/*
 * 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.h>
#include <linux/clk-provider.h>
#include <linux/delay.h>

#include "ccu_gate.h"
#include "ccu_mux.h"

static u16 ccu_mux_get_prediv(struct ccu_common *common,
                              struct ccu_mux_internal *cm,
                              int parent_index)
{
        u16 prediv = 1;
        u32 reg;

        if (!((common->features & CCU_FEATURE_FIXED_PREDIV) ||
              (common->features & CCU_FEATURE_VARIABLE_PREDIV) ||
              (common->features & CCU_FEATURE_ALL_PREDIV)))
                return 1;

        if (common->features & CCU_FEATURE_ALL_PREDIV)
                return common->prediv;

        reg = readl(common->base + common->reg);
        if (parent_index < 0) {
                parent_index = reg >> cm->shift;
                parent_index &= (1 << cm->width) - 1;
        }

        if (common->features & CCU_FEATURE_FIXED_PREDIV) {
                int i;

                for (i = 0; i < cm->n_predivs; i++)
                        if (parent_index == cm->fixed_predivs[i].index)
                                prediv = cm->fixed_predivs[i].div;
        }

        if (common->features & CCU_FEATURE_VARIABLE_PREDIV) {
                int i;

                for (i = 0; i < cm->n_var_predivs; i++)
                        if (parent_index == cm->var_predivs[i].index) {
                                u8 div;

                                div = reg >> cm->var_predivs[i].shift;
                                div &= (1 << cm->var_predivs[i].width) - 1;
                                prediv = div + 1;
                        }
        }

        return prediv;
}

unsigned long ccu_mux_helper_apply_prediv(struct ccu_common *common,
                                          struct ccu_mux_internal *cm,
                                          int parent_index,
                                          unsigned long parent_rate)
{
        return parent_rate / ccu_mux_get_prediv(common, cm, parent_index);
}

static unsigned long ccu_mux_helper_unapply_prediv(struct ccu_common *common,
                                            struct ccu_mux_internal *cm,
                                            int parent_index,
                                            unsigned long parent_rate)
{
        return parent_rate * ccu_mux_get_prediv(common, cm, parent_index);
}

int ccu_mux_helper_determine_rate(struct ccu_common *common,
                                  struct ccu_mux_internal *cm,
                                  struct clk_rate_request *req,
                                  unsigned long (*round)(struct ccu_mux_internal *,
                                                         struct clk_hw *,
                                                         unsigned long *,
                                                         unsigned long,
                                                         void *),
                                  void *data)
{
        unsigned long best_parent_rate = 0, best_rate = 0;
        struct clk_hw *best_parent, *hw = &common->hw;
        unsigned int i;

        if (clk_hw_get_flags(hw) & CLK_SET_RATE_NO_REPARENT) {
                unsigned long adj_parent_rate;

                best_parent = clk_hw_get_parent(hw);
                best_parent_rate = clk_hw_get_rate(best_parent);
                adj_parent_rate = ccu_mux_helper_apply_prediv(common, cm, -1,
                                                              best_parent_rate);

                best_rate = round(cm, best_parent, &adj_parent_rate,
                                  req->rate, data);

                /*
                 * adj_parent_rate might have been modified by our clock.
                 * Unapply the pre-divider if there's one, and give
                 * the actual frequency the parent needs to run at.
                 */
                best_parent_rate = ccu_mux_helper_unapply_prediv(common, cm, -1,
                                                                 adj_parent_rate);

                goto out;
        }

        for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
                unsigned long tmp_rate, parent_rate;
                struct clk_hw *parent;

                parent = clk_hw_get_parent_by_index(hw, i);
                if (!parent)
                        continue;

                parent_rate = ccu_mux_helper_apply_prediv(common, cm, i,
                                                          clk_hw_get_rate(parent));

                tmp_rate = round(cm, parent, &parent_rate, req->rate, data);

