RE: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

RE: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[Lu, Yinghai]

-----Original Message-----
From: Andi Kleen [mailto:ak@suse.de] 
Sent: Wednesday, December 06, 2006 9:31 AM

>Also for usb console keep should be made default because the output
won't
>be duplicated.

Still need to tx_read to make console can take command?

Or transfer to generic usb_serial or usb_debug that Greg just added with
console=ttyUSB0 to get tty? Then you still need to disable that
early_console sometime later.

YH

Re: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[Andi Kleen]

On Wednesday 06 December 2006 21:43, Lu, Yinghai wrote:
> -----Original Message-----
> From: Andi Kleen [mailto:ak@suse.de] 
> Sent: Wednesday, December 06, 2006 9:31 AM
> 
> >Also for usb console keep should be made default because the output
> won't
> >be duplicated.
> 
> Still need to tx_read to make console can take command?
> 
> Or transfer to generic usb_serial 

I think the protocols are incompatible? 

> or usb_debug that Greg just added 

Ah I didn't notice that. If there is a usb_debug that works later
then yes it would need to be disabled.

However I see a certain advantage to keep using the early 
usb console because it doesn't need any interrupts. So when the 
kernel is very confused after an oops it might have a higher
chance to still get the oops out.

I haven't looked how the other usb_debug works -- if it's polled
too then it wouldn't have much advantage.

Ok one advantage of a non early usb_debug is that it will properly use pci 
config space locking. The early implementation just ignores the port cf8 
lock which might lead to corruption later. That's ok after
an oops, but during normal output it can actually lead to
data corruption if it interferes with somebody else's config write.
Also on some systems cf8 is broken and doesn't work.

Disadvantage of using the locks of course is that it can deadlock
if an oops happen inside the critical region. So they might need
to be added to bust_spinlocks()

And it would be good if the late usb_debug still wouldn't rely
on interrupts.

But I agree it's probably better to transition to another usb_debug
console and not do keep by default.

-Andi

Re: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[Eric W. Biederman]

Andi Kleen <ak@suse.de> writes:

> On Wednesday 06 December 2006 21:43, Lu, Yinghai wrote:
>> -----Original Message-----
>> From: Andi Kleen [mailto:ak@suse.de] 
>> Sent: Wednesday, December 06, 2006 9:31 AM
>> 
>> >Also for usb console keep should be made default because the output
>> won't
>> >be duplicated.
>> 
>> Still need to tx_read to make console can take command?
>> 
>> Or transfer to generic usb_serial 
>
> I think the protocols are incompatible? 
>
>> or usb_debug that Greg just added 
>
> Ah I didn't notice that. If there is a usb_debug that works later
> then yes it would need to be disabled.
>
> However I see a certain advantage to keep using the early 
> usb console because it doesn't need any interrupts. So when the 
> kernel is very confused after an oops it might have a higher
> chance to still get the oops out.
>
> I haven't looked how the other usb_debug works -- if it's polled
> too then it wouldn't have much advantage.
>
> Ok one advantage of a non early usb_debug is that it will properly use pci 
> config space locking. The early implementation just ignores the port cf8 
> lock which might lead to corruption later. That's ok after
> an oops, but during normal output it can actually lead to
> data corruption if it interferes with somebody else's config write.
> Also on some systems cf8 is broken and doesn't work.
>
> Disadvantage of using the locks of course is that it can deadlock
> if an oops happen inside the critical region. So they might need
> to be added to bust_spinlocks()
>
> And it would be good if the late usb_debug still wouldn't rely
> on interrupts.
>
> But I agree it's probably better to transition to another usb_debug
> console and not do keep by default.

The only use of the early pci code is for finding the hardware.  Everything
else is through mmio.

The practical issue is that during the normal initialization of the ehci 
the reset of the hardware state is going to remove the delegation to the
ehci debug registers.

Greg's current thing uses the hardware but through the normal interrupt
driven usb methods.  I think it is worth using the ehci debug registers
if possible as that (except for reset) gives us independent control of
what is going on.

For understanding what needs to happen except for the initialization just
look at my dbgp_bulk_write routine.  That and the functions it call is
the only code in there that is executed.  It is just a hair more complicated
than other early debug port code because it has to deal with retransmits.
But I think it is still under 100 lines of code.


Eric

Re: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[David Brownell]

> > or usb_debug that Greg just added 
>
> Ah I didn't notice that. If there is a usb_debug that works later
> then yes it would need to be disabled.

I detect confusion here ... remember that there are potentially two
distinct Linux systems involved here:

  - Target, with some kind of console hooked up to the debug device;
    runs this _new_ "early debug port" code.

  - Host, to which that console connects (through the debug device);
    runs usb_debug, much like any other usb-serial device

It's analagous to debugging an embedded box using a serial console
with a Linux host ... except the target here is a PC, not an ARM
(or PPC, MIPS, etc) custom board.


