)
+                                break;
+
+                        /* Run for at least 1 second, and
+                         * mark it configured with a 64-byte max packet */
+                        uhci->state = UHCI_RUNNING_GRACE;
+                        uhci->state_end = jiffies + HZ;
+                        outw(USBCMD_RS | USBCMD_CF | USBCMD_MAXP,
+                                        io_addr + USBCMD);
+                        break;
+
+                case UHCI_RUNNING_GRACE:        /* Now allowed to suspend */
+                        uhci->state = UHCI_RUNNING;
+                        break;
+
+                default:
+                        break;
+        }
+}
+
+static int ports_active(struct uhci_hcd *uhci)
+{
+        unsigned long io_addr = uhci->io_addr;
+        int connection = 0;
+        int i;
+
+        for (i = 0; i < uhci->rh_numports; i++)
+                connection |= (inw(io_addr + USBPORTSC1 + i * 2) & USBPORTSC_CCS);
+
+        return connection;
+}
+
+static int suspend_allowed(struct uhci_hcd *uhci)
+{
+        unsigned long io_addr = uhci->io_addr;
+        int i;
+
+        if (to_pci_dev(uhci_dev(uhci))->vendor != PCI_VENDOR_ID_INTEL)
+                return 1;
+
+        /* Some of Intel's USB controllers have a bug that causes false
+         * resume indications if any port has an over current condition.
+         * To prevent problems, we will not allow a global suspend if
+         * any ports are OC.
+         *
+         * Some motherboards using Intel's chipsets (but not using all
+         * the USB ports) appear to hardwire the over current inputs active
+         * to disable the USB ports.
+         */
+
+        /* check for over current condition on any port */
+        for (i = 0; i < uhci->rh_numports; i++) {
+                if (inw(io_addr + USBPORTSC1 + i * 2) & USBPORTSC_OC)
+                        return 0;
+        }
+
+        return 1;
+}
+
+static void hc_state_transitions(struct uhci_hcd *uhci)
+{
+        switch (uhci->state) {
+                case UHCI_RUNNING:
+
+                        /* global suspend if nothing connected for 1 second */
+                        if (!ports_active(uhci) && suspend_allowed(uhci)) {
+                                uhci->state = UHCI_SUSPENDING_GRACE;
+                                uhci->state_end = jiffies + HZ;
+                        }
+                        break;
+
+                case UHCI_SUSPENDING_GRACE:
+                        if (ports_active(uhci))
+                                uhci->state = UHCI_RUNNING;
+                        else if (time_after_eq(jiffies, uhci->state_end))
+                                suspend_hc(uhci);
+                        break;
+
+                case UHCI_SUSPENDED:
+
+                        /* wakeup if requested by a device */
+                        if (uhci->resume_detect)
+                                wakeup_hc(uhci);
+                        break;
+
+                case UHCI_RESUMING_1:
+                case UHCI_RESUMING_2:
+                case UHCI_RUNNING_GRACE:
+                        if (time_after_eq(jiffies, uhci->state_end))
+                                wakeup_hc(uhci);
+                        break;
+
+                default:
+                        break;
+        }
+}
+
+/*
+ * Store the current frame number in uhci->frame_number if the controller
+ * is runnning
+ */
+static void uhci_get_current_frame_number(struct uhci_hcd *uhci)
+{
+        if (!uhci->is_stopped)
+                uhci->frame_number = inw(uhci->io_addr + USBFRNUM);
+}
+
+static int start_hc(struct uhci_hcd *uhci)
+{
+        unsigned long io_addr = uhci->io_addr;
+        int timeout = 10;
+
+        /*
+         * 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 < 0) {
+                        dev_err(uhci_dev(uhci), "USBCMD_HCRESET timed out!\n");
+                        return -ETIMEDOUT;
+                }
+                msleep(1);
+        }
+
+        /* Mark controller as running before we enable interrupts */
+        uhci_to_hcd(uhci)->state = HC_STATE_RUNNING;
+
+        /* Turn on PIRQ and all interrupts */
+        pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP,
+                        USBLEGSUP_DEFAULT);
