/*
 * SuperH clock framework
 *
 *  Copyright (C) 2005 - 2010  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.
 */
#define pr_fmt(fmt) "clock: " fmt

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/syscore_ops.h>
#include <linux/seq_file.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/debugfs.h>
#include <linux/cpufreq.h>
#include <linux/clk.h>
#include <linux/sh_clk.h>

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

/* clock disable operations are not passed on to hardware during boot */
static int allow_disable;

void clk_rate_table_build(struct clk *clk,
                          struct cpufreq_frequency_table *freq_table,
                          int nr_freqs,
                          struct clk_div_mult_table *src_table,
                          unsigned long *bitmap)
{
        unsigned long mult, div;
        unsigned long freq;
        int i;

        clk->nr_freqs = nr_freqs;

        for (i = 0; i < nr_freqs; i++) {
                div = 1;
                mult = 1;

                if (src_table->divisors && i < src_table->nr_divisors)
                        div = src_table->divisors[i];

                if (src_table->multipliers && i < src_table->nr_multipliers)
                        mult = src_table->multipliers[i];

                if (!div || !mult || (bitmap && !test_bit(i, bitmap)))
                        freq = CPUFREQ_ENTRY_INVALID;
                else
                        freq = clk->parent->rate * mult / div;

                freq_table[i].index = i;
                freq_table[i].frequency = freq;
        }

        /* Termination entry */
        freq_table[i].index = i;
        freq_table[i].frequency = CPUFREQ_TABLE_END;
}

struct clk_rate_round_data;

struct clk_rate_round_data {
        unsigned long rate;
        unsigned int min, max;
        long (*func)(unsigned int, struct clk_rate_round_data *);
        void *arg;
};

#define for_each_frequency(pos, r, freq)                        \
        for (pos = r->min, freq = r->func(pos, r);              \
             pos <= r->max; pos++, freq = r->func(pos, r))      \
                if (unlikely(freq == 0))                        \
                        ;                                       \
                else

static long clk_rate_round_helper(struct clk_rate_round_data *rounder)
{
        unsigned long rate_error, rate_error_prev = ~0UL;
        unsigned long highest, lowest, freq;
        long rate_best_fit = -ENOENT;
        int i;

        highest = 0;
        lowest = ~0UL;

        for_each_frequency(i, rounder, freq) {
                if (freq > highest)
                        highest = freq;
                if (freq < lowest)
                        lowest = freq;

                rate_error = abs(freq - rounder->rate);
                if (rate_error < rate_error_prev) {
                        rate_best_fit = freq;
                        rate_error_prev = rate_error;
                }

                if (rate_error == 0)
                        break;
        }

        if (rounder->rate >= highest)
                rate_best_fit = highest;
        if (rounder->rate <= lowest)
                rate_best_fit = lowest;

        return rate_best_fit;
}

static long clk_rate_table_iter(unsigned int pos,
                                struct clk_rate_round_data *rounder)
{
        struct cpufreq_frequency_table *freq_table = rounder->arg;
        unsigned long freq = freq_table[pos].frequency;

        if (freq == CPUFREQ_ENTRY_INVALID)
                freq = 0;

        return freq;
}

long clk_rate_table_round(struct clk *clk,
                          struct cpufreq_frequency_table *freq_table,
                          unsigned long rate)
{
        struct clk_rate_round_data table_round = {
                .min    = 0,
                .max    = clk->nr_freqs - 1,
                .func   = clk_rate_table_iter,
                .arg    = freq_table,
                .rate   = rate,
        };

        if (clk->nr_freqs < 1)
                return -ENOSYS;

        return clk_rate_round_helper(&table_round);
}

static long clk_rate_div_range_iter(unsigned int pos,
                                    struct clk_rate_round_data *rounder)
{
        return clk_get_rate(rounder->arg) / pos;
}

long clk_rate_div_range_round(struct clk *clk, unsigned int div_min,
                              unsigned int div_max, unsigned long rate)
{
        struct clk_rate_round_data div_range_round = {
                .min    = div_min,
                .max    = div_max,
                .func   = clk_rate_div_range_iter,
                .arg    = clk_get_parent(clk),
                .rate   = rate,
        };

        return clk_rate_round_helper(&div_range_round);
}

int clk_rate_table_find(struct clk *clk,
                        struct cpufreq_frequency_table *freq_table,
                        unsigned long rate)
{
        int i;

        for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++) {
                unsigned long freq = freq_table[i].frequency;

                if (freq == CPUFREQ_ENTRY_INVALID)
                        continue;

                if (freq == rate)
                        return i;
        }

        return -ENOENT;
}

/* Used for clocks that always have same value as the parent clock */
unsigned long followparent_recalc(struct clk *clk)
{
        return clk->parent ? clk->parent->rate : 0;
}

