path: root/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/vmalloc.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/ktime.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/usb.h>
#include <linux/usb/hcd.h>
#include <linux/moduleparam.h>
#include <linux/dma-mapping.h>
#include <linux/debugfs.h>
#include <linux/slab.h>
#include <linux/uaccess.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!
 */

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

static const char	hcd_name [] = "ehci_hcd";


#undef 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
/*
 * Some drivers think it's safe to schedule isochronous transfers more than
 * 256 ms into the future (partly as a result of an old bug in the scheduling
 * code).  In an attempt to avoid trouble, we will use a minimum scheduling
 * length of 512 frames instead of 256.
 */
#define	EHCI_TUNE_FLS		1	/* (medium) 512-frame schedule */

#define EHCI_IAA_MSECS		10		/* arbitrary */
#define EHCI_IO_JIFFIES		(HZ/10)		/* io watchdog > irq_thresh */
#define EHCI_ASYNC_JIFFIES	(HZ/20)		/* async idle timeout */
#define EHCI_SHRINK_FRAMES	5		/* 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");

/* for flakey hardware, ignore overcurrent indicators */
static int ignore_oc = 0;
module_param (ignore_oc, bool, S_IRUGO);
MODULE_PARM_DESC (ignore_oc, "ignore bogus hardware overcurrent indications");

/* for link power management(LPM) feature */
static unsigned int hird;
module_param(hird, int, S_IRUGO);
MODULE_PARM_DESC(hird, "host initiated resume duration, +1 for each 75us\n");

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

/* for ASPM quirk of ISOC on AMD SB800 */
static struct pci_dev *amd_nb_dev;

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

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

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

static void
timer_action(struct ehci_hcd *ehci, enum ehci_timer_action action)
{
	/* Don't override timeouts which shrink or (later) disable
	 * the async ring; just the I/O watchdog.  Note that if a
	 * SHRINK were pending, OFF would never be requested.
	 */
	if (timer_pending(&ehci->watchdog)
			&& ((BIT(TIMER_ASYNC_SHRINK) | BIT(TIMER_ASYNC_OFF))
				& ehci->actions))
		return;

	if (!test_and_set_bit(action, &ehci->actions)) {
		unsigned long t;

		switch (action) {
		case TIMER_IO_WATCHDOG:
			if (!ehci->need_io_watchdog)
				return;
			t = EHCI_IO_JIFFIES;
			break;
		case TIMER_ASYNC_OFF:
			t = EHCI_ASYNC_JIFFIES;
			break;
		/* case TIMER_ASYNC_SHRINK: */
		default:
			/* add a jiffie since we synch against the
			 * 8 KHz uframe counter.
			 */
			t = DIV_ROUND_UP(EHCI_SHRINK_FRAMES * HZ, 1000) + 1;
			break;
		}
		mod_timer(&ehci->watchdog, t + jiffies);
	}
}

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

/*
 * 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 (struct ehci_hcd *ehci, void __iomem *ptr,
		      u32 mask, u32 done, int usec)
{
	u32	result;

	do {
		result = ehci_readl(ehci, 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 = ehci_readl(ehci, &ehci->regs->status);

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

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

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

static int handshake_on_error_set_halt(struct ehci_hcd *ehci, void __iomem *ptr,
				       u32 mask, u32 done, int usec)
{
	int error;

	error = handshake(ehci, ptr, mask, done, usec);
	if (error) {
		ehci_halt(ehci);
		ehci_to_hcd(ehci)->state = HC_STATE_HALT;
		ehci_err(ehci, "force halt; handshake %p %08x %08x -> %d\n",
			ptr, mask, done, error);
	}

	return error;
}

/* 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) + USBMODE);
	tmp = ehci_readl(ehci, reg_ptr);
	tmp |= USBMODE_CM_HC;
	/* The default byte access to MMR space is LE after
	 * controller reset. Set the required endian mode
	 * for transfer buffers to match the host microprocessor
	 */
	if (ehci_big_endian_mmio(ehci))
		tmp |= USBMODE_BE;
	ehci_writel(ehci, tmp, reg_ptr);
}

