USB: net2280: update dma buffer allocation

[linux-2.6] / drivers / usb / host / ehci-hcd.c

/*
 * Copyright (c) 2000-2004 by David Brownell
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/pci.h>
#include <linux/dmapool.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/reboot.h>
#include <linux/usb.h>
#include <linux/moduleparam.h>
#include <linux/dma-mapping.h>

#include "../core/hcd.h"

#include <asm/byteorder.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/system.h>
#include <asm/unaligned.h>


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

/*
 * EHCI hc_driver implementation ... experimental, incomplete.
 * Based on the final 1.0 register interface specification.
 *
 * USB 2.0 shows up in upcoming www.pcmcia.org technology.
 * First was PCMCIA, like ISA; then CardBus, which is PCI.
 * Next comes "CardBay", using USB 2.0 signals.
 *
 * Contains additional contributions by Brad Hards, Rory Bolt, and others.
 * Special thanks to Intel and VIA for providing host controllers to
 * test this driver on, and Cypress (including In-System Design) for
 * providing early devices for those host controllers to talk to!
 *
 * HISTORY:
 *
 * 2004-05-10 Root hub and PCI suspend/resume support; remote wakeup. (db)
 * 2004-02-24 Replace pci_* with generic dma_* API calls (dsaxena@plexity.net)
 * 2003-12-29 Rewritten high speed iso transfer support (by Michal Sojka,
 *      <sojkam@centrum.cz>, updates by DB).
 *
 * 2002-11-29   Correct handling for hw async_next register.
 * 2002-08-06   Handling for bulk and interrupt transfers is mostly shared;
 *      only scheduling is different, no arbitrary limitations.
 * 2002-07-25   Sanity check PCI reads, mostly for better cardbus support,
 *      clean up HC run state handshaking.
 * 2002-05-24   Preliminary FS/LS interrupts, using scheduling shortcuts
 * 2002-05-11   Clear TT errors for FS/LS ctrl/bulk.  Fill in some other
 *      missing pieces:  enabling 64bit dma, handoff from BIOS/SMM.
 * 2002-05-07   Some error path cleanups to report better errors; wmb();
 *      use non-CVS version id; better iso bandwidth claim.
 * 2002-04-19   Control/bulk/interrupt submit no longer uses giveback() on
 *      errors in submit path.  Bugfixes to interrupt scheduling/processing.
 * 2002-03-05   Initial high-speed ISO support; reduce ITD memory; shift
 *      more checking to generic hcd framework (db).  Make it work with
 *      Philips EHCI; reduce PCI traffic; shorten IRQ path (Rory Bolt).
 * 2002-01-14   Minor cleanup; version synch.
 * 2002-01-08   Fix roothub handoff of FS/LS to companion controllers.
 * 2002-01-04   Control/Bulk queuing behaves.
 *
 * 2001-12-12   Initial patch version for Linux 2.5.1 kernel.
 * 2001-June    Works with usb-storage and NEC EHCI on 2.4
 */

#define DRIVER_VERSION "10 Dec 2004"
#define DRIVER_AUTHOR "David Brownell"
#define DRIVER_DESC "USB 2.0 'Enhanced' Host Controller (EHCI) Driver"

static const char       hcd_name [] = "ehci_hcd";


#undef EHCI_VERBOSE_DEBUG
#undef EHCI_URB_TRACE

#ifdef DEBUG
#define EHCI_STATS
#endif

/* magic numbers that can affect system performance */
#define EHCI_TUNE_CERR          3       /* 0-3 qtd retries; 0 == don't stop */
#define EHCI_TUNE_RL_HS         4       /* nak throttle; see 4.9 */
#define EHCI_TUNE_RL_TT         0
#define EHCI_TUNE_MULT_HS       1       /* 1-3 transactions/uframe; 4.10.3 */
#define EHCI_TUNE_MULT_TT       1
#define EHCI_TUNE_FLS           2       /* (small) 256 frame schedule */

