1 files changed, 1461 insertions, 0 deletions

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
new file mode 100644
index 000000000000..9cf6f59e3e19
--- /dev/null
+++ b/drivers/clk/clk.c
@@ -0,0 +1,1461 @@
+/*
+ * 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>
+
+static DEFINE_SPINLOCK(enable_lock);
+static DEFINE_MUTEX(prepare_lock);
+
+static HLIST_HEAD(clk_root_list);
+static HLIST_HEAD(clk_orphan_list);
+static LIST_HEAD(clk_notifier_list);
+
+/***        debugfs support        ***/
+
+#ifdef CONFIG_COMMON_CLK_DEBUG
+#include <linux/debugfs.h>
+
+static struct dentry *rootdir;
+static struct dentry *orphandir;
+static int inited = 0;
+
+/* 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;
+        struct hlist_node *tmp;
+        int ret = -EINVAL;;
+
+        if (!clk || !pdentry)
+                goto out;
+
+        ret = clk_debug_create_one(clk, pdentry);
+
+        if (ret)
+                goto out;
+
+        hlist_for_each_entry(child, tmp, &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_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 hlist_node *tmp;
+
+        rootdir = debugfs_create_dir("clk", NULL);
+
+        if (!rootdir)
+                return -ENOMEM;
+
+        orphandir = debugfs_create_dir("orphans", rootdir);
+
+        if (!orphandir)
+                return -ENOMEM;
+
+        mutex_lock(&prepare_lock);
+
+        hlist_for_each_entry(clk, tmp, &clk_root_list, child_node)
+                clk_debug_create_subtree(clk, rootdir);
+
+        hlist_for_each_entry(clk, tmp, &clk_orphan_list, child_node)
+                clk_debug_create_subtree(clk, orphandir);
+
+        inited = 1;
+
+        mutex_unlock(&prepare_lock);
+
+        return 0;
+}
+late_initcall(clk_debug_init);
+#else
+static inline int clk_debug_register(struct clk *clk) { return 0; }
+#endif /* CONFIG_COMMON_CLK_DEBUG */
+
+#ifdef CONFIG_COMMON_CLK_DISABLE_UNUSED
+/* caller must hold prepare_lock */
+static void clk_disable_unused_subtree(struct clk *clk)
+{
+        struct clk *child;
+        struct hlist_node *tmp;
+        unsigned long flags;
+
+        if (!clk)
+                goto out;
+
+        hlist_for_each_entry(child, tmp, &clk->children, child_node)
+                clk_disable_unused_subtree(child);
+
+        spin_lock_irqsave(&enable_lock, flags);
+
+        if (clk->enable_count)
+                goto unlock_out;
+
+        if (clk->flags & CLK_IGNORE_UNUSED)
+                goto unlock_out;
+
+        if (__clk_is_enabled(clk) && clk->ops->disable)
+                clk->ops->disable(clk->hw);
+
+unlock_out:
+        spin_unlock_irqrestore(&enable_lock, flags);
+
+out:
+        return;
+}
+
+static int clk_disable_unused(void)
+{
+        struct clk *clk;
+        struct hlist_node *tmp;
+
+        mutex_lock(&prepare_lock);
+
+        hlist_for_each_entry(clk, tmp, &clk_root_list, child_node)
+                clk_disable_unused_subtree(clk);
+
+        hlist_for_each_entry(clk, tmp, &clk_orphan_list, child_node)
+                clk_disable_unused_subtree(clk);
+
+        mutex_unlock(&prepare_lock);
+
+        return 0;
+}
+late_initcall(clk_disable_unused);
+#else
+static inline int clk_disable_unused(struct clk *clk) { return 0; }
+#endif /* CONFIG_COMMON_CLK_DISABLE_UNUSED */
+
+/***    helper functions   ***/
+
+inline const char *__clk_get_name(struct clk *clk)
+{
+        return !clk ? NULL : clk->name;
+}
+
+inline struct clk_hw *__clk_get_hw(struct clk *clk)
+{
+        return !clk ? NULL : clk->hw;
+}
+
+inline u8 __clk_get_num_parents(struct clk *clk)
+{
+        return !clk ? -EINVAL : clk->num_parents;
+}
+
+inline struct clk *__clk_get_parent(struct clk *clk)
+{
+        return !clk ? NULL : clk->parent;
+}
+
+inline int __clk_get_enable_count(struct clk *clk)
+{
+        return !clk ? -EINVAL : clk->enable_count;
+}
+
+inline int __clk_get_prepare_count(struct clk *clk)
+{
+        return !clk ? -EINVAL : clk->prepare_count;
+}
+
+unsigned long __clk_get_rate(struct clk *clk)
+{
+        unsigned long ret;
+
+        if (!clk) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        ret = clk->rate;
+
+        if (clk->flags & CLK_IS_ROOT)
+                goto out;
+
+        if (!clk->parent)
+                ret = -ENODEV;
+
+out:
+        return ret;
+}
+
+inline unsigned long __clk_get_flags(struct clk *clk)
+{
+        return !clk ? -EINVAL : clk->flags;
+}
+
+int __clk_is_enabled(struct clk *clk)
+{
+        int ret;
+
+        if (!clk)
+                return -EINVAL;
+
+        /*
+         * .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;
+        struct hlist_node *tmp;
+
+        if (!strcmp(clk->name, name))
+                return clk;
+
+        hlist_for_each_entry(child, tmp, &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;
+        struct hlist_node *tmp;
+
+        if (!name)
+                return NULL;
+
+        /* search the 'proper' clk tree first */
+        hlist_for_each_entry(root_clk, tmp, &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, tmp, &clk_orphan_list, child_node) {