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

	/* If the EHCI debug controller is active, special care must be
	 * taken before and after a host controller reset */
	if (ehci->debug && !dbgp_reset_prep())
		ehci->debug = NULL;

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

	if (ehci->has_hostpc) {
		ehci_writel(ehci, USBMODE_EX_HC | USBMODE_EX_VBPS,
			(u32 __iomem *)(((u8 *)ehci->regs) + USBMODE_EX));
		ehci_writel(ehci, TXFIFO_DEFAULT,
			(u32 __iomem *)(((u8 *)ehci->regs) + TXFILLTUNING));
	}
	if (retval)
		return retval;

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

	if (ehci->debug)
		dbgp_external_startup();

	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 = ehci_readl(ehci, &ehci->regs->command) << 10;
	temp &= STS_ASS | STS_PSS;
	if (handshake_on_error_set_halt(ehci, &ehci->regs->status,
					STS_ASS | STS_PSS, temp, 16 * 125))
		return;

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

	/* hardware can take 16 microframes to turn off ... */
	handshake_on_error_set_halt(ehci, &ehci->regs->status,
				    STS_ASS | STS_PSS, 0, 16 * 125);
}

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

static void end_unlink_async(struct ehci_hcd *ehci);
static void ehci_work(struct ehci_hcd *ehci);

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

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

static void ehci_iaa_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 first with a vt8235.
	 * So we need this watchdog, but must protect it against both
	 * (a) SMP races against real IAA firing and retriggering, and
	 * (b) clean HC shutdown, when IAA watchdog was pending.
	 */
	if (ehci->reclaim
			&& !timer_pending(&ehci->iaa_watchdog)
			&& HC_IS_RUNNING(ehci_to_hcd(ehci)->state)) {
		u32 cmd, status;

		/* If we get here, IAA is *REALLY* late.  It's barely
		 * conceivable that the system is so busy that CMD_IAAD
		 * is still legitimately set, so let's be sure it's
		 * clear before we read STS_IAA.  (The HC should clear
		 * CMD_IAAD when it sets STS_IAA.)
		 */
		cmd = ehci_readl(ehci, &ehci->regs->command);
		if (cmd & CMD_IAAD)
			ehci_writel(ehci, cmd & ~CMD_IAAD,
					&ehci->regs->command);

		/* If IAA is set here it either legitimately triggered
		 * before we cleared IAAD above (but _way_ late, so we'll
		 * still count it as lost) ... or a silicon erratum:
		 * - VIA seems to set IAA without triggering the IRQ;
		 * - IAAD potentially cleared without setting IAA.
		 */
		status = ehci_readl(ehci, &ehci->regs->status);
		if ((status & STS_IAA) || !(cmd & CMD_IAAD)) {
			COUNT (ehci->stats.lost_iaa);
			ehci_writel(ehci, STS_IAA, &ehci->regs->status);
		}

		ehci_vdbg(ehci, "IAA watchdog: status %x cmd %x\n",
				status, cmd);
		end_unlink_async(ehci);
	}

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

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

	spin_lock_irqsave(&ehci->lock, flags);

	/* 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);

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

/* On some systems, leaving remote wakeup enabled prevents system shutdown.
 * The firmware seems to think that powering off is a wakeup event!
 * This routine turns off remote wakeup and everything else, on all ports.
 */
static void ehci_turn_off_all_ports(struct ehci_hcd *ehci)
{
	int	port = HCS_N_PORTS(ehci->hcs_params);

	while (port--)
		ehci_writel(ehci, PORT_RWC_BITS,
				&ehci->regs->port_status[port]);
}

/*
 * Halt HC, turn off all ports, and let the BIOS use the companion controllers.
 * Should be called with ehci->lock held.
 */
static void ehci_silence_controller(struct ehci_hcd *ehci)
{
	ehci_halt(ehci);
	ehci_turn_off_all_ports(ehci);