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 && clkp->ops->recalc)
                        clkp->rate = clkp->ops->recalc(clkp);

                propagate_rate(clkp);
        }
}

static void __clk_disable(struct clk *clk)
{
        if (WARN(!clk->usecount, "Trying to disable clock %p with 0 usecount\n",
                 clk))
                return;

        if (!(--clk->usecount)) {
                if (likely(allow_disable && 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 && clkp->ops->recalc)
                        clkp->rate = clkp->ops->recalc(clkp);
                propagate_rate(clkp);
        }
}

static struct clk_mapping dummy_mapping;

static struct clk *lookup_root_clock(struct clk *clk)
{
        while (clk->parent)
                clk = clk->parent;

        return clk;
}

static int clk_establish_mapping(struct clk *clk)
{
        struct clk_mapping *mapping = clk->mapping;

        /*
         * Propagate mappings.
         */
        if (!mapping) {
                struct clk *clkp;

                /*
                 * dummy mapping for root clocks with no specified ranges
                 */
                if (!clk->parent) {
                        clk->mapping = &dummy_mapping;
                        return 0;
                }

                /*
                 * If we're on a child clock and it provides no mapping of its
                 * own, inherit the mapping from its root clock.
                 */
                clkp = lookup_root_clock(clk);
                mapping = clkp->mapping;
                BUG_ON(!mapping);
        }

        /*
         * Establish initial mapping.
         */
        if (!mapping->base && mapping->phys) {
                kref_init(&mapping->ref);

                mapping->base = ioremap_nocache(mapping->phys, mapping->len);
                if (unlikely(!mapping->base))
                        return -ENXIO;
        } else if (mapping->base) {
                /*
                 * Bump the refcount for an existing mapping
                 */
                kref_get(&mapping->ref);
        }

        clk->mapping = mapping;
        return 0;
}

static void clk_destroy_mapping(struct kref *kref)
{
        struct clk_mapping *mapping;

        mapping = container_of(kref, struct clk_mapping, ref);

        iounmap(mapping->base);
}

static void clk_teardown_mapping(struct clk *clk)
{
        struct clk_mapping *mapping = clk->mapping;

        /* Nothing to do */
        if (mapping == &dummy_mapping)
                return;

        kref_put(&mapping->ref, clk_destroy_mapping);
        clk->mapping = NULL;
}

int clk_register(struct clk *clk)
{
        int ret;

        if (IS_ERR_OR_NULL(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;

        ret = clk_establish_mapping(clk);
        if (unlikely(ret))
                goto out_unlock;

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

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

#ifdef CONFIG_SH_CLK_CPG_LEGACY
        if (clk->ops && clk->ops->init)
                clk->ops->init(clk);
#endif

out_unlock:
        mutex_unlock(&clock_list_sem);

        return ret;
}
EXPORT_SYMBOL_GPL(clk_register);

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

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)
{
        int ret = -EOPNOTSUPP;
        unsigned long flags;

        spin_lock_irqsave(&clock_lock, flags);

        if (likely(clk->ops && clk->ops->set_rate)) {
                ret = clk->ops->set_rate(clk, rate);
                if (ret != 0)
                        goto out_unlock;
        } else {
                clk->rate = rate;
                ret = 0;
        }

        if (clk->ops && clk->ops->recalc)
                clk->rate = clk->ops->recalc(clk);

        propagate_rate(clk);

out_unlock:
        spin_unlock_irqrestore(&clock_lock, flags);

        return ret;
}
EXPORT_SYMBOL_GPL(clk_set_rate);

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) {
                        if (clk->ops->recalc)
                                clk->rate = clk->ops->recalc(clk);
                        pr_debug("set parent of %p to %p (new rate %ld)\n",
                                 clk, clk->parent, clk->rate);
                        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);

long clk_round_parent(struct clk *clk, unsigned long target,
                      unsigned long *best_freq, unsigned long *parent_freq,
                      unsigned int div_min, unsigned int div_max)
{
        struct cpufreq_frequency_table *freq, *best = NULL;
        unsigned long error = ULONG_MAX, freq_high, freq_low, div;
        struct clk *parent = clk_get_parent(clk);

        if (!parent) {
                *parent_freq = 0;
                *best_freq = clk_round_rate(clk, target);
                return abs(target - *best_freq);
        }

        for (freq = parent->freq_table; freq->frequency != CPUFREQ_TABLE_END;
             freq++) {
                if (freq->frequency == CPUFREQ_ENTRY_INVALID)
                        continue;

                if (unlikely(freq->frequency / target <= div_min - 1)) {
                        unsigned long freq_max;

