text: /*
   * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
   * Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
   *
   * 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.
   *
   * Standard functionality for the common clock API.  See Documentation/clk.txt
   */
  
  #include <linux/clk-private.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/spinlock.h>
  #include <linux/err.h>
  #include <linux/list.h>
  #include <linux/slab.h>
  #include <linux/of.h>
  #include <linux/device.h>
  #include <linux/init.h>
  #include <linux/sched.h>
  
  static DEFINE_SPINLOCK(enable_lock);
  static DEFINE_MUTEX(prepare_lock);
  
  static struct task_struct *prepare_owner;
  static struct task_struct *enable_owner;
  
  static int prepare_refcnt;
  static int enable_refcnt;
  
  static HLIST_HEAD(clk_root_list);
  static HLIST_HEAD(clk_orphan_list);
  static LIST_HEAD(clk_notifier_list);
  
  /***           locking             ***/
  static void clk_prepare_lock(void)
  {
  	if (!mutex_trylock(&prepare_lock)) {
  		if (prepare_owner == current) {
  			prepare_refcnt++;
  			return;
  		}
  		mutex_lock(&prepare_lock);
  	}
  	WARN_ON_ONCE(prepare_owner != NULL);
  	WARN_ON_ONCE(prepare_refcnt != 0);
  	prepare_owner = current;
  	prepare_refcnt = 1;
  }
  
  static void clk_prepare_unlock(void)
  {
  	WARN_ON_ONCE(prepare_owner != current);
  	WARN_ON_ONCE(prepare_refcnt == 0);
  
  	if (--prepare_refcnt)
  		return;
  	prepare_owner = NULL;
  	mutex_unlock(&prepare_lock);
  }
  
  static unsigned long clk_enable_lock(void)
  {
  	unsigned long flags;
  
  	if (!spin_trylock_irqsave(&enable_lock, flags)) {
  		if (enable_owner == current) {
  			enable_refcnt++;
  			return flags;
  		}
  		spin_lock_irqsave(&enable_lock, flags);
  	}
  	WARN_ON_ONCE(enable_owner != NULL);
  	WARN_ON_ONCE(enable_refcnt != 0);
  	enable_owner = current;
  	enable_refcnt = 1;
  	return flags;
  }
  
  static void clk_enable_unlock(unsigned long flags)
  {
  	WARN_ON_ONCE(enable_owner != current);
  	WARN_ON_ONCE(enable_refcnt == 0);
  
  	if (--enable_refcnt)
  		return;
  	enable_owner = NULL;
  	spin_unlock_irqrestore(&enable_lock, flags);
  }
  
  /***        debugfs support        ***/
  
  #ifdef CONFIG_COMMON_CLK_DEBUG
  #include <linux/debugfs.h>
  
  static struct dentry *rootdir;
  static struct dentry *orphandir;
  static int inited = 0;
  
  static void clk_summary_show_one(struct seq_file *s, struct clk *c, int level)
  {
  	if (!c)
  		return;
  
  	seq_printf(s, "%*s%-*s %-11d %-12d %-10lu",
  		   level * 3 + 1, "",
  		   30 - level * 3, c->name,
  		   c->enable_count, c->prepare_count, c->rate);
  	seq_printf(s, "\n");
  }
  
  static void clk_summary_show_subtree(struct seq_file *s, struct clk *c,
  				     int level)
  {
  	struct clk *child;
  
  	if (!c)
  		return;
  
  	clk_summary_show_one(s, c, level);
  
  	hlist_for_each_entry(child, &c->children, child_node)
  		clk_summary_show_subtree(s, child, level + 1);
  }
  
  static int clk_summary_show(struct seq_file *s, void *data)
  {
  	struct clk *c;
  
  	seq_printf(s, "   clock                        enable_cnt  prepare_cnt  rate\n");
  	seq_printf(s, "---------------------------------------------------------------------\n");
  
  	clk_prepare_lock();
  
  	hlist_for_each_entry(c, &clk_root_list, child_node)
  		clk_summary_show_subtree(s, c, 0);
  
  	hlist_for_each_entry(c, &clk_orphan_list, child_node)
  		clk_summary_show_subtree(s, c, 0);
  
  	clk_prepare_unlock();
  
  	return 0;
  }
  
  
  static int clk_summary_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, clk_summary_show, inode->i_private);
  }
  
  static const struct file_operations clk_summary_fops = {
  	.open		= clk_summary_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };
  
  static void clk_dump_one(struct seq_file *s, struct clk *c, int level)
  {
  	if (!c)
  		return;
  
  	seq_printf(s, "\"%s\": { ", c->name);
  	seq_printf(s, "\"enable_count\": %d,", c->enable_count);
  	seq_printf(s, "\"prepare_count\": %d,", c->prepare_count);
  	seq_printf(s, "\"rate\": %lu", c->rate);
  }
  
  static void clk_dump_subtree(struct seq_file *s, struct clk *c, int level)
  {
  	struct clk *child;
  
  	if (!c)
  		return;
  
  	clk_dump_one(s, c, level);
  
  	hlist_for_each_entry(child, &c->children, child_node) {
  		seq_printf(s, ",");
  		clk_dump_subtree(s, child, level + 1);
  	}
  
  	seq_printf(s, "}");
  }
  
  static int clk_dump(struct seq_file *s, void *data)
  {
  	struct clk *c;
  	bool first_node = true;
  
  	seq_printf(s, "{");
  
  	clk_prepare_lock();
  
  	hlist_for_each_entry(c, &clk_root_list, child_node) {
  		if (!first_node)
  			seq_printf(s, ",");
  		first_node = false;
  		clk_dump_subtree(s, c, 0);
  	}
  
  	hlist_for_each_entry(c, &clk_orphan_list, child_node) {
  		seq_printf(s, ",");
  		clk_dump_subtree(s, c, 0);
  	}
  
  	clk_prepare_unlock();
  
  	seq_printf(s, "}");
  	return 0;
  }
  
  
  static int clk_dump_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, clk_dump, inode->i_private);
  }
  
  static const struct file_operations clk_dump_fops = {
  	.open		= clk_dump_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };
  
  /* caller must hold prepare_lock */
  static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry)
  {
  	struct dentry *d;
  	int ret = -ENOMEM;
  
  	if (!clk || !pdentry) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	d = debugfs_create_dir(clk->name, pdentry);
  	if (!d)
  		goto out;
  
  	clk->dentry = d;
  
  	d = debugfs_create_u32("clk_rate", S_IRUGO, clk->dentry,
  			(u32 *)&clk->rate);
  	if (!d)
  		goto err_out;
  
  	d = debugfs_create_x32("clk_flags", S_IRUGO, clk->dentry,
  			(u32 *)&clk->flags);
  	if (!d)
  		goto err_out;
  
  	d = debugfs_create_u32("clk_prepare_count", S_IRUGO, clk->dentry,
  			(u32 *)&clk->prepare_count);
  	if (!d)
  		goto err_out;
  
  	d = debugfs_create_u32("clk_enable_count", S_IRUGO, clk->dentry,
  			(u32 *)&clk->enable_count);
  	if (!d)
  		goto err_out;
  
  	d = debugfs_create_u32("clk_notifier_count", S_IRUGO, clk->dentry,
  			(u32 *)&clk->notifier_count);
  	if (!d)
  		goto err_out;
  
  	ret = 0;
  	goto out;
  
  err_out:
  	debugfs_remove(clk->dentry);
  out:
  	return ret;
  }
  
  /* caller must hold prepare_lock */
  static int clk_debug_create_subtree(struct clk *clk, struct dentry *pdentry)
  {
  	struct clk *child;
  	int ret = -EINVAL;;
  
  	if (!clk || !pdentry)
  		goto out;
  
  	ret = clk_debug_create_one(clk, pdentry);
  
  	if (ret)
  		goto out;
  
  	hlist_for_each_entry(child, &clk->children, child_node)
  		clk_debug_create_subtree(child, clk->dentry);
  
  	ret = 0;
  out:
  	return ret;
  }
  
  /**
   * clk_debug_register - add a clk node to the debugfs clk tree
   * @clk: the clk being added to the debugfs clk tree
   *
   * Dynamically adds a clk to the debugfs clk tree if debugfs has been
   * initialized.  Otherwise it bails out early since the debugfs clk tree
   * will be created lazily by clk_debug_init as part of a late_initcall.
   *
   * Caller must hold prepare_lock.  Only clk_init calls this function (so
   * far) so this is taken care.
   */
  static int clk_debug_register(struct clk *clk)
  {
  	struct clk *parent;
  	struct dentry *pdentry;
  	int ret = 0;
  
  	if (!inited)
  		goto out;
  
  	parent = clk->parent;
  