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

	/* unblock posted writes */
	ehci_readl(ehci, &ehci->regs->configured_flag);
}

/* 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 = hcd_to_ehci(hcd);

	del_timer_sync(&ehci->watchdog);
	del_timer_sync(&ehci->iaa_watchdog);

	spin_lock_irq(&ehci->lock);
	ehci_silence_controller(ehci);
	spin_unlock_irq(&ehci->lock);
}

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);
	/* Flush those writes */
	ehci_readl(ehci, &ehci->regs->command);
	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)
{
	timer_action_done (ehci, TIMER_IO_WATCHDOG);

	/* 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);
	if (ehci->next_uframe != -1)
		scan_periodic (ehci);
	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);
}

/*
 * Called when the ehci_hcd module is removed.
 */
static void ehci_stop (struct usb_hcd *hcd)
{
	struct ehci_hcd		*ehci = hcd_to_ehci (hcd);

	ehci_dbg (ehci, "stop\n");

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

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

	ehci_silence_controller(ehci);
	ehci_reset (ehci);
	spin_unlock_irq(&ehci->lock);

	remove_companion_file(ehci);
	remove_debug_files (ehci);

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

	if (amd_nb_dev) {
		pci_dev_put(amd_nb_dev);
		amd_nb_dev = NULL;
	}

#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",
		    ehci_readl(ehci, &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;
	struct ehci_qh_hw	*hw;

	spin_lock_init(&ehci->lock);

	/*
	 * keep io watchdog by default, those good HCDs could turn off it later
	 */
	ehci->need_io_watchdog = 1;
	init_timer(&ehci->watchdog);
	ehci->watchdog.function = ehci_watchdog;
	ehci->watchdog.data = (unsigned long) ehci;

	init_timer(&ehci->iaa_watchdog);
	ehci->iaa_watchdog.function = ehci_iaa_watchdog;
	ehci->iaa_watchdog.data = (unsigned long) ehci;

	hcc_params = ehci_readl(ehci, &ehci->caps->hcc_params);

	/*
	 * 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;
	INIT_LIST_HEAD(&ehci->cached_itd_list);
	INIT_LIST_HEAD(&ehci->cached_sitd_list);

	if (HCC_PGM_FRAMELISTLEN(hcc_params)) {
		/* periodic schedule size can be smaller than default */
		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();
		}
	}
	if ((retval = ehci_mem_init(ehci, GFP_KERNEL)) < 0)
		return retval;

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

	ehci->reclaim = NULL;
	ehci->next_uframe = -1;
	ehci->clock_frame = -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;
	hw = ehci->async->hw;
	hw->hw_next = QH_NEXT(ehci, ehci->async->qh_dma);
	hw->hw_info1 = cpu_to_hc32(ehci, QH_HEAD);
	hw->hw_token = cpu_to_hc32(ehci, QTD_STS_HALT);
	hw->hw_qtd_next = EHCI_LIST_END(ehci);
	ehci->async->qh_state = QH_STATE_LINKED;
	hw->hw_alt_next = QTD_NEXT(ehci, 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_PER_PORT_CHANGE_EVENT(hcc_params)) {
		ehci->has_ppcd = 1;
		ehci_dbg(ehci, "enable per-port change event\n");
		temp |= CMD_PPCEE;
	}
	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);
	}
	if (HCC_LPM(hcc_params)) {
		/* support link power management EHCI 1.1 addendum */
		ehci_dbg(ehci, "support lpm\n");
		ehci->has_lpm = 1;
		if (hird > 0xf) {
			ehci_dbg(ehci, "hird %d invalid, use default 0",
			hird);
			hird = 0;
		}
		temp |= hird << 24;
	}
	ehci->command = temp;

	/* Accept arbitrarily long scatter-gather lists */
	if (!(hcd->driver->flags & HCD_LOCAL_MEM))
		hcd->self.sg_tablesize = ~0;
	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;

	hcd->uses_new_polling = 1;

