// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 * Copyright (C) 2012 ARM Limited
 */

#include <linux/delay.h>
#include <linux/notifier.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/reboot.h>
#include <linux/stat.h>
#include <linux/vexpress.h>

static void vexpress_reset_do(struct device *dev, const char *what)
{
        int err = -ENOENT;
        struct regmap *reg = dev_get_drvdata(dev);

        if (reg) {
                err = regmap_write(reg, 0, 0);
                if (!err)
                        mdelay(1000);
        }

        dev_emerg(dev, "Unable to %s (%d)\n", what, err);
}

static struct device *vexpress_power_off_device;
static atomic_t vexpress_restart_nb_refcnt = ATOMIC_INIT(0);

static void vexpress_power_off(void)
{
        vexpress_reset_do(vexpress_power_off_device, "power off");
}

static struct device *vexpress_restart_device;

static int vexpress_restart(struct notifier_block *this, unsigned long mode,
                             void *cmd)
{
        vexpress_reset_do(vexpress_restart_device, "restart");

        return NOTIFY_DONE;
}

static struct notifier_block vexpress_restart_nb = {
        .notifier_call = vexpress_restart,
        .priority = 128,
};

static ssize_t vexpress_reset_active_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "%d\n", vexpress_restart_device == dev);
}

static ssize_t vexpress_reset_active_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t count)
{
        long value;
        int err = kstrtol(buf, 0, &value);

        if (!err && value)
                vexpress_restart_device = dev;

        return err ? err : count;
}

static DEVICE_ATTR(active, S_IRUGO | S_IWUSR, vexpress_reset_active_show,
                   vexpress_reset_active_store);


enum vexpress_reset_func { FUNC_RESET, FUNC_SHUTDOWN, FUNC_REBOOT };

static const struct of_device_id vexpress_reset_of_match[] = {
        {
                .compatible = "arm,vexpress-reset",
                .data = (void *)FUNC_RESET,
        }, {
                .compatible = "arm,vexpress-shutdown",
                .data = (void *)FUNC_SHUTDOWN
        }, {
                .compatible = "arm,vexpress-reboot",
                .data = (void *)FUNC_REBOOT
        },
        {}
};

static int _vexpress_register_restart_handler(struct device *dev)
{
        int err;

        vexpress_restart_device = dev;
        if (atomic_inc_return(&vexpress_restart_nb_refcnt) == 1) {
                err = register_restart_handler(&vexpress_restart_nb);
                if (err) {
                        dev_err(dev, "cannot register restart handler (err=%d)\n", err);
                        atomic_dec(&vexpress_restart_nb_refcnt);
                        return err;
                }
        }
        device_create_file(dev, &dev_attr_active);

        return 0;
}

static int vexpress_reset_probe(struct platform_device *pdev)
{
        enum vexpress_reset_func func;
        struct regmap *regmap;
        int ret = 0;

        regmap = devm_regmap_init_vexpress_config(&pdev->dev);
        if (IS_ERR(regmap))
                return PTR_ERR(regmap);
        dev_set_drvdata(&pdev->dev, regmap);

        func = (uintptr_t)device_get_match_data(&pdev->dev);
        switch (func) {
        case FUNC_SHUTDOWN:
                vexpress_power_off_device = &pdev->dev;
                pm_power_off = vexpress_power_off;
                break;
        case FUNC_RESET:
                if (!vexpress_restart_device)
                        ret = _vexpress_register_restart_handler(&pdev->dev);
                break;
        case FUNC_REBOOT:
                ret = _vexpress_register_restart_handler(&pdev->dev);
                break;
        }

        return ret;
}

static struct platform_driver vexpress_reset_driver = {
        .probe = vexpress_reset_probe,
        .driver = {
                .name = "vexpress-reset",
                .of_match_table = vexpress_reset_of_match,
                .suppress_bind_attrs = true,
        },
};
builtin_platform_driver(vexpress_reset_driver);