// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Generic Syscon Reboot Driver
 *
 * Copyright (c) 2013, Applied Micro Circuits Corporation
 * Author: Feng Kan <fkan@apm.com>
 */
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/notifier.h>
#include <linux/mfd/syscon.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/reboot.h>
#include <linux/regmap.h>

struct reboot_mode_bits {
        u32 offset;
        u32 mask;
        u32 value;
        bool valid;
};

struct reboot_data {
        struct reboot_mode_bits mode_bits[REBOOT_SOFT + 1];
        struct reboot_mode_bits catchall;
};

struct syscon_reboot_context {
        struct regmap *map;

        const struct reboot_data *rd; /* from of match data, if any */
        struct reboot_mode_bits catchall; /* from DT */

        struct notifier_block restart_handler;
};

static int syscon_restart_handle(struct notifier_block *this,
                                        unsigned long mode, void *cmd)
{
        struct syscon_reboot_context *ctx =
                        container_of(this, struct syscon_reboot_context,
                                        restart_handler);
        const struct reboot_mode_bits *mode_bits;

        if (ctx->rd) {
                if (mode < ARRAY_SIZE(ctx->rd->mode_bits) &&
                    ctx->rd->mode_bits[mode].valid)
                        mode_bits = &ctx->rd->mode_bits[mode];
                else
                        mode_bits = &ctx->rd->catchall;
        } else {
                mode_bits = &ctx->catchall;
        }

        /* Issue the reboot */
        regmap_update_bits(ctx->map, mode_bits->offset, mode_bits->mask,
                           mode_bits->value);

        mdelay(1000);

        pr_emerg("Unable to restart system\n");
        return NOTIFY_DONE;
}

static int syscon_reboot_probe(struct platform_device *pdev)
{
        struct syscon_reboot_context *ctx;
        struct device *dev = &pdev->dev;
        int priority;
        int err;

        ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
        if (!ctx)
                return -ENOMEM;

        ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
        if (IS_ERR(ctx->map)) {
                ctx->map = syscon_node_to_regmap(dev->parent->of_node);
                if (IS_ERR(ctx->map))
                        return PTR_ERR(ctx->map);
        }

        if (of_property_read_s32(pdev->dev.of_node, "priority", &priority))
                priority = 192;

        ctx->rd = of_device_get_match_data(dev);
        if (!ctx->rd) {
                int mask_err, value_err;

                if (of_property_read_u32(pdev->dev.of_node, "offset",
                                         &ctx->catchall.offset) &&
                    of_property_read_u32(pdev->dev.of_node, "reg",
                                         &ctx->catchall.offset))
                        return -EINVAL;

                value_err = of_property_read_u32(pdev->dev.of_node, "value",
                                                 &ctx->catchall.value);
                mask_err = of_property_read_u32(pdev->dev.of_node, "mask",
                                                &ctx->catchall.mask);
                if (value_err && mask_err) {
                        dev_err(dev, "unable to read 'value' and 'mask'");
                        return -EINVAL;
                }

                if (value_err) {
                        /* support old binding */
                        ctx->catchall.value = ctx->catchall.mask;
                        ctx->catchall.mask = 0xFFFFFFFF;
                } else if (mask_err) {
                        /* support value without mask */
                        ctx->catchall.mask = 0xFFFFFFFF;
                }
        }

        ctx->restart_handler.notifier_call = syscon_restart_handle;
        ctx->restart_handler.priority = priority;
        err = register_restart_handler(&ctx->restart_handler);
        if (err)
                dev_err(dev, "can't register restart notifier (err=%d)\n", err);

        return err;
}

static const struct reboot_data gs101_reboot_data = {
        .mode_bits = {
                [REBOOT_WARM] = {
                        .offset = 0x3a00, /* SYSTEM_CONFIGURATION */
                        .mask = 0x00000002, /* SWRESET_SYSTEM */
                        .value = 0x00000002,
                        .valid = true,
                },
                [REBOOT_SOFT] = {
                        .offset = 0x3a00, /* SYSTEM_CONFIGURATION */
                        .mask = 0x00000002, /* SWRESET_SYSTEM */
                        .value = 0x00000002,
                        .valid = true,
                },
        },
        .catchall = {
                .offset = 0x3e9c, /* PAD_CTRL_PWR_HOLD */
                .mask = 0x00000100,
                .value = 0x00000000,
        },
};

static const struct of_device_id syscon_reboot_of_match[] = {
        { .compatible = "google,gs101-reboot", .data = &gs101_reboot_data  },
        { .compatible = "syscon-reboot" },
        {}
};

static struct platform_driver syscon_reboot_driver = {
        .probe = syscon_reboot_probe,
        .driver = {
                .name = "syscon-reboot",
                .of_match_table = syscon_reboot_of_match,
        },
};
builtin_platform_driver(syscon_reboot_driver);