arch/arm/mach-tegra/clock.c - kernel/tegra - Git at Google

 /*
  *
  * Copyright (C) 2010 Google, Inc.
  *
  * Author:
  *	Colin Cross <ccross@google.com>
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
  * may be copied, distributed, and modified under those terms.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  */

 #include <linux/kernel.h>
 #include <linux/clk.h>
 #include <linux/list.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/debugfs.h>
 #include <linux/slab.h>
 #include <linux/seq_file.h>
 #include <asm/clkdev.h>

 #include "clock.h"

 static LIST_HEAD(clocks);

 static DEFINE_SPINLOCK(clock_lock);

 struct clk *tegra_get_clock_by_name(const char *name)
 {
 	struct clk *c;
 	struct clk *ret = NULL;
 	unsigned long flags;
 	spin_lock_irqsave(&clock_lock, flags);
 	list_for_each_entry(c, &clocks, node) {
 		if (strcmp(c->name, name) == 0) {
 			ret = c;
 			break;
 		}
 	}
 	spin_unlock_irqrestore(&clock_lock, flags);
 	return ret;
 }

 int clk_reparent(struct clk *c, struct clk *parent)
 {
 	pr_debug("%s: %s\n", __func__, c->name);
 	if (c->refcnt && c->parent)
 		clk_disable_locked(c->parent);
 	c->parent = parent;
 	if (c->refcnt && c->parent)
 		clk_enable_locked(c->parent);
 	list_del(&c->sibling);
 	list_add_tail(&c->sibling, &parent->children);
 	return 0;
 }

 static void propagate_rate(struct clk *c)
 {
 	struct clk *clkp;
 	pr_debug("%s: %s\n", __func__, c->name);
 	list_for_each_entry(clkp, &c->children, sibling) {
 		pr_debug("   %s\n", clkp->name);
 		if (clkp->ops->recalculate_rate)
 			clkp->ops->recalculate_rate(clkp);
 		propagate_rate(clkp);
 	}
 }

 void clk_init(struct clk *c)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&clock_lock, flags);

 	INIT_LIST_HEAD(&c->children);
 	INIT_LIST_HEAD(&c->sibling);

 	if (c->ops && c->ops->init)
 		c->ops->init(c);

 	list_add(&c->node, &clocks);

 	if (c->parent)
 		list_add_tail(&c->sibling, &c->parent->children);

 	spin_unlock_irqrestore(&clock_lock, flags);
 }

 int clk_enable_locked(struct clk *c)
 {
 	int ret;
 	pr_debug("%s: %s\n", __func__, c->name);
 	if (c->refcnt == 0) {
 		if (c->parent) {
 			ret = clk_enable_locked(c->parent);
 			if (ret)
 				return ret;
 		}

 		if (c->ops && c->ops->enable) {
 			ret = c->ops->enable(c);
 			if (ret) {
 				if (c->parent)
 					clk_disable_locked(c->parent);
 				return ret;
 			}
 			c->state = ON;
 #ifdef CONFIG_DEBUG_FS
 			c->set = 1;
 #endif
 		}
 	}
 	c->refcnt++;

 	return 0;
 }

 int clk_enable(struct clk *c)
 {
 	int ret;
 	unsigned long flags;
 	spin_lock_irqsave(&clock_lock, flags);
 	ret = clk_enable_locked(c);
 	spin_unlock_irqrestore(&clock_lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL(clk_enable);

 void clk_disable_locked(struct clk *c)
 {
 	pr_debug("%s: %s\n", __func__, c->name);
 	if (c->refcnt == 0) {
 		WARN(1, "Attempting to disable clock %s with refcnt 0", c->name);
 		return;
 	}
 	if (c->refcnt == 1) {
 		if (c->ops && c->ops->disable)
 			c->ops->disable(c);

 		if (c->parent)
 			clk_disable_locked(c->parent);

 		c->state = OFF;
 	}
 	c->refcnt--;
 }

 void clk_disable(struct clk *c)
 {
 	unsigned long flags;
 	spin_lock_irqsave(&clock_lock, flags);
 	clk_disable_locked(c);
 	spin_unlock_irqrestore(&clock_lock, flags);
 }
 EXPORT_SYMBOL(clk_disable);

 int clk_set_parent_locked(struct clk *c, struct clk *parent)
 {
 	int ret;

