/*
 * Copyright (c) 2013 NVIDIA CORPORATION.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

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

#define to_clk_composite(_hw) container_of(_hw, struct clk_composite, hw)

static u8 clk_composite_get_parent(struct clk_hw *hw)
{
        struct clk_composite *composite = to_clk_composite(hw);
        const struct clk_ops *mux_ops = composite->mux_ops;
        struct clk_hw *mux_hw = composite->mux_hw;

        __clk_hw_set_clk(mux_hw, hw);

        return mux_ops->get_parent(mux_hw);
}

static int clk_composite_set_parent(struct clk_hw *hw, u8 index)
{
        struct clk_composite *composite = to_clk_composite(hw);
        const struct clk_ops *mux_ops = composite->mux_ops;
        struct clk_hw *mux_hw = composite->mux_hw;

        __clk_hw_set_clk(mux_hw, hw);

        return mux_ops->set_parent(mux_hw, index);
}

static unsigned long clk_composite_recalc_rate(struct clk_hw *hw,
                                            unsigned long parent_rate)
{
        struct clk_composite *composite = to_clk_composite(hw);
        const struct clk_ops *rate_ops = composite->rate_ops;
        struct clk_hw *rate_hw = composite->rate_hw;

        __clk_hw_set_clk(rate_hw, hw);

        return rate_ops->recalc_rate(rate_hw, parent_rate);
}

static int clk_composite_determine_rate(struct clk_hw *hw,
                                        struct clk_rate_request *req)
{
        struct clk_composite *composite = to_clk_composite(hw);
        const struct clk_ops *rate_ops = composite->rate_ops;
        const struct clk_ops *mux_ops = composite->mux_ops;
        struct clk_hw *rate_hw = composite->rate_hw;
        struct clk_hw *mux_hw = composite->mux_hw;
        struct clk_hw *parent;
        unsigned long parent_rate;
        long tmp_rate, best_rate = 0;
        unsigned long rate_diff;
        unsigned long best_rate_diff = ULONG_MAX;
        long rate;
        int i;

        if (rate_hw && rate_ops && rate_ops->determine_rate) {
                __clk_hw_set_clk(rate_hw, hw);
                return rate_ops->determine_rate(rate_hw, req);
        } else if (rate_hw && rate_ops && rate_ops->round_rate &&
                   mux_hw && mux_ops && mux_ops->set_parent) {
                req->best_parent_hw = NULL;

                if (clk_hw_get_flags(hw) & CLK_SET_RATE_NO_REPARENT) {
                        parent = clk_hw_get_parent(mux_hw);
                        req->best_parent_hw = parent;
                        req->best_parent_rate = clk_hw_get_rate(parent);

                        rate = rate_ops->round_rate(rate_hw, req->rate,
                                                    &req->best_parent_rate);
                        if (rate < 0)
                                return rate;

                        req->rate = rate;
                        return 0;
                }

                for (i = 0; i < clk_hw_get_num_parents(mux_hw); i++) {
                        parent = clk_hw_get_parent_by_index(mux_hw, i);
                        if (!parent)
                                continue;

                        parent_rate = clk_hw_get_rate(parent);

                        tmp_rate = rate_ops->round_rate(rate_hw, req->rate,
                                                        &parent_rate);
                        if (tmp_rate < 0)
                                continue;

                        rate_diff = abs(req->rate - tmp_rate);

                        if (!rate_diff || !req->best_parent_hw
                                       || best_rate_diff > rate_diff) {
                                req->best_parent_hw = parent;
                                req->best_parent_rate = parent_rate;
                                best_rate_diff = rate_diff;
                                best_rate = tmp_rate;
                        }

                        if (!rate_diff)
                                return 0;
                }

                req->rate = best_rate;
                return 0;
        } else if (mux_hw && mux_ops && mux_ops->determine_rate) {
                __clk_hw_set_clk(mux_hw, hw);
                return mux_ops->determine_rate(mux_hw, req);
        } else {
                pr_err("clk: clk_composite_determine_rate function called, but no mux or rate callback set!\n");
                return -EINVAL;
        }
}

static long clk_composite_round_rate(struct clk_hw *hw, unsigned long rate,
                                  unsigned long *prate)
{
        struct clk_composite *composite = to_clk_composite(hw);
        const struct clk_ops *rate_ops = composite->rate_ops;
        struct clk_hw *rate_hw = composite->rate_hw;

        __clk_hw_set_clk(rate_hw, hw);

        return rate_ops->round_rate(rate_hw, rate, prate);
}

static int clk_composite_set_rate(struct clk_hw *hw, unsigned long rate,
                               unsigned long parent_rate)
{
        struct clk_composite *composite = to_clk_composite(hw);
        const struct clk_ops *rate_ops = composite->rate_ops;
        struct clk_hw *rate_hw = composite->rate_hw;

