// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2013-2015 Fujitsu Semiconductor Ltd.
 * Copyright (C) 2015 Linaro Ltd.
 * Author: Jassi Brar <jaswinder.singh@linaro.org>
 */

#include <linux/amba/bus.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/mailbox_controller.h>
#include <linux/module.h>
#include <linux/of.h>

#define INTR_STAT_OFS   0x0
#define INTR_SET_OFS    0x8
#define INTR_CLR_OFS    0x10

#define MHU_LP_OFFSET   0x0
#define MHU_HP_OFFSET   0x20
#define MHU_SEC_OFFSET  0x200
#define TX_REG_OFFSET   0x100

#define MHU_CHANS       3

struct mhu_link {
        unsigned irq;
        void __iomem *tx_reg;
        void __iomem *rx_reg;
};

struct arm_mhu {
        void __iomem *base;
        struct mhu_link mlink[MHU_CHANS];
        struct mbox_chan chan[MHU_CHANS];
        struct mbox_controller mbox;
};

static irqreturn_t mhu_rx_interrupt(int irq, void *p)
{
        struct mbox_chan *chan = p;
        struct mhu_link *mlink = chan->con_priv;
        u32 val;

        val = readl_relaxed(mlink->rx_reg + INTR_STAT_OFS);
        if (!val)
                return IRQ_NONE;

        mbox_chan_received_data(chan, (void *)&val);

        writel_relaxed(val, mlink->rx_reg + INTR_CLR_OFS);

        return IRQ_HANDLED;
}

static bool mhu_last_tx_done(struct mbox_chan *chan)
{
        struct mhu_link *mlink = chan->con_priv;
        u32 val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);

        return (val == 0);
}

static int mhu_send_data(struct mbox_chan *chan, void *data)
{
        struct mhu_link *mlink = chan->con_priv;
        u32 *arg = data;

        writel_relaxed(*arg, mlink->tx_reg + INTR_SET_OFS);

        return 0;
}

static int mhu_startup(struct mbox_chan *chan)
{
        struct mhu_link *mlink = chan->con_priv;
        u32 val;
        int ret;

        val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
        writel_relaxed(val, mlink->tx_reg + INTR_CLR_OFS);

        ret = request_irq(mlink->irq, mhu_rx_interrupt,
                          IRQF_SHARED, "mhu_link", chan);
        if (ret) {
                dev_err(chan->mbox->dev,
                        "Unable to acquire IRQ %d\n", mlink->irq);
                return ret;
        }

        return 0;
}

static void mhu_shutdown(struct mbox_chan *chan)
{
        struct mhu_link *mlink = chan->con_priv;

        free_irq(mlink->irq, chan);
}

static const struct mbox_chan_ops mhu_ops = {
        .send_data = mhu_send_data,
        .startup = mhu_startup,
        .shutdown = mhu_shutdown,
        .last_tx_done = mhu_last_tx_done,
};

static int mhu_probe(struct amba_device *adev, const struct amba_id *id)
{
        int i, err;
        struct arm_mhu *mhu;
        struct device *dev = &adev->dev;
        int mhu_reg[MHU_CHANS] = {MHU_LP_OFFSET, MHU_HP_OFFSET, MHU_SEC_OFFSET};

        if (!of_device_is_compatible(dev->of_node, "arm,mhu"))
                return -ENODEV;

        /* Allocate memory for device */
        mhu = devm_kzalloc(dev, sizeof(*mhu), GFP_KERNEL);
        if (!mhu)
                return -ENOMEM;

        mhu->base = devm_ioremap_resource(dev, &adev->res);
        if (IS_ERR(mhu->base))
                return PTR_ERR(mhu->base);

        for (i = 0; i < MHU_CHANS; i++) {
                mhu->chan[i].con_priv = &mhu->mlink[i];
                mhu->mlink[i].irq = adev->irq[i];
                mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];
                mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;
        }

        mhu->mbox.dev = dev;
        mhu->mbox.chans = &mhu->chan[0];
        mhu->mbox.num_chans = MHU_CHANS;
        mhu->mbox.ops = &mhu_ops;
        mhu->mbox.txdone_irq = false;
        mhu->mbox.txdone_poll = true;
        mhu->mbox.txpoll_period = 1;

        amba_set_drvdata(adev, mhu);

        err = devm_mbox_controller_register(dev, &mhu->mbox);
        if (err) {
                dev_err(dev, "Failed to register mailboxes %d\n", err);
                return err;
        }

        dev_info(dev, "ARM MHU Mailbox registered\n");
        return 0;
}

static const struct amba_id mhu_ids[] = {
        {
                .id     = 0x1bb098,
                .mask   = 0xffffff,
        },
        { 0, 0 },
};
MODULE_DEVICE_TABLE(amba, mhu_ids);

static struct amba_driver arm_mhu_driver = {
        .drv = {
                .name   = "mhu",
        },
        .id_table       = mhu_ids,
        .probe          = mhu_probe,
};
module_amba_driver(arm_mhu_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("ARM MHU Driver");
MODULE_AUTHOR("Jassi Brar <jassisinghbrar@gmail.com>");