 	pr_debug("%s: %s\n", __func__, c->name);

 	if (!c->ops || !c->ops->set_parent)
 		return -ENOSYS;

 	ret = c->ops->set_parent(c, parent);

 	if (ret)
 		return ret;

 	propagate_rate(c);

 	return 0;
 }

 int clk_set_parent(struct clk *c, struct clk *parent)
 {
 	int ret;
 	unsigned long flags;
 	spin_lock_irqsave(&clock_lock, flags);
 	ret = clk_set_parent_locked(c, parent);
 	spin_unlock_irqrestore(&clock_lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL(clk_set_parent);

 struct clk *clk_get_parent(struct clk *c)
 {
 	return c->parent;
 }
 EXPORT_SYMBOL(clk_get_parent);

 int clk_set_rate(struct clk *c, unsigned long rate)
 {
 	int ret = 0;
 	unsigned long flags;

 	spin_lock_irqsave(&clock_lock, flags);

 	pr_debug("%s: %s\n", __func__, c->name);

 	if (c->ops && c->ops->set_rate)
 		ret = c->ops->set_rate(c, rate);
 	else
 		ret = -ENOSYS;

 	propagate_rate(c);

 	spin_unlock_irqrestore(&clock_lock, flags);

 	return ret;
 }
 EXPORT_SYMBOL(clk_set_rate);

 unsigned long clk_get_rate(struct clk *c)
 {
 	unsigned long flags;
 	unsigned long ret;

 	spin_lock_irqsave(&clock_lock, flags);

 	pr_debug("%s: %s\n", __func__, c->name);

 	ret = c->rate;

 	spin_unlock_irqrestore(&clock_lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL(clk_get_rate);

 static int tegra_clk_init_one_from_table(struct tegra_clk_init_table *table)
 {
 	struct clk *c;
 	struct clk *p;

 	int ret = 0;

 	c = tegra_get_clock_by_name(table->name);

 	if (!c) {
 		pr_warning("Unable to initialize clock %s\n",
 			table->name);
 		return -ENODEV;
 	}

 	if (table->parent) {
 		p = tegra_get_clock_by_name(table->parent);
 		if (!p) {
 			pr_warning("Unable to find parent %s of clock %s\n",
 				table->parent, table->name);
 			return -ENODEV;
 		}

 		if (c->parent != p) {
 			ret = clk_set_parent(c, p);
 			if (ret) {
 				pr_warning("Unable to set parent %s of clock %s: %d\n",
 					table->parent, table->name, ret);
 				return -EINVAL;
 			}
 		}
 	}

 	if (table->rate && table->rate != clk_get_rate(c)) {
 		ret = clk_set_rate(c, table->rate);
 		if (ret) {
 			pr_warning("Unable to set clock %s to rate %lu: %d\n",
 				table->name, table->rate, ret);
 			return -EINVAL;
 		}
 	}

 	if (table->enabled) {
 		ret = clk_enable(c);
 		if (ret) {
 			pr_warning("Unable to enable clock %s: %d\n",
 				table->name, ret);
 			return -EINVAL;
 		}
 	}

 	return 0;
 }

 void tegra_clk_init_from_table(struct tegra_clk_init_table *table)
 {
 	for (; table->name; table++)
 		tegra_clk_init_one_from_table(table);
 }
 EXPORT_SYMBOL(tegra_clk_init_from_table);

 void tegra_periph_reset_deassert(struct clk *c)
 {
 	tegra2_periph_reset_deassert(c);
 }
 EXPORT_SYMBOL(tegra_periph_reset_deassert);

 void tegra_periph_reset_assert(struct clk *c)
 {
 	tegra2_periph_reset_assert(c);
 }
 EXPORT_SYMBOL(tegra_periph_reset_assert);

 int __init tegra_init_clock(void)
 {
 	tegra2_init_clocks();

 	return 0;
 }

 #ifdef CONFIG_DEBUG_FS
 static struct dentry *clk_debugfs_root;


 static void clock_tree_show_one(struct seq_file *s, struct clk *c, int level)
 {
 	struct clk *child;
 	struct clk *safe;
 	const char *state = "uninit";
 	char div[5] = {0};

 	if (c->state == ON)
 		state = "on";
 	else if (c->state == OFF)
 		state = "off";