#define EHCI_IAA_JIFFIES        (HZ/100)        /* arbitrary; ~10 msec */
#define EHCI_IO_JIFFIES         (HZ/10)         /* io watchdog > irq_thresh */
#define EHCI_ASYNC_JIFFIES      (HZ/20)         /* async idle timeout */
#define EHCI_SHRINK_JIFFIES     (HZ/200)        /* async qh unlink delay */

/* Initial IRQ latency:  faster than hw default */
static int log2_irq_thresh = 0;         // 0 to 6
module_param (log2_irq_thresh, int, S_IRUGO);
MODULE_PARM_DESC (log2_irq_thresh, "log2 IRQ latency, 1-64 microframes");

/* initial park setting:  slower than hw default */
static unsigned park = 0;
module_param (park, uint, S_IRUGO);
MODULE_PARM_DESC (park, "park setting; 1-3 back-to-back async packets");

#define INTR_MASK (STS_IAA | STS_FATAL | STS_PCD | STS_ERR | STS_INT)

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

#include "ehci.h"
#include "ehci-dbg.c"

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

/*
 * handshake - spin reading hc until handshake completes or fails
 * @ptr: address of hc register to be read
 * @mask: bits to look at in result of read
 * @done: value of those bits when handshake succeeds
 * @usec: timeout in microseconds
 *
 * Returns negative errno, or zero on success
 *
 * Success happens when the "mask" bits have the specified value (hardware
 * handshake done).  There are two failure modes:  "usec" have passed (major
 * hardware flakeout), or the register reads as all-ones (hardware removed).
 *
 * That last failure should_only happen in cases like physical cardbus eject
 * before driver shutdown. But it also seems to be caused by bugs in cardbus
 * bridge shutdown:  shutting down the bridge before the devices using it.
 */
static int handshake (void __iomem *ptr, u32 mask, u32 done, int usec)
{
        u32     result;

        do {
                result = readl (ptr);
                if (result == ~(u32)0)          /* card removed */
                        return -ENODEV;
                result &= mask;
                if (result == done)
                        return 0;
                udelay (1);
                usec--;
        } while (usec > 0);
        return -ETIMEDOUT;
}

/* force HC to halt state from unknown (EHCI spec section 2.3) */
static int ehci_halt (struct ehci_hcd *ehci)
{
        u32     temp = readl (&ehci->regs->status);

        /* disable any irqs left enabled by previous code */
        writel (0, &ehci->regs->intr_enable);

        if ((temp & STS_HALT) != 0)
                return 0;

        temp = readl (&ehci->regs->command);
        temp &= ~CMD_RUN;
        writel (temp, &ehci->regs->command);
        return handshake (&ehci->regs->status, STS_HALT, STS_HALT, 16 * 125);
}

/* put TDI/ARC silicon into EHCI mode */
static void tdi_reset (struct ehci_hcd *ehci)
{
        u32 __iomem     *reg_ptr;
        u32             tmp;

        reg_ptr = (u32 __iomem *)(((u8 __iomem *)ehci->regs) + 0x68);
        tmp = readl (reg_ptr);
        tmp |= 0x3;
        writel (tmp, reg_ptr);
}

/* reset a non-running (STS_HALT == 1) controller */
static int ehci_reset (struct ehci_hcd *ehci)
{
        int     retval;
        u32     command = readl (&ehci->regs->command);

        command |= CMD_RESET;
        dbg_cmd (ehci, "reset", command);
        writel (command, &ehci->regs->command);
        ehci_to_hcd(ehci)->state = HC_STATE_HALT;
        ehci->next_statechange = jiffies;
        retval = handshake (&ehci->regs->command, CMD_RESET, 0, 250 * 1000);

        if (retval)
                return retval;

        if (ehci_is_TDI(ehci))
                tdi_reset (ehci);

        return retval;
}

/* idle the controller (from running) */
static void ehci_quiesce (struct ehci_hcd *ehci)
{
        u32     temp;

#ifdef DEBUG
        if (!HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
                BUG ();
#endif

        /* wait for any schedule enables/disables to take effect */
        temp = readl (&ehci->regs->command) << 10;
        temp &= STS_ASS | STS_PSS;
        if (handshake (&ehci->regs->status, STS_ASS | STS_PSS,
                                temp, 16 * 125) != 0) {
                ehci_to_hcd(ehci)->state = HC_STATE_HALT;
                return;
        }

