/* * 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 #include #include #include #include #include #include "clk.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); static long clk_core_get_accuracy(struct clk_core *clk); static unsigned long clk_core_get_rate(struct clk_core *clk); static int clk_core_get_phase(struct clk_core *clk); static bool clk_core_is_prepared(struct clk_core *clk); static bool clk_core_is_enabled(struct clk_core *clk); static struct clk_core *clk_core_lookup(const char *name); /*** private data structures ***/ struct clk_core { const char *name; const struct clk_ops *ops; struct clk_hw *hw; struct module *owner; struct clk_core *parent; const char **parent_names; struct clk_core **parents; u8 num_parents; u8 new_parent_index; unsigned long rate; unsigned long req_rate; unsigned long new_rate; struct clk_core *new_parent; struct clk_core *new_child; unsigned long flags; unsigned int enable_count; unsigned int prepare_count; unsigned long accuracy; int phase; struct hlist_head children; struct hlist_node child_node; struct hlist_node debug_node; struct hlist_head clks; unsigned int notifier_count; #ifdef CONFIG_DEBUG_FS struct dentry *dentry; #endif struct kref ref; }; struct clk { struct clk_core *core; const char *dev_id; const char *con_id; unsigned long min_rate; unsigned long max_rate; struct hlist_node child_node; }; /*** 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_DEBUG_FS #include static struct dentry *rootdir; static int inited = 0; static DEFINE_MUTEX(clk_debug_lock); static HLIST_HEAD(clk_debug_list); static struct hlist_head *all_lists[] = { &clk_root_list, &clk_orphan_list, NULL, }; static struct hlist_head *orphan_list[] = { &clk_orphan_list, NULL, }; static void clk_summary_show_one(struct seq_file *s, struct clk_core *c, int level) { if (!c) return; seq_printf(s, "%*s%-*s %11d %12d %11lu %10lu %-3d\n", level * 3 + 1, "", 30 - level * 3, c->name, c->enable_count, c->prepare_count, clk_core_get_rate(c), clk_core_get_accuracy(c), clk_core_get_phase(c)); } static void clk_summary_show_subtree(struct seq_file *s, struct clk_core *c, int level) { struct clk_core *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_core *c; struct hlist_head **lists = (struct hlist_head **)s->private; seq_puts(s, " clock enable_cnt prepare_cnt rate accuracy phase\n"); seq_puts(s, "----------------------------------------------------------------------------------------\n"); clk_prepare_lock(); for (; *lists; lists++) hlist_for_each_entry(c, *lists, 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_core *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", clk_core_get_rate(c)); seq_printf(s, "\"accuracy\": %lu", clk_core_get_accuracy(c)); seq_printf(s, "\"phase\": %d", clk_core_get_phase(c)); } static void clk_dump_subtree(struct seq_file *s, struct clk_core *c, int level) { struct clk_core *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_core *c; bool first_node = true; struct hlist_head **lists = (struct hlist_head **)s->private; seq_printf(s, "{"); clk_prepare_lock(); for (; *lists; lists++) { hlist_for_each_entry(c, *lists, child_node) { if (!first_node) seq_puts(s, ","); first_node = false; 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, }; static int clk_debug_create_one(struct clk_core *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_u32("clk_accuracy", S_IRUGO, clk->dentry, (u32 *)&clk->accuracy); if (!d) goto err_out; d = debugfs_create_u32("clk_phase", S_IRUGO, clk->dentry, (u32 *)&clk->phase); 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; if (clk->ops->debug_init) { ret = clk->ops->debug_init(clk->hw, clk->dentry); if (ret) goto err_out; } ret = 0; goto out; err_out: debugfs_remove_recursive(clk->dentry); clk->dentry = NULL; 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. */ static int clk_debug_register(struct clk_core *clk) { int ret = 0; mutex_lock(&clk_debug_lock); hlist_add_head(&clk->debug_node, &clk_debug_list); if (!inited) goto unlock; ret = clk_debug_create_one(clk, rootdir); unlock: mutex_unlock(&clk_debug_lock); return ret; } /** * clk_debug_unregister - remove a clk node from the debugfs clk tree * @clk: the clk being removed from the debugfs clk tree * * Dynamically removes a clk and all it's children clk nodes from the * debugfs clk tree if clk->dentry points to debugfs created by * clk_debug_register in __clk_init. */ static void clk_debug_unregister(struct clk_core *clk) { mutex_lock(&clk_debug_lock); hlist_del_init(&clk->debug_node); debugfs_remove_recursive(clk->dentry); clk->dentry = NULL; mutex_unlock(&clk_debug_lock); } struct dentry *clk_debugfs_add_file(struct clk_hw *hw, char *name, umode_t mode, void *data, const struct file_operations *fops) { struct dentry *d = NULL; if (hw->core->dentry) d = debugfs_create_file(name, mode, hw->core->dentry, data, fops); return d; } EXPORT_SYMBOL_GPL(clk_debugfs_add_file); /** * 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_core *clk; struct dentry *d; rootdir = debugfs_create_dir("clk", NULL); if (!rootdir) return -ENOMEM; d = debugfs_create_file("clk_summary", S_IRUGO, rootdir, &all_lists, &clk_summary_fops); if (!d) return -ENOMEM; d = debugfs_create_file("clk_dump", S_IRUGO, rootdir, &all_lists, &clk_dump_fops); if (!d) return -ENOMEM; d = debugfs_create_file("clk_orphan_summary", S_IRUGO, rootdir, &orphan_list, &clk_summary_fops); if (!d) return -ENOMEM; d = debugfs_create_file("clk_orphan_dump", S_IRUGO, rootdir, &orphan_list, &clk_dump_fops); if (!d) return -ENOMEM; mutex_lock(&clk_debug_lock); hlist_for_each_entry(clk, &clk_debug_list, debug_node) clk_debug_create_one(clk, rootdir); inited = 1; mutex_unlock(&clk_debug_lock); return 0; } late_initcall(clk_debug_init); #else static inline int clk_debug_register(struct clk_core *clk) { return 