usb: xhci: Add debugfs interface for xHCI driver

This adds debugfs consumer for xHCI driver. The debugfs entries
read all host registers, device/endpoint contexts, command ring,
event ring and various endpoint rings. With these entries, users
can check the registers and memory spaces used by a host during
run time, or save all the information with a simple 'cp -r' for
post-mortem programs.

The file hierarchy looks like this.

[root of debugfs]
|__usb
|____[e,u,o]hci                 <---------[root for other HCIs]
|____xhci                       <---------------[root for xHCI]
|______0000:00:14.0             <--------------[xHCI host name]
|________reg-cap                <--------[capability registers]
|________reg-op                 <-------[operational registers]
|________reg-runtime            <-----------[runtime registers]
|________reg-ext-#cap_name      <----[extended capability regs]
|________command-ring           <-------[root for command ring]
|__________cycle                <------------------[ring cycle]
|__________dequeue              <--------[ring dequeue pointer]
|__________enqueue              <--------[ring enqueue pointer]
|__________trbs                 <-------------------[ring trbs]
|________event-ring             <---------[root for event ring]
|__________cycle                <------------------[ring cycle]
|__________dequeue              <--------[ring dequeue pointer]
|__________enqueue              <--------[ring enqueue pointer]
|__________trbs                 <-------------------[ring trbs]
|________devices                <------------[root for devices]
|__________#slot_id             <-----------[root for a device]
|____________name               <-----------------[device name]
|____________slot-context       <----------------[slot context]
|____________ep-context         <-----------[endpoint contexts]
|____________ep#ep_index        <--------[root for an endpoint]
|______________cycle            <------------------[ring cycle]
|______________dequeue          <--------[ring dequeue pointer]
|______________enqueue          <--------[ring enqueue pointer]
|______________trbs             <-------------------[ring trbs]
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/Makefile

@@ -25,6 +25,10 @@ ifneq ($(CONFIG_USB_XHCI_RCAR), )
 	xhci-plat-hcd-y		+= xhci-rcar.o
 endif
 
+ifneq ($(CONFIG_DEBUG_FS),)
+	xhci-hcd-y		+= xhci-debugfs.o
+endif
+
 obj-$(CONFIG_USB_WHCI_HCD)	+= whci/
 
