path: root/config/grub/xhci/patches/0005-xhci/0006-grub-core-bus-usb-Add-xhci-support.patch

From fe3a0bce527e059e9121eb5ad2c3cc099f07a4bf Mon Sep 17 00:00:00 2001
From: Patrick Rudolph <patrick.rudolph@9elements.com>
Date: Sun, 15 Nov 2020 19:59:25 +0100
Subject: [PATCH 6/8] grub-core/bus/usb: Add xhci support

Add support for xHCI USB controllers.
The code is based on seabios implementation, but has been heavily
modified to match grubs internals.

Changes done in version 2:
* Code cleanup
* Code style fixes
* Don't leak memory buffers
* Compile without warnings
* Add more defines
* Add more helper functions
* Don't assume a 1:1 virtual to physical mapping
* Flush cachelines after writing buffers
* Don't use hardcoded page size
* Proper scratchpad register setup
* xHCI bios ownership handoff

Changes done in version 3:
* Fixed a race condition detecting events, which doesn't appear on
  qemu based xHCI controllers
* Don't accidently disable USB3.0 devices after first command
* Support arbitrary protocol speed IDs
* Coding style cleanup

Tested:
* Qemu system x86_64
  * virtual USB HID keyboard (usb-kbd)
  * virtual USB HID mass storage (usb-storage)
* init Supermicro X11SSH-F
  * iKVM HID keyboard
  * USB3 HID mass storage (controller root port)
  * USB HID keyboard

TODO:
  * Test on more hardware
  * Test on USB3 hubs
  * Support for USB 3.1 and USB 3.2 controllers

Tested on qemu using coreboot and grub as payload:

qemu-system-x86_64 -M q35 -bios $firmware -device qemu-xhci,id=xhci -accel kvm -m 1024M \
	-device usb-storage,drive=thumbdrive,bus=xhci.0,port=3 \
	-drive if=none,format=raw,id=thumbdrive,file=ubuntu-20.04.1-desktop-amd64.iso \
	-device usb-kbd,bus=xhci.0

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: sylv <sylv@sylv.io>
---
 Makefile.am                  |    2 +-
 grub-core/Makefile.core.def  |    7 +
 grub-core/bus/usb/xhci-pci.c |  195 +++
 grub-core/bus/usb/xhci.c     | 2496 ++++++++++++++++++++++++++++++++++
 include/grub/usb.h           |    4 +
 5 files changed, 2703 insertions(+), 1 deletion(-)
 create mode 100644 grub-core/bus/usb/xhci-pci.c
 create mode 100644 grub-core/bus/usb/xhci.c

diff --git a/Makefile.am b/Makefile.am
index 43635d5ff..65016f856 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -434,7 +434,7 @@ if COND_i386_coreboot
 FS_PAYLOAD_MODULES ?= $(shell cat grub-core/fs.lst)
 default_payload.elf: grub-mkstandalone grub-mkimage FORCE
 	test -f $@ && rm $@ || true
-	pkgdatadir=. ./grub-mkstandalone --grub-mkimage=./grub-mkimage -O i386-coreboot -o $@ --modules='ahci pata ehci uhci ohci usb_keyboard usbms part_msdos ext2 fat at_keyboard part_gpt usbserial_usbdebug cbfs' --install-modules='ls linux search configfile normal cbtime cbls memrw iorw minicmd lsmmap lspci halt reboot hexdump pcidump regexp setpci lsacpi chain test serial multiboot cbmemc linux16 gzio echo help syslinuxcfg xnu $(FS_PAYLOAD_MODULES) password_pbkdf2 $(EXTRA_PAYLOAD_MODULES)' --fonts= --themes= --locales= -d grub-core/ /boot/grub/grub.cfg=$(srcdir)/coreboot.cfg
+	pkgdatadir=. ./grub-mkstandalone --grub-mkimage=./grub-mkimage -O i386-coreboot -o $@ --modules='ahci pata xhci ehci uhci ohci usb_keyboard usbms part_msdos ext2 fat at_keyboard part_gpt usbserial_usbdebug cbfs' --install-modules='ls linux search configfile normal cbtime cbls memrw iorw minicmd lsmmap lspci halt reboot hexdump pcidump regexp setpci lsacpi chain test serial multiboot cbmemc linux16 gzio echo help syslinuxcfg xnu $(FS_PAYLOAD_MODULES) password_pbkdf2 $(EXTRA_PAYLOAD_MODULES)' --fonts= --themes= --locales= -d grub-core/ /boot/grub/grub.cfg=$(srcdir)/coreboot.cfg
 endif
 
 endif
diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index fb6078a34..64c3806ab 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -667,6 +667,13 @@ module = {
   enable = arm_coreboot;
 };
 
+module = {
+  name = xhci;
+  common = bus/usb/xhci.c;
+  pci = bus/usb/xhci-pci.c;
+  enable = pci;
+};
+
 module = {
   name = pci;
   common = bus/pci.c;
diff --git a/grub-core/bus/usb/xhci-pci.c b/grub-core/bus/usb/xhci-pci.c
new file mode 100644
index 000000000..a5bd3c97d
--- /dev/null
+++ b/grub-core/bus/usb/xhci-pci.c
@@ -0,0 +1,195 @@
+/* xhci.c - XHCI Support.  */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2020 9elements Cyber Security
+ *
+ *  GRUB 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 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/pci.h>
+#include <grub/cpu/pci.h>
+#include <grub/cs5536.h>
+#include <grub/misc.h>
+#include <grub/mm.h>
+#include <grub/time.h>
+#include <grub/usb.h>
+
+#define GRUB_XHCI_PCI_SBRN_REG  0x60
+#define GRUB_XHCI_ADDR_MEM_MASK	(~0xff)
+
+/* USBLEGSUP bits and related OS OWNED byte offset */
+enum
+{
+  GRUB_XHCI_BIOS_OWNED = (1 << 16),
+  GRUB_XHCI_OS_OWNED = (1 << 24)
+};
+
+/* PCI iteration function... */
+static int
+grub_xhci_pci_iter (grub_pci_device_t dev, grub_pci_id_t pciid,
+		    void *data __attribute__ ((unused)))
+{
+  volatile grub_uint32_t *regs;
+  grub_uint32_t base, base_h;
+  grub_uint32_t eecp_offset;
+  grub_uint32_t usblegsup = 0;
+  grub_uint64_t maxtime;
+  grub_uint32_t interf;
+  grub_uint32_t subclass;
+  grub_uint32_t class;
+  grub_uint8_t release;
+  grub_uint32_t class_code;
+
+  grub_dprintf ("xhci", "XHCI grub_xhci_pci_iter: begin\n");
+
+  if (pciid == GRUB_CS5536_PCIID)
+    {
+	grub_dprintf ("xhci", "CS5536 not supported\n");
+	return 0;
+    }
+  else
+    {
+      grub_pci_address_t addr;
+      addr = grub_pci_make_address (dev, GRUB_PCI_REG_CLASS);
+      class_code = grub_pci_read (addr) >> 8;
+      interf = class_code & 0xFF;
+      subclass = (class_code >> 8) & 0xFF;
+      class = class_code >> 16;
+
+      /* If this is not an XHCI controller, just return.  */
+      if (class != 0x0c || subclass != 0x03 || interf != 0x30)
+	return 0;
+
+      grub_dprintf ("xhci", "XHCI grub_xhci_pci_iter: class OK\n");
+
+      /* Check Serial Bus Release Number */
+      addr = grub_pci_make_address (dev, GRUB_XHCI_PCI_SBRN_REG);
+      release = grub_pci_read_byte (addr);
+      if (release != 0x30)
+	{
+	  grub_dprintf ("xhci", "XHCI grub_xhci_pci_iter: Wrong SBRN: %0x\n",
+			release);
+	  return 0;
+	}
+      grub_dprintf ("xhci", "XHCI grub_xhci_pci_iter: bus rev. num. OK\n");
+
+      /* Determine XHCI XHCC registers base address.  */
+      addr = grub_pci_make_address (dev, GRUB_PCI_REG_ADDRESS_REG0);
+      base = grub_pci_read (addr);
+      addr = grub_pci_make_address (dev, GRUB_PCI_REG_ADDRESS_REG1);
+      base_h = grub_pci_read (addr);
+      /* Stop if registers are mapped above 4G - GRUB does not currently
+       * work with registers mapped above 4G */
+      if (((base & GRUB_PCI_ADDR_MEM_TYPE_MASK) != GRUB_PCI_ADDR_MEM_TYPE_32)
+	  && (base_h != 0))
+	{
+	  grub_dprintf ("xhci",
+			"XHCI grub_xhci_pci_iter: registers above 4G are not supported\n");
+	  return 0;
+	}
+      base &= GRUB_PCI_ADDR_MEM_MASK;
+      if (!base)
+	{
+	  grub_dprintf ("xhci",
+			"XHCI: XHCI is not mapped\n");
+	  return 0;
+	}
+
+      /* Set bus master - needed for coreboot, VMware, broken BIOSes etc. */
+      addr = grub_pci_make_address (dev, GRUB_PCI_REG_COMMAND);
+      grub_pci_write_word(addr,
+			  GRUB_PCI_COMMAND_MEM_ENABLED
+			  | GRUB_PCI_COMMAND_BUS_MASTER
+			  | grub_pci_read_word(addr));
+
+      grub_dprintf ("xhci", "XHCI grub_xhci_pci_iter: 32-bit XHCI OK\n");
+    }
+
+  grub_dprintf ("xhci", "XHCI grub_xhci_pci_iter: iobase of XHCC: %08x\n",
+		(base & GRUB_XHCI_ADDR_MEM_MASK));
+
+  regs = grub_pci_device_map_range (dev,
+				    (base & GRUB_XHCI_ADDR_MEM_MASK),
+				    0x100);
+
+  /* Is there EECP ? */
+  eecp_offset = (grub_le_to_cpu32 (regs[2]) >> 8) & 0xff;
+
+    /* Determine and change ownership. */
+  /* EECP offset valid in HCCPARAMS */
+  /* Ownership can be changed via EECP only */
+  if (pciid != GRUB_CS5536_PCIID && eecp_offset >= 0x40)
+    {
+      grub_pci_address_t pciaddr_eecp;
+      pciaddr_eecp = grub_pci_make_address (dev, eecp_offset);
+
+      usblegsup = grub_pci_read (pciaddr_eecp);
+      if (usblegsup & GRUB_XHCI_BIOS_OWNED)
+	{
+	  grub_boot_time ("Taking ownership of XHCI controller");
+	  grub_dprintf ("xhci",
+			"XHCI grub_xhci_pci_iter: XHCI owned by: BIOS\n");
+	  /* Ownership change - set OS_OWNED bit */
+	  grub_pci_write (pciaddr_eecp, usblegsup | GRUB_XHCI_OS_OWNED);
+	  /* Ensure PCI register is written */
+	  grub_pci_read (pciaddr_eecp);
+
+	  /* Wait for finish of ownership change, XHCI specification
+	   * doesn't say how long it can take... */
+	  maxtime = grub_get_time_ms () + 1000;
+	  while ((grub_pci_read (pciaddr_eecp) & GRUB_XHCI_BIOS_OWNED)
+		 && (grub_get_time_ms () < maxtime));
+	  if (grub_pci_read (pciaddr_eecp) & GRUB_XHCI_BIOS_OWNED)
+	    {
+	      grub_dprintf ("xhci",
+			    "XHCI grub_xhci_pci_iter: XHCI change ownership timeout");
+	      /* Change ownership in "hard way" - reset BIOS ownership */
+	      grub_pci_write (pciaddr_eecp, GRUB_XHCI_OS_OWNED);
+	      /* Ensure PCI register is written */
+	      grub_pci_read (pciaddr_eecp);
+	    }
+	}
+      else if (usblegsup & GRUB_XHCI_OS_OWNED)
+	/* XXX: What to do in this case - nothing ? Can it happen ? */
+	grub_dprintf ("xhci", "XHCI grub_xhci_pci_iter: XHCI owned by: OS\n");
+      else
+	{
+	  grub_dprintf ("xhci",
+			"XHCI grub_Xhci_pci_iter: XHCI owned by: NONE\n");
+	  /* XXX: What to do in this case ? Can it happen ?
