path: root/drivers/thunderbolt/debugfs.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Debugfs interface
 *
 * Copyright (C) 2020, Intel Corporation
 * Authors: Gil Fine <gil.fine@intel.com>
 *	    Mika Westerberg <mika.westerberg@linux.intel.com>
 */

#include <linux/debugfs.h>
#include <linux/pm_runtime.h>
#include <linux/uaccess.h>

#include "tb.h"
#include "sb_regs.h"

#define PORT_CAP_V1_PCIE_LEN	1
#define PORT_CAP_V2_PCIE_LEN	2
#define PORT_CAP_POWER_LEN	2
#define PORT_CAP_LANE_LEN	3
#define PORT_CAP_USB3_LEN	5
#define PORT_CAP_DP_V1_LEN	9
#define PORT_CAP_DP_V2_LEN	14
#define PORT_CAP_TMU_V1_LEN	8
#define PORT_CAP_TMU_V2_LEN	10
#define PORT_CAP_BASIC_LEN	9
#define PORT_CAP_USB4_LEN	20

#define SWITCH_CAP_TMU_LEN	26
#define SWITCH_CAP_BASIC_LEN	27

#define PATH_LEN		2

#define COUNTER_SET_LEN		3

#define DEBUGFS_ATTR(__space, __write)					\
static int __space ## _open(struct inode *inode, struct file *file)	\
{									\
	return single_open(file, __space ## _show, inode->i_private);	\
}									\
									\
static const struct file_operations __space ## _fops = {		\
	.owner = THIS_MODULE,						\
	.open = __space ## _open,					\
	.release = single_release,					\
	.read  = seq_read,						\
	.write = __write,						\
	.llseek = seq_lseek,						\
}

#define DEBUGFS_ATTR_RO(__space)					\
	DEBUGFS_ATTR(__space, NULL)

#define DEBUGFS_ATTR_RW(__space)					\
	DEBUGFS_ATTR(__space, __space ## _write)

static struct dentry *tb_debugfs_root;

static void *validate_and_copy_from_user(const void __user *user_buf,
					 size_t *count)
{
	size_t nbytes;
	void *buf;

	if (!*count)
		return ERR_PTR(-EINVAL);

	if (!access_ok(user_buf, *count))
		return ERR_PTR(-EFAULT);

	buf = (void *)get_zeroed_page(GFP_KERNEL);
	if (!buf)
		return ERR_PTR(-ENOMEM);

	nbytes = min_t(size_t, *count, PAGE_SIZE);
	if (copy_from_user(buf, user_buf, nbytes)) {
		free_page((unsigned long)buf);
		return ERR_PTR(-EFAULT);
	}

	*count = nbytes;
	return buf;
}

static bool parse_line(char **line, u32 *offs, u32 *val, int short_fmt_len,
		       int long_fmt_len)
{
	char *token;
	u32 v[5];
	int ret;

	token = strsep(line, "\n");
	if (!token)
		return false;

	/*
	 * For Adapter/Router configuration space:
	 * Short format is: offset value\n
	 *		    v[0]   v[1]
	 * Long format as produced from the read side:
	 * offset relative_offset cap_id vs_cap_id value\n
	 * v[0]   v[1]            v[2]   v[3]      v[4]
	 *
	 * For Counter configuration space:
	 * Short format is: offset\n
	 *		    v[0]
	 * Long format as produced from the read side:
	 * offset relative_offset counter_id value\n
	 * v[0]   v[1]            v[2]       v[3]
	 */
	ret = sscanf(token, "%i %i %i %i %i", &v[0], &v[1], &v[2], &v[3], &v[4]);
	/* In case of Counters, clear counter, "val" content is NA */
	if (ret == short_fmt_len) {
		*offs = v[0];
		*val = v[short_fmt_len - 1];
		return true;
	} else if (ret == long_fmt_len) {
		*offs = v[0];
		*val = v[long_fmt_len - 1];
		return true;
	}

	return false;
}

#if IS_ENABLED(CONFIG_USB4_DEBUGFS_WRITE)
static ssize_t regs_write(struct tb_switch *sw, struct tb_port *port,
			  const char __user *user_buf, size_t count,
			  loff_t *ppos)
{
	struct tb *tb = sw->tb;
	char *line, *buf;
	u32 val, offset;
	int ret = 0;

	buf = validate_and_copy_from_user(user_buf, &count);
	if (IS_ERR(buf))
		return PTR_ERR(buf);

	pm_runtime_get_sync(&sw->dev);

	if (mutex_lock_interruptible(&tb->lock)) {
		ret = -ERESTARTSYS;
		goto out;
	}

	/* User did hardware changes behind the driver's back */
	add_taint(TAINT_USER, LOCKDEP_STILL_OK);

	line = buf;
	while (parse_line(&line, &offset, &val, 2, 5)) {
		if (port)
			ret = tb_port_write(port, &val, TB_CFG_PORT, offset, 1);
		else
			ret = tb_sw_write(sw, &val, TB_CFG_SWITCH, offset, 1);
		if (ret)
			break;
	}

	mutex_unlock(&tb->lock);

out:
	pm_runtime_mark_last_busy(&sw->dev);
	pm_runtime_put_autosuspend(&sw->dev);
	free_page((unsigned long)buf);

	return ret < 0 ? ret : count;
}

static ssize_t port_regs_write(struct file *file, const char __user *user_buf,
			       size_t count, loff_t *ppos)
{
	struct seq_file *s = file->private_data;
	struct tb_port *port = s->private;

	return regs_write(port->sw, port, user_buf, count, ppos);
}

static ssize_t switch_regs_write(struct file *file, const char __user *user_buf,
				 size_t count, loff_t *ppos)
{
	struct seq_file *s = file->private_data;
	struct tb_switch *sw = s->private;

	return regs_write(sw, NULL, user_buf, count, ppos);
}
#define DEBUGFS_MODE		0600
#else
#define port_regs_write		NULL
#define switch_regs_write	NULL
#define DEBUGFS_MODE		0400
#endif

