/*
 * arch/sh/kernel/cpu/clock.c - SuperH clock framework
 *
 *  Copyright (C) 2005, 2006, 2007  Paul Mundt
 *
 * This clock framework is derived from the OMAP version by:
 *
 *      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>
 *
 * 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/kref.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_ALWAYS_ENABLED | CLK_RATE_PROPAGATES,
        .rate           = CONFIG_SH_PCLK_FREQ,
};

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

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

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

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

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

        list_for_each_entry(clkp, &clock_list, node) {
                if (likely(clkp->parent != clk))
                        continue;
                if (likely(clkp->ops && clkp->ops->recalc))
                        clkp->ops->recalc(clkp);
                if (unlikely(clkp->flags & CLK_RATE_PROPAGATES))
                        propagate_rate(clkp);
        }
}

static int __clk_enable(struct clk *clk)
{
        /*
         * See if this is the first time we're enabling the clock, some
         * clocks that are always enabled still require "special"
         * initialization. This is especially true if the clock mode
         * changes and the clock needs to hunt for the proper set of
         * divisors to use before it can effectively recalc.
         */
        if (unlikely(atomic_read(&clk->kref.refcount) == 1))
                if (clk->ops && clk->ops->init)
                        clk->ops->init(clk);

        kref_get(&clk->kref);

        if (clk->flags & CLK_ALWAYS_ENABLED)
                return 0;

        if (likely(clk->ops && clk->ops->enable))
                clk->ops->enable(clk);

        return 0;
}

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

        if (!clk)
                return -EINVAL;

        clk_enable(clk->parent);

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

        return ret;
}
EXPORT_SYMBOL_GPL(clk_enable);

static void clk_kref_release(struct kref *kref)
{
        /* Nothing to do */
}

static void __clk_disable(struct clk *clk)
{
        int count = kref_put(&clk->kref, clk_kref_release);

        if (clk->flags & CLK_ALWAYS_ENABLED)
                return;

        if (!count) {   /* count reaches zero, disable the clock */
                if (likely(clk->ops && clk->ops->disable))
                        clk->ops->disable(clk);
        }
}

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);

        clk_disable(clk->parent);
}
EXPORT_SYMBOL_GPL(clk_disable);

int clk_register(struct clk *clk)
{
        mutex_lock(&clock_list_sem);

        list_add(&clk->node, &clock_list);
        kref_init(&clk->kref);

        mutex_unlock(&clock_list_sem);

        if (clk->flags & CLK_ALWAYS_ENABLED) {
                pr_debug( "Clock '%s' is ALWAYS_ENABLED\n", clk->name);
                if (clk->ops && clk->ops->init)
                        clk->ops->init(clk);
                if (clk->ops && clk->ops->enable)
                        clk->ops->enable(clk);
                pr_debug( "Enabled.");
        }

        return 0;
}
EXPORT_SYMBOL_GPL(clk_register);

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

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);
                spin_unlock_irqrestore(&clock_lock, flags);
        }

        if (unlikely(clk->flags & CLK_RATE_PROPAGATES))
                propagate_rate(clk);

        return ret;
}
EXPORT_SYMBOL_GPL(clk_set_rate_ex);

void clk_recalc_rate(struct clk *clk)
{
        if (likely(clk->ops && clk->ops->recalc)) {
                unsigned long flags;

                spin_lock_irqsave(&clock_lock, flags);
                clk->ops->recalc(clk);
                spin_unlock_irqrestore(&clock_lock, flags);
        }

        if (unlikely(clk->flags & CLK_RATE_PROPAGATES))
                propagate_rate(clk);
}
EXPORT_SYMBOL_GPL(clk_recalc_rate);

int clk_set_parent(struct clk *clk, struct clk *parent)
{
        int ret = -EINVAL;
        struct clk *old;

        if (!parent || !clk)
                return ret;

        old = clk->parent;
        if (likely(clk->ops && clk->ops->set_parent)) {
                unsigned long flags;
                spin_lock_irqsave(&clock_lock, flags);
                ret = clk->ops->set_parent(clk, parent);
                spin_unlock_irqrestore(&clock_lock, flags);
                clk->parent = (ret ? old : parent);
        }

        if (unlikely(clk->flags & CLK_RATE_PROPAGATES))
                propagate_rate(clk);
        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->flags & CLK_ALWAYS_ENABLED) ||
                              (atomic_read(&clk->kref.refcount) != 1)) ?
                             "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) {
                        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->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.. */
        propagate_rate(&master_clk);
        propagate_rate(&bus_clk);

        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);