+	   * Is code below correct ? */
+	  /* Ownership change - set OS_OWNED bit */
+	  grub_pci_write (pciaddr_eecp, GRUB_XHCI_OS_OWNED);
+	  /* Ensure PCI register is written */
+	  grub_pci_read (pciaddr_eecp);
+	}
+
+      /* Disable SMI, just to be sure.  */
+      pciaddr_eecp = grub_pci_make_address (dev, eecp_offset + 4);
+      grub_pci_write (pciaddr_eecp, 0);
+      /* Ensure PCI register is written */
+      grub_pci_read (pciaddr_eecp);
+    }
+
+  grub_dprintf ("xhci", "inithw: XHCI grub_xhci_pci_iter: ownership OK\n");
+
+  grub_xhci_init_device (regs);
+  return 0;
+}
+
+void
+grub_xhci_pci_scan (void)
+{
+  grub_pci_iterate (grub_xhci_pci_iter, NULL);
+}
diff --git a/grub-core/bus/usb/xhci.c b/grub-core/bus/usb/xhci.c
new file mode 100644
index 000000000..f4591ffb5
--- /dev/null
+++ b/grub-core/bus/usb/xhci.c
@@ -0,0 +1,2496 @@
+/* xhci.c - XHCI Support.  */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2020 9elements Cyber Security
+ *
+ *  GRUB 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 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Big parts of this software are inspired by seabios XHCI implementation
+ * Released under LGPLv3. Credits to:
+ *
+ * Copyright (C) 2013  Gerd Hoffmann <kraxel@redhat.com>
+ * Copyright (C) 2014  Kevin O'Connor <kevin@koconnor.net>
+ */
+
+#include <grub/dl.h>
+#include <grub/err.h>
+#include <grub/mm.h>
+#include <grub/usb.h>
+#include <grub/usbtrans.h>
+#include <grub/misc.h>
+#include <grub/time.h>
+#include <grub/loader.h>
+#include <grub/disk.h>
+#include <grub/dma.h>
+#include <grub/cache.h>
+#include <grub/i386/cpuid.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+/* This simple GRUB implementation of XHCI driver */
+/* Based on the specification
+ * "eXtensible Host Controller Interface for Universal Serial Bus" Revision 1.2
+ */
+
+
+#define xhci_get_field(data, field)	     \
+    (((data) >> field##_SHIFT) & field##_MASK)
+#define XHCI_PORTSC_PLS_MASK     0xf
+#define XHCI_PORTSC_PLS_SHIFT    5
+#define XHCI_PORTSC_SPEED_MASK   0xf
+#define XHCI_PORTSC_SPEED_SHIFT  10
+
+enum
+{
+  XHCI_USB_FULLSPEED = 1,
+  XHCI_USB_LOWSPEED,
+  XHCI_USB_HIGHSPEED,
+  XHCI_USB_SUPERSPEED
+};
+
+/* Chapter 5.3 Host Controller Capability Registers */
+struct grub_xhci_caps {
+    grub_uint8_t  caplength;
+    grub_uint8_t  reserved_01;
+    grub_uint16_t hciversion;
+    grub_uint32_t hcsparams1;
+    grub_uint32_t hcsparams2;
+    grub_uint32_t hcsparams3;
+    grub_uint32_t hccparams;
+    grub_uint32_t dboff;
+    grub_uint32_t rtsoff;
+    grub_uint32_t hccparams2;
+} GRUB_PACKED;
+
+/* extended capabilities */
+struct grub_xhci_xcap {
+    grub_uint32_t cap;
+    grub_uint32_t data[];
+} GRUB_PACKED;
+
+#define XHCI_CAP_LEGACY_SUPPORT 1
+#define XHCI_CAP_SUPPORTED_PROTOCOL 2
+
+struct xhci_portmap {
+    grub_uint8_t start;
+    grub_uint8_t count;
+} GRUB_PACKED;
+
+struct grub_xhci_op {
+    grub_uint32_t usbcmd;
+    grub_uint32_t usbsts;
+    grub_uint32_t pagesize;
+    grub_uint32_t reserved_01[2];
+    grub_uint32_t dnctl;
+    grub_uint32_t crcr_low;
+    grub_uint32_t crcr_high;
+    grub_uint32_t reserved_02[4];
+    grub_uint32_t dcbaap_low;
+    grub_uint32_t dcbaap_high;
+    grub_uint32_t config;
+} GRUB_PACKED;
+
+enum
+{
+  GRUB_XHCI_CMD_RS = (1<<0),
+  GRUB_XHCI_CMD_HCRST = (1<<1),
+  GRUB_XHCI_CMD_INTE = (1<<2),
+  GRUB_XHCI_CMD_HSEE = (1<<3),
+  GRUB_XHCI_CMD_LHCRST = (1<<7),
+  GRUB_XHCI_CMD_CSS = (1<<8),
+  GRUB_XHCI_CMD_CRS = (1<<9),
+  GRUB_XHCI_CMD_EWE = (1<<10),
+  GRUB_XHCI_CMD_EU3S = (1<<11)
+};
+
+enum
+{
+  GRUB_XHCI_STS_HCH = (1<<0),
+  GRUB_XHCI_STS_HSE = (1<<2),
+  GRUB_XHCI_STS_EINT = (1<<3),
+  GRUB_XHCI_STS_PCD = (1<<4),
+  GRUB_XHCI_STS_SSS = (1<<8),
+  GRUB_XHCI_STS_RSS = (1<<9),
+  GRUB_XHCI_STS_SRE = (1<<10),
+  GRUB_XHCI_STS_CNR = (1<<11),
+  GRUB_XHCI_STS_HCE = (1<<12)
+};
+
+
+/* Port Registers Offset */
+#define GRUB_XHCI_PR_OFFSET 0x400
+/* Interrupter Registers Offset */
+#define GRUB_XHCI_IR_OFFSET 0x20
+
+/* Port Status and Control registers offsets */
+
+/* Chapter 6 Data Structures */
+#define ALIGN_SPBA 64
+#define ALIGN_DCBAA 64
+#define ALIGN_CMD_RING_SEG 64
+#define ALIGN_EVT_RING_SEG 64
+#define ALIGN_EVT_RING_TABLE 64
+#define ALIGN_TRB 16
+#define ALIGN_INCTX 64
+#define ALIGN_SLOTCTX 32
+
+#define BOUNDARY_RING 0x10000
+
+enum
+{
+  GRUB_XHCI_PORTSC_CCS = (1<<0),
+  GRUB_XHCI_PORTSC_PED = (1<<1),
+  GRUB_XHCI_PORTSC_OCA = (1<<3),
+  GRUB_XHCI_PORTSC_PR = (1<<4),
+  GRUB_XHCI_PORTSC_PP = (1<<9),
+  GRUB_XHCI_PORTSC_SPEED_FULL = (1<<10),
+  GRUB_XHCI_PORTSC_SPEED_LOW = (2<<10),
+  GRUB_XHCI_PORTSC_SPEED_HIGH = (3<<10),
+  GRUB_XHCI_PORTSC_SPEED_SUPER = (4<<10),
+  GRUB_XHCI_PORTSC_LWS = (1<<16),
+  GRUB_XHCI_PORTSC_CSC = (1<<17),
+  GRUB_XHCI_PORTSC_PEC = (1<<18),
+  GRUB_XHCI_PORTSC_WRC = (1<<19),
+  GRUB_XHCI_PORTSC_OCC = (1<<20),
+  GRUB_XHCI_PORTSC_PRC = (1<<21),
+  GRUB_XHCI_PORTSC_PLC = (1<<22),
+  GRUB_XHCI_PORTSC_CEC = (1<<23),
+  GRUB_XHCI_PORTSC_CAS = (1<<24),
+  GRUB_XHCI_PORTSC_WCE = (1<<25),
+  GRUB_XHCI_PORTSC_WDE = (1<<26),
+  GRUB_XHCI_PORTSC_WOE = (1<<27),
+  GRUB_XHCI_PORTSC_DR = (1<<30),
+  GRUB_XHCI_PORTSC_WPR = (1<<31)
+};
+
+/* XHCI memory data structs */
+#define GRUB_XHCI_MAX_ENDPOINTS 32
+
+#define GRUB_XHCI_RING_ITEMS 128
+#define GRUB_XHCI_RING_SIZE (GRUB_XHCI_RING_ITEMS*sizeof(struct grub_xhci_trb))
+/*
+ *  xhci_ring structs are allocated with XHCI_RING_SIZE alignment,
+ *  then we can get it from a trb pointer (provided by evt ring).
+ */
+#define XHCI_RING(_trb)	  \
+    ((struct grub_xhci_ring*)((grub_uint32_t)(_trb) & ~(GRUB_XHCI_RING_SIZE-1)))
+
+/* slot context */
+struct grub_xhci_slotctx {
+  grub_uint32_t ctx[4];
+  grub_uint32_t reserved_01[4];
+} GRUB_PACKED;
+
+/* endpoint context */
+struct grub_xhci_epctx {
+  grub_uint32_t ctx[2];
+  grub_uint32_t deq_low;
+  grub_uint32_t deq_high;
+  grub_uint32_t length;
+  grub_uint32_t reserved_01[3];
+} GRUB_PACKED;
+
+/* device context array element */
+struct grub_xhci_devlist {
+  grub_uint32_t ptr_low;
+  grub_uint32_t ptr_high;
+} GRUB_PACKED;
+
+/* input context */
+struct grub_xhci_inctx {
+  grub_uint32_t del;
+  grub_uint32_t add;
+  grub_uint32_t reserved_01[6];
+} GRUB_PACKED;
+
+/* transfer block (ring element) */
+struct grub_xhci_trb {
+  grub_uint32_t ptr_low;
+  grub_uint32_t ptr_high;
+  grub_uint32_t status;
+  grub_uint32_t control;
+} GRUB_PACKED;
+
+#define TRB_C	       (1<<0)
+#define TRB_TYPE_SHIFT	  10
+#define TRB_TYPE_MASK       0x3f
+#define TRB_TYPE(t)	 (((t) >> TRB_TYPE_SHIFT) & TRB_TYPE_MASK)
+
+#define TRB_EV_ED	   (1<<2)
+
+#define TRB_TR_ENT	  (1<<1)
+#define TRB_TR_ISP	  (1<<2)
+#define TRB_TR_NS	   (1<<3)
+#define TRB_TR_CH	   (1<<4)
+#define TRB_TR_IOC	  (1<<5)
+#define TRB_TR_IDT	  (1<<6)
+#define TRB_TR_TBC_SHIFT	7
+#define TRB_TR_TBC_MASK     0x3
+#define TRB_TR_BEI	  (1<<9)
+#define TRB_TR_TLBPC_SHIFT      16
+#define TRB_TR_TLBPC_MASK   0xf
+#define TRB_TR_FRAMEID_SHIFT    20
+#define TRB_TR_FRAMEID_MASK 0x7ff
+#define TRB_TR_SIA	  (1<<31)
+
+#define TRB_TR_DIR	  (1<<16)
+
+#define TRB_CR_SLOTID_SHIFT     24
+#define TRB_CR_SLOTID_MASK  0xff
+#define TRB_CR_EPID_SHIFT       16
+#define TRB_CR_EPID_MASK    0x1f
+
+#define TRB_CR_BSR	  (1<<9)
+#define TRB_CR_DC	   (1<<9)
+
+#define TRB_LK_TC	   (1<<1)
+
+#define TRB_INTR_SHIFT	  22
+#define TRB_INTR_MASK       0x3ff
+#define TRB_INTR(t)	 (((t).status >> TRB_INTR_SHIFT) & TRB_INTR_MASK)
+
+typedef enum TRBType {
+    TRB_RESERVED = 0,
+    TR_NORMAL,
+    TR_SETUP,
+    TR_DATA,
+    TR_STATUS,
+    TR_ISOCH,
+    TR_LINK,
+    TR_EVDATA,
+    TR_NOOP,
+    CR_ENABLE_SLOT,
+    CR_DISABLE_SLOT,
+    CR_ADDRESS_DEVICE,
+    CR_CONFIGURE_ENDPOINT,
+    CR_EVALUATE_CONTEXT,
+    CR_RESET_ENDPOINT,
+    CR_STOP_ENDPOINT,
+    CR_SET_TR_DEQUEUE,
+    CR_RESET_DEVICE,
+    CR_FORCE_EVENT,
+    CR_NEGOTIATE_BW,
+    CR_SET_LATENCY_TOLERANCE,
+    CR_GET_PORT_BANDWIDTH,
+    CR_FORCE_HEADER,
+    CR_NOOP,
+    ER_TRANSFER = 32,
+    ER_COMMAND_COMPLETE,
+    ER_PORT_STATUS_CHANGE,
+    ER_BANDWIDTH_REQUEST,
+    ER_DOORBELL,
+    ER_HOST_CONTROLLER,
+    ER_DEVICE_NOTIFICATION,
+    ER_MFINDEX_WRAP,
+} TRBType;
+
+typedef enum TRBCCode {
+    CC_INVALID = 0,
+    CC_SUCCESS,
+    CC_DATA_BUFFER_ERROR,
+    CC_BABBLE_DETECTED,
+    CC_USB_TRANSACTION_ERROR,
+    CC_TRB_ERROR,
+    CC_STALL_ERROR,
+    CC_RESOURCE_ERROR,
+    CC_BANDWIDTH_ERROR,
+    CC_NO_SLOTS_ERROR,
+    CC_INVALID_STREAM_TYPE_ERROR,
+    CC_SLOT_NOT_ENABLED_ERROR,
+    CC_EP_NOT_ENABLED_ERROR,
+    CC_SHORT_PACKET,
+    CC_RING_UNDERRUN,
+    CC_RING_OVERRUN,
+    CC_VF_ER_FULL,
+    CC_PARAMETER_ERROR,
+    CC_BANDWIDTH_OVERRUN,
+    CC_CONTEXT_STATE_ERROR,
+    CC_NO_PING_RESPONSE_ERROR,
+    CC_EVENT_RING_FULL_ERROR,
+    CC_INCOMPATIBLE_DEVICE_ERROR,
+    CC_MISSED_SERVICE_ERROR,
+    CC_COMMAND_RING_STOPPED,
+    CC_COMMAND_ABORTED,
+    CC_STOPPED,
+    CC_STOPPED_LENGTH_INVALID,
+    CC_MAX_EXIT_LATENCY_TOO_LARGE_ERROR = 29,
+    CC_ISOCH_BUFFER_OVERRUN = 31,
+    CC_EVENT_LOST_ERROR,
+    CC_UNDEFINED_ERROR,
+    CC_INVALID_STREAM_ID_ERROR,
+    CC_SECONDARY_BANDWIDTH_ERROR,
+    CC_SPLIT_TRANSACTION_ERROR
+} TRBCCode;
+
+enum {
+    PLS_U0	      =  0,
+    PLS_U1	      =  1,
+    PLS_U2	      =  2,
+    PLS_U3	      =  3,
+    PLS_DISABLED	=  4,
+    PLS_RX_DETECT       =  5,
+    PLS_INACTIVE	=  6,
+    PLS_POLLING	 =  7,
+    PLS_RECOVERY	=  8,
+    PLS_HOT_RESET       =  9,
+    PLS_COMPILANCE_MODE = 10,
+    PLS_TEST_MODE       = 11,
+    PLS_RESUME	  = 15,
+};
+
+/* event ring segment */
+struct grub_xhci_er_seg {
+  grub_uint32_t ptr_low;
+  grub_uint32_t ptr_high;
+  grub_uint32_t size;
+  grub_uint32_t reserved_01;
+} GRUB_PACKED;
+
+struct grub_xhci_ring {
+    struct grub_xhci_trb      ring[GRUB_XHCI_RING_ITEMS];
+    struct grub_xhci_trb      evt;
+    grub_uint32_t	     eidx;
+    grub_uint32_t	     nidx;
+    grub_uint32_t	     cs;
+};
+
+/* port registers */
+struct grub_xhci_pr {
+    grub_uint32_t portsc;
+    grub_uint32_t portpmsc;
+    grub_uint32_t portli;
+    grub_uint32_t reserved_01;
+} GRUB_PACKED;
+
+/* doorbell registers */
+struct grub_xhci_db {
+    grub_uint32_t doorbell;
+} GRUB_PACKED;
+
+/* runtime registers */
+struct grub_xhci_rts {
+    grub_uint32_t mfindex;
+} GRUB_PACKED;
+
+/* interrupter registers */
+struct grub_xhci_ir {
+    grub_uint32_t iman;
+    grub_uint32_t imod;
+    grub_uint32_t erstsz;
+    grub_uint32_t reserved_01;
+    grub_uint32_t erstba_low;
+    grub_uint32_t erstba_high;
+    grub_uint32_t erdp_low;
+    grub_uint32_t erdp_high;
+} GRUB_PACKED;
+
+struct grub_xhci_psid {
+	grub_uint8_t id;
+	grub_uint8_t psie;
+	grub_uint16_t psim;
+	grub_uint64_t bitrate;
+	grub_usb_speed_t grub_usb_speed;
+};
+
+struct grub_xhci_psids {
+	grub_uint8_t major;
+	grub_uint8_t minor;
+	struct grub_xhci_psid psids[16];
+};
+
+struct grub_xhci
+{
+  grub_uint8_t shutdown; /* 1 if preparing shutdown of controller */
+  /* xhci registers */
+  volatile struct grub_xhci_caps *caps;	/* Capability registers */
+  volatile struct grub_xhci_op *op;	/* Operational registers */
+  volatile struct grub_xhci_pr *pr;	/* Port Registers */
+  volatile struct grub_xhci_db *db;	/* doorbell */
