clk: Provide not locked variant of of_clk_get_from_provider()
Add helper functions for the of_clk_providers list locking and an unlocked variant of of_clk_get_from_provider(). These functions are intended to be used in the clkdev to avoid race condition in the device tree based clock look up in clk_get(). Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
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4eadfc38c4
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@ -21,6 +21,8 @@
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#include <linux/init.h>
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#include <linux/sched.h>
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#include "clk.h"
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static DEFINE_SPINLOCK(enable_lock);
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static DEFINE_MUTEX(prepare_lock);
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@ -2111,7 +2113,18 @@ static const struct of_device_id __clk_of_table_sentinel
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__used __section(__clk_of_table_end);
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static LIST_HEAD(of_clk_providers);
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static DEFINE_MUTEX(of_clk_lock);
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static DEFINE_MUTEX(of_clk_mutex);
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/* of_clk_provider list locking helpers */
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void of_clk_lock(void)
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{
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mutex_lock(&of_clk_mutex);
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}
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void of_clk_unlock(void)
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{
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mutex_unlock(&of_clk_mutex);
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}
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struct clk *of_clk_src_simple_get(struct of_phandle_args *clkspec,
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void *data)
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@ -2155,9 +2168,9 @@ int of_clk_add_provider(struct device_node *np,
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cp->data = data;
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cp->get = clk_src_get;
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mutex_lock(&of_clk_lock);
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mutex_lock(&of_clk_mutex);
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list_add(&cp->link, &of_clk_providers);
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mutex_unlock(&of_clk_lock);
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mutex_unlock(&of_clk_mutex);
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pr_debug("Added clock from %s\n", np->full_name);
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return 0;
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@ -2172,7 +2185,7 @@ void of_clk_del_provider(struct device_node *np)
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{
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struct of_clk_provider *cp;
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mutex_lock(&of_clk_lock);
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mutex_lock(&of_clk_mutex);
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list_for_each_entry(cp, &of_clk_providers, link) {
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if (cp->node == np) {
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list_del(&cp->link);
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@ -2181,24 +2194,33 @@ void of_clk_del_provider(struct device_node *np)
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break;
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}
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}
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mutex_unlock(&of_clk_lock);
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mutex_unlock(&of_clk_mutex);
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}
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EXPORT_SYMBOL_GPL(of_clk_del_provider);
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struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
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struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec)
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{
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struct of_clk_provider *provider;
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struct clk *clk = ERR_PTR(-ENOENT);
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/* Check if we have such a provider in our array */
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mutex_lock(&of_clk_lock);
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list_for_each_entry(provider, &of_clk_providers, link) {
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if (provider->node == clkspec->np)
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clk = provider->get(clkspec, provider->data);
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if (!IS_ERR(clk))
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break;
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}
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mutex_unlock(&of_clk_lock);
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return clk;
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}
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struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
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{
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struct clk *clk;
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mutex_lock(&of_clk_mutex);
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clk = __of_clk_get_from_provider(clkspec);
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mutex_unlock(&of_clk_mutex);
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return clk;
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}
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16
drivers/clk/clk.h
Normal file
16
drivers/clk/clk.h
Normal file
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@ -0,0 +1,16 @@
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/*
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* linux/drivers/clk/clk.h
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*
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* Copyright (C) 2013 Samsung Electronics Co., Ltd.
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* Sylwester Nawrocki <s.nawrocki@samsung.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
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struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec);
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void of_clk_lock(void);
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void of_clk_unlock(void);
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#endif
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