        /* then disable anything that's still active */
        temp = readl (&ehci->regs->command);
        temp &= ~(CMD_ASE | CMD_IAAD | CMD_PSE);
        writel (temp, &ehci->regs->command);

        /* hardware can take 16 microframes to turn off ... */
        if (handshake (&ehci->regs->status, STS_ASS | STS_PSS,
                                0, 16 * 125) != 0) {
                ehci_to_hcd(ehci)->state = HC_STATE_HALT;
                return;
        }
}

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

static void ehci_work(struct ehci_hcd *ehci, struct pt_regs *regs);

#include "ehci-hub.c"
#include "ehci-mem.c"
#include "ehci-q.c"
#include "ehci-sched.c"

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

static void ehci_watchdog (unsigned long param)
{
        struct ehci_hcd         *ehci = (struct ehci_hcd *) param;
        unsigned long           flags;

        spin_lock_irqsave (&ehci->lock, flags);

        /* lost IAA irqs wedge things badly; seen with a vt8235 */
        if (ehci->reclaim) {
                u32             status = readl (&ehci->regs->status);

                if (status & STS_IAA) {
                        ehci_vdbg (ehci, "lost IAA\n");
                        COUNT (ehci->stats.lost_iaa);
                        writel (STS_IAA, &ehci->regs->status);
                        ehci->reclaim_ready = 1;
                }
        }

        /* stop async processing after it's idled a bit */
        if (test_bit (TIMER_ASYNC_OFF, &ehci->actions))
                start_unlink_async (ehci, ehci->async);

        /* ehci could run by timer, without IRQs ... */
        ehci_work (ehci, NULL);

        spin_unlock_irqrestore (&ehci->lock, flags);
}

/* ehci_shutdown kick in for silicon on any bus (not just pci, etc).
 * This forcibly disables dma and IRQs, helping kexec and other cases
 * where the next system software may expect clean state.
 */
static void
ehci_shutdown (struct usb_hcd *hcd)
{
        struct ehci_hcd *ehci;

        ehci = hcd_to_ehci (hcd);
        (void) ehci_halt (ehci);

        /* make BIOS/etc use companion controller during reboot */
        writel (0, &ehci->regs->configured_flag);
}

static void ehci_port_power (struct ehci_hcd *ehci, int is_on)
{
        unsigned port;

        if (!HCS_PPC (ehci->hcs_params))
                return;

        ehci_dbg (ehci, "...power%s ports...\n", is_on ? "up" : "down");
        for (port = HCS_N_PORTS (ehci->hcs_params); port > 0; )
                (void) ehci_hub_control(ehci_to_hcd(ehci),
                                is_on ? SetPortFeature : ClearPortFeature,
                                USB_PORT_FEAT_POWER,
                                port--, NULL, 0);
        msleep(20);
}

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

/*
 * ehci_work is called from some interrupts, timers, and so on.
 * it calls driver completion functions, after dropping ehci->lock.
 */
static void ehci_work (struct ehci_hcd *ehci, struct pt_regs *regs)
{
        timer_action_done (ehci, TIMER_IO_WATCHDOG);
        if (ehci->reclaim_ready)
                end_unlink_async (ehci, regs);

        /* another CPU may drop ehci->lock during a schedule scan while
         * it reports urb completions.  this flag guards against bogus
         * attempts at re-entrant schedule scanning.
         */
        if (ehci->scanning)
                return;
        ehci->scanning = 1;
        scan_async (ehci, regs);
        if (ehci->next_uframe != -1)
                scan_periodic (ehci, regs);
        ehci->scanning = 0;

        /* the IO watchdog guards against hardware or driver bugs that
         * misplace IRQs, and should let us run completely without IRQs.
         * such lossage has been observed on both VT6202 and VT8235.
         */
        if (HC_IS_RUNNING (ehci_to_hcd(ehci)->state) &&
                        (ehci->async->qh_next.ptr != NULL ||
                         ehci->periodic_sched != 0))
                timer_action (ehci, TIMER_IO_WATCHDOG);
}

static void ehci_stop (struct usb_hcd *hcd)
{
        struct ehci_hcd         *ehci = hcd_to_ehci (hcd);

        ehci_dbg (ehci, "stop\n");