  	/*
  	 * Check to see if a clk is a root clk.  Also check that it is
  	 * safe to add this clk to debugfs
  	 */
  	if (!parent)
  		if (clk->flags & CLK_IS_ROOT)
  			pdentry = rootdir;
  		else
  			pdentry = orphandir;
  	else
  		if (parent->dentry)
  			pdentry = parent->dentry;
  		else
  			goto out;
  
  	ret = clk_debug_create_subtree(clk, pdentry);
  
  out:
  	return ret;
  }
  
  /**
   * clk_debug_reparent - reparent clk node in the debugfs clk tree
   * @clk: the clk being reparented
   * @new_parent: the new clk parent, may be NULL
   *
   * Rename clk entry in the debugfs clk tree if debugfs has been
   * initialized.  Otherwise it bails out early since the debugfs clk tree
   * will be created lazily by clk_debug_init as part of a late_initcall.
   *
   * Caller must hold prepare_lock.
   */
  static void clk_debug_reparent(struct clk *clk, struct clk *new_parent)
  {
  	struct dentry *d;
  	struct dentry *new_parent_d;
  
  	if (!inited)
  		return;
  
  	if (new_parent)
  		new_parent_d = new_parent->dentry;
  	else
  		new_parent_d = orphandir;
  
  	d = debugfs_rename(clk->dentry->d_parent, clk->dentry,
  			new_parent_d, clk->name);
  	if (d)
  		clk->dentry = d;
  	else
  		pr_debug("%s: failed to rename debugfs entry for %s\n",
  				__func__, clk->name);
  }
  
  /**
   * clk_debug_init - lazily create the debugfs clk tree visualization
   *
   * clks are often initialized very early during boot before memory can
   * be dynamically allocated and well before debugfs is setup.
   * clk_debug_init walks the clk tree hierarchy while holding
   * prepare_lock and creates the topology as part of a late_initcall,
   * thus insuring that clks initialized very early will still be
   * represented in the debugfs clk tree.  This function should only be
   * called once at boot-time, and all other clks added dynamically will
   * be done so with clk_debug_register.
   */
  static int __init clk_debug_init(void)
  {
  	struct clk *clk;
  	struct dentry *d;
  
  	rootdir = debugfs_create_dir("clk", NULL);
  
  	if (!rootdir)
  		return -ENOMEM;
  
  	d = debugfs_create_file("clk_summary", S_IRUGO, rootdir, NULL,
  				&clk_summary_fops);
  	if (!d)
  		return -ENOMEM;
  
  	d = debugfs_create_file("clk_dump", S_IRUGO, rootdir, NULL,
  				&clk_dump_fops);
  	if (!d)
  		return -ENOMEM;
  
  	orphandir = debugfs_create_dir("orphans", rootdir);
  
  	if (!orphandir)
  		return -ENOMEM;
  
  	clk_prepare_lock();
  
  	hlist_for_each_entry(clk, &clk_root_list, child_node)
  		clk_debug_create_subtree(clk, rootdir);
  
  	hlist_for_each_entry(clk, &clk_orphan_list, child_node)
  		clk_debug_create_subtree(clk, orphandir);
  
  	inited = 1;
  
  	clk_prepare_unlock();
  
  	return 0;
  }
  late_initcall(clk_debug_init);
  #else
  static inline int clk_debug_register(struct clk *clk) { return 0; }
  static inline void clk_debug_reparent(struct clk *clk, struct clk *new_parent)
  {
  }
  #endif
  
  /* caller must hold prepare_lock */
  static void clk_unprepare_unused_subtree(struct clk *clk)
  {
  	struct clk *child;
  
  	if (!clk)
  		return;
  
  	hlist_for_each_entry(child, &clk->children, child_node)
  		clk_unprepare_unused_subtree(child);
  
  	if (clk->prepare_count)
  		return;
  
  	if (clk->flags & CLK_IGNORE_UNUSED)
  		return;
  
  	if (__clk_is_prepared(clk)) {
  		if (clk->ops->unprepare_unused)
  			clk->ops->unprepare_unused(clk->hw);
  		else if (clk->ops->unprepare)
  			clk->ops->unprepare(clk->hw);
  	}
  }
  EXPORT_SYMBOL_GPL(__clk_get_flags);
  
  /* caller must hold prepare_lock */
  static void clk_disable_unused_subtree(struct clk *clk)
  {
  	struct clk *child;
  	unsigned long flags;
  
  	if (!clk)
  		goto out;
  
  	hlist_for_each_entry(child, &clk->children, child_node)
  		clk_disable_unused_subtree(child);
  
  	flags = clk_enable_lock();
  
  	if (clk->enable_count)
  		goto unlock_out;
  
  	if (clk->flags & CLK_IGNORE_UNUSED)
  		goto unlock_out;
  
  	/*
  	 * some gate clocks have special needs during the disable-unused
  	 * sequence.  call .disable_unused if available, otherwise fall
  	 * back to .disable
  	 */
  	if (__clk_is_enabled(clk)) {
  		if (clk->ops->disable_unused)
  			clk->ops->disable_unused(clk->hw);
  		else if (clk->ops->disable)
  			clk->ops->disable(clk->hw);
  	}
  
  unlock_out:
  	clk_enable_unlock(flags);
  
  out:
  	return;
  }
  
  static bool clk_ignore_unused;
  static int __init clk_ignore_unused_setup(char *__unused)
  {
  	clk_ignore_unused = true;
  	return 1;
  }
  __setup("clk_ignore_unused", clk_ignore_unused_setup);
  
  static int clk_disable_unused(void)
  {
  	struct clk *clk;
  
  	if (clk_ignore_unused) {
  		pr_warn("clk: Not disabling unused clocks\n");
  		return 0;
  	}
  
  	clk_prepare_lock();
  
  	hlist_for_each_entry(clk, &clk_root_list, child_node)
  		clk_disable_unused_subtree(clk);
  
  	hlist_for_each_entry(clk, &clk_orphan_list, child_node)
  		clk_disable_unused_subtree(clk);
  
  	hlist_for_each_entry(clk, &clk_root_list, child_node)
  		clk_unprepare_unused_subtree(clk);
  
  	hlist_for_each_entry(clk, &clk_orphan_list, child_node)
  		clk_unprepare_unused_subtree(clk);
  
  	clk_prepare_unlock();
  
  	return 0;
  }
  late_initcall(clk_disable_unused);
  
  /***    helper functions   ***/
  
  const char *__clk_get_name(struct clk *clk)
  {
  	return !clk ? NULL : clk->name;
  }
  EXPORT_SYMBOL_GPL(__clk_get_name);
  
  struct clk_hw *__clk_get_hw(struct clk *clk)
  {
  	return !clk ? NULL : clk->hw;
  }
  
  u8 __clk_get_num_parents(struct clk *clk)
  {
  	return !clk ? 0 : clk->num_parents;
  }
  
  struct clk *__clk_get_parent(struct clk *clk)
  {
  	return !clk ? NULL : clk->parent;
  }
  
  unsigned int __clk_get_enable_count(struct clk *clk)
  {
  	return !clk ? 0 : clk->enable_count;
  }
  
  unsigned int __clk_get_prepare_count(struct clk *clk)
  {
  	return !clk ? 0 : clk->prepare_count;
  }
  
  unsigned long __clk_get_rate(struct clk *clk)
  {
  	unsigned long ret;
  
  	if (!clk) {
  		ret = 0;
  		goto out;
  	}
  
  	ret = clk->rate;
  
  	if (clk->flags & CLK_IS_ROOT)
  		goto out;
  
  	if (!clk->parent)
  		ret = 0;
  
  out:
  	return ret;
  }
  
  unsigned long __clk_get_flags(struct clk *clk)
  {
  	return !clk ? 0 : clk->flags;
  }
  
  bool __clk_is_prepared(struct clk *clk)
  {
  	int ret;
  
  	if (!clk)
  		return false;
  