+                ret = __clk_lookup_subtree(name, root_clk);
+                if (ret)
+                        return ret;
+        }
+
+        return NULL;
+}
+
+/***        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)
+{
+        mutex_lock(&prepare_lock);
+        __clk_unprepare(clk);
+        mutex_unlock(&prepare_lock);
+}
+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;
+
+        mutex_lock(&prepare_lock);
+        ret = __clk_prepare(clk);
+        mutex_unlock(&prepare_lock);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(clk_prepare);
+
+static void __clk_disable(struct clk *clk)
+{
+        if (!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;
+
+        spin_lock_irqsave(&enable_lock, flags);
+        __clk_disable(clk);
+        spin_unlock_irqrestore(&enable_lock, 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;
+
+        spin_lock_irqsave(&enable_lock, flags);
+        ret = __clk_enable(clk);
+        spin_unlock_irqrestore(&enable_lock, flags);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(clk_enable);
+
+/**
+ * clk_get_rate - return the rate of clk
+ * @clk: the clk whose rate is being returned
+ *
+ * Simply returns the cached rate of the clk.  Does not query the hardware.  If
+ * clk is NULL then returns -EINVAL.
+ */
+unsigned long clk_get_rate(struct clk *clk)
+{
+        unsigned long rate;
+
+        mutex_lock(&prepare_lock);
+        rate = __clk_get_rate(clk);
+        mutex_unlock(&prepare_lock);
+
+        return rate;
+}
+EXPORT_SYMBOL_GPL(clk_get_rate);
+
+/**
+ * __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 unused;
+
+        if (!clk)
+                return -EINVAL;
+
+        if (!clk->ops->round_rate)
+                return clk->rate;
+
+        if (clk->flags & CLK_SET_RATE_PARENT)
+                return clk->ops->round_rate(clk->hw, rate, &unused);
+        else
+                return clk->ops->round_rate(clk->hw, rate, NULL);
+}
+
+/**
+ * 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;
+
+        mutex_lock(&prepare_lock);
+        ret = __clk_round_rate(clk, rate);
+        mutex_unlock(&prepare_lock);
+
+        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 hlist_node *tmp;
+        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, tmp, &clk->children, child_node)
+                __clk_recalc_rates(child, msg);
+}
+
+/**
+ * __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 hlist_node *tmp;
+        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 the rate change if a driver returns NOTIFY_BAD */
+        if (clk->notifier_count)
+                ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate);
+
+        if (ret == NOTIFY_BAD)
+                goto out;
+
+        hlist_for_each_entry(child, tmp, &clk->children, child_node) {
+                ret = __clk_speculate_rates(child, new_rate);
+                if (ret == NOTIFY_BAD)
+                        break;
+        }
+
+out:
+        return ret;
+}
+
+static void clk_calc_subtree(struct clk *clk, unsigned long new_rate)
+{
+        struct clk *child;
+        struct hlist_node *tmp;
+
+        clk->new_rate = new_rate;
+
+        hlist_for_each_entry(child, tmp, &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 = clk->parent->rate;
+        unsigned long new_rate;
+
+        if (!clk->ops->round_rate && !(clk->flags & CLK_SET_RATE_PARENT)) {
+                clk->new_rate = clk->rate;
+                return NULL;
+        }
+
+        if (!clk->ops->round_rate && (clk->flags & CLK_SET_RATE_PARENT)) {
+                top = clk_calc_new_rates(clk->parent, rate);
+                new_rate = clk->new_rate = clk->parent->new_rate;
+
+                goto out;
+        }
+
+        if (clk->flags & CLK_SET_RATE_PARENT)
+                new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
+        else
+                new_rate = clk->ops->round_rate(clk->hw, rate, NULL);
+
+        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 hlist_node *tmp;
+        struct clk *child, *fail_clk = NULL;
+        int ret = NOTIFY_DONE;
+
+        if (clk->rate == clk->new_rate)
+                return 0;
+
+        if (clk->notifier_count) {
+                ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
+                if (ret == NOTIFY_BAD)
+                        fail_clk = clk;
+        }
+
+        hlist_for_each_entry(child, tmp, &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;
+        struct hlist_node *tmp;
+
+        old_rate = clk->rate;
+
+        if (clk->ops->set_rate)
+                clk->ops->set_rate(clk->hw, clk->new_rate);
+
+        if (clk->ops->recalc_rate)
+                clk->rate = clk->ops->recalc_rate(clk->hw,
+                                clk->parent->rate);
+        else
+                clk->rate = clk->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, tmp, &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 change the rate of clk.