#if IS_ENABLED(CONFIG_USB4_DEBUGFS_MARGINING)
/**
 * struct tb_margining - Lane margining support
 * @caps: Port lane margining capabilities
 * @results: Last lane margining results
 * @lanes: %0, %1 or %7 (all)
 * @min_ber_level: Minimum supported BER level contour value
 * @max_ber_level: Maximum supported BER level contour value
 * @ber_level: Current BER level contour value
 * @voltage_steps: Number of mandatory voltage steps
 * @max_voltage_offset: Maximum mandatory voltage offset (in mV)
 * @time_steps: Number of time margin steps
 * @max_time_offset: Maximum time margin offset (in mUI)
 * @software: %true if software margining is used instead of hardware
 * @time: %true if time margining is used instead of voltage
 * @right_high: %false if left/low margin test is performed, %true if
 *		right/high
 */
struct tb_margining {
	u32 caps[2];
	u32 results[2];
	unsigned int lanes;
	unsigned int min_ber_level;
	unsigned int max_ber_level;
	unsigned int ber_level;
	unsigned int voltage_steps;
	unsigned int max_voltage_offset;
	unsigned int time_steps;
	unsigned int max_time_offset;
	bool software;
	bool time;
	bool right_high;
};

static bool supports_software(const struct usb4_port *usb4)
{
	return usb4->margining->caps[0] & USB4_MARGIN_CAP_0_MODES_SW;
}

static bool supports_hardware(const struct usb4_port *usb4)
{
	return usb4->margining->caps[0] & USB4_MARGIN_CAP_0_MODES_HW;
}

static bool both_lanes(const struct usb4_port *usb4)
{
	return usb4->margining->caps[0] & USB4_MARGIN_CAP_0_2_LANES;
}

static unsigned int independent_voltage_margins(const struct usb4_port *usb4)
{
	return (usb4->margining->caps[0] & USB4_MARGIN_CAP_0_VOLTAGE_INDP_MASK) >>
		USB4_MARGIN_CAP_0_VOLTAGE_INDP_SHIFT;
}

static bool supports_time(const struct usb4_port *usb4)
{
	return usb4->margining->caps[0] & USB4_MARGIN_CAP_0_TIME;
}

/* Only applicable if supports_time() returns true */
static unsigned int independent_time_margins(const struct usb4_port *usb4)
{
	return (usb4->margining->caps[1] & USB4_MARGIN_CAP_1_TIME_INDP_MASK) >>
		USB4_MARGIN_CAP_1_TIME_INDP_SHIFT;
}

static ssize_t
margining_ber_level_write(struct file *file, const char __user *user_buf,
			   size_t count, loff_t *ppos)
{
	struct seq_file *s = file->private_data;
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;
	struct tb *tb = port->sw->tb;
	unsigned int val;
	int ret = 0;
	char *buf;

	if (mutex_lock_interruptible(&tb->lock))
		return -ERESTARTSYS;

	if (usb4->margining->software) {
		ret = -EINVAL;
		goto out_unlock;
	}

	buf = validate_and_copy_from_user(user_buf, &count);
	if (IS_ERR(buf)) {
		ret = PTR_ERR(buf);
		goto out_unlock;
	}

	buf[count - 1] = '\0';

	ret = kstrtouint(buf, 10, &val);
	if (ret)
		goto out_free;

	if (val < usb4->margining->min_ber_level ||
	    val > usb4->margining->max_ber_level) {
		ret = -EINVAL;
		goto out_free;
	}

	usb4->margining->ber_level = val;

out_free:
	free_page((unsigned long)buf);
out_unlock:
	mutex_unlock(&tb->lock);

	return ret < 0 ? ret : count;
}

static void ber_level_show(struct seq_file *s, unsigned int val)
{
	if (val % 2)
		seq_printf(s, "3 * 1e%d (%u)\n", -12 + (val + 1) / 2, val);
	else
		seq_printf(s, "1e%d (%u)\n", -12 + val / 2, val);
}

static int margining_ber_level_show(struct seq_file *s, void *not_used)
{
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;

	if (usb4->margining->software)
		return -EINVAL;
	ber_level_show(s, usb4->margining->ber_level);
	return 0;
}
DEBUGFS_ATTR_RW(margining_ber_level);

static int margining_caps_show(struct seq_file *s, void *not_used)
{
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;
	struct tb *tb = port->sw->tb;
	u32 cap0, cap1;

	if (mutex_lock_interruptible(&tb->lock))
		return -ERESTARTSYS;

	/* Dump the raw caps first */
	cap0 = usb4->margining->caps[0];
	seq_printf(s, "0x%08x\n", cap0);
	cap1 = usb4->margining->caps[1];
	seq_printf(s, "0x%08x\n", cap1);

	seq_printf(s, "# software margining: %s\n",
		   supports_software(usb4) ? "yes" : "no");
	if (supports_hardware(usb4)) {
		seq_puts(s, "# hardware margining: yes\n");
		seq_puts(s, "# minimum BER level contour: ");
		ber_level_show(s, usb4->margining->min_ber_level);
		seq_puts(s, "# maximum BER level contour: ");
		ber_level_show(s, usb4->margining->max_ber_level);
	} else {
		seq_puts(s, "# hardware margining: no\n");
	}

	seq_printf(s, "# both lanes simultaneously: %s\n",
		  both_lanes(usb4) ? "yes" : "no");
	seq_printf(s, "# voltage margin steps: %u\n",
		   usb4->margining->voltage_steps);
	seq_printf(s, "# maximum voltage offset: %u mV\n",
		   usb4->margining->max_voltage_offset);

	switch (independent_voltage_margins(usb4)) {
	case USB4_MARGIN_CAP_0_VOLTAGE_MIN:
		seq_puts(s, "# returns minimum between high and low voltage margins\n");
		break;
	case USB4_MARGIN_CAP_0_VOLTAGE_HL:
		seq_puts(s, "# returns high or low voltage margin\n");
		break;
	case USB4_MARGIN_CAP_0_VOLTAGE_BOTH:
		seq_puts(s, "# returns both high and low margins\n");
		break;
	}

	if (supports_time(usb4)) {
		seq_puts(s, "# time margining: yes\n");
		seq_printf(s, "# time margining is destructive: %s\n",
			   cap1 & USB4_MARGIN_CAP_1_TIME_DESTR ? "yes" : "no");

