/* linux/arch/arm/plat-s3c24xx/clock.c
 *
 * Copyright 2004-2005 Simtec Electronics
 *      Ben Dooks <ben@simtec.co.uk>
 *
 * S3C24XX Core clock control support
 *
 * Based on, and code from linux/arch/arm/mach-versatile/clock.c
 **
 **  Copyright (C) 2004 ARM Limited.
 **  Written by Deep Blue Solutions Limited.
 *
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/sysdev.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/clk.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#if defined(CONFIG_DEBUG_FS)
#include <linux/debugfs.h>
#endif

#include <mach/hardware.h>
#include <asm/irq.h>

#include <plat/cpu-freq.h>

#include <plat/clock.h>
#include <plat/cpu.h>

#include <linux/serial_core.h>
#include <plat/regs-serial.h> /* for s3c24xx_uart_devs */

/* clock information */

static LIST_HEAD(clocks);

/* We originally used an mutex here, but some contexts (see resume)
 * are calling functions such as clk_set_parent() with IRQs disabled
 * causing an BUG to be triggered.
 */
DEFINE_SPINLOCK(clocks_lock);

/* enable and disable calls for use with the clk struct */

static int clk_null_enable(struct clk *clk, int enable)
{
        return 0;
}

static int dev_is_s3c_uart(struct device *dev)
{
        struct platform_device **pdev = s3c24xx_uart_devs;
        int i;
        for (i = 0; i < ARRAY_SIZE(s3c24xx_uart_devs); i++, pdev++)
                if (*pdev && dev == &(*pdev)->dev)
                        return 1;
        return 0;
}

/*
 * Serial drivers call get_clock() very early, before platform bus
 * has been set up, this requires a special check to let them get
 * a proper clock
 */

static int dev_is_platform_device(struct device *dev)
{
        return dev->bus == &platform_bus_type ||
               (dev->bus == NULL && dev_is_s3c_uart(dev));
}

/* Clock API calls */

struct clk *clk_get(struct device *dev, const char *id)
{
        struct clk *p;
        struct clk *clk = ERR_PTR(-ENOENT);
        int idno;

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

        spin_lock(&clocks_lock);

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

        /* check for the case where a device was supplied, but the
         * clock that was being searched for is not device specific */

        if (IS_ERR(clk)) {
                list_for_each_entry(p, &clocks, list) {
                        if (p->id == -1 && strcmp(id, p->name) == 0 &&
                            try_module_get(p->owner)) {
                                clk = p;
                                break;
                        }
                }
        }

        spin_unlock(&clocks_lock);
        return clk;
}

void clk_put(struct clk *clk)
{
        module_put(clk->owner);
}

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

        clk_enable(clk->parent);

        spin_lock(&clocks_lock);

        if ((clk->usage++) == 0)
                (clk->enable)(clk, 1);

        spin_unlock(&clocks_lock);
        return 0;
}

void clk_disable(struct clk *clk)
{
        if (IS_ERR(clk) || clk == NULL)
                return;

        spin_lock(&clocks_lock);

        if ((--clk->usage) == 0)
                (clk->enable)(clk, 0);

        spin_unlock(&clocks_lock);
        clk_disable(clk->parent);
}


unsigned long clk_get_rate(struct clk *clk)
{
        if (IS_ERR(clk))
                return 0;

        if (clk->rate != 0)
                return clk->rate;

        if (clk->ops != NULL && clk->ops->get_rate != NULL)
                return (clk->ops->get_rate)(clk);

        if (clk->parent != NULL)
                return clk_get_rate(clk->parent);

        return clk->rate;
}

long clk_round_rate(struct clk *clk, unsigned long rate)
{
        if (!IS_ERR(clk) && clk->ops && clk->ops->round_rate)
                return (clk->ops->round_rate)(clk, rate);

        return rate;
}

int clk_set_rate(struct clk *clk, unsigned long rate)
{
        int ret;

        if (IS_ERR(clk))
                return -EINVAL;

        /* We do not default just do a clk->rate = rate as
         * the clock may have been made this way by choice.
         */

