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/*
* Based on arch/arm/plat-omap/clock.c
*
* Copyright (C) 2004 - 2005 Nokia corporation
* Written by Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
* Modified for omap shared clock framework by Tony Lindgren <tony@atomide.com>
* Copyright 2007 Freescale Semiconductor, Inc. All Rights Reserved.
* Copyright 2008 Juergen Beisert, kernel@pengutronix.de
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
/* #define DEBUG */
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/proc_fs.h>
#include <linux/semaphore.h>
#include <linux/string.h>
#include <mach/clock.h>
static LIST_HEAD(clocks);
static DEFINE_MUTEX(clocks_mutex);
/*-------------------------------------------------------------------------
* Standard clock functions defined in include/linux/clk.h
*-------------------------------------------------------------------------*/
static void __clk_disable(struct clk *clk)
{
if (clk == NULL || IS_ERR(clk))
return;
WARN_ON(!clk->usecount);
if (!(--clk->usecount)) {
if (clk->disable)
clk->disable(clk);
__clk_disable(clk->parent);
}
}
static int __clk_enable(struct clk *clk)
{
if (clk == NULL || IS_ERR(clk))
return -EINVAL;
if (clk->usecount++ == 0) {
__clk_enable(clk->parent);
if (clk->enable)
clk->enable(clk);
}
return 0;
}
/*
* The clk_enable/clk_disable could be called by drivers in atomic context,
* so they should not really hold mutex. Instead, clk_prepare/clk_unprepare
* can hold a mutex, as the pair will only be called in non-atomic context.
* Before migrating to common clk framework, we can have __clk_enable and
* __clk_disable called in clk_prepare/clk_unprepare with mutex held and
* leave clk_enable/clk_disable as the dummy functions.
*/
int clk_prepare(struct clk *clk)
{
int ret = 0;
if (clk == NULL || IS_ERR(clk))
return -EINVAL;
mutex_lock(&clocks_mutex);
ret = __clk_enable(clk);
mutex_unlock(&clocks_mutex);
return ret;
}
EXPORT_SYMBOL(clk_prepare);
void clk_unprepare(struct clk *clk)
{
if (clk == NULL || IS_ERR(clk))
return;
mutex_lock(&clocks_mutex);
__clk_disable(clk);
mutex_unlock(&clocks_mutex);
}
EXPORT_SYMBOL(clk_unprepare);
int clk_enable(struct clk *clk)
{
return 0;
}
EXPORT_SYMBOL(clk_enable);
void clk_disable(struct clk *clk)
{
/* nothing to do */
}
EXPORT_SYMBOL(clk_disable);
/* Retrieve the *current* clock rate. If the clock itself
* does not provide a special calculation routine, ask
* its parent and so on, until one is able to return
* a valid clock rate
*/
unsigned long clk_get_rate(struct clk *clk)
{
if (clk == NULL || IS_ERR(clk))
return 0UL;
if (clk->get_rate)
return clk->get_rate(clk);
return clk_get_rate(clk->parent);
}
EXPORT_SYMBOL(clk_get_rate);
/* Round the requested clock rate to the nearest supported
* rate that is less than or equal to the requested rate.
* This is dependent on the clock's current parent.
*/
long clk_round_rate(struct clk *clk, unsigned long rate)
{
if (clk == NULL || IS_ERR(clk) || !clk->round_rate)
return 0;
return clk->round_rate(clk, rate);
}
EXPORT_SYMBOL(clk_round_rate);
/* Set the clock to the requested clock rate. The rate must
* match a supported rate exactly based on what clk_round_rate returns
*/
int clk_set_rate(struct clk *clk, unsigned long rate)
{
int ret = -EINVAL;
if (clk == NULL || IS_ERR(clk) || clk->set_rate == NULL || rate == 0)
return ret;
mutex_lock(&clocks_mutex);
ret = clk->set_rate(clk, rate);
mutex_unlock(&clocks_mutex);
return ret;
}
EXPORT_SYMBOL(clk_set_rate);
/* Set the clock's parent to another clock source */
int clk_set_parent(struct clk *clk, struct clk *parent)
{
int ret = -EINVAL;
struct clk *old;
if (clk == NULL || IS_ERR(clk) || parent == NULL ||
IS_ERR(parent) || clk->set_parent == NULL)
return ret;
if (clk->usecount)
clk_prepare_enable(parent);
mutex_lock(&clocks_mutex);
ret = clk->set_parent(clk, parent);
if (ret == 0) {
old = clk->parent;
clk->parent = parent;
} else {
old = parent;
}
mutex_unlock(&clocks_mutex);
if (clk->usecount)
clk_disable(old);
return ret;
}
EXPORT_SYMBOL(clk_set_parent);
/* Retrieve the clock's parent clock source */
struct clk *clk_get_parent(struct clk *clk)
{
struct clk *ret = NULL;
if (clk == NULL || IS_ERR(clk))
return ret;
return clk->parent;
}
EXPORT_SYMBOL(clk_get_parent);
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