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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>
hifive-unleashed-5.1
Sylwester Nawrocki 2013-08-23 17:03:43 +02:00
parent 4eadfc38c4
commit d6782c2636
2 changed files with 46 additions and 8 deletions
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38
drivers/clk/clk.c
View File

@ -21,6 +21,8 @@
#include <linux/init.h>
#include <linux/sched.h>
#include "clk.h"
static DEFINE_SPINLOCK(enable_lock);
static DEFINE_MUTEX(prepare_lock);
@ -2111,7 +2113,18 @@ static const struct of_device_id __clk_of_table_sentinel
__used __section(__clk_of_table_end);
static LIST_HEAD(of_clk_providers);
static DEFINE_MUTEX(of_clk_lock);
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)
@ -2155,9 +2168,9 @@ int of_clk_add_provider(struct device_node *np,
cp->data = data;
cp->get = clk_src_get;
mutex_lock(&of_clk_lock);
mutex_lock(&of_clk_mutex);
list_add(&cp->link, &of_clk_providers);
mutex_unlock(&of_clk_lock);
mutex_unlock(&of_clk_mutex);
pr_debug("Added clock from %s\n", np->full_name);
return 0;
@ -2172,7 +2185,7 @@ void of_clk_del_provider(struct device_node *np)
{
struct of_clk_provider *cp;
mutex_lock(&of_clk_lock);
mutex_lock(&of_clk_mutex);
list_for_each_entry(cp, &of_clk_providers, link) {
if (cp->node == np) {
list_del(&cp->link);
@ -2181,24 +2194,33 @@ void of_clk_del_provider(struct device_node *np)
break;
}
}
mutex_unlock(&of_clk_lock);
mutex_unlock(&of_clk_mutex);
}
EXPORT_SYMBOL_GPL(of_clk_del_provider);
struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec)
{
struct of_clk_provider *provider;
struct clk *clk = ERR_PTR(-ENOENT);
/* Check if we have such a provider in our array */
mutex_lock(&of_clk_lock);
list_for_each_entry(provider, &of_clk_providers, link) {
if (provider->node == clkspec->np)
clk = provider->get(clkspec, provider->data);
if (!IS_ERR(clk))
break;
}
mutex_unlock(&of_clk_lock);
return clk;
}
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);
mutex_unlock(&of_clk_mutex);
return clk;
}

16
drivers/clk/clk.h 100644
View File

@ -0,0 +1,16 @@
/*
* linux/drivers/clk/clk.h
*
* Copyright (C) 2013 Samsung Electronics Co., Ltd.
* Sylwester Nawrocki <s.nawrocki@samsung.com>
*
* 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.
*/
#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec);
void of_clk_lock(void);
void of_clk_unlock(void);
#endif