        WARN_ON(clk->ops == NULL);
        WARN_ON(clk->ops && clk->ops->set_rate == NULL);

        if (clk->ops == NULL || clk->ops->set_rate == NULL)
                return -EINVAL;

        spin_lock(&clocks_lock);
        ret = (clk->ops->set_rate)(clk, rate);
        spin_unlock(&clocks_lock);

        return ret;
}

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

int clk_set_parent(struct clk *clk, struct clk *parent)
{
        int ret = 0;

        if (IS_ERR(clk))
                return -EINVAL;

        spin_lock(&clocks_lock);

        if (clk->ops && clk->ops->set_parent)
                ret = (clk->ops->set_parent)(clk, parent);

        spin_unlock(&clocks_lock);

        return ret;
}

EXPORT_SYMBOL(clk_get);
EXPORT_SYMBOL(clk_put);
EXPORT_SYMBOL(clk_enable);
EXPORT_SYMBOL(clk_disable);
EXPORT_SYMBOL(clk_get_rate);
EXPORT_SYMBOL(clk_round_rate);
EXPORT_SYMBOL(clk_set_rate);
EXPORT_SYMBOL(clk_get_parent);
EXPORT_SYMBOL(clk_set_parent);

/* base clocks */

int clk_default_setrate(struct clk *clk, unsigned long rate)
{
        clk->rate = rate;
        return 0;
}

struct clk_ops clk_ops_def_setrate = {
        .set_rate       = clk_default_setrate,
};

struct clk clk_xtal = {
        .name           = "xtal",
        .id             = -1,
        .rate           = 0,
        .parent         = NULL,
        .ctrlbit        = 0,
};

struct clk clk_ext = {
        .name           = "ext",
        .id             = -1,
};

struct clk clk_epll = {
        .name           = "epll",
        .id             = -1,
};

struct clk clk_mpll = {
        .name           = "mpll",
        .id             = -1,
        .ops            = &clk_ops_def_setrate,
};

struct clk clk_upll = {
        .name           = "upll",
        .id             = -1,
        .parent         = NULL,
        .ctrlbit        = 0,
};

struct clk clk_f = {
        .name           = "fclk",
        .id             = -1,
        .rate           = 0,
        .parent         = &clk_mpll,
        .ctrlbit        = 0,
};

struct clk clk_h = {
        .name           = "hclk",
        .id             = -1,
        .rate           = 0,
        .parent         = NULL,
        .ctrlbit        = 0,
        .ops            = &clk_ops_def_setrate,
};

struct clk clk_p = {
        .name           = "pclk",
        .id             = -1,
        .rate           = 0,
        .parent         = NULL,
        .ctrlbit        = 0,
        .ops            = &clk_ops_def_setrate,
};

struct clk clk_usb_bus = {
        .name           = "usb-bus",
        .id             = -1,
        .rate           = 0,
        .parent         = &clk_upll,
};


struct clk s3c24xx_uclk = {
        .name           = "uclk",
        .id             = -1,
};

/* initialise the clock system */

/**
 * s3c24xx_register_clock() - register a clock
 * @clk: The clock to register
 *
 * Add the specified clock to the list of clocks known by the system.
 */
int s3c24xx_register_clock(struct clk *clk)
{
        if (clk->enable == NULL)
                clk->enable = clk_null_enable;

        /* add to the list of available clocks */

        /* Quick check to see if this clock has already been registered. */
        BUG_ON(clk->list.prev != clk->list.next);

        spin_lock(&clocks_lock);
        list_add(&clk->list, &clocks);
        spin_unlock(&clocks_lock);

        return 0;
}

/**
 * s3c24xx_register_clocks() - register an array of clock pointers
 * @clks: Pointer to an array of struct clk pointers
 * @nr_clks: The number of clocks in the @clks array.
 *
 * Call s3c24xx_register_clock() for all the clock pointers contained
 * in the @clks list. Returns the number of failures.
 */
int s3c24xx_register_clocks(struct clk **clks, int nr_clks)
{
        int fails = 0;

        for (; nr_clks > 0; nr_clks--, clks++) {
                if (s3c24xx_register_clock(*clks) < 0) {
                        struct clk *clk = *clks;
                        printk(KERN_ERR "%s: failed to register %p: %s\n",
                               __func__, clk, clk->name);
                        fails++;
                }
        }

        return fails;
}

/**
 * s3c_register_clocks() - register an array of clocks
 * @clkp: Pointer to the first clock in the array.
 * @nr_clks: Number of clocks to register.
 *
 * Call s3c24xx_register_clock() on the @clkp array given, printing an
 * error if it fails to register the clock (unlikely).
 */
void __init s3c_register_clocks(struct clk *clkp, int nr_clks)
{
        int ret;

        for (; nr_clks > 0; nr_clks--, clkp++) {
                ret = s3c24xx_register_clock(clkp);

                if (ret < 0) {
                        printk(KERN_ERR "Failed to register clock %s (%d)\n",
                               clkp->name, ret);
                }
        }
}