Once the coexistence issues between the debug port and normal EHCI
driver get worked, there's no reason not to keep using that debug
port as a system console.  Heck, being able to do that might be a
huge win with some of the nasty suspend/resume problems we've got.

- Dave

Re: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[Andi Kleen]

\
>   - Host, to which that console connects (through the debug device);
>     runs usb_debug, much like any other usb-serial device

My understanding was that the client could run in user 
space only on top of libusb.

> 
> It's analagous to debugging an embedded box using a serial console
> with a Linux host ... except the target here is a PC, not an ARM
> (or PPC, MIPS, etc) custom board.
> 
> 
> Once the coexistence issues between the debug port and normal EHCI
> driver get worked, there's no reason not to keep using that debug
> port as a system console.  

One reason is the one I covered in my last mail -- locking of the PCI
type 1 ports.

However I suppose it would be ok to switch Eric's code between early
pci access and locked one once the PCI subsystem is up and running.
Just don't forget bust_spinlocks()

-Andi

Re: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[Eric W. Biederman]

Andi Kleen <ak@suse.de> writes:

> \
>>   - Host, to which that console connects (through the debug device);
>>     runs usb_debug, much like any other usb-serial device
>
> My understanding was that the client could run in user 
> space only on top of libusb.

Looks like a normal serial port with greg's patch.
I still need to try it though.

> One reason is the one I covered in my last mail -- locking of the PCI
> type 1 ports.
>
> However I suppose it would be ok to switch Eric's code between early
> pci access and locked one once the PCI subsystem is up and running.
> Just don't forget bust_spinlocks()

No pci access on that path.

Eric

Re: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[Andi Kleen]

> > However I suppose it would be ok to switch Eric's code between early
> > pci access and locked one once the PCI subsystem is up and running.
> > Just don't forget bust_spinlocks()
> 
> No pci access on that path.

Hmm good point. Ok ignore that then.

keep should be default then.

-Andi

Re: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[David Brownell]

On Wednesday 06 December 2006 1:24 pm, Andi Kleen wrote:
> >   - Host, to which that console connects (through the debug device);
> >     runs usb_debug, much like any other usb-serial device
> 
> My understanding was that the client could run in user 
> space only on top of libusb.

I suppose it could, if you didn't want to use it like a normal
serial consoe.


> > It's analagous to debugging an embedded box using a serial console
> > with a Linux host ... except the target here is a PC, not an ARM
> > (or PPC, MIPS, etc) custom board.
> > 
> > 
> > Once the coexistence issues between the debug port and normal EHCI
> > driver get worked, there's no reason not to keep using that debug
> > port as a system console.  
> 
> One reason is the one I covered in my last mail -- locking of the PCI
> type 1 ports.

That'd be part of coexistence.  The debug port is _designed_ to share
two different drivers like that ... EHCI can see, as it comes up,
whether the debug port is in use, and could then ignore it.  (At least,
unless/until the debug device gets removed.)

- Dave

RE: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[Lu, Yinghai]

-----Original Message-----
From: Andi Kleen [mailto:ak@suse.de] 
Sent: Wednesday, December 06, 2006 12:59 PM

>I haven't looked how the other usb_debug works -- if it's polled
>too then it wouldn't have much advantage.

Need to verify if the two sides of debug cable are identical. 

>And it would be good if the late usb_debug still wouldn't rely
>on interrupts.

Yes, esp. when usb can not get irq assigned correctly.

YH

Re: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[Andi Kleen]

On Tuesday 05 December 2006 12:01, Eric W. Biederman wrote:
> 
> Ok due to popular demands here is the slightly fixed patch that works
> on both i386 and x86_64.  For the i386 version you must not have
> HIGHMEM64G enabled. 
> 
> I just rolled it all into one patch as I'm to lazy to transmit all
> 3 of them.


You should definitely move the usb code to a separate file

Documentation/* needs to document the new option

Also for usb console keep should be made default because the output won't
be duplicated.


-Andi

Re: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[Eric W. Biederman]

David Brownell <david-b@pacbell.net> writes:

> On Sunday 03 December 2006 9:09 pm, Eric W. Biederman wrote:
>>
>> My driver should be sufficient to work with any EHCI in a realatively
>> clean state, and needs no special BIOS support just the hardware.
>> This appears to be different than the way the windows drivers are
>> using these debug devices.
>
> I'm glad to see someone finally got progress on this ... :)
>
> Separately, I forwarded some stuff I did last year ... maybe it'll help.
> You seem to have gotten further.  Have you also observed that the
> NetChip device seems to have polarity issues, such that only one
> end behaves properly?

I haven't yet.  But I don't think I have actually tried turning
the cable around in a very meaningful way yet either.  Possibly
this is something that has been fixed.  I know there are some
odd issues that I have encountered.  Like occasionally I would
need to stop the software on one side, or I would need to unplug
it when things got sufficiently confused.

> Note that this should **NOT** be specific to x86_64, since pretty
> much any PCI based EHCI can do this.  I wouldn't be able to use
> this on my NForce2 box, for example ...