  	/*
  	 * .is_prepared is optional for clocks that can prepare
  	 * fall back to software usage counter if it is missing
  	 */
  	if (!clk->ops->is_prepared) {
  		ret = clk->prepare_count ? 1 : 0;
  		goto out;
  	}
  
  	ret = clk->ops->is_prepared(clk->hw);
  out:
  	return !!ret;
  }
  
  bool __clk_is_enabled(struct clk *clk)
  {
  	int ret;
  
  	if (!clk)
  		return false;
  
  	/*
  	 * .is_enabled is only mandatory for clocks that gate
  	 * fall back to software usage counter if .is_enabled is missing
  	 */
  	if (!clk->ops->is_enabled) {
  		ret = clk->enable_count ? 1 : 0;
  		goto out;
  	}
  
  	ret = clk->ops->is_enabled(clk->hw);
  out:
  	return !!ret;
  }
  
  static struct clk *__clk_lookup_subtree(const char *name, struct clk *clk)
  {
  	struct clk *child;
  	struct clk *ret;
  
  	if (!strcmp(clk->name, name))
  		return clk;
  
  	hlist_for_each_entry(child, &clk->children, child_node) {
  		ret = __clk_lookup_subtree(name, child);
  		if (ret)
  			return ret;
  	}
  
  	return NULL;
  }
  
  struct clk *__clk_lookup(const char *name)
  {
  	struct clk *root_clk;
  	struct clk *ret;
  
  	if (!name)
  		return NULL;
  
  	/* search the 'proper' clk tree first */
  	hlist_for_each_entry(root_clk, &clk_root_list, child_node) {
  		ret = __clk_lookup_subtree(name, root_clk);
  		if (ret)
  			return ret;
  	}
  
  	/* if not found, then search the orphan tree */
  	hlist_for_each_entry(root_clk, &clk_orphan_list, child_node) {
  		ret = __clk_lookup_subtree(name, root_clk);
  		if (ret)
  			return ret;
  	}
  
  	return NULL;
  }
  EXPORT_SYMBOL(__clk_lookup);
  
  /***        clk api        ***/
  
  void __clk_unprepare(struct clk *clk)
  {
  	if (!clk)
  		return;
  
  	if (WARN_ON(clk->prepare_count == 0))
  		return;
  
  	if (--clk->prepare_count > 0)
  		return;
  
  	WARN_ON(clk->enable_count > 0);
  
  	if (clk->ops->unprepare)
  		clk->ops->unprepare(clk->hw);
  
  	__clk_unprepare(clk->parent);
  }
  
  /**
   * clk_unprepare - undo preparation of a clock source
   * @clk: the clk being unprepare
   *
   * clk_unprepare may sleep, which differentiates it from clk_disable.  In a
   * simple case, clk_unprepare can be used instead of clk_disable to gate a clk
   * if the operation may sleep.  One example is a clk which is accessed over
   * I2c.  In the complex case a clk gate operation may require a fast and a slow
   * part.  It is this reason that clk_unprepare and clk_disable are not mutually
   * exclusive.  In fact clk_disable must be called before clk_unprepare.
   */
  void clk_unprepare(struct clk *clk)
  {
  	clk_prepare_lock();
  	__clk_unprepare(clk);
  	clk_prepare_unlock();
  }
  EXPORT_SYMBOL_GPL(clk_unprepare);
  
  int __clk_prepare(struct clk *clk)
  {
  	int ret = 0;
  
  	if (!clk)
  		return 0;
  
  	if (clk->prepare_count == 0) {
  		ret = __clk_prepare(clk->parent);
  		if (ret)
  			return ret;
  
  		if (clk->ops->prepare) {
  			ret = clk->ops->prepare(clk->hw);
  			if (ret) {
  				__clk_unprepare(clk->parent);
  				return ret;
  			}
  		}
  	}
  
  	clk->prepare_count++;
  
  	return 0;
  }
  
  /**
   * clk_prepare - prepare a clock source
   * @clk: the clk being prepared
   *
   * clk_prepare may sleep, which differentiates it from clk_enable.  In a simple
   * case, clk_prepare can be used instead of clk_enable to ungate a clk if the
   * operation may sleep.  One example is a clk which is accessed over I2c.  In
   * the complex case a clk ungate operation may require a fast and a slow part.
   * It is this reason that clk_prepare and clk_enable are not mutually
   * exclusive.  In fact clk_prepare must be called before clk_enable.
   * Returns 0 on success, -EERROR otherwise.
   */
  int clk_prepare(struct clk *clk)
  {
  	int ret;
  
  	clk_prepare_lock();
  	ret = __clk_prepare(clk);
  	clk_prepare_unlock();
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(clk_prepare);
  
  static void __clk_disable(struct clk *clk)
  {
  	if (!clk)
  		return;
  
  	if (WARN_ON(IS_ERR(clk)))
  		return;
  
  	if (WARN_ON(clk->enable_count == 0))
  		return;
  
  	if (--clk->enable_count > 0)
  		return;
  
  	if (clk->ops->disable)
  		clk->ops->disable(clk->hw);
  
  	__clk_disable(clk->parent);
  }
  
  /**
   * clk_disable - gate a clock
   * @clk: the clk being gated
   *
   * clk_disable must not sleep, which differentiates it from clk_unprepare.  In
   * a simple case, clk_disable can be used instead of clk_unprepare to gate a
   * clk if the operation is fast and will never sleep.  One example is a
   * SoC-internal clk which is controlled via simple register writes.  In the
   * complex case a clk gate operation may require a fast and a slow part.  It is
   * this reason that clk_unprepare and clk_disable are not mutually exclusive.
   * In fact clk_disable must be called before clk_unprepare.
   */
  void clk_disable(struct clk *clk)
  {
  	unsigned long flags;
  
  	flags = clk_enable_lock();
  	__clk_disable(clk);
  	clk_enable_unlock(flags);
  }
  EXPORT_SYMBOL_GPL(clk_disable);
  
  static int __clk_enable(struct clk *clk)
  {
  	int ret = 0;
  
  	if (!clk)
  		return 0;
  
  	if (WARN_ON(clk->prepare_count == 0))
  		return -ESHUTDOWN;
  
  	if (clk->enable_count == 0) {
  		ret = __clk_enable(clk->parent);
  
  		if (ret)
  			return ret;
  
  		if (clk->ops->enable) {
  			ret = clk->ops->enable(clk->hw);
  			if (ret) {
  				__clk_disable(clk->parent);
  				return ret;
  			}
  		}
  	}
  
  	clk->enable_count++;
  	return 0;
  }
  
  /**
   * clk_enable - ungate a clock
   * @clk: the clk being ungated
   *
   * clk_enable must not sleep, which differentiates it from clk_prepare.  In a
   * simple case, clk_enable can be used instead of clk_prepare to ungate a clk
   * if the operation will never sleep.  One example is a SoC-internal clk which
   * is controlled via simple register writes.  In the complex case a clk ungate
   * operation may require a fast and a slow part.  It is this reason that
   * clk_enable and clk_prepare are not mutually exclusive.  In fact clk_prepare
   * must be called before clk_enable.  Returns 0 on success, -EERROR
   * otherwise.
   */
  int clk_enable(struct clk *clk)
  {
  	unsigned long flags;
  	int ret;
  
  	flags = clk_enable_lock();
  	ret = __clk_enable(clk);
  	clk_enable_unlock(flags);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(clk_enable);
  
