kernel/cpu/clock.c

/*
 * arch/sh/kernel/cpu/clock.c - SuperH clock framework
 *
 *  Copyright (C) 2005 - 2009  Paul Mundt
 *
 * This clock framework is derived from the OMAP version by:
 *
 *	Copyright (C) 2004 - 2008 Nokia Corporation
 *	Written by Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
 *
 *  Modified for omap shared clock framework by Tony Lindgren <tony@atomide.com>
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/kobject.h>
#include <linux/sysdev.h>
#include <linux/seq_file.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/proc_fs.h>
#include <asm/clock.h>
#include <asm/timer.h>

static LIST_HEAD(clock_list);
static DEFINE_SPINLOCK(clock_lock);
static DEFINE_MUTEX(clock_list_sem);

/*
 * Each subtype is expected to define the init routines for these clocks,
 * as each subtype (or processor family) will have these clocks at the
 * very least. These are all provided through the CPG, which even some of
 * the more quirky parts (such as ST40, SH4-202, etc.) still have.
 *
 * The processor-specific code is expected to register any additional
 * clock sources that are of interest.
 */
static struct clk master_clk = {
	.name		= "master_clk",
	.flags		= CLK_ENABLE_ON_INIT,
	.rate		= CONFIG_SH_PCLK_FREQ,
};

static struct clk module_clk = {
	.name		= "module_clk",
	.parent		= &master_clk,
	.flags		= CLK_ENABLE_ON_INIT,
};

static struct clk bus_clk = {
	.name		= "bus_clk",
	.parent		= &master_clk,
	.flags		= CLK_ENABLE_ON_INIT,
};

static struct clk cpu_clk = {
	.name		= "cpu_clk",
	.parent		= &master_clk,
	.flags		= CLK_ENABLE_ON_INIT,
};

/*
 * The ordering of these clocks matters, do not change it.
 */
static struct clk *onchip_clocks[] = {
	&master_clk,
	&module_clk,
	&bus_clk,
	&cpu_clk,
};

/* Used for clocks that always have same value as the parent clock */
unsigned long followparent_recalc(struct clk *clk)
{
	return clk->parent->rate;
}

int clk_reparent(struct clk *child, struct clk *parent)
{
	list_del_init(&child->sibling);
	if (parent)
		list_add(&child->sibling, &parent->children);
	child->parent = parent;

	/* now do the debugfs renaming to reattach the child
	   to the proper parent */

	return 0;
}

/* Propagate rate to children */
void propagate_rate(struct clk *tclk)
{
	struct clk *clkp;

	list_for_each_entry(clkp, &tclk->children, sibling) {
		if (clkp->ops->recalc)
			clkp->rate = clkp->ops->recalc(clkp);
		propagate_rate(clkp);
	}
}

static void __clk_disable(struct clk *clk)
{
	if (clk->usecount == 0) {
		printk(KERN_ERR "Trying disable clock %s with 0 usecount\n",
		       clk->name);
		WARN_ON(1);
		return;
	}

	if (!(--clk->usecount)) {
		if (likely(clk->ops && clk->ops->disable))
			clk->ops->disable(clk);
		if (likely(clk->parent))
			__clk_disable(clk->parent);
	}
}

void clk_disable(struct clk *clk)
{
	unsigned long flags;

	if (!clk)
		return;

	spin_lock_irqsave(&clock_lock, flags);
	__clk_disable(clk);
	spin_unlock_irqrestore(&clock_lock, flags);
}
EXPORT_SYMBOL_GPL(clk_disable);

static int __clk_enable(struct clk *clk)
{
	int ret = 0;

	if (clk->usecount++ == 0) {
		if (clk->parent) {
			ret = __clk_enable(clk->parent);
			if (unlikely(ret))
				goto err;
		}

		if (clk->ops && clk->ops->enable) {
			ret = clk->ops->enable(clk);
			if (ret) {
				if (clk->parent)
					__clk_disable(clk->parent);
				goto err;
			}
		}
	}

	return ret;
err:
	clk->usecount--;
	return ret;
}

int clk_enable(struct clk *clk)
{
	unsigned long flags;
	int ret;

	if (!clk)
		return -EINVAL;

	spin_lock_irqsave(&clock_lock, flags);
	ret = __clk_enable(clk);
	spin_unlock_irqrestore(&clock_lock, flags);

	return ret;
}
EXPORT_SYMBOL_GPL(clk_enable);

static LIST_HEAD(root_clks);