So I took a quick look what it would take to do this truly generically
and even initializing this generally when console code typically
is registered looks like a problem.  Although only because we don't
get around to setting up pci_config space access helpers in a timely
manner.  To some extent that still sucks because you are still being
initialized before the general ehci-hcd code.

Regardless an arch specific i386 variant was easy to throw together.
It still needs a bit of work but it basically worked.

> As for EHCI registers, if this really _needs_ to live outside
> of drivers/usb/host, then I'd suggest <linux/usb/ehci.h> for
> the relevant declarations ... the <linux/usb/*.h> headers are
> provided exactly for sharing such declaration between otherwise
> unrelated parts of the tree.

Yep that sounds like the right thing to do.  I think I at least
need to be called from something outside of drivers/usb and may
need the code there.

Doing this in a truly generic fashion looks like a major pain.
Because all of the infrastructure needs to be fixed.

Eric

Re: [linux-usb-devel] [RFC][PATCH 0/2] x86_64 Early usb debug port support.

[Eric W. Biederman]

Ok due to popular demands here is the slightly fixed patch that works
on both i386 and x86_64.  For the i386 version you must not have
HIGHMEM64G enabled. 

I just rolled it all into one patch as I'm to lazy to transmit all
3 of them.

Eric

 arch/i386/kernel/head.S           |    8 +
 arch/x86_64/kernel/early_printk.c |  580 +++++++++++++++++++++++++++++++++++++
 arch/x86_64/kernel/head.S         |   11 +-
 drivers/usb/host/ehci.h           |    8 +
 include/asm-i386/fixmap.h         |    1 +
 include/asm-x86_64/fixmap.h       |    1 +
 6 files changed, 608 insertions(+), 1 deletions(-)

diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S
index ca31f18..f683565 100644
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -135,6 +135,12 @@ page_pde_offset = (__PAGE_OFFSET >> 20);
 	jb 10b
 	movl %edi,(init_pg_tables_end - __PAGE_OFFSET)
 
+	/* Do an early initialization of the fixmap area */
+	movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
+	movl $(swapper_pg_pmd - __PAGE_OFFSET), %eax
+	addl $0x007, %eax			/* 0x007 = PRESENT+RW+USER */
+	movl %eax, 4092(%edx)
+
 #ifdef CONFIG_SMP
 	xorl %ebx,%ebx				/* This is the boot CPU (BSP) */
 	jmp 3f
@@ -477,6 +483,8 @@ ENTRY(_stext)
 .section ".bss.page_aligned","w"
 ENTRY(swapper_pg_dir)
 	.fill 1024,4,0
+ENTRY(swapper_pg_pmd)
+	.fill 1024,4,0	
 ENTRY(empty_zero_page)
 	.fill 4096,1,0
 
diff --git a/arch/x86_64/kernel/early_printk.c b/arch/x86_64/kernel/early_printk.c
index d4050a5..71f2f88 100644
--- a/arch/x86_64/kernel/early_printk.c
+++ b/arch/x86_64/kernel/early_printk.c
@@ -3,9 +3,19 @@
 #include <linux/init.h>
 #include <linux/string.h>
 #include <linux/screen_info.h>
+#include <linux/usb_ch9.h>
+#include <linux/pci_regs.h>
+#include <linux/pci_ids.h>
+#include <linux/errno.h>
 #include <asm/io.h>
 #include <asm/processor.h>
 #include <asm/fcntl.h>
+#include <asm/pci-direct.h>
+#include <asm/pgtable.h>
+#include <asm/fixmap.h>
+#define EARLY_PRINTK
+#include "../../../drivers/usb/host/ehci.h"
+
 
 /* Simple VGA output */
 
@@ -155,6 +165,564 @@ static struct console early_serial_console = {
 	.index =	-1,
 };
 
