// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2014 STMicroelectronics
 *
 * Power off Restart driver, used in STMicroelectronics devices.
 *
 * Author: Christophe Kerello <christophe.kerello@st.com>
 */

#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/mfd/syscon.h>
#include <linux/reboot.h>
#include <linux/regmap.h>

struct reset_syscfg {
        struct regmap *regmap;
        /* syscfg used for reset */
        unsigned int offset_rst;
        unsigned int mask_rst;
        /* syscfg used for unmask the reset */
        unsigned int offset_rst_msk;
        unsigned int mask_rst_msk;
};

/* STiH407 */
#define STIH407_SYSCFG_4000     0x0
#define STIH407_SYSCFG_4008     0x20

static struct reset_syscfg stih407_reset = {
        .offset_rst = STIH407_SYSCFG_4000,
        .mask_rst = BIT(0),
        .offset_rst_msk = STIH407_SYSCFG_4008,
        .mask_rst_msk = BIT(0)
};


static struct reset_syscfg *st_restart_syscfg;

static int st_restart(struct notifier_block *this, unsigned long mode,
                      void *cmd)
{
        /* reset syscfg updated */
        regmap_update_bits(st_restart_syscfg->regmap,
                           st_restart_syscfg->offset_rst,
                           st_restart_syscfg->mask_rst,
                           0);

        /* unmask the reset */
        regmap_update_bits(st_restart_syscfg->regmap,
                           st_restart_syscfg->offset_rst_msk,
                           st_restart_syscfg->mask_rst_msk,
                           0);

        return NOTIFY_DONE;
}

static struct notifier_block st_restart_nb = {
        .notifier_call = st_restart,
        .priority = 192,
};

static const struct of_device_id st_reset_of_match[] = {
        {
                .compatible = "st,stih407-restart",
                .data = (void *)&stih407_reset,
        },
        {}
};

static int st_reset_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        const struct of_device_id *match;
        struct device *dev = &pdev->dev;

        match = of_match_device(st_reset_of_match, dev);
        if (!match)
                return -ENODEV;

        st_restart_syscfg = (struct reset_syscfg *)match->data;

        st_restart_syscfg->regmap =
                syscon_regmap_lookup_by_phandle(np, "st,syscfg");
        if (IS_ERR(st_restart_syscfg->regmap)) {
                dev_err(dev, "No syscfg phandle specified\n");
                return PTR_ERR(st_restart_syscfg->regmap);
        }

        return register_restart_handler(&st_restart_nb);
}

static struct platform_driver st_reset_driver = {
        .probe = st_reset_probe,
        .driver = {
                .name = "st_reset",
                .of_match_table = st_reset_of_match,
        },
};

builtin_platform_driver(st_reset_driver);

MODULE_AUTHOR("Christophe Kerello <christophe.kerello@st.com>");
MODULE_DESCRIPTION("STMicroelectronics Power off Restart driver");
MODULE_LICENSE("GPL v2");