 	if (c->mul != 0 && c->div != 0) {
 		BUG_ON(c->mul > 2);
 		if (c->mul > c->div)
 			snprintf(div, sizeof(div), "x%d", c->mul / c->div);
 		else
 			snprintf(div, sizeof(div), "%d%s", c->div / c->mul,
 				(c->div % c->mul) ? ".5" : "");
 	}

 	seq_printf(s, "%*s%-*s %-6s %-3d %-5s %-10lu\n",
 		level * 3 + 1, c->set ? "" : "*",
 		30 - level * 3, c->name,
 		state, c->refcnt, div, c->rate);
 	list_for_each_entry_safe(child, safe, &c->children, sibling) {
 		clock_tree_show_one(s, child, level + 1);
 	}
 }

 static int clock_tree_show(struct seq_file *s, void *data)
 {
 	struct clk *c;
 	unsigned long flags;
 	seq_printf(s, " clock                          state  ref div   rate      \n");
 	seq_printf(s, "-----------------------------------------------------------\n");
 	spin_lock_irqsave(&clock_lock, flags);
 	list_for_each_entry(c, &clocks, node)
 		if (c->parent == NULL)
 			clock_tree_show_one(s, c, 0);
 	spin_unlock_irqrestore(&clock_lock, flags);
 	return 0;
 }

 static int clock_tree_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, clock_tree_show, inode->i_private);
 }

 static const struct file_operations clock_tree_fops = {
 	.open		= clock_tree_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
 	.release	= single_release,
 };

 static int possible_parents_show(struct seq_file *s, void *data)
 {
 	struct clk *c = s->private;
 	int i;

 	for (i = 0; c->inputs[i].input; i++) {
 		char *first = (i == 0) ? "" : " ";
 		seq_printf(s, "%s%s", first, c->inputs[i].input->name);
 	}
 	seq_printf(s, "\n");
 	return 0;
 }

 static int possible_parents_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, possible_parents_show, inode->i_private);
 }

 static const struct file_operations possible_parents_fops = {
 	.open		= possible_parents_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
 	.release	= single_release,
 };

 static int clk_debugfs_register_one(struct clk *c)
 {
 	struct dentry *d, *child, *child_tmp;

 	d = debugfs_create_dir(c->name, clk_debugfs_root);
 	if (!d)
 		return -ENOMEM;
 	c->dent = d;

 	d = debugfs_create_u8("refcnt", S_IRUGO, c->dent, (u8 *)&c->refcnt);
 	if (!d)
 		goto err_out;

 	d = debugfs_create_u32("rate", S_IRUGO, c->dent, (u32 *)&c->rate);
 	if (!d)
 		goto err_out;

 	d = debugfs_create_x32("flags", S_IRUGO, c->dent, (u32 *)&c->flags);
 	if (!d)
 		goto err_out;

 	if (c->inputs) {
 		d = debugfs_create_file("possible_parents", S_IRUGO, c->dent,
 			c, &possible_parents_fops);
 		if (!d)
 			goto err_out;
 	}

 	return 0;

 err_out:
 	d = c->dent;
 	list_for_each_entry_safe(child, child_tmp, &d->d_subdirs, d_u.d_child)
 		debugfs_remove(child);
 	debugfs_remove(c->dent);
 	return -ENOMEM;
 }

 static int clk_debugfs_register(struct clk *c)
 {
 	int err;
 	struct clk *pa = c->parent;

 	if (pa && !pa->dent) {
 		err = clk_debugfs_register(pa);
 		if (err)
 			return err;
 	}

 	if (!c->dent) {
 		err = clk_debugfs_register_one(c);
 		if (err)
 			return err;
 	}
 	return 0;
 }

 static int __init clk_debugfs_init(void)
 {
 	struct clk *c;
 	struct dentry *d;
 	int err = -ENOMEM;

 	d = debugfs_create_dir("clock", NULL);
 	if (!d)
 		return -ENOMEM;
 	clk_debugfs_root = d;

 	d = debugfs_create_file("clock_tree", S_IRUGO, clk_debugfs_root, NULL,
 		&clock_tree_fops);
 	if (!d)
 		goto err_out;

 	list_for_each_entry(c, &clocks, node) {
 		err = clk_debugfs_register(c);
 		if (err)
 			goto err_out;
 	}
 	return 0;
 err_out:
 	debugfs_remove_recursive(clk_debugfs_root);
 	return err;
 }

 late_initcall(clk_debugfs_init);
 #endif
	/*
	*
	* Copyright (C) 2010 Google, Inc.
	*
	* Author:
	* Colin Cross <ccross@google.com>
	*
	* This software is licensed under the terms of the GNU General Public
	* License version 2, as published by the Free Software Foundation, and
	* may be copied, distributed, and modified under those terms.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	*/

