/*
 * mmp factor clock operation source file
 *
 * Copyright (C) 2012 Marvell
 * Chao Xie <xiechao.mail@gmail.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/clk-provider.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/err.h>

#include "clk.h"
/*
 * It is M/N clock
 *
 * Fout from synthesizer can be given from two equations:
 * numerator/denominator = Fin / (Fout * factor)
 */

#define to_clk_factor(hw) container_of(hw, struct mmp_clk_factor, hw)

static long clk_factor_round_rate(struct clk_hw *hw, unsigned long drate,
                unsigned long *prate)
{
        struct mmp_clk_factor *factor = to_clk_factor(hw);
        u64 rate = 0, prev_rate;
        int i;

        for (i = 0; i < factor->ftbl_cnt; i++) {
                prev_rate = rate;
                rate = *prate;
                rate *= factor->ftbl[i].den;
                do_div(rate, factor->ftbl[i].num * factor->masks->factor);

                if (rate > drate)
                        break;
        }
        if ((i == 0) || (i == factor->ftbl_cnt)) {
                return rate;
        } else {
                if ((drate - prev_rate) > (rate - drate))
                        return rate;
                else
                        return prev_rate;
        }
}

static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
                unsigned long parent_rate)
{
        struct mmp_clk_factor *factor = to_clk_factor(hw);
        struct mmp_clk_factor_masks *masks = factor->masks;
        unsigned int val, num, den;
        u64 rate;

        val = readl_relaxed(factor->base);

        /* calculate numerator */
        num = (val >> masks->num_shift) & masks->num_mask;

        /* calculate denominator */
        den = (val >> masks->den_shift) & masks->den_mask;

        if (!den)
                return 0;

        rate = parent_rate;
        rate *= den;
        do_div(rate, num * factor->masks->factor);

        return rate;
}

/* Configures new clock rate*/
static int clk_factor_set_rate(struct clk_hw *hw, unsigned long drate,
                                unsigned long prate)
{
        struct mmp_clk_factor *factor = to_clk_factor(hw);
        struct mmp_clk_factor_masks *masks = factor->masks;
        int i;
        unsigned long val;
        unsigned long flags = 0;
        u64 rate = 0;

        for (i = 0; i < factor->ftbl_cnt; i++) {
                rate = prate;
                rate *= factor->ftbl[i].den;
                do_div(rate, factor->ftbl[i].num * factor->masks->factor);

                if (rate > drate)
                        break;
        }
        if (i > 0)
                i--;

        if (factor->lock)
                spin_lock_irqsave(factor->lock, flags);

        val = readl_relaxed(factor->base);

        val &= ~(masks->num_mask << masks->num_shift);
        val |= (factor->ftbl[i].num & masks->num_mask) << masks->num_shift;

        val &= ~(masks->den_mask << masks->den_shift);
        val |= (factor->ftbl[i].den & masks->den_mask) << masks->den_shift;

        writel_relaxed(val, factor->base);

        if (factor->lock)
                spin_unlock_irqrestore(factor->lock, flags);

        return 0;
}

static int clk_factor_init(struct clk_hw *hw)
{
        struct mmp_clk_factor *factor = to_clk_factor(hw);
        struct mmp_clk_factor_masks *masks = factor->masks;
        u32 val, num, den;
        int i;
        unsigned long flags = 0;

        if (factor->lock)
                spin_lock_irqsave(factor->lock, flags);

        val = readl(factor->base);

        /* calculate numerator */
        num = (val >> masks->num_shift) & masks->num_mask;

        /* calculate denominator */
        den = (val >> masks->den_shift) & masks->den_mask;

        for (i = 0; i < factor->ftbl_cnt; i++)
                if (den == factor->ftbl[i].den && num == factor->ftbl[i].num)
                        break;

        if (i >= factor->ftbl_cnt) {
                val &= ~(masks->num_mask << masks->num_shift);
                val |= (factor->ftbl[0].num & masks->num_mask) <<
                        masks->num_shift;

                val &= ~(masks->den_mask << masks->den_shift);
                val |= (factor->ftbl[0].den & masks->den_mask) <<
                        masks->den_shift;
        }

        if (!(val & masks->enable_mask) || i >= factor->ftbl_cnt) {
                val |= masks->enable_mask;
                writel(val, factor->base);
        }

        if (factor->lock)
                spin_unlock_irqrestore(factor->lock, flags);

        return 0;
}

static const struct clk_ops clk_factor_ops = {
        .recalc_rate = clk_factor_recalc_rate,
        .round_rate = clk_factor_round_rate,
        .set_rate = clk_factor_set_rate,
        .init = clk_factor_init,
};

struct clk *mmp_clk_register_factor(const char *name, const char *parent_name,
                unsigned long flags, void __iomem *base,
                struct mmp_clk_factor_masks *masks,
                struct mmp_clk_factor_tbl *ftbl,
                unsigned int ftbl_cnt, spinlock_t *lock)
{
        struct mmp_clk_factor *factor;
        struct clk_init_data init;
        struct clk *clk;

        if (!masks) {
                pr_err("%s: must pass a clk_factor_mask\n", __func__);
                return ERR_PTR(-EINVAL);
        }

        factor = kzalloc(sizeof(*factor), GFP_KERNEL);
        if (!factor)
                return ERR_PTR(-ENOMEM);

        /* struct clk_aux assignments */
        factor->base = base;
        factor->masks = masks;
        factor->ftbl = ftbl;
        factor->ftbl_cnt = ftbl_cnt;
        factor->hw.init = &init;
        factor->lock = lock;

        init.name = name;
        init.ops = &clk_factor_ops;
        init.flags = flags;
        init.parent_names = &parent_name;
        init.num_parents = 1;

        clk = clk_register(NULL, &factor->hw);
        if (IS_ERR_OR_NULL(clk))
                kfree(factor);

        return clk;
}