+  volatile struct grub_xhci_ir *ir;	/* Interrupt Registers */
+  /* devinfo */
+  grub_uint32_t xcap;
+  grub_uint32_t ports;
+  grub_uint32_t slots;
+  grub_uint8_t flag64;
+  grub_uint16_t spb;
+  grub_uint32_t pagesize;
+  struct xhci_portmap usb2;
+  struct xhci_portmap usb3;
+  struct grub_xhci_psids *psids;
+  /* xhci data structures */
+  struct grub_pci_dma_chunk *devs_dma;
+  volatile struct grub_xhci_devlist *devs;
+  struct grub_pci_dma_chunk *cmds_dma;
+  volatile struct grub_xhci_ring *cmds;
+  struct grub_pci_dma_chunk *evts_dma;
+  volatile struct grub_xhci_ring *evts;
+  struct grub_pci_dma_chunk *eseg_dma;
+  volatile struct grub_xhci_er_seg *eseg;
+  struct grub_pci_dma_chunk *spba_dma;
+  struct grub_pci_dma_chunk *spad_dma;
+
+  struct grub_xhci *next;
+};
+
+struct grub_xhci_priv {
+  grub_uint8_t                    slotid;
+  grub_uint32_t                   max_packet;
+  struct grub_pci_dma_chunk       *enpoint_trbs_dma[32];
+  volatile struct grub_xhci_ring  *enpoint_trbs[32];
+  struct grub_pci_dma_chunk       *slotctx_dma;
+};
+
+struct grub_xhci_port {
+  grub_uint32_t portsc;
+  grub_uint32_t portpmsc;
+  grub_uint32_t portli;
+  grub_uint32_t reserved_01;
+};
+
+struct grub_xhci_transfer_controller_data {
+  grub_uint32_t transfer_size;
+};
+
+static struct grub_xhci *xhci;
+
+/****************************************************************
+ * general access functions
+ ****************************************************************/
+
+static inline void
+grub_xhci_write32(volatile void *addr, grub_uint32_t val) {
+    *(volatile grub_uint32_t *)addr = val;
+}
+static inline void
+grub_xhci_write16(volatile void *addr, grub_uint16_t val) {
+    *(volatile grub_uint16_t *)addr = val;
+}
+static inline void
+grub_xhci_write8(void *addr, grub_uint8_t val) {
+    *(volatile grub_uint8_t *)addr = val;
+}
+
+static inline grub_uint32_t
+grub_xhci_read32(volatile void *addr) {
+  return grub_le_to_cpu32 (*((volatile grub_uint32_t *)addr));
+}
+
+static inline grub_uint16_t
+grub_xhci_read16(volatile void *addr) {
+  return grub_le_to_cpu16 (*((volatile grub_uint32_t *)addr));
+}
+static inline grub_uint8_t
+grub_xhci_read8(volatile void *addr) {
+  return (*((volatile grub_uint32_t *)addr));
+}
+
+static inline grub_uint32_t
+grub_xhci_port_read (struct grub_xhci *x, grub_uint32_t port)
+{
+  return grub_xhci_read32(&x->pr[port].portsc);
+}
+
+static inline void
+grub_xhci_port_write (struct grub_xhci *x, grub_uint32_t port,
+		      grub_uint32_t and_mask, grub_uint32_t or_mask)
+{
+  grub_uint32_t reg = grub_xhci_port_read(x, port);
+  reg &= and_mask;
+  reg |= or_mask;
+
+  grub_xhci_write32(&x->pr[port].portsc, reg);
+}
+
+/****************************************************************
+ * xhci status and support functions
+ ****************************************************************/
+
+static grub_uint32_t xhci_get_pagesize(struct grub_xhci *x)
+{
+  /* Chapter 5.4.3 Page Size Register (PAGESIZE) */
+  for (grub_uint8_t i = 0; i < 16; i++)
+    {
+      if (grub_xhci_read32(&x->op->pagesize) & (1 << i))
+	return 1 << (12 + i);
+    }
+  return 0;
+}
+
+static grub_uint8_t xhci_is_halted(struct grub_xhci *x)
+{
+  return !!(grub_xhci_read32(&x->op->usbsts) & 1);
+}
+
+/* Just for debugging */
+static void xhci_check_status(struct grub_xhci *x)
+{
+  grub_uint32_t reg;
+
+  reg = grub_xhci_read32(&x->op->usbsts);
+  if (reg & 1)
+    grub_dprintf("xhci", "%s: xHCI halted\n", __func__);
+  if (reg & 2)
+    grub_dprintf("xhci", "%s: Host system error detected\n", __func__);
+  if (reg & (1 << 12))
+    grub_dprintf("xhci", "%s: Internal error detected\n", __func__);
+  reg = grub_xhci_read32(&x->op->crcr_low);
+  if (reg & (1 << 3))
+    grub_dprintf("xhci", "%s: Command ring running\n", __func__);
+}
+
+/* xhci_memalign_dma32 allocates DMA memory satisfying alignment and boundary
+ * requirements without wasting to much memory */
+static struct grub_pci_dma_chunk *
+xhci_memalign_dma32(grub_size_t align,
+		    grub_size_t size,
+		    grub_size_t boundary)
+{
+	struct grub_pci_dma_chunk *tmp;
+	const grub_uint32_t mask = boundary - 1;
+	grub_uint32_t start, end;
+
+	/* Allocate some memory and check if it doesn't cross boundary */
+	tmp = grub_memalign_dma32(align, size);
+	start = grub_dma_get_phys(tmp);
+	end = start + size - 1;
+	if ((start & mask) == (end & mask))
+		return tmp;
+	/* Buffer isn't usable, allocate bigger one */
+	grub_dma_free(tmp);
+
+	return grub_memalign_dma32(boundary, size);
+}
+
+/****************************************************************
+ * helper functions for in context DMA buffer
+ ****************************************************************/
+
+static int
+grub_xhci_inctx_size(struct grub_xhci *x)
+{
+  const grub_uint8_t cnt = GRUB_XHCI_MAX_ENDPOINTS + 1;
+  return (sizeof(struct grub_xhci_inctx) * cnt) << x->flag64;
+}
+
+static void
+grub_xhci_inctx_sync_dma_caches(struct grub_xhci *x, struct grub_pci_dma_chunk *inctx)
+{
+  grub_arch_sync_dma_caches(inctx, grub_xhci_inctx_size(x));
+}
+
+static struct grub_pci_dma_chunk *
+grub_xhci_alloc_inctx(struct grub_xhci *x, int maxepid,
+		      struct grub_usb_device *dev)
+{
+  int size = grub_xhci_inctx_size(x);
+  struct grub_pci_dma_chunk *dma = xhci_memalign_dma32(ALIGN_INCTX, size,
+						       x->pagesize);
+  if (!dma)
+    return NULL;
+
+  volatile struct grub_xhci_inctx *in = grub_dma_get_virt(dma);
+  grub_memset((void *)in, 0, size);
+
+  struct grub_xhci_slotctx *slot = (void*)&in[1 << x->flag64];
+  slot->ctx[0]    |= maxepid << 27; /* context entries */
+  grub_dprintf("xhci", "%s: speed=%d root_port=%d\n", __func__, dev->speed, dev->root_port);
+  switch (dev->speed) {
+    case GRUB_USB_SPEED_FULL:
+      slot->ctx[0]    |= XHCI_USB_FULLSPEED << 20;
+      break;
+    case GRUB_USB_SPEED_HIGH:
+     slot->ctx[0]     |= XHCI_USB_HIGHSPEED << 20;
+      break;
+    case GRUB_USB_SPEED_LOW:
+      slot->ctx[0]    |= XHCI_USB_LOWSPEED << 20;
+      break;
+    case GRUB_USB_SPEED_SUPER:
+      slot->ctx[0]    |= XHCI_USB_SUPERSPEED << 20;
+      break;
+    case GRUB_USB_SPEED_NONE:
+      slot->ctx[0]    |= 0 << 20;
+      break;
+  }
+
+  /* Route is greater zero on devices that are connected to a non root hub */
+  if (dev->route)
+    {
+      /* FIXME: Implement this code for non SuperSpeed hub devices */
+    }
+  slot->ctx[0]    |= dev->route;
+  slot->ctx[1]    |= (dev->root_port+1) << 16;
+
+  grub_arch_sync_dma_caches(in, size);
+
+  return dma;
+}
+
+/****************************************************************
+ * xHCI event processing
+ ****************************************************************/
+
+/* Dequeue events on the XHCI event ring generated by the hardware */
+static void xhci_process_events(struct grub_xhci *x)
+{
+    volatile struct grub_xhci_ring *evts = x->evts;
+    /* XXX invalidate caches */
+
+    for (;;) {
+	/* check for event */
+	grub_uint32_t nidx = grub_xhci_read32(&evts->nidx);
+	grub_uint32_t cs = grub_xhci_read32(&evts->cs);
+	volatile struct grub_xhci_trb *etrb = evts->ring + nidx;
+	grub_uint32_t control = grub_xhci_read32(&etrb->control);
+	if ((control & TRB_C) != (cs ? 1 : 0))
+	    return;
+
+	/* process event */
+	grub_uint32_t evt_type = TRB_TYPE(control);
+	grub_uint32_t evt_cc = (grub_xhci_read32(&etrb->status) >> 24) & 0xff;
+
+	switch (evt_type)
+	  {
+	    case ER_TRANSFER:
+	    case ER_COMMAND_COMPLETE:
+	      {
+		struct grub_xhci_trb  *rtrb = (void*)grub_xhci_read32(&etrb->ptr_low);
+		struct grub_xhci_ring *ring = XHCI_RING(rtrb);
+		volatile struct grub_xhci_trb  *evt = &ring->evt;
+		grub_uint32_t eidx = rtrb - ring->ring + 1;
+		grub_dprintf("xhci", "%s: ring %p [trb %p, evt %p, type %d, eidx %d, cc %d]\n",
+			      __func__, ring, rtrb, evt, evt_type, eidx, evt_cc);
+		*evt = *etrb;
+		grub_xhci_write32(&ring->eidx, eidx);
+		break;
+	      }
+	    case ER_PORT_STATUS_CHANGE:
+	      {
+		/* Nothing to do here. grub_xhci_detect_dev will handle it */
+		break;
+	      }
+	    default:
+	      {
+		grub_dprintf("xhci", "%s: unknown event, type %d, cc %d\n",
+			      __func__, evt_type, evt_cc);
+		break;
+	      }
+	}
+
+	/* move ring index, notify xhci */
+	nidx++;
+	if (nidx == GRUB_XHCI_RING_ITEMS)
+	  {
+	    nidx = 0;
+	    cs = cs ? 0 : 1;
+	    grub_xhci_write32(&evts->cs, cs);
+	  }
+	grub_xhci_write32(&evts->nidx, nidx);
+	volatile struct grub_xhci_ir *ir = x->ir;
+	grub_uint32_t erdp = (grub_uint32_t)(evts->ring + nidx);
+	grub_xhci_write32(&ir->erdp_low, erdp);
+	grub_xhci_write32(&ir->erdp_high, 0);
+    }
+}
+
+/****************************************************************
+ * TRB handling
+ ****************************************************************/
+
+/* Signal the hardware to process events on a TRB ring */
+static void xhci_doorbell(struct grub_xhci *x, grub_uint32_t slotid, grub_uint32_t value)
+{
+  xhci_check_status(x);
+  grub_dprintf("xhci", "%s: slotid %d, epid %d\n", __func__, slotid, value);
+  grub_xhci_write32(&x->db[slotid].doorbell, value);
+}
+
+/* Check if a ring has any pending TRBs */
+static int xhci_ring_busy(volatile struct grub_xhci_ring *ring)
+{
+  grub_uint32_t eidx = grub_xhci_read32(&ring->eidx);
+  grub_uint32_t nidx = grub_xhci_read32(&ring->nidx);
+
+  return (eidx != nidx);
+}
+
+/* Returns free space in ring */
+static int xhci_ring_free_space(volatile struct grub_xhci_ring *ring)
+{
+  grub_uint32_t eidx = grub_xhci_read32(&ring->eidx);
+  grub_uint32_t nidx = grub_xhci_read32(&ring->nidx);
+
+  /* nidx is never 0, so reduce ring buffer size by one */
+  return (eidx > nidx) ? eidx-nidx
+		: (ARRAY_SIZE(ring->ring) - 1) - nidx + eidx;
+}
+
+/* Check if a ring is full */
+static int xhci_ring_full(volatile struct grub_xhci_ring *ring)
+{
+  /* Might need to insert one link TRB */
+  return xhci_ring_free_space(ring) <= 1;
+}
+
+/* Check if a ring is almost full */
+static int xhci_ring_almost_full(volatile struct grub_xhci_ring *ring)
+{
+  /* Might need to insert one link TRB */
+  return xhci_ring_free_space(ring) <= 2;
+}
+
+/* Wait for a ring to empty (all TRBs processed by hardware) */
+static int xhci_event_wait(struct grub_xhci *x,
+			   volatile struct grub_xhci_ring *ring,
+			   grub_uint32_t timeout)
+{
+    grub_uint32_t end = grub_get_time_ms () + timeout;
+
+    for (;;)
+      {
+	xhci_check_status(x);
+	xhci_process_events(x);
+	if (!xhci_ring_busy(ring))
+	  {
+	    grub_uint32_t status = ring->evt.status;
+	    return (status >> 24) & 0xff;
+	  }
+	if (grub_get_time_ms () > end)
+	  {
+	    xhci_check_status(x);
+	    grub_dprintf("xhci", "%s: Timeout waiting for event\n", __func__);
+	    return -1;
+	  }
+      }
+}
+
+/* Add a TRB to the given ring, either regular or inline */
+static void xhci_trb_fill(volatile struct grub_xhci_ring *ring,
+			  grub_uint64_t ptr, grub_uint32_t xferlen,
+			  grub_uint32_t flags)
+{
+  volatile struct grub_xhci_trb *dst = &ring->ring[ring->nidx];
+  dst->ptr_low = ptr & 0xffffffff;
+  dst->ptr_high = ptr >> 32;
+  dst->status = xferlen;
+  dst->control = flags | (ring->cs ? TRB_C : 0);
+
+  grub_arch_sync_dma_caches(dst, sizeof(ring->ring[0]));
+}
+
+/*
+ * Queue a TRB onto a ring.