+        outw(USBINTR_TIMEOUT | USBINTR_RESUME | USBINTR_IOC | USBINTR_SP,
+                io_addr + USBINTR);
+
+        /* Start at frame 0 */
+        outw(0, io_addr + USBFRNUM);
+        outl(uhci->fl->dma_handle, io_addr + USBFLBASEADD);
+
+        /* Run and mark it configured with a 64-byte max packet */
+        uhci->state = UHCI_RUNNING_GRACE;
+        uhci->state_end = jiffies + HZ;
+        outw(USBCMD_RS | USBCMD_CF | USBCMD_MAXP, io_addr + USBCMD);
+        uhci->is_stopped = 0;
+
+        return 0;
+}
+
+/*
+ * De-allocate all resources
+ */
+static void release_uhci(struct uhci_hcd *uhci)
+{
+        int i;
+
+        for (i = 0; i < UHCI_NUM_SKELQH; i++)
+                if (uhci->skelqh[i]) {
+                        uhci_free_qh(uhci, uhci->skelqh[i]);
+                        uhci->skelqh[i] = NULL;
+                }
+
+        if (uhci->term_td) {
+                uhci_free_td(uhci, uhci->term_td);
+                uhci->term_td = NULL;
+        }
+
+        if (uhci->qh_pool) {
+                dma_pool_destroy(uhci->qh_pool);
+                uhci->qh_pool = NULL;
+        }
+
+        if (uhci->td_pool) {
+                dma_pool_destroy(uhci->td_pool);
+                uhci->td_pool = NULL;
+        }
+
+        if (uhci->fl) {
+                dma_free_coherent(uhci_dev(uhci), sizeof(*uhci->fl),
+                                uhci->fl, uhci->fl->dma_handle);
+                uhci->fl = NULL;
+        }
+
+        if (uhci->dentry) {
+                debugfs_remove(uhci->dentry);
+                uhci->dentry = NULL;
+        }
+}
+
+static int uhci_reset(struct usb_hcd *hcd)
+{
+        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+
+        uhci->io_addr = (unsigned long) hcd->rsrc_start;
+
+        /* Kick BIOS off this hardware and reset, so we won't get
+         * interrupts from any previous setup.
+         */
+        reset_hc(uhci);
+        return 0;
+}
+
+/*
+ * Allocate a frame list, and then setup the skeleton
+ *
+ * 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, split into low- and full-speed
+ *  - The third queue is bulk queue.
+ *  - The fourth queue is the bandwidth reclamation queue, which loops back
+ *    to the full-speed control queue.
+ */
+static int uhci_start(struct usb_hcd *hcd)
+{
+        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+        int retval = -EBUSY;
+        int i, port;
+        unsigned io_size;
+        dma_addr_t dma_handle;
+        struct usb_device *udev;
+        struct dentry *dentry;
+
+        io_size = (unsigned) hcd->rsrc_len;
+
+        dentry = debugfs_create_file(hcd->self.bus_name, S_IFREG|S_IRUGO|S_IWUSR, uhci_debugfs_root, uhci, &uhci_debug_operations);
+        if (!dentry) {
+                dev_err(uhci_dev(uhci), "couldn't create uhci debugfs entry\n");
+                retval = -ENOMEM;
+                goto err_create_debug_entry;
+        }
+        uhci->dentry = dentry;
+
+        uhci->fsbr = 0;
+        uhci->fsbrtimeout = 0;
+
+        spin_lock_init(&uhci->lock);
+        INIT_LIST_HEAD(&uhci->qh_remove_list);
+
+        INIT_LIST_HEAD(&uhci->td_remove_list);
+
+        INIT_LIST_HEAD(&uhci->urb_remove_list);
+
+        INIT_LIST_HEAD(&uhci->urb_list);
+
+        INIT_LIST_HEAD(&uhci->complete_list);
+
+        init_waitqueue_head(&uhci->waitqh);
+
+        uhci->fl = dma_alloc_coherent(uhci_dev(uhci), sizeof(*uhci->fl),
+                        &dma_handle, 0);
+        if (!uhci->fl) {
+                dev_err(uhci_dev(uhci), "unable to allocate "
+                                "consistent memory for frame list\n");
+                goto err_alloc_fl;
+        }
+
+        memset((void *)uhci->fl, 0, sizeof(*uhci->fl));
+
+        uhci->fl->dma_handle = dma_handle;
+
+        uhci->td_pool = dma_pool_create("uhci_td", uhci_dev(uhci),
+                        sizeof(struct uhci_td), 16, 0);
+        if (!uhci->td_pool) {
+                dev_err(uhci_dev(uhci), "unable to create td dma_pool\n");
+                goto err_create_td_pool;
+        }
+
+        uhci->qh_pool = dma_pool_create("uhci_qh", uhci_dev(uhci),
+                        sizeof(struct uhci_qh), 16, 0);
+        if (!uhci->qh_pool) {
+                dev_err(uhci_dev(uhci), "unable to create qh dma_pool\n");