  /**
   * __clk_round_rate - round the given rate for a clk
   * @clk: round the rate of this clock
   *
   * Caller must hold prepare_lock.  Useful for clk_ops such as .set_rate
   */
  unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
  {
  	unsigned long parent_rate = 0;
  
  	if (!clk)
  		return 0;
  
  	if (!clk->ops->round_rate) {
  		if (clk->flags & CLK_SET_RATE_PARENT)
  			return __clk_round_rate(clk->parent, rate);
  		else
  			return clk->rate;
  	}
  
  	if (clk->parent)
  		parent_rate = clk->parent->rate;
  
  	return clk->ops->round_rate(clk->hw, rate, &parent_rate);
  }
  
  /**
   * clk_round_rate - round the given rate for a clk
   * @clk: the clk for which we are rounding a rate
   * @rate: the rate which is to be rounded
   *
   * Takes in a rate as input and rounds it to a rate that the clk can actually
   * use which is then returned.  If clk doesn't support round_rate operation
   * then the parent rate is returned.
   */
  long clk_round_rate(struct clk *clk, unsigned long rate)
  {
  	unsigned long ret;
  
  	clk_prepare_lock();
  	ret = __clk_round_rate(clk, rate);
  	clk_prepare_unlock();
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(clk_round_rate);
  
  /**
   * __clk_notify - call clk notifier chain
   * @clk: struct clk * that is changing rate
   * @msg: clk notifier type (see include/linux/clk.h)
   * @old_rate: old clk rate
   * @new_rate: new clk rate
   *
   * Triggers a notifier call chain on the clk rate-change notification
   * for 'clk'.  Passes a pointer to the struct clk and the previous
   * and current rates to the notifier callback.  Intended to be called by
   * internal clock code only.  Returns NOTIFY_DONE from the last driver
   * called if all went well, or NOTIFY_STOP or NOTIFY_BAD immediately if
   * a driver returns that.
   */
  static int __clk_notify(struct clk *clk, unsigned long msg,
  		unsigned long old_rate, unsigned long new_rate)
  {
  	struct clk_notifier *cn;
  	struct clk_notifier_data cnd;
  	int ret = NOTIFY_DONE;
  
  	cnd.clk = clk;
  	cnd.old_rate = old_rate;
  	cnd.new_rate = new_rate;
  
  	list_for_each_entry(cn, &clk_notifier_list, node) {
  		if (cn->clk == clk) {
  			ret = srcu_notifier_call_chain(&cn->notifier_head, msg,
  					&cnd);
  			break;
  		}
  	}
  
  	return ret;
  }
  
  /**
   * __clk_recalc_rates
   * @clk: first clk in the subtree
   * @msg: notification type (see include/linux/clk.h)
   *
   * Walks the subtree of clks starting with clk and recalculates rates as it
   * goes.  Note that if a clk does not implement the .recalc_rate callback then
   * it is assumed that the clock will take on the rate of it's parent.
   *
   * clk_recalc_rates also propagates the POST_RATE_CHANGE notification,
   * if necessary.
   *
   * Caller must hold prepare_lock.
   */
  static void __clk_recalc_rates(struct clk *clk, unsigned long msg)
  {
  	unsigned long old_rate;
  	unsigned long parent_rate = 0;
  	struct clk *child;
  
  	old_rate = clk->rate;
  
  	if (clk->parent)
  		parent_rate = clk->parent->rate;
  
  	if (clk->ops->recalc_rate)
  		clk->rate = clk->ops->recalc_rate(clk->hw, parent_rate);
  	else
  		clk->rate = parent_rate;
  
  	/*
  	 * ignore NOTIFY_STOP and NOTIFY_BAD return values for POST_RATE_CHANGE
  	 * & ABORT_RATE_CHANGE notifiers
  	 */
  	if (clk->notifier_count && msg)
  		__clk_notify(clk, msg, old_rate, clk->rate);
  
  	hlist_for_each_entry(child, &clk->children, child_node)
  		__clk_recalc_rates(child, msg);
  }
  
  /**
   * clk_get_rate - return the rate of clk
   * @clk: the clk whose rate is being returned
   *
   * Simply returns the cached rate of the clk, unless CLK_GET_RATE_NOCACHE flag
   * is set, which means a recalc_rate will be issued.
   * If clk is NULL then returns 0.
   */
  unsigned long clk_get_rate(struct clk *clk)
  {
  	unsigned long rate;
  
  	clk_prepare_lock();
  
  	if (clk && (clk->flags & CLK_GET_RATE_NOCACHE))
  		__clk_recalc_rates(clk, 0);
  
  	rate = __clk_get_rate(clk);
  	clk_prepare_unlock();
  
  	return rate;
  }
  EXPORT_SYMBOL_GPL(clk_get_rate);
  
  /**
   * __clk_speculate_rates
   * @clk: first clk in the subtree
   * @parent_rate: the "future" rate of clk's parent
   *
   * Walks the subtree of clks starting with clk, speculating rates as it
   * goes and firing off PRE_RATE_CHANGE notifications as necessary.
   *
   * Unlike clk_recalc_rates, clk_speculate_rates exists only for sending
   * pre-rate change notifications and returns early if no clks in the
   * subtree have subscribed to the notifications.  Note that if a clk does not
   * implement the .recalc_rate callback then it is assumed that the clock will
   * take on the rate of it's parent.
   *
   * Caller must hold prepare_lock.
   */
  static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate)
  {
  	struct clk *child;
  	unsigned long new_rate;
  	int ret = NOTIFY_DONE;
  
  	if (clk->ops->recalc_rate)
  		new_rate = clk->ops->recalc_rate(clk->hw, parent_rate);
  	else
  		new_rate = parent_rate;
  
  	/* abort rate change if a driver returns NOTIFY_BAD or NOTIFY_STOP */
  	if (clk->notifier_count)
  		ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate);
  
  	if (ret & NOTIFY_STOP_MASK)
  		goto out;
  
  	hlist_for_each_entry(child, &clk->children, child_node) {
  		ret = __clk_speculate_rates(child, new_rate);
  		if (ret & NOTIFY_STOP_MASK)
  			break;
  	}
  
  out:
  	return ret;
  }
  
  static void clk_calc_subtree(struct clk *clk, unsigned long new_rate)
  {
  	struct clk *child;
  
  	clk->new_rate = new_rate;
  
  	hlist_for_each_entry(child, &clk->children, child_node) {
  		if (child->ops->recalc_rate)
  			child->new_rate = child->ops->recalc_rate(child->hw, new_rate);
  		else
  			child->new_rate = new_rate;
  		clk_calc_subtree(child, child->new_rate);
  	}
  }
  
  /*
   * calculate the new rates returning the topmost clock that has to be
   * changed.
   */
  static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
  {
  	struct clk *top = clk;
  	unsigned long best_parent_rate = 0;
  	unsigned long new_rate;
  
  	/* sanity */
  	if (IS_ERR_OR_NULL(clk))
  		return NULL;
  
  	/* save parent rate, if it exists */
  	if (clk->parent)
  		best_parent_rate = clk->parent->rate;
  
  	/* never propagate up to the parent */
  	if (!(clk->flags & CLK_SET_RATE_PARENT)) {
  		if (!clk->ops->round_rate) {
  			clk->new_rate = clk->rate;
  			return NULL;
  		}
  		new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
  		goto out;
  	}
  