		switch (independent_time_margins(usb4)) {
		case USB4_MARGIN_CAP_1_TIME_MIN:
			seq_puts(s, "# returns minimum between left and right time margins\n");
			break;
		case USB4_MARGIN_CAP_1_TIME_LR:
			seq_puts(s, "# returns left or right margin\n");
			break;
		case USB4_MARGIN_CAP_1_TIME_BOTH:
			seq_puts(s, "# returns both left and right margins\n");
			break;
		}

		seq_printf(s, "# time margin steps: %u\n",
			   usb4->margining->time_steps);
		seq_printf(s, "# maximum time offset: %u mUI\n",
			   usb4->margining->max_time_offset);
	} else {
		seq_puts(s, "# time margining: no\n");
	}

	mutex_unlock(&tb->lock);
	return 0;
}
DEBUGFS_ATTR_RO(margining_caps);

static ssize_t
margining_lanes_write(struct file *file, const char __user *user_buf,
		      size_t count, loff_t *ppos)
{
	struct seq_file *s = file->private_data;
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;
	struct tb *tb = port->sw->tb;
	int ret = 0;
	char *buf;

	buf = validate_and_copy_from_user(user_buf, &count);
	if (IS_ERR(buf))
		return PTR_ERR(buf);

	buf[count - 1] = '\0';

	if (mutex_lock_interruptible(&tb->lock)) {
		ret = -ERESTARTSYS;
		goto out_free;
	}

	if (!strcmp(buf, "0")) {
		usb4->margining->lanes = 0;
	} else if (!strcmp(buf, "1")) {
		usb4->margining->lanes = 1;
	} else if (!strcmp(buf, "all")) {
		/* Needs to be supported */
		if (both_lanes(usb4))
			usb4->margining->lanes = 7;
		else
			ret = -EINVAL;
	} else {
		ret = -EINVAL;
	}

	mutex_unlock(&tb->lock);

out_free:
	free_page((unsigned long)buf);
	return ret < 0 ? ret : count;
}

static int margining_lanes_show(struct seq_file *s, void *not_used)
{
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;
	struct tb *tb = port->sw->tb;
	unsigned int lanes;

	if (mutex_lock_interruptible(&tb->lock))
		return -ERESTARTSYS;

	lanes = usb4->margining->lanes;
	if (both_lanes(usb4)) {
		if (!lanes)
			seq_puts(s, "[0] 1 all\n");
		else if (lanes == 1)
			seq_puts(s, "0 [1] all\n");
		else
			seq_puts(s, "0 1 [all]\n");
	} else {
		if (!lanes)
			seq_puts(s, "[0] 1\n");
		else
			seq_puts(s, "0 [1]\n");
	}

	mutex_unlock(&tb->lock);
	return 0;
}
DEBUGFS_ATTR_RW(margining_lanes);

static ssize_t margining_mode_write(struct file *file,
				   const char __user *user_buf,
				   size_t count, loff_t *ppos)
{
	struct seq_file *s = file->private_data;
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;
	struct tb *tb = port->sw->tb;
	int ret = 0;
	char *buf;

	buf = validate_and_copy_from_user(user_buf, &count);
	if (IS_ERR(buf))
		return PTR_ERR(buf);

	buf[count - 1] = '\0';

	if (mutex_lock_interruptible(&tb->lock)) {
		ret = -ERESTARTSYS;
		goto out_free;
	}

	if (!strcmp(buf, "software")) {
		if (supports_software(usb4))
			usb4->margining->software = true;
		else
			ret = -EINVAL;
	} else if (!strcmp(buf, "hardware")) {
		if (supports_hardware(usb4))
			usb4->margining->software = false;
		else
			ret = -EINVAL;
	} else {
		ret = -EINVAL;
	}

	mutex_unlock(&tb->lock);

out_free:
	free_page((unsigned long)buf);
	return ret ? ret : count;
}

static int margining_mode_show(struct seq_file *s, void *not_used)
{
	const struct tb_port *port = s->private;
	const struct usb4_port *usb4 = port->usb4;
	struct tb *tb = port->sw->tb;
	const char *space = "";

	if (mutex_lock_interruptible(&tb->lock))
		return -ERESTARTSYS;

	if (supports_software(usb4)) {
		if (usb4->margining->software)
			seq_puts(s, "[software]");
		else
			seq_puts(s, "software");
		space = " ";
	}
	if (supports_hardware(usb4)) {
		if (usb4->margining->software)
			seq_printf(s, "%shardware", space);
		else
			seq_printf(s, "%s[hardware]", space);
	}

	mutex_unlock(&tb->lock);

	seq_puts(s, "\n");
	return 0;
}
DEBUGFS_ATTR_RW(margining_mode);

static int margining_run_write(void *data, u64 val)
{
	struct tb_port *port = data;
	struct usb4_port *usb4 = port->usb4;
	struct tb_switch *sw = port->sw;
	struct tb_margining *margining;
	struct tb_switch *down_sw;
	struct tb *tb = sw->tb;
	int ret, clx;

	if (val != 1)
		return -EINVAL;

	pm_runtime_get_sync(&sw->dev);

	if (mutex_lock_interruptible(&tb->lock)) {
		ret = -ERESTARTSYS;
		goto out_rpm_put;
	}

	if (tb_is_upstream_port(port))
		down_sw = sw;
	else if (port->remote)
		down_sw = port->remote->sw;
	else
		down_sw = NULL;

	if (down_sw) {
		/*
		 * CL states may interfere with lane margining so
		 * disable them temporarily now.
		 */
		ret = tb_switch_clx_disable(down_sw);
		if (ret < 0) {
			tb_sw_warn(down_sw, "failed to disable CL states\n");
			goto out_unlock;
		}
		clx = ret;
	}

	margining = usb4->margining;

	if (margining->software) {
		tb_port_dbg(port, "running software %s lane margining for lanes %u\n",
			    margining->time ? "time" : "voltage", margining->lanes);
		ret = usb4_port_sw_margin(port, margining->lanes, margining->time,
					  margining->right_high,
					  USB4_MARGIN_SW_COUNTER_CLEAR);
		if (ret)
			goto out_clx;

		ret = usb4_port_sw_margin_errors(port, &margining->results[0]);
	} else {
		tb_port_dbg(port, "running hardware %s lane margining for lanes %u\n",
			    margining->time ? "time" : "voltage", margining->lanes);
		/* Clear the results */
		margining->results[0] = 0;
		margining->results[1] = 0;
		ret = usb4_port_hw_margin(port, margining->lanes,
					  margining->ber_level, margining->time,
					  margining->right_high, margining->results);
	}