 obj-$(CONFIG_USB_PCI)	+= pci-quirks.o

drivers/usb/host/xhci-debugfs.c

+/*
+ * xhci-debugfs.c - xHCI debugfs interface
+ *
+ * Copyright (C) 2017 Intel Corporation
+ *
+ * Author: Lu Baolu <baolu.lu@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/slab.h>
+
+#include "xhci.h"
+#include "xhci-debugfs.h"
+
+static const struct debugfs_reg32 xhci_cap_regs[] = {
+	dump_register(CAPLENGTH),
+	dump_register(HCSPARAMS1),
+	dump_register(HCSPARAMS2),
+	dump_register(HCSPARAMS3),
+	dump_register(HCCPARAMS1),
+	dump_register(DOORBELLOFF),
+	dump_register(RUNTIMEOFF),
+	dump_register(HCCPARAMS2),
+};
+
+static const struct debugfs_reg32 xhci_op_regs[] = {
+	dump_register(USBCMD),
+	dump_register(USBSTS),
+	dump_register(PAGESIZE),
+	dump_register(DNCTRL),
+	dump_register(CRCR),
+	dump_register(DCBAAP_LOW),
+	dump_register(DCBAAP_HIGH),
+	dump_register(CONFIG),
+};
+
+static const struct debugfs_reg32 xhci_runtime_regs[] = {
+	dump_register(MFINDEX),
+	dump_register(IR0_IMAN),
+	dump_register(IR0_IMOD),
+	dump_register(IR0_ERSTSZ),
+	dump_register(IR0_ERSTBA_LOW),
+	dump_register(IR0_ERSTBA_HIGH),
+	dump_register(IR0_ERDP_LOW),
+	dump_register(IR0_ERDP_HIGH),
+};
+
+static const struct debugfs_reg32 xhci_extcap_legsup[] = {
+	dump_register(EXTCAP_USBLEGSUP),
+	dump_register(EXTCAP_USBLEGCTLSTS),
+};
+
+static const struct debugfs_reg32 xhci_extcap_protocol[] = {
+	dump_register(EXTCAP_REVISION),
+	dump_register(EXTCAP_NAME),
+	dump_register(EXTCAP_PORTINFO),
+	dump_register(EXTCAP_PORTTYPE),
+	dump_register(EXTCAP_MANTISSA1),
+	dump_register(EXTCAP_MANTISSA2),
+	dump_register(EXTCAP_MANTISSA3),
+	dump_register(EXTCAP_MANTISSA4),
+	dump_register(EXTCAP_MANTISSA5),
+	dump_register(EXTCAP_MANTISSA6),
+};
+
+static const struct debugfs_reg32 xhci_extcap_dbc[] = {
+	dump_register(EXTCAP_DBC_CAPABILITY),
+	dump_register(EXTCAP_DBC_DOORBELL),
+	dump_register(EXTCAP_DBC_ERSTSIZE),
+	dump_register(EXTCAP_DBC_ERST_LOW),
+	dump_register(EXTCAP_DBC_ERST_HIGH),
+	dump_register(EXTCAP_DBC_ERDP_LOW),
+	dump_register(EXTCAP_DBC_ERDP_HIGH),
+	dump_register(EXTCAP_DBC_CONTROL),
+	dump_register(EXTCAP_DBC_STATUS),
+	dump_register(EXTCAP_DBC_PORTSC),
+	dump_register(EXTCAP_DBC_CONT_LOW),
+	dump_register(EXTCAP_DBC_CONT_HIGH),
+	dump_register(EXTCAP_DBC_DEVINFO1),
+	dump_register(EXTCAP_DBC_DEVINFO2),
+};
+
+static struct dentry *xhci_debugfs_root;
+
+static struct xhci_regset *xhci_debugfs_alloc_regset(struct xhci_hcd *xhci)
+{
+	struct xhci_regset	*regset;
+
+	regset = kzalloc(sizeof(*regset), GFP_KERNEL);
+	if (!regset)
+		return NULL;
+
+	/*
+	 * The allocation and free of regset are executed in order.
+	 * We needn't a lock here.
+	 */
+	INIT_LIST_HEAD(&regset->list);
+	list_add_tail(&regset->list, &xhci->regset_list);
+
+	return regset;
+}
+
+static void xhci_debugfs_free_regset(struct xhci_regset *regset)
+{
+	if (!regset)
+		return;
+
+	list_del(&regset->list);
+	kfree(regset);
+}
+
+static void xhci_debugfs_regset(struct xhci_hcd *xhci, u32 base,
+				const struct debugfs_reg32 *regs,
+				size_t nregs, struct dentry *parent,
+				const char *fmt, ...)
+{
+	struct xhci_regset	*rgs;
+	va_list			args;
+	struct debugfs_regset32	*regset;
+	struct usb_hcd		*hcd = xhci_to_hcd(xhci);
+
+	rgs = xhci_debugfs_alloc_regset(xhci);
+	if (!rgs)
+		return;
+
+	va_start(args, fmt);
+	vsnprintf(rgs->name, sizeof(rgs->name), fmt, args);
+	va_end(args);
+