	/* EHCI spec section 4.1 */
	if ((retval = ehci_reset(ehci)) != 0) {
		ehci_mem_cleanup(ehci);
		return retval;
	}
	ehci_writel(ehci, ehci->periodic_dma, &ehci->regs->frame_list);
	ehci_writel(ehci, (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 = ehci_readl(ehci, &ehci->caps->hcc_params);
	if (HCC_64BIT_ADDR(hcc_params)) {
		ehci_writel(ehci, 0, &ehci->regs->segment);
#if 0
// this is deeply broken on almost all architectures
		if (!dma_set_mask(hcd->self.controller, DMA_BIT_MASK(64)))
			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;
	ehci_writel(ehci, 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.)
	 *
	 * Turning on the CF flag will transfer ownership of all ports
	 * from the companions to the EHCI controller.  If any of the
	 * companions are in the middle of a port reset at the time, it
	 * could cause trouble.  Write-locking ehci_cf_port_reset_rwsem
	 * guarantees that no resets are in progress.  After we set CF,
	 * a short delay lets the hardware catch up; new resets shouldn't
	 * be started before the port switching actions could complete.
	 */
	down_write(&ehci_cf_port_reset_rwsem);
	hcd->state = HC_STATE_RUNNING;
	ehci_writel(ehci, FLAG_CF, &ehci->regs->configured_flag);
	ehci_readl(ehci, &ehci->regs->command);	/* unblock posted writes */
	msleep(5);
	up_write(&ehci_cf_port_reset_rwsem);
	ehci->last_periodic_enable = ktime_get_real();

	temp = HC_VERSION(ehci_readl(ehci, &ehci->caps->hc_capbase));
	ehci_info (ehci,
		"USB %x.%x started, EHCI %x.%02x%s\n",
		((ehci->sbrn & 0xf0)>>4), (ehci->sbrn & 0x0f),
		temp >> 8, temp & 0xff,
		ignore_oc ? ", overcurrent ignored" : "");

	ehci_writel(ehci, 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);
	create_companion_file(ehci);

	return 0;
}

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

static irqreturn_t ehci_irq (struct usb_hcd *hcd)
{
	struct ehci_hcd		*ehci = hcd_to_ehci (hcd);
	u32			status, masked_status, pcd_status = 0, cmd;
	int			bh;

	spin_lock (&ehci->lock);

	status = ehci_readl(ehci, &ehci->regs->status);

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

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

	/* clear (just) interrupts */
	ehci_writel(ehci, masked_status, &ehci->regs->status);
	cmd = ehci_readl(ehci, &ehci->regs->command);
	bh = 0;

#ifdef	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) {
		/* guard against (alleged) silicon errata */
		if (cmd & CMD_IAAD) {
			ehci_writel(ehci, cmd & ~CMD_IAAD,
					&ehci->regs->command);
			ehci_dbg(ehci, "IAA with IAAD still set?\n");
		}
		if (ehci->reclaim) {
			COUNT(ehci->stats.reclaim);
			end_unlink_async(ehci);
		} else
			ehci_dbg(ehci, "IAA with nothing to reclaim?\n");
	}

	/* remote wakeup [4.3.1] */
	if (status & STS_PCD) {
		unsigned	i = HCS_N_PORTS (ehci->hcs_params);
		u32		ppcd = 0;

		/* kick root hub later */
		pcd_status = status;

		/* resume root hub? */
		if (!(cmd & CMD_RUN))
			usb_hcd_resume_root_hub(hcd);

		/* get per-port change detect bits */
		if (ehci->has_ppcd)
			ppcd = status >> 16;

		while (i--) {
			int pstatus;

