/*
 * Copyright (C) 2016 Maxime Ripard
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 *
 * 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.
 */

#include <linux/clk-provider.h>

#include "ccu_gate.h"
#include "ccu_mp.h"

static void ccu_mp_find_best(unsigned long parent, unsigned long rate,
                             unsigned int max_m, unsigned int max_p,
                             unsigned int *m, unsigned int *p)
{
        unsigned long best_rate = 0;
        unsigned int best_m = 0, best_p = 0;
        unsigned int _m, _p;

        for (_p = 1; _p <= max_p; _p <<= 1) {
                for (_m = 1; _m <= max_m; _m++) {
                        unsigned long tmp_rate = parent / _p / _m;

                        if (tmp_rate > rate)
                                continue;

                        if ((rate - tmp_rate) < (rate - best_rate)) {
                                best_rate = tmp_rate;
                                best_m = _m;
                                best_p = _p;
                        }
                }
        }

        *m = best_m;
        *p = best_p;
}

static unsigned long ccu_mp_find_best_with_parent_adj(struct clk_hw *hw,
                                                      unsigned long *parent,
                                                      unsigned long rate,
                                                      unsigned int max_m,
                                                      unsigned int max_p)
{
        unsigned long parent_rate_saved;
        unsigned long parent_rate, now;
        unsigned long best_rate = 0;
        unsigned int _m, _p, div;
        unsigned long maxdiv;

        parent_rate_saved = *parent;

        /*
         * The maximum divider we can use without overflowing
         * unsigned long in rate * m * p below
         */
        maxdiv = max_m * max_p;
        maxdiv = min(ULONG_MAX / rate, maxdiv);

        for (_p = 1; _p <= max_p; _p <<= 1) {
                for (_m = 1; _m <= max_m; _m++) {
                        div = _m * _p;

                        if (div > maxdiv)
                                break;

                        if (rate * div == parent_rate_saved) {
                                /*
                                 * It's the most ideal case if the requested
                                 * rate can be divided from parent clock without
                                 * needing to change parent rate, so return the
                                 * divider immediately.
                                 */
                                *parent = parent_rate_saved;
                                return rate;
                        }

                        parent_rate = clk_hw_round_rate(hw, rate * div);
                        now = parent_rate / div;

                        if (now <= rate && now > best_rate) {
                                best_rate = now;
                                *parent = parent_rate;

                                if (now == rate)
                                        return rate;
                        }
                }
        }

        return best_rate;
}

static unsigned long ccu_mp_round_rate(struct ccu_mux_internal *mux,
                                       struct clk_hw *hw,
                                       unsigned long *parent_rate,
                                       unsigned long rate,
                                       void *data)
{
        struct ccu_mp *cmp = data;
        unsigned int max_m, max_p;
        unsigned int m, p;

        if (cmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
                rate *= cmp->fixed_post_div;

        max_m = cmp->m.max ?: 1 << cmp->m.width;
        max_p = cmp->p.max ?: 1 << ((1 << cmp->p.width) - 1);

        if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
                ccu_mp_find_best(*parent_rate, rate, max_m, max_p, &m, &p);
                rate = *parent_rate / p / m;
        } else {
                rate = ccu_mp_find_best_with_parent_adj(hw, parent_rate, rate,
                                                        max_m, max_p);
        }

        if (cmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
                rate /= cmp->fixed_post_div;

        return rate;
}

static void ccu_mp_disable(struct clk_hw *hw)
{
        struct ccu_mp *cmp = hw_to_ccu_mp(hw);

        return ccu_gate_helper_disable(&cmp->common, cmp->enable);
}

static int ccu_mp_enable(struct clk_hw *hw)
{
        struct ccu_mp *cmp = hw_to_ccu_mp(hw);

        return ccu_gate_helper_enable(&cmp->common, cmp->enable);
}

static int ccu_mp_is_enabled(struct clk_hw *hw)
{
        struct ccu_mp *cmp = hw_to_ccu_mp(hw);

        return ccu_gate_helper_is_enabled(&cmp->common, cmp->enable);
}

static unsigned long ccu_mp_recalc_rate(struct clk_hw *hw,
                                        unsigned long parent_rate)
{
        struct ccu_mp *cmp = hw_to_ccu_mp(hw);
        unsigned long rate;
        unsigned int m, p;
        u32 reg;

        /* Adjust parent_rate according to pre-dividers */
        parent_rate = ccu_mux_helper_apply_prediv(&cmp->common, &cmp->mux, -1,
                                                  parent_rate);

        reg = readl(cmp->common.base + cmp->common.reg);

        m = reg >> cmp->m.shift;
        m &= (1 << cmp->m.width) - 1;
        m += cmp->m.offset;
        if (!m)
                m++;

        p = reg >> cmp->p.shift;
        p &= (1 << cmp->p.width) - 1;

        rate = (parent_rate >> p) / m;
        if (cmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
                rate /= cmp->fixed_post_div;

        return rate;
}

static int ccu_mp_determine_rate(struct clk_hw *hw,
                                 struct clk_rate_request *req)
{
        struct ccu_mp *cmp = hw_to_ccu_mp(hw);

        return ccu_mux_helper_determine_rate(&cmp->common, &cmp->mux,
                                             req, ccu_mp_round_rate, cmp);
}

static int ccu_mp_set_rate(struct clk_hw *hw, unsigned long rate,
                           unsigned long parent_rate)
{
        struct ccu_mp *cmp = hw_to_ccu_mp(hw);
        unsigned long flags;
        unsigned int max_m, max_p;
        unsigned int m, p;
        u32 reg;