+	regset = &rgs->regset;
+	regset->regs = regs;
+	regset->nregs = nregs;
+	regset->base = hcd->regs + base;
+
+	debugfs_create_regset32((const char *)rgs->name, 0444, parent, regset);
+}
+
+static void xhci_debugfs_extcap_regset(struct xhci_hcd *xhci, int cap_id,
+				       const struct debugfs_reg32 *regs,
+				       size_t n, const char *cap_name)
+{
+	u32			offset;
+	int			index = 0;
+	size_t			psic, nregs = n;
+	void __iomem		*base = &xhci->cap_regs->hc_capbase;
+
+	offset = xhci_find_next_ext_cap(base, 0, cap_id);
+	while (offset) {
+		if (cap_id == XHCI_EXT_CAPS_PROTOCOL) {
+			psic = XHCI_EXT_PORT_PSIC(readl(base + offset + 8));
+			nregs = min(4 + psic, n);
+		}
+
+		xhci_debugfs_regset(xhci, offset, regs, nregs,
+				    xhci->debugfs_root, "%s:%02d",
+				    cap_name, index);
+		offset = xhci_find_next_ext_cap(base, offset, cap_id);
+		index++;
+	}
+}
+
+static int xhci_ring_enqueue_show(struct seq_file *s, void *unused)
+{
+	dma_addr_t		dma;
+	struct xhci_ring	*ring = s->private;
+
+	dma = xhci_trb_virt_to_dma(ring->enq_seg, ring->enqueue);
+	seq_printf(s, "%pad\n", &dma);
+
+	return 0;
+}
+
+static int xhci_ring_dequeue_show(struct seq_file *s, void *unused)
+{
+	dma_addr_t		dma;
+	struct xhci_ring	*ring = s->private;
+
+	dma = xhci_trb_virt_to_dma(ring->deq_seg, ring->dequeue);
+	seq_printf(s, "%pad\n", &dma);
+
+	return 0;
+}
+
+static int xhci_ring_cycle_show(struct seq_file *s, void *unused)
+{
+	struct xhci_ring	*ring = s->private;
+
+	seq_printf(s, "%d\n", ring->cycle_state);
+
+	return 0;
+}
+
+static void xhci_ring_dump_segment(struct seq_file *s,
+				   struct xhci_segment *seg)
+{
+	int			i;
+	dma_addr_t		dma;
+	union xhci_trb		*trb;
+
+	for (i = 0; i < TRBS_PER_SEGMENT; i++) {
+		trb = &seg->trbs[i];
+		dma = seg->dma + i * sizeof(*trb);
+		seq_printf(s, "%pad: %s\n", &dma,
+			   xhci_decode_trb(trb->generic.field[0],
+					   trb->generic.field[1],
+					   trb->generic.field[2],
+					   trb->generic.field[3]));
+	}
+}
+
+static int xhci_ring_trb_show(struct seq_file *s, void *unused)
+{
+	int			i;
+	struct xhci_ring	*ring = s->private;
+	struct xhci_segment	*seg = ring->first_seg;
+
+	for (i = 0; i < ring->num_segs; i++) {
+		xhci_ring_dump_segment(s, seg);
+		seg = seg->next;
+	}
+
+	return 0;
+}
+
+static struct xhci_file_map ring_files[] = {
+	{"enqueue",		xhci_ring_enqueue_show, },
+	{"dequeue",		xhci_ring_dequeue_show, },
+	{"cycle",		xhci_ring_cycle_show, },
+	{"trbs",		xhci_ring_trb_show, },
+};
+
+static int xhci_ring_open(struct inode *inode, struct file *file)
+{
+	int			i;
+	struct xhci_file_map	*f_map;
+	const char		*file_name = file_dentry(file)->d_iname;
+
+	for (i = 0; i < ARRAY_SIZE(ring_files); i++) {
+		f_map = &ring_files[i];
+
+		if (strcmp(f_map->name, file_name) == 0)
+			break;
+	}
+
+	return single_open(file, f_map->show, inode->i_private);
+}
+
+static const struct file_operations xhci_ring_fops = {
+	.open			= xhci_ring_open,
+	.read			= seq_read,
+	.llseek			= seq_lseek,
+	.release		= single_release,
+};
+
+static int xhci_slot_context_show(struct seq_file *s, void *unused)
+{
+	struct xhci_hcd		*xhci;
+	struct xhci_slot_ctx	*slot_ctx;
+	struct xhci_slot_priv	*priv = s->private;
+	struct xhci_virt_device	*dev = priv->dev;
+
+	xhci = hcd_to_xhci(bus_to_hcd(dev->udev->bus));
+	slot_ctx = xhci_get_slot_ctx(xhci, dev->out_ctx);
+	seq_printf(s, "%pad: %s\n", &dev->out_ctx->dma,