+ *
+ * If clk has the CLK_SET_RATE_GATE flag set and it is enabled this call
+ * will fail; only when the clk is disabled will it be able to change
+ * its rate.
+ *
+ * Setting the CLK_SET_RATE_PARENT flag allows clk_set_rate to
+ * recursively 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 0 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.  If there is a failure during upstream
+ * propagation then clk_set_rate will unwind and restore each clk's rate
+ * that had been successfully changed.  Afterwards a rate change abort
+ * notification will be propagated downstream, starting from the clk
+ * that failed.
+ *
+ * At the end of all of the rate setting, clk_set_rate internally calls
+ * __clk_recalc_rates and propagates the rate changes downstream,
+ * starting from the highest clk whose rate was changed.  This has the
+ * added benefit of propagating post-rate change notifiers.
+ *
+ * Note that while post-rate change and rate change abort notifications
+ * are guaranteed to be sent to a clk only once per call to
+ * clk_set_rate, pre-change notifications will be sent for every clk
+ * whose rate is changed.  Stacking pre-change notifications is noisy
+ * for the drivers subscribed to them, but this allows drivers to react
+ * to intermediate clk rate changes up until the point where the final
+ * rate is achieved at the end of upstream propagation.
+ *
+ * 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 */
+        mutex_lock(&prepare_lock);
+
+        /* bail early if nothing to do */
+        if (rate == clk->rate)
+                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);
+
+        mutex_unlock(&prepare_lock);
+
+        return 0;
+out:
+        mutex_unlock(&prepare_lock);
+
+        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;
+
+        mutex_lock(&prepare_lock);
+        parent = __clk_get_parent(clk);
+        mutex_unlock(&prepare_lock);
+
+        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 =
+                        kmalloc((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;
+}
+
+void __clk_reparent(struct clk *clk, struct clk *new_parent)
+{
+#ifdef CONFIG_COMMON_CLK_DEBUG
+        struct dentry *d;
+        struct dentry *new_parent_d;
+#endif
+
+        if (!clk || !new_parent)
+                return;
+
+        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);
+
+#ifdef CONFIG_COMMON_CLK_DEBUG
+        if (!inited)
+                goto out;
+
+        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);
+out:
+#endif
+
+        clk->parent = new_parent;
+
+        __clk_recalc_rates(clk, POST_RATE_CHANGE);
+}
+
+static int __clk_set_parent(struct clk *clk, struct clk *parent)
+{
+        struct clk *old_parent;
+        unsigned long flags;
+        int ret = -EINVAL;
+        u8 i;
+
+        old_parent = clk->parent;
+
+        /* find index of new parent clock using cached parent ptrs */
+        for (i = 0; i < clk->num_parents; i++)
+                if (clk->parents[i] == parent)
+                        break;
+
+        /*
+         * find index of new parent clock using string name comparison
+         * also try to cache the parent to avoid future calls to __clk_lookup
+         */
+        if (i == clk->num_parents)
+                for (i = 0; i < clk->num_parents; i++)
+                        if (!strcmp(clk->parent_names[i], parent->name)) {
+                                clk->parents[i] = __clk_lookup(parent->name);
+                                break;
+                        }
+
+        if (i == clk->num_parents) {
+                pr_debug("%s: clock %s is not a possible parent of clock %s\n",
+                                __func__, parent->name, clk->name);
+                goto out;
+        }
+
+        /* migrate prepare and enable */
+        if (clk->prepare_count)
+                __clk_prepare(parent);
+
+        /* FIXME replace with clk_is_enabled(clk) someday */
+        spin_lock_irqsave(&enable_lock, flags);
+        if (clk->enable_count)
+                __clk_enable(parent);
+        spin_unlock_irqrestore(&enable_lock, flags);
+
+        /* change clock input source */
+        ret = clk->ops->set_parent(clk->hw, i);
+
+        /* clean up old prepare and enable */
+        spin_lock_irqsave(&enable_lock, flags);
