// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2016 Maxime Ripard
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 */

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

#include "ccu_gate.h"
#include "ccu_nkmp.h"

struct _ccu_nkmp {
        unsigned long   n, min_n, max_n;
        unsigned long   k, min_k, max_k;
        unsigned long   m, min_m, max_m;
        unsigned long   p, min_p, max_p;
};

static unsigned long ccu_nkmp_calc_rate(unsigned long parent,
                                        unsigned long n, unsigned long k,
                                        unsigned long m, unsigned long p)
{
        u64 rate = parent;

        rate *= n * k;
        do_div(rate, m * p);

        return rate;
}

static void ccu_nkmp_find_best(unsigned long parent, unsigned long rate,
                               struct _ccu_nkmp *nkmp)
{
        unsigned long best_rate = 0;
        unsigned long best_n = 0, best_k = 0, best_m = 0, best_p = 0;
        unsigned long _n, _k, _m, _p;

        for (_k = nkmp->min_k; _k <= nkmp->max_k; _k++) {
                for (_n = nkmp->min_n; _n <= nkmp->max_n; _n++) {
                        for (_m = nkmp->min_m; _m <= nkmp->max_m; _m++) {
                                for (_p = nkmp->min_p; _p <= nkmp->max_p; _p <<= 1) {
                                        unsigned long tmp_rate;

                                        tmp_rate = ccu_nkmp_calc_rate(parent,
                                                                      _n, _k,
                                                                      _m, _p);

                                        if (tmp_rate > rate)
                                                continue;

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

        nkmp->n = best_n;
        nkmp->k = best_k;
        nkmp->m = best_m;
        nkmp->p = best_p;
}

static void ccu_nkmp_disable(struct clk_hw *hw)
{
        struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);

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

static int ccu_nkmp_enable(struct clk_hw *hw)
{
        struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);

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

static int ccu_nkmp_is_enabled(struct clk_hw *hw)
{
        struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);

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

static unsigned long ccu_nkmp_recalc_rate(struct clk_hw *hw,
                                        unsigned long parent_rate)
{
        struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);
        unsigned long n, m, k, p, rate;
        u32 reg;

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

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

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

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

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

        rate = ccu_nkmp_calc_rate(parent_rate, n, k, m, 1 << p);
        if (nkmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
                rate /= nkmp->fixed_post_div;

        return rate;
}

static long ccu_nkmp_round_rate(struct clk_hw *hw, unsigned long rate,
                              unsigned long *parent_rate)
{
        struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);
        struct _ccu_nkmp _nkmp;

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

        if (nkmp->max_rate && rate > nkmp->max_rate) {
                rate = nkmp->max_rate;
                if (nkmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
                        rate /= nkmp->fixed_post_div;
                return rate;
        }

        _nkmp.min_n = nkmp->n.min ?: 1;
        _nkmp.max_n = nkmp->n.max ?: 1 << nkmp->n.width;
        _nkmp.min_k = nkmp->k.min ?: 1;
        _nkmp.max_k = nkmp->k.max ?: 1 << nkmp->k.width;
        _nkmp.min_m = 1;
        _nkmp.max_m = nkmp->m.max ?: 1 << nkmp->m.width;
        _nkmp.min_p = 1;
        _nkmp.max_p = nkmp->p.max ?: 1 << ((1 << nkmp->p.width) - 1);

        ccu_nkmp_find_best(*parent_rate, rate, &_nkmp);

        rate = ccu_nkmp_calc_rate(*parent_rate, _nkmp.n, _nkmp.k,
                                  _nkmp.m, _nkmp.p);
        if (nkmp->common.features & CCU_FEATURE_FIXED_POSTDIV)
                rate = rate / nkmp->fixed_post_div;

        return rate;
}

static int ccu_nkmp_set_rate(struct clk_hw *hw, unsigned long rate,
                           unsigned long parent_rate)
{
        struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);
        u32 n_mask = 0, k_mask = 0, m_mask = 0, p_mask = 0;
        struct _ccu_nkmp _nkmp;
        unsigned long flags;
        u32 reg;

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

        _nkmp.min_n = nkmp->n.min ?: 1;
        _nkmp.max_n = nkmp->n.max ?: 1 << nkmp->n.width;
        _nkmp.min_k = nkmp->k.min ?: 1;
        _nkmp.max_k = nkmp->k.max ?: 1 << nkmp->k.width;
        _nkmp.min_m = 1;
        _nkmp.max_m = nkmp->m.max ?: 1 << nkmp->m.width;
        _nkmp.min_p = 1;
        _nkmp.max_p = nkmp->p.max ?: 1 << ((1 << nkmp->p.width) - 1);

        ccu_nkmp_find_best(parent_rate, rate, &_nkmp);

        /*
         * If width is 0, GENMASK() macro may not generate expected mask (0)
         * as it falls under undefined behaviour by C standard due to shifts
         * which are equal or greater than width of left operand. This can
         * be easily avoided by explicitly checking if width is 0.
         */
        if (nkmp->n.width)
                n_mask = GENMASK(nkmp->n.width + nkmp->n.shift - 1,
                                 nkmp->n.shift);
        if (nkmp->k.width)
                k_mask = GENMASK(nkmp->k.width + nkmp->k.shift - 1,
                                 nkmp->k.shift);
        if (nkmp->m.width)
                m_mask = GENMASK(nkmp->m.width + nkmp->m.shift - 1,
                                 nkmp->m.shift);
        if (nkmp->p.width)
                p_mask = GENMASK(nkmp->p.width + nkmp->p.shift - 1,
                                 nkmp->p.shift);

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

        reg = readl(nkmp->common.base + nkmp->common.reg);
        reg &= ~(n_mask | k_mask | m_mask | p_mask);

        reg |= ((_nkmp.n - nkmp->n.offset) << nkmp->n.shift) & n_mask;
        reg |= ((_nkmp.k - nkmp->k.offset) << nkmp->k.shift) & k_mask;
        reg |= ((_nkmp.m - nkmp->m.offset) << nkmp->m.shift) & m_mask;
        reg |= (ilog2(_nkmp.p) << nkmp->p.shift) & p_mask;

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

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

        ccu_helper_wait_for_lock(&nkmp->common, nkmp->lock);

        return 0;
}

const struct clk_ops ccu_nkmp_ops = {
        .disable        = ccu_nkmp_disable,
        .enable         = ccu_nkmp_enable,
        .is_enabled     = ccu_nkmp_is_enabled,

        .recalc_rate    = ccu_nkmp_recalc_rate,
        .round_rate     = ccu_nkmp_round_rate,
        .set_rate       = ccu_nkmp_set_rate,
};