+		   xhci_decode_slot_context(slot_ctx->dev_info,
+					    slot_ctx->dev_info2,
+					    slot_ctx->tt_info,
+					    slot_ctx->dev_state));
+
+	return 0;
+}
+
+static int xhci_endpoint_context_show(struct seq_file *s, void *unused)
+{
+	int			dci;
+	dma_addr_t		dma;
+	struct xhci_hcd		*xhci;
+	struct xhci_ep_ctx	*ep_ctx;
+	struct xhci_slot_priv	*priv = s->private;
+	struct xhci_virt_device	*dev = priv->dev;
+
+	xhci = hcd_to_xhci(bus_to_hcd(dev->udev->bus));
+
+	for (dci = 1; dci < 32; dci++) {
+		ep_ctx = xhci_get_ep_ctx(xhci, dev->out_ctx, dci);
+		dma = dev->out_ctx->dma + dci * CTX_SIZE(xhci->hcc_params);
+		seq_printf(s, "%pad: %s\n", &dma,
+			   xhci_decode_ep_context(ep_ctx->ep_info,
+						  ep_ctx->ep_info2,
+						  ep_ctx->deq,
+						  ep_ctx->tx_info));
+	}
+
+	return 0;
+}
+
+static int xhci_device_name_show(struct seq_file *s, void *unused)
+{
+	struct xhci_slot_priv	*priv = s->private;
+	struct xhci_virt_device	*dev = priv->dev;
+
+	seq_printf(s, "%s\n", dev_name(&dev->udev->dev));
+
+	return 0;
+}
+
+static struct xhci_file_map context_files[] = {
+	{"name",		xhci_device_name_show, },
+	{"slot-context",	xhci_slot_context_show, },
+	{"ep-context",		xhci_endpoint_context_show, },
+};
+
+static int xhci_context_open(struct inode *inode, struct file *file)
+{
+	int			i;
+	struct xhci_file_map	*f_map;
+	const char		*file_name = file_dentry(file)->d_iname;
+
+	for (i = 0; i < ARRAY_SIZE(context_files); i++) {
+		f_map = &context_files[i];
+
+		if (strcmp(f_map->name, file_name) == 0)
+			break;
+	}
+
+	return single_open(file, f_map->show, inode->i_private);
+}
+
+static const struct file_operations xhci_context_fops = {
+	.open			= xhci_context_open,
+	.read			= seq_read,
+	.llseek			= seq_lseek,
+	.release		= single_release,
+};
+
+static void xhci_debugfs_create_files(struct xhci_hcd *xhci,
+				      struct xhci_file_map *files,
+				      size_t nentries, void *data,
+				      struct dentry *parent,
+				      const struct file_operations *fops)
+{
+	int			i;
+
+	for (i = 0; i < nentries; i++)
+		debugfs_create_file(files[i].name, 0444, parent, data, fops);
+}
+
+static struct dentry *xhci_debugfs_create_ring_dir(struct xhci_hcd *xhci,
+						   struct xhci_ring *ring,
+						   const char *name,
+						   struct dentry *parent)
+{
+	struct dentry		*dir;
+
+	dir = debugfs_create_dir(name, parent);
+	xhci_debugfs_create_files(xhci, ring_files, ARRAY_SIZE(ring_files),
+				  ring, dir, &xhci_ring_fops);
+
+	return dir;
+}
+
+static void xhci_debugfs_create_context_files(struct xhci_hcd *xhci,
+					      struct dentry *parent,
+					      int slot_id)
+{
+	struct xhci_virt_device	*dev = xhci->devs[slot_id];
+
+	xhci_debugfs_create_files(xhci, context_files,
+				  ARRAY_SIZE(context_files),
+				  dev->debugfs_private,
+				  parent, &xhci_context_fops);
+}
+
+void xhci_debugfs_create_endpoint(struct xhci_hcd *xhci,
+				  struct xhci_virt_device *dev,
+				  int ep_index)
+{
+	struct xhci_ep_priv	*epriv;
+	struct xhci_slot_priv	*spriv = dev->debugfs_private;
+
+	if (spriv->eps[ep_index])
+		return;
+
+	epriv = kzalloc(sizeof(*epriv), GFP_KERNEL);
+	if (!epriv)
+		return;
+
+	snprintf(epriv->name, sizeof(epriv->name), "ep%02d", ep_index);
+	epriv->root = xhci_debugfs_create_ring_dir(xhci,
+						   dev->eps[ep_index].new_ring,
+						   epriv->name,
+						   spriv->root);
+	spriv->eps[ep_index] = epriv;