        /* Turn off port power on all root hub ports. */
        ehci_port_power (ehci, 0);

        /* no more interrupts ... */
        del_timer_sync (&ehci->watchdog);

        spin_lock_irq(&ehci->lock);
        if (HC_IS_RUNNING (hcd->state))
                ehci_quiesce (ehci);

        ehci_reset (ehci);
        writel (0, &ehci->regs->intr_enable);
        spin_unlock_irq(&ehci->lock);

        /* let companion controllers work when we aren't */
        writel (0, &ehci->regs->configured_flag);

        remove_debug_files (ehci);

        /* root hub is shut down separately (first, when possible) */
        spin_lock_irq (&ehci->lock);
        if (ehci->async)
                ehci_work (ehci, NULL);
        spin_unlock_irq (&ehci->lock);
        ehci_mem_cleanup (ehci);

#ifdef  EHCI_STATS
        ehci_dbg (ehci, "irq normal %ld err %ld reclaim %ld (lost %ld)\n",
                ehci->stats.normal, ehci->stats.error, ehci->stats.reclaim,
                ehci->stats.lost_iaa);
        ehci_dbg (ehci, "complete %ld unlink %ld\n",
                ehci->stats.complete, ehci->stats.unlink);
#endif

        dbg_status (ehci, "ehci_stop completed", readl (&ehci->regs->status));
}

/* one-time init, only for memory state */
static int ehci_init(struct usb_hcd *hcd)
{
        struct ehci_hcd         *ehci = hcd_to_ehci(hcd);
        u32                     temp;
        int                     retval;
        u32                     hcc_params;

        spin_lock_init(&ehci->lock);

        init_timer(&ehci->watchdog);
        ehci->watchdog.function = ehci_watchdog;
        ehci->watchdog.data = (unsigned long) ehci;

        /*
         * hw default: 1K periodic list heads, one per frame.
         * periodic_size can shrink by USBCMD update if hcc_params allows.
         */
        ehci->periodic_size = DEFAULT_I_TDPS;
        if ((retval = ehci_mem_init(ehci, GFP_KERNEL)) < 0)
                return retval;

        /* controllers may cache some of the periodic schedule ... */
        hcc_params = readl(&ehci->caps->hcc_params);
        if (HCC_ISOC_CACHE(hcc_params))         // full frame cache
                ehci->i_thresh = 8;
        else                                    // N microframes cached
                ehci->i_thresh = 2 + HCC_ISOC_THRES(hcc_params);

        ehci->reclaim = NULL;
        ehci->reclaim_ready = 0;
        ehci->next_uframe = -1;

        /*
         * dedicate a qh for the async ring head, since we couldn't unlink
         * a 'real' qh without stopping the async schedule [4.8].  use it
         * as the 'reclamation list head' too.
         * its dummy is used in hw_alt_next of many tds, to prevent the qh
         * from automatically advancing to the next td after short reads.
         */
        ehci->async->qh_next.qh = NULL;
        ehci->async->hw_next = QH_NEXT(ehci->async->qh_dma);
        ehci->async->hw_info1 = cpu_to_le32(QH_HEAD);
        ehci->async->hw_token = cpu_to_le32(QTD_STS_HALT);
        ehci->async->hw_qtd_next = EHCI_LIST_END;
        ehci->async->qh_state = QH_STATE_LINKED;
        ehci->async->hw_alt_next = QTD_NEXT(ehci->async->dummy->qtd_dma);