	#include <linux/kernel.h>
	#include <linux/clk.h>
	#include <linux/list.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/debugfs.h>
	#include <linux/slab.h>
	#include <linux/seq_file.h>
	#include <asm/clkdev.h>

	#include "clock.h"

	static LIST_HEAD(clocks);

	static DEFINE_SPINLOCK(clock_lock);

	struct clk tegra_get_clock_by_name(const char name)
	{
	struct clk *c;
	struct clk *ret = NULL;
	unsigned long flags;
	spin_lock_irqsave(&clock_lock, flags);
	list_for_each_entry(c, &clocks, node) {
	if (strcmp(c->name, name) == 0) {
	ret = c;
	break;
	}
	}
	spin_unlock_irqrestore(&clock_lock, flags);
	return ret;
	}

	int clk_reparent(struct clk c, struct clk parent)
	{
	pr_debug("%s: %s\n", __func__, c->name);
	if (c->refcnt && c->parent)
	clk_disable_locked(c->parent);
	c->parent = parent;
	if (c->refcnt && c->parent)
	clk_enable_locked(c->parent);
	list_del(&c->sibling);
	list_add_tail(&c->sibling, &parent->children);
	return 0;
	}

	static void propagate_rate(struct clk *c)
	{
	struct clk *clkp;
	pr_debug("%s: %s\n", __func__, c->name);
	list_for_each_entry(clkp, &c->children, sibling) {
	pr_debug(" %s\n", clkp->name);
	if (clkp->ops->recalculate_rate)
	clkp->ops->recalculate_rate(clkp);
	propagate_rate(clkp);
	}
	}

	void clk_init(struct clk *c)
	{
	unsigned long flags;

	spin_lock_irqsave(&clock_lock, flags);

	INIT_LIST_HEAD(&c->children);
	INIT_LIST_HEAD(&c->sibling);

	if (c->ops && c->ops->init)
	c->ops->init(c);

	list_add(&c->node, &clocks);

	if (c->parent)
	list_add_tail(&c->sibling, &c->parent->children);

	spin_unlock_irqrestore(&clock_lock, flags);
	}

	int clk_enable_locked(struct clk *c)
	{
	int ret;
	pr_debug("%s: %s\n", __func__, c->name);
	if (c->refcnt == 0) {
	if (c->parent) {
	ret = clk_enable_locked(c->parent);
	if (ret)
	return ret;
	}

	if (c->ops && c->ops->enable) {
	ret = c->ops->enable(c);
	if (ret) {
	if (c->parent)
	clk_disable_locked(c->parent);
	return ret;
	}
	c->state = ON;
	#ifdef CONFIG_DEBUG_FS
	c->set = 1;
	#endif
	}
	}
	c->refcnt++;

	return 0;
	}

	int clk_enable(struct clk *c)
	{
	int ret;
	unsigned long flags;
	spin_lock_irqsave(&clock_lock, flags);
	ret = clk_enable_locked(c);
	spin_unlock_irqrestore(&clock_lock, flags);
	return ret;
	}
	EXPORT_SYMBOL(clk_enable);

	void clk_disable_locked(struct clk *c)
	{
	pr_debug("%s: %s\n", __func__, c->name);
	if (c->refcnt == 0) {
	WARN(1, "Attempting to disable clock %s with refcnt 0", c->name);
	return;
	}
	if (c->refcnt == 1) {
	if (c->ops && c->ops->disable)
	c->ops->disable(c);

	if (c->parent)
	clk_disable_locked(c->parent);

	c->state = OFF;
	}
	c->refcnt--;
	}

	void clk_disable(struct clk *c)
	{
	unsigned long flags;
	spin_lock_irqsave(&clock_lock, flags);
	clk_disable_locked(c);
	spin_unlock_irqrestore(&clock_lock, flags);
	}
	EXPORT_SYMBOL(clk_disable);