  	/* need clk->parent from here on out */
  	if (!clk->parent) {
  		pr_debug("%s: %s has NULL parent\n", __func__, clk->name);
  		return NULL;
  	}
  
  	if (!clk->ops->round_rate) {
  		top = clk_calc_new_rates(clk->parent, rate);
  		new_rate = clk->parent->new_rate;
  
  		goto out;
  	}
  
  	new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
  
  	if (best_parent_rate != clk->parent->rate) {
  		top = clk_calc_new_rates(clk->parent, best_parent_rate);
  
  		goto out;
  	}
  
  out:
  	clk_calc_subtree(clk, new_rate);
  
  	return top;
  }
  
  /*
   * Notify about rate changes in a subtree. Always walk down the whole tree
   * so that in case of an error we can walk down the whole tree again and
   * abort the change.
   */
  static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long event)
  {
  	struct clk *child, *fail_clk = NULL;
  	int ret = NOTIFY_DONE;
  
  	if (clk->rate == clk->new_rate)
  		return NULL;
  
  	if (clk->notifier_count) {
  		ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
  		if (ret & NOTIFY_STOP_MASK)
  			fail_clk = clk;
  	}
  
  	hlist_for_each_entry(child, &clk->children, child_node) {
  		clk = clk_propagate_rate_change(child, event);
  		if (clk)
  			fail_clk = clk;
  	}
  
  	return fail_clk;
  }
  
  /*
   * walk down a subtree and set the new rates notifying the rate
   * change on the way
   */
  static void clk_change_rate(struct clk *clk)
  {
  	struct clk *child;
  	unsigned long old_rate;
  	unsigned long best_parent_rate = 0;
  
  	old_rate = clk->rate;
  
  	if (clk->parent)
  		best_parent_rate = clk->parent->rate;
  
  	if (clk->ops->set_rate)
  		clk->ops->set_rate(clk->hw, clk->new_rate, best_parent_rate);
  
  	if (clk->ops->recalc_rate)
  		clk->rate = clk->ops->recalc_rate(clk->hw, best_parent_rate);
  	else
  		clk->rate = best_parent_rate;
  
  	if (clk->notifier_count && old_rate != clk->rate)
  		__clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate);
  
  	hlist_for_each_entry(child, &clk->children, child_node)
  		clk_change_rate(child);
  }
  
  /**
   * clk_set_rate - specify a new rate for clk
   * @clk: the clk whose rate is being changed
   * @rate: the new rate for clk
   *
   * In the simplest case clk_set_rate will only adjust the rate of clk.
   *
   * Setting the CLK_SET_RATE_PARENT flag allows the rate change operation to
   * propagate up to clk's parent; whether or not this happens depends on the
   * outcome of clk's .round_rate implementation.  If *parent_rate is unchanged
   * after calling .round_rate then upstream parent propagation is ignored.  If
   * *parent_rate comes back with a new rate for clk's parent then we propagate
   * up to clk's parent and set it's rate.  Upward propagation will continue
   * until either a clk does not support the CLK_SET_RATE_PARENT flag or
   * .round_rate stops requesting changes to clk's parent_rate.
   *
   * Rate changes are accomplished via tree traversal that also recalculates the
   * rates for the clocks and fires off POST_RATE_CHANGE notifiers.
   *
   * Returns 0 on success, -EERROR otherwise.
   */
  int clk_set_rate(struct clk *clk, unsigned long rate)
  {
  	struct clk *top, *fail_clk;
  	int ret = 0;
  
  	/* prevent racing with updates to the clock topology */
  	clk_prepare_lock();
  
  	/* bail early if nothing to do */
  	if (rate == clk->rate)
  		goto out;
  
  	if ((clk->flags & CLK_SET_RATE_GATE) && clk->prepare_count) {
  		ret = -EBUSY;
  		goto out;
  	}
  
  	/* calculate new rates and get the topmost changed clock */
  	top = clk_calc_new_rates(clk, rate);
  	if (!top) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	/* notify that we are about to change rates */
  	fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
  	if (fail_clk) {
  		pr_warn("%s: failed to set %s rate\n", __func__,
  				fail_clk->name);
  		clk_propagate_rate_change(top, ABORT_RATE_CHANGE);
  		ret = -EBUSY;
  		goto out;
  	}
  
  	/* change the rates */
  	clk_change_rate(top);
  
  out:
  	clk_prepare_unlock();
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(clk_set_rate);
  
  /**
   * clk_get_parent - return the parent of a clk
   * @clk: the clk whose parent gets returned
   *
   * Simply returns clk->parent.  Returns NULL if clk is NULL.
   */
  struct clk *clk_get_parent(struct clk *clk)
  {
  	struct clk *parent;
  
  	clk_prepare_lock();
  	parent = __clk_get_parent(clk);
  	clk_prepare_unlock();
  
  	return parent;
  }
  EXPORT_SYMBOL_GPL(clk_get_parent);
  
  /*
   * .get_parent is mandatory for clocks with multiple possible parents.  It is
   * optional for single-parent clocks.  Always call .get_parent if it is
   * available and WARN if it is missing for multi-parent clocks.
   *
   * For single-parent clocks without .get_parent, first check to see if the
   * .parents array exists, and if so use it to avoid an expensive tree
   * traversal.  If .parents does not exist then walk the tree with __clk_lookup.
   */
  static struct clk *__clk_init_parent(struct clk *clk)
  {
  	struct clk *ret = NULL;
  	u8 index;
  
  	/* handle the trivial cases */
  
  	if (!clk->num_parents)
  		goto out;
  
  	if (clk->num_parents == 1) {
  		if (IS_ERR_OR_NULL(clk->parent))
  			ret = clk->parent = __clk_lookup(clk->parent_names[0]);
  		ret = clk->parent;
  		goto out;
  	}
  
  	if (!clk->ops->get_parent) {
  		WARN(!clk->ops->get_parent,
  			"%s: multi-parent clocks must implement .get_parent\n",
  			__func__);
  		goto out;
  	};
  
  	/*
  	 * Do our best to cache parent clocks in clk->parents.  This prevents
  	 * unnecessary and expensive calls to __clk_lookup.  We don't set
  	 * clk->parent here; that is done by the calling function
  	 */
  
  	index = clk->ops->get_parent(clk->hw);
  
  	if (!clk->parents)
  		clk->parents =
  			kzalloc((sizeof(struct clk*) * clk->num_parents),
  					GFP_KERNEL);
  
  	if (!clk->parents)
  		ret = __clk_lookup(clk->parent_names[index]);
  	else if (!clk->parents[index])
  		ret = clk->parents[index] =
  			__clk_lookup(clk->parent_names[index]);
  	else
  		ret = clk->parents[index];
  
  out:
  	return ret;
  }
  
  static void clk_reparent(struct clk *clk, struct clk *new_parent)
  {
  	hlist_del(&clk->child_node);
  
  	if (new_parent)
  		hlist_add_head(&clk->child_node, &new_parent->children);
  	else
  		hlist_add_head(&clk->child_node, &clk_orphan_list);
  
  	clk->parent = new_parent;
  }
  
  void __clk_reparent(struct clk *clk, struct clk *new_parent)
  {
  	clk_reparent(clk, new_parent);
  	clk_debug_reparent(clk, new_parent);
  	__clk_recalc_rates(clk, POST_RATE_CHANGE);
  }
  
  static u8 clk_fetch_parent_index(struct clk *clk, struct clk *parent)
  {
  	u8 i;
  
  	if (!clk->parents)
  		clk->parents = kzalloc((sizeof(struct clk*) * clk->num_parents),
  								GFP_KERNEL);
  
  	/*
  	 * find index of new parent clock using cached parent ptrs,
  	 * or if not yet cached, use string name comparison and cache
  	 * them now to avoid future calls to __clk_lookup.
  	 */
  	for (i = 0; i < clk->num_parents; i++) {
  		if (clk->parents && clk->parents[i] == parent)
  			break;
  		else if (!strcmp(clk->parent_names[i], parent->name)) {
  			if (clk->parents)
  				clk->parents[i] = __clk_lookup(parent->name);
  			break;
  		}
  	}
  
  	return i;
  }
  
  static int __clk_set_parent(struct clk *clk, struct clk *parent, u8 p_index)
  {
  	unsigned long flags;
  	int ret = 0;
  	struct clk *old_parent = clk->parent;
  	bool migrated_enable = false;
  
  	/* migrate prepare */
  	if (clk->prepare_count)
  		__clk_prepare(parent);
  
  	flags = clk_enable_lock();
  
  	/* migrate enable */
  	if (clk->enable_count) {
  		__clk_enable(parent);
  		migrated_enable = true;
  	}
  
  	/* update the clk tree topology */
  	clk_reparent(clk, parent);
  
  	clk_enable_unlock(flags);
  