/**
 * recalculate_root_clocks - recalculate and propagate all root clocks
 *
 * Recalculates all root clocks (clocks with no parent), which if the
 * clock's .recalc is set correctly, should also propagate their rates.
 * Called at init.
 */
void recalculate_root_clocks(void)
{
	struct clk *clkp;

	list_for_each_entry(clkp, &root_clks, sibling) {
		if (clkp->ops->recalc)
			clkp->rate = clkp->ops->recalc(clkp);
		propagate_rate(clkp);
	}
}

int clk_register(struct clk *clk)
{
	if (clk == NULL || IS_ERR(clk))
		return -EINVAL;

	/*
	 * trap out already registered clocks
	 */
	if (clk->node.next || clk->node.prev)
		return 0;

	mutex_lock(&clock_list_sem);

	INIT_LIST_HEAD(&clk->children);
	clk->usecount = 0;

	if (clk->parent)
		list_add(&clk->sibling, &clk->parent->children);
	else
		list_add(&clk->sibling, &root_clks);

	list_add(&clk->node, &clock_list);
	if (clk->ops->init)
		clk->ops->init(clk);
	mutex_unlock(&clock_list_sem);

	return 0;
}
EXPORT_SYMBOL_GPL(clk_register);

void clk_unregister(struct clk *clk)
{
	mutex_lock(&clock_list_sem);
	list_del(&clk->sibling);
	list_del(&clk->node);
	mutex_unlock(&clock_list_sem);
}
EXPORT_SYMBOL_GPL(clk_unregister);

static void clk_enable_init_clocks(void)
{
	struct clk *clkp;

	list_for_each_entry(clkp, &clock_list, node)
		if (clkp->flags & CLK_ENABLE_ON_INIT)
			clk_enable(clkp);
}

unsigned long clk_get_rate(struct clk *clk)
{
	return clk->rate;
}
EXPORT_SYMBOL_GPL(clk_get_rate);

int clk_set_rate(struct clk *clk, unsigned long rate)
{
	return clk_set_rate_ex(clk, rate, 0);
}
EXPORT_SYMBOL_GPL(clk_set_rate);

int clk_set_rate_ex(struct clk *clk, unsigned long rate, int algo_id)
{
	int ret = -EOPNOTSUPP;

	if (likely(clk->ops && clk->ops->set_rate)) {
		unsigned long flags;

		spin_lock_irqsave(&clock_lock, flags);
		ret = clk->ops->set_rate(clk, rate, algo_id);
		if (ret == 0) {
			if (clk->ops->recalc)
				clk->rate = clk->ops->recalc(clk);
			propagate_rate(clk);
		}
		spin_unlock_irqrestore(&clock_lock, flags);
	}

	return ret;
}
EXPORT_SYMBOL_GPL(clk_set_rate_ex);

int clk_set_parent(struct clk *clk, struct clk *parent)
{
	unsigned long flags;
	int ret = -EINVAL;

	if (!parent || !clk)
		return ret;
	if (clk->parent == parent)
		return 0;

	spin_lock_irqsave(&clock_lock, flags);
	if (clk->usecount == 0) {
		if (clk->ops->set_parent)
			ret = clk->ops->set_parent(clk, parent);
		else
			ret = clk_reparent(clk, parent);

		if (ret == 0) {
			pr_debug("clock: set parent of %s to %s (new rate %ld)\n",
				 clk->name, clk->parent->name, clk->rate);
			if (clk->ops->recalc)
				clk->rate = clk->ops->recalc(clk);
			propagate_rate(clk);
		}
	} else
		ret = -EBUSY;
	spin_unlock_irqrestore(&clock_lock, flags);

	return ret;
}
EXPORT_SYMBOL_GPL(clk_set_parent);

struct clk *clk_get_parent(struct clk *clk)
{
	return clk->parent;
}
EXPORT_SYMBOL_GPL(clk_get_parent);

long clk_round_rate(struct clk *clk, unsigned long rate)
{
	if (likely(clk->ops && clk->ops->round_rate)) {
		unsigned long flags, rounded;

		spin_lock_irqsave(&clock_lock, flags);
		rounded = clk->ops->round_rate(clk, rate);
		spin_unlock_irqrestore(&clock_lock, flags);

		return rounded;
	}

	return clk_get_rate(clk);
}
EXPORT_SYMBOL_GPL(clk_round_rate);