0; } static inline void clk_debug_reparent(struct clk_core *clk, struct clk_core *new_parent) { } static inline void clk_debug_unregister(struct clk_core *clk) { } #endif /* caller must hold prepare_lock */ static void clk_unprepare_unused_subtree(struct clk_core *clk) { struct clk_core *child; 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_core_is_prepared(clk)) { if (clk->ops->unprepare_unused) clk->ops->unprepare_unused(clk->hw); else if (clk->ops->unprepare) clk->ops->unprepare(clk->hw); } } /* caller must hold prepare_lock */ static void clk_disable_unused_subtree(struct clk_core *clk) { struct clk_core *child; unsigned long flags; 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_core_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); } 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_core *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_sync(clk_disable_unused); /*** helper functions ***/ const char *__clk_get_name(struct clk *clk) { return !clk ? NULL : clk->core->name; } EXPORT_SYMBOL_GPL(__clk_get_name); struct clk_hw *__clk_get_hw(struct clk *clk) { return !clk ? NULL : clk->core->hw; } EXPORT_SYMBOL_GPL(__clk_get_hw); u8 __clk_get_num_parents(struct clk *clk) { return !clk ? 0 : clk->core->num_parents; } EXPORT_SYMBOL_GPL(__clk_get_num_parents); struct clk *__clk_get_parent(struct clk *clk) { if (!clk) return NULL; /* TODO: Create a per-user clk and change callers to call clk_put */ return !clk->core->parent ? NULL : clk->core->parent->hw->clk; } EXPORT_SYMBOL_GPL(__clk_get_parent); static struct clk_core *clk_core_get_parent_by_index(struct clk_core *clk, u8 index) { if (!clk || index >= clk->num_parents) return NULL; else if (!clk->parents) return clk_core_lookup(clk->parent_names[index]); else if (!clk->parents[index]) return clk->parents[index] = clk_core_lookup(clk->parent_names[index]); else return clk->parents[index]; } struct clk *clk_get_parent_by_index(struct clk *clk, u8 index) { struct clk_core *parent; if (!clk) return NULL; parent = clk_core_get_parent_by_index(clk->core, index); return !parent ? NULL : parent->hw->clk; } EXPORT_SYMBOL_GPL(clk_get_parent_by_index); unsigned int __clk_get_enable_count(struct clk *clk) { return !clk ? 0 : clk->core->enable_count; } static unsigned long clk_core_get_rate_nolock(struct clk_core *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_rate(struct clk *clk) { if (!clk) return 0; return clk_core_get_rate_nolock(clk->core); } EXPORT_SYMBOL_GPL(__clk_get_rate); static unsigned long __clk_get_accuracy(struct clk_core *clk) { if (!clk) return 0; return clk->accuracy; } unsigned long __clk_get_flags(struct clk *clk) { return !clk ? 0 : clk->core->flags; } EXPORT_SYMBOL_GPL(__clk_get_flags); static bool clk_core_is_prepared(struct clk_core *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_prepared(struct clk *clk) { if (!clk) return false; return clk_core_is_prepared(clk->core); } static bool clk_core_is_enabled(struct clk_core *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; } bool __clk_is_enabled(struct clk *clk) { if (!clk) return false; return clk_core_is_enabled(clk->core); } EXPORT_SYMBOL_GPL(__clk_is_enabled); static struct clk_core *__clk_lookup_subtree(const char *name, struct clk_core *clk) { struct clk_core *child; struct clk_core *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; } static struct clk_core *clk_core_lookup(const char *name) { struct clk_core *root_clk; struct clk_core *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; } static bool mux_is_better_rate(unsigned long rate, unsigned long now, unsigned long best, unsigned long flags) { if (flags & CLK_MUX_ROUND_CLOSEST) return abs(now - rate) < abs(best - rate); return now <= rate && now > best; } static long clk_mux_determine_rate_flags(struct clk_hw *hw, unsigned long rate, unsigned long min_rate, unsigned long max_rate, unsigned long *best_parent_rate, struct clk_hw **best_parent_p, unsigned long flags) { struct clk_core *core = hw->core, *parent, *best_parent = NULL; int i, num_parents; unsigned long parent_rate, best = 0; /* if NO_REPARENT flag set, pass through to current parent */ if (core->flags & CLK_SET_RATE_NO_REPARENT) { parent = core->parent; if (core->flags & CLK_SET_RATE_PARENT) best = __clk_determine_rate(parent ? parent->hw : NULL, rate, min_rate, max_rate); else if (parent) best = clk_core_get_rate_nolock(parent); else best = clk_core_get_rate_nolock(core); goto out; } /* find the parent that can provide the fastest rate <= rate */ num_parents = core->num_parents; for (i = 0; i < num_parents; i++) { parent = clk_core_get_parent_by_index(core, i); if (!parent) continue; if (core->flags & CLK_SET_RATE_PARENT) parent_rate = __clk_determine_rate(parent->hw, rate, min_rate, max_rate); else parent_rate = clk_core_get_rate_nolock(parent); if (mux_is_better_rate(rate, parent_rate, best, flags)) { best_parent = parent; best = parent_rate; } } out: if (best_parent) *best_parent_p = best_parent->hw; *best_parent_rate = best; return best; } struct clk *__clk_lookup(const char *name) { struct clk_core *core = clk_core_lookup(name); return !core ? NULL : core->hw->clk; } static void clk_core_get_boundaries(struct clk_core *clk, unsigned long *min_rate, unsigned long *max_rate) { struct clk *clk_user; *min_rate = 0; *max_rate = ULONG_MAX; hlist_for_each_entry(clk_user, &clk->clks, child_node) *min_rate = max(*min_rate, clk_user->min_rate); hlist_for_each_entry(clk_user, &clk->clks, child_node) *max_rate = min(*max_rate, clk_user->max_rate); } /* * Helper for finding best parent to provide a given frequency. This can be used * directly as a determine_rate callback (e.g. for a mux), or from a more * complex clock that may combine a mux with other operations. */ long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate, unsigned