        /* clear interrupt enables, set irq latency */
        if (log2_irq_thresh < 0 || log2_irq_thresh > 6)
                log2_irq_thresh = 0;
        temp = 1 << (16 + log2_irq_thresh);
        if (HCC_CANPARK(hcc_params)) {
                /* HW default park == 3, on hardware that supports it (like
                 * NVidia and ALI silicon), maximizes throughput on the async
                 * schedule by avoiding QH fetches between transfers.
                 *
                 * With fast usb storage devices and NForce2, "park" seems to
                 * make problems:  throughput reduction (!), data errors...
                 */
                if (park) {
                        park = min(park, (unsigned) 3);
                        temp |= CMD_PARK;
                        temp |= park << 8;
                }
                ehci_dbg(ehci, "park %d\n", park);
        }
        if (HCC_PGM_FRAMELISTLEN(hcc_params)) {
                /* periodic schedule size can be smaller than default */
                temp &= ~(3 << 2);
                temp |= (EHCI_TUNE_FLS << 2);
                switch (EHCI_TUNE_FLS) {
                case 0: ehci->periodic_size = 1024; break;
                case 1: ehci->periodic_size = 512; break;
                case 2: ehci->periodic_size = 256; break;
                default:        BUG();
                }
        }
        ehci->command = temp;

        return 0;
}

/* start HC running; it's halted, ehci_init() has been run (once) */
static int ehci_run (struct usb_hcd *hcd)
{
        struct ehci_hcd         *ehci = hcd_to_ehci (hcd);
        int                     retval;
        u32                     temp;
        u32                     hcc_params;

        /* EHCI spec section 4.1 */
        if ((retval = ehci_reset(ehci)) != 0) {
                ehci_mem_cleanup(ehci);
                return retval;
        }
        writel(ehci->periodic_dma, &ehci->regs->frame_list);
        writel((u32)ehci->async->qh_dma, &ehci->regs->async_next);

        /*
         * hcc_params controls whether ehci->regs->segment must (!!!)
         * be used; it constrains QH/ITD/SITD and QTD locations.
         * pci_pool consistent memory always uses segment zero.
         * streaming mappings for I/O buffers, like pci_map_single(),
         * can return segments above 4GB, if the device allows.
         *
         * NOTE:  the dma mask is visible through dma_supported(), so
         * drivers can pass this info along ... like NETIF_F_HIGHDMA,
         * Scsi_Host.highmem_io, and so forth.  It's readonly to all
         * host side drivers though.
         */
        hcc_params = readl(&ehci->caps->hcc_params);
        if (HCC_64BIT_ADDR(hcc_params)) {
                writel(0, &ehci->regs->segment);
#if 0
// this is deeply broken on almost all architectures
                if (!dma_set_mask(hcd->self.controller, DMA_64BIT_MASK))
                        ehci_info(ehci, "enabled 64bit DMA\n");
#endif
        }


        // Philips, Intel, and maybe others need CMD_RUN before the
        // root hub will detect new devices (why?); NEC doesn't
        ehci->command &= ~(CMD_LRESET|CMD_IAAD|CMD_PSE|CMD_ASE|CMD_RESET);
        ehci->command |= CMD_RUN;
        writel (ehci->command, &ehci->regs->command);
        dbg_cmd (ehci, "init", ehci->command);

        /*
         * Start, enabling full USB 2.0 functionality ... usb 1.1 devices
         * are explicitly handed to companion controller(s), so no TT is
         * involved with the root hub.  (Except where one is integrated,
         * and there's no companion controller unless maybe for USB OTG.)
         */
        hcd->state = HC_STATE_RUNNING;
        writel (FLAG_CF, &ehci->regs->configured_flag);
        readl (&ehci->regs->command);   /* unblock posted writes */

        temp = HC_VERSION(readl (&ehci->caps->hc_capbase));
        ehci_info (ehci,
                "USB %x.%x started, EHCI %x.%02x, driver %s\n",
                ((ehci->sbrn & 0xf0)>>4), (ehci->sbrn & 0x0f),
                temp >> 8, temp & 0xff, DRIVER_VERSION);

        writel (INTR_MASK, &ehci->regs->intr_enable); /* Turn On Interrupts */

        /* GRR this is run-once init(), being done every time the HC starts.
         * So long as they're part of class devices, we can't do it init()
         * since the class device isn't created that early.
         */
        create_debug_files(ehci);

        return 0;
}

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

static irqreturn_t ehci_irq (struct usb_hcd *hcd, struct pt_regs *regs)
{
        struct ehci_hcd         *ehci = hcd_to_ehci (hcd);
        u32                     status;
        int                     bh;

        spin_lock (&ehci->lock);

        status = readl (&ehci->regs->status);