  	/* change clock input source */
  	if (parent && clk->ops->set_parent)
  		ret = clk->ops->set_parent(clk->hw, p_index);
  
  	if (ret) {
  		/*
  		 * The error handling is tricky due to that we need to release
  		 * the spinlock while issuing the .set_parent callback. This
  		 * means the new parent might have been enabled/disabled in
  		 * between, which must be considered when doing rollback.
  		 */
  		flags = clk_enable_lock();
  
  		clk_reparent(clk, old_parent);
  
  		if (migrated_enable && clk->enable_count) {
  			__clk_disable(parent);
  		} else if (migrated_enable && (clk->enable_count == 0)) {
  			__clk_disable(old_parent);
  		} else if (!migrated_enable && clk->enable_count) {
  			__clk_disable(parent);
  			__clk_enable(old_parent);
  		}
  
  		clk_enable_unlock(flags);
  
  		if (clk->prepare_count)
  			__clk_unprepare(parent);
  
  		return ret;
  	}
  
  	/* clean up enable for old parent if migration was done */
  	if (migrated_enable) {
  		flags = clk_enable_lock();
  		__clk_disable(old_parent);
  		clk_enable_unlock(flags);
  	}
  
  	/* clean up prepare for old parent if migration was done */
  	if (clk->prepare_count)
  		__clk_unprepare(old_parent);
  
  	/* update debugfs with new clk tree topology */
  	clk_debug_reparent(clk, parent);
  	return 0;
  }
  
  /**
   * clk_set_parent - switch the parent of a mux clk
   * @clk: the mux clk whose input we are switching
   * @parent: the new input to clk
   *
   * Re-parent clk to use parent as it's new input source.  If clk has the
   * CLK_SET_PARENT_GATE flag set then clk must be gated for this
   * operation to succeed.  After successfully changing clk's parent
   * clk_set_parent will update the clk topology, sysfs topology and
   * propagate rate recalculation via __clk_recalc_rates.  Returns 0 on
   * success, -EERROR otherwise.
   */
  int clk_set_parent(struct clk *clk, struct clk *parent)
  {
  	int ret = 0;
  	u8 p_index = 0;
  	unsigned long p_rate = 0;
  
  	if (!clk || !clk->ops)
  		return -EINVAL;
  
  	/* verify ops for for multi-parent clks */
  	if ((clk->num_parents > 1) && (!clk->ops->set_parent))
  		return -ENOSYS;
  
  	/* prevent racing with updates to the clock topology */
  	clk_prepare_lock();
  
  	if (clk->parent == parent)
  		goto out;
  
  	/* check that we are allowed to re-parent if the clock is in use */
  	if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count) {
  		ret = -EBUSY;
  		goto out;
  	}
  
  	/* try finding the new parent index */
  	if (parent) {
  		p_index = clk_fetch_parent_index(clk, parent);
  		p_rate = parent->rate;
  		if (p_index == clk->num_parents) {
  			pr_debug("%s: clk %s can not be parent of clk %s\n",
  					__func__, parent->name, clk->name);
  			ret = -EINVAL;
  			goto out;
  		}
  	}
  
  	/* propagate PRE_RATE_CHANGE notifications */
  	if (clk->notifier_count)
  		ret = __clk_speculate_rates(clk, p_rate);
  
  	/* abort if a driver objects */
  	if (ret & NOTIFY_STOP_MASK)
  		goto out;
  
  	/* do the re-parent */
  	ret = __clk_set_parent(clk, parent, p_index);
  
  	/* propagate rate recalculation accordingly */
  	if (ret)
  		__clk_recalc_rates(clk, ABORT_RATE_CHANGE);
  	else
  		__clk_recalc_rates(clk, POST_RATE_CHANGE);
  
  out:
  	clk_prepare_unlock();
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(clk_set_parent);
  
  /**
   * __clk_init - initialize the data structures in a struct clk
   * @dev:	device initializing this clk, placeholder for now
   * @clk:	clk being initialized
   *
   * Initializes the lists in struct clk, queries the hardware for the
   * parent and rate and sets them both.
   */
  int __clk_init(struct device *dev, struct clk *clk)
  {
  	int i, ret = 0;
  	struct clk *orphan;
  	struct hlist_node *tmp2;
  
  	if (!clk)
  		return -EINVAL;
  
  	clk_prepare_lock();
  
  	/* check to see if a clock with this name is already registered */
  	if (__clk_lookup(clk->name)) {
  		pr_debug("%s: clk %s already initialized\n",
  				__func__, clk->name);
  		ret = -EEXIST;
  		goto out;
  	}
  
  	/* check that clk_ops are sane.  See Documentation/clk.txt */
  	if (clk->ops->set_rate &&
  			!(clk->ops->round_rate && clk->ops->recalc_rate)) {
  		pr_warning("%s: %s must implement .round_rate & .recalc_rate\n",
  				__func__, clk->name);
  		ret = -EINVAL;
  		goto out;
  	}
  
  	if (clk->ops->set_parent && !clk->ops->get_parent) {
  		pr_warning("%s: %s must implement .get_parent & .set_parent\n",
  				__func__, clk->name);
  		ret = -EINVAL;
  		goto out;
  	}
  
  	/* throw a WARN if any entries in parent_names are NULL */
  	for (i = 0; i < clk->num_parents; i++)
  		WARN(!clk->parent_names[i],
  				"%s: invalid NULL in %s's .parent_names\n",
  				__func__, clk->name);
  
  	/*
  	 * Allocate an array of struct clk *'s to avoid unnecessary string
  	 * look-ups of clk's possible parents.  This can fail for clocks passed
  	 * in to clk_init during early boot; thus any access to clk->parents[]
  	 * must always check for a NULL pointer and try to populate it if
  	 * necessary.
  	 *
  	 * If clk->parents is not NULL we skip this entire block.  This allows
  	 * for clock drivers to statically initialize clk->parents.
  	 */
  	if (clk->num_parents > 1 && !clk->parents) {
  		clk->parents = kzalloc((sizeof(struct clk*) * clk->num_parents),
  				GFP_KERNEL);
  		/*
  		 * __clk_lookup returns NULL for parents that have not been
  		 * clk_init'd; thus any access to clk->parents[] must check
  		 * for a NULL pointer.  We can always perform lazy lookups for
  		 * missing parents later on.
  		 */
  		if (clk->parents)
  			for (i = 0; i < clk->num_parents; i++)
  				clk->parents[i] =
  					__clk_lookup(clk->parent_names[i]);
  	}
  
  	clk->parent = __clk_init_parent(clk);
  
  	/*
  	 * Populate clk->parent if parent has already been __clk_init'd.  If
  	 * parent has not yet been __clk_init'd then place clk in the orphan
  	 * list.  If clk has set the CLK_IS_ROOT flag then place it in the root
  	 * clk list.
  	 *
  	 * Every time a new clk is clk_init'd then we walk the list of orphan
  	 * clocks and re-parent any that are children of the clock currently
  	 * being clk_init'd.
  	 */
  	if (clk->parent)
  		hlist_add_head(&clk->child_node,
  				&clk->parent->children);
  	else if (clk->flags & CLK_IS_ROOT)
  		hlist_add_head(&clk->child_node, &clk_root_list);
  	else
  		hlist_add_head(&clk->child_node, &clk_orphan_list);
  
  	/*
  	 * Set clk's rate.  The preferred method is to use .recalc_rate.  For
  	 * simple clocks and lazy developers the default fallback is to use the
  	 * parent's rate.  If a clock doesn't have a parent (or is orphaned)
  	 * then rate is set to zero.
  	 */
  	if (clk->ops->recalc_rate)
  		clk->rate = clk->ops->recalc_rate(clk->hw,
  				__clk_get_rate(clk->parent));
  	else if (clk->parent)
  		clk->rate = clk->parent->rate;
  	else
  		clk->rate = 0;
  