/*
 * Returns a clock. Note that we first try to use device id on the bus
 * and clock name. If this fails, we try to use clock name only.
 */
struct clk *clk_get(struct device *dev, const char *id)
{
	struct clk *p, *clk = ERR_PTR(-ENOENT);
	int idno;

	if (dev == NULL || dev->bus != &platform_bus_type)
		idno = -1;
	else
		idno = to_platform_device(dev)->id;

	mutex_lock(&clock_list_sem);
	list_for_each_entry(p, &clock_list, node) {
		if (p->id == idno &&
		    strcmp(id, p->name) == 0 && try_module_get(p->owner)) {
			clk = p;
			goto found;
		}
	}

	list_for_each_entry(p, &clock_list, node) {
		if (strcmp(id, p->name) == 0 && try_module_get(p->owner)) {
			clk = p;
			break;
		}
	}

found:
	mutex_unlock(&clock_list_sem);

	return clk;
}
EXPORT_SYMBOL_GPL(clk_get);

void clk_put(struct clk *clk)
{
	if (clk && !IS_ERR(clk))
		module_put(clk->owner);
}
EXPORT_SYMBOL_GPL(clk_put);

void __init __attribute__ ((weak))
arch_init_clk_ops(struct clk_ops **ops, int type)
{
}

int __init __attribute__ ((weak))
arch_clk_init(void)
{
	return 0;
}

static int show_clocks(char *buf, char **start, off_t off,
		       int len, int *eof, void *data)
{
	struct clk *clk;
	char *p = buf;

	list_for_each_entry_reverse(clk, &clock_list, node) {
		unsigned long rate = clk_get_rate(clk);

		p += sprintf(p, "%-12s\t: %ld.%02ldMHz\t%s\n", clk->name,
			     rate / 1000000, (rate % 1000000) / 10000,
			      (clk->usecount > 0) ?  "enabled" : "disabled");
	}

	return p - buf;
}

#ifdef CONFIG_PM
static int clks_sysdev_suspend(struct sys_device *dev, pm_message_t state)
{
	static pm_message_t prev_state;
	struct clk *clkp;

	switch (state.event) {
	case PM_EVENT_ON:
		/* Resumeing from hibernation */
		if (prev_state.event != PM_EVENT_FREEZE)
			break;

		list_for_each_entry(clkp, &clock_list, node) {
			if (likely(clkp->ops)) {
				unsigned long rate = clkp->rate;

				if (likely(clkp->ops->set_parent))
					clkp->ops->set_parent(clkp,
						clkp->parent);
				if (likely(clkp->ops->set_rate))
					clkp->ops->set_rate(clkp,
						rate, NO_CHANGE);
				else if (likely(clkp->ops->recalc))
					clkp->rate = clkp->ops->recalc(clkp);
			}
		}
		break;
	case PM_EVENT_FREEZE:
		break;
	case PM_EVENT_SUSPEND:
		break;
	}

	prev_state = state;
	return 0;
}

static int clks_sysdev_resume(struct sys_device *dev)
{
	return clks_sysdev_suspend(dev, PMSG_ON);
}

static struct sysdev_class clks_sysdev_class = {
	.name = "clks",
};

static struct sysdev_driver clks_sysdev_driver = {
	.suspend = clks_sysdev_suspend,
	.resume = clks_sysdev_resume,
};

static struct sys_device clks_sysdev_dev = {
	.cls = &clks_sysdev_class,
};

static int __init clk_sysdev_init(void)
{
	sysdev_class_register(&clks_sysdev_class);
	sysdev_driver_register(&clks_sysdev_class, &clks_sysdev_driver);
	sysdev_register(&clks_sysdev_dev);

	return 0;
}
subsys_initcall(clk_sysdev_init);
#endif

int __init clk_init(void)
{
	int i, ret = 0;

	BUG_ON(!master_clk.rate);

	for (i = 0; i < ARRAY_SIZE(onchip_clocks); i++) {
		struct clk *clk = onchip_clocks[i];

		arch_init_clk_ops(&clk->ops, i);
		ret |= clk_register(clk);
	}

	ret |= arch_clk_init();

	/* Kick the child clocks.. */
	recalculate_root_clocks();

	/* Enable the necessary init clocks */
	clk_enable_init_clocks();

	return ret;
}

static int __init clk_proc_init(void)
{
	struct proc_dir_entry *p;
	p = create_proc_read_entry("clocks", S_IRUSR, NULL,
				   show_clocks, NULL);
	if (unlikely(!p))
		return -EINVAL;

	return 0;
}
subsys_initcall(clk_proc_init);