        /* e.g. cardbus physical eject */
        if (status == ~(u32) 0) {
                ehci_dbg (ehci, "device removed\n");
                goto dead;
        }

        status &= INTR_MASK;
        if (!status) {                  /* irq sharing? */
                spin_unlock(&ehci->lock);
                return IRQ_NONE;
        }

        /* clear (just) interrupts */
        writel (status, &ehci->regs->status);
        readl (&ehci->regs->command);   /* unblock posted write */
        bh = 0;

#ifdef  EHCI_VERBOSE_DEBUG
        /* unrequested/ignored: Frame List Rollover */
        dbg_status (ehci, "irq", status);
#endif

        /* INT, ERR, and IAA interrupt rates can be throttled */

        /* normal [4.15.1.2] or error [4.15.1.1] completion */
        if (likely ((status & (STS_INT|STS_ERR)) != 0)) {
                if (likely ((status & STS_ERR) == 0))
                        COUNT (ehci->stats.normal);
                else
                        COUNT (ehci->stats.error);
                bh = 1;
        }

        /* complete the unlinking of some qh [4.15.2.3] */
        if (status & STS_IAA) {
                COUNT (ehci->stats.reclaim);
                ehci->reclaim_ready = 1;
                bh = 1;
        }

        /* remote wakeup [4.3.1] */
        if (status & STS_PCD) {
                unsigned        i = HCS_N_PORTS (ehci->hcs_params);

                /* resume root hub? */
                status = readl (&ehci->regs->command);
                if (!(status & CMD_RUN))
                        writel (status | CMD_RUN, &ehci->regs->command);

                while (i--) {
                        int pstatus = readl (&ehci->regs->port_status [i]);

                        if (pstatus & PORT_OWNER)
                                continue;
                        if (!(pstatus & PORT_RESUME)
                                        || ehci->reset_done [i] != 0)
                                continue;

                        /* start 20 msec resume signaling from this port,
                         * and make khubd collect PORT_STAT_C_SUSPEND to
                         * stop that signaling.
                         */
                        ehci->reset_done [i] = jiffies + msecs_to_jiffies (20);
                        ehci_dbg (ehci, "port %d remote wakeup\n", i + 1);
                        usb_hcd_resume_root_hub(hcd);
                }
        }

        /* PCI errors [4.15.2.4] */
        if (unlikely ((status & STS_FATAL) != 0)) {
                /* bogus "fatal" IRQs appear on some chips... why?  */
                status = readl (&ehci->regs->status);
                dbg_cmd (ehci, "fatal", readl (&ehci->regs->command));
                dbg_status (ehci, "fatal", status);
                if (status & STS_HALT) {
                        ehci_err (ehci, "fatal error\n");
dead:
                        ehci_reset (ehci);
                        writel (0, &ehci->regs->configured_flag);
                        /* generic layer kills/unlinks all urbs, then
                         * uses ehci_stop to clean up the rest
                         */
                        bh = 1;
                }
        }

        if (bh)
                ehci_work (ehci, regs);
        spin_unlock (&ehci->lock);
        return IRQ_HANDLED;
}

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

/*
 * non-error returns are a promise to giveback() the urb later
 * we drop ownership so next owner (or urb unlink) can get it
 *
 * urb + dev is in hcd.self.controller.urb_list
 * we're queueing TDs onto software and hardware lists
 *
 * hcd-specific init for hcpriv hasn't been done yet
 *
 * NOTE:  control, bulk, and interrupt share the same code to append TDs
 * to a (possibly active) QH, and the same QH scanning code.
 */
static int ehci_urb_enqueue (
        struct usb_hcd  *hcd,
        struct usb_host_endpoint *ep,
        struct urb      *urb,
        gfp_t           mem_flags
) {
        struct ehci_hcd         *ehci = hcd_to_ehci (hcd);
        struct list_head        qtd_list;