	int clk_set_parent_locked(struct clk c, struct clk parent)
	{
	int ret;

	pr_debug("%s: %s\n", __func__, c->name);

	if (!c->ops \|\| !c->ops->set_parent)
	return -ENOSYS;

	ret = c->ops->set_parent(c, parent);

	if (ret)
	return ret;

	propagate_rate(c);

	return 0;
	}

	int clk_set_parent(struct clk c, struct clk parent)
	{
	int ret;
	unsigned long flags;
	spin_lock_irqsave(&clock_lock, flags);
	ret = clk_set_parent_locked(c, parent);
	spin_unlock_irqrestore(&clock_lock, flags);
	return ret;
	}
	EXPORT_SYMBOL(clk_set_parent);

	struct clk clk_get_parent(struct clk c)
	{
	return c->parent;
	}
	EXPORT_SYMBOL(clk_get_parent);

	int clk_set_rate(struct clk *c, unsigned long rate)
	{
	int ret = 0;
	unsigned long flags;

	spin_lock_irqsave(&clock_lock, flags);

	pr_debug("%s: %s\n", __func__, c->name);

	if (c->ops && c->ops->set_rate)
	ret = c->ops->set_rate(c, rate);
	else
	ret = -ENOSYS;

	propagate_rate(c);

	spin_unlock_irqrestore(&clock_lock, flags);

	return ret;
	}
	EXPORT_SYMBOL(clk_set_rate);

	unsigned long clk_get_rate(struct clk *c)
	{
	unsigned long flags;
	unsigned long ret;

	spin_lock_irqsave(&clock_lock, flags);

	pr_debug("%s: %s\n", __func__, c->name);

	ret = c->rate;

	spin_unlock_irqrestore(&clock_lock, flags);
	return ret;
	}
	EXPORT_SYMBOL(clk_get_rate);

	static int tegra_clk_init_one_from_table(struct tegra_clk_init_table *table)
	{
	struct clk *c;
	struct clk *p;

	int ret = 0;

	c = tegra_get_clock_by_name(table->name);

	if (!c) {
	pr_warning("Unable to initialize clock %s\n",
	table->name);
	return -ENODEV;
	}

	if (table->parent) {
	p = tegra_get_clock_by_name(table->parent);
	if (!p) {
	pr_warning("Unable to find parent %s of clock %s\n",
	table->parent, table->name);
	return -ENODEV;
	}

	if (c->parent != p) {
	ret = clk_set_parent(c, p);
	if (ret) {
	pr_warning("Unable to set parent %s of clock %s: %d\n",
	table->parent, table->name, ret);
	return -EINVAL;
	}
	}
	}

	if (table->rate && table->rate != clk_get_rate(c)) {
	ret = clk_set_rate(c, table->rate);
	if (ret) {
	pr_warning("Unable to set clock %s to rate %lu: %d\n",
	table->name, table->rate, ret);
	return -EINVAL;
	}
	}

	if (table->enabled) {
	ret = clk_enable(c);
	if (ret) {
	pr_warning("Unable to enable clock %s: %d\n",
	table->name, ret);
	return -EINVAL;
	}
	}

	return 0;
	}

	void tegra_clk_init_from_table(struct tegra_clk_init_table *table)
	{
	for (; table->name; table++)
	tegra_clk_init_one_from_table(table);
	}
	EXPORT_SYMBOL(tegra_clk_init_from_table);

	void tegra_periph_reset_deassert(struct clk *c)
	{
	tegra2_periph_reset_deassert(c);
	}
	EXPORT_SYMBOL(tegra_periph_reset_deassert);

	void tegra_periph_reset_assert(struct clk *c)
	{
	tegra2_periph_reset_assert(c);
	}
	EXPORT_SYMBOL(tegra_periph_reset_assert);

	int __init tegra_init_clock(void)
	{
	tegra2_init_clocks();

	return 0;
	}

	#ifdef CONFIG_DEBUG_FS
	static struct dentry *clk_debugfs_root;


	static void clock_tree_show_one(struct seq_file s, struct clk c, int level)
	{
	struct clk *child;
	struct clk *safe;
	const char *state = "uninit";
	char div[5] = {0};

	if (c->state == ON)
	state = "on";
	else if (c->state == OFF)
	state = "off";