+}
+
+void xhci_debugfs_remove_endpoint(struct xhci_hcd *xhci,
+				  struct xhci_virt_device *dev,
+				  int ep_index)
+{
+	struct xhci_ep_priv	*epriv;
+	struct xhci_slot_priv	*spriv = dev->debugfs_private;
+
+	if (!spriv || !spriv->eps[ep_index])
+		return;
+
+	epriv = spriv->eps[ep_index];
+	debugfs_remove_recursive(epriv->root);
+	spriv->eps[ep_index] = NULL;
+	kfree(epriv);
+}
+
+void xhci_debugfs_create_slot(struct xhci_hcd *xhci, int slot_id)
+{
+	struct xhci_slot_priv	*priv;
+	struct xhci_virt_device	*dev = xhci->devs[slot_id];
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return;
+
+	snprintf(priv->name, sizeof(priv->name), "%02d", slot_id);
+	priv->root = debugfs_create_dir(priv->name, xhci->debugfs_slots);
+	priv->dev = dev;
+	dev->debugfs_private = priv;
+
+	xhci_debugfs_create_ring_dir(xhci, dev->eps[0].ring,
+				     "ep00", priv->root);
+
+	xhci_debugfs_create_context_files(xhci, priv->root, slot_id);
+}
+
+void xhci_debugfs_remove_slot(struct xhci_hcd *xhci, int slot_id)
+{
+	int			i;
+	struct xhci_slot_priv	*priv;
+	struct xhci_virt_device	*dev = xhci->devs[slot_id];
+
+	if (!dev || !dev->debugfs_private)
+		return;
+
+	priv = dev->debugfs_private;
+
+	debugfs_remove_recursive(priv->root);
+
+	for (i = 0; i < 31; i++)
+		kfree(priv->eps[i]);
+
+	kfree(priv);
+	dev->debugfs_private = NULL;
+}
+
+void xhci_debugfs_init(struct xhci_hcd *xhci)
+{
+	struct device		*dev = xhci_to_hcd(xhci)->self.controller;
+
+	xhci->debugfs_root = debugfs_create_dir(dev_name(dev),
+						xhci_debugfs_root);
+
+	INIT_LIST_HEAD(&xhci->regset_list);
+
+	xhci_debugfs_regset(xhci,
+			    0,
+			    xhci_cap_regs, ARRAY_SIZE(xhci_cap_regs),
+			    xhci->debugfs_root, "reg-cap");
+
+	xhci_debugfs_regset(xhci,
+			    HC_LENGTH(readl(&xhci->cap_regs->hc_capbase)),
+			    xhci_op_regs, ARRAY_SIZE(xhci_op_regs),
+			    xhci->debugfs_root, "reg-op");
+
+	xhci_debugfs_regset(xhci,
+			    readl(&xhci->cap_regs->run_regs_off) & RTSOFF_MASK,
+			    xhci_runtime_regs, ARRAY_SIZE(xhci_runtime_regs),
+			    xhci->debugfs_root, "reg-runtime");
+
+	xhci_debugfs_extcap_regset(xhci, XHCI_EXT_CAPS_LEGACY,
+				   xhci_extcap_legsup,
+				   ARRAY_SIZE(xhci_extcap_legsup),
+				   "reg-ext-legsup");
+
+	xhci_debugfs_extcap_regset(xhci, XHCI_EXT_CAPS_PROTOCOL,
+				   xhci_extcap_protocol,
+				   ARRAY_SIZE(xhci_extcap_protocol),
+				   "reg-ext-protocol");
+
+	xhci_debugfs_extcap_regset(xhci, XHCI_EXT_CAPS_DEBUG,
+				   xhci_extcap_dbc,
+				   ARRAY_SIZE(xhci_extcap_dbc),
+				   "reg-ext-dbc");
+
+	xhci_debugfs_create_ring_dir(xhci, xhci->cmd_ring,
+				     "command-ring",
+				     xhci->debugfs_root);
+
+	xhci_debugfs_create_ring_dir(xhci, xhci->event_ring,
+				     "event-ring",
+				     xhci->debugfs_root);
+
+	xhci->debugfs_slots = debugfs_create_dir("devices", xhci->debugfs_root);
+}
+
+void xhci_debugfs_exit(struct xhci_hcd *xhci)
+{
+	struct xhci_regset	*rgs, *tmp;
+
+	debugfs_remove_recursive(xhci->debugfs_root);
+	xhci->debugfs_root = NULL;
+	xhci->debugfs_slots = NULL;
+
+	list_for_each_entry_safe(rgs, tmp, &xhci->regset_list, list)
+		xhci_debugfs_free_regset(rgs);
+}
+
+void __init xhci_debugfs_create_root(void)
+{
+	xhci_debugfs_root = debugfs_create_dir("xhci", usb_debug_root);
+}
+
+void __exit xhci_debugfs_remove_root(void)
+{
+	debugfs_remove_recursive(xhci_debugfs_root);
+	xhci_debugfs_root = NULL;
+}