+        if (clk->enable_count)
+                __clk_disable(old_parent);
+        spin_unlock_irqrestore(&enable_lock, flags);
+
+        if (clk->prepare_count)
+                __clk_unprepare(old_parent);
+
+out:
+        return ret;
+}
+
+/**
+ * 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;
+
+        if (!clk || !clk->ops)
+                return -EINVAL;
+
+        if (!clk->ops->set_parent)
+                return -ENOSYS;
+
+        /* prevent racing with updates to the clock topology */
+        mutex_lock(&prepare_lock);
+
+        if (clk->parent == parent)
+                goto out;
+
+        /* propagate PRE_RATE_CHANGE notifications */
+        if (clk->notifier_count)
+                ret = __clk_speculate_rates(clk, parent->rate);
+
+        /* abort if a driver objects */
+        if (ret == NOTIFY_STOP)
+                goto out;
+
+        /* only re-parent if the clock is not in use */
+        if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count)
+                ret = -EBUSY;
+        else
+                ret = __clk_set_parent(clk, parent);
+
+        /* propagate ABORT_RATE_CHANGE if .set_parent failed */
+        if (ret) {
+                __clk_recalc_rates(clk, ABORT_RATE_CHANGE);
+                goto out;
+        }
+
+        /* propagate rate recalculation downstream */
+        __clk_reparent(clk, parent);
+
+out:
+        mutex_unlock(&prepare_lock);
+
+        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.
+ *
+ * Any struct clk passed into __clk_init must have the following members
+ * populated:
+ *      .name
+ *      .ops
+ *      .hw
+ *      .parent_names
+ *      .num_parents
+ *      .flags
+ *
+ * Essentially, everything that would normally be passed into clk_register is
+ * assumed to be initialized already in __clk_init.  The other members may be
+ * populated, but are optional.
+ *
+ * __clk_init 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.
+ */
+void __clk_init(struct device *dev, struct clk *clk)
+{
+        int i;
+        struct clk *orphan;
+        struct hlist_node *tmp, *tmp2;
+
+        if (!clk)
+                return;
+
+        mutex_lock(&prepare_lock);
+
+        /* check to see if a clock with this name is already registered */
+        if (__clk_lookup(clk->name))
+                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 && !clk->parents) {
+                clk->parents = kmalloc((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, tmp, tmp2, &clk_orphan_list, child_node)
+                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:
+        mutex_unlock(&prepare_lock);
+
+        return;
+}
+
+/**
+ * clk_register - allocate a new clock, register it and return an opaque cookie
+ * @dev: device that is registering this clock
+ * @name: clock name
+ * @ops: operations this clock supports
+ * @hw: link to hardware-specific clock data
+ * @parent_names: array of string names for all possible parents
+ * @num_parents: number of possible parents
+ * @flags: framework-level hints and quirks
+ *
+ * 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.
+ */
+struct clk *clk_register(struct device *dev, const char *name,
+                const struct clk_ops *ops, struct clk_hw *hw,
+                char **parent_names, u8 num_parents, unsigned long flags)
+{
+        struct clk *clk;
+
+        clk = kzalloc(sizeof(*clk), GFP_KERNEL);
+        if (!clk)
+                return NULL;
+
+        clk->name = name;
+        clk->ops = ops;
+        clk->hw = hw;
+        clk->flags = flags;
+        clk->parent_names = parent_names;
+        clk->num_parents = num_parents;
+        hw->clk = clk;
+
+        __clk_init(dev, clk);
+
+        return clk;
+}
+EXPORT_SYMBOL_GPL(clk_register);
+
+/***        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;
+
+        mutex_lock(&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:
+        mutex_unlock(&prepare_lock);
+
+        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;
+
+        mutex_lock(&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);
+                        kfree(cn);
+                }
+
+        } else {
+                ret = -ENOENT;
+        }
+
+        mutex_unlock(&prepare_lock);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(clk_notifier_unregister);