out_clx:
	if (down_sw)
		tb_switch_clx_enable(down_sw, clx);
out_unlock:
	mutex_unlock(&tb->lock);
out_rpm_put:
	pm_runtime_mark_last_busy(&sw->dev);
	pm_runtime_put_autosuspend(&sw->dev);

	return ret;
}
DEFINE_DEBUGFS_ATTRIBUTE(margining_run_fops, NULL, margining_run_write,
			 "%llu\n");

static ssize_t margining_results_write(struct file *file,
				       const char __user *user_buf,
				       size_t count, loff_t *ppos)
{
	struct seq_file *s = file->private_data;
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;
	struct tb *tb = port->sw->tb;

	if (mutex_lock_interruptible(&tb->lock))
		return -ERESTARTSYS;

	/* Just clear the results */
	usb4->margining->results[0] = 0;
	usb4->margining->results[1] = 0;

	mutex_unlock(&tb->lock);
	return count;
}

static void voltage_margin_show(struct seq_file *s,
				const struct tb_margining *margining, u8 val)
{
	unsigned int tmp, voltage;

	tmp = val & USB4_MARGIN_HW_RES_1_MARGIN_MASK;
	voltage = tmp * margining->max_voltage_offset / margining->voltage_steps;
	seq_printf(s, "%u mV (%u)", voltage, tmp);
	if (val & USB4_MARGIN_HW_RES_1_EXCEEDS)
		seq_puts(s, " exceeds maximum");
	seq_puts(s, "\n");
}

static void time_margin_show(struct seq_file *s,
			     const struct tb_margining *margining, u8 val)
{
	unsigned int tmp, interval;

	tmp = val & USB4_MARGIN_HW_RES_1_MARGIN_MASK;
	interval = tmp * margining->max_time_offset / margining->time_steps;
	seq_printf(s, "%u mUI (%u)", interval, tmp);
	if (val & USB4_MARGIN_HW_RES_1_EXCEEDS)
		seq_puts(s, " exceeds maximum");
	seq_puts(s, "\n");
}

static int margining_results_show(struct seq_file *s, void *not_used)
{
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;
	struct tb_margining *margining;
	struct tb *tb = port->sw->tb;

	if (mutex_lock_interruptible(&tb->lock))
		return -ERESTARTSYS;

	margining = usb4->margining;
	/* Dump the raw results first */
	seq_printf(s, "0x%08x\n", margining->results[0]);
	/* Only the hardware margining has two result dwords */
	if (!margining->software) {
		unsigned int val;

		seq_printf(s, "0x%08x\n", margining->results[1]);

		if (margining->time) {
			if (!margining->lanes || margining->lanes == 7) {
				val = margining->results[1];
				seq_puts(s, "# lane 0 right time margin: ");
				time_margin_show(s, margining, val);
				val = margining->results[1] >>
					USB4_MARGIN_HW_RES_1_L0_LL_MARGIN_SHIFT;
				seq_puts(s, "# lane 0 left time margin: ");
				time_margin_show(s, margining, val);
			}
			if (margining->lanes == 1 || margining->lanes == 7) {
				val = margining->results[1] >>
					USB4_MARGIN_HW_RES_1_L1_RH_MARGIN_SHIFT;
				seq_puts(s, "# lane 1 right time margin: ");
				time_margin_show(s, margining, val);
				val = margining->results[1] >>
					USB4_MARGIN_HW_RES_1_L1_LL_MARGIN_SHIFT;
				seq_puts(s, "# lane 1 left time margin: ");
				time_margin_show(s, margining, val);
			}
		} else {
			if (!margining->lanes || margining->lanes == 7) {
				val = margining->results[1];
				seq_puts(s, "# lane 0 high voltage margin: ");
				voltage_margin_show(s, margining, val);
				val = margining->results[1] >>
					USB4_MARGIN_HW_RES_1_L0_LL_MARGIN_SHIFT;
				seq_puts(s, "# lane 0 low voltage margin: ");
				voltage_margin_show(s, margining, val);
			}
			if (margining->lanes == 1 || margining->lanes == 7) {
				val = margining->results[1] >>
					USB4_MARGIN_HW_RES_1_L1_RH_MARGIN_SHIFT;
				seq_puts(s, "# lane 1 high voltage margin: ");
				voltage_margin_show(s, margining, val);
				val = margining->results[1] >>
					USB4_MARGIN_HW_RES_1_L1_LL_MARGIN_SHIFT;
				seq_puts(s, "# lane 1 low voltage margin: ");
				voltage_margin_show(s, margining, val);
			}
		}
	}

	mutex_unlock(&tb->lock);
	return 0;
}
DEBUGFS_ATTR_RW(margining_results);

static ssize_t margining_test_write(struct file *file,
				    const char __user *user_buf,
				    size_t count, loff_t *ppos)
{
	struct seq_file *s = file->private_data;
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;
	struct tb *tb = port->sw->tb;
	int ret = 0;
	char *buf;

	buf = validate_and_copy_from_user(user_buf, &count);
	if (IS_ERR(buf))
		return PTR_ERR(buf);

	buf[count - 1] = '\0';

	if (mutex_lock_interruptible(&tb->lock)) {
		ret = -ERESTARTSYS;
		goto out_free;
	}

	if (!strcmp(buf, "time") && supports_time(usb4))
		usb4->margining->time = true;
	else if (!strcmp(buf, "voltage"))
		usb4->margining->time = false;
	else
		ret = -EINVAL;

	mutex_unlock(&tb->lock);

out_free:
	free_page((unsigned long)buf);
	return ret ? ret : count;
}

static int margining_test_show(struct seq_file *s, void *not_used)
{
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;
	struct tb *tb = port->sw->tb;

	if (mutex_lock_interruptible(&tb->lock))
		return -ERESTARTSYS;

	if (supports_time(usb4)) {
		if (usb4->margining->time)
			seq_puts(s, "voltage [time]\n");
		else
			seq_puts(s, "[voltage] time\n");
	} else {
		seq_puts(s, "[voltage]\n");
	}

