// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright 2015 Chen-Yu Tsai
 *
 * Chen-Yu Tsai <wens@csie.org>
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/reset.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#define SUN9I_MMC_WIDTH         4

#define SUN9I_MMC_GATE_BIT      16
#define SUN9I_MMC_RESET_BIT     18

struct sun9i_mmc_clk_data {
        spinlock_t                      lock;
        void __iomem                    *membase;
        struct clk                      *clk;
        struct reset_control            *reset;
        struct clk_onecell_data         clk_data;
        struct reset_controller_dev     rcdev;
};

static int sun9i_mmc_reset_assert(struct reset_controller_dev *rcdev,
                              unsigned long id)
{
        struct sun9i_mmc_clk_data *data = container_of(rcdev,
                                                       struct sun9i_mmc_clk_data,
                                                       rcdev);
        unsigned long flags;
        void __iomem *reg = data->membase + SUN9I_MMC_WIDTH * id;
        u32 val;

        clk_prepare_enable(data->clk);
        spin_lock_irqsave(&data->lock, flags);

        val = readl(reg);
        writel(val & ~BIT(SUN9I_MMC_RESET_BIT), reg);

        spin_unlock_irqrestore(&data->lock, flags);
        clk_disable_unprepare(data->clk);

        return 0;
}

static int sun9i_mmc_reset_deassert(struct reset_controller_dev *rcdev,
                                unsigned long id)
{
        struct sun9i_mmc_clk_data *data = container_of(rcdev,
                                                       struct sun9i_mmc_clk_data,
                                                       rcdev);
        unsigned long flags;
        void __iomem *reg = data->membase + SUN9I_MMC_WIDTH * id;
        u32 val;

        clk_prepare_enable(data->clk);
        spin_lock_irqsave(&data->lock, flags);

        val = readl(reg);
        writel(val | BIT(SUN9I_MMC_RESET_BIT), reg);

        spin_unlock_irqrestore(&data->lock, flags);
        clk_disable_unprepare(data->clk);

        return 0;
}

static int sun9i_mmc_reset_reset(struct reset_controller_dev *rcdev,
                                 unsigned long id)
{
        sun9i_mmc_reset_assert(rcdev, id);
        udelay(10);
        sun9i_mmc_reset_deassert(rcdev, id);

        return 0;
}

static const struct reset_control_ops sun9i_mmc_reset_ops = {
        .assert         = sun9i_mmc_reset_assert,
        .deassert       = sun9i_mmc_reset_deassert,
        .reset          = sun9i_mmc_reset_reset,
};

static int sun9i_a80_mmc_config_clk_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct sun9i_mmc_clk_data *data;
        struct clk_onecell_data *clk_data;
        const char *clk_name = np->name;
        const char *clk_parent;
        struct resource *r;
        int count, i, ret;

        data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        spin_lock_init(&data->lock);

        data->membase = devm_platform_get_and_ioremap_resource(pdev, 0, &r);
        if (IS_ERR(data->membase))
                return PTR_ERR(data->membase);

        /* one clock/reset pair per word */
        count = DIV_ROUND_UP((resource_size(r)), SUN9I_MMC_WIDTH);

        clk_data = &data->clk_data;
        clk_data->clk_num = count;
        clk_data->clks = devm_kcalloc(&pdev->dev, count, sizeof(struct clk *),
                                      GFP_KERNEL);
        if (!clk_data->clks)
                return -ENOMEM;

        data->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(data->clk)) {
                dev_err(&pdev->dev, "Could not get clock\n");
                return PTR_ERR(data->clk);
        }

        data->reset = devm_reset_control_get_exclusive(&pdev->dev, NULL);
        if (IS_ERR(data->reset)) {
                dev_err(&pdev->dev, "Could not get reset control\n");
                return PTR_ERR(data->reset);
        }

        ret = reset_control_deassert(data->reset);
        if (ret) {
                dev_err(&pdev->dev, "Reset deassert err %d\n", ret);
                return ret;
        }

        clk_parent = __clk_get_name(data->clk);
        for (i = 0; i < count; i++) {
                of_property_read_string_index(np, "clock-output-names",
                                              i, &clk_name);

                clk_data->clks[i] = clk_register_gate(&pdev->dev, clk_name,
                                                      clk_parent, 0,
                                                      data->membase + SUN9I_MMC_WIDTH * i,
                                                      SUN9I_MMC_GATE_BIT, 0,
                                                      &data->lock);

                if (IS_ERR(clk_data->clks[i])) {
                        ret = PTR_ERR(clk_data->clks[i]);
                        goto err_clk_register;
                }
        }

        ret = of_clk_add_provider(np, of_clk_src_onecell_get, clk_data);
        if (ret)
                goto err_clk_provider;

        data->rcdev.owner = THIS_MODULE;
        data->rcdev.nr_resets = count;
        data->rcdev.ops = &sun9i_mmc_reset_ops;
        data->rcdev.of_node = pdev->dev.of_node;

        ret = reset_controller_register(&data->rcdev);
        if (ret)
                goto err_rc_reg;

        platform_set_drvdata(pdev, data);

        return 0;

err_rc_reg:
        of_clk_del_provider(np);

err_clk_provider:
        for (i = 0; i < count; i++)
                clk_unregister(clk_data->clks[i]);

err_clk_register:
        reset_control_assert(data->reset);

        return ret;
}

static const struct of_device_id sun9i_a80_mmc_config_clk_dt_ids[] = {
        { .compatible = "allwinner,sun9i-a80-mmc-config-clk" },
        { /* sentinel */ }
};

static struct platform_driver sun9i_a80_mmc_config_clk_driver = {
        .driver = {
                .name = "sun9i-a80-mmc-config-clk",
                .suppress_bind_attrs = true,
                .of_match_table = sun9i_a80_mmc_config_clk_dt_ids,
        },
        .probe = sun9i_a80_mmc_config_clk_probe,
};
builtin_platform_driver(sun9i_a80_mmc_config_clk_driver);