// SPDX-License-Identifier: GPL-2.0-only
/*
 * HiSilicon SoC reset code
 *
 * Copyright (c) 2014 HiSilicon Ltd.
 * Copyright (c) 2014 Linaro Ltd.
 *
 * Author: Haojian Zhuang <haojian.zhuang@linaro.org>
 */

#include <linux/delay.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/reboot.h>

#include <asm/proc-fns.h>

static void __iomem *base;
static u32 reboot_offset;

static int hisi_restart_handler(struct notifier_block *this,
                                unsigned long mode, void *cmd)
{
        writel_relaxed(0xdeadbeef, base + reboot_offset);

        while (1)
                cpu_do_idle();

        return NOTIFY_DONE;
}

static struct notifier_block hisi_restart_nb = {
        .notifier_call = hisi_restart_handler,
        .priority = 128,
};

static int hisi_reboot_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        int err;

        base = of_iomap(np, 0);
        if (!base) {
                WARN(1, "failed to map base address");
                return -ENODEV;
        }

        if (of_property_read_u32(np, "reboot-offset", &reboot_offset) < 0) {
                pr_err("failed to find reboot-offset property\n");
                iounmap(base);
                return -EINVAL;
        }

        err = register_restart_handler(&hisi_restart_nb);
        if (err) {
                dev_err(&pdev->dev, "cannot register restart handler (err=%d)\n",
                        err);
                iounmap(base);
        }

        return err;
}

static const struct of_device_id hisi_reboot_of_match[] = {
        { .compatible = "hisilicon,sysctrl" },
        {}
};
MODULE_DEVICE_TABLE(of, hisi_reboot_of_match);

static struct platform_driver hisi_reboot_driver = {
        .probe = hisi_reboot_probe,
        .driver = {
                .name = "hisi-reboot",
                .of_match_table = hisi_reboot_of_match,
        },
};
module_platform_driver(hisi_reboot_driver);