+ *
+ * The caller must pass a pointer to the data in physical address-space or the
+ * data itself (but no more than 8 bytes) in data_or_addr. Inline data must have
+ * the flag TRB_TR_IDT set.
+ */
+static void xhci_trb_queue(volatile struct grub_xhci_ring *ring,
+			   grub_uint64_t data_or_addr,
+			   grub_uint32_t xferlen, grub_uint32_t flags)
+{
+  grub_dprintf("xhci", "%s: ring %p data %llx len %d flags 0x%x remain 0x%x\n", __func__,
+      ring, data_or_addr, xferlen & 0x1ffff, flags, xferlen >> 17);
+
+  if (xhci_ring_full(ring))
+    {
+      grub_dprintf("xhci", "%s: ERROR: ring %p is full, discarding TRB\n",
+	__func__, ring);
+      return;
+    }
+
+  if (ring->nidx >= ARRAY_SIZE(ring->ring) - 1)
+    {
+      /* Reset to command buffer pointer to the first element */
+      xhci_trb_fill(ring, (grub_addr_t)ring->ring, 0, (TR_LINK << 10) | TRB_LK_TC);
+      ring->nidx = 0;
+      ring->cs ^= 1;
+      grub_dprintf("xhci", "%s: ring %p [linked]\n", __func__, ring);
+    }
+
+  xhci_trb_fill(ring, data_or_addr, xferlen, flags);
+  ring->nidx++;
+  grub_dprintf("xhci", "%s: ring %p [nidx %d, len %d]\n",
+	       __func__, ring, ring->nidx, xferlen);
+}
+
+/*
+ * Queue a TRB onto a ring and flush it if necessary.
+ *
+ * The caller must pass a pointer to the data in physical address-space or the
+ * data itself (but no more than 8 bytes) in data_or_addr. Inline data must have
+ * the flag TRB_TR_IDT set.
+ */
+static int xhci_trb_queue_and_flush(struct grub_xhci *x,
+				    grub_uint32_t slotid,
+				    grub_uint32_t epid,
+				    volatile struct grub_xhci_ring *ring,
+				    grub_uint64_t data_or_addr,
+				    grub_uint32_t xferlen, grub_uint32_t flags)
+{
+  grub_uint8_t submit = 0;
+  if (xhci_ring_almost_full(ring))
+    {
+      grub_dprintf("xhci", "%s: almost full e %d n %d\n", __func__, ring->eidx, ring->nidx);
+      flags |= TRB_TR_IOC;
+      submit = 1;
+    }
+  /* Note: xhci_trb_queue might queue on or two elements, if the end of the TRB
+   * has been reached. The caller must account for that when filling the TRB. */
+  xhci_trb_queue(ring, data_or_addr, xferlen, flags);
+  /* Submit if less no free slot is remaining, we might need an additional
+   * one on the next call to this function. */
+  if (submit)
+    {
+      xhci_doorbell(x, slotid, epid);
+      int rc = xhci_event_wait(x, ring, 1000);
+      grub_dprintf("xhci", "%s: xhci_event_wait = %d\n", __func__, rc);
+      return rc;
+    }
+  return 0;
+}
+
+/****************************************************************
+ * xHCI command functions
+ ****************************************************************/
+
+/* Submit a command to the xHCI command TRB */
+static int xhci_cmd_submit(struct grub_xhci *x,
+			   struct grub_pci_dma_chunk *inctx_dma,
+			   grub_uint32_t flags)
+{
+  volatile struct grub_xhci_inctx *inctx;
+  /* Don't submit if halted, it will fail */
+  if (xhci_is_halted(x))
+    return -1;
+
+  if (inctx_dma)
+    {
+      grub_xhci_inctx_sync_dma_caches(x, inctx_dma);
+
+      inctx = grub_dma_get_virt(inctx_dma);
+
+      struct grub_xhci_slotctx *slot = (void*)&inctx[1 << x->flag64];
+      grub_uint32_t port = ((slot->ctx[1] >> 16) & 0xff) - 1;
+      grub_uint32_t portsc = grub_xhci_port_read(x, port);
+      if (!(portsc & GRUB_XHCI_PORTSC_CCS))
+	{
+	  grub_dprintf("xhci", "%s: root port %d no longer connected\n",
+	    __func__, port);
+	  return -1;
+	}
+      xhci_trb_queue(x->cmds, grub_dma_get_phys(inctx_dma), 0, flags);
+    }
+    else
+    {
+      xhci_trb_queue(x->cmds, 0, 0, flags);
+    }
+
+    xhci_doorbell(x, 0, 0);
+    int rc = xhci_event_wait(x, x->cmds, 1000);
+    grub_dprintf("xhci", "%s: xhci_event_wait = %d\n", __func__, rc);
+
+    return rc;
+}
+
+static int xhci_cmd_enable_slot(struct grub_xhci *x)
+{
+  grub_uint32_t flags = 0;
+  flags |= (CR_ENABLE_SLOT << 10);
+
+  grub_dprintf("xhci", "%s:\n", __func__);
+  int cc = xhci_cmd_submit(x, NULL, flags);
+  if (cc != CC_SUCCESS)
+      return -1;
+  grub_dprintf("xhci", "%s: %p\n", __func__, &x->cmds->evt.control);
+  grub_dprintf("xhci", "%s: %x\n", __func__, grub_xhci_read32(&x->cmds->evt.control));
+
+  return (grub_xhci_read32(&x->cmds->evt.control) >> 24) & 0xff;
+}
+
+static int xhci_cmd_disable_slot(struct grub_xhci *x, grub_uint32_t slotid)
+{
+  grub_uint32_t flags = 0;
+  flags |= (CR_DISABLE_SLOT << 10);
+  flags |= (slotid << 24);
+
+  grub_dprintf("xhci", "%s: slotid %d\n", __func__, slotid);
+  return xhci_cmd_submit(x, NULL, flags);
+}
+
+static int xhci_cmd_stop_endpoint(struct grub_xhci *x, grub_uint32_t slotid
+				       , grub_uint32_t epid
+				       , grub_uint32_t suspend)
+{
+  grub_uint32_t flags = 0;
+  flags |= (CR_STOP_ENDPOINT << 10);
+  flags |= (epid << 16);
+  flags |= (suspend << 23) ;
+  flags |= (slotid << 24);
+
+  return xhci_cmd_submit(x, NULL, flags);
+}
+
+static int xhci_cmd_reset_endpoint(struct grub_xhci *x, grub_uint32_t slotid
+				       , grub_uint32_t epid
+				       , grub_uint32_t preserve)
+{
+  grub_uint32_t flags = 0;
+  flags |= (preserve << 9);
+  flags |= (CR_RESET_ENDPOINT << 10);
+  flags |= (epid << 16);
+  flags |= (slotid << 24);
+
+  return xhci_cmd_submit(x, NULL, flags);
+}
+
+static int xhci_cmd_set_dequeue_pointer(struct grub_xhci *x, grub_uint32_t slotid
+				       , grub_uint32_t epid
+				       , grub_addr_t tr_deque_pointer)
+{
+  grub_uint32_t flags = 0;
+  flags |= (CR_SET_TR_DEQUEUE << 10);
+  flags |= (epid << 16);
+  flags |= (slotid << 24);
+
+  xhci_trb_queue(x->cmds, tr_deque_pointer, 0, flags);
+
+  xhci_doorbell(x, 0, 0);
+  int rc = xhci_event_wait(x, x->cmds, 1000);
+  grub_dprintf("xhci", "%s: xhci_event_wait = %d\n", __func__, rc);
+
+  return rc;
+}
+
+static int xhci_cmd_address_device(struct grub_xhci *x, grub_uint32_t slotid,
+				   struct grub_pci_dma_chunk *inctx_dma)
+{
+  grub_uint32_t flags = 0;
+  flags |= (CR_ADDRESS_DEVICE << 10);
+  flags |= (slotid << 24);
+
+  grub_dprintf("xhci", "%s: slotid %d\n", __func__, slotid);
+  return xhci_cmd_submit(x, inctx_dma, flags);
+}
+
+static int xhci_cmd_configure_endpoint(struct grub_xhci *x, grub_uint32_t slotid,
+				       struct grub_pci_dma_chunk *inctx_dma)
+{
+  grub_uint32_t flags = 0;
+  flags |= (CR_CONFIGURE_ENDPOINT << 10);
+  flags |= (slotid << 24);
+
+  grub_dprintf("xhci", "%s: slotid %d\n", __func__, slotid);
+  return xhci_cmd_submit(x, inctx_dma, flags);
+}
+
+static int xhci_cmd_evaluate_context(struct grub_xhci *x, grub_uint32_t slotid,
+				     struct grub_pci_dma_chunk *inctx_dma)
+{
+  grub_uint32_t flags = 0;
+  flags |= (CR_EVALUATE_CONTEXT << 10);
+  flags |= (slotid << 24);
+
+  grub_dprintf("xhci", "%s: slotid %d\n", __func__, slotid);
+  return xhci_cmd_submit(x, inctx_dma, flags);
+}
+
+/****************************************************************
+ * xHCI host controller initialization
+ ****************************************************************/
+
+static grub_usb_err_t
+grub_xhci_reset (struct grub_xhci *x)
+{
+  grub_uint32_t reg;
+  grub_uint32_t end;
+
+  reg = grub_xhci_read32(&x->op->usbcmd);
+  if (reg & GRUB_XHCI_CMD_RS)
+    {
+      reg &= ~GRUB_XHCI_CMD_RS;
+      grub_xhci_write32(&x->op->usbcmd, reg);
+
+      end = grub_get_time_ms () + 32;
+      while (grub_xhci_read32(&x->op->usbcmd) & GRUB_XHCI_STS_HCH)
+	{
+	  if (grub_get_time_ms () > end)
+	      return GRUB_USB_ERR_TIMEOUT;
+
+	  grub_millisleep(1);
+	}
+    }
+
+  grub_dprintf("xhci", "grub_xhci_reset: resetting HC\n");
+  grub_xhci_write32(&x->op->usbcmd, GRUB_XHCI_CMD_HCRST);
+
+  /* Wait for device to complete reset and be enabled */
+  end = grub_get_time_ms () + 100;
+  while (grub_xhci_read32(&x->op->usbcmd) & GRUB_XHCI_CMD_HCRST)
+    {
+      if (grub_get_time_ms () > end)
+	  return GRUB_USB_ERR_TIMEOUT;
+
+      grub_millisleep(1);
+    }
+
+  /* Wait for device to complete reset and be enabled */
+  end = grub_get_time_ms () + 100;
+  while (grub_xhci_read32(&x->op->usbsts) & GRUB_XHCI_STS_CNR)
+    {
+      if (grub_get_time_ms () > end)
+	  return GRUB_USB_ERR_TIMEOUT;
+
+      grub_millisleep(1);
+    }
+
+  grub_xhci_write32(&x->op->config, x->slots);
+  grub_xhci_write32(&x->op->dcbaap_low, grub_dma_get_phys(x->devs_dma));
+  grub_xhci_write32(&x->op->dcbaap_high, 0);
+  grub_xhci_write32(&x->op->crcr_low, grub_dma_get_phys(x->cmds_dma)| 1);
+  grub_xhci_write32(&x->op->crcr_high, 0);
+  x->cmds->cs = 1;
+
+  grub_arch_sync_dma_caches(x->cmds, sizeof(*x->cmds));
+
+  x->eseg->ptr_low = grub_dma_get_phys(x->evts_dma);
+  x->eseg->ptr_high = 0;
+  x->eseg->size = GRUB_XHCI_RING_ITEMS;
+
+  grub_arch_sync_dma_caches(x->eseg, sizeof(*x->eseg));
+
+  grub_xhci_write32(&x->ir->erstsz, 1);
+  grub_xhci_write32(&x->ir->erdp_low, grub_dma_get_phys(x->evts_dma));
+  grub_xhci_write32(&x->ir->erdp_high, 0);
+  grub_xhci_write32(&x->ir->erstba_low, grub_dma_get_phys(x->eseg_dma));
+  grub_xhci_write32(&x->ir->erstba_high, 0);
+  x->evts->cs = 1;
+
+  grub_arch_sync_dma_caches(x->evts, sizeof(*x->eseg));
+
+  xhci_check_status(x);
+
+  grub_dprintf ("xhci", "XHCI OP COMMAND: %08x\n",
+		grub_xhci_read32 (&x->op->usbcmd));
+  grub_dprintf ("xhci", "XHCI OP STATUS: %08x\n",
+		grub_xhci_read32 (&x->op->usbsts));
+  grub_dprintf ("xhci", "XHCI OP PAGESIZE: %08x\n",
+		grub_xhci_read32 (&x->op->pagesize));
+  grub_dprintf ("xhci", "XHCI OP DNCTRL: %08x\n",
+		grub_xhci_read32 (&x->op->dnctl));
+  grub_dprintf ("xhci", "XHCI OP CRCR_LOW: %08x\n",
+		grub_xhci_read32 (&x->op->crcr_low));
+  grub_dprintf ("xhci", "XHCI OP CRCR_HIGH: %08x\n",
+		grub_xhci_read32 (&x->op->crcr_high));
+  grub_dprintf ("xhci", "XHCI OP DCBAAP_LOW: %08x\n",
+		grub_xhci_read32 (&x->op->dcbaap_low));
+  grub_dprintf ("xhci", "XHCI OP DCBAAP_HIGH: %08x\n",
+		grub_xhci_read32 (&x->op->dcbaap_high));
+  grub_dprintf ("xhci", "XHCI OP CONFIG: %08x\n",
+		grub_xhci_read32 (&x->op->config));
+  grub_dprintf ("xhci", "XHCI IR ERSTSZ: %08x\n",
+		grub_xhci_read32 (&x->ir->erstsz));
+  grub_dprintf ("xhci", "XHCI IR ERDP: %08x\n",
+		grub_xhci_read32 (&x->ir->erdp_low));