+
+static struct ehci_caps __iomem *ehci_caps;
+static struct ehci_regs __iomem *ehci_regs;
+static struct ehci_dbg_port __iomem *ehci_debug;
+static unsigned dbgp_endpoint_out;
+
+#define USB_DEBUG_DEVNUM 127
+
+#define DBGP_DATA_TOGGLE	0x8800
+#define DBGP_PID_UPDATE(x, tok) \
+	((((x) ^ DBGP_DATA_TOGGLE) & 0xffff00) | ((tok) & 0xff))
+
+#define DBGP_LEN_UPDATE(x, len) (((x) & ~0x0f) | ((len) & 0x0f))
+/*
+ * USB Packet IDs (PIDs)
+ */
+
+/* token */
+#define USB_PID_OUT		0xe1
+#define USB_PID_IN		0x69
+#define USB_PID_SOF		0xa5
+#define USB_PID_SETUP		0x2d
+/* handshake */
+#define USB_PID_ACK		0xd2
+#define USB_PID_NAK		0x5a
+#define USB_PID_STALL		0x1e
+#define USB_PID_NYET		0x96
+/* data */
+#define USB_PID_DATA0		0xc3
+#define USB_PID_DATA1		0x4b
+#define USB_PID_DATA2		0x87
+#define USB_PID_MDATA		0x0f
+/* Special */
+#define USB_PID_PREAMBLE	0x3c
+#define USB_PID_ERR		0x3c
+#define USB_PID_SPLIT		0x78
+#define USB_PID_PING		0xb4
+#define USB_PID_UNDEF_0		0xf0
+
+#define USB_PID_DATA_TOGGLE	0x88
+#define DBGP_CLAIM (DBGP_OWNER | DBGP_ENABLED | DBGP_INUSE)
+
+#define PCI_CAP_ID_EHCI_DEBUG	0xa
+
+#define HUB_ROOT_RESET_TIME	50	/* times are in msec */
+#define HUB_SHORT_RESET_TIME	10
+#define HUB_LONG_RESET_TIME	200
+#define HUB_RESET_TIMEOUT	500
+
+#define DBGP_MAX_PACKET		8
+
+static int dbgp_wait_until_complete(void)
+{
+	unsigned ctrl;
+	for (;;) {
+		ctrl = readl(&ehci_debug->control);
+		/* Stop when the transaction is finished */
+		if (ctrl & DBGP_DONE)
+			break;
+	}
+	/* Now that we have observed the completed transaction,
+	 * clear the done bit.
+	 */
+	writel(ctrl | DBGP_DONE, &ehci_debug->control);
+	return (ctrl & DBGP_ERROR) ? -DBGP_ERRCODE(ctrl) : DBGP_LEN(ctrl);
+}
+
+static void dbgp_mdelay(int ms)
+{
+	int i;
+	while (ms--) {
+		for (i = 0; i < 1000; i++)
+			outb(0x1, 0x80);
+	}
+}
+
+static void dbgp_breath(void)
+{
+	/* Sleep to give the debug port a chance to breathe */
+}
+
+static int dbgp_wait_until_done(unsigned ctrl)
+{
+	unsigned pids, lpid;
+	int ret;
+
+retry:
+	writel(ctrl | DBGP_GO, &ehci_debug->control);
+	ret = dbgp_wait_until_complete();
+	pids = readl(&ehci_debug->pids);
+	lpid = DBGP_PID_GET(pids);
+
+	if (ret < 0)
+		return ret;
+
+	/* If the port is getting full or it has dropped data
+	 * start pacing ourselves, not necessary but it's friendly.
+	 */
+	if ((lpid == USB_PID_NAK) || (lpid == USB_PID_NYET))
+		dbgp_breath();
+	
+	/* If I get a NACK reissue the transmission */
+	if (lpid == USB_PID_NAK)
+		goto retry;
+
+	return ret;
+}
+
+static void dbgp_set_data(const void *buf, int size)
+{
+	const unsigned char *bytes = buf;
+	unsigned lo, hi;
+	int i;
+	lo = hi = 0;
+	for (i = 0; i < 4 && i < size; i++)
+		lo |= bytes[i] << (8*i);
+	for (; i < 8 && i < size; i++)
+		hi |= bytes[i] << (8*(i - 4));
+	writel(lo, &ehci_debug->data03);
+	writel(hi, &ehci_debug->data47);
+}
+
+static void dbgp_get_data(void *buf, int size)
+{
+	unsigned char *bytes = buf;
+	unsigned lo, hi;
+	int i;
+	lo = readl(&ehci_debug->data03);
+	hi = readl(&ehci_debug->data47);
+	for (i = 0; i < 4 && i < size; i++)
+		bytes[i] = (lo >> (8*i)) & 0xff;
+	for (; i < 8 && i < size; i++)
+		bytes[i] = (hi >> (8*(i - 4))) & 0xff;
+}
+
+static int dbgp_bulk_write(unsigned devnum, unsigned endpoint, const char *bytes, int size)
+{
+	unsigned pids, addr, ctrl;
+	int ret;
+	if (size > DBGP_MAX_PACKET)
+		return -1;
+
+	addr = DBGP_EPADDR(devnum, endpoint);
+
+	pids = readl(&ehci_debug->pids);
+	pids = DBGP_PID_UPDATE(pids, USB_PID_OUT);
+	
+	ctrl = readl(&ehci_debug->control);
+	ctrl = DBGP_LEN_UPDATE(ctrl, size);
+	ctrl |= DBGP_OUT;
+	ctrl |= DBGP_GO;
+
+	dbgp_set_data(bytes, size);
+	writel(addr, &ehci_debug->address);
+	writel(pids, &ehci_debug->pids);
+
+	ret = dbgp_wait_until_done(ctrl);
+	if (ret < 0) {
+		return ret;
+	}
+	return ret;
+}
+
+static int dbgp_bulk_read(unsigned devnum, unsigned endpoint, void *data, int size)
+{
+	unsigned pids, addr, ctrl;
+	int ret;
+
+	if (size > DBGP_MAX_PACKET)
+		return -1;
+
+	addr = DBGP_EPADDR(devnum, endpoint);
+
+	pids = readl(&ehci_debug->pids);
+	pids = DBGP_PID_UPDATE(pids, USB_PID_IN);
+		
+	ctrl = readl(&ehci_debug->control);
+	ctrl = DBGP_LEN_UPDATE(ctrl, size);
+	ctrl &= ~DBGP_OUT;
+	ctrl |= DBGP_GO;
+		
+	writel(addr, &ehci_debug->address);
+	writel(pids, &ehci_debug->pids);
+	ret = dbgp_wait_until_done(ctrl);
+	if (ret < 0)
+		return ret;
+	if (size > ret)
+		size = ret;
+	dbgp_get_data(data, size);
+	return ret;
+}
+
+static int dbgp_control_msg(unsigned devnum, int requesttype, int request, 
+	int value, int index, void *data, int size)
+{
+	unsigned pids, addr, ctrl;
+	struct usb_ctrlrequest req;
+	int read;
+	int ret;
+
+	read = (requesttype & USB_DIR_IN) != 0;
