// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright Altera Corporation (C) 2013-2014. All rights reserved
 */

#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mailbox_controller.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>

#define DRIVER_NAME     "altera-mailbox"

#define MAILBOX_CMD_REG                 0x00
#define MAILBOX_PTR_REG                 0x04
#define MAILBOX_STS_REG                 0x08
#define MAILBOX_INTMASK_REG             0x0C

#define INT_PENDING_MSK                 0x1
#define INT_SPACE_MSK                   0x2

#define STS_PENDING_MSK                 0x1
#define STS_FULL_MSK                    0x2
#define STS_FULL_OFT                    0x1

#define MBOX_PENDING(status)    (((status) & STS_PENDING_MSK))
#define MBOX_FULL(status)       (((status) & STS_FULL_MSK) >> STS_FULL_OFT)

enum altera_mbox_msg {
        MBOX_CMD = 0,
        MBOX_PTR,
};

#define MBOX_POLLING_MS         5       /* polling interval 5ms */

struct altera_mbox {
        bool is_sender;         /* 1-sender, 0-receiver */
        bool intr_mode;
        int irq;
        void __iomem *mbox_base;
        struct device *dev;
        struct mbox_controller controller;

        /* If the controller supports only RX polling mode */
        struct timer_list rxpoll_timer;
        struct mbox_chan *chan;
};

static struct altera_mbox *mbox_chan_to_altera_mbox(struct mbox_chan *chan)
{
        if (!chan || !chan->con_priv)
                return NULL;

        return (struct altera_mbox *)chan->con_priv;
}

static inline int altera_mbox_full(struct altera_mbox *mbox)
{
        u32 status;

        status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);
        return MBOX_FULL(status);
}

static inline int altera_mbox_pending(struct altera_mbox *mbox)
{
        u32 status;

        status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);
        return MBOX_PENDING(status);
}

static void altera_mbox_rx_intmask(struct altera_mbox *mbox, bool enable)
{
        u32 mask;

        mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
        if (enable)
                mask |= INT_PENDING_MSK;
        else
                mask &= ~INT_PENDING_MSK;
        writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
}

static void altera_mbox_tx_intmask(struct altera_mbox *mbox, bool enable)
{
        u32 mask;

        mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
        if (enable)
                mask |= INT_SPACE_MSK;
        else
                mask &= ~INT_SPACE_MSK;
        writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
}

static bool altera_mbox_is_sender(struct altera_mbox *mbox)
{
        u32 reg;
        /* Write a magic number to PTR register and read back this register.
         * This register is read-write if it is a sender.
         */
        #define MBOX_MAGIC      0xA5A5AA55
        writel_relaxed(MBOX_MAGIC, mbox->mbox_base + MAILBOX_PTR_REG);
        reg = readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);
        if (reg == MBOX_MAGIC) {
                /* Clear to 0 */
                writel_relaxed(0, mbox->mbox_base + MAILBOX_PTR_REG);
                return true;
        }
        return false;
}

static void altera_mbox_rx_data(struct mbox_chan *chan)
{
        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
        u32 data[2];

        if (altera_mbox_pending(mbox)) {
                data[MBOX_PTR] =
                        readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);
                data[MBOX_CMD] =
                        readl_relaxed(mbox->mbox_base + MAILBOX_CMD_REG);
                mbox_chan_received_data(chan, (void *)data);
        }
}

static void altera_mbox_poll_rx(struct timer_list *t)
{
        struct altera_mbox *mbox = timer_container_of(mbox, t, rxpoll_timer);

        altera_mbox_rx_data(mbox->chan);

        mod_timer(&mbox->rxpoll_timer,
                  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
}

static irqreturn_t altera_mbox_tx_interrupt(int irq, void *p)
{
        struct mbox_chan *chan = (struct mbox_chan *)p;
        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);

        altera_mbox_tx_intmask(mbox, false);
        mbox_chan_txdone(chan, 0);

        return IRQ_HANDLED;
}

static irqreturn_t altera_mbox_rx_interrupt(int irq, void *p)
{
        struct mbox_chan *chan = (struct mbox_chan *)p;

        altera_mbox_rx_data(chan);
        return IRQ_HANDLED;
}

static int altera_mbox_startup_sender(struct mbox_chan *chan)
{
        int ret;
        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);

        if (mbox->intr_mode) {
                ret = request_irq(mbox->irq, altera_mbox_tx_interrupt, 0,
                                  DRIVER_NAME, chan);
                if (unlikely(ret)) {
                        dev_err(mbox->dev,
                                "failed to register mailbox interrupt:%d\n",
                                ret);
                        return ret;
                }
        }

        return 0;
}

static int altera_mbox_startup_receiver(struct mbox_chan *chan)
{
        int ret;
        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);

