// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
 */
#include <linux/module.h>
#include <linux/clk-provider.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/platform_device.h>

/*
 * DOC: basic fixed multiplier and divider clock that cannot gate
 *
 * Traits of this clock:
 * prepare - clk_prepare only ensures that parents are prepared
 * enable - clk_enable only ensures that parents are enabled
 * rate - rate is fixed.  clk->rate = parent->rate / div * mult
 * parent - fixed parent.  No clk_set_parent support
 */

static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
                unsigned long parent_rate)
{
        struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
        unsigned long long int rate;

        rate = (unsigned long long int)parent_rate * fix->mult;
        do_div(rate, fix->div);
        return (unsigned long)rate;
}

static long clk_factor_round_rate(struct clk_hw *hw, unsigned long rate,
                                unsigned long *prate)
{
        struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);

        if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) {
                unsigned long best_parent;

                best_parent = (rate / fix->mult) * fix->div;
                *prate = clk_hw_round_rate(clk_hw_get_parent(hw), best_parent);
        }

        return (*prate / fix->div) * fix->mult;
}

static int clk_factor_set_rate(struct clk_hw *hw, unsigned long rate,
                                unsigned long parent_rate)
{
        /*
         * We must report success but we can do so unconditionally because
         * clk_factor_round_rate returns values that ensure this call is a
         * nop.
         */

        return 0;
}

const struct clk_ops clk_fixed_factor_ops = {
        .round_rate = clk_factor_round_rate,
        .set_rate = clk_factor_set_rate,
        .recalc_rate = clk_factor_recalc_rate,
};
EXPORT_SYMBOL_GPL(clk_fixed_factor_ops);

static struct clk_hw *
__clk_hw_register_fixed_factor(struct device *dev, struct device_node *np,
                const char *name, const char *parent_name, int index,
                unsigned long flags, unsigned int mult, unsigned int div)
{
        struct clk_fixed_factor *fix;
        struct clk_init_data init = { };
        struct clk_parent_data pdata = { .index = index };
        struct clk_hw *hw;
        int ret;

        fix = kmalloc(sizeof(*fix), GFP_KERNEL);
        if (!fix)
                return ERR_PTR(-ENOMEM);

        /* struct clk_fixed_factor assignments */
        fix->mult = mult;
        fix->div = div;
        fix->hw.init = &init;

        init.name = name;
        init.ops = &clk_fixed_factor_ops;
        init.flags = flags;
        if (parent_name)
                init.parent_names = &parent_name;
        else
                init.parent_data = &pdata;
        init.num_parents = 1;

        hw = &fix->hw;
        if (dev)
                ret = clk_hw_register(dev, hw);
        else
                ret = of_clk_hw_register(np, hw);
        if (ret) {
                kfree(fix);
                hw = ERR_PTR(ret);
        }

        return hw;
}

struct clk_hw *clk_hw_register_fixed_factor(struct device *dev,
                const char *name, const char *parent_name, unsigned long flags,
                unsigned int mult, unsigned int div)
{
        return __clk_hw_register_fixed_factor(dev, NULL, name, parent_name, -1,
                                              flags, mult, div);
}
EXPORT_SYMBOL_GPL(clk_hw_register_fixed_factor);

struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
                const char *parent_name, unsigned long flags,
                unsigned int mult, unsigned int div)
{
        struct clk_hw *hw;

        hw = clk_hw_register_fixed_factor(dev, name, parent_name, flags, mult,
                                          div);
        if (IS_ERR(hw))
                return ERR_CAST(hw);
        return hw->clk;
}
EXPORT_SYMBOL_GPL(clk_register_fixed_factor);

void clk_unregister_fixed_factor(struct clk *clk)
{
        struct clk_hw *hw;

        hw = __clk_get_hw(clk);
        if (!hw)
                return;

        clk_unregister(clk);
        kfree(to_clk_fixed_factor(hw));
}
EXPORT_SYMBOL_GPL(clk_unregister_fixed_factor);

void clk_hw_unregister_fixed_factor(struct clk_hw *hw)
{
        struct clk_fixed_factor *fix;

        fix = to_clk_fixed_factor(hw);

        clk_hw_unregister(hw);
        kfree(fix);
}
EXPORT_SYMBOL_GPL(clk_hw_unregister_fixed_factor);

#ifdef CONFIG_OF
static const struct of_device_id set_rate_parent_matches[] = {
        { .compatible = "allwinner,sun4i-a10-pll3-2x-clk" },
        { /* Sentinel */ },
};

static struct clk_hw *_of_fixed_factor_clk_setup(struct device_node *node)
{
        struct clk_hw *hw;
        const char *clk_name = node->name;
        unsigned long flags = 0;
        u32 div, mult;
        int ret;

        if (of_property_read_u32(node, "clock-div", &div)) {
                pr_err("%s Fixed factor clock <%pOFn> must have a clock-div property\n",
                        __func__, node);
                return ERR_PTR(-EIO);
        }

        if (of_property_read_u32(node, "clock-mult", &mult)) {
                pr_err("%s Fixed factor clock <%pOFn> must have a clock-mult property\n",
                        __func__, node);
                return ERR_PTR(-EIO);
        }

        of_property_read_string(node, "clock-output-names", &clk_name);

        if (of_match_node(set_rate_parent_matches, node))
                flags |= CLK_SET_RATE_PARENT;

        hw = __clk_hw_register_fixed_factor(NULL, node, clk_name, NULL, 0,
                                            flags, mult, div);
        if (IS_ERR(hw)) {
                /*
                 * Clear OF_POPULATED flag so that clock registration can be
                 * attempted again from probe function.
                 */
                of_node_clear_flag(node, OF_POPULATED);
                return ERR_CAST(hw);
        }

        ret = of_clk_add_hw_provider(node, of_clk_hw_simple_get, hw);
        if (ret) {
                clk_hw_unregister_fixed_factor(hw);
                return ERR_PTR(ret);
        }

        return hw;
}

/**
 * of_fixed_factor_clk_setup() - Setup function for simple fixed factor clock
 * @node:       device node for the clock
 */
void __init of_fixed_factor_clk_setup(struct device_node *node)
{
        _of_fixed_factor_clk_setup(node);
}
CLK_OF_DECLARE(fixed_factor_clk, "fixed-factor-clock",
                of_fixed_factor_clk_setup);

static int of_fixed_factor_clk_remove(struct platform_device *pdev)
{
        struct clk_hw *clk = platform_get_drvdata(pdev);

        of_clk_del_provider(pdev->dev.of_node);
        clk_hw_unregister_fixed_factor(clk);

        return 0;
}

static int of_fixed_factor_clk_probe(struct platform_device *pdev)
{
        struct clk_hw *clk;

        /*
         * This function is not executed when of_fixed_factor_clk_setup
         * succeeded.
         */
        clk = _of_fixed_factor_clk_setup(pdev->dev.of_node);
        if (IS_ERR(clk))
                return PTR_ERR(clk);

        platform_set_drvdata(pdev, clk);

        return 0;
}

static const struct of_device_id of_fixed_factor_clk_ids[] = {
        { .compatible = "fixed-factor-clock" },
        { }
};
MODULE_DEVICE_TABLE(of, of_fixed_factor_clk_ids);

static struct platform_driver of_fixed_factor_clk_driver = {
        .driver = {
                .name = "of_fixed_factor_clk",
                .of_match_table = of_fixed_factor_clk_ids,
        },
        .probe = of_fixed_factor_clk_probe,
        .remove = of_fixed_factor_clk_remove,
};
builtin_platform_driver(of_fixed_factor_clk_driver);
#endif