+	if (size > (read?DBGP_MAX_PACKET:0))
+		return -1;
+	
+	/* Compute the control message */
+	req.bRequestType = requesttype;
+	req.bRequest = request;
+	req.wValue = value;
+	req.wIndex = index;
+	req.wLength = size;
+
+	pids = DBGP_PID_SET(USB_PID_DATA0, USB_PID_SETUP);
+	addr = DBGP_EPADDR(devnum, 0);
+
+	ctrl = readl(&ehci_debug->control);
+	ctrl = DBGP_LEN_UPDATE(ctrl, sizeof(req));
+	ctrl |= DBGP_OUT;
+	ctrl |= DBGP_GO;
+
+	/* Send the setup message */
+	dbgp_set_data(&req, sizeof(req));
+	writel(addr, &ehci_debug->address);
+	writel(pids, &ehci_debug->pids);
+	ret = dbgp_wait_until_done(ctrl);
+	if (ret < 0)
+		return ret;
+
+
+	/* Read the result */
+	ret = dbgp_bulk_read(devnum, 0, data, size);
+	return ret;
+}
+
+
+/* Find a PCI capability */
+static __u32 __init find_cap(int num, int slot, int func, int cap) 
+{ 
+	u8 pos;
+	int bytes;
+	if (!(read_pci_config_16(num,slot,func,PCI_STATUS) & PCI_STATUS_CAP_LIST))
+		return 0;
+	pos = read_pci_config_byte(num,slot,func,PCI_CAPABILITY_LIST);
+	for (bytes = 0; bytes < 48 && pos >= 0x40; bytes++) { 
+		u8 id;
+		pos &= ~3; 
+		id = read_pci_config_byte(num,slot,func,pos+PCI_CAP_LIST_ID);
+		if (id == 0xff)
+			break;
+		if (id == cap) 
+			return pos; 
+		pos = read_pci_config_byte(num,slot,func,pos+PCI_CAP_LIST_NEXT); 
+	} 
+	return 0;
+} 
+
+static __u32 __init find_dbgp(int ehci_num, unsigned *rbus, unsigned *rslot, unsigned *rfunc)
+{
+	unsigned bus, slot, func;
+	
+	for (bus = 0; bus < 256; bus++) {
+		for (slot = 0; slot < 32; slot++) {
+			for (func = 0; func < 8; func++) {
+				u32 class;
+				unsigned cap;
+				class = read_pci_config(bus, slot, func, PCI_CLASS_REVISION);
+				if ((class >> 8) != PCI_CLASS_SERIAL_USB_EHCI)
+					continue;
+				cap = find_cap(bus, slot, func, PCI_CAP_ID_EHCI_DEBUG);
+				if (!cap)
+					continue;
+				if (ehci_num-- != 0)
+					continue;
+				*rbus = bus;
+				*rslot = slot;
+				*rfunc = func;
+				return cap;
+			}
+		}
+	}
+	return 0;
+}
+
+static int ehci_reset_port(int port)
+{
+	unsigned portsc;
+	unsigned delay_time, delay;
+
+	/* Reset the usb debug port */
+	portsc = readl(&ehci_regs->port_status[port - 1]);
+	portsc &= ~PORT_PE;
+	portsc |= PORT_RESET;
+	writel(portsc, &ehci_regs->port_status[port - 1]);
+
+	delay = HUB_ROOT_RESET_TIME;
+	for (delay_time = 0; delay_time < HUB_RESET_TIMEOUT;
+	     delay_time += delay) {
+		dbgp_mdelay(delay);
+
+		portsc = readl(&ehci_regs->port_status[port - 1]);
+		if (portsc & PORT_RESET) {
+			/* force reset to complete */
+			writel(portsc & ~(PORT_RWC_BITS | PORT_RESET), 
+				&ehci_regs->port_status[port - 1]);
+			while (portsc & PORT_RESET)
+				portsc = readl(&ehci_regs->port_status[port - 1]);
+		}
+
+		/* Device went away? */
+		if (!(portsc & PORT_CONNECT))
+			return -ENOTCONN;
+
+		/* bomb out completely if something weird happend */
+		if ((portsc & PORT_CSC))
+			return -EINVAL;
+
+		/* If we've finished resetting, then break out of the loop */
+		if (!(portsc & PORT_RESET) && (portsc & PORT_PE))
+			return 0;
+	}
+	return -EBUSY;
+}
+
+static int ehci_wait_for_port(int port)
+{
+	unsigned status;
+	int ret, reps;
+	for (reps = 0; reps >= 0; reps++) {
+		status = readl(&ehci_regs->status);
+		if (status & STS_PCD) {
+			ret = ehci_reset_port(port);
+			if (ret == 0)
+				return 0;
+		}
+	}
+	return -ENOTCONN;
+}
+
+
+#define DBGP_DEBUG 0
+#if DBGP_DEBUG
+void early_printk(const char *fmt, ...);
+# define dbgp_printk early_printk
+#else
+static inline void dbgp_printk(const char *fmt, ...) { }
+#endif
+
+static int ehci_setup(void)
+{
+	unsigned cmd, ctrl, status, portsc, hcs_params, debug_port, n_ports;
+	int ret;
+
+	hcs_params = readl(&ehci_caps->hcs_params);
+	debug_port = HCS_DEBUG_PORT(hcs_params);
+	n_ports    = HCS_N_PORTS(hcs_params);
+
+	dbgp_printk("debug_port: %d\n", debug_port);
+	dbgp_printk("n_ports:    %d\n", n_ports);
+
+	/* Reset the EHCI controller */
+	cmd = readl(&ehci_regs->command);
+	cmd |=CMD_RESET;
+	writel(cmd, &ehci_regs->command);
+	while (cmd & CMD_RESET)
+		cmd = readl(&ehci_regs->command);
+
+	/* Claim ownership, but do not enable yet */
+	ctrl = readl(&ehci_debug->control);
+	ctrl |= DBGP_OWNER;
+	ctrl &= ~(DBGP_ENABLED | DBGP_INUSE);
+	writel(ctrl, &ehci_debug->control);
+
+	/* Start the ehci running */
+	cmd = readl(&ehci_regs->command);
+	cmd &= ~(CMD_LRESET | CMD_IAAD | CMD_PSE | CMD_ASE | CMD_RESET);
+	cmd |= CMD_RUN;
+	writel(cmd, &ehci_regs->command);
+
+	/* Ensure everything is routed to the EHCI */
+	writel(FLAG_CF, &ehci_regs->configured_flag);
+
+	/* Wait until the controller is no longer halted */
+	do {
+		status = readl(&ehci_regs->status);
+	} while (status & STS_HALT);
+