drivers/usb/host/xhci-debugfs.h

+/*
+ * xhci-debugfs.h - xHCI debugfs interface
+ *
+ * Copyright (C) 2017 Intel Corporation
+ *
+ * Author: Lu Baolu <baolu.lu@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __LINUX_XHCI_DEBUGFS_H
+#define __LINUX_XHCI_DEBUGFS_H
+
+#include <linux/debugfs.h>
+
+#define DEBUGFS_NAMELEN 32
+
+#define REG_CAPLENGTH					0x00
+#define REG_HCSPARAMS1					0x04
+#define REG_HCSPARAMS2					0x08
+#define REG_HCSPARAMS3					0x0c
+#define REG_HCCPARAMS1					0x10
+#define REG_DOORBELLOFF					0x14
+#define REG_RUNTIMEOFF					0x18
+#define REG_HCCPARAMS2					0x1c
+
+#define	REG_USBCMD					0x00
+#define REG_USBSTS					0x04
+#define REG_PAGESIZE					0x08
+#define REG_DNCTRL					0x14
+#define REG_CRCR					0x18
+#define REG_DCBAAP_LOW					0x30
+#define REG_DCBAAP_HIGH					0x34
+#define REG_CONFIG					0x38
+
+#define REG_MFINDEX					0x00
+#define REG_IR0_IMAN					0x20
+#define REG_IR0_IMOD					0x24
+#define REG_IR0_ERSTSZ					0x28
+#define REG_IR0_ERSTBA_LOW				0x30
+#define REG_IR0_ERSTBA_HIGH				0x34
+#define REG_IR0_ERDP_LOW				0x38
+#define REG_IR0_ERDP_HIGH				0x3c
+
+#define REG_EXTCAP_USBLEGSUP				0x00
+#define REG_EXTCAP_USBLEGCTLSTS				0x04
+
+#define REG_EXTCAP_REVISION				0x00
+#define REG_EXTCAP_NAME					0x04
+#define REG_EXTCAP_PORTINFO				0x08
+#define REG_EXTCAP_PORTTYPE				0x0c
+#define REG_EXTCAP_MANTISSA1				0x10
+#define REG_EXTCAP_MANTISSA2				0x14
+#define REG_EXTCAP_MANTISSA3				0x18
+#define REG_EXTCAP_MANTISSA4				0x1c
+#define REG_EXTCAP_MANTISSA5				0x20
+#define REG_EXTCAP_MANTISSA6				0x24
+
+#define REG_EXTCAP_DBC_CAPABILITY			0x00
+#define REG_EXTCAP_DBC_DOORBELL				0x04
+#define REG_EXTCAP_DBC_ERSTSIZE				0x08
+#define REG_EXTCAP_DBC_ERST_LOW				0x10
+#define REG_EXTCAP_DBC_ERST_HIGH			0x14
+#define REG_EXTCAP_DBC_ERDP_LOW				0x18
+#define REG_EXTCAP_DBC_ERDP_HIGH			0x1c
+#define REG_EXTCAP_DBC_CONTROL				0x20
+#define REG_EXTCAP_DBC_STATUS				0x24
+#define REG_EXTCAP_DBC_PORTSC				0x28
+#define REG_EXTCAP_DBC_CONT_LOW				0x30
+#define REG_EXTCAP_DBC_CONT_HIGH			0x34
+#define REG_EXTCAP_DBC_DEVINFO1				0x38
+#define REG_EXTCAP_DBC_DEVINFO2				0x3c
+
+#define dump_register(nm)				\
+{							\
+	.name	= __stringify(nm),			\
+	.offset	= REG_ ##nm,				\
+}
+
+struct xhci_regset {
+	char			name[DEBUGFS_NAMELEN];
+	struct debugfs_regset32	regset;
+	size_t			nregs;
+	struct dentry		*parent;
+	struct list_head	list;
+};
+
+struct xhci_file_map {
+	const char		*name;
+	int			(*show)(struct seq_file *s, void *unused);
+};
+
+struct xhci_ep_priv {
+	char			name[DEBUGFS_NAMELEN];
+	struct dentry		*root;
+};
+
+struct xhci_slot_priv {
+	char			name[DEBUGFS_NAMELEN];
+	struct dentry		*root;
+	struct xhci_ep_priv	*eps[31];
+	struct xhci_virt_device	*dev;
+};
+
+#ifdef CONFIG_DEBUG_FS
+void xhci_debugfs_init(struct xhci_hcd *xhci);
+void xhci_debugfs_exit(struct xhci_hcd *xhci);
+void __init xhci_debugfs_create_root(void);
+void __exit xhci_debugfs_remove_root(void);
+void xhci_debugfs_create_slot(struct xhci_hcd *xhci, int slot_id);
+void xhci_debugfs_remove_slot(struct xhci_hcd *xhci, int slot_id);
+void xhci_debugfs_create_endpoint(struct xhci_hcd *xhci,
+				  struct xhci_virt_device *virt_dev,
+				  int ep_index);
+void xhci_debugfs_remove_endpoint(struct xhci_hcd *xhci,
+				  struct xhci_virt_device *virt_dev,
+				  int ep_index);
+#else
+static inline void xhci_debugfs_init(struct xhci_hcd *xhci) { }
+static inline void xhci_debugfs_exit(struct xhci_hcd *xhci) { }
+static inline void __init xhci_debugfs_create_root(void) { }
+static inline void __exit xhci_debugfs_remove_root(void) { }
+static inline void xhci_debugfs_create_slot(struct xhci_hcd *x, int s) { }
+static inline void xhci_debugfs_remove_slot(struct xhci_hcd *x, int s) { }
+static inline void
+xhci_debugfs_create_endpoint(struct xhci_hcd *xhci,
+			     struct xhci_virt_device *virt_dev,
+			     int ep_index) { }
+static inline void
+xhci_debugfs_remove_endpoint(struct xhci_hcd *xhci,
+			     struct xhci_virt_device *virt_dev,
+			     int ep_index) { }
+#endif /* CONFIG_DEBUG_FS */
+
+#endif /* __LINUX_XHCI_DEBUGFS_H */