long min_rate, unsigned long max_rate, unsigned long *best_parent_rate, struct clk_hw **best_parent_p) { return clk_mux_determine_rate_flags(hw, rate, min_rate, max_rate, best_parent_rate, best_parent_p, 0); } EXPORT_SYMBOL_GPL(__clk_mux_determine_rate); long __clk_mux_determine_rate_closest(struct clk_hw *hw, unsigned long rate, unsigned long min_rate, unsigned long max_rate, unsigned long *best_parent_rate, struct clk_hw **best_parent_p) { return clk_mux_determine_rate_flags(hw, rate, min_rate, max_rate, best_parent_rate, best_parent_p, CLK_MUX_ROUND_CLOSEST); } EXPORT_SYMBOL_GPL(__clk_mux_determine_rate_closest); /*** clk api ***/ static void clk_core_unprepare(struct clk_core *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_core_unprepare(clk->parent); } /** * clk_unprepare - undo preparation of a clock source * @clk: the clk being unprepared * * 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) { if (IS_ERR_OR_NULL(clk)) return; clk_prepare_lock(); clk_core_unprepare(clk->core); clk_prepare_unlock(); } EXPORT_SYMBOL_GPL(clk_unprepare); static int clk_core_prepare(struct clk_core *clk) { int ret = 0; if (!clk) return 0; if (clk->prepare_count == 0) { ret = clk_core_prepare(clk->parent); if (ret) return ret; if (clk->ops->prepare) { ret = clk->ops->prepare(clk->hw); if (ret) { clk_core_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; if (!clk) return 0; clk_prepare_lock(); ret = clk_core_prepare(clk->core); clk_prepare_unlock(); return ret; } EXPORT_SYMBOL_GPL(clk_prepare); static void clk_core_disable(struct clk_core *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_core_disable(clk->parent); } static void __clk_disable(struct clk *clk) { if (!clk) return; clk_core_disable(clk->core); } /** * 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; if (IS_ERR_OR_NULL(clk)) return; flags = clk_enable_lock(); __clk_disable(clk); clk_enable_unlock(flags); } EXPORT_SYMBOL_GPL(clk_disable); static int clk_core_enable(struct clk_core *clk) { int ret = 0; if (!clk) return 0; if (WARN_ON(clk->prepare_count == 0)) return -ESHUTDOWN; if (clk->enable_count == 0) { ret = clk_core_enable(clk->parent); if (ret) return ret; if (clk->ops->enable) { ret = clk->ops->enable(clk->hw); if (ret) { clk_core_disable(clk->parent); return ret; } } } clk->enable_count++; return 0; } static int __clk_enable(struct clk *clk) { if (!clk) return 0; return clk_core_enable(clk->core); } /** * 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); static unsigned long clk_core_round_rate_nolock(struct clk_core *clk, unsigned long rate, unsigned long min_rate, unsigned long max_rate) { unsigned long parent_rate = 0; struct clk_core *parent; struct clk_hw *parent_hw; if (!clk) return 0; parent = clk->parent; if (parent) parent_rate = parent->rate; if (clk->ops->determine_rate) { parent_hw = parent ? parent->hw : NULL; return clk->ops->determine_rate(clk->hw, rate, min_rate, max_rate, &parent_rate, &parent_hw); } else if (clk->ops->round_rate) return clk->ops->round_rate(clk->hw, rate, &parent_rate); else if (clk->flags & CLK_SET_RATE_PARENT) return clk_core_round_rate_nolock(clk->parent, rate, min_rate, max_rate); else return clk->rate; } /** * __clk_determine_rate - get the closest rate actually supported by a clock * @hw: determine the rate of this clock * @rate: target rate * @min_rate: returned rate must be greater than this rate * @max_rate: returned rate must be less than this rate * * Caller must hold prepare_lock. Useful for clk_ops such as .set_rate and * .determine_rate. */ unsigned long __clk_determine_rate(struct clk_hw *hw, unsigned long rate, unsigned long min_rate, unsigned long max_rate) { if (!hw) return 0; return clk_core_round_rate_nolock(hw->core, rate, min_rate, max_rate); } EXPORT_SYMBOL_GPL(__clk_determine_rate); /** * __clk_round_rate - round the given rate for a clk * @clk: round the rate of this clock * @rate: the rate which is to be rounded * * 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 min_rate; unsigned long max_rate; if (!clk) return 0; clk_core_get_boundaries(clk->core, &min_rate, &max_rate); return clk_core_round_rate_nolock(clk->core, rate, min_rate, max_rate); } EXPORT_SYMBOL_GPL(__clk_round_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; if (!clk) return 0; 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_core *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.old_rate = old_rate; cnd.new_rate = new_rate; list_for_each_entry(cn, &clk_notifier_list, node) { if (cn->clk->core == clk) { cnd.clk = cn->clk; ret = srcu_notifier_call_chain(&cn->notifier_head, msg, &cnd); } } return ret; } /** * __clk_recalc_accuracies * @clk: first clk in the subtree * * Walks the subtree of clks starting with clk and recalculates accuracies as * it goes. Note that if a clk does not implement the .recalc_accuracy * callback then it is assumed that the clock will take on the accuracy of it's * parent. * * Caller must hold prepare_lock. */ static void __clk_recalc_accuracies(struct clk_core *clk) { unsigned long parent_accuracy = 0; struct clk_core *child; if (clk->parent) parent_accuracy = clk->parent->accuracy; if (clk->ops->recalc_accuracy) clk->accuracy = clk->ops->recalc_accuracy(clk->hw, parent_accuracy); else clk->accuracy = parent_accuracy; hlist_for_each_entry(child, &clk->children, child_node) __clk_recalc_accuracies(child); } static long clk_core_get_accuracy(struct clk_core *clk) { unsigned long accuracy; clk_prepare_lock(); if (clk && (clk->flags & CLK_GET_ACCURACY_NOCACHE)) __clk_recalc_accuracies(clk); accuracy = __clk_get_accuracy(clk); clk_prepare_unlock(); return accuracy; } /** * clk_get_accuracy - return the accuracy of clk * @clk: the clk whose accuracy is being returned * * Simply returns the cached accuracy of the clk, unless * CLK_GET_ACCURACY_NOCACHE