/**
 * s3c_disable_clocks() - disable an array of clocks
 * @clkp: Pointer to the first clock in the array.
 * @nr_clks: Number of clocks to register.
 *
 * for internal use only at initialisation time. disable the clocks in the
 * @clkp array.
 */

void __init s3c_disable_clocks(struct clk *clkp, int nr_clks)
{
        for (; nr_clks > 0; nr_clks--, clkp++)
                (clkp->enable)(clkp, 0);
}

/* initialise all the clocks */

int __init s3c24xx_register_baseclocks(unsigned long xtal)
{
        printk(KERN_INFO "S3C24XX Clocks, Copyright 2004 Simtec Electronics\n");

        clk_xtal.rate = xtal;

        /* register our clocks */

        if (s3c24xx_register_clock(&clk_xtal) < 0)
                printk(KERN_ERR "failed to register master xtal\n");

        if (s3c24xx_register_clock(&clk_mpll) < 0)
                printk(KERN_ERR "failed to register mpll clock\n");

        if (s3c24xx_register_clock(&clk_upll) < 0)
                printk(KERN_ERR "failed to register upll clock\n");

        if (s3c24xx_register_clock(&clk_f) < 0)
                printk(KERN_ERR "failed to register cpu fclk\n");

        if (s3c24xx_register_clock(&clk_h) < 0)
                printk(KERN_ERR "failed to register cpu hclk\n");

        if (s3c24xx_register_clock(&clk_p) < 0)
                printk(KERN_ERR "failed to register cpu pclk\n");

        return 0;
}

#if defined(CONFIG_PM_DEBUG) && defined(CONFIG_DEBUG_FS)
/* debugfs support to trace clock tree hierarchy and attributes */

static struct dentry *clk_debugfs_root;

static int clk_debugfs_register_one(struct clk *c)
{
        int err;
        struct dentry *d, *child, *child_tmp;
        struct clk *pa = c->parent;
        char s[255];
        char *p = s;

        p += sprintf(p, "%s", c->name);

        if (c->id >= 0)
                sprintf(p, ":%d", c->id);

        d = debugfs_create_dir(s, pa ? pa->dent : clk_debugfs_root);
        if (!d)
                return -ENOMEM;

        c->dent = d;

        d = debugfs_create_u8("usecount", S_IRUGO, c->dent, (u8 *)&c->usage);
        if (!d) {
                err = -ENOMEM;
                goto err_out;
        }

        d = debugfs_create_u32("rate", S_IRUGO, c->dent, (u32 *)&c->rate);
        if (!d) {
                err = -ENOMEM;
                goto err_out;
        }
        return 0;

err_out:
        d = c->dent;
        list_for_each_entry_safe(child, child_tmp, &d->d_subdirs, d_u.d_child)
                debugfs_remove(child);
        debugfs_remove(c->dent);
        return err;
}

static int clk_debugfs_register(struct clk *c)
{
        int err;
        struct clk *pa = c->parent;

        if (pa && !pa->dent) {
                err = clk_debugfs_register(pa);
                if (err)
                        return err;
        }

        if (!c->dent) {
                err = clk_debugfs_register_one(c);
                if (err)
                        return err;
        }
        return 0;
}

static int __init clk_debugfs_init(void)
{
        struct clk *c;
        struct dentry *d;
        int err;

        d = debugfs_create_dir("clock", NULL);
        if (!d)
                return -ENOMEM;
        clk_debugfs_root = d;

        list_for_each_entry(c, &clocks, list) {
                err = clk_debugfs_register(c);
                if (err)
                        goto err_out;
        }
        return 0;

err_out:
        debugfs_remove_recursive(clk_debugfs_root);
        return err;
}
late_initcall(clk_debugfs_init);

#endif /* defined(CONFIG_PM_DEBUG) && defined(CONFIG_DEBUG_FS) */