drivers/usb/host/xhci-mem.c

@@ -28,6 +28,7 @@
 
 #include "xhci.h"
 #include "xhci-trace.h"
+#include "xhci-debugfs.h"
 
 /*
  * Allocates a generic ring segment from the ring pool, sets the dma address,
@@ -465,8 +466,6 @@ int xhci_ring_expansion(struct xhci_hcd *xhci, struct xhci_ring *ring,
 	return 0;
 }
 
-#define CTX_SIZE(_hcc) (HCC_64BYTE_CONTEXT(_hcc) ? 64 : 32)
-
 static struct xhci_container_ctx *xhci_alloc_container_ctx(struct xhci_hcd *xhci,
 						    int type, gfp_t flags)
 {
@@ -961,6 +960,7 @@ void xhci_free_virt_devices_depth_first(struct xhci_hcd *xhci, int slot_id)
 		}
 	}
 	/* we are now at a leaf device */
+	xhci_debugfs_remove_slot(xhci, slot_id);
 	xhci_free_virt_device(xhci, slot_id);
 }
 
@@ -1496,7 +1496,6 @@ int xhci_endpoint_init(struct xhci_hcd *xhci,
 	ep_ctx->tx_info = cpu_to_le32(EP_MAX_ESIT_PAYLOAD_LO(max_esit_payload) |
 				      EP_AVG_TRB_LENGTH(avg_trb_len));
 
-	/* FIXME Debug endpoint context */
 	return 0;
 }
 

drivers/usb/host/xhci.c

@@ -32,6 +32,7 @@
 #include "xhci.h"
 #include "xhci-trace.h"
 #include "xhci-mtk.h"
+#include "xhci-debugfs.h"
 
 #define DRIVER_AUTHOR "Sarah Sharp"
 #define DRIVER_DESC "'eXtensible' Host Controller (xHC) Driver"
@@ -632,6 +633,9 @@ int xhci_run(struct usb_hcd *hcd)
 	}
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
 			"Finished xhci_run for USB2 roothub");
+
+	xhci_debugfs_init(xhci);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(xhci_run);
@@ -660,6 +664,8 @@ static void xhci_stop(struct usb_hcd *hcd)
 		return;
 	}
 
+	xhci_debugfs_exit(xhci);
+
 	spin_lock_irq(&xhci->lock);
 	xhci->xhc_state |= XHCI_STATE_HALTED;
 	xhci->cmd_ring_state = CMD_RING_STATE_STOPPED;
@@ -1600,6 +1606,8 @@ static int xhci_drop_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
 	ctrl_ctx->add_flags &= cpu_to_le32(~drop_flag);
 	new_add_flags = le32_to_cpu(ctrl_ctx->add_flags);
 
