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Commit d6782c26 authored by Sylwester Nawrocki's avatar Sylwester Nawrocki
Browse files

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: default avatarSylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: default avatarKyungmin Park <kyungmin.park@samsung.com>
Acked-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 4eadfc38

drivers/clk/clk.c

+30 −8
Original line number Diff line number Diff line
@@ -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;

}

drivers/clk/clk.h

0 → 100644
+16 −0
Original line number Diff line number Diff line 
/*

 * 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