			/* leverage per-port change bits feature */
			if (ehci->has_ppcd && !(ppcd & (1 << i)))
				continue;
			pstatus = ehci_readl(ehci,
					 &ehci->regs->port_status[i]);

			if (pstatus & PORT_OWNER)
				continue;
			if (!(test_bit(i, &ehci->suspended_ports) &&
					((pstatus & PORT_RESUME) ||
						!(pstatus & PORT_SUSPEND)) &&
					(pstatus & PORT_PE) &&
					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.  Use 5 ms extra for safety,
			 * like usb_port_resume() does.
			 */
			ehci->reset_done[i] = jiffies + msecs_to_jiffies(25);
			ehci_dbg (ehci, "port %d remote wakeup\n", i + 1);
			mod_timer(&hcd->rh_timer, ehci->reset_done[i]);
		}
	}

	/* PCI errors [4.15.2.4] */
	if (unlikely ((status & STS_FATAL) != 0)) {
		ehci_err(ehci, "fatal error\n");
		dbg_cmd(ehci, "fatal", cmd);
		dbg_status(ehci, "fatal", status);
		ehci_halt(ehci);
dead:
		ehci_reset(ehci);
		ehci_writel(ehci, 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);
	spin_unlock (&ehci->lock);
	if (pcd_status)
		usb_hcd_poll_rh_status(hcd);
	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 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:
		/* qh_completions() code doesn't handle all the fault cases
		 * in multi-TD control transfers.  Even 1KB is rare anyway.
		 */
		if (urb->transfer_buffer_length > (16 * 1024))
			return -EMSGSIZE;
		/* FALLTHROUGH */
	/* case PIPE_BULK: */
	default:
		if (!qh_urb_transaction (ehci, urb, &qtd_list, mem_flags))
			return -ENOMEM;
		return submit_async(ehci, urb, &qtd_list, mem_flags);

	case PIPE_INTERRUPT:
		if (!qh_urb_transaction (ehci, urb, &qtd_list, mem_flags))
			return -ENOMEM;
		return intr_submit(ehci, 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)
{
	/* failfast */
	if (!HC_IS_RUNNING(ehci_to_hcd(ehci)->state) && ehci->reclaim)
		end_unlink_async(ehci);

	/* If the QH isn't linked then there's nothing we can do
	 * unless we were called during a giveback, in which case
	 * qh_completions() has to deal with it.
	 */
	if (qh->qh_state != QH_STATE_LINKED) {
		if (qh->qh_state == QH_STATE_COMPLETING)
			qh->needs_rescan = 1;
		return;
	}

	/* defer till later if busy */
	if (ehci->reclaim) {
		struct ehci_qh		*last;

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

	/* start IAA cycle */
	} else
		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, int status)
{
	struct ehci_hcd		*ehci = hcd_to_ehci (hcd);
	struct ehci_qh		*qh;
	unsigned long		flags;
	int			rc;

	spin_lock_irqsave (&ehci->lock, flags);
	rc = usb_hcd_check_unlink_urb(hcd, urb, status);
	if (rc)
		goto done;

	switch (usb_pipetype (urb->pipe)) {
	// case PIPE_CONTROL:
	// case PIPE_BULK:
	default:
		qh = (struct ehci_qh *) urb->hcpriv;
		if (!qh)
			break;
		switch (qh->qh_state) {
		case QH_STATE_LINKED:
		case QH_STATE_COMPLETING:
			unlink_async(ehci, qh);
			break;
		case QH_STATE_UNLINK:
		case QH_STATE_UNLINK_WAIT:
			/* already started */
			break;
		case QH_STATE_IDLE:
			/* QH might be waiting for a Clear-TT-Buffer */
			qh_completions(ehci, qh);
			break;
		}
		break;

