// SPDX-License-Identifier: GPL-2.0-only
/*
 * mmp factor clock operation source file
 *
 * Copyright (C) 2012 Marvell
 * Chao Xie <xiechao.mail@gmail.com>
 */

#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 int clk_factor_determine_rate(struct clk_hw *hw,
                                     struct clk_rate_request *req)
{
        struct mmp_clk_factor *factor = to_clk_factor(hw);
        u64 rate = 0, prev_rate;
        struct u32_fract *d;
        int i;

        for (i = 0; i < factor->ftbl_cnt; i++) {
                d = &factor->ftbl[i];

                prev_rate = rate;
                rate = (u64)(req->best_parent_rate) * d->denominator;
                do_div(rate, d->numerator * factor->masks->factor);
                if (rate > req->rate)
                        break;
        }

        if ((i == 0) || (i == factor->ftbl_cnt))
                req->rate = rate;
        else if ((req->rate - prev_rate) > (rate - req->rate))
                req->rate = rate;
        else
                req->rate = prev_rate;

        return 0;
}

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;
        struct u32_fract d;
        unsigned int val;
        u64 rate;

        val = readl_relaxed(factor->base);

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

        /* calculate denominator */
        d.denominator = (val >> masks->den_shift) & masks->den_mask;
        if (!d.denominator)
                return 0;

        rate = (u64)parent_rate * d.denominator;
        do_div(rate, d.numerator * 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;
        struct u32_fract *d;
        u64 rate = 0;

        for (i = 0; i < factor->ftbl_cnt; i++) {
                d = &factor->ftbl[i];

                rate = (u64)prate * d->denominator;
                do_div(rate, d->numerator * factor->masks->factor);
                if (rate > drate)
                        break;
        }
        d = i ? &factor->ftbl[i - 1] : &factor->ftbl[0];

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

        val = readl_relaxed(factor->base);

        val &= ~(masks->num_mask << masks->num_shift);
        val |= (d->numerator & masks->num_mask) << masks->num_shift;

        val &= ~(masks->den_mask << masks->den_shift);
        val |= (d->denominator & 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;
        struct u32_fract d;
        u32 val;
        int i;
        unsigned long flags = 0;

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

        val = readl(factor->base);

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

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

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

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

                val &= ~(masks->den_mask << masks->den_shift);
                val |= (factor->ftbl[0].denominator & 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,
        .determine_rate = clk_factor_determine_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 u32_fract *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_obj(*factor);
        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;
}