/* * Copyright (C) 2010-2011 Canonical Ltd * Copyright (C) 2011-2012 Linaro Ltd * * 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 #include #include #include #include #include #include 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 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 #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); #endif /*** 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 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 */ 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);