flag is set, which means a recalc_rate will be * issued. * If clk is NULL then returns 0. */ long clk_get_accuracy(struct clk *clk) { if (!clk) return 0; return clk_core_get_accuracy(clk->core); } EXPORT_SYMBOL_GPL(clk_get_accuracy); static unsigned long clk_recalc(struct clk_core *clk, unsigned long parent_rate) { if (clk->ops->recalc_rate) return clk->ops->recalc_rate(clk->hw, parent_rate); return parent_rate; } /** * __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 its 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_core *clk, unsigned long msg) { unsigned long old_rate; unsigned long parent_rate = 0; struct clk_core *child; old_rate = clk->rate; if (clk->parent) parent_rate = clk->parent->rate; clk->rate = clk_recalc(clk, 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); } static unsigned long clk_core_get_rate(struct clk_core *clk) { unsigned long rate; clk_prepare_lock(); if (clk && (clk->flags & CLK_GET_RATE_NOCACHE)) __clk_recalc_rates(clk, 0); rate = clk_core_get_rate_nolock(clk); clk_prepare_unlock(); return rate; } EXPORT_SYMBOL_GPL(clk_core_get_rate); /** * 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) { if (!clk) return 0; return clk_core_get_rate(clk->core); } EXPORT_SYMBOL_GPL(clk_get_rate); static int clk_fetch_parent_index(struct clk_core *clk, struct clk_core *parent) { int i; if (!clk->parents) { clk->parents = kcalloc(clk->num_parents, sizeof(struct clk *), GFP_KERNEL); if (!clk->parents) return -ENOMEM; } /* * 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_core_lookup. */ for (i = 0; i < clk->num_parents; i++) { if (clk->parents[i] == parent) return i; if (clk->parents[i]) continue; if (!strcmp(clk->parent_names[i], parent->name)) { clk->parents[i] = clk_core_lookup(parent->name); return i; } } return -EINVAL; } static void clk_reparent(struct clk_core *clk, struct clk_core *new_parent) { hlist_del(&clk->child_node); if (new_parent) { /* avoid duplicate POST_RATE_CHANGE notifications */ if (new_parent->new_child == clk) new_parent->new_child = NULL; hlist_add_head(&clk->child_node, &new_parent->children); } else { hlist_add_head(&clk->child_node, &clk_orphan_list); } clk->parent = new_parent; } static struct clk_core *__clk_set_parent_before(struct clk_core *clk, struct clk_core *parent) { unsigned long flags; struct clk_core *old_parent = clk->parent; /* * Migrate prepare state between parents and prevent race with * clk_enable(). * * If the clock is not prepared, then a race with * clk_enable/disable() is impossible since we already have the * prepare lock (future calls to clk_enable() need to be preceded by * a clk_prepare()). * * If the clock is prepared, migrate the prepared state to the new * parent and also protect against a race with clk_enable() by * forcing the clock and the new parent on. This ensures that all * future calls to clk_enable() are practically NOPs with respect to * hardware and software states. * * See also: Comment for clk_set_parent() below. */ if (clk->prepare_count) { clk_core_prepare(parent); clk_core_enable(parent); clk_core_enable(clk); } /* update the clk tree topology */ flags = clk_enable_lock(); clk_reparent(clk, parent); clk_enable_unlock(flags); return old_parent; } static void __clk_set_parent_after(struct clk_core *core, struct clk_core *parent, struct clk_core *old_parent) { /* * Finish the migration of prepare state and undo the changes done * for preventing a race with clk_enable(). */ if (core->prepare_count) { clk_core_disable(core); clk_core_disable(old_parent); clk_core_unprepare(old_parent); } } static int __clk_set_parent(struct clk_core *clk, struct clk_core *parent, u8 p_index) { unsigned long flags; int ret = 0; struct clk_core *old_parent; old_parent = __clk_set_parent_before(clk, parent); /* change clock input source */ if (parent && clk->ops->set_parent) ret = clk->ops->set_parent(clk->hw, p_index); if (ret) { flags = clk_enable_lock(); clk_reparent(clk, old_parent); clk_enable_unlock(flags); if (clk->prepare_count) { clk_core_disable(clk); clk_core_disable(parent); clk_core_unprepare(parent); } return ret; } __clk_set_parent_after(clk, parent, old_parent); return 0; } /** * __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 its parent. * * Caller must hold prepare_lock. */ static int __clk_speculate_rates(struct clk_core *clk, unsigned long parent_rate) { struct clk_core *child; unsigned long new_rate; int ret = NOTIFY_DONE; new_rate = clk_recalc(clk, 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) { pr_debug("%s: clk notifier callback for clock %s aborted with error %d\n", __func__, clk->name, ret); 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_core *clk, unsigned long new_rate, struct clk_core *new_parent, u8 p_index) { struct clk_core *child; clk->new_rate = new_rate; clk->new_parent = new_parent; clk->new_parent_index = p_index; /* include clk in new parent's PRE_RATE_CHANGE notifications */ clk->new_child = NULL; if (new_parent && new_parent != clk->parent) new_parent->new_child = clk; hlist_for_each_entry(child, &clk->children, child_node) { child->new_rate = clk_recalc(child, new_rate); clk_calc_subtree(child, child->new_rate, NULL, 0); } } /* * calculate the new rates returning the topmost clock that has to be * changed. */ static struct clk_core *clk_calc_new_rates(struct clk_core *clk, unsigned long rate) { struct clk_core *top = clk; struct clk_core *old_parent, *parent; struct clk_hw *parent_hw; unsigned long best_parent_rate = 0; unsigned long new_rate; unsigned long min_rate; unsigned long max_rate; int p_index = 0; /* sanity */ if (IS_ERR_OR_NULL(clk)) return NULL; /* save parent rate, if it exists */ parent = old_parent = clk->parent; if (parent) best_parent_rate = parent->rate; clk_core_get_boundaries(clk, &min_rate, &max_rate); /* find the closest rate and parent clk/rate */ if (clk->ops->determine_rate) { parent_hw = parent ? parent->hw : NULL; new_rate = clk->ops->determine_rate(clk->hw, rate, min_rate, max_rate, &best_parent_rate, &parent_hw); parent = parent_hw ? parent_hw->core : NULL; } else if (clk->ops->round_rate) { new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate); if (new_rate < min_rate || new_rate > max_rate) return NULL; } else if (!parent || !