// SPDX-License-Identifier: GPL-2.0-only
/*
 * Hisilicon's Hi6220 mailbox driver
 *
 * Copyright (c) 2015 HiSilicon Limited.
 * Copyright (c) 2015 Linaro Limited.
 *
 * Author: Leo Yan <leo.yan@linaro.org>
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kfifo.h>
#include <linux/mailbox_controller.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#define MBOX_CHAN_MAX                   32

#define MBOX_TX                         0x1

/* Mailbox message length: 8 words */
#define MBOX_MSG_LEN                    8

/* Mailbox Registers */
#define MBOX_OFF(m)                     (0x40 * (m))
#define MBOX_MODE_REG(m)                (MBOX_OFF(m) + 0x0)
#define MBOX_DATA_REG(m)                (MBOX_OFF(m) + 0x4)

#define MBOX_STATE_MASK                 (0xF << 4)
#define MBOX_STATE_IDLE                 (0x1 << 4)
#define MBOX_STATE_TX                   (0x2 << 4)
#define MBOX_STATE_RX                   (0x4 << 4)
#define MBOX_STATE_ACK                  (0x8 << 4)
#define MBOX_ACK_CONFIG_MASK            (0x1 << 0)
#define MBOX_ACK_AUTOMATIC              (0x1 << 0)
#define MBOX_ACK_IRQ                    (0x0 << 0)

/* IPC registers */
#define ACK_INT_RAW_REG(i)              ((i) + 0x400)
#define ACK_INT_MSK_REG(i)              ((i) + 0x404)
#define ACK_INT_STAT_REG(i)             ((i) + 0x408)
#define ACK_INT_CLR_REG(i)              ((i) + 0x40c)
#define ACK_INT_ENA_REG(i)              ((i) + 0x500)
#define ACK_INT_DIS_REG(i)              ((i) + 0x504)
#define DST_INT_RAW_REG(i)              ((i) + 0x420)


struct hi6220_mbox_chan {

        /*
         * Description for channel's hardware info:
         *  - direction: tx or rx
         *  - dst irq: peer core's irq number
         *  - ack irq: local irq number
         *  - slot number
         */
        unsigned int dir, dst_irq, ack_irq;
        unsigned int slot;

        struct hi6220_mbox *parent;
};

struct hi6220_mbox {
        struct device *dev;

        int irq;

        /* flag of enabling tx's irq mode */
        bool tx_irq_mode;

        /* region for ipc event */
        void __iomem *ipc;

        /* region for mailbox */
        void __iomem *base;

        unsigned int chan_num;
        struct hi6220_mbox_chan *mchan;

        void *irq_map_chan[MBOX_CHAN_MAX];
        struct mbox_chan *chan;
        struct mbox_controller controller;
};

static void mbox_set_state(struct hi6220_mbox *mbox,
                           unsigned int slot, u32 val)
{
        u32 status;

        status = readl(mbox->base + MBOX_MODE_REG(slot));
        status = (status & ~MBOX_STATE_MASK) | val;
        writel(status, mbox->base + MBOX_MODE_REG(slot));
}

static void mbox_set_mode(struct hi6220_mbox *mbox,
                          unsigned int slot, u32 val)
{
        u32 mode;

        mode = readl(mbox->base + MBOX_MODE_REG(slot));
        mode = (mode & ~MBOX_ACK_CONFIG_MASK) | val;
        writel(mode, mbox->base + MBOX_MODE_REG(slot));
}

static bool hi6220_mbox_last_tx_done(struct mbox_chan *chan)
{
        struct hi6220_mbox_chan *mchan = chan->con_priv;
        struct hi6220_mbox *mbox = mchan->parent;
        u32 state;

        /* Only set idle state for polling mode */
        BUG_ON(mbox->tx_irq_mode);

        state = readl(mbox->base + MBOX_MODE_REG(mchan->slot));
        return ((state & MBOX_STATE_MASK) == MBOX_STATE_IDLE);
}

static int hi6220_mbox_send_data(struct mbox_chan *chan, void *msg)
{
        struct hi6220_mbox_chan *mchan = chan->con_priv;
        struct hi6220_mbox *mbox = mchan->parent;
        unsigned int slot = mchan->slot;
        u32 *buf = msg;
        int i;