+  grub_dprintf ("xhci", "XHCI IR ERSTBA: %08x\n",
+		grub_xhci_read32 (&x->ir->erstba_low));
+
+  xhci_check_status(x);
+
+  return GRUB_USB_ERR_NONE;
+}
+
+static grub_usb_err_t
+grub_xhci_request_legacy_handoff(volatile struct grub_xhci_xcap *xcap)
+{
+  grub_uint32_t end;
+
+  end = grub_get_time_ms () + 10;
+  for (;;)
+    {
+      grub_uint32_t cap = grub_xhci_read32(&xcap->cap);
+      if (cap & (1 << 16))
+	grub_xhci_write32(&xcap->cap, cap | (1 << 24));
+      else
+        break;
+
+      if (grub_get_time_ms () > end)
+	{
+	  grub_dprintf ("xhci","ERROR: %s TIMEOUT\n", __func__);
+	  return GRUB_USB_ERR_TIMEOUT;
+	}
+      grub_millisleep(1);
+    }
+  return GRUB_USB_ERR_NONE;
+}
+
+static void
+grub_xhci_fill_default_speed_mapping(struct grub_xhci_psids *ids)
+{
+	/* Chapter 7.2.2.1.1 "Default USB Speed ID Mapping" */
+	ids->psids[0].id = 1;
+	ids->psids[0].psie = 2;
+	ids->psids[0].psim = 12;
+	ids->psids[1].id = 2;
+	ids->psids[1].psie = 1;
+	ids->psids[1].psim = 1500;
+	ids->psids[2].id = 3;
+	ids->psids[2].psie = 2;
+	ids->psids[2].psim = 480;
+	ids->psids[3].id = 4;
+	ids->psids[3].psie = 3;
+	ids->psids[3].psim = 5;
+	ids->psids[4].id = 5;
+	ids->psids[4].psie = 3;
+	ids->psids[4].psim = 10;
+	ids->psids[5].id = 6;
+	ids->psids[5].psie = 3;
+	ids->psids[5].psim = 10;
+	ids->psids[6].id = 7;
+	ids->psids[6].psie = 3;
+	ids->psids[6].psim = 20;
+}
+
+static void
+grub_xhci_calc_speed_mapping(struct grub_xhci_psids *ids)
+{
+  const grub_uint64_t mult[4] = {1ULL, 1000ULL, 1000000ULL, 1000000000ULL};
+
+  for (grub_uint8_t i = 0; i < 16; i++)
+    {
+      if (ids->psids[i].id == 0)
+	continue;
+      ids->psids[i].bitrate = mult[ids->psids[i].psie & 3] * (grub_uint64_t)ids->psids[i].psim;
+      if (ids->psids[i].bitrate < 12000000ULL)
+	ids->psids[i].grub_usb_speed = GRUB_USB_SPEED_LOW;
+      else if (ids->psids[i].bitrate < 480000000ULL)
+	ids->psids[i].grub_usb_speed = GRUB_USB_SPEED_FULL;
+      else if (ids->psids[i].bitrate > 1200000000ULL)
+	ids->psids[i].grub_usb_speed = GRUB_USB_SPEED_SUPER;
+      else
+	ids->psids[i].grub_usb_speed = GRUB_USB_SPEED_HIGH;
+    }
+}
+
+
+/* PCI iteration function... */
+void
+grub_xhci_init_device (volatile void *regs)
+{
+  struct grub_xhci *x;
+  grub_uint32_t hcs1, hcc, reg;
+
+  /* Allocate memory for the controller and fill basic values. */
+  x = grub_zalloc (sizeof (*x));
+  if (!x)
+    {
+      grub_dprintf("xhci", "Failed to allocate memory\n");
+      return;
+    }
+  x->caps = (volatile struct grub_xhci_caps *) regs;
+  x->op = (volatile struct grub_xhci_op *) (((grub_uint8_t *)regs) +
+      grub_xhci_read8(&x->caps->caplength));
+  x->pr = (volatile struct grub_xhci_pr *) (((grub_uint8_t *)x->op) +
+      GRUB_XHCI_PR_OFFSET);
+  x->db = (volatile struct grub_xhci_db *) (((grub_uint8_t *)regs) +
+      grub_xhci_read32(&x->caps->dboff));
+  x->ir = (volatile struct grub_xhci_ir *) (((grub_uint8_t *)regs) +
+		  grub_xhci_read32(&x->caps->rtsoff) + GRUB_XHCI_IR_OFFSET);
+
+  grub_dprintf ("xhci", "XHCI init: CAPLENGTH: 0x%02x\n",
+		grub_xhci_read8 (&x->caps->caplength));
+  grub_dprintf ("xhci", "XHCI init: HCIVERSION: 0x%04x\n",
+		grub_xhci_read16 (&x->caps->hciversion));
+  grub_dprintf ("xhci", "XHCI init: HCSPARAMS1: 0x%08x\n",
+		grub_xhci_read32 (&x->caps->hcsparams1));
+  grub_dprintf ("xhci", "XHCI init: HCSPARAMS2: 0x%08x\n",
+		grub_xhci_read32 (&x->caps->hcsparams2));
+  grub_dprintf ("xhci", "XHCI init: HCSPARAMS3: 0x%08x\n",
+		grub_xhci_read32 (&x->caps->hcsparams3));
+  grub_dprintf ("xhci", "XHCI init: HCCPARAMS: 0x%08x\n",
+		grub_xhci_read32 (&x->caps->hcsparams3));
+  grub_dprintf ("xhci", "XHCI init: DBOFF: 0x%08x\n",
+		grub_xhci_read32 (&x->caps->dboff));
+  grub_dprintf ("xhci", "XHCI init: RTOFF: 0x%08x\n",
+		grub_xhci_read32 (&x->caps->rtsoff));
+
+  hcs1 = grub_xhci_read32(&x->caps->hcsparams1);
+  hcc = grub_xhci_read32(&x->caps->hccparams);
+  x->ports = (grub_uint32_t) ((hcs1 >> 24) & 0xff);
+  x->slots = (grub_uint32_t) (hcs1	 & 0xff);
+  x->xcap  = (grub_uint32_t) ((hcc >> 16) & 0xffff) * sizeof(grub_uint32_t);
+  x->flag64 = (grub_uint8_t) ((hcc & 0x04) ? 1 : 0);
+  grub_dprintf("xhci", "XHCI init: %d ports, %d slots, %d byte contexts\n"
+	       , x->ports, x->slots, x->flag64 ? 64 : 32);
+
+  x->psids = grub_zalloc (sizeof (struct grub_xhci_psids) * x->ports);
+  if (x->xcap)
+    {
+      grub_uint32_t off;
+      volatile grub_uint8_t *addr = (grub_uint8_t *) x->caps + x->xcap;
+      do
+	{
+	  volatile struct grub_xhci_xcap *xcap = (void *)addr;
+	  grub_uint32_t ports, name, cap = grub_xhci_read32(&xcap->cap);
+	  switch (cap & 0xff) {
+	    case XHCI_CAP_LEGACY_SUPPORT:
+	      {
+		if (grub_xhci_request_legacy_handoff(xcap) != GRUB_USB_ERR_NONE)
+		  {
+		    grub_dprintf("xhci", "XHCI init: Failed to get xHCI ownership\n");
+		    goto fail;
+		  }
+	        break;
+	      }
+	    case XHCI_CAP_SUPPORTED_PROTOCOL:
+	      {
+		name  = grub_xhci_read32(&xcap->data[0]);
+		ports = grub_xhci_read32(&xcap->data[1]);
+		const grub_uint8_t major = (cap >> 24) & 0xff;
+		const grub_uint8_t minor = (cap >> 16) & 0xff;
+		const grub_uint8_t psic = (ports >> 28) & 0xf;
+		const grub_uint8_t count = (ports >> 8) & 0xff;
+		const grub_uint8_t start = (ports >> 0) & 0xff;
+		grub_dprintf("xhci", "XHCI init: protocol %c%c%c%c %x.%02x"
+				", %d ports (offset %d), def %x, psic %d\n"
+				, (name >>  0) & 0xff
+				, (name >>  8) & 0xff
+				, (name >> 16) & 0xff
+				, (name >> 24) & 0xff
+				, major, minor
+				, count, start
+				, ports >> 16
+				, psic);
+		if (name == 0x20425355 /* "USB " */)
+		  {
+		    if (major == 2)
+		      {
+			x->usb2.start = start;
+			x->usb2.count = count;
+		      }
+		    else if (major == 3)
+		      {
+			x->usb3.start = start;
+			x->usb3.count = count;
+		      }
+
+		    for (grub_uint32_t p = start - 1; p < start + count - 1UL; p++)
+		      {
+			x->psids[p].major = major;
+			x->psids[p].minor = minor;
+			grub_xhci_fill_default_speed_mapping(&x->psids[p]);
+			for (grub_uint8_t i = 0; i < psic; i++)
+			  {
+			    grub_uint32_t psid = grub_xhci_read32(&xcap->data[3 + i]);
+			    x->psids[p].psids[i].id = (psid >> 0) & 0xf;
+			    x->psids[p].psids[i].psie = (psid >> 4) & 0x3;
+			    x->psids[p].psids[i].psim = (psid >> 16) & 0xfffff;
+			  }
+			grub_xhci_calc_speed_mapping(&x->psids[p]);
+		      }
+		  }
+
+		break;
+	      }
+	    default:
+	      {
+	        grub_dprintf("xhci", "XHCI    extcap 0x%x @ %p\n", cap & 0xff, addr);
+	        break;
+	      }
+	  }
+	off = (cap >> 8) & 0xff;
+	addr += off << 2;
+	}
+      while (off > 0);
+    }
+
+  x->pagesize = xhci_get_pagesize(x);
+  grub_dprintf("xhci", "XHCI init: Minimum supported page size 0x%x\n",
+	       x->pagesize);
+
+  /* Chapter 6.1 Device Context Base Address Array */
+  x->devs_dma = xhci_memalign_dma32(ALIGN_DCBAA,
+				    sizeof(*x->devs) * (x->slots + 1),
+				    x->pagesize);
+  if (!x->devs_dma)
+      goto fail;
+  x->devs = grub_dma_get_virt(x->devs_dma);
+  grub_memset((void *)x->devs, 0, sizeof(*x->devs) * (x->slots + 1));
+  grub_arch_sync_dma_caches(x->devs, sizeof(*x->devs) * (x->slots + 1));
+  grub_dprintf ("xhci", "XHCI init: device memory %p (%x)\n",
+		grub_dma_get_virt(x->devs_dma),
+		grub_dma_get_phys(x->devs_dma));
+
+  /* Chapter 6.5 Event Ring Segment Table */
+  x->eseg_dma = xhci_memalign_dma32(ALIGN_EVT_RING_TABLE, sizeof(*x->eseg), 0);
+  if (!x->eseg_dma)
+      goto fail;
+  x->eseg = grub_dma_get_virt(x->eseg_dma);
+  grub_memset((void *)x->eseg, 0, sizeof(*x->eseg));
+  grub_arch_sync_dma_caches(x->eseg, sizeof(*x->eseg));
+  grub_dprintf ("xhci", "XHCI init: event ring table memory %p (%x)\n",
+		grub_dma_get_virt(x->eseg_dma),
+		grub_dma_get_phys(x->eseg_dma));
+
+  x->cmds_dma = xhci_memalign_dma32(ALIGN_CMD_RING_SEG, sizeof(*x->cmds),
+				    BOUNDARY_RING);
+  if (!x->cmds_dma)
+      goto fail;
+  x->cmds = grub_dma_get_virt(x->cmds_dma);
+  grub_memset((void *)x->cmds, 0, sizeof(*x->cmds));
+  grub_arch_sync_dma_caches(x->cmds, sizeof(*x->cmds));
+  grub_dprintf ("xhci", "XHCI init: command ring memory %p (%x)\n",
+		grub_dma_get_virt(x->cmds_dma),
+		grub_dma_get_phys(x->cmds_dma));
+
+  x->evts_dma = xhci_memalign_dma32(ALIGN_EVT_RING_SEG, sizeof(*x->evts),
+				    BOUNDARY_RING);
+  if (!x->evts_dma)
+      goto fail;
+  x->evts = grub_dma_get_virt(x->evts_dma);
+  grub_memset((void *)x->evts, 0, sizeof(*x->evts));
+  grub_arch_sync_dma_caches(x->evts, sizeof(*x->evts));
+  grub_dprintf ("xhci", "XHCI init: event ring memory %p (%x)\n",
+		grub_dma_get_virt(x->evts_dma),
+		grub_dma_get_phys(x->evts_dma));
+
+  /* Chapter 4.20 Scratchpad Buffers */
+  reg = grub_xhci_read32(&x->caps->hcsparams2);
+  x->spb = (reg >> 21 & 0x1f) << 5 | reg >> 27;
+  if (x->spb)
+    {
+      volatile grub_uint64_t *spba;
+      grub_dprintf("xhci", "XHCI init: set up %d scratch pad buffers\n",
+		   x->spb);
+      x->spba_dma = xhci_memalign_dma32(ALIGN_SPBA, sizeof(*spba) * x->spb,
+					x->pagesize);
+      if (!x->spba_dma)
+	goto fail;
+
+      x->spad_dma = xhci_memalign_dma32(x->pagesize, x->pagesize * x->spb,
+					x->pagesize);
+      if (!x->spad_dma)
+	{
+	  grub_dma_free(x->spba_dma);
+	  goto fail;
+	}
+
+      spba = grub_dma_get_virt(x->spba_dma);
+      for (grub_uint32_t i = 0; i < x->spb; i++)
+	spba[i] = (grub_addr_t)grub_dma_get_phys(x->spad_dma) + (i * x->pagesize);
+      grub_arch_sync_dma_caches(x->spba_dma, sizeof(*spba) * x->spb);
+
+      x->devs[0].ptr_low = grub_dma_get_phys(x->spba_dma);
+      x->devs[0].ptr_high = 0;
+      grub_arch_sync_dma_caches(x->devs_dma, sizeof(x->devs[0]));
+      grub_dprintf ("xhci", "XHCI init: Allocated %d scratch buffers of size 0x%x\n",
+		    x->spb, x->pagesize);
+    }
+
+  grub_xhci_reset(x);
+
+  /* Set the running bit */
+  reg = grub_xhci_read32 (&x->op->usbcmd);
+  reg |= GRUB_XHCI_CMD_RS;
+  grub_xhci_write32 (&x->op->usbcmd, reg);
+
+
+  /* Link to xhci now that initialisation is successful.  */
+  x->next = xhci;
+  xhci = x;
+
+  return;
+
+fail:
+  grub_dprintf ("xhci", "XHCI grub_xhci_pci_iter: FAILED!\n");
+  if (x)
+    {
+      if (x->devs_dma)
+	grub_dma_free (x->devs_dma);
+      if (x->eseg_dma)
+	grub_dma_free (x->eseg_dma);
+      if (x->cmds_dma)
+	grub_dma_free (x->cmds_dma);
+      if (x->evts_dma)
+	grub_dma_free (x->evts_dma);
+      if (x->spad_dma)
+	grub_dma_free (x->spad_dma);
+      if (x->spba_dma)
+	grub_dma_free (x->spba_dma);
+    }
+  grub_free (x);
+
+  return;
+}
+
+static int
+grub_xhci_iterate (grub_usb_controller_iterate_hook_t hook, void *hook_data)
+{
+  struct grub_xhci *x;
+  struct grub_usb_controller dev;
+
+  for (x = xhci; x; x = x->next)
+    {
+      dev.data = x;
+      if (hook (&dev, hook_data))
+	return 1;
+    }
+
+  return 0;
+}
+
+/****************************************************************
+ * xHCI maintainance functions 
+ ****************************************************************/
+
+static grub_usb_err_t
+grub_xhci_update_hub_portcount (struct grub_xhci *x,
+				grub_usb_transfer_t transfer,
+				grub_uint32_t slotid)
+{
+  struct grub_pci_dma_chunk *in_dma;
+  volatile struct grub_xhci_slotctx *hdslot;
+  grub_uint32_t epid = 0;
+
+  if (!transfer || !transfer->dev || !transfer->dev->nports)
+    return GRUB_USB_ERR_NONE;
+
+  hdslot = grub_dma_phys2virt(x->devs[slotid].ptr_low, x->devs_dma);
+  if ((hdslot->ctx[3] >> 27) == 3)
+    /* Already configured */
+    return 0;
+
+  grub_dprintf("xhci", "%s: updating hub config to %d ports\n", __func__,
+	       transfer->dev->nports);
+
+  xhci_check_status(x);
+
+  /* Allocate input context and initialize endpoint info. */
+  in_dma = grub_xhci_alloc_inctx(x, epid, transfer->dev);
+  if (!in_dma)
+    return GRUB_USB_ERR_INTERNAL;
+  volatile struct grub_xhci_inctx *in = grub_dma_get_virt(in_dma);
+
+  in->add = (1 << epid);
+
+  struct grub_xhci_epctx *ep = (void*)&in[(epid+1) << x->flag64];
+  ep->ctx[0]   |= 1 << 26;
+  ep->ctx[1]   |= transfer->dev->nports << 24;
+
+  int cc = xhci_cmd_configure_endpoint(x, slotid, in_dma);
+  grub_dma_free(in_dma);
+
+  if (cc != CC_SUCCESS)
+    {
+      grub_dprintf("xhci", "%s: reconf ctl endpoint: failed (cc %d)\n",
+		   __func__, cc);
+      return GRUB_USB_ERR_BADDEVICE;
+    }
+
+  return GRUB_USB_ERR_NONE;
+}
+
+static grub_usb_err_t
+grub_xhci_update_max_paket_size (struct grub_xhci *x,
+				 grub_usb_transfer_t transfer,
+				 grub_uint32_t slotid,
+				 grub_uint32_t max_packet)
+{
+  struct grub_pci_dma_chunk *in_dma;
+  grub_uint32_t epid = 1;
+
+  if (!transfer || !transfer->dev || !max_packet)
+    return GRUB_USB_ERR_NONE;
+
+  grub_dprintf("xhci", "%s: updating max packet size to 0x%x\n", __func__,
+	       max_packet);
+
+  xhci_check_status(x);
+
+  /* Allocate input context and initialize endpoint info. */
+  in_dma = grub_xhci_alloc_inctx(x, epid, transfer->dev);
+  if (!in_dma)
+    return GRUB_USB_ERR_INTERNAL;
+  volatile struct grub_xhci_inctx *in = grub_dma_get_virt(in_dma);
+  in->add = (1 << epid);
+
+  struct grub_xhci_epctx *ep = (void*)&in[(epid+1) << x->flag64];
+  ep->ctx[1]   |= max_packet << 16;
+
+  int cc = xhci_cmd_evaluate_context(x, slotid, in_dma);
+  grub_dma_free(in_dma);
+
+  if (cc != CC_SUCCESS)
+    {
+      grub_dprintf("xhci", "%s: reconf ctl endpoint: failed (cc %d)\n",
+		   __func__, cc);
+      return GRUB_USB_ERR_BADDEVICE;
+    }
+
+  return GRUB_USB_ERR_NONE;
+}
+
+/****************************************************************
+ * xHCI endpoint enablement functions
+ ****************************************************************/
+
+static grub_usb_err_t
+grub_xhci_prepare_endpoint (struct grub_xhci *x,
+			    struct grub_usb_device *dev,
+			    grub_uint8_t endpoint,
+			    grub_transfer_type_t dir,
+			    grub_transaction_type_t type,
+			    grub_uint32_t maxpaket,
+			    struct grub_xhci_priv *priv)
+{
+  grub_uint32_t epid;
+  struct grub_pci_dma_chunk *reqs_dma;
+  struct grub_pci_dma_chunk *in_dma;
+  volatile struct grub_xhci_ring *reqs;
+  volatile struct grub_xhci_slotctx *slotctx;
+
+  if (!x || !priv)
+    return GRUB_USB_ERR_INTERNAL;
+
+  xhci_check_status(x);
+
+  if (endpoint == 0)
+    {
+      epid = 1;
+    }
+  else
+    {
+      epid = (endpoint & 0x0f) * 2;
+      epid += (dir == GRUB_USB_TRANSFER_TYPE_IN) ? 1 : 0;
+    }
+  grub_dprintf("xhci", "%s: epid %d\n", __func__, epid);
+
+  /* Test if already prepared */
+  if (priv->slotid > 0 && priv->enpoint_trbs[epid] != NULL)
+    return GRUB_USB_ERR_NONE;
+
+  /* Allocate DMA buffer as endpoint cmd TRB */
+  reqs_dma = xhci_memalign_dma32(ALIGN_TRB, sizeof(*reqs),
+				 BOUNDARY_RING);
+  if (!reqs_dma)
+    return GRUB_USB_ERR_INTERNAL;
+  reqs = grub_dma_get_virt(reqs_dma);
+  grub_memset((void *)reqs, 0, sizeof(*reqs));
+  reqs->cs = 1;
+
+  grub_arch_sync_dma_caches(reqs, sizeof(*reqs));
+
+  /* Allocate input context and initialize endpoint info. */
+  in_dma = grub_xhci_alloc_inctx(x, epid, dev);
+  if (!in_dma)
+    {
+      grub_dma_free(reqs_dma);
+      return GRUB_USB_ERR_INTERNAL;
+    }
+  volatile struct grub_xhci_inctx *in = grub_dma_get_virt(in_dma);
+  in->add = 0x01 | (1 << epid);
+
+  struct grub_xhci_epctx *ep = (void*)&in[(epid+1) << x->flag64];
+  switch (type)
+    {
+      case GRUB_USB_TRANSACTION_TYPE_CONTROL:
+        ep->ctx[1]   |= 0 << 3;
+        break;
+      case GRUB_USB_TRANSACTION_TYPE_BULK:
+        ep->ctx[1]   |= 2 << 3;
+        break;
+    }
+  if (dir == GRUB_USB_TRANSFER_TYPE_IN
+      || type== GRUB_USB_TRANSACTION_TYPE_CONTROL)
+      ep->ctx[1] |= 1 << 5;
+  ep->ctx[1]   |= maxpaket << 16;
+  ep->deq_low  = grub_dma_get_phys(reqs_dma);
+  ep->deq_low  |= 1;	 /* dcs */
+  ep->length   = maxpaket;
+
+  grub_dprintf("xhci", "%s: ring %p, epid %d, max %d\n", __func__,
+	       reqs, epid, maxpaket);
+  if (epid == 1 || priv->slotid == 0) {
+    /* Enable slot. */
+    int slotid = xhci_cmd_enable_slot(x);
+    if (slotid < 0)
+      {
+	grub_dprintf("xhci", "%s: enable slot: failed\n", __func__);
+	grub_dma_free(reqs_dma);
+	grub_dma_free(in_dma);
+	return GRUB_USB_ERR_BADDEVICE;
+      }
+    grub_dprintf("xhci", "%s: get slot %d assigned\n", __func__, slotid);
+
+    grub_uint32_t size = (sizeof(struct grub_xhci_slotctx) * GRUB_XHCI_MAX_ENDPOINTS) << x->flag64;
+
+    /* Allocate memory for the device specific slot context */
+    priv->slotctx_dma = xhci_memalign_dma32(ALIGN_SLOTCTX, size,
+					    x->pagesize);
+    if (!priv->slotctx_dma)
+      {
+	grub_dprintf("xhci", "%s: grub_memalign_dma32 failed\n", __func__);
+	grub_dma_free(reqs_dma);
+	grub_dma_free(in_dma);
+	return GRUB_USB_ERR_INTERNAL;
+      }
+    slotctx = grub_dma_get_virt(priv->slotctx_dma);
+
+    grub_dprintf("xhci", "%s: enable slot: got slotid %d\n", __func__, slotid);
+    grub_memset((void *)slotctx, 0, size);
+    grub_arch_sync_dma_caches(slotctx, size);
+
+    x->devs[slotid].ptr_low = grub_dma_get_phys(priv->slotctx_dma);
+    x->devs[slotid].ptr_high = 0;
+    grub_arch_sync_dma_caches(&x->devs[slotid], sizeof(x->devs[0]));
+
+    /* Send set_address command. */
+    int cc = xhci_cmd_address_device(x, slotid, in_dma);
+    if (cc != CC_SUCCESS)
+      {
+	grub_dprintf("xhci","%s: address device: failed (cc %d)\n", __func__, cc);
+	cc = xhci_cmd_disable_slot(x, slotid);
+	if (cc != CC_SUCCESS) {
+	    grub_dprintf("xhci", "%s: disable failed (cc %d)\n", __func__, cc);
+	} else {
+	  x->devs[slotid].ptr_low = 0;
+	  x->devs[slotid].ptr_high = 0;
+	  grub_arch_sync_dma_caches(&x->devs[slotid], sizeof(x->devs[0]));
+	}
+	grub_dma_free(priv->slotctx_dma);
+	grub_dma_free(reqs_dma);
+	grub_dma_free(in_dma);
+	return GRUB_USB_ERR_BADDEVICE;
+      }
+    priv->enpoint_trbs[epid] = reqs;
+    priv->enpoint_trbs_dma[epid] = reqs_dma;
+    priv->slotid = slotid;
+    priv->max_packet = 0;
+  }
+  if (epid != 1)
+    {
+	/* Send configure command. */
+	int cc = xhci_cmd_configure_endpoint(x, priv->slotid, in_dma);
+	if (cc != CC_SUCCESS)
+	  {
+	    grub_dprintf("xhci", "%s: configure endpoint: failed (cc %d)\n",
+			 __func__, cc);
+	    grub_dma_free(reqs_dma);
+	    grub_dma_free(in_dma);
+	    return GRUB_USB_ERR_BADDEVICE;
+	  }
+      priv->enpoint_trbs[epid] = reqs;
+      priv->enpoint_trbs_dma[epid] = reqs_dma;
+    }
+
+  grub_dprintf("xhci", "%s: done\n", __func__);
+  grub_dma_free(in_dma);
+
+  return GRUB_USB_ERR_NONE;
+}
+
+
+/****************************************************************
+ * xHCI transfer helper functions
+ ****************************************************************/
+
+static grub_usb_err_t
+grub_xhci_usb_to_grub_err (unsigned char status)
+{
+  if (status != CC_SUCCESS)
+    grub_dprintf("xhci", "%s: xfer failed (cc %d)\n", __func__, status);
+  else
+    grub_dprintf("xhci", "%s: xfer done   (cc %d)\n", __func__, status);
+
+  if (status == CC_BABBLE_DETECTED)
+    return GRUB_USB_ERR_BABBLE;
+  else if (status == CC_DATA_BUFFER_ERROR)
+    return GRUB_USB_ERR_DATA;
+  else if (status == CC_STALL_ERROR)
+    return GRUB_USB_ERR_STALL;
+  else if (status != CC_SUCCESS)
+    return GRUB_USB_ERR_NAK;
+
+  return GRUB_USB_ERR_NONE;
+}
+
+static int
+grub_xhci_transfer_is_zlp(grub_usb_transfer_t transfer, int idx)
+{
+  if (idx >= transfer->transcnt)
+    return 0;
+
+  grub_usb_transaction_t tr = &transfer->transactions[idx];
+
+  return (tr->size == 0) &&
+    ((tr->pid == GRUB_USB_TRANSFER_TYPE_OUT) ||
+    (tr->pid == GRUB_USB_TRANSFER_TYPE_IN));
+}
+
+static int
+grub_xhci_transfer_is_last(grub_usb_transfer_t transfer, int idx)
+{
+    return (idx + 1) == transfer->transcnt;
+}
+
+static int
+grub_xhci_transfer_is_data(grub_usb_transfer_t transfer, int idx)
+{
+  grub_usb_transaction_t tr;
+
+  if (idx >= transfer->transcnt)
+    return 0;
+
+  tr = &transfer->transactions[idx];
+  if (tr->size == 0 ||
+      (tr->pid == GRUB_USB_TRANSFER_TYPE_SETUP))
+    return 0;
+
+  /* If there's are no DATA pakets before it's a DATA paket */
+  for (int i = idx - 1; i >= 0; i--)
+    {
+      tr = &transfer->transactions[i];
+      if (tr->size > 0 &&
+	  ((tr->pid == GRUB_USB_TRANSFER_TYPE_OUT) ||
+	  (tr->pid == GRUB_USB_TRANSFER_TYPE_IN)))