+                goto err_create_qh_pool;
+        }
+
+        /* 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. However, according to the UHCI spec, Bit 7 is always set */
+        /*  to 1. So we try to use this to our advantage */
+        for (port = 0; port < (io_size - 0x10) / 2; port++) {
+                unsigned int portstatus;
+
+                portstatus = inw(uhci->io_addr + 0x10 + (port * 2));
+                if (!(portstatus & 0x0080))
+                        break;
+        }
+        if (debug)
+                dev_info(uhci_dev(uhci), "detected %d ports\n", port);
+
+        /* This is experimental so anything less than 2 or greater than 8 is */
+        /*  something weird and we'll ignore it */
+        if (port < 2 || port > UHCI_RH_MAXCHILD) {
+                dev_info(uhci_dev(uhci), "port count misdetected? "
+                                "forcing to 2 ports\n");
+                port = 2;
+        }
+
+        uhci->rh_numports = port;
+
+        udev = usb_alloc_dev(NULL, &hcd->self, 0);
+        if (!udev) {
+                dev_err(uhci_dev(uhci), "unable to allocate root hub\n");
+                goto err_alloc_root_hub;
+        }
+
+        uhci->term_td = uhci_alloc_td(uhci, udev);
+        if (!uhci->term_td) {
+                dev_err(uhci_dev(uhci), "unable to allocate terminating TD\n");
+                goto err_alloc_term_td;
+        }
+
+        for (i = 0; i < UHCI_NUM_SKELQH; i++) {
+                uhci->skelqh[i] = uhci_alloc_qh(uhci, udev);
+                if (!uhci->skelqh[i]) {
+                        dev_err(uhci_dev(uhci), "unable to allocate QH\n");
+                        goto err_alloc_skelqh;
+                }
+        }
+
+        /*
+         * 8 Interrupt queues; link all higher int queues to int1,
+         * then link int1 to control and control to bulk
+         */
+        uhci->skel_int128_qh->link =
+                        uhci->skel_int64_qh->link =
+                        uhci->skel_int32_qh->link =
+                        uhci->skel_int16_qh->link =
+                        uhci->skel_int8_qh->link =
+                        uhci->skel_int4_qh->link =
+                        uhci->skel_int2_qh->link =
+                        cpu_to_le32(uhci->skel_int1_qh->dma_handle) | UHCI_PTR_QH;
+        uhci->skel_int1_qh->link = cpu_to_le32(uhci->skel_ls_control_qh->dma_handle) | UHCI_PTR_QH;
+
+        uhci->skel_ls_control_qh->link = cpu_to_le32(uhci->skel_fs_control_qh->dma_handle) | UHCI_PTR_QH;
+        uhci->skel_fs_control_qh->link = cpu_to_le32(uhci->skel_bulk_qh->dma_handle) | UHCI_PTR_QH;
+        uhci->skel_bulk_qh->link = cpu_to_le32(uhci->skel_term_qh->dma_handle) | UHCI_PTR_QH;
+
+        /* This dummy TD is to work around a bug in Intel PIIX controllers */
+        uhci_fill_td(uhci->term_td, 0, (UHCI_NULL_DATA_SIZE << 21) |
+                (0x7f << TD_TOKEN_DEVADDR_SHIFT) | USB_PID_IN, 0);
+        uhci->term_td->link = cpu_to_le32(uhci->term_td->dma_handle);
+
+        uhci->skel_term_qh->link = UHCI_PTR_TERM;
+        uhci->skel_term_qh->element = cpu_to_le32(uhci->term_td->dma_handle);
+
+        /*
+         * Fill the frame list: make all entries point to the proper
+         * interrupt queue.
+         *
+         * The interrupt queues will be interleaved as evenly as possible.
+         * There's not much to be done about period-1 interrupts; they have
+         * to occur in every frame.  But we can schedule period-2 interrupts
+         * in odd-numbered frames, period-4 interrupts in frames congruent
+         * to 2 (mod 4), and so on.  This way each frame only has two
+         * interrupt QHs, which will help spread out bandwidth utilization.
+         */
+        for (i = 0; i < UHCI_NUMFRAMES; i++) {
+                int irq;
+
+                /*
+                 * ffs (Find First bit Set) does exactly what we need:
+                 * 1,3,5,...  => ffs = 0 => use skel_int2_qh = skelqh[6],
+                 * 2,6,10,... => ffs = 1 => use skel_int4_qh = skelqh[5], etc.
+                 * ffs > 6 => not on any high-period queue, so use
+                 *      skel_int1_qh = skelqh[7].
+                 * Add UHCI_NUMFRAMES to insure at least one bit is set.