        __clk_hw_set_clk(rate_hw, hw);

        return rate_ops->set_rate(rate_hw, rate, parent_rate);
}

static int clk_composite_is_enabled(struct clk_hw *hw)
{
        struct clk_composite *composite = to_clk_composite(hw);
        const struct clk_ops *gate_ops = composite->gate_ops;
        struct clk_hw *gate_hw = composite->gate_hw;

        __clk_hw_set_clk(gate_hw, hw);

        return gate_ops->is_enabled(gate_hw);
}

static int clk_composite_enable(struct clk_hw *hw)
{
        struct clk_composite *composite = to_clk_composite(hw);
        const struct clk_ops *gate_ops = composite->gate_ops;
        struct clk_hw *gate_hw = composite->gate_hw;

        __clk_hw_set_clk(gate_hw, hw);

        return gate_ops->enable(gate_hw);
}

static void clk_composite_disable(struct clk_hw *hw)
{
        struct clk_composite *composite = to_clk_composite(hw);
        const struct clk_ops *gate_ops = composite->gate_ops;
        struct clk_hw *gate_hw = composite->gate_hw;

        __clk_hw_set_clk(gate_hw, hw);

        gate_ops->disable(gate_hw);
}

struct clk *clk_register_composite(struct device *dev, const char *name,
                        const char * const *parent_names, int num_parents,
                        struct clk_hw *mux_hw, const struct clk_ops *mux_ops,
                        struct clk_hw *rate_hw, const struct clk_ops *rate_ops,
                        struct clk_hw *gate_hw, const struct clk_ops *gate_ops,
                        unsigned long flags)
{
        struct clk *clk;
        struct clk_init_data init;
        struct clk_composite *composite;
        struct clk_ops *clk_composite_ops;

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

        init.name = name;
        init.flags = flags | CLK_IS_BASIC;
        init.parent_names = parent_names;
        init.num_parents = num_parents;

        clk_composite_ops = &composite->ops;

        if (mux_hw && mux_ops) {
                if (!mux_ops->get_parent) {
                        clk = ERR_PTR(-EINVAL);
                        goto err;
                }

                composite->mux_hw = mux_hw;
                composite->mux_ops = mux_ops;
                clk_composite_ops->get_parent = clk_composite_get_parent;
                if (mux_ops->set_parent)
                        clk_composite_ops->set_parent = clk_composite_set_parent;
                if (mux_ops->determine_rate)
                        clk_composite_ops->determine_rate = clk_composite_determine_rate;
        }

        if (rate_hw && rate_ops) {
                if (!rate_ops->recalc_rate) {
                        clk = ERR_PTR(-EINVAL);
                        goto err;
                }
                clk_composite_ops->recalc_rate = clk_composite_recalc_rate;

                if (rate_ops->determine_rate)
                        clk_composite_ops->determine_rate =
                                clk_composite_determine_rate;
                else if (rate_ops->round_rate)
                        clk_composite_ops->round_rate =
                                clk_composite_round_rate;

                /* .set_rate requires either .round_rate or .determine_rate */
                if (rate_ops->set_rate) {
                        if (rate_ops->determine_rate || rate_ops->round_rate)
                                clk_composite_ops->set_rate =
                                                clk_composite_set_rate;
                        else
                                WARN(1, "%s: missing round_rate op is required\n",
                                                __func__);
                }

                composite->rate_hw = rate_hw;
                composite->rate_ops = rate_ops;
        }

        if (gate_hw && gate_ops) {
                if (!gate_ops->is_enabled || !gate_ops->enable ||
                    !gate_ops->disable) {
                        clk = ERR_PTR(-EINVAL);
                        goto err;
                }

                composite->gate_hw = gate_hw;
                composite->gate_ops = gate_ops;
                clk_composite_ops->is_enabled = clk_composite_is_enabled;
                clk_composite_ops->enable = clk_composite_enable;
                clk_composite_ops->disable = clk_composite_disable;
        }

        init.ops = clk_composite_ops;
        composite->hw.init = &init;

        clk = clk_register(dev, &composite->hw);
        if (IS_ERR(clk))
                goto err;

        if (composite->mux_hw)
                composite->mux_hw->clk = clk;

        if (composite->rate_hw)
                composite->rate_hw->clk = clk;

        if (composite->gate_hw)
                composite->gate_hw->clk = clk;

        return clk;

err:
        kfree(composite);
        return clk;
}