// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
 */

#include <linux/clk-provider.h>
#include <linux/clkdev.h>
#include <linux/clk/at91_pmc.h>
#include <linux/of.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>

#include "pmc.h"

#define SYSTEM_MAX_ID           31

#define SYSTEM_MAX_NAME_SZ      32

#define to_clk_system(hw) container_of(hw, struct clk_system, hw)
struct clk_system {
        struct clk_hw hw;
        struct regmap *regmap;
        struct at91_clk_pms pms;
        u8 id;
};

static inline int is_pck(int id)
{
        return (id >= 8) && (id <= 15);
}

static inline bool clk_system_ready(struct regmap *regmap, int id)
{
        unsigned int status;

        regmap_read(regmap, AT91_PMC_SR, &status);

        return !!(status & (1 << id));
}

static int clk_system_prepare(struct clk_hw *hw)
{
        struct clk_system *sys = to_clk_system(hw);

        regmap_write(sys->regmap, AT91_PMC_SCER, 1 << sys->id);

        if (!is_pck(sys->id))
                return 0;

        while (!clk_system_ready(sys->regmap, sys->id))
                cpu_relax();

        return 0;
}

static void clk_system_unprepare(struct clk_hw *hw)
{
        struct clk_system *sys = to_clk_system(hw);

        regmap_write(sys->regmap, AT91_PMC_SCDR, 1 << sys->id);
}

static int clk_system_is_prepared(struct clk_hw *hw)
{
        struct clk_system *sys = to_clk_system(hw);
        unsigned int status;

        regmap_read(sys->regmap, AT91_PMC_SCSR, &status);

        if (!(status & (1 << sys->id)))
                return 0;

        if (!is_pck(sys->id))
                return 1;

        regmap_read(sys->regmap, AT91_PMC_SR, &status);

        return !!(status & (1 << sys->id));
}

static int clk_system_save_context(struct clk_hw *hw)
{
        struct clk_system *sys = to_clk_system(hw);

        sys->pms.status = clk_system_is_prepared(hw);

        return 0;
}

static void clk_system_restore_context(struct clk_hw *hw)
{
        struct clk_system *sys = to_clk_system(hw);

        if (sys->pms.status)
                clk_system_prepare(&sys->hw);
}

static const struct clk_ops system_ops = {
        .prepare = clk_system_prepare,
        .unprepare = clk_system_unprepare,
        .is_prepared = clk_system_is_prepared,
        .save_context = clk_system_save_context,
        .restore_context = clk_system_restore_context,
};

struct clk_hw * __init
at91_clk_register_system(struct regmap *regmap, const char *name,
                         const char *parent_name, struct clk_hw *parent_hw, u8 id,
                         unsigned long flags)
{
        struct clk_system *sys;
        struct clk_hw *hw;
        struct clk_init_data init = {};
        int ret;

        if (!(parent_name || parent_hw) || id > SYSTEM_MAX_ID)
                return ERR_PTR(-EINVAL);

        sys = kzalloc_obj(*sys);
        if (!sys)
                return ERR_PTR(-ENOMEM);

        init.name = name;
        init.ops = &system_ops;
        if (parent_hw)
                init.parent_hws = (const struct clk_hw **)&parent_hw;
        else
                init.parent_names = &parent_name;
        init.num_parents = 1;
        init.flags = CLK_SET_RATE_PARENT | flags;

        sys->id = id;
        sys->hw.init = &init;
        sys->regmap = regmap;

        hw = &sys->hw;
        ret = clk_hw_register(NULL, &sys->hw);
        if (ret) {
                kfree(sys);
                hw = ERR_PTR(ret);
        }

        return hw;
}