  	/*
  	 * walk the list of orphan clocks and reparent any that are children of
  	 * this clock
  	 */
  	hlist_for_each_entry_safe(orphan, tmp2, &clk_orphan_list, child_node) {
  		if (orphan->ops->get_parent) {
  			i = orphan->ops->get_parent(orphan->hw);
  			if (!strcmp(clk->name, orphan->parent_names[i]))
  				__clk_reparent(orphan, clk);
  			continue;
  		}
  
  		for (i = 0; i < orphan->num_parents; i++)
  			if (!strcmp(clk->name, orphan->parent_names[i])) {
  				__clk_reparent(orphan, clk);
  				break;
  			}
  	 }
  
  	/*
  	 * optional platform-specific magic
  	 *
  	 * The .init callback is not used by any of the basic clock types, but
  	 * exists for weird hardware that must perform initialization magic.
  	 * Please consider other ways of solving initialization problems before
  	 * using this callback, as it's use is discouraged.
  	 */
  	if (clk->ops->init)
  		clk->ops->init(clk->hw);
  
  	clk_debug_register(clk);
  
  out:
  	clk_prepare_unlock();
  
  	return ret;
  }
  
  /**
   * __clk_register - register a clock and return a cookie.
   *
   * Same as clk_register, except that the .clk field inside hw shall point to a
   * preallocated (generally statically allocated) struct clk. None of the fields
   * of the struct clk need to be initialized.
   *
   * The data pointed to by .init and .clk field shall NOT be marked as init
   * data.
   *
   * __clk_register is only exposed via clk-private.h and is intended for use with
   * very large numbers of clocks that need to be statically initialized.  It is
   * a layering violation to include clk-private.h from any code which implements
   * a clock's .ops; as such any statically initialized clock data MUST be in a
   * separate C file from the logic that implements it's operations.  Returns 0
   * on success, otherwise an error code.
   */
  struct clk *__clk_register(struct device *dev, struct clk_hw *hw)
  {
  	int ret;
  	struct clk *clk;
  
  	clk = hw->clk;
  	clk->name = hw->init->name;
  	clk->ops = hw->init->ops;
  	clk->hw = hw;
  	clk->flags = hw->init->flags;
  	clk->parent_names = hw->init->parent_names;
  	clk->num_parents = hw->init->num_parents;
  
  	ret = __clk_init(dev, clk);
  	if (ret)
  		return ERR_PTR(ret);
  
  	return clk;
  }
  EXPORT_SYMBOL_GPL(__clk_register);
  
  static int _clk_register(struct device *dev, struct clk_hw *hw, struct clk *clk)
  {
  	int i, ret;
  
  	clk->name = kstrdup(hw->init->name, GFP_KERNEL);
  	if (!clk->name) {
  		pr_err("%s: could not allocate clk->name\n", __func__);
  		ret = -ENOMEM;
  		goto fail_name;
  	}
  	clk->ops = hw->init->ops;
  	clk->hw = hw;
  	clk->flags = hw->init->flags;
  	clk->num_parents = hw->init->num_parents;
  	hw->clk = clk;
  
  	/* allocate local copy in case parent_names is __initdata */
  	clk->parent_names = kzalloc((sizeof(char*) * clk->num_parents),
  			GFP_KERNEL);
  
  	if (!clk->parent_names) {
  		pr_err("%s: could not allocate clk->parent_names\n", __func__);
  		ret = -ENOMEM;
  		goto fail_parent_names;
  	}
  
  
  	/* copy each string name in case parent_names is __initdata */
  	for (i = 0; i < clk->num_parents; i++) {
  		clk->parent_names[i] = kstrdup(hw->init->parent_names[i],
  						GFP_KERNEL);
  		if (!clk->parent_names[i]) {
  			pr_err("%s: could not copy parent_names\n", __func__);
  			ret = -ENOMEM;
  			goto fail_parent_names_copy;
  		}
  	}
  
  	ret = __clk_init(dev, clk);
  	if (!ret)
  		return 0;
  
  fail_parent_names_copy:
  	while (--i >= 0)
  		kfree(clk->parent_names[i]);
  	kfree(clk->parent_names);
  fail_parent_names:
  	kfree(clk->name);
  fail_name:
  	return ret;
  }
  
  /**
   * clk_register - allocate a new clock, register it and return an opaque cookie
   * @dev: device that is registering this clock
   * @hw: link to hardware-specific clock data
   *
   * clk_register is the primary interface for populating the clock tree with new
   * clock nodes.  It returns a pointer to the newly allocated struct clk which
   * cannot be dereferenced by driver code but may be used in conjuction with the
   * rest of the clock API.  In the event of an error clk_register will return an
   * error code; drivers must test for an error code after calling clk_register.
   */
  struct clk *clk_register(struct device *dev, struct clk_hw *hw)
  {
  	int ret;
  	struct clk *clk;
  
  	clk = kzalloc(sizeof(*clk), GFP_KERNEL);
  	if (!clk) {
  		pr_err("%s: could not allocate clk\n", __func__);
  		ret = -ENOMEM;
  		goto fail_out;
  	}
  
  	ret = _clk_register(dev, hw, clk);
  	if (!ret)
  		return clk;
  
  	kfree(clk);
  fail_out:
  	return ERR_PTR(ret);
  }
  EXPORT_SYMBOL_GPL(clk_register);
  
  /**
   * clk_unregister - unregister a currently registered clock
   * @clk: clock to unregister
   *
   * Currently unimplemented.
   */
  void clk_unregister(struct clk *clk) {}
  EXPORT_SYMBOL_GPL(clk_unregister);
  
  static void devm_clk_release(struct device *dev, void *res)
  {
  	clk_unregister(res);
  }
  
  /**
   * devm_clk_register - resource managed clk_register()
   * @dev: device that is registering this clock
   * @hw: link to hardware-specific clock data
   *
   * Managed clk_register(). Clocks returned from this function are
   * automatically clk_unregister()ed on driver detach. See clk_register() for
   * more information.
   */
  struct clk *devm_clk_register(struct device *dev, struct clk_hw *hw)
  {
  	struct clk *clk;
  	int ret;
  
  	clk = devres_alloc(devm_clk_release, sizeof(*clk), GFP_KERNEL);
  	if (!clk)
  		return ERR_PTR(-ENOMEM);
  
  	ret = _clk_register(dev, hw, clk);
  	if (!ret) {
  		devres_add(dev, clk);
  	} else {
  		devres_free(clk);
  		clk = ERR_PTR(ret);
  	}
  
  	return clk;
  }
  EXPORT_SYMBOL_GPL(devm_clk_register);
  
  static int devm_clk_match(struct device *dev, void *res, void *data)
  {
  	struct clk *c = res;
  	if (WARN_ON(!c))
  		return 0;
  	return c == data;
  }
  
  /**
   * devm_clk_unregister - resource managed clk_unregister()
   * @clk: clock to unregister
   *
   * Deallocate a clock allocated with devm_clk_register(). Normally
   * this function will not need to be called and the resource management
   * code will ensure that the resource is freed.
   */
  void devm_clk_unregister(struct device *dev, struct clk *clk)
  {
  	WARN_ON(devres_release(dev, devm_clk_release, devm_clk_match, clk));
  }
  EXPORT_SYMBOL_GPL(devm_clk_unregister);
  
  /***        clk rate change notifiers        ***/
  
  /**
   * clk_notifier_register - add a clk rate change notifier
   * @clk: struct clk * to watch
   * @nb: struct notifier_block * with callback info
   *
   * Request notification when clk's rate changes.  This uses an SRCU
   * notifier because we want it to block and notifier unregistrations are
   * uncommon.  The callbacks associated with the notifier must not
   * re-enter into the clk framework by calling any top-level clk APIs;
   * this will cause a nested prepare_lock mutex.
   *
   * Pre-change notifier callbacks will be passed the current, pre-change
   * rate of the clk via struct clk_notifier_data.old_rate.  The new,
   * post-change rate of the clk is passed via struct
   * clk_notifier_data.new_rate.
   *
   * Post-change notifiers will pass the now-current, post-change rate of
   * the clk in both struct clk_notifier_data.old_rate and struct
   * clk_notifier_data.new_rate.
   *
   * Abort-change notifiers are effectively the opposite of pre-change
   * notifiers: the original pre-change clk rate is passed in via struct
   * clk_notifier_data.new_rate and the failed post-change rate is passed
   * in via struct clk_notifier_data.old_rate.
   *
   * clk_notifier_register() must be called from non-atomic context.
   * Returns -EINVAL if called with null arguments, -ENOMEM upon
   * allocation failure; otherwise, passes along the return value of
   * srcu_notifier_chain_register().
   */
  int clk_notifier_register(struct clk *clk, struct notifier_block *nb)
  {
  	struct clk_notifier *cn;
  	int ret = -ENOMEM;
  
  	if (!clk || !nb)
  		return -EINVAL;
  
  	clk_prepare_lock();
  