+	/* Wait for a device to show up in the debug port */
+	ret = ehci_wait_for_port(debug_port);
+	if (ret < 0) {
+		dbgp_printk("No device found in debug port\n");
+		return -1;
+	}
+
+	/* Enable the debug port */
+	ctrl = readl(&ehci_debug->control);
+	ctrl |= DBGP_CLAIM;
+	writel(ctrl, &ehci_debug->control);
+	ctrl = readl(&ehci_debug->control);
+	if ((ctrl & DBGP_CLAIM) != DBGP_CLAIM) {
+		dbgp_printk("No device in debug port\n");
+		writel(ctrl & ~DBGP_CLAIM, &ehci_debug->control);
+		return -1;
+
+	}
+
+	/* Completely transfer the debug device to the debug controller */
+	portsc = readl(&ehci_regs->port_status[debug_port - 1]);
+	portsc &= ~PORT_PE;
+	writel(portsc, &ehci_regs->port_status[debug_port - 1]);
+
+	return 0;
+}
+
+static __init void early_dbgp_init(char *s)
+{
+	struct usb_debug_descriptor dbgp_desc;
+	void __iomem *ehci_bar;
+	unsigned ctrl, devnum;
+	unsigned bus, slot, func, cap;
+	unsigned debug_port, bar, offset;
+	unsigned bar_val;
+	unsigned dbgp_num;
+	char *e;
+	int ret;
+
+	if (!early_pci_allowed())
+		return;
+
+	dbgp_num = 0;
+	if (*s) {
+		dbgp_num = simple_strtoul(s, &e, 10);
+	}
+	dbgp_printk("dbgp_num: %d\n", dbgp_num);
+	cap = find_dbgp(dbgp_num, &bus, &slot, &func);
+	if (!cap)
+		return;
+
+	dbgp_printk("Found EHCI debug port\n");
+
+	debug_port = read_pci_config(bus, slot, func, cap);
+	bar = (debug_port >> 29) & 0x7;
+	bar = (bar * 4) + 0xc;
+	offset = (debug_port >> 16) & 0xfff;
+	dbgp_printk("bar: %02x offset: %03x\n", bar, offset);
+	if (bar != PCI_BASE_ADDRESS_0) {
+		dbgp_printk("only debug ports on bar 1 handled.\n");
+		return;
+	}
+
+	bar_val = read_pci_config(bus, slot, func, PCI_BASE_ADDRESS_0);
+	dbgp_printk("bar: %02x offset: %03x\n", bar, offset);
+	if (bar_val & ~PCI_BASE_ADDRESS_MEM_MASK) {
+		dbgp_printk("only simple 32bit mmio bars supported\n");
+		return;
+	}
+		
+
+	/* FIXME I don't have the bar size so just guess PAGE_SIZE is more
+	 * than enough.  1K is the biggest I have seen.
+	 */
+	dbgp_printk("dbgp pre-set_fixmap_nocache\n");
+	set_fixmap_nocache(FIX_DBGP_BASE, bar_val & PAGE_MASK);
+	dbgp_printk("dbgp post-set_fixmap_nocache\n");
+	ehci_bar = (void __iomem *)__fix_to_virt(FIX_DBGP_BASE);
+	ehci_bar += bar_val & ~PAGE_MASK;
+	dbgp_printk("ehci_bar: %p\n", ehci_bar);
+
+	ehci_caps  = ehci_bar;
+	ehci_regs  = ehci_bar + HC_LENGTH(readl(&ehci_caps->hc_capbase));
+	ehci_debug = ehci_bar + offset;
+
+	ret = ehci_setup();
+	if (ret < 0) {
+		dbgp_printk("ehci_setup failed\n");
+		return;
+	}
+
+	/* Find the debug device and make it device number 127 */
+	for (devnum = 0; devnum <= 127; devnum++) {
+		ret = dbgp_control_msg(devnum,
+			USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
+			USB_REQ_GET_DESCRIPTOR, (USB_DT_DEBUG << 8), 0,
+			&dbgp_desc, sizeof(dbgp_desc));
+		if (ret > 0)
+			break;
+	}
+	if (devnum > 127) {
+		dbgp_printk("Could not find attached debug device\n");
+		goto err;
+	}
+	if (ret < 0) {
+		dbgp_printk("Attached device is not a debug device\n");
+		goto err;
+	}
+	dbgp_endpoint_out = dbgp_desc.bDebugOutEndpoint;
+
+	/* Move the device to 127 if it isn't already there */
+	if (devnum != USB_DEBUG_DEVNUM) {
+		ret = dbgp_control_msg(devnum,
+			USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
+			USB_REQ_SET_ADDRESS, USB_DEBUG_DEVNUM, 0, NULL, 0);
+		if (ret < 0) {
+			dbgp_printk("Could not move attached device to %d\n", 
+				USB_DEBUG_DEVNUM);
+			goto err;
+		}
+		devnum = USB_DEBUG_DEVNUM;
+	}
+
+	/* Enable the debug interface */
+	ret = dbgp_control_msg(USB_DEBUG_DEVNUM,
+		USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
+		USB_REQ_SET_FEATURE, USB_DEVICE_DEBUG_MODE, 0, NULL, 0);
+	if (ret < 0) {
+		dbgp_printk(" Could not enable the debug device\n");
+		goto err;
+	}
+
+	/* Perform a small write to get the even/odd data state in sync
+	 */
+	ret = dbgp_bulk_write(USB_DEBUG_DEVNUM, dbgp_endpoint_out, " ",1);
+	if (ret < 0) {
+		dbgp_printk("dbgp_bulk_write failed: %d\n", ret);
+		goto err;
+	}
+
+
+	return;
+err:
+	/* Things didn't work so remove my claim */
+	ctrl = readl(&ehci_debug->control);
+	ctrl &= ~(DBGP_CLAIM | DBGP_OUT);
+	writel(ctrl, &ehci_debug->control);
+	return;
+}
+
+static void early_dbgp_write(struct console *con, const char *str, unsigned n)
+{
+	int chunk, ret;
+	if (!ehci_debug)
+		return;
+	while (n > 0) {
+		chunk = n;
+		if (chunk > DBGP_MAX_PACKET)
+			chunk = DBGP_MAX_PACKET;
+		ret = dbgp_bulk_write(USB_DEBUG_DEVNUM, 
+			dbgp_endpoint_out, str, chunk);
+		str += chunk;
+		n -= chunk;
+	}
+}
+
+static struct console early_dbgp_console = {
+	.name =		"earlydbg",
+	.write =	early_dbgp_write,
+	.flags = 	CON_PRINTBUFFER,
+	.index = 	-1,
+};
+
 /* Console interface to a host file on AMD's SimNow! */
 