	mutex_unlock(&tb->lock);
	return 0;
}
DEBUGFS_ATTR_RW(margining_test);

static ssize_t margining_margin_write(struct file *file,
				    const char __user *user_buf,
				    size_t count, loff_t *ppos)
{
	struct seq_file *s = file->private_data;
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;
	struct tb *tb = port->sw->tb;
	int ret = 0;
	char *buf;

	buf = validate_and_copy_from_user(user_buf, &count);
	if (IS_ERR(buf))
		return PTR_ERR(buf);

	buf[count - 1] = '\0';

	if (mutex_lock_interruptible(&tb->lock)) {
		ret = -ERESTARTSYS;
		goto out_free;
	}

	if (usb4->margining->time) {
		if (!strcmp(buf, "left"))
			usb4->margining->right_high = false;
		else if (!strcmp(buf, "right"))
			usb4->margining->right_high = true;
		else
			ret = -EINVAL;
	} else {
		if (!strcmp(buf, "low"))
			usb4->margining->right_high = false;
		else if (!strcmp(buf, "high"))
			usb4->margining->right_high = true;
		else
			ret = -EINVAL;
	}

	mutex_unlock(&tb->lock);

out_free:
	free_page((unsigned long)buf);
	return ret ? ret : count;
}

static int margining_margin_show(struct seq_file *s, void *not_used)
{
	struct tb_port *port = s->private;
	struct usb4_port *usb4 = port->usb4;
	struct tb *tb = port->sw->tb;

	if (mutex_lock_interruptible(&tb->lock))
		return -ERESTARTSYS;

	if (usb4->margining->time) {
		if (usb4->margining->right_high)
			seq_puts(s, "left [right]\n");
		else
			seq_puts(s, "[left] right\n");
	} else {
		if (usb4->margining->right_high)
			seq_puts(s, "low [high]\n");
		else
			seq_puts(s, "[low] high\n");
	}

	mutex_unlock(&tb->lock);
	return 0;
}
DEBUGFS_ATTR_RW(margining_margin);

static void margining_port_init(struct tb_port *port)
{
	struct tb_margining *margining;
	struct dentry *dir, *parent;
	struct usb4_port *usb4;
	char dir_name[10];
	unsigned int val;
	int ret;

	usb4 = port->usb4;
	if (!usb4)
		return;

	snprintf(dir_name, sizeof(dir_name), "port%d", port->port);
	parent = debugfs_lookup(dir_name, port->sw->debugfs_dir);

	margining = kzalloc(sizeof(*margining), GFP_KERNEL);
	if (!margining)
		return;

	ret = usb4_port_margining_caps(port, margining->caps);
	if (ret) {
		kfree(margining);
		return;
	}

	usb4->margining = margining;

	/* Set the initial mode */
	if (supports_software(usb4))
		margining->software = true;

	val = (margining->caps[0] & USB4_MARGIN_CAP_0_VOLTAGE_STEPS_MASK) >>
		USB4_MARGIN_CAP_0_VOLTAGE_STEPS_SHIFT;
	margining->voltage_steps = val;
	val = (margining->caps[0] & USB4_MARGIN_CAP_0_MAX_VOLTAGE_OFFSET_MASK) >>
		USB4_MARGIN_CAP_0_MAX_VOLTAGE_OFFSET_SHIFT;
	margining->max_voltage_offset = 74 + val * 2;

	if (supports_time(usb4)) {
		val = (margining->caps[1] & USB4_MARGIN_CAP_1_TIME_STEPS_MASK) >>
			USB4_MARGIN_CAP_1_TIME_STEPS_SHIFT;
		margining->time_steps = val;
		val = (margining->caps[1] & USB4_MARGIN_CAP_1_TIME_OFFSET_MASK) >>
			USB4_MARGIN_CAP_1_TIME_OFFSET_SHIFT;
		/*
		 * Store it as mUI (milli Unit Interval) because we want
		 * to keep it as integer.
		 */
		margining->max_time_offset = 200 + 10 * val;
	}

	dir = debugfs_create_dir("margining", parent);
	if (supports_hardware(usb4)) {
		val = (margining->caps[1] & USB4_MARGIN_CAP_1_MIN_BER_MASK) >>
			USB4_MARGIN_CAP_1_MIN_BER_SHIFT;
		margining->min_ber_level = val;
		val = (margining->caps[1] & USB4_MARGIN_CAP_1_MAX_BER_MASK) >>
			USB4_MARGIN_CAP_1_MAX_BER_SHIFT;
		margining->max_ber_level = val;

		/* Set the default to minimum */
		margining->ber_level = margining->min_ber_level;

		debugfs_create_file("ber_level_contour", 0400, dir, port,
				    &margining_ber_level_fops);
	}
	debugfs_create_file("caps", 0400, dir, port, &margining_caps_fops);
	debugfs_create_file("lanes", 0600, dir, port, &margining_lanes_fops);
	debugfs_create_file("mode", 0600, dir, port, &margining_mode_fops);
	debugfs_create_file("run", 0600, dir, port, &margining_run_fops);
	debugfs_create_file("results", 0600, dir, port, &margining_results_fops);
	debugfs_create_file("test", 0600, dir, port, &margining_test_fops);
	if (independent_voltage_margins(usb4) ||
	    (supports_time(usb4) && independent_time_margins(usb4)))
		debugfs_create_file("margin", 0600, dir, port, &margining_margin_fops);
}

static void margining_port_remove(struct tb_port *port)
{
	struct dentry *parent;
	char dir_name[10];

	if (!port->usb4)
		return;

	snprintf(dir_name, sizeof(dir_name), "port%d", port->port);
	parent = debugfs_lookup(dir_name, port->sw->debugfs_dir);
	if (parent)
		debugfs_lookup_and_remove("margining", parent);

	kfree(port->usb4->margining);
	port->usb4->margining = NULL;
}

static void margining_switch_init(struct tb_switch *sw)
{
	struct tb_port *upstream, *downstream;
	struct tb_switch *parent_sw;
	u64 route = tb_route(sw);

	if (!route)
		return;

	upstream = tb_upstream_port(sw);
	parent_sw = tb_switch_parent(sw);
	downstream = tb_port_at(route, parent_sw);