+	xhci_debugfs_remove_endpoint(xhci, xhci->devs[udev->slot_id], ep_index);
+
 	xhci_endpoint_zero(xhci, xhci->devs[udev->slot_id], ep);
 
 	if (xhci->quirks & XHCI_MTK_HOST)
@@ -1722,6 +1730,8 @@ static int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
 	/* Store the usb_device pointer for later use */
 	ep->hcpriv = udev;
 
+	xhci_debugfs_create_endpoint(xhci, virt_dev, ep_index);
+
 	xhci_dbg(xhci, "add ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x\n",
 			(unsigned int) ep->desc.bEndpointAddress,
 			udev->slot_id,
@@ -2772,6 +2782,7 @@ static void xhci_reset_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
 	/* Free any rings allocated for added endpoints */
 	for (i = 0; i < 31; i++) {
 		if (virt_dev->eps[i].new_ring) {
+			xhci_debugfs_remove_endpoint(xhci, virt_dev, i);
 			xhci_ring_free(xhci, virt_dev->eps[i].new_ring);
 			virt_dev->eps[i].new_ring = NULL;
 		}
@@ -3487,6 +3498,7 @@ static int xhci_discover_or_reset_device(struct usb_hcd *hcd,
 		}
 
 		if (ep->ring) {
+			xhci_debugfs_remove_endpoint(xhci, virt_dev, i);
 			xhci_free_endpoint_ring(xhci, virt_dev, i);
 			last_freed_endpoint = i;
 		}
@@ -3521,6 +3533,8 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
 	int i, ret;
 	struct xhci_command *command;
 
+	xhci_debugfs_remove_slot(xhci, udev->slot_id);
+
 	command = xhci_alloc_command(xhci, false, false, GFP_KERNEL);
 	if (!command)
 		return;
@@ -3693,6 +3707,8 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
 
 	udev->slot_id = slot_id;
 
+	xhci_debugfs_create_slot(xhci, slot_id);
+
 #ifndef CONFIG_USB_DEFAULT_PERSIST
 	/*
 	 * If resetting upon resume, we can't put the controller into runtime
@@ -5003,6 +5019,8 @@ static int __init xhci_hcd_init(void)
 	if (usb_disabled())
 		return -ENODEV;
 
+	xhci_debugfs_create_root();
+
 	return 0;
 }
 
@@ -5010,7 +5028,10 @@ static int __init xhci_hcd_init(void)
  * If an init function is provided, an exit function must also be provided
  * to allow module unload.
  */
-static void __exit xhci_hcd_fini(void) { }
+static void __exit xhci_hcd_fini(void)
+{
+	xhci_debugfs_remove_root();
+}
 
 module_init(xhci_hcd_init);
 module_exit(xhci_hcd_fini);

drivers/usb/host/xhci.h

@@ -131,6 +131,8 @@ struct xhci_cap_regs {
 /* Extended Capabilities pointer from PCI base - section 5.3.6 */
 #define HCC_EXT_CAPS(p)		XHCI_HCC_EXT_CAPS(p)
 
+#define CTX_SIZE(_hcc)		(HCC_64BYTE_CONTEXT(_hcc) ? 64 : 32)
+
 /* db_off bitmask - bits 0:1 reserved */
 #define	DBOFF_MASK	(~0x3)
 
@@ -1005,6 +1007,8 @@ struct xhci_virt_device {
 	struct xhci_tt_bw_info		*tt_info;
 	/* The current max exit latency for the enabled USB3 link states. */
 	u16				current_mel;
+	/* Used for the debugfs interfaces. */
+	void				*debugfs_private;
 };
 
 /*
@@ -1858,6 +1862,10 @@ struct xhci_hcd {
 /* Compliance Mode Timer Triggered every 2 seconds */
 #define COMP_MODE_RCVRY_MSECS 2000
 
+	struct dentry		*debugfs_root;
+	struct dentry		*debugfs_slots;
+	struct list_head	regset_list;
+
 	/* platform-specific data -- must come last */
 	unsigned long		priv[0] __aligned(sizeof(s64));
 };
@@ -2106,6 +2114,7 @@ struct xhci_ep_ctx *xhci_get_ep_ctx(struct xhci_hcd *xhci, struct xhci_container
 struct xhci_ring *xhci_triad_to_transfer_ring(struct xhci_hcd *xhci,
 		unsigned int slot_id, unsigned int ep_index,
 		unsigned int stream_id);
+
 static inline struct xhci_ring *xhci_urb_to_transfer_ring(struct xhci_hcd *xhci,
 								struct urb *urb)
 {