        INIT_LIST_HEAD (&qtd_list);

        switch (usb_pipetype (urb->pipe)) {
        // case PIPE_CONTROL:
        // case PIPE_BULK:
        default:
                if (!qh_urb_transaction (ehci, urb, &qtd_list, mem_flags))
                        return -ENOMEM;
                return submit_async (ehci, ep, urb, &qtd_list, mem_flags);

        case PIPE_INTERRUPT:
                if (!qh_urb_transaction (ehci, urb, &qtd_list, mem_flags))
                        return -ENOMEM;
                return intr_submit (ehci, ep, urb, &qtd_list, mem_flags);

        case PIPE_ISOCHRONOUS:
                if (urb->dev->speed == USB_SPEED_HIGH)
                        return itd_submit (ehci, urb, mem_flags);
                else
                        return sitd_submit (ehci, urb, mem_flags);
        }
}

static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
{
        /* if we need to use IAA and it's busy, defer */
        if (qh->qh_state == QH_STATE_LINKED
                        && ehci->reclaim
                        && HC_IS_RUNNING (ehci_to_hcd(ehci)->state)) {
                struct ehci_qh          *last;

                for (last = ehci->reclaim;
                                last->reclaim;
                                last = last->reclaim)
                        continue;
                qh->qh_state = QH_STATE_UNLINK_WAIT;
                last->reclaim = qh;

        /* bypass IAA if the hc can't care */
        } else if (!HC_IS_RUNNING (ehci_to_hcd(ehci)->state) && ehci->reclaim)
                end_unlink_async (ehci, NULL);

        /* something else might have unlinked the qh by now */
        if (qh->qh_state == QH_STATE_LINKED)
                start_unlink_async (ehci, qh);
}

/* remove from hardware lists
 * completions normally happen asynchronously
 */

static int ehci_urb_dequeue (struct usb_hcd *hcd, struct urb *urb)
{
        struct ehci_hcd         *ehci = hcd_to_ehci (hcd);
        struct ehci_qh          *qh;
        unsigned long           flags;

        spin_lock_irqsave (&ehci->lock, flags);
        switch (usb_pipetype (urb->pipe)) {
        // case PIPE_CONTROL:
        // case PIPE_BULK:
        default:
                qh = (struct ehci_qh *) urb->hcpriv;
                if (!qh)
                        break;
                unlink_async (ehci, qh);
                break;

        case PIPE_INTERRUPT:
                qh = (struct ehci_qh *) urb->hcpriv;
                if (!qh)
                        break;
                switch (qh->qh_state) {
                case QH_STATE_LINKED:
                        intr_deschedule (ehci, qh);
                        /* FALL THROUGH */
                case QH_STATE_IDLE:
                        qh_completions (ehci, qh, NULL);
                        break;
                default:
                        ehci_dbg (ehci, "bogus qh %p state %d\n",
                                        qh, qh->qh_state);
                        goto done;
                }

                /* reschedule QH iff another request is queued */
                if (!list_empty (&qh->qtd_list)
                                && HC_IS_RUNNING (hcd->state)) {
                        int status;

                        status = qh_schedule (ehci, qh);
                        spin_unlock_irqrestore (&ehci->lock, flags);

                        if (status != 0) {
                                // shouldn't happen often, but ...
                                // FIXME kill those tds' urbs
                                err ("can't reschedule qh %p, err %d",
                                        qh, status);
                        }
                        return status;
                }
                break;

        case PIPE_ISOCHRONOUS:
                // itd or sitd ...

                // wait till next completion, do it then.
                // completion irqs can wait up to 1024 msec,
                break;
        }
done:
        spin_unlock_irqrestore (&ehci->lock, flags);
        return 0;
}

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

// bulk qh holds the data toggle

static void
ehci_endpoint_disable (struct usb_hcd *hcd, struct usb_host_endpoint *ep)
{
        struct ehci_hcd         *ehci = hcd_to_ehci (hcd);
        unsigned long           flags;
        struct ehci_qh          *qh, *tmp;

        /* ASSERT:  any requests/urbs are being unlinked */
        /* ASSERT:  nobody can be submitting urbs for this any more */

rescan:
        spin_lock_irqsave (&ehci->lock, flags);
        qh = ep->hcpriv;
        if (!qh)
                goto done;