	margining_port_init(downstream);
	margining_port_init(upstream);
}

static void margining_switch_remove(struct tb_switch *sw)
{
	struct tb_port *upstream, *downstream;
	struct tb_switch *parent_sw;
	u64 route = tb_route(sw);

	if (!route)
		return;

	upstream = tb_upstream_port(sw);
	parent_sw = tb_switch_parent(sw);
	downstream = tb_port_at(route, parent_sw);

	margining_port_remove(upstream);
	margining_port_remove(downstream);
}

static void margining_xdomain_init(struct tb_xdomain *xd)
{
	struct tb_switch *parent_sw;
	struct tb_port *downstream;

	parent_sw = tb_xdomain_parent(xd);
	downstream = tb_port_at(xd->route, parent_sw);

	margining_port_init(downstream);
}

static void margining_xdomain_remove(struct tb_xdomain *xd)
{
	struct tb_switch *parent_sw;
	struct tb_port *downstream;

	parent_sw = tb_xdomain_parent(xd);
	downstream = tb_port_at(xd->route, parent_sw);
	margining_port_remove(downstream);
}
#else
static inline void margining_switch_init(struct tb_switch *sw) { }
static inline void margining_switch_remove(struct tb_switch *sw) { }
static inline void margining_xdomain_init(struct tb_xdomain *xd) { }
static inline void margining_xdomain_remove(struct tb_xdomain *xd) { }
#endif

static int port_clear_all_counters(struct tb_port *port)
{
	u32 *buf;
	int ret;

	buf = kcalloc(COUNTER_SET_LEN * port->config.max_counters, sizeof(u32),
		      GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	ret = tb_port_write(port, buf, TB_CFG_COUNTERS, 0,
			    COUNTER_SET_LEN * port->config.max_counters);
	kfree(buf);

	return ret;
}

static ssize_t counters_write(struct file *file, const char __user *user_buf,
			      size_t count, loff_t *ppos)
{
	struct seq_file *s = file->private_data;
	struct tb_port *port = s->private;
	struct tb_switch *sw = port->sw;
	struct tb *tb = port->sw->tb;
	char *buf;
	int ret;

	buf = validate_and_copy_from_user(user_buf, &count);
	if (IS_ERR(buf))
		return PTR_ERR(buf);

	pm_runtime_get_sync(&sw->dev);

	if (mutex_lock_interruptible(&tb->lock)) {
		ret = -ERESTARTSYS;
		goto out;
	}

	/* If written delimiter only, clear all counters in one shot */
	if (buf[0] == '\n') {
		ret = port_clear_all_counters(port);
	} else  {
		char *line = buf;
		u32 val, offset;

		ret = -EINVAL;
		while (parse_line(&line, &offset, &val, 1, 4)) {
			ret = tb_port_write(port, &val, TB_CFG_COUNTERS,
					    offset, 1);
			if (ret)
				break;
		}
	}

	mutex_unlock(&tb->lock);

out:
	pm_runtime_mark_last_busy(&sw->dev);
	pm_runtime_put_autosuspend(&sw->dev);
	free_page((unsigned long)buf);

	return ret < 0 ? ret : count;
}

static void cap_show_by_dw(struct seq_file *s, struct tb_switch *sw,
			   struct tb_port *port, unsigned int cap,
			   unsigned int offset, u8 cap_id, u8 vsec_id,
			   int dwords)
{
	int i, ret;
	u32 data;

	for (i = 0; i < dwords; i++) {
		if (port)
			ret = tb_port_read(port, &data, TB_CFG_PORT, cap + offset + i, 1);
		else
			ret = tb_sw_read(sw, &data, TB_CFG_SWITCH, cap + offset + i, 1);
		if (ret) {
			seq_printf(s, "0x%04x <not accessible>\n", cap + offset + i);
			continue;
		}

		seq_printf(s, "0x%04x %4d 0x%02x 0x%02x 0x%08x\n", cap + offset + i,
			   offset + i, cap_id, vsec_id, data);
	}
}

static void cap_show(struct seq_file *s, struct tb_switch *sw,
		     struct tb_port *port, unsigned int cap, u8 cap_id,
		     u8 vsec_id, int length)
{
	int ret, offset = 0;

	while (length > 0) {
		int i, dwords = min(length, TB_MAX_CONFIG_RW_LENGTH);
		u32 data[TB_MAX_CONFIG_RW_LENGTH];

		if (port)
			ret = tb_port_read(port, data, TB_CFG_PORT, cap + offset,
					   dwords);
		else
			ret = tb_sw_read(sw, data, TB_CFG_SWITCH, cap + offset, dwords);
		if (ret) {
			cap_show_by_dw(s, sw, port, cap, offset, cap_id, vsec_id, length);
			return;
		}

		for (i = 0; i < dwords; i++) {
			seq_printf(s, "0x%04x %4d 0x%02x 0x%02x 0x%08x\n",
				   cap + offset + i, offset + i,
				   cap_id, vsec_id, data[i]);
		}

		length -= dwords;
		offset += dwords;
	}
}

static void port_cap_show(struct tb_port *port, struct seq_file *s,
			  unsigned int cap)
{
	struct tb_cap_any header;
	u8 vsec_id = 0;
	size_t length;
	int ret;

	ret = tb_port_read(port, &header, TB_CFG_PORT, cap, 1);
	if (ret) {
		seq_printf(s, "0x%04x <capability read failed>\n", cap);
		return;
	}

	switch (header.basic.cap) {
	case TB_PORT_CAP_PHY:
		length = PORT_CAP_LANE_LEN;
		break;

	case TB_PORT_CAP_TIME1:
		if (usb4_switch_version(port->sw) < 2)
			length = PORT_CAP_TMU_V1_LEN;
		else
			length = PORT_CAP_TMU_V2_LEN;
		break;

	case TB_PORT_CAP_POWER:
		length = PORT_CAP_POWER_LEN;
		break;