 static int simnow_fd;
@@ -242,8 +810,20 @@ static int __init setup_early_printk(char *buf)
  		simnow_init(buf + 6);
  		early_console = &simnow_console;
  		keep_early = 1;
+	} else if (!strncmp(buf, "dbgp", 4)) {
+		early_dbgp_init(buf + 4);
+		early_console = &early_dbgp_console;
 	}
 	register_console(early_console);
+#if DBGP_DEBUG
+	{
+		static const char dbgp_test_str[] = 
+			"The quick brown fox jumped over the lazy dog!\n";
+		early_dbgp_init("");
+		early_dbgp_write(&early_dbgp_console, 
+			dbgp_test_str, sizeof(dbgp_test_str) - 1);
+	}
+#endif
 	return 0;
 }
 
diff --git a/arch/x86_64/kernel/head.S b/arch/x86_64/kernel/head.S
index 2f65469..4004965 100644
--- a/arch/x86_64/kernel/head.S
+++ b/arch/x86_64/kernel/head.S
@@ -271,7 +271,16 @@ NEXT_PAGE(level3_kernel_pgt)
 	.fill	510,8,0
 	/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
 	.quad	phys_level2_kernel_pgt | 0x007
-	.fill	1,8,0
+	.quad	phys_level2_fixmap_pgt | 0x007
+
+NEXT_PAGE(level2_fixmap_pgt)
+	.fill	506,8,0
+	.quad	phys_level1_fixmap_pgt | 0x007
+	/* 8MB reserved for vsyscalls + a 2MB hole = 4 + 1 entries */
+	.fill	5,8,0
+
+NEXT_PAGE(level1_fixmap_pgt)
+	.fill	512,8,0
 