        /* indicate as a TX channel */
        mchan->dir = MBOX_TX;

        mbox_set_state(mbox, slot, MBOX_STATE_TX);

        if (mbox->tx_irq_mode)
                mbox_set_mode(mbox, slot, MBOX_ACK_IRQ);
        else
                mbox_set_mode(mbox, slot, MBOX_ACK_AUTOMATIC);

        for (i = 0; i < MBOX_MSG_LEN; i++)
                writel(buf[i], mbox->base + MBOX_DATA_REG(slot) + i * 4);

        /* trigger remote request */
        writel(BIT(mchan->dst_irq), DST_INT_RAW_REG(mbox->ipc));
        return 0;
}

static irqreturn_t hi6220_mbox_interrupt(int irq, void *p)
{
        struct hi6220_mbox *mbox = p;
        struct hi6220_mbox_chan *mchan;
        struct mbox_chan *chan;
        unsigned int state, intr_bit, i;
        u32 msg[MBOX_MSG_LEN];

        state = readl(ACK_INT_STAT_REG(mbox->ipc));
        if (!state) {
                dev_warn(mbox->dev, "%s: spurious interrupt\n",
                         __func__);
                return IRQ_HANDLED;
        }

        while (state) {
                intr_bit = __ffs(state);
                state &= (state - 1);

                chan = mbox->irq_map_chan[intr_bit];
                if (!chan) {
                        dev_warn(mbox->dev, "%s: unexpected irq vector %d\n",
                                 __func__, intr_bit);
                        continue;
                }

                mchan = chan->con_priv;
                if (mchan->dir == MBOX_TX)
                        mbox_chan_txdone(chan, 0);
                else {
                        for (i = 0; i < MBOX_MSG_LEN; i++)
                                msg[i] = readl(mbox->base +
                                        MBOX_DATA_REG(mchan->slot) + i * 4);

                        mbox_chan_received_data(chan, (void *)msg);
                }

                /* clear IRQ source */
                writel(BIT(mchan->ack_irq), ACK_INT_CLR_REG(mbox->ipc));
                mbox_set_state(mbox, mchan->slot, MBOX_STATE_IDLE);
        }

        return IRQ_HANDLED;
}

static int hi6220_mbox_startup(struct mbox_chan *chan)
{
        struct hi6220_mbox_chan *mchan = chan->con_priv;
        struct hi6220_mbox *mbox = mchan->parent;

        mchan->dir = 0;

        /* enable interrupt */
        writel(BIT(mchan->ack_irq), ACK_INT_ENA_REG(mbox->ipc));
        return 0;
}

static void hi6220_mbox_shutdown(struct mbox_chan *chan)
{
        struct hi6220_mbox_chan *mchan = chan->con_priv;
        struct hi6220_mbox *mbox = mchan->parent;

        /* disable interrupt */
        writel(BIT(mchan->ack_irq), ACK_INT_DIS_REG(mbox->ipc));
        mbox->irq_map_chan[mchan->ack_irq] = NULL;
}

static const struct mbox_chan_ops hi6220_mbox_ops = {
        .send_data    = hi6220_mbox_send_data,
        .startup      = hi6220_mbox_startup,
        .shutdown     = hi6220_mbox_shutdown,
        .last_tx_done = hi6220_mbox_last_tx_done,
};

static struct mbox_chan *hi6220_mbox_xlate(struct mbox_controller *controller,
                                           const struct of_phandle_args *spec)
{
        struct hi6220_mbox *mbox = dev_get_drvdata(controller->dev);
        struct hi6220_mbox_chan *mchan;
        struct mbox_chan *chan;
        unsigned int i = spec->args[0];
        unsigned int dst_irq = spec->args[1];
        unsigned int ack_irq = spec->args[2];

        /* Bounds checking */
        if (i >= mbox->chan_num || dst_irq >= mbox->chan_num ||
            ack_irq >= mbox->chan_num) {
                dev_err(mbox->dev,
                        "Invalid channel idx %d dst_irq %d ack_irq %d\n",
                        i, dst_irq, ack_irq);
                return ERR_PTR(-EINVAL);
        }