                /*
                 * parent_rate might have been modified by our clock.
                 * Unapply the pre-divider if there's one, and give
                 * the actual frequency the parent needs to run at.
                 */
                parent_rate = ccu_mux_helper_unapply_prediv(common, cm, i,
                                                            parent_rate);
                if (tmp_rate == req->rate) {
                        best_parent = parent;
                        best_parent_rate = parent_rate;
                        best_rate = tmp_rate;
                        goto out;
                }

                if ((req->rate - tmp_rate) < (req->rate - best_rate)) {
                        best_rate = tmp_rate;
                        best_parent_rate = parent_rate;
                        best_parent = parent;
                }
        }

        if (best_rate == 0)
                return -EINVAL;

out:
        req->best_parent_hw = best_parent;
        req->best_parent_rate = best_parent_rate;
        req->rate = best_rate;
        return 0;
}

u8 ccu_mux_helper_get_parent(struct ccu_common *common,
                             struct ccu_mux_internal *cm)
{
        u32 reg;
        u8 parent;

        reg = readl(common->base + common->reg);
        parent = reg >> cm->shift;
        parent &= (1 << cm->width) - 1;

        if (cm->table) {
                int num_parents = clk_hw_get_num_parents(&common->hw);
                int i;

                for (i = 0; i < num_parents; i++)
                        if (cm->table[i] == parent)
                                return i;
        }

        return parent;
}

int ccu_mux_helper_set_parent(struct ccu_common *common,
                              struct ccu_mux_internal *cm,
                              u8 index)
{
        unsigned long flags;
        u32 reg;

        if (cm->table)
                index = cm->table[index];

        spin_lock_irqsave(common->lock, flags);

        reg = readl(common->base + common->reg);
        reg &= ~GENMASK(cm->width + cm->shift - 1, cm->shift);
        writel(reg | (index << cm->shift), common->base + common->reg);

        spin_unlock_irqrestore(common->lock, flags);

        return 0;
}

static void ccu_mux_disable(struct clk_hw *hw)
{
        struct ccu_mux *cm = hw_to_ccu_mux(hw);

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

static int ccu_mux_enable(struct clk_hw *hw)
{
        struct ccu_mux *cm = hw_to_ccu_mux(hw);

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

static int ccu_mux_is_enabled(struct clk_hw *hw)
{
        struct ccu_mux *cm = hw_to_ccu_mux(hw);

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

static u8 ccu_mux_get_parent(struct clk_hw *hw)
{
        struct ccu_mux *cm = hw_to_ccu_mux(hw);

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

static int ccu_mux_set_parent(struct clk_hw *hw, u8 index)
{
        struct ccu_mux *cm = hw_to_ccu_mux(hw);

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

static unsigned long ccu_mux_recalc_rate(struct clk_hw *hw,
                                         unsigned long parent_rate)
{
        struct ccu_mux *cm = hw_to_ccu_mux(hw);

        return ccu_mux_helper_apply_prediv(&cm->common, &cm->mux, -1,
                                           parent_rate);
}

const struct clk_ops ccu_mux_ops = {
        .disable        = ccu_mux_disable,
        .enable         = ccu_mux_enable,
        .is_enabled     = ccu_mux_is_enabled,

        .get_parent     = ccu_mux_get_parent,
        .set_parent     = ccu_mux_set_parent,

        .determine_rate = __clk_mux_determine_rate,
        .recalc_rate    = ccu_mux_recalc_rate,
};

/*
 * This clock notifier is called when the frequency of the of the parent
 * PLL clock is to be changed. The idea is to switch the parent to a
 * stable clock, such as the main oscillator, while the PLL frequency
 * stabilizes.
 */
static int ccu_mux_notifier_cb(struct notifier_block *nb,
                               unsigned long event, void *data)
{
        struct ccu_mux_nb *mux = to_ccu_mux_nb(nb);
        int ret = 0;

        if (event == PRE_RATE_CHANGE) {
                mux->original_index = ccu_mux_helper_get_parent(mux->common,
                                                                mux->cm);
                ret = ccu_mux_helper_set_parent(mux->common, mux->cm,
                                                mux->bypass_index);
        } else if (event == POST_RATE_CHANGE) {
                ret = ccu_mux_helper_set_parent(mux->common, mux->cm,
                                                mux->original_index);
        }

        udelay(mux->delay_us);

        return notifier_from_errno(ret);
}

int ccu_mux_notifier_register(struct clk *clk, struct ccu_mux_nb *mux_nb)
{
        mux_nb->clk_nb.notifier_call = ccu_mux_notifier_cb;

        return clk_notifier_register(clk, &mux_nb->clk_nb);
}