(clk->flags & CLK_SET_RATE_PARENT)) { /* pass-through clock without adjustable parent */ clk->new_rate = clk->rate; return NULL; } else { /* pass-through clock with adjustable parent */ top = clk_calc_new_rates(parent, rate); new_rate = parent->new_rate; goto out; } /* some clocks must be gated to change parent */ if (parent != old_parent && (clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count) { pr_debug("%s: %s not gated but wants to reparent\n", __func__, clk->name); return NULL; } /* try finding the new parent index */ if (parent && clk->num_parents > 1) { p_index = clk_fetch_parent_index(clk, parent); if (p_index < 0) { pr_debug("%s: clk %s can not be parent of clk %s\n", __func__, parent->name, clk->name); return NULL; } } if ((clk->flags & CLK_SET_RATE_PARENT) && parent && best_parent_rate != parent->rate) top = clk_calc_new_rates(parent, best_parent_rate); out: clk_calc_subtree(clk, new_rate, parent, p_index); 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_core *clk_propagate_rate_change(struct clk_core *clk, unsigned long event) { struct clk_core *child, *tmp_clk, *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) { /* Skip children who will be reparented to another clock */ if (child->new_parent && child->new_parent != clk) continue; tmp_clk = clk_propagate_rate_change(child, event); if (tmp_clk) fail_clk = tmp_clk; } /* handle the new child who might not be in clk->children yet */ if (clk->new_child) { tmp_clk = clk_propagate_rate_change(clk->new_child, event); if (tmp_clk) fail_clk = tmp_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_core *clk) { struct clk_core *child; struct hlist_node *tmp; unsigned long old_rate; unsigned long best_parent_rate = 0; bool skip_set_rate = false; struct clk_core *old_parent; old_rate = clk->rate; if (clk->new_parent) best_parent_rate = clk->new_parent->rate; else if (clk->parent) best_parent_rate = clk->parent->rate; if (clk->new_parent && clk->new_parent != clk->parent) { old_parent = __clk_set_parent_before(clk, clk->new_parent); if (clk->ops->set_rate_and_parent) { skip_set_rate = true; clk->ops->set_rate_and_parent(clk->hw, clk->new_rate, best_parent_rate, clk->new_parent_index); } else if (clk->ops->set_parent) { clk->ops->set_parent(clk->hw, clk->new_parent_index); } __clk_set_parent_after(clk, clk->new_parent, old_parent); } if (!skip_set_rate && clk->ops->set_rate) clk->ops->set_rate(clk->hw, clk->new_rate, best_parent_rate); clk->rate = clk_recalc(clk, best_parent_rate); if (clk->notifier_count && old_rate != clk->rate) __clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate); /* * Use safe iteration, as change_rate can actually swap parents * for certain clock types. */ hlist_for_each_entry_safe(child, tmp, &clk->children, child_node) { /* Skip children who will be reparented to another clock */ if (child->new_parent && child->new_parent != clk) continue; clk_change_rate(child); } /* handle the new child who might not be in clk->children yet */ if (clk->new_child) clk_change_rate(clk->new_child); } static int clk_core_set_rate_nolock(struct clk_core *clk, unsigned long req_rate) { struct clk_core *top, *fail_clk; unsigned long rate = req_rate; int ret = 0; if (!clk) return 0; /* bail early if nothing to do */ if (rate == clk_core_get_rate_nolock(clk)) return 0; if ((clk->flags & CLK_SET_RATE_GATE) && clk->prepare_count) return -EBUSY; /* calculate new rates and get the topmost changed clock */ top = clk_calc_new_rates(clk, rate); if (!top) return -EINVAL; /* notify that we are about to change rates */ fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE); if (fail_clk) { pr_debug("%s: failed to set %s rate\n", __func__, fail_clk->name); clk_propagate_rate_change(top, ABORT_RATE_CHANGE); return -EBUSY; } /* change the rates */ clk_change_rate(top); clk->req_rate = req_rate; return ret; } /** * 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 its 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) { int ret; if (!clk) return 0; /* prevent racing with updates to the clock topology */ clk_prepare_lock(); ret = clk_core_set_rate_nolock(clk->core, rate); clk_prepare_unlock(); return ret; } EXPORT_SYMBOL_GPL(clk_set_rate); /** * clk_set_rate_range - set a rate range for a clock source * @clk: clock source * @min: desired minimum clock rate in Hz, inclusive * @max: desired maximum clock rate in Hz, inclusive * * Returns success (0) or negative errno. */ int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max) { int ret = 0; if (!clk) return 0; if (min > max) { pr_err("%s: clk %s dev %s con %s: invalid range [%lu, %lu]\n", __func__, clk->core->name, clk->dev_id, clk->con_id, min, max); return -EINVAL; } clk_prepare_lock(); if (min != clk->min_rate || max != clk->max_rate) { clk->min_rate = min; clk->max_rate = max; ret = clk_core_set_rate_nolock(clk->core, clk->core->req_rate); } clk_prepare_unlock(); return ret; } EXPORT_SYMBOL_GPL(clk_set_rate_range); /** * clk_set_min_rate - set a minimum clock rate for a clock source * @clk: clock source * @rate: desired minimum clock rate in Hz, inclusive * * Returns success (0) or negative errno. */ int clk_set_min_rate(struct clk *clk, unsigned long rate) { if (!clk) return 0; return clk_set_rate_range(clk, rate, clk->max_rate); } EXPORT_SYMBOL_GPL(clk_set_min_rate); /** * clk_set_max_rate - set a maximum clock rate for a clock source * @clk: clock source * @rate: desired maximum clock rate in Hz, inclusive * * Returns success (0) or negative errno. */ int clk_set_max_rate(struct clk *clk, unsigned long rate) { if (!clk) return 0; return clk_set_rate_range(clk, clk->min_rate, rate); } EXPORT_SYMBOL_GPL(clk_set_max_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. */ static struct clk_core *__clk_init_parent(struct clk_core *clk) { struct clk_core *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)) clk->parent = clk_core_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 lookups. 