        /* Is requested channel free? */
        chan = &mbox->chan[i];
        if (mbox->irq_map_chan[ack_irq] == (void *)chan) {
                dev_err(mbox->dev, "Channel in use\n");
                return ERR_PTR(-EBUSY);
        }

        mchan = chan->con_priv;
        mchan->dst_irq = dst_irq;
        mchan->ack_irq = ack_irq;

        mbox->irq_map_chan[ack_irq] = (void *)chan;
        return chan;
}

static const struct of_device_id hi6220_mbox_of_match[] = {
        { .compatible = "hisilicon,hi6220-mbox", },
        {},
};
MODULE_DEVICE_TABLE(of, hi6220_mbox_of_match);

static int hi6220_mbox_probe(struct platform_device *pdev)
{
        struct device_node *node = pdev->dev.of_node;
        struct device *dev = &pdev->dev;
        struct hi6220_mbox *mbox;
        int i, err;

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

        mbox->dev = dev;
        mbox->chan_num = MBOX_CHAN_MAX;
        mbox->mchan = devm_kcalloc(dev,
                mbox->chan_num, sizeof(*mbox->mchan), GFP_KERNEL);
        if (!mbox->mchan)
                return -ENOMEM;

        mbox->chan = devm_kcalloc(dev,
                mbox->chan_num, sizeof(*mbox->chan), GFP_KERNEL);
        if (!mbox->chan)
                return -ENOMEM;

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

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

        mbox->base = devm_platform_ioremap_resource(pdev, 1);
        if (IS_ERR(mbox->base)) {
                dev_err(dev, "ioremap buffer failed\n");
                return PTR_ERR(mbox->base);
        }

        err = devm_request_irq(dev, mbox->irq, hi6220_mbox_interrupt, 0,
                        dev_name(dev), mbox);
        if (err) {
                dev_err(dev, "Failed to register a mailbox IRQ handler: %d\n",
                        err);
                return -ENODEV;
        }

        mbox->controller.dev = dev;
        mbox->controller.chans = &mbox->chan[0];
        mbox->controller.num_chans = mbox->chan_num;
        mbox->controller.ops = &hi6220_mbox_ops;
        mbox->controller.of_xlate = hi6220_mbox_xlate;

        for (i = 0; i < mbox->chan_num; i++) {
                mbox->chan[i].con_priv = &mbox->mchan[i];
                mbox->irq_map_chan[i] = NULL;

                mbox->mchan[i].parent = mbox;
                mbox->mchan[i].slot   = i;
        }

        /* mask and clear all interrupt vectors */
        writel(0x0,  ACK_INT_MSK_REG(mbox->ipc));
        writel(~0x0, ACK_INT_CLR_REG(mbox->ipc));

        /* use interrupt for tx's ack */
        mbox->tx_irq_mode = !of_property_read_bool(node, "hi6220,mbox-tx-noirq");

        if (mbox->tx_irq_mode)
                mbox->controller.txdone_irq = true;
        else {
                mbox->controller.txdone_poll = true;
                mbox->controller.txpoll_period = 5;
        }

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

        platform_set_drvdata(pdev, mbox);
        dev_info(dev, "Mailbox enabled\n");
        return 0;
}

static struct platform_driver hi6220_mbox_driver = {
        .driver = {
                .name = "hi6220-mbox",
                .of_match_table = hi6220_mbox_of_match,
        },
        .probe  = hi6220_mbox_probe,
};

static int __init hi6220_mbox_init(void)
{
        return platform_driver_register(&hi6220_mbox_driver);
}
core_initcall(hi6220_mbox_init);

static void __exit hi6220_mbox_exit(void)
{
        platform_driver_unregister(&hi6220_mbox_driver);
}
module_exit(hi6220_mbox_exit);

MODULE_AUTHOR("Leo Yan <leo.yan@linaro.org>");
MODULE_DESCRIPTION("Hi6220 mailbox driver");
MODULE_LICENSE("GPL v2");