        /* endpoints can be iso streams.  for now, we don't
         * accelerate iso completions ... so spin a while.
         */
        if (qh->hw_info1 == 0) {
                ehci_vdbg (ehci, "iso delay\n");
                goto idle_timeout;
        }

        if (!HC_IS_RUNNING (hcd->state))
                qh->qh_state = QH_STATE_IDLE;
        switch (qh->qh_state) {
        case QH_STATE_LINKED:
                for (tmp = ehci->async->qh_next.qh;
                                tmp && tmp != qh;
                                tmp = tmp->qh_next.qh)
                        continue;
                /* periodic qh self-unlinks on empty */
                if (!tmp)
                        goto nogood;
                unlink_async (ehci, qh);
                /* FALL THROUGH */
        case QH_STATE_UNLINK:           /* wait for hw to finish? */
idle_timeout:
                spin_unlock_irqrestore (&ehci->lock, flags);
                schedule_timeout_uninterruptible(1);
                goto rescan;
        case QH_STATE_IDLE:             /* fully unlinked */
                if (list_empty (&qh->qtd_list)) {
                        qh_put (qh);
                        break;
                }
                /* else FALL THROUGH */
        default:
nogood:
                /* caller was supposed to have unlinked any requests;
                 * that's not our job.  just leak this memory.
                 */
                ehci_err (ehci, "qh %p (#%02x) state %d%s\n",
                        qh, ep->desc.bEndpointAddress, qh->qh_state,
                        list_empty (&qh->qtd_list) ? "" : "(has tds)");
                break;
        }
        ep->hcpriv = NULL;
done:
        spin_unlock_irqrestore (&ehci->lock, flags);
        return;
}

static int ehci_get_frame (struct usb_hcd *hcd)
{
        struct ehci_hcd         *ehci = hcd_to_ehci (hcd);
        return (readl (&ehci->regs->frame_index) >> 3) % ehci->periodic_size;
}

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

#define DRIVER_INFO DRIVER_VERSION " " DRIVER_DESC

MODULE_DESCRIPTION (DRIVER_INFO);
MODULE_AUTHOR (DRIVER_AUTHOR);
MODULE_LICENSE ("GPL");

#ifdef CONFIG_PCI
#include "ehci-pci.c"
#define PCI_DRIVER              ehci_pci_driver
#endif

#ifdef CONFIG_MPC834x
#include "ehci-fsl.c"
#define PLATFORM_DRIVER         ehci_fsl_driver
#endif

#ifdef CONFIG_SOC_AU1200
#include "ehci-au1xxx.c"
#define PLATFORM_DRIVER         ehci_hcd_au1xxx_driver
#endif

#if !defined(PCI_DRIVER) && !defined(PLATFORM_DRIVER)
#error "missing bus glue for ehci-hcd"
#endif

static int __init ehci_hcd_init(void)
{
        int retval = 0;

        pr_debug("%s: block sizes: qh %Zd qtd %Zd itd %Zd sitd %Zd\n",
                 hcd_name,
                 sizeof(struct ehci_qh), sizeof(struct ehci_qtd),
                 sizeof(struct ehci_itd), sizeof(struct ehci_sitd));

#ifdef PLATFORM_DRIVER
        retval = platform_driver_register(&PLATFORM_DRIVER);
        if (retval < 0)
                return retval;
#endif

#ifdef PCI_DRIVER
        retval = pci_register_driver(&PCI_DRIVER);
        if (retval < 0) {
#ifdef PLATFORM_DRIVER
                platform_driver_unregister(&PLATFORM_DRIVER);
#endif
        }
#endif

        return retval;
}
module_init(ehci_hcd_init);

static void __exit ehci_hcd_cleanup(void)
{
#ifdef PLATFORM_DRIVER
        platform_driver_unregister(&PLATFORM_DRIVER);
#endif
#ifdef PCI_DRIVER
        pci_unregister_driver(&PCI_DRIVER);
#endif
}
module_exit(ehci_hcd_cleanup);