// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2025 MediaTek Corporation. All rights reserved.
 * Author: Jjian Zhou <jjian.zhou.@mediatek.com>
 */

#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mailbox_controller.h>
#include <linux/mailbox/mtk-vcp-mailbox.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

struct mtk_vcp_mbox {
        struct mbox_controller mbox;
        void __iomem *base;
        struct device *dev;
        const struct mtk_vcp_mbox_cfg *cfg;
        struct mtk_ipi_info ipi_recv;
        struct mbox_chan chans;
};

struct mtk_vcp_mbox_cfg {
        u16 set_in;
        u16 clr_out;
};

static irqreturn_t mtk_vcp_mbox_irq_thread(int irq, void *data)
{
        struct mtk_vcp_mbox *priv = data;

        /* get irq status */
        priv->ipi_recv.irq_status = readl(priv->base + priv->cfg->clr_out);

        __ioread32_copy(priv->ipi_recv.msg, priv->base,
                        MTK_VCP_MBOX_SLOT_MAX_SIZE / 4);

        mbox_chan_received_data(&priv->chans, &priv->ipi_recv);

        /* clear irq status */
        writel(priv->ipi_recv.irq_status, priv->base + priv->cfg->clr_out);

        return IRQ_HANDLED;
}

static struct mbox_chan *mtk_vcp_mbox_xlate(struct mbox_controller *mbox,
                                            const struct of_phandle_args *sp)
{
        if (sp->args_count)
                return NULL;

        return &mbox->chans[0];
}

static int mtk_vcp_mbox_send_data(struct mbox_chan *chan, void *data)
{
        struct mtk_vcp_mbox *priv = chan->con_priv;
        struct mtk_ipi_info *ipi_info = data;
        u32 status;

        if (!ipi_info->msg) {
                dev_err(priv->dev, "msg buffer is NULL.\n");
                return -EINVAL;
        }

        status = readl(priv->base + priv->cfg->set_in);
        if (status & BIT(ipi_info->index)) {
                dev_warn(priv->dev, "mailbox IPI %d is busy.\n", ipi_info->id);
                return -EBUSY;
        }

        if (ipi_info->slot_ofs + ipi_info->len > MTK_VCP_MBOX_SLOT_MAX_SIZE)
                return -EINVAL;
        __iowrite32_copy(priv->base + ipi_info->slot_ofs, ipi_info->msg,
                         ipi_info->len);

        writel(BIT(ipi_info->index), priv->base + priv->cfg->set_in);

        return 0;
}

static bool mtk_vcp_mbox_last_tx_done(struct mbox_chan *chan)
{
        struct mtk_ipi_info *ipi_info = chan->active_req;
        struct mtk_vcp_mbox *priv = chan->con_priv;

        return !(readl(priv->base + priv->cfg->set_in) & BIT(ipi_info->index));
}

static const struct mbox_chan_ops mtk_vcp_mbox_chan_ops = {
        .send_data      = mtk_vcp_mbox_send_data,
        .last_tx_done   = mtk_vcp_mbox_last_tx_done,
};

static int mtk_vcp_mbox_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct mtk_vcp_mbox *priv;
        struct mbox_controller *mbox;
        int ret, irq;

        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->dev = dev;
        priv->chans.con_priv = priv;
        mbox = &priv->mbox;
        mbox->dev = dev;
        mbox->ops = &mtk_vcp_mbox_chan_ops;
        mbox->txdone_irq = false;
        mbox->txdone_poll = true;
        mbox->of_xlate = mtk_vcp_mbox_xlate;
        mbox->num_chans = 1;
        mbox->chans = &priv->chans;

        priv->ipi_recv.msg = devm_kzalloc(dev, MTK_VCP_MBOX_SLOT_MAX_SIZE,
                                          GFP_KERNEL);
        if (!priv->ipi_recv.msg)
                return -ENOMEM;

        priv->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(priv->base))
                return PTR_ERR(priv->base);

        priv->cfg = of_device_get_match_data(dev);
        if (!priv->cfg)
                return -EINVAL;

        platform_set_drvdata(pdev, priv);

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        ret = devm_request_threaded_irq(dev, irq, NULL,
                                        mtk_vcp_mbox_irq_thread, IRQF_ONESHOT,
                                        dev_name(dev), priv);
        if (ret < 0)
                return ret;

        return devm_mbox_controller_register(dev, &priv->mbox);
}

static const struct mtk_vcp_mbox_cfg mt8196_cfg = {
        .set_in         = 0x100,
        .clr_out        = 0x10c,
};

static const struct of_device_id mtk_vcp_mbox_of_match[] = {
        { .compatible = "mediatek,mt8196-vcp-mbox", .data = &mt8196_cfg },
        {},
};
MODULE_DEVICE_TABLE(of, mtk_vcp_mbox_of_match);

static struct platform_driver mtk_vcp_mbox_driver = {
        .probe          = mtk_vcp_mbox_probe,
        .driver = {
                .name   = "mtk_vcp_mbox",
                .of_match_table = mtk_vcp_mbox_of_match,
        },
};
module_platform_driver(mtk_vcp_mbox_driver);

MODULE_AUTHOR("Jjian Zhou <jjian.zhou@mediatek.com>");
MODULE_DESCRIPTION("MTK VCP Mailbox Controller");
MODULE_LICENSE("GPL");