  	/* search the list of notifiers for this clk */
  	list_for_each_entry(cn, &clk_notifier_list, node)
  		if (cn->clk == clk)
  			break;
  
  	/* if clk wasn't in the notifier list, allocate new clk_notifier */
  	if (cn->clk != clk) {
  		cn = kzalloc(sizeof(struct clk_notifier), GFP_KERNEL);
  		if (!cn)
  			goto out;
  
  		cn->clk = clk;
  		srcu_init_notifier_head(&cn->notifier_head);
  
  		list_add(&cn->node, &clk_notifier_list);
  	}
  
  	ret = srcu_notifier_chain_register(&cn->notifier_head, nb);
  
  	clk->notifier_count++;
  
  out:
  	clk_prepare_unlock();
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(clk_notifier_register);
  
  /**
   * clk_notifier_unregister - remove a clk rate change notifier
   * @clk: struct clk *
   * @nb: struct notifier_block * with callback info
   *
   * Request no further notification for changes to 'clk' and frees memory
   * allocated in clk_notifier_register.
   *
   * Returns -EINVAL if called with null arguments; otherwise, passes
   * along the return value of srcu_notifier_chain_unregister().
   */
  int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb)
  {
  	struct clk_notifier *cn = NULL;
  	int ret = -EINVAL;
  
  	if (!clk || !nb)
  		return -EINVAL;
  
  	clk_prepare_lock();
  
  	list_for_each_entry(cn, &clk_notifier_list, node)
  		if (cn->clk == clk)
  			break;
  
  	if (cn->clk == clk) {
  		ret = srcu_notifier_chain_unregister(&cn->notifier_head, nb);
  
  		clk->notifier_count--;
  
  		/* XXX the notifier code should handle this better */
  		if (!cn->notifier_head.head) {
  			srcu_cleanup_notifier_head(&cn->notifier_head);
  			list_del(&cn->node);
  			kfree(cn);
  		}
  
  	} else {
  		ret = -ENOENT;
  	}
  
  	clk_prepare_unlock();
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(clk_notifier_unregister);
  
  #ifdef CONFIG_OF
  /**
   * struct of_clk_provider - Clock provider registration structure
   * @link: Entry in global list of clock providers
   * @node: Pointer to device tree node of clock provider
   * @get: Get clock callback.  Returns NULL or a struct clk for the
   *       given clock specifier
   * @data: context pointer to be passed into @get callback
   */
  struct of_clk_provider {
  	struct list_head link;
  
  	struct device_node *node;
  	struct clk *(*get)(struct of_phandle_args *clkspec, void *data);
  	void *data;
  };
  
  extern struct of_device_id __clk_of_table[];
  
  static const struct of_device_id __clk_of_table_sentinel
  	__used __section(__clk_of_table_end);
  
  static LIST_HEAD(of_clk_providers);
  static DEFINE_MUTEX(of_clk_lock);
  
  struct clk *of_clk_src_simple_get(struct of_phandle_args *clkspec,
  				     void *data)
  {
  	return data;
  }
  EXPORT_SYMBOL_GPL(of_clk_src_simple_get);
  
  struct clk *of_clk_src_onecell_get(struct of_phandle_args *clkspec, void *data)
  {
  	struct clk_onecell_data *clk_data = data;
  	unsigned int idx = clkspec->args[0];
  
  	if (idx >= clk_data->clk_num) {
  		pr_err("%s: invalid clock index %d\n", __func__, idx);
  		return ERR_PTR(-EINVAL);
  	}
  
  	return clk_data->clks[idx];
  }
  EXPORT_SYMBOL_GPL(of_clk_src_onecell_get);
  
  /**
   * of_clk_add_provider() - Register a clock provider for a node
   * @np: Device node pointer associated with clock provider
   * @clk_src_get: callback for decoding clock
   * @data: context pointer for @clk_src_get callback.
   */
  int of_clk_add_provider(struct device_node *np,
  			struct clk *(*clk_src_get)(struct of_phandle_args *clkspec,
  						   void *data),
  			void *data)
  {
  	struct of_clk_provider *cp;
  
  	cp = kzalloc(sizeof(struct of_clk_provider), GFP_KERNEL);
  	if (!cp)
  		return -ENOMEM;
  
  	cp->node = of_node_get(np);
  	cp->data = data;
  	cp->get = clk_src_get;
  
  	mutex_lock(&of_clk_lock);
  	list_add(&cp->link, &of_clk_providers);
  	mutex_unlock(&of_clk_lock);
  	pr_debug("Added clock from %s\n", np->full_name);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(of_clk_add_provider);
  
  /**
   * of_clk_del_provider() - Remove a previously registered clock provider
   * @np: Device node pointer associated with clock provider
   */
  void of_clk_del_provider(struct device_node *np)
  {
  	struct of_clk_provider *cp;
  
  	mutex_lock(&of_clk_lock);
  	list_for_each_entry(cp, &of_clk_providers, link) {
  		if (cp->node == np) {
  			list_del(&cp->link);
  			of_node_put(cp->node);
  			kfree(cp);
  			break;
  		}
  	}
  	mutex_unlock(&of_clk_lock);
  }
  EXPORT_SYMBOL_GPL(of_clk_del_provider);
  
  struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
  {
  	struct of_clk_provider *provider;
  	struct clk *clk = ERR_PTR(-ENOENT);
  
  	/* Check if we have such a provider in our array */
  	mutex_lock(&of_clk_lock);
  	list_for_each_entry(provider, &of_clk_providers, link) {
  		if (provider->node == clkspec->np)
  			clk = provider->get(clkspec, provider->data);
  		if (!IS_ERR(clk))
  			break;
  	}
  	mutex_unlock(&of_clk_lock);
  
  	return clk;
  }
  
  int of_clk_get_parent_count(struct device_node *np)
  {
  	return of_count_phandle_with_args(np, "clocks", "#clock-cells");
  }
  EXPORT_SYMBOL_GPL(of_clk_get_parent_count);
  
  const char *of_clk_get_parent_name(struct device_node *np, int index)
  {
  	struct of_phandle_args clkspec;
  	const char *clk_name;
  	int rc;
  
  	if (index < 0)
  		return NULL;
  
  	rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
  					&clkspec);
  	if (rc)
  		return NULL;
  
  	if (of_property_read_string_index(clkspec.np, "clock-output-names",
  					  clkspec.args_count ? clkspec.args[0] : 0,
  					  &clk_name) < 0)
  		clk_name = clkspec.np->name;
  
  	of_node_put(clkspec.np);
  	return clk_name;
  }
  EXPORT_SYMBOL_GPL(of_clk_get_parent_name);
  
  /**
   * of_clk_init() - Scan and init clock providers from the DT
   * @matches: array of compatible values and init functions for providers.
   *
   * This function scans the device tree for matching clock providers and
   * calls their initialization functions
   */
  void __init of_clk_init(const struct of_device_id *matches)
  {
  	struct device_node *np;
  
  	if (!matches)
  		matches = __clk_of_table;
  	pr_debug("[%s][%d]match-name:%s\n", __func__, __LINE__, matches->name);
  	for_each_matching_node(np, matches) {
  		const struct of_device_id *match = of_match_node(matches, np);
  		of_clk_init_cb_t clk_init_cb = match->data;
  		pr_debug("[%s][%d]match-name:%s\n", __func__, __LINE__, matches->name);
  		clk_init_cb(np);
  	}
  }
  #endif
  