// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/*
 * SP7021 reset driver
 *
 * Copyright (C) Sunplus Technology Co., Ltd.
 *       All rights reserved.
 */

#include <linux/io.h>
#include <linux/init.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>
#include <linux/reboot.h>

/* HIWORD_MASK_REG BITS */
#define BITS_PER_HWM_REG        16

/* resets HW info: reg_index_shift */
static const u32 sp_resets[] = {
/* SP7021: mo_reset0 ~ mo_reset9 */
        0x00,
        0x02,
        0x03,
        0x04,
        0x05,
        0x06,
        0x07,
        0x08,
        0x09,
        0x0a,
        0x0b,
        0x0d,
        0x0e,
        0x0f,
        0x10,
        0x12,
        0x14,
        0x15,
        0x16,
        0x17,
        0x18,
        0x19,
        0x1a,
        0x1b,
        0x1c,
        0x1d,
        0x1e,
        0x1f,
        0x20,
        0x21,
        0x22,
        0x23,
        0x24,
        0x25,
        0x26,
        0x2a,
        0x2b,
        0x2d,
        0x2e,
        0x30,
        0x31,
        0x32,
        0x33,
        0x3d,
        0x3e,
        0x3f,
        0x42,
        0x44,
        0x4b,
        0x4c,
        0x4d,
        0x4e,
        0x4f,
        0x50,
        0x55,
        0x60,
        0x61,
        0x6a,
        0x6f,
        0x70,
        0x73,
        0x74,
        0x86,
        0x8a,
        0x8b,
        0x8d,
        0x8e,
        0x8f,
        0x90,
        0x92,
        0x93,
        0x94,
        0x95,
        0x96,
        0x97,
        0x98,
        0x99,
};

struct sp_reset {
        struct reset_controller_dev rcdev;
        struct notifier_block notifier;
        void __iomem *base;
};

static inline struct sp_reset *to_sp_reset(struct reset_controller_dev *rcdev)
{
        return container_of(rcdev, struct sp_reset, rcdev);
}

static int sp_reset_update(struct reset_controller_dev *rcdev,
                           unsigned long id, bool assert)
{
        struct sp_reset *reset = to_sp_reset(rcdev);
        int index = sp_resets[id] / BITS_PER_HWM_REG;
        int shift = sp_resets[id] % BITS_PER_HWM_REG;
        u32 val;

        val = (1 << (16 + shift)) | (assert << shift);
        writel(val, reset->base + (index * 4));

        return 0;
}

static int sp_reset_assert(struct reset_controller_dev *rcdev,
                           unsigned long id)
{
        return sp_reset_update(rcdev, id, true);
}

static int sp_reset_deassert(struct reset_controller_dev *rcdev,
                             unsigned long id)
{
        return sp_reset_update(rcdev, id, false);
}

static int sp_reset_status(struct reset_controller_dev *rcdev,
                           unsigned long id)
{
        struct sp_reset *reset = to_sp_reset(rcdev);
        int index = sp_resets[id] / BITS_PER_HWM_REG;
        int shift = sp_resets[id] % BITS_PER_HWM_REG;
        u32 reg;

        reg = readl(reset->base + (index * 4));

        return !!(reg & BIT(shift));
}

static const struct reset_control_ops sp_reset_ops = {
        .assert   = sp_reset_assert,
        .deassert = sp_reset_deassert,
        .status   = sp_reset_status,
};

static int sp_restart(struct notifier_block *nb, unsigned long mode,
                      void *cmd)
{
        struct sp_reset *reset = container_of(nb, struct sp_reset, notifier);

        sp_reset_assert(&reset->rcdev, 0);
        sp_reset_deassert(&reset->rcdev, 0);

        return NOTIFY_DONE;
}

static int sp_reset_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct sp_reset *reset;
        struct resource *res;
        int ret;

        reset = devm_kzalloc(dev, sizeof(*reset), GFP_KERNEL);
        if (!reset)
                return -ENOMEM;

        reset->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
        if (IS_ERR(reset->base))
                return PTR_ERR(reset->base);

        reset->rcdev.ops = &sp_reset_ops;
        reset->rcdev.owner = THIS_MODULE;
        reset->rcdev.of_node = dev->of_node;
        reset->rcdev.nr_resets = resource_size(res) / 4 * BITS_PER_HWM_REG;

        ret = devm_reset_controller_register(dev, &reset->rcdev);
        if (ret)
                return ret;

        reset->notifier.notifier_call = sp_restart;
        reset->notifier.priority = 192;

        return register_restart_handler(&reset->notifier);
}

static const struct of_device_id sp_reset_dt_ids[] = {
        {.compatible = "sunplus,sp7021-reset",},
        { /* sentinel */ },
};

static struct platform_driver sp_reset_driver = {
        .probe = sp_reset_probe,
        .driver = {
                .name                   = "sunplus-reset",
                .of_match_table         = sp_reset_dt_ids,
                .suppress_bind_attrs    = true,
        },
};
builtin_platform_driver(sp_reset_driver);