	case TB_PORT_CAP_ADAP:
		if (tb_port_is_pcie_down(port) || tb_port_is_pcie_up(port)) {
			if (usb4_switch_version(port->sw) < 2)
				length = PORT_CAP_V1_PCIE_LEN;
			else
				length = PORT_CAP_V2_PCIE_LEN;
		} else if (tb_port_is_dpin(port)) {
			if (usb4_switch_version(port->sw) < 2)
				length = PORT_CAP_DP_V1_LEN;
			else
				length = PORT_CAP_DP_V2_LEN;
		} else if (tb_port_is_dpout(port)) {
			length = PORT_CAP_DP_V1_LEN;
		} else if (tb_port_is_usb3_down(port) ||
			   tb_port_is_usb3_up(port)) {
			length = PORT_CAP_USB3_LEN;
		} else {
			seq_printf(s, "0x%04x <unsupported capability 0x%02x>\n",
				   cap, header.basic.cap);
			return;
		}
		break;

	case TB_PORT_CAP_VSE:
		if (!header.extended_short.length) {
			ret = tb_port_read(port, (u32 *)&header + 1, TB_CFG_PORT,
					   cap + 1, 1);
			if (ret) {
				seq_printf(s, "0x%04x <capability read failed>\n",
					   cap + 1);
				return;
			}
			length = header.extended_long.length;
			vsec_id = header.extended_short.vsec_id;
		} else {
			length = header.extended_short.length;
			vsec_id = header.extended_short.vsec_id;
		}
		break;

	case TB_PORT_CAP_USB4:
		length = PORT_CAP_USB4_LEN;
		break;

	default:
		seq_printf(s, "0x%04x <unsupported capability 0x%02x>\n",
			   cap, header.basic.cap);
		return;
	}

	cap_show(s, NULL, port, cap, header.basic.cap, vsec_id, length);
}

static void port_caps_show(struct tb_port *port, struct seq_file *s)
{
	int cap;

	cap = tb_port_next_cap(port, 0);
	while (cap > 0) {
		port_cap_show(port, s, cap);
		cap = tb_port_next_cap(port, cap);
	}
}

static int port_basic_regs_show(struct tb_port *port, struct seq_file *s)
{
	u32 data[PORT_CAP_BASIC_LEN];
	int ret, i;

	ret = tb_port_read(port, data, TB_CFG_PORT, 0, ARRAY_SIZE(data));
	if (ret)
		return ret;

	for (i = 0; i < ARRAY_SIZE(data); i++)
		seq_printf(s, "0x%04x %4d 0x00 0x00 0x%08x\n", i, i, data[i]);

	return 0;
}

static int port_regs_show(struct seq_file *s, void *not_used)
{
	struct tb_port *port = s->private;
	struct tb_switch *sw = port->sw;
	struct tb *tb = sw->tb;
	int ret;

	pm_runtime_get_sync(&sw->dev);

	if (mutex_lock_interruptible(&tb->lock)) {
		ret = -ERESTARTSYS;
		goto out_rpm_put;
	}

	seq_puts(s, "# offset relative_offset cap_id vs_cap_id value\n");

	ret = port_basic_regs_show(port, s);
	if (ret)
		goto out_unlock;

	port_caps_show(port, s);

out_unlock:
	mutex_unlock(&tb->lock);
out_rpm_put:
	pm_runtime_mark_last_busy(&sw->dev);
	pm_runtime_put_autosuspend(&sw->dev);

	return ret;
}
DEBUGFS_ATTR_RW(port_regs);

static void switch_cap_show(struct tb_switch *sw, struct seq_file *s,
			    unsigned int cap)
{
	struct tb_cap_any header;
	int ret, length;
	u8 vsec_id = 0;

	ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, cap, 1);
	if (ret) {
		seq_printf(s, "0x%04x <capability read failed>\n", cap);
		return;
	}

	if (header.basic.cap == TB_SWITCH_CAP_VSE) {
		if (!header.extended_short.length) {
			ret = tb_sw_read(sw, (u32 *)&header + 1, TB_CFG_SWITCH,
					 cap + 1, 1);
			if (ret) {
				seq_printf(s, "0x%04x <capability read failed>\n",
					   cap + 1);
				return;
			}
			length = header.extended_long.length;
		} else {
			length = header.extended_short.length;
		}
		vsec_id = header.extended_short.vsec_id;
	} else {
		if (header.basic.cap == TB_SWITCH_CAP_TMU) {
			length = SWITCH_CAP_TMU_LEN;
		} else  {
			seq_printf(s, "0x%04x <unknown capability 0x%02x>\n",
				   cap, header.basic.cap);
			return;
		}
	}

	cap_show(s, sw, NULL, cap, header.basic.cap, vsec_id, length);
}

static void switch_caps_show(struct tb_switch *sw, struct seq_file *s)
{
	int cap;

	cap = tb_switch_next_cap(sw, 0);
	while (cap > 0) {
		switch_cap_show(sw, s, cap);
		cap = tb_switch_next_cap(sw, cap);
	}
}

static int switch_basic_regs_show(struct tb_switch *sw, struct seq_file *s)
{
	u32 data[SWITCH_CAP_BASIC_LEN];
	size_t dwords;
	int ret, i;

	/* Only USB4 has the additional registers */
	if (tb_switch_is_usb4(sw))
		dwords = ARRAY_SIZE(data);
	else
		dwords = 7;

	ret = tb_sw_read(sw, data, TB_CFG_SWITCH, 0, dwords);
	if (ret)
		return ret;

	for (i = 0; i < dwords; i++)
		seq_printf(s, "0x%04x %4d 0x00 0x00 0x%08x\n", i, i, data[i]);

	return 0;
}

static int switch_regs_show(struct seq_file *s, void *not_used)
{
	struct tb_switch *sw = s->private;
	struct tb *tb = sw->tb;
	int ret;

	pm_runtime_get_sync(&sw->dev);

	if (mutex_lock_interruptible(&tb->lock)) {
		ret = -ERESTARTSYS;
		goto out_rpm_put;
	}

	seq_puts(s, "# offset relative_offset cap_id vs_cap_id value\n");

	ret = switch_basic_regs_show(sw, s);
	if (ret)
		goto out_unlock;

	switch_caps_show(sw, s);

out_unlock:
	mutex_unlock(&tb->lock);
out_rpm_put:
	pm_runtime_mark_last_busy(&sw->dev);
	pm_runtime_put_autosuspend(&sw->dev);

	return ret;
}
DEBUGFS_ATTR_RW(switch_regs);

static int path_show_one(struct tb_port *port, struct seq_file *s, int hopid)
{
	u32 data[PATH_LEN];
	int ret, i;