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 = kcalloc(clk->num_parents, sizeof(struct clk *), GFP_KERNEL); ret = clk_core_get_parent_by_index(clk, index); out: return ret; } static void clk_core_reparent(struct clk_core *clk, struct clk_core *new_parent) { clk_reparent(clk, new_parent); __clk_recalc_accuracies(clk); __clk_recalc_rates(clk, POST_RATE_CHANGE); } /** * clk_has_parent - check if a clock is a possible parent for another * @clk: clock source * @parent: parent clock source * * This function can be used in drivers that need to check that a clock can be * the parent of another without actually changing the parent. * * Returns true if @parent is a possible parent for @clk, false otherwise. */ bool clk_has_parent(struct clk *clk, struct clk *parent) { struct clk_core *core, *parent_core; unsigned int i; /* NULL clocks should be nops, so return success if either is NULL. */ if (!clk || !parent) return true; core = clk->core; parent_core = parent->core; /* Optimize for the case where the parent is already the parent. */ if (core->parent == parent_core) return true; for (i = 0; i < core->num_parents; i++) if (strcmp(core->parent_names[i], parent_core->name) == 0) return true; return false; } EXPORT_SYMBOL_GPL(clk_has_parent); static int clk_core_set_parent(struct clk_core *clk, struct clk_core *parent) { int ret = 0; int p_index = 0; unsigned long p_rate = 0; if (!clk) return 0; /* 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 < 0) { pr_debug("%s: clk %s can not be parent of clk %s\n", __func__, parent->name, clk->name); ret = p_index; goto out; } } /* propagate PRE_RATE_CHANGE notifications */ 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 an accuracy recalculation accordingly */ if (ret) { __clk_recalc_rates(clk, ABORT_RATE_CHANGE); } else { __clk_recalc_rates(clk, POST_RATE_CHANGE); __clk_recalc_accuracies(clk); } out: clk_prepare_unlock(); 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 its new input source. If clk is in * prepared state, the clk will get enabled for the duration of this call. If * that's not acceptable for a specific clk (Eg: the consumer can't handle * that, the reparenting is glitchy in hardware, etc), use the * CLK_SET_PARENT_GATE flag to allow reparenting only when clk is unprepared. * * 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) { if (!clk) return 0; return clk_core_set_parent(clk->core, parent ? parent->core : NULL); } EXPORT_SYMBOL_GPL(clk_set_parent); /** * clk_set_phase - adjust the phase shift of a clock signal * @clk: clock signal source * @degrees: number of degrees the signal is shifted * * Shifts the phase of a clock signal by the specified * degrees. Returns 0 on success, -EERROR otherwise. * * This function makes no distinction about the input or reference * signal that we adjust the clock signal phase against. For example * phase locked-loop clock signal generators we may shift phase with * respect to feedback clock signal input, but for other cases the * clock phase may be shifted with respect to some other, unspecified * signal. * * Additionally the concept of phase shift does not propagate through * the clock tree hierarchy, which sets it apart from clock rates and * clock accuracy. A parent clock phase attribute does not have an * impact on the phase attribute of a child clock. */ int clk_set_phase(struct clk *clk, int degrees) { int ret = 0; if (!clk) goto out; /* sanity check degrees */ degrees %= 360; if (degrees < 0) degrees += 360; clk_prepare_lock(); if (!clk->core->ops->set_phase) goto out_unlock; ret = clk->core->ops->set_phase(clk->core->hw, degrees); if (!ret) clk->core->phase = degrees; out_unlock: clk_prepare_unlock(); out: return ret; } EXPORT_SYMBOL_GPL(clk_set_phase); static int clk_core_get_phase(struct clk_core *clk) { int ret = 0; if (!clk) goto out; clk_prepare_lock(); ret = clk->phase; clk_prepare_unlock(); out: return ret; } EXPORT_SYMBOL_GPL(clk_get_phase); /** * clk_get_phase - return the phase shift of a clock signal * @clk: clock signal source * * Returns the phase shift of a clock node in degrees, otherwise returns * -EERROR. */ int clk_get_phase(struct clk *clk) { if (!clk) return 0; return clk_core_get_phase(clk->core); } /** * __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_core, queries the hardware for the * parent and rate and sets them both. */ static int __clk_init(struct device *dev, struct clk *clk_user) { int i, ret = 0; struct clk_core *orphan; struct hlist_node *tmp2; struct clk_core *clk; unsigned long rate; if (!clk_user) return -EINVAL; clk = clk_user->core; clk_prepare_lock(); /* check to see if a clock with this name is already registered */ if (clk_core_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->determine_rate) && clk->ops->recalc_rate)) { pr_warning("%s: %s must implement .round_rate or .determine_rate in addition to .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; } if (clk->ops->set_rate_and_parent && !