+                 */
+                irq = 6 - (int) __ffs(i + UHCI_NUMFRAMES);
+                if (irq < 0)
+                        irq = 7;
+
+                /* Only place we don't use the frame list routines */
+                uhci->fl->frame[i] = UHCI_PTR_QH |
+                                cpu_to_le32(uhci->skelqh[irq]->dma_handle);
+        }
+
+        /*
+         * Some architectures require a full mb() to enforce completion of
+         * the memory writes above before the I/O transfers in start_hc().
+         */
+        mb();
+        if ((retval = start_hc(uhci)) != 0)
+                goto err_alloc_skelqh;
+
+        init_stall_timer(hcd);
+
+        udev->speed = USB_SPEED_FULL;
+
+        if (usb_hcd_register_root_hub(udev, hcd) != 0) {
+                dev_err(uhci_dev(uhci), "unable to start root hub\n");
+                retval = -ENOMEM;
+                goto err_start_root_hub;
+        }
+
+        return 0;
+
+/*
+ * error exits:
+ */
+err_start_root_hub:
+        reset_hc(uhci);
+
+        del_timer_sync(&uhci->stall_timer);
+
+err_alloc_skelqh:
+        for (i = 0; i < UHCI_NUM_SKELQH; i++)
+                if (uhci->skelqh[i]) {
+                        uhci_free_qh(uhci, uhci->skelqh[i]);
+                        uhci->skelqh[i] = NULL;
+                }
+
+        uhci_free_td(uhci, uhci->term_td);
+        uhci->term_td = NULL;
+
+err_alloc_term_td:
+        usb_put_dev(udev);
+
+err_alloc_root_hub:
+        dma_pool_destroy(uhci->qh_pool);
+        uhci->qh_pool = NULL;
+
+err_create_qh_pool:
+        dma_pool_destroy(uhci->td_pool);
+        uhci->td_pool = NULL;
+
+err_create_td_pool:
+        dma_free_coherent(uhci_dev(uhci), sizeof(*uhci->fl),
+                        uhci->fl, uhci->fl->dma_handle);
+        uhci->fl = NULL;
+
+err_alloc_fl:
+        debugfs_remove(uhci->dentry);
+        uhci->dentry = NULL;
+
+err_create_debug_entry:
+        return retval;
+}
+
+static void uhci_stop(struct usb_hcd *hcd)
+{
+        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+
+        del_timer_sync(&uhci->stall_timer);
+        reset_hc(uhci);
+
+        spin_lock_irq(&uhci->lock);
+        uhci_scan_schedule(uhci, NULL);
+        spin_unlock_irq(&uhci->lock);
+        
+        release_uhci(uhci);
+}
+
+#ifdef CONFIG_PM
+static int uhci_suspend(struct usb_hcd *hcd, u32 state)
+{
+        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+
+        spin_lock_irq(&uhci->lock);
+
+        /* Don't try to suspend broken motherboards, reset instead */
+        if (suspend_allowed(uhci))
+                suspend_hc(uhci);
+        else {
+                spin_unlock_irq(&uhci->lock);
+                reset_hc(uhci);
+                spin_lock_irq(&uhci->lock);
+                uhci_scan_schedule(uhci, NULL);
+        }
+
+        spin_unlock_irq(&uhci->lock);
+        return 0;
+}
+
+static int uhci_resume(struct usb_hcd *hcd)
+{
+        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+        int rc;
+
+        pci_set_master(to_pci_dev(uhci_dev(uhci)));
+
+        spin_lock_irq(&uhci->lock);
+
+        if (uhci->state == UHCI_SUSPENDED) {
+
+                /*
+                 * Some systems don't maintain the UHCI register values
+                 * during a PM suspend/resume cycle, so reinitialize
+                 * the Frame Number, Framelist Base Address, Interrupt
+                 * Enable, and Legacy Support registers.