+	    return 0;
+    }
+  return 1;
+}
+
+static int
+grub_xhci_transfer_is_in(grub_usb_transfer_t transfer, int idx)
+{
+  grub_usb_transaction_t tr;
+
+  if (idx >= transfer->transcnt)
+    return 0;
+
+  tr = &transfer->transactions[idx];
+
+  return tr->pid == GRUB_USB_TRANSFER_TYPE_IN;
+}
+
+static int
+grub_xhci_transfer_is_normal(grub_usb_transfer_t transfer, int idx)
+{
+  grub_usb_transaction_t tr;
+
+  if (idx >= transfer->transcnt)
+    return 0;
+
+  tr = &transfer->transactions[idx];
+  if (tr->size == 0 ||
+      (tr->pid == GRUB_USB_TRANSFER_TYPE_SETUP))
+    return 0;
+
+  /* If there's at least one DATA paket before it's a normal */
+  for (int i = idx - 1; i >= 0; i--)
+    {
+      tr = &transfer->transactions[i];
+      if (tr->size > 0 &&
+	  ((tr->pid == GRUB_USB_TRANSFER_TYPE_OUT) ||
+	  (tr->pid == GRUB_USB_TRANSFER_TYPE_IN)))
+	    return 1;
+
+    }
+  return 0;
+}
+
+static int
+grub_xhci_transfer_next_is_normal(grub_usb_transfer_t transfer, int idx)
+{
+  return grub_xhci_transfer_is_normal(transfer, idx + 1);
+}
+
+static int
+grub_xhci_transfer_next_is_in(grub_usb_transfer_t transfer, int idx)
+{
+  return grub_xhci_transfer_is_in(transfer, idx + 1);
+}
+
+static grub_uint8_t grub_xhci_epid_from_transfer(grub_usb_transfer_t transfer)
+{
+  grub_uint8_t epid;
+
+  if (transfer->endpoint == 0) {
+      epid = 1;
+  } else {
+    epid = (transfer->endpoint & 0x0f) * 2;
+    epid += (transfer->dir == GRUB_USB_TRANSFER_TYPE_IN) ? 1 : 0;
+  }
+  return epid;
+}
+
+/****************************************************************
+ * xHCI transfer functions
+ ****************************************************************/
+
+static grub_usb_err_t
+grub_xhci_setup_transfer (grub_usb_controller_t dev,
+			  grub_usb_transfer_t transfer)
+{
+  struct grub_xhci_transfer_controller_data *cdata;
+  struct grub_xhci *x = (struct grub_xhci *) dev->data;
+  grub_uint8_t epid;
+  grub_usb_err_t err;
+  volatile struct grub_xhci_ring *reqs;
+  int rc;
+  struct grub_xhci_priv *priv;
+
+   xhci_check_status(x);
+
+  if (!dev || !transfer || !transfer->dev || !transfer->dev->xhci_priv)
+    return GRUB_USB_ERR_INTERNAL;
+
+  priv = transfer->dev->xhci_priv;
+  err = grub_xhci_prepare_endpoint(x, transfer->dev,
+				   transfer->endpoint,
+				   transfer->dir,
+				   transfer->type,
+				   transfer->max,
+				   priv);
+
+  if (err != GRUB_USB_ERR_NONE)
+    return err;
+
+  epid = grub_xhci_epid_from_transfer(transfer);
+
+  /* Update the max packet size once descdev.maxsize0 is valid */
+  if (epid == 1 &&
+      (priv->max_packet == 0) &&
+      (transfer->dev->descdev.maxsize0 > 0))
+    {
+      if (transfer->dev->speed == GRUB_USB_SPEED_SUPER)
+        priv->max_packet = 1UL << transfer->dev->descdev.maxsize0;
+      else
+        priv->max_packet = transfer->dev->descdev.maxsize0;
+      err = grub_xhci_update_max_paket_size(x, transfer, priv->slotid, priv->max_packet);
+      if (err != GRUB_USB_ERR_NONE)
+        {
+          grub_dprintf("xhci", "%s: Updating max paket size failed\n", __func__);
+          return err;
+        }
+    }
+  if (epid == 1 &&
+      transfer->dev->descdev.class == 9 &&
+      transfer->dev->nports > 0)
+    {
+      err = grub_xhci_update_hub_portcount(x, transfer, priv->slotid);
+      if (err != GRUB_USB_ERR_NONE)
+        {
+          grub_dprintf("xhci", "%s: Updating max paket size failed\n", __func__);
+          return err;
+        }
+    }
+
+  /* Allocate private data for the transfer */
+  cdata = grub_zalloc(sizeof(*cdata));
+  if (!cdata)
+    return GRUB_USB_ERR_INTERNAL;
+
+  reqs = priv->enpoint_trbs[epid];
+
+  transfer->controller_data = cdata;
+
+  /* Now queue the transfer onto the TRB */
+  if (transfer->type == GRUB_USB_TRANSACTION_TYPE_CONTROL)
+  {
+    volatile struct grub_usb_packet_setup *setupdata;
+    setupdata = (void *)transfer->transactions[0].data;
+    grub_dprintf("xhci", "%s: CONTROLL TRANS req %d\n", __func__, setupdata->request);
+    grub_dprintf("xhci", "%s: CONTROLL TRANS length %d\n", __func__, setupdata->length);
+
+    if (setupdata && setupdata->request == GRUB_USB_REQ_SET_ADDRESS)
+      return GRUB_USB_ERR_NONE;
+
+    if (transfer->transcnt < 2)
+      return GRUB_USB_ERR_INTERNAL;
+
+    for (int i = 0; i < transfer->transcnt; i++)
+      {
+	grub_uint32_t flags = 0;
+	grub_uint64_t inline_data;
+	grub_usb_transaction_t tr = &transfer->transactions[i];
+
+	switch (tr->pid)
+	  {
+	    case GRUB_USB_TRANSFER_TYPE_SETUP:
+	      {
+		grub_dprintf("xhci", "%s: SETUP PKG\n", __func__);
+		grub_dprintf("xhci", "%s: transfer->size %d\n", __func__, transfer->size);
+		grub_dprintf("xhci", "%s: tr->size %d SETUP PKG\n", __func__, tr->size);
+
+		flags |= (TR_SETUP << 10);
+		flags |= TRB_TR_IDT;
+
+		if (transfer->size > 0)
+		  {
+		    if (grub_xhci_transfer_next_is_in(transfer, i))
+		      flags |= (3 << 16); /* TRT IN */
+		    else
+		      flags |= (2 << 16); /* TRT OUT */
+		  }
+		break;
+	      }
+	    case GRUB_USB_TRANSFER_TYPE_OUT:
+	      {
+		grub_dprintf("xhci", "%s: OUT PKG\n", __func__);
+		cdata->transfer_size += tr->size;
+		break;
+	      }
+	    case GRUB_USB_TRANSFER_TYPE_IN:
+	      {
+		grub_dprintf("xhci", "%s: IN PKG\n", __func__);
+		cdata->transfer_size += tr->size;
+		flags |= TRB_TR_DIR;
+		break;
+	      }
+	  }
+
+	if (grub_xhci_transfer_is_normal(transfer, i))
+	  flags |= (TR_NORMAL << 10);
+	else if (grub_xhci_transfer_is_data(transfer, i))
+	  flags |= (TR_DATA << 10);
+	else if (grub_xhci_transfer_is_zlp(transfer, i))
+	  flags |= (TR_STATUS << 10);
+
+	if (grub_xhci_transfer_next_is_normal(transfer, i))
+	  flags |= TRB_TR_CH;
+
+	if (grub_xhci_transfer_is_last(transfer, i))
+	  flags |= TRB_TR_IOC;
+
+	/* Assume the ring has enough free space for all TRBs */
+	if (flags & TRB_TR_IDT && tr->size <= (int)sizeof(inline_data))
+	  {
+	    grub_memcpy(&inline_data, (void *)tr->data, tr->size);
+	    xhci_trb_queue(reqs, inline_data, tr->size, flags);
+	  }
+	else
+	  {
+	    xhci_trb_queue(reqs, tr->data, tr->size, flags);
+	  }
+      }
+  }
+  else if (transfer->type == GRUB_USB_TRANSACTION_TYPE_BULK)
+    {
+      for (int i = 0; i < transfer->transcnt; i++)
+	{
+	  grub_uint32_t flags = (TR_NORMAL << 10);
+	  grub_usb_transaction_t tr = &transfer->transactions[i];
+	  switch (tr->pid)
+	    {
+	      case GRUB_USB_TRANSFER_TYPE_OUT:
+		{
+		  grub_dprintf("xhci", "%s: OUT PKG\n", __func__);
+		  cdata->transfer_size += tr->size;
+		  break;
+		}
+	      case GRUB_USB_TRANSFER_TYPE_IN:
+		{
+		  grub_dprintf("xhci", "%s: IN PKG\n", __func__);
+		  cdata->transfer_size += tr->size;
+		  flags |= TRB_TR_DIR;
+		  break;
+		}
+		case GRUB_USB_TRANSFER_TYPE_SETUP:
+		  break;
+	    }
+	  if (grub_xhci_transfer_is_last(transfer, i))
+	    flags |= TRB_TR_IOC;
+
+	  /* The ring might be to small, submit while adding new entries */
+	  rc = xhci_trb_queue_and_flush(x, priv->slotid, epid,
+				  reqs, tr->data, tr->size, flags);
+	  if (rc < 0)
+	    return GRUB_USB_ERR_TIMEOUT;
+	  else if (rc > 1)
+	    return grub_xhci_usb_to_grub_err(rc);
+
+	}
+    }
+  xhci_doorbell(x, priv->slotid, epid);
+
+  return GRUB_USB_ERR_NONE;
+}
+
+static grub_usb_err_t
+grub_xhci_check_transfer (grub_usb_controller_t dev,
+			  grub_usb_transfer_t transfer, grub_size_t * actual)
+{
+  grub_uint32_t status;
+  grub_uint32_t remaining;
+  grub_uint8_t epid;
+  volatile struct grub_xhci_ring *reqs;
+  grub_usb_err_t err;
+  int rc;
+
+  if (!dev->data || !transfer->controller_data || !transfer->dev ||
+      !transfer->dev->xhci_priv)
+    return GRUB_USB_ERR_INTERNAL;
+
+
+  struct grub_xhci_priv *priv = transfer->dev->xhci_priv;
+  struct grub_xhci *x = (struct grub_xhci *) dev->data;
+  struct grub_xhci_transfer_controller_data *cdata =
+    transfer->controller_data;
+
+  xhci_check_status(x);
+  xhci_process_events(x);
+
+  epid = grub_xhci_epid_from_transfer(transfer);
+
+  reqs = priv->enpoint_trbs[epid];
+
+  /* XXX: invalidate caches */
+
+  /* Get current status from event ring buffer */
+  status = (reqs->evt.status>> 24) & 0xff;
+  remaining = reqs->evt.status & 0xffffff;
+
+  if (status != CC_STOPPED_LENGTH_INVALID)
+      *actual = cdata->transfer_size - remaining;
+  else
+    *actual = 0;
+
+  if (xhci_ring_busy(reqs))
+      return GRUB_USB_ERR_WAIT;
+
+  grub_free(cdata);
+
+  grub_dprintf("xhci", "%s: xfer done\n", __func__);
+
+  err = grub_xhci_usb_to_grub_err(status);
+  if (err != GRUB_USB_ERR_NONE)
+    {
+      if (status == CC_STALL_ERROR)
+	{
+	  /* Clear the stall by resetting the endpoint */
+	  rc = xhci_cmd_reset_endpoint(x, priv->slotid, epid, 1);
+
+	  if (rc < 0)
+	    return GRUB_USB_ERR_TIMEOUT;
+
+	  return GRUB_USB_ERR_STALL;
+	}
+      else if (remaining > 0)
+	{
+	  return GRUB_USB_ERR_DATA;
+	}
+    }
+
+  return err;
+}
+
+static grub_usb_err_t
+grub_xhci_cancel_transfer (grub_usb_controller_t dev,
+			grub_usb_transfer_t transfer)
+{
+  grub_uint8_t epid;
+  volatile struct grub_xhci_ring *reqs;
+  struct grub_pci_dma_chunk *enpoint_trbs_dma;
+  grub_addr_t deque_pointer;
+  int rc;
+
+  if (!dev->data || !transfer->controller_data || !transfer->dev ||
+      !transfer->dev->xhci_priv)
+      return GRUB_USB_ERR_INTERNAL;
+
+  struct grub_xhci *x = (struct grub_xhci *) dev->data;
+  struct grub_xhci_transfer_controller_data *cdata =
+    transfer->controller_data;
+  struct grub_xhci_priv *priv = transfer->dev->xhci_priv;
+
+  epid = grub_xhci_epid_from_transfer(transfer);
+
+  enpoint_trbs_dma = priv->enpoint_trbs_dma[epid];
+  reqs = priv->enpoint_trbs[epid];
+
+  /* Abort current command */
+  rc = xhci_cmd_stop_endpoint(x, priv->slotid, epid, 0);
+  if (rc < 0)
+    return GRUB_USB_ERR_TIMEOUT;
+
+  /* Reset state */
+  reqs->nidx = 0;
+  reqs->eidx = 0;
+  reqs->cs = 1;
+
+  grub_arch_sync_dma_caches(reqs, sizeof(*reqs));
+
+  /* Reset the dequeue pointer to the begging of the TRB */
+  deque_pointer = grub_dma_get_phys(enpoint_trbs_dma);
+  rc = xhci_cmd_set_dequeue_pointer(x, priv->slotid, epid, deque_pointer| 1 );
+  if (rc < 0)