	ret = tb_port_read(port, data, TB_CFG_HOPS, hopid * PATH_LEN,
			   ARRAY_SIZE(data));
	if (ret) {
		seq_printf(s, "0x%04x <not accessible>\n", hopid * PATH_LEN);
		return ret;
	}

	for (i = 0; i < ARRAY_SIZE(data); i++) {
		seq_printf(s, "0x%04x %4d 0x%02x 0x%08x\n",
			   hopid * PATH_LEN + i, i, hopid, data[i]);
	}

	return 0;
}

static int path_show(struct seq_file *s, void *not_used)
{
	struct tb_port *port = s->private;
	struct tb_switch *sw = port->sw;
	struct tb *tb = sw->tb;
	int start, i, ret = 0;

	pm_runtime_get_sync(&sw->dev);

	if (mutex_lock_interruptible(&tb->lock)) {
		ret = -ERESTARTSYS;
		goto out_rpm_put;
	}

	seq_puts(s, "# offset relative_offset in_hop_id value\n");

	/* NHI and lane adapters have entry for path 0 */
	if (tb_port_is_null(port) || tb_port_is_nhi(port)) {
		ret = path_show_one(port, s, 0);
		if (ret)
			goto out_unlock;
	}

	start = tb_port_is_nhi(port) ? 1 : TB_PATH_MIN_HOPID;

	for (i = start; i <= port->config.max_in_hop_id; i++) {
		ret = path_show_one(port, s, i);
		if (ret)
			break;
	}

out_unlock:
	mutex_unlock(&tb->lock);
out_rpm_put:
	pm_runtime_mark_last_busy(&sw->dev);
	pm_runtime_put_autosuspend(&sw->dev);

	return ret;
}
DEBUGFS_ATTR_RO(path);

static int counter_set_regs_show(struct tb_port *port, struct seq_file *s,
				 int counter)
{
	u32 data[COUNTER_SET_LEN];
	int ret, i;

	ret = tb_port_read(port, data, TB_CFG_COUNTERS,
			   counter * COUNTER_SET_LEN, ARRAY_SIZE(data));
	if (ret) {
		seq_printf(s, "0x%04x <not accessible>\n",
			   counter * COUNTER_SET_LEN);
		return ret;
	}

	for (i = 0; i < ARRAY_SIZE(data); i++) {
		seq_printf(s, "0x%04x %4d 0x%02x 0x%08x\n",
			   counter * COUNTER_SET_LEN + i, i, counter, data[i]);
	}

	return 0;
}

static int counters_show(struct seq_file *s, void *not_used)
{
	struct tb_port *port = s->private;
	struct tb_switch *sw = port->sw;
	struct tb *tb = sw->tb;
	int i, ret = 0;

	pm_runtime_get_sync(&sw->dev);

	if (mutex_lock_interruptible(&tb->lock)) {
		ret = -ERESTARTSYS;
		goto out;
	}

	seq_puts(s, "# offset relative_offset counter_id value\n");

	for (i = 0; i < port->config.max_counters; i++) {
		ret = counter_set_regs_show(port, s, i);
		if (ret)
			break;
	}

	mutex_unlock(&tb->lock);

out:
	pm_runtime_mark_last_busy(&sw->dev);
	pm_runtime_put_autosuspend(&sw->dev);

	return ret;
}
DEBUGFS_ATTR_RW(counters);

/**
 * tb_switch_debugfs_init() - Add debugfs entries for router
 * @sw: Pointer to the router
 *
 * Adds debugfs directories and files for given router.
 */
void tb_switch_debugfs_init(struct tb_switch *sw)
{
	struct dentry *debugfs_dir;
	struct tb_port *port;

	debugfs_dir = debugfs_create_dir(dev_name(&sw->dev), tb_debugfs_root);
	sw->debugfs_dir = debugfs_dir;
	debugfs_create_file("regs", DEBUGFS_MODE, debugfs_dir, sw,
			    &switch_regs_fops);

	tb_switch_for_each_port(sw, port) {
		struct dentry *debugfs_dir;
		char dir_name[10];

		if (port->disabled)
			continue;
		if (port->config.type == TB_TYPE_INACTIVE)
			continue;

		snprintf(dir_name, sizeof(dir_name), "port%d", port->port);
		debugfs_dir = debugfs_create_dir(dir_name, sw->debugfs_dir);
		debugfs_create_file("regs", DEBUGFS_MODE, debugfs_dir,
				    port, &port_regs_fops);
		debugfs_create_file("path", 0400, debugfs_dir, port,
				    &path_fops);
		if (port->config.counters_support)
			debugfs_create_file("counters", 0600, debugfs_dir, port,
					    &counters_fops);
	}

	margining_switch_init(sw);
}

/**
 * tb_switch_debugfs_remove() - Remove all router debugfs entries
 * @sw: Pointer to the router
 *
 * Removes all previously added debugfs entries under this router.
 */
void tb_switch_debugfs_remove(struct tb_switch *sw)
{
	margining_switch_remove(sw);
	debugfs_remove_recursive(sw->debugfs_dir);
}

void tb_xdomain_debugfs_init(struct tb_xdomain *xd)
{
	margining_xdomain_init(xd);
}

void tb_xdomain_debugfs_remove(struct tb_xdomain *xd)
{
	margining_xdomain_remove(xd);
}

/**
 * tb_service_debugfs_init() - Add debugfs directory for service
 * @svc: Thunderbolt service pointer
 *
 * Adds debugfs directory for service.
 */
void tb_service_debugfs_init(struct tb_service *svc)
{
	svc->debugfs_dir = debugfs_create_dir(dev_name(&svc->dev),
					      tb_debugfs_root);
}

/**
 * tb_service_debugfs_remove() - Remove service debugfs directory
 * @svc: Thunderbolt service pointer
 *
 * Removes the previously created debugfs directory for @svc.
 */
void tb_service_debugfs_remove(struct tb_service *svc)
{
	debugfs_remove_recursive(svc->debugfs_dir);
	svc->debugfs_dir = NULL;
}

void tb_debugfs_init(void)
{
	tb_debugfs_root = debugfs_create_dir("thunderbolt", NULL);
}

void tb_debugfs_exit(void)
{
	debugfs_remove_recursive(tb_debugfs_root);
}