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

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

// 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 == NULL) {
		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:
	case QH_STATE_COMPLETING:
		for (tmp = ehci->async->qh_next.qh;
				tmp && tmp != qh;
				tmp = tmp->qh_next.qh)
			continue;
		/* periodic qh self-unlinks on empty, and a COMPLETING qh
		 * may already be unlinked.
		 */
		if (tmp)
			unlink_async(ehci, qh);
		/* FALL THROUGH */
	case QH_STATE_UNLINK:		/* wait for hw to finish? */
	case QH_STATE_UNLINK_WAIT:
idle_timeout:
		spin_unlock_irqrestore (&ehci->lock, flags);
		schedule_timeout_uninterruptible(1);
		goto rescan;
	case QH_STATE_IDLE:		/* fully unlinked */
		if (qh->clearing_tt)
			goto idle_timeout;
		if (list_empty (&qh->qtd_list)) {
			qh_put (qh);
			break;
		}
		/* else FALL THROUGH */
	default:
		/* 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 void
ehci_endpoint_reset(struct usb_hcd *hcd, struct usb_host_endpoint *ep)
{
	struct ehci_hcd		*ehci = hcd_to_ehci(hcd);
	struct ehci_qh		*qh;
	int			eptype = usb_endpoint_type(&ep->desc);
	int			epnum = usb_endpoint_num(&ep->desc);
	int			is_out = usb_endpoint_dir_out(&ep->desc);
	unsigned long		flags;

	if (eptype != USB_ENDPOINT_XFER_BULK && eptype != USB_ENDPOINT_XFER_INT)
		return;

	spin_lock_irqsave(&ehci->lock, flags);
	qh = ep->hcpriv;

	/* For Bulk and Interrupt endpoints we maintain the toggle state
	 * in the hardware; the toggle bits in udev aren't used at all.
	 * When an endpoint is reset by usb_clear_halt() we must reset
	 * the toggle bit in the QH.
	 */
	if (qh) {
		usb_settoggle(qh->dev, epnum, is_out, 0);
		if (!list_empty(&qh->qtd_list)) {
			WARN_ONCE(1, "clear_halt for a busy endpoint\n");
		} else if (qh->qh_state == QH_STATE_LINKED ||
				qh->qh_state == QH_STATE_COMPLETING) {

			/* The toggle value in the QH can't be updated
			 * while the QH is active.  Unlink it now;
			 * re-linking will call qh_refresh().
			 */
			if (eptype == USB_ENDPOINT_XFER_BULK)
				unlink_async(ehci, qh);
			else
				intr_deschedule(ehci, qh);
		}
	}
	spin_unlock_irqrestore(&ehci->lock, flags);
}

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

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

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

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

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

#ifdef CONFIG_USB_EHCI_MXC
#include "ehci-mxc.c"
#define PLATFORM_DRIVER		ehci_mxc_driver
#endif

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

#ifdef CONFIG_ARCH_OMAP3
#include "ehci-omap.c"
#define        PLATFORM_DRIVER         ehci_hcd_omap_driver
#endif

#ifdef CONFIG_PPC_PS3
#include "ehci-ps3.c"
#define	PS3_SYSTEM_BUS_DRIVER	ps3_ehci_driver
#endif

#ifdef CONFIG_USB_EHCI_HCD_PPC_OF
#include "ehci-ppc-of.c"
#define OF_PLATFORM_DRIVER	ehci_hcd_ppc_of_driver
#endif

#ifdef CONFIG_XPS_USB_HCD_XILINX
#include "ehci-xilinx-of.c"
#define XILINX_OF_PLATFORM_DRIVER	ehci_hcd_xilinx_of_driver
#endif

#ifdef CONFIG_PLAT_ORION
#include "ehci-orion.c"
#define	PLATFORM_DRIVER		ehci_orion_driver
#endif

#ifdef CONFIG_ARCH_IXP4XX
#include "ehci-ixp4xx.c"
#define	PLATFORM_DRIVER		ixp4xx_ehci_driver
#endif

#ifdef CONFIG_USB_W90X900_EHCI
#include "ehci-w90x900.c"
#define	PLATFORM_DRIVER		ehci_hcd_w90x900_driver
#endif

#ifdef CONFIG_ARCH_AT91
#include "ehci-atmel.c"
#define	PLATFORM_DRIVER		ehci_atmel_driver
#endif