                        freq_max = (freq->frequency + div_min / 2) / div_min;
                        if (error > target - freq_max) {
                                error = target - freq_max;
                                best = freq;
                                if (best_freq)
                                        *best_freq = freq_max;
                        }

                        pr_debug("too low freq %u, error %lu\n", freq->frequency,
                                 target - freq_max);

                        if (!error)
                                break;

                        continue;
                }

                if (unlikely(freq->frequency / target >= div_max)) {
                        unsigned long freq_min;

                        freq_min = (freq->frequency + div_max / 2) / div_max;
                        if (error > freq_min - target) {
                                error = freq_min - target;
                                best = freq;
                                if (best_freq)
                                        *best_freq = freq_min;
                        }

                        pr_debug("too high freq %u, error %lu\n", freq->frequency,
                                 freq_min - target);

                        if (!error)
                                break;

                        continue;
                }

                div = freq->frequency / target;
                freq_high = freq->frequency / div;
                freq_low = freq->frequency / (div + 1);

                if (freq_high - target < error) {
                        error = freq_high - target;
                        best = freq;
                        if (best_freq)
                                *best_freq = freq_high;
                }

                if (target - freq_low < error) {
                        error = target - freq_low;
                        best = freq;
                        if (best_freq)
                                *best_freq = freq_low;
                }

                pr_debug("%u / %lu = %lu, / %lu = %lu, best %lu, parent %u\n",
                         freq->frequency, div, freq_high, div + 1, freq_low,
                         *best_freq, best->frequency);

                if (!error)
                        break;
        }

        if (parent_freq)
                *parent_freq = best->frequency;

        return error;
}
EXPORT_SYMBOL_GPL(clk_round_parent);

#ifdef CONFIG_PM
static void clks_core_resume(void)
{
        struct clk *clkp;

        list_for_each_entry(clkp, &clock_list, node) {
                if (likely(clkp->usecount && 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);
                        else if (likely(clkp->ops->recalc))
                                clkp->rate = clkp->ops->recalc(clkp);
                }
        }
}

static struct syscore_ops clks_syscore_ops = {
        .resume = clks_core_resume,
};

static int __init clk_syscore_init(void)
{
        register_syscore_ops(&clks_syscore_ops);

        return 0;
}
subsys_initcall(clk_syscore_init);
#endif

/*
 *      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;
        struct clk *pa = c->parent;
        char s[255];
        char *p = s;

        p += sprintf(p, "%p", c);
        d = debugfs_create_dir(s, pa ? pa->dentry : clk_debugfs_root);
        if (!d)
                return -ENOMEM;
        c->dentry = d;

        d = debugfs_create_u8("usecount", S_IRUGO, c->dentry, (u8 *)&c->usecount);
        if (!d) {
                err = -ENOMEM;
                goto err_out;
        }
        d = debugfs_create_u32("rate", S_IRUGO, c->dentry, (u32 *)&c->rate);
        if (!d) {
                err = -ENOMEM;
                goto err_out;
        }
        d = debugfs_create_x32("flags", S_IRUGO, c->dentry, (u32 *)&c->flags);
        if (!d) {
                err = -ENOMEM;
                goto err_out;
        }
        return 0;

err_out:
        debugfs_remove_recursive(c->dentry);
        return err;
}

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

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

        if (!c->dentry) {
                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, &clock_list, node) {
                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);

static int __init clk_late_init(void)
{
        unsigned long flags;
        struct clk *clk;

        /* disable all clocks with zero use count */
        mutex_lock(&clock_list_sem);
        spin_lock_irqsave(&clock_lock, flags);

        list_for_each_entry(clk, &clock_list, node)
                if (!clk->usecount && clk->ops && clk->ops->disable)
                        clk->ops->disable(clk);

        /* from now on allow clock disable operations */
        allow_disable = 1;

        spin_unlock_irqrestore(&clock_lock, flags);
        mutex_unlock(&clock_list_sem);
        return 0;
}
late_initcall(clk_late_init);