+    return GRUB_USB_ERR_TIMEOUT;
+
+  reqs->evt.ptr_low = 0;
+  reqs->evt.ptr_high = 0;
+  reqs->evt.control = 0;
+  reqs->evt.status = 0;
+
+  grub_arch_sync_dma_caches(reqs, sizeof(*reqs));
+
+  /* Restart ring buffer processing */
+  xhci_doorbell(x, priv->slotid, epid);
+
+  grub_free (cdata);
+
+  return GRUB_USB_ERR_NONE;
+}
+
+/****************************************************************
+ * xHCI port status functions
+ ****************************************************************/
+
+static int
+grub_xhci_hubports (grub_usb_controller_t dev)
+{
+  struct grub_xhci *x = (struct grub_xhci *) dev->data;
+  grub_uint32_t portinfo;
+
+  portinfo = x->ports;
+  grub_dprintf ("xhci", "root hub ports=%d\n", portinfo);
+  return portinfo;
+}
+
+static grub_usb_err_t
+grub_xhci_portstatus (grub_usb_controller_t dev,
+			  unsigned int port, unsigned int enable)
+{
+  struct grub_xhci *x = (struct grub_xhci *) dev->data;
+  grub_uint32_t portsc, pls;
+  grub_uint32_t end;
+
+  portsc = grub_xhci_port_read(x, port);
+  pls = xhci_get_field(portsc, XHCI_PORTSC_PLS);
+
+  grub_dprintf("xhci", "grub_xhci_portstatus port #%d: 0x%08x,%s%s pls %d enable %d\n",
+	       port, portsc,
+	       (portsc & GRUB_XHCI_PORTSC_PP)  ? " powered," : "",
+	       (portsc & GRUB_XHCI_PORTSC_PED) ? " enabled," : "",
+	       pls, enable);
+  xhci_check_status(x);
+
+  if ((enable && (portsc & GRUB_XHCI_PORTSC_PED)) ||
+      (!enable && !(portsc & GRUB_XHCI_PORTSC_PED)))
+    return GRUB_USB_ERR_NONE;
+
+  if (!enable)
+    {
+      /* Disable port */
+      grub_xhci_port_write(x, port, ~0, GRUB_XHCI_PORTSC_PED);
+      return GRUB_USB_ERR_NONE;
+    }
+
+  grub_dprintf ("xhci", "portstatus: XHCI STATUS: %08x\n",
+		grub_xhci_read32(&x->op->usbsts));
+  grub_dprintf ("xhci",
+		"portstatus: begin, iobase=%p, port=%d, status=0x%08x\n",
+		x->caps, port, portsc);
+
+  switch (pls)
+    {
+      case PLS_U0:
+	/* A USB3 port - controller automatically performs reset */
+	break;
+      case PLS_POLLING:
+	/* A USB2 port - perform device reset */
+	grub_xhci_port_write(x, port, ~GRUB_XHCI_PORTSC_PED, GRUB_XHCI_PORTSC_PR);
+	break;
+      default:
+        return GRUB_USB_ERR_NONE;
+    }
+
+  /* Wait for device to complete reset and be enabled */
+  end = grub_get_time_ms () + 100;
+  for (;;)
+    {
+      portsc = grub_xhci_port_read(x, port);
+      if (!(portsc & GRUB_XHCI_PORTSC_CCS))
+	{
+	  /* Device disconnected during reset */
+	  grub_dprintf ("xhci","ERROR: %s device disconnected\n", __func__);
+	  return GRUB_USB_ERR_BADDEVICE;
+	}
+      if (portsc & GRUB_XHCI_PORTSC_PED)
+	  /* Reset complete */
+	  break;
+      if (grub_get_time_ms () > end)
+	{
+	  grub_dprintf ("xhci","ERROR: %s TIMEOUT\n", __func__);
+	  return GRUB_USB_ERR_TIMEOUT;
+	}
+    }
+  xhci_check_status(x);
+
+  return GRUB_USB_ERR_NONE;
+}
+
+/****************************************************************
+ * xHCI detect device functions
+ ****************************************************************/
+
+static grub_usb_speed_t
+grub_xhci_detect_dev (grub_usb_controller_t dev, int port, int *changed)
+{
+  struct grub_xhci *x = (struct grub_xhci *) dev->data;
+  grub_uint32_t portsc, speed;
+
+  *changed = 0;
+  grub_dprintf("xhci", "%s: dev=%p USB%d_%d port %d\n", __func__, dev,
+	       x->psids[port-1].major, x->psids[port-1].minor, port);
+
+  /* On shutdown advertise all ports as disconnected. This will trigger
+   * a gracefull detatch. */
+  if (x->shutdown)
+    {
+      *changed = 1;
+      return GRUB_USB_SPEED_NONE;
+    }
+
+  /* Don't advertise new devices, connecting will fail if halted */
+  if (xhci_is_halted(x))
+    return GRUB_USB_SPEED_NONE;
+
+  portsc = grub_xhci_port_read(x, port);
+  speed = xhci_get_field(portsc, XHCI_PORTSC_SPEED);
+  grub_uint8_t pls = xhci_get_field(portsc, XHCI_PORTSC_PLS);
+
+  grub_dprintf("xhci", "grub_xhci_portstatus port #%d: 0x%08x,%s%s pls %d\n",
+	       port, portsc,
+	       (portsc & GRUB_XHCI_PORTSC_PP)  ? " powered," : "",
+	       (portsc & GRUB_XHCI_PORTSC_PED) ? " enabled," : "",
+	       pls);
+
+  /* Connect Status Change bit - it detects change of connection */
+  if (portsc & GRUB_XHCI_PORTSC_CSC)
+    {
+      *changed = 1;
+
+      grub_xhci_port_write(x, port, ~GRUB_XHCI_PORTSC_PED, GRUB_XHCI_PORTSC_CSC);
+    }
+
+  if (!(portsc & GRUB_XHCI_PORTSC_CCS))
+    return GRUB_USB_SPEED_NONE;
+
+  for (grub_uint8_t i = 0; i < 16 && x->psids[port-1].psids[i].id > 0; i++)
+    {
+      if (x->psids[port-1].psids[i].id == speed)
+        {
+	  grub_dprintf("xhci", "%s: grub_usb_speed = %d\n", __func__,
+		       x->psids[port-1].psids[i].grub_usb_speed );
+	  return x->psids[port-1].psids[i].grub_usb_speed;
+	}
+    }
+
+  return GRUB_USB_SPEED_NONE;
+}
+
+/****************************************************************
+ * xHCI attach/detach functions
+ ****************************************************************/
+
+static grub_usb_err_t
+grub_xhci_attach_dev (grub_usb_controller_t ctrl, grub_usb_device_t dev)
+{
+  struct grub_xhci *x = (struct grub_xhci *) ctrl->data;
+  grub_usb_err_t err;
+  grub_uint32_t max;
+
+  grub_dprintf("xhci", "%s: dev=%p\n", __func__, dev);
+
+  if (!dev || !x)
+    return GRUB_USB_ERR_INTERNAL;
+
+  dev->xhci_priv = grub_zalloc (sizeof (struct grub_xhci_priv));
+  if (!dev->xhci_priv)
+    return GRUB_USB_ERR_INTERNAL;
+
+
+  switch (dev->speed)
+    {
+      case GRUB_USB_SPEED_LOW:
+	{
+	  max = 8;
+	  break;
+	}
+      case GRUB_USB_SPEED_FULL:
+      case GRUB_USB_SPEED_HIGH:
+	{
+	  max = 64;
+	  break;
+	}
+      case GRUB_USB_SPEED_SUPER:
+	{
+	  max = 512;
+	  break;
+	}
+      default:
+      case GRUB_USB_SPEED_NONE:
+	{
+	  max = 0;
+	}
+    }
+
+  /* Assign a slot, assign an address and configure endpoint 0 */
+  err = grub_xhci_prepare_endpoint(x, dev,
+				  0,
+				  0,
+				  GRUB_USB_TRANSACTION_TYPE_CONTROL,
+				  max,
+				  dev->xhci_priv);
+
+  return err;
+}
+
+static grub_usb_err_t
+grub_xhci_detach_dev (grub_usb_controller_t ctrl, grub_usb_device_t dev)
+{
+  struct grub_xhci *x = (struct grub_xhci *) ctrl->data;
+  struct grub_xhci_priv *priv;
+  int cc = CC_SUCCESS;
+
+  grub_dprintf("xhci", "%s: dev=%p\n", __func__, dev);
+
+  if (!dev)
+    return GRUB_USB_ERR_INTERNAL;
+
+  if (dev->xhci_priv)
+    {
+      priv = dev->xhci_priv;
+      /* Stop endpoints and free ring buffer */
+      for (int i = 0; i < GRUB_XHCI_MAX_ENDPOINTS; i++)
+	{
+	  if (priv->enpoint_trbs[i] != NULL)
+	    {
+	      cc = xhci_cmd_stop_endpoint(x, priv->slotid, i, 1);
+	      if (cc != CC_SUCCESS)
+		grub_dprintf("xhci", "Failed to disable EP%d on slot %d\n", i,
+			     priv->slotid);
+
+	      grub_dprintf("xhci", "grub_dma_free[%d]\n", i);
+
+	      grub_dma_free(priv->enpoint_trbs_dma[i]);
+	      priv->enpoint_trbs[i] = NULL;
+	      priv->enpoint_trbs_dma[i] = NULL;
+	    }
+	}
+
+      cc = xhci_cmd_disable_slot(x, priv->slotid);
+      if (cc == CC_SUCCESS)
+	{
+	  if (priv->slotctx_dma)
+	    grub_dma_free(priv->slotctx_dma);
+	  x->devs[priv->slotid].ptr_low = 0;
+	  x->devs[priv->slotid].ptr_high = 0;
+	  grub_arch_sync_dma_caches(&x->devs[priv->slotid], sizeof(x->devs[0]));
+	}
+	else
+	  grub_dprintf("xhci", "Failed to disable slot %d\n", priv->slotid);
+
+      grub_free(dev->xhci_priv);
+    }
+
+  dev->xhci_priv = NULL;
+
+  if (cc != CC_SUCCESS)
+    return GRUB_USB_ERR_BADDEVICE;
+  return GRUB_USB_ERR_NONE;
+}
+
+/****************************************************************
+ * xHCI terminate functions
+ ****************************************************************/
+
+static void
+grub_xhci_halt(struct grub_xhci *x)
+{
+  grub_uint32_t reg;
+
+  /* Halt the command ring */
+  reg = grub_xhci_read32(&x->op->crcr_low);
+  grub_xhci_write32(&x->op->crcr_low, reg | 4);
+
+  int rc = xhci_event_wait(x, x->cmds, 100);
+  grub_dprintf("xhci", "%s: xhci_event_wait = %d\n", __func__, rc);
+  if (rc < 0)
+    return;
+
+  /* Stop the controller */
+  reg = grub_xhci_read32(&x->op->usbcmd);
+  if (reg & GRUB_XHCI_CMD_RS)
+    {
+      reg &= ~GRUB_XHCI_CMD_RS;
+      grub_xhci_write32(&x->op->usbcmd, reg);
+    }
+
+  return;
+}
+
+static grub_err_t
+grub_xhci_fini_hw (int noreturn __attribute__ ((unused)))
+{
+  struct grub_xhci *x;
+
+  /* We should disable all XHCI HW to prevent any DMA access etc. */
+  for (x = xhci; x; x = x->next)
+    {
+      x->shutdown = 1;
+
+      /* Gracefully detach active devices */
+      grub_usb_poll_devices(0);
+
+      /* Check if xHCI is halted and halt it if not */
+      grub_xhci_halt (x);
+
+      /* Reset xHCI */
+      if (grub_xhci_reset (x) != GRUB_USB_ERR_NONE)
+	return GRUB_ERR_BAD_DEVICE;
+    }
+
+  return GRUB_ERR_NONE;
+}
+
+static struct grub_usb_controller_dev usb_controller = {
+  .name = "xhci",
+  .iterate = grub_xhci_iterate,
+  .setup_transfer = grub_xhci_setup_transfer,
+  .check_transfer = grub_xhci_check_transfer,
+  .cancel_transfer = grub_xhci_cancel_transfer,
+  .hubports = grub_xhci_hubports,
+  .portstatus = grub_xhci_portstatus,
+  .detect_dev = grub_xhci_detect_dev,
+  .attach_dev = grub_xhci_attach_dev,
+  .detach_dev = grub_xhci_detach_dev,
+  /* estimated max. count of TDs for one bulk transfer */
+  .max_bulk_tds = GRUB_XHCI_RING_ITEMS - 3
+};
+
+GRUB_MOD_INIT (xhci)
+{
+  grub_stop_disk_firmware ();
+
+  grub_boot_time ("Initing XHCI hardware");
+  grub_xhci_pci_scan ();
+  grub_boot_time ("Registering XHCI driver");
+  grub_usb_controller_dev_register (&usb_controller);
+  grub_boot_time ("XHCI driver registered");
+}
+
+GRUB_MOD_FINI (xhci)
+{
+  grub_xhci_fini_hw (0);
+  grub_usb_controller_dev_unregister (&usb_controller);
+}
diff --git a/include/grub/usb.h b/include/grub/usb.h
index 609faf7d0..eb71fa1c7 100644
--- a/include/grub/usb.h
+++ b/include/grub/usb.h
@@ -338,6 +338,10 @@ grub_usb_cancel_transfer (grub_usb_transfer_t trans);
 void
 grub_ehci_init_device (volatile void *regs);
 void
+grub_xhci_init_device (volatile void *regs);
+void
 grub_ehci_pci_scan (void);
+void
+grub_xhci_pci_scan (void);
 
 #endif /* GRUB_USB_H */
-- 
2.39.2