 NEXT_PAGE(level2_ident_pgt)
 	/* 40MB for bootup. 	*/
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index bbc3082..0a67192 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -46,6 +46,7 @@ struct ehci_stats {
 
 #define	EHCI_MAX_ROOT_PORTS	15		/* see HCS_N_PORTS */
 
+#ifndef EARLY_PRINTK
 struct ehci_hcd {			/* one per controller */
 	/* glue to PCI and HCD framework */
 	struct ehci_caps __iomem *caps;
@@ -160,6 +161,7 @@ timer_action (struct ehci_hcd *ehci, enum ehci_timer_action action)
 		mod_timer (&ehci->watchdog, t);
 	}
 }
+#endif /* EARLY_PRINTK */
 
 /*-------------------------------------------------------------------------*/
 
@@ -384,6 +386,7 @@ union ehci_shadow {
  * These appear in both the async and (for interrupt) periodic schedules.
  */
 
+#ifndef EARLY_PRINTK
 struct ehci_qh {
 	/* first part defined by EHCI spec */
 	__le32			hw_next;	 /* see EHCI 3.6.1 */
@@ -432,6 +435,7 @@ struct ehci_qh {
 #define NO_FRAME ((unsigned short)~0)			/* pick new start */
 	struct usb_device	*dev;		/* access to TT */
 } __attribute__ ((aligned (32)));
+#endif /* EARLY_PRITNK */
 
 /*-------------------------------------------------------------------------*/
 
@@ -601,6 +605,8 @@ struct ehci_fstn {
 	union ehci_shadow	fstn_next;	/* ptr to periodic q entry */
 } __attribute__ ((aligned (32)));
 
+#ifndef EARLY_PRINTK
+
 /*-------------------------------------------------------------------------*/
 
 #ifdef CONFIG_USB_EHCI_ROOT_HUB_TT
@@ -659,4 +665,6 @@ ehci_port_speed(struct ehci_hcd *ehci, unsigned int portsc)
 
 /*-------------------------------------------------------------------------*/
 
+#endif /* EARLY_PRINTK */
+
 #endif /* __LINUX_EHCI_HCD_H */
diff --git a/include/asm-i386/fixmap.h b/include/asm-i386/fixmap.h
index 02428cb..ea08885 100644
--- a/include/asm-i386/fixmap.h
+++ b/include/asm-i386/fixmap.h
@@ -56,6 +56,7 @@ extern unsigned long __FIXADDR_TOP;
 enum fixed_addresses {
 	FIX_HOLE,
 	FIX_VDSO,
+	FIX_DBGP_BASE,
 #ifdef CONFIG_X86_LOCAL_APIC
 	FIX_APIC_BASE,	/* local (CPU) APIC) -- required for SMP or not */
 #endif
diff --git a/include/asm-x86_64/fixmap.h b/include/asm-x86_64/fixmap.h
index 1b620db..1f2978a 100644
--- a/include/asm-x86_64/fixmap.h
+++ b/include/asm-x86_64/fixmap.h
@@ -36,6 +36,7 @@ enum fixed_addresses {
 	VSYSCALL_LAST_PAGE,
 	VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
 	VSYSCALL_HPET,
+	FIX_DBGP_BASE,
 	FIX_HPET_BASE,
 	FIX_APIC_BASE,	/* local (CPU) APIC) -- required for SMP or not */
 	FIX_IO_APIC_BASE_0,