	if (c->mul != 0 && c->div != 0) {
	BUG_ON(c->mul > 2);
	if (c->mul > c->div)
	snprintf(div, sizeof(div), "x%d", c->mul / c->div);
	else
	snprintf(div, sizeof(div), "%d%s", c->div / c->mul,
	(c->div % c->mul) ? ".5" : "");
	}

	seq_printf(s, "%s%-s %-6s %-3d %-5s %-10lu\n",
	level * 3 + 1, c->set ? "" : "*",
	30 - level * 3, c->name,
	state, c->refcnt, div, c->rate);
	list_for_each_entry_safe(child, safe, &c->children, sibling) {
	clock_tree_show_one(s, child, level + 1);
	}
	}

	static int clock_tree_show(struct seq_file s, void data)
	{
	struct clk *c;
	unsigned long flags;
	seq_printf(s, " clock state ref div rate \n");
	seq_printf(s, "-----------------------------------------------------------\n");
	spin_lock_irqsave(&clock_lock, flags);
	list_for_each_entry(c, &clocks, node)
	if (c->parent == NULL)
	clock_tree_show_one(s, c, 0);
	spin_unlock_irqrestore(&clock_lock, flags);
	return 0;
	}

	static int clock_tree_open(struct inode inode, struct file file)
	{
	return single_open(file, clock_tree_show, inode->i_private);
	}

	static const struct file_operations clock_tree_fops = {
	.open = clock_tree_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = single_release,
	};

	static int possible_parents_show(struct seq_file s, void data)
	{
	struct clk *c = s->private;
	int i;

	for (i = 0; c->inputs[i].input; i++) {
	char *first = (i == 0) ? "" : " ";
	seq_printf(s, "%s%s", first, c->inputs[i].input->name);
	}
	seq_printf(s, "\n");
	return 0;
	}

	static int possible_parents_open(struct inode inode, struct file file)
	{
	return single_open(file, possible_parents_show, inode->i_private);
	}

	static const struct file_operations possible_parents_fops = {
	.open = possible_parents_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = single_release,
	};

	static int clk_debugfs_register_one(struct clk *c)
	{
	struct dentry d, child, *child_tmp;

	d = debugfs_create_dir(c->name, clk_debugfs_root);
	if (!d)
	return -ENOMEM;
	c->dent = d;

	d = debugfs_create_u8("refcnt", S_IRUGO, c->dent, (u8 *)&c->refcnt);
	if (!d)
	goto err_out;

	d = debugfs_create_u32("rate", S_IRUGO, c->dent, (u32 *)&c->rate);
	if (!d)
	goto err_out;

	d = debugfs_create_x32("flags", S_IRUGO, c->dent, (u32 *)&c->flags);
	if (!d)
	goto err_out;

	if (c->inputs) {
	d = debugfs_create_file("possible_parents", S_IRUGO, c->dent,
	c, &possible_parents_fops);
	if (!d)
	goto err_out;
	}

	return 0;

	err_out:
	d = c->dent;
	list_for_each_entry_safe(child, child_tmp, &d->d_subdirs, d_u.d_child)
	debugfs_remove(child);
	debugfs_remove(c->dent);
	return -ENOMEM;
	}

	static int clk_debugfs_register(struct clk *c)
	{
	int err;
	struct clk *pa = c->parent;

	if (pa && !pa->dent) {
	err = clk_debugfs_register(pa);
	if (err)
	return err;
	}

	if (!c->dent) {
	err = clk_debugfs_register_one(c);
	if (err)
	return err;
	}
	return 0;
	}

	static int __init clk_debugfs_init(void)
	{
	struct clk *c;
	struct dentry *d;
	int err = -ENOMEM;

	d = debugfs_create_dir("clock", NULL);
	if (!d)
	return -ENOMEM;
	clk_debugfs_root = d;

	d = debugfs_create_file("clock_tree", S_IRUGO, clk_debugfs_root, NULL,
	&clock_tree_fops);
	if (!d)
	goto err_out;

	list_for_each_entry(c, &clocks, node) {
	err = clk_debugfs_register(c);
	if (err)
	goto err_out;
	}
	return 0;
	err_out:
	debugfs_remove_recursive(clk_debugfs_root);
	return err;
	}

	late_initcall(clk_debugfs_init);
	#endif