        /* Adjust parent_rate according to pre-dividers */
        parent_rate = ccu_mux_helper_apply_prediv(&cmp->common, &cmp->mux, -1,
                                                  parent_rate);

        max_m = cmp->m.max ?: 1 << cmp->m.width;
        max_p = cmp->p.max ?: 1 << ((1 << cmp->p.width) - 1);

        /* Adjust target rate according to post-dividers */
        if (cmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
                rate = rate * cmp->fixed_post_div;

        ccu_mp_find_best(parent_rate, rate, max_m, max_p, &m, &p);

        spin_lock_irqsave(cmp->common.lock, flags);

        reg = readl(cmp->common.base + cmp->common.reg);
        reg &= ~GENMASK(cmp->m.width + cmp->m.shift - 1, cmp->m.shift);
        reg &= ~GENMASK(cmp->p.width + cmp->p.shift - 1, cmp->p.shift);
        reg |= (m - cmp->m.offset) << cmp->m.shift;
        reg |= ilog2(p) << cmp->p.shift;

        writel(reg, cmp->common.base + cmp->common.reg);

        spin_unlock_irqrestore(cmp->common.lock, flags);

        return 0;
}

static u8 ccu_mp_get_parent(struct clk_hw *hw)
{
        struct ccu_mp *cmp = hw_to_ccu_mp(hw);

        return ccu_mux_helper_get_parent(&cmp->common, &cmp->mux);
}

static int ccu_mp_set_parent(struct clk_hw *hw, u8 index)
{
        struct ccu_mp *cmp = hw_to_ccu_mp(hw);

        return ccu_mux_helper_set_parent(&cmp->common, &cmp->mux, index);
}

const struct clk_ops ccu_mp_ops = {
        .disable        = ccu_mp_disable,
        .enable         = ccu_mp_enable,
        .is_enabled     = ccu_mp_is_enabled,

        .get_parent     = ccu_mp_get_parent,
        .set_parent     = ccu_mp_set_parent,

        .determine_rate = ccu_mp_determine_rate,
        .recalc_rate    = ccu_mp_recalc_rate,
        .set_rate       = ccu_mp_set_rate,
};

/*
 * Support for MMC timing mode switching
 *
 * The MMC clocks on some SoCs support switching between old and
 * new timing modes. A platform specific API is provided to query
 * and set the timing mode on supported SoCs.
 *
 * In addition, a special class of ccu_mp_ops is provided, which
 * takes in to account the timing mode switch. When the new timing
 * mode is active, the clock output rate is halved. This new class
 * is a wrapper around the generic ccu_mp_ops. When clock rates
 * are passed through to ccu_mp_ops callbacks, they are doubled
 * if the new timing mode bit is set, to account for the post
 * divider. Conversely, when clock rates are passed back, they
 * are halved if the mode bit is set.
 */

static unsigned long ccu_mp_mmc_recalc_rate(struct clk_hw *hw,
                                            unsigned long parent_rate)
{
        unsigned long rate = ccu_mp_recalc_rate(hw, parent_rate);
        struct ccu_common *cm = hw_to_ccu_common(hw);
        u32 val = readl(cm->base + cm->reg);

        if (val & CCU_MMC_NEW_TIMING_MODE)
                return rate / 2;
        return rate;
}

static int ccu_mp_mmc_determine_rate(struct clk_hw *hw,
                                     struct clk_rate_request *req)
{
        struct ccu_common *cm = hw_to_ccu_common(hw);
        u32 val = readl(cm->base + cm->reg);
        int ret;

        /* adjust the requested clock rate */
        if (val & CCU_MMC_NEW_TIMING_MODE) {
                req->rate *= 2;
                req->min_rate *= 2;
                req->max_rate *= 2;
        }

        ret = ccu_mp_determine_rate(hw, req);

        /* re-adjust the requested clock rate back */
        if (val & CCU_MMC_NEW_TIMING_MODE) {
                req->rate /= 2;
                req->min_rate /= 2;
                req->max_rate /= 2;
        }

        return ret;
}

static int ccu_mp_mmc_set_rate(struct clk_hw *hw, unsigned long rate,
                               unsigned long parent_rate)
{
        struct ccu_common *cm = hw_to_ccu_common(hw);
        u32 val = readl(cm->base + cm->reg);

        if (val & CCU_MMC_NEW_TIMING_MODE)
                rate *= 2;

        return ccu_mp_set_rate(hw, rate, parent_rate);
}

const struct clk_ops ccu_mp_mmc_ops = {
        .disable        = ccu_mp_disable,
        .enable         = ccu_mp_enable,
        .is_enabled     = ccu_mp_is_enabled,

        .get_parent     = ccu_mp_get_parent,
        .set_parent     = ccu_mp_set_parent,

        .determine_rate = ccu_mp_mmc_determine_rate,
        .recalc_rate    = ccu_mp_mmc_recalc_rate,
        .set_rate       = ccu_mp_mmc_set_rate,
};