+                 */
+                pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP,
+                                0);
+                outw(uhci->frame_number, uhci->io_addr + USBFRNUM);
+                outl(uhci->fl->dma_handle, uhci->io_addr + USBFLBASEADD);
+                outw(USBINTR_TIMEOUT | USBINTR_RESUME | USBINTR_IOC |
+                                USBINTR_SP, uhci->io_addr + USBINTR);
+                uhci->resume_detect = 1;
+                pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP,
+                                USBLEGSUP_DEFAULT);
+        } else {
+                spin_unlock_irq(&uhci->lock);
+                reset_hc(uhci);
+                if ((rc = start_hc(uhci)) != 0)
+                        return rc;
+                spin_lock_irq(&uhci->lock);
+        }
+        hcd->state = HC_STATE_RUNNING;
+
+        spin_unlock_irq(&uhci->lock);
+        return 0;
+}
+#endif
+
+/* Wait until all the URBs for a particular device/endpoint are gone */
+static void uhci_hcd_endpoint_disable(struct usb_hcd *hcd,
+                struct usb_host_endpoint *ep)
+{
+        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+
+        wait_event_interruptible(uhci->waitqh, list_empty(&ep->urb_list));
+}
+
+static int uhci_hcd_get_frame_number(struct usb_hcd *hcd)
+{
+        struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+        int frame_number;
+        unsigned long flags;
+
+        /* Minimize latency by avoiding the spinlock */
+        local_irq_save(flags);
+        rmb();
+        frame_number = (uhci->is_stopped ? uhci->frame_number :
+                        inw(uhci->io_addr + USBFRNUM));
+        local_irq_restore(flags);
+        return frame_number;
+}
+
+static const char hcd_name[] = "uhci_hcd";
+
+static const struct hc_driver uhci_driver = {
+        .description =          hcd_name,
+        .product_desc =         "UHCI Host Controller",
+        .hcd_priv_size =        sizeof(struct uhci_hcd),
+
+        /* Generic hardware linkage */
+        .irq =                  uhci_irq,
+        .flags =                HCD_USB11,
+
+        /* Basic lifecycle operations */
+        .reset =                uhci_reset,
+        .start =                uhci_start,
+#ifdef CONFIG_PM
+        .suspend =              uhci_suspend,
+        .resume =               uhci_resume,
+#endif
+        .stop =                 uhci_stop,
+
+        .urb_enqueue =          uhci_urb_enqueue,
+        .urb_dequeue =          uhci_urb_dequeue,
+
+        .endpoint_disable =     uhci_hcd_endpoint_disable,
+        .get_frame_number =     uhci_hcd_get_frame_number,
+
+        .hub_status_data =      uhci_hub_status_data,
+        .hub_control =          uhci_hub_control,
+};
+
+static const struct pci_device_id uhci_pci_ids[] = { {
+        /* handle any USB UHCI controller */
+        PCI_DEVICE_CLASS(((PCI_CLASS_SERIAL_USB << 8) | 0x00), ~0),
+        .driver_data =  (unsigned long) &uhci_driver,
+        }, { /* end: all zeroes */ }
+};
+
+MODULE_DEVICE_TABLE(pci, uhci_pci_ids);
+
+static struct pci_driver uhci_pci_driver = {
+        .name =         (char *)hcd_name,
+        .id_table =     uhci_pci_ids,
+
+        .probe =        usb_hcd_pci_probe,
+        .remove =       usb_hcd_pci_remove,
+
+#ifdef  CONFIG_PM
+        .suspend =      usb_hcd_pci_suspend,
+        .resume =       usb_hcd_pci_resume,
+#endif  /* PM */
+};
+ 
+static int __init uhci_hcd_init(void)
+{
+        int retval = -ENOMEM;
+
+        printk(KERN_INFO DRIVER_DESC " " DRIVER_VERSION "\n");
+
+        if (usb_disabled())
+                return -ENODEV;
+
+        if (debug) {
+                errbuf = kmalloc(ERRBUF_LEN, GFP_KERNEL);
+                if (!errbuf)
+                        goto errbuf_failed;
+        }
+
+        uhci_debugfs_root = debugfs_create_dir("uhci", NULL);
+        if (!uhci_debugfs_root)
+                goto debug_failed;
+
+        uhci_up_cachep = kmem_cache_create("uhci_urb_priv",
+                sizeof(struct urb_priv), 0, 0, NULL, NULL);
+        if (!uhci_up_cachep)
+                goto up_failed;
+
+        retval = pci_register_driver(&uhci_pci_driver);
+        if (retval)
+                goto init_failed;
+
+        return 0;
+
+init_failed:
+        if (kmem_cache_destroy(uhci_up_cachep))
+                warn("not all urb_priv's were freed!");
+
+up_failed:
+        debugfs_remove(uhci_debugfs_root);
+
+debug_failed:
+        if (errbuf)
+                kfree(errbuf);
+
+errbuf_failed:
+
+        return retval;
+}
+
+static void __exit uhci_hcd_cleanup(void) 
+{
+        pci_unregister_driver(&uhci_pci_driver);
+        
+        if (kmem_cache_destroy(uhci_up_cachep))
+                warn("not all urb_priv's were freed!");
+
+        debugfs_remove(uhci_debugfs_root);
+
+        if (errbuf)
+                kfree(errbuf);
+}
+
+module_init(uhci_hcd_init);
+module_exit(uhci_hcd_cleanup);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");