(clk->ops->set_parent && clk->ops->set_rate)) { pr_warn("%s: %s must implement .set_parent & .set_rate\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 = kcalloc(clk->num_parents, sizeof(struct clk *), GFP_KERNEL); /* * clk_core_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_core_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 accuracy. The preferred method is to use * .recalc_accuracy. For simple clocks and lazy developers the default * fallback is to use the parent's accuracy. If a clock doesn't have a * parent (or is orphaned) then accuracy is set to zero (perfect * clock). */ if (clk->ops->recalc_accuracy) clk->accuracy = clk->ops->recalc_accuracy(clk->hw, __clk_get_accuracy(clk->parent)); else if (clk->parent) clk->accuracy = clk->parent->accuracy; else clk->accuracy = 0; /* * Set clk's phase. * Since a phase is by definition relative to its parent, just * query the current clock phase, or just assume it's in phase. */ if (clk->ops->get_phase) clk->phase = clk->ops->get_phase(clk->hw); else clk->phase = 0; /* * 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) rate = clk->ops->recalc_rate(clk->hw, clk_core_get_rate_nolock(clk->parent)); else if (clk->parent) rate = clk->parent->rate; else rate = 0; clk->rate = clk->req_rate = rate; /* * 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->num_parents && orphan->ops->get_parent) { i = orphan->ops->get_parent(orphan->hw); if (!strcmp(clk->name, orphan->parent_names[i])) clk_core_reparent(orphan, clk); continue; } for (i = 0; i < orphan->num_parents; i++) if (!strcmp(clk->name, orphan->parent_names[i])) { clk_core_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 its use is discouraged. */ if (clk->ops->init) clk->ops->init(clk->hw); kref_init(&clk->ref); out: clk_prepare_unlock(); if (!ret) clk_debug_register(clk); return ret; } struct clk *__clk_create_clk(struct clk_hw *hw, const char *dev_id, const char *con_id) { struct clk *clk; /* This is to allow this function to be chained to others */ if (!hw || IS_ERR(hw)) return (struct clk *) hw; clk = kzalloc(sizeof(*clk), GFP_KERNEL); if (!clk) return ERR_PTR(-ENOMEM); clk->core = hw->core; clk->dev_id = dev_id; clk->con_id = con_id; clk->max_rate = ULONG_MAX; clk_prepare_lock(); hlist_add_head(&clk->child_node, &hw->core->clks); clk_prepare_unlock(); return clk; } void __clk_free_clk(struct clk *clk) { clk_prepare_lock(); hlist_del(&clk->child_node); clk_prepare_unlock(); kfree(clk); } /** * 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 i, ret; struct clk_core *clk; clk = kzalloc(sizeof(*clk), GFP_KERNEL); if (!clk) { pr_err("%s: could not allocate clk\n", __func__); ret = -ENOMEM; goto fail_out; } clk->name = kstrdup_const(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; if (dev && dev->driver) clk->owner = dev->driver->owner; clk->hw = hw; clk->flags = hw->init->flags; clk->num_parents = hw->init->num_parents; hw->core = clk; /* allocate local copy in case parent_names is __initdata */ clk->parent_names = kcalloc(clk->num_parents, sizeof(char *), 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_const(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; } } INIT_HLIST_HEAD(&clk->clks); hw->clk = __clk_create_clk(hw, NULL, NULL); if (IS_ERR(hw->clk)) { pr_err("%s: could not allocate per-user clk\n", __func__); ret = PTR_ERR(hw->clk); goto fail_parent_names_copy; } ret = __clk_init(dev, hw->clk); if (!ret) return hw->clk; __clk_free_clk(hw->clk); hw->clk = NULL; fail_parent_names_copy: while (--i >= 0) kfree_const(clk->parent_names[i]); kfree(clk->parent_names); fail_parent_names: kfree_const(clk->name); fail_name: kfree(clk); fail_out: return ERR_PTR(ret); } EXPORT_SYMBOL_GPL(clk_register); /* * Free memory allocated for a clock. * Caller must hold prepare_lock. */ static void __clk_release(struct kref *ref) { struct clk_core *clk = container_of(ref, struct clk_core, ref); int i = clk->num_parents; kfree(clk->parents); while (--i >= 0) kfree_const(clk->parent_names[i]); kfree(clk->parent_names); kfree_const(clk->name); kfree(clk); } /* * Empty clk_ops for unregistered clocks. These are used temporarily * after clk_unregister() was called on a clock and until last clock * consumer calls clk_put() and the struct clk object is freed. */ static int clk_nodrv_prepare_enable(struct clk_hw *hw) { return -ENXIO; } static void clk_nodrv_disable_unprepare(struct clk_hw *hw) { WARN_ON_ONCE(1); } static int clk_nodrv_set_rate(struct clk_hw *hw, unsigned long rate, unsigned long parent_rate) { return -ENXIO; } static int clk_nodrv_set_parent(struct clk_hw *hw, u8 index) { return -ENXIO; } static const struct clk_ops clk_nodrv_ops = { .enable = clk_nodrv_prepare_enable, .disable = clk_nodrv_disable_unprepare, .prepare = clk_nodrv_prepare_enable, .unprepare = clk_nodrv_disable_unprepare, .set_rate = clk_nodrv_set_rate, .set_parent = clk_nodrv_set_parent, }; /** * clk_unregister - unregister a currently registered clock * @clk: clock to unregister */ void clk_unregister(struct clk *clk) { unsigned long flags; if (!clk || WARN_ON_ONCE(IS_ERR(clk))) return; clk_debug_unregister(clk->core); clk_prepare_lock(); if (clk->core->ops == &clk_nodrv_ops) { pr_err("%s: unregistered clock: %s\n", __func__, clk->core->name); return; } /* * Assign empty clock ops for consumers that might still hold * a reference to this clock. */ flags = clk_enable_lock(); clk->core->ops = &clk_nodrv_ops; clk_enable_unlock(flags); if (!hlist_empty(&clk->core->children)) { struct clk_core *child; struct hlist_node *t; /* Reparent all children to the orphan list. */ hlist_for_each_entry_safe(child, t, &clk->core->children, child_node) clk_core_set_parent(child, NULL); } hlist_del_init(&clk->core->child_node); if (clk->core->prepare_count) pr_warn("%s: unregistering prepared clock: %s\n", __func__, clk->core->name); kref_put(&clk->core->ref, __clk_release); clk_prepare_unlock(); } EXPORT_SYMBOL_GPL(clk_unregister); static void devm_clk_release(struct device *dev, void *res) { clk_unregister(*(struct clk **)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; struct clk **clkp; clkp = devres_alloc(devm_clk_release, sizeof(*clkp), GFP_KERNEL); if (!clkp) return ERR_PTR(-ENOMEM); clk = clk_register(dev, hw); if (!IS_ERR(clk)) { *clkp = clk; devres_add(dev, clkp); } else { devres_free(clkp); } 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); /* * clkdev helpers */ int __clk_get(struct clk *clk) { struct clk_core *core = !clk ? NULL : clk->core; if (core) { if (!try_module_get(core->owner)) return 0; kref_get(&core->ref); } return 1; } void __clk_put(struct clk *clk) { struct module *owner; if (!clk || WARN_ON_ONCE(IS_ERR(clk))) return; clk_prepare_lock(); hlist_del(&clk->child_node); if (clk->min_rate > clk->core->req_rate || clk->max_rate < clk->core->req_rate) clk_core_set_rate_nolock(clk->core, clk->core->req_rate); owner = clk->core->owner; kref_put(&clk->core->ref, __clk_release); clk_prepare_unlock(); module_put(owner); kfree(clk); } /*** 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. * * In all notification cases cases (pre, post and abort rate change) the * original clock rate is passed to the callback via struct * clk_notifier_data.old_rate and the new frequency is passed via struct * clk_notifier_data.new_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->core->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->core->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; }; 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_mutex); /* of_clk_provider list locking helpers */ void of_clk_lock(void) { mutex_lock(&of_clk_mutex); } void of_clk_unlock(void) { mutex_unlock(&of_clk_mutex); } 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; int ret; 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_mutex); list_add(&cp->link, &of_clk_providers); mutex_unlock(&of_clk_mutex); pr_debug("Added clock from %s\n", np->full_name); ret = of_clk_set_defaults(np, true); if (ret < 0) of_clk_del_provider(np); return ret; } 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_mutex); 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_mutex); } EXPORT_SYMBOL_GPL(of_clk_del_provider); struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec, const char *dev_id, const char *con_id) { struct of_clk_provider *provider; struct clk *clk = ERR_PTR(-EPROBE_DEFER); /* Check if we have such a provider in our array */ list_for_each_entry(provider, &of_clk_providers, link) { if (provider->node == clkspec->np) clk = provider->get(clkspec, provider->data); if (!IS_ERR(clk)) { clk = __clk_create_clk(__clk_get_hw(clk), dev_id, con_id); if (!IS_ERR(clk) && !__clk_get(clk)) { __clk_free_clk(clk); clk = ERR_PTR(-ENOENT); } break; } } return clk; } struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec) { struct clk *clk; mutex_lock(&of_clk_mutex); clk = __of_clk_get_from_provider(clkspec, NULL, __func__); mutex_unlock(&of_clk_mutex); 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; struct property *prop; const char *clk_name; const __be32 *vp; u32 pv; int rc; int count; if (index < 0) return NULL; rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index, &clkspec); if (rc) return NULL; index = clkspec.args_count ? clkspec.args[0] : 0; count = 0; /* if there is an indices property, use it to transfer the index * specified into an array offset for the clock-output-names property. */ of_property_for_each_u32(clkspec.np, "clock-indices", prop, vp, pv) { if (index == pv) { index = count; break; } count++; } if (of_property_read_string_index(clkspec.np, "clock-output-names", index, &clk_name) < 0) clk_name = clkspec.np->name; of_node_put(clkspec.np); return clk_name; } EXPORT_SYMBOL_GPL(of_clk_get_parent_name); struct clock_provider { of_clk_init_cb_t clk_init_cb; struct device_node *np; struct list_head node; }; static LIST_HEAD(clk_provider_list); /* * This function looks for a parent clock. If there is one, then it * checks that the provider for this parent clock was initialized, in * this case the parent clock will be ready. */ static int parent_ready(struct device_node *np) { int i = 0; while (true) { struct clk *clk = of_clk_get(np, i); /* this parent is ready we can check the next one */ if (!IS_ERR(clk)) { clk_put(clk); i++; continue; } /* at least one parent is not ready, we exit now */ if (PTR_ERR(clk) == -EPROBE_DEFER) return 0; /* * Here we make assumption that the device tree is * written correctly. So an error means that there is * no more parent. As we didn't exit yet, then the * previous parent are ready. If there is no clock * parent, no need to wait for them, then we can * consider their absence as being ready */ return 1; } } /** * 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. It also does it by trying * to follow the dependencies. */ void __init of_clk_init(const struct of_device_id *matches) { const struct of_device_id *match; struct device_node *np; struct clock_provider *clk_provider, *next; bool is_init_done; bool force = false; if (!matches) matches = &__clk_of_table; /* First prepare the list of the clocks providers */ for_each_matching_node_and_match(np, matches, &match) { struct clock_provider *parent = kzalloc(sizeof(struct clock_provider), GFP_KERNEL); parent->clk_init_cb = match->data; parent->np = np; list_add_tail(&parent->node, &clk_provider_list); } while (!list_empty(&clk_provider_list)) { is_init_done = false; list_for_each_entry_safe(clk_provider, next, &clk_provider_list, node) { if (force || parent_ready(clk_provider->np)) { clk_provider->clk_init_cb(clk_provider->np); of_clk_set_defaults(clk_provider->np, true); list_del(&clk_provider->node); kfree(clk_provider); is_init_done = true; } } /* * We didn't manage to initialize any of the * remaining providers during the last loop, so now we * initialize all the remaining ones unconditionally * in case the clock parent was not mandatory */ if (!is_init_done) force = true; } } #endif