        if (mbox->intr_mode) {
                ret = request_irq(mbox->irq, altera_mbox_rx_interrupt, 0,
                                  DRIVER_NAME, chan);
                if (unlikely(ret)) {
                        mbox->intr_mode = false;
                        goto polling; /* use polling if failed */
                }

                altera_mbox_rx_intmask(mbox, true);
                return 0;
        }

polling:
        /* Setup polling timer */
        mbox->chan = chan;
        timer_setup(&mbox->rxpoll_timer, altera_mbox_poll_rx, 0);
        mod_timer(&mbox->rxpoll_timer,
                  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));

        return 0;
}

static int altera_mbox_send_data(struct mbox_chan *chan, void *data)
{
        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
        u32 *udata = (u32 *)data;

        if (!mbox || !data)
                return -EINVAL;
        if (!mbox->is_sender) {
                dev_warn(mbox->dev,
                         "failed to send. This is receiver mailbox.\n");
                return -EINVAL;
        }

        if (altera_mbox_full(mbox))
                return -EBUSY;

        /* Enable interrupt before send */
        if (mbox->intr_mode)
                altera_mbox_tx_intmask(mbox, true);

        /* Pointer register must write before command register */
        writel_relaxed(udata[MBOX_PTR], mbox->mbox_base + MAILBOX_PTR_REG);
        writel_relaxed(udata[MBOX_CMD], mbox->mbox_base + MAILBOX_CMD_REG);

        return 0;
}

static bool altera_mbox_last_tx_done(struct mbox_chan *chan)
{
        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);

        /* Return false if mailbox is full */
        return altera_mbox_full(mbox) ? false : true;
}

static bool altera_mbox_peek_data(struct mbox_chan *chan)
{
        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);

        return altera_mbox_pending(mbox) ? true : false;
}

static int altera_mbox_startup(struct mbox_chan *chan)
{
        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
        int ret = 0;

        if (!mbox)
                return -EINVAL;

        if (mbox->is_sender)
                ret = altera_mbox_startup_sender(chan);
        else
                ret = altera_mbox_startup_receiver(chan);

        return ret;
}

static void altera_mbox_shutdown(struct mbox_chan *chan)
{
        struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);

        if (mbox->intr_mode) {
                /* Unmask all interrupt masks */
                writel_relaxed(~0, mbox->mbox_base + MAILBOX_INTMASK_REG);
                free_irq(mbox->irq, chan);
        } else if (!mbox->is_sender) {
                timer_delete_sync(&mbox->rxpoll_timer);
        }
}

static const struct mbox_chan_ops altera_mbox_ops = {
        .send_data = altera_mbox_send_data,
        .startup = altera_mbox_startup,
        .shutdown = altera_mbox_shutdown,
        .last_tx_done = altera_mbox_last_tx_done,
        .peek_data = altera_mbox_peek_data,
};

static int altera_mbox_probe(struct platform_device *pdev)
{
        struct altera_mbox *mbox;
        struct mbox_chan *chans;
        int ret;

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

        /* Allocated one channel */
        chans = devm_kzalloc(&pdev->dev, sizeof(*chans), GFP_KERNEL);
        if (!chans)
                return -ENOMEM;

        mbox->mbox_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(mbox->mbox_base))
                return PTR_ERR(mbox->mbox_base);

        /* Check is it a sender or receiver? */
        mbox->is_sender = altera_mbox_is_sender(mbox);

        mbox->irq = platform_get_irq(pdev, 0);
        if (mbox->irq >= 0)
                mbox->intr_mode = true;

        mbox->dev = &pdev->dev;

        /* Hardware supports only one channel. */
        chans[0].con_priv = mbox;
        mbox->controller.dev = mbox->dev;
        mbox->controller.num_chans = 1;
        mbox->controller.chans = chans;
        mbox->controller.ops = &altera_mbox_ops;

        if (mbox->is_sender) {
                if (mbox->intr_mode) {
                        mbox->controller.txdone_irq = true;
                } else {
                        mbox->controller.txdone_poll = true;
                        mbox->controller.txpoll_period = MBOX_POLLING_MS;
                }
        }

        ret = devm_mbox_controller_register(&pdev->dev, &mbox->controller);
        if (ret) {
                dev_err(&pdev->dev, "Register mailbox failed\n");
                goto err;
        }

        platform_set_drvdata(pdev, mbox);
err:
        return ret;
}

static const struct of_device_id altera_mbox_match[] = {
        { .compatible = "altr,mailbox-1.0" },
        { /* Sentinel */ }
};

MODULE_DEVICE_TABLE(of, altera_mbox_match);

static struct platform_driver altera_mbox_driver = {
        .probe  = altera_mbox_probe,
        .driver = {
                .name   = DRIVER_NAME,
                .of_match_table = altera_mbox_match,
        },
};

module_platform_driver(altera_mbox_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Altera mailbox specific functions");
MODULE_AUTHOR("Ley Foon Tan <lftan@altera.com>");
MODULE_ALIAS("platform:altera-mailbox");