// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2016 BayLibre SAS.
 * Author: Neil Armstrong <narmstrong@baylibre.com>
 * Synchronised with arm_mhu.c from :
 * Copyright (C) 2013-2015 Fujitsu Semiconductor Ltd.
 * Copyright (C) 2015 Linaro Ltd.
 * Author: Jassi Brar <jaswinder.singh@linaro.org>
 */

#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/mailbox_controller.h>

#define INTR_SET_OFS    0x0
#define INTR_STAT_OFS   0x4
#define INTR_CLR_OFS    0x8

#define MHU_SEC_OFFSET  0x0
#define MHU_LP_OFFSET   0xc
#define MHU_HP_OFFSET   0x18
#define TX_REG_OFFSET   0x24

#define MHU_CHANS       3

struct platform_mhu_link {
        int irq;
        void __iomem *tx_reg;
        void __iomem *rx_reg;
};

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

static irqreturn_t platform_mhu_rx_interrupt(int irq, void *p)
{
        struct mbox_chan *chan = p;
        struct platform_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 platform_mhu_last_tx_done(struct mbox_chan *chan)
{
        struct platform_mhu_link *mlink = chan->con_priv;
        u32 val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);

        return (val == 0);
}

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

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

        return 0;
}

static int platform_mhu_startup(struct mbox_chan *chan)
{
        struct platform_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, platform_mhu_rx_interrupt,
                          IRQF_SHARED, "platform_mhu_link", chan);
        if (ret) {
                dev_err(chan->mbox->dev,
                        "Unable to acquire IRQ %d\n", mlink->irq);
                return ret;
        }

        return 0;
}

static void platform_mhu_shutdown(struct mbox_chan *chan)
{
        struct platform_mhu_link *mlink = chan->con_priv;

        free_irq(mlink->irq, chan);
}

static const struct mbox_chan_ops platform_mhu_ops = {
        .send_data = platform_mhu_send_data,
        .startup = platform_mhu_startup,
        .shutdown = platform_mhu_shutdown,
        .last_tx_done = platform_mhu_last_tx_done,
};

static int platform_mhu_probe(struct platform_device *pdev)
{
        int i, err;
        struct platform_mhu *mhu;
        struct device *dev = &pdev->dev;
        int platform_mhu_reg[MHU_CHANS] = {
                MHU_SEC_OFFSET, MHU_LP_OFFSET, MHU_HP_OFFSET
        };

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

        mhu->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(mhu->base)) {
                dev_err(dev, "ioremap failed\n");
                return PTR_ERR(mhu->base);
        }

        for (i = 0; i < MHU_CHANS; i++) {
                mhu->chan[i].con_priv = &mhu->mlink[i];
                mhu->mlink[i].irq = platform_get_irq(pdev, i);
                if (mhu->mlink[i].irq < 0)
                        return mhu->mlink[i].irq;
                mhu->mlink[i].rx_reg = mhu->base + platform_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 = &platform_mhu_ops;
        mhu->mbox.txdone_irq = false;
        mhu->mbox.txdone_poll = true;
        mhu->mbox.txpoll_period = 1;

        platform_set_drvdata(pdev, 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, "Platform MHU Mailbox registered\n");
        return 0;
}

static const struct of_device_id platform_mhu_dt_ids[] = {
        { .compatible = "amlogic,meson-gxbb-mhu", },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, platform_mhu_dt_ids);

static struct platform_driver platform_mhu_driver = {
        .probe  = platform_mhu_probe,
        .driver = {
                .name = "platform-mhu",
                .of_match_table = platform_mhu_dt_ids,
        },
};

module_platform_driver(platform_mhu_driver);

MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:platform-mhu");
MODULE_DESCRIPTION("Platform MHU Driver");
MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");