// SPDX-License-Identifier: GPL-2.0-only
/*
 * Reset driver for Axxia devices
 *
 * Copyright (C) 2014 LSI
 */
#include <linux/init.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/reboot.h>
#include <linux/regmap.h>

#define SC_CRIT_WRITE_KEY       0x1000
#define SC_LATCH_ON_RESET       0x1004
#define SC_RESET_CONTROL        0x1008
#define   RSTCTL_RST_ZERO       (1<<3)
#define   RSTCTL_RST_FAB        (1<<2)
#define   RSTCTL_RST_CHIP       (1<<1)
#define   RSTCTL_RST_SYS        (1<<0)
#define SC_EFUSE_INT_STATUS     0x180c
#define   EFUSE_READ_DONE       (1<<31)

static int axxia_restart_handler(struct sys_off_data *data)
{
        struct regmap *syscon = data->cb_data;

        /* Access Key (0xab) */
        regmap_write(syscon, SC_CRIT_WRITE_KEY, 0xab);
        /* Select internal boot from 0xffff0000 */
        regmap_write(syscon, SC_LATCH_ON_RESET, 0x00000040);
        /* Assert ResetReadDone (to avoid hanging in boot ROM) */
        regmap_write(syscon, SC_EFUSE_INT_STATUS, EFUSE_READ_DONE);
        /* Assert chip reset */
        regmap_update_bits(syscon, SC_RESET_CONTROL,
                           RSTCTL_RST_CHIP, RSTCTL_RST_CHIP);

        return NOTIFY_DONE;
}

static int axxia_reset_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct regmap *syscon;
        int err;

        syscon = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
        if (IS_ERR(syscon)) {
                pr_err("%pOFn: syscon lookup failed\n", dev->of_node);
                return PTR_ERR(syscon);
        }

        err = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_RESTART,
                                            128, axxia_restart_handler, syscon);
        if (err)
                dev_err(dev, "cannot register restart handler (err=%d)\n", err);

        return err;
}

static const struct of_device_id of_axxia_reset_match[] = {
        { .compatible = "lsi,axm55xx-reset", },
        {},
};
MODULE_DEVICE_TABLE(of, of_axxia_reset_match);

static struct platform_driver axxia_reset_driver = {
        .probe = axxia_reset_probe,
        .driver = {
                .name = "axxia-reset",
                .of_match_table = of_match_ptr(of_axxia_reset_match),
        },
};
builtin_platform_driver(axxia_reset_driver);