#if !defined(PCI_DRIVER) && !defined(PLATFORM_DRIVER) && \
    !defined(PS3_SYSTEM_BUS_DRIVER) && !defined(OF_PLATFORM_DRIVER) && \
    !defined(XILINX_OF_PLATFORM_DRIVER)
#error "missing bus glue for ehci-hcd"
#endif

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

	if (usb_disabled())
		return -ENODEV;

	printk(KERN_INFO "%s: " DRIVER_DESC "\n", hcd_name);
	set_bit(USB_EHCI_LOADED, &usb_hcds_loaded);
	if (test_bit(USB_UHCI_LOADED, &usb_hcds_loaded) ||
			test_bit(USB_OHCI_LOADED, &usb_hcds_loaded))
		printk(KERN_WARNING "Warning! ehci_hcd should always be loaded"
				" before uhci_hcd and ohci_hcd, not after\n");

	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 DEBUG
	ehci_debug_root = debugfs_create_dir("ehci", usb_debug_root);
	if (!ehci_debug_root) {
		retval = -ENOENT;
		goto err_debug;
	}
#endif

#ifdef PLATFORM_DRIVER
	retval = platform_driver_register(&PLATFORM_DRIVER);
	if (retval < 0)
		goto clean0;
#endif

#ifdef PCI_DRIVER
	retval = pci_register_driver(&PCI_DRIVER);
	if (retval < 0)
		goto clean1;
#endif

#ifdef PS3_SYSTEM_BUS_DRIVER
	retval = ps3_ehci_driver_register(&PS3_SYSTEM_BUS_DRIVER);
	if (retval < 0)
		goto clean2;
#endif

#ifdef OF_PLATFORM_DRIVER
	retval = of_register_platform_driver(&OF_PLATFORM_DRIVER);
	if (retval < 0)
		goto clean3;
#endif

#ifdef XILINX_OF_PLATFORM_DRIVER
	retval = of_register_platform_driver(&XILINX_OF_PLATFORM_DRIVER);
	if (retval < 0)
		goto clean4;
#endif
	return retval;

#ifdef XILINX_OF_PLATFORM_DRIVER
	/* of_unregister_platform_driver(&XILINX_OF_PLATFORM_DRIVER); */
clean4:
#endif
#ifdef OF_PLATFORM_DRIVER
	of_unregister_platform_driver(&OF_PLATFORM_DRIVER);
clean3:
#endif
#ifdef PS3_SYSTEM_BUS_DRIVER
	ps3_ehci_driver_unregister(&PS3_SYSTEM_BUS_DRIVER);
clean2:
#endif
#ifdef PCI_DRIVER
	pci_unregister_driver(&PCI_DRIVER);
clean1:
#endif
#ifdef PLATFORM_DRIVER
	platform_driver_unregister(&PLATFORM_DRIVER);
clean0:
#endif
#ifdef DEBUG
	debugfs_remove(ehci_debug_root);
	ehci_debug_root = NULL;
err_debug:
#endif
	clear_bit(USB_EHCI_LOADED, &usb_hcds_loaded);
	return retval;
}
module_init(ehci_hcd_init);

static void __exit ehci_hcd_cleanup(void)
{
#ifdef XILINX_OF_PLATFORM_DRIVER
	of_unregister_platform_driver(&XILINX_OF_PLATFORM_DRIVER);
#endif
#ifdef OF_PLATFORM_DRIVER
	of_unregister_platform_driver(&OF_PLATFORM_DRIVER);
#endif
#ifdef PLATFORM_DRIVER
	platform_driver_unregister(&PLATFORM_DRIVER);
#endif
#ifdef PCI_DRIVER
	pci_unregister_driver(&PCI_DRIVER);
#endif
#ifdef PS3_SYSTEM_BUS_DRIVER
	ps3_ehci_driver_unregister(&PS3_SYSTEM_BUS_DRIVER);
#endif
#ifdef DEBUG
	debugfs_remove(ehci_debug_root);
#endif
	clear_bit(USB_EHCI_LOADED, &usb_hcds_loaded);
}
module_exit(ehci_hcd_cleanup);