// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * APM X-Gene SLIMpro MailBox Driver
 *
 * Copyright (c) 2015, Applied Micro Circuits Corporation
 * Author: Feng Kan fkan@apm.com
 */
#include <linux/acpi.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/mailbox_controller.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>

#define MBOX_CON_NAME                   "slimpro-mbox"
#define MBOX_REG_SET_OFFSET             0x1000
#define MBOX_CNT                        8
#define MBOX_STATUS_AVAIL_MASK          BIT(16)
#define MBOX_STATUS_ACK_MASK            BIT(0)

/* Configuration and Status Registers */
#define REG_DB_IN               0x00
#define REG_DB_DIN0             0x04
#define REG_DB_DIN1             0x08
#define REG_DB_OUT              0x10
#define REG_DB_DOUT0            0x14
#define REG_DB_DOUT1            0x18
#define REG_DB_STAT             0x20
#define REG_DB_STATMASK         0x24

/**
 * X-Gene SlimPRO mailbox channel information
 *
 * @dev:        Device to which it is attached
 * @chan:       Pointer to mailbox communication channel
 * @reg:        Base address to access channel registers
 * @irq:        Interrupt number of the channel
 * @rx_msg:     Received message storage
 */
struct slimpro_mbox_chan {
        struct device           *dev;
        struct mbox_chan        *chan;
        void __iomem            *reg;
        int                     irq;
        u32                     rx_msg[3];
};

/**
 * X-Gene SlimPRO Mailbox controller data
 *
 * X-Gene SlimPRO Mailbox controller has 8 communication channels.
 * Each channel has a separate IRQ number assigned to it.
 *
 * @mb_ctrl:    Representation of the communication channel controller
 * @mc:         Array of SlimPRO mailbox channels of the controller
 * @chans:      Array of mailbox communication channels
 *
 */
struct slimpro_mbox {
        struct mbox_controller          mb_ctrl;
        struct slimpro_mbox_chan        mc[MBOX_CNT];
        struct mbox_chan                chans[MBOX_CNT];
};

static void mb_chan_send_msg(struct slimpro_mbox_chan *mb_chan, u32 *msg)
{
        writel(msg[1], mb_chan->reg + REG_DB_DOUT0);
        writel(msg[2], mb_chan->reg + REG_DB_DOUT1);
        writel(msg[0], mb_chan->reg + REG_DB_OUT);
}

static void mb_chan_recv_msg(struct slimpro_mbox_chan *mb_chan)
{
        mb_chan->rx_msg[1] = readl(mb_chan->reg + REG_DB_DIN0);
        mb_chan->rx_msg[2] = readl(mb_chan->reg + REG_DB_DIN1);
        mb_chan->rx_msg[0] = readl(mb_chan->reg + REG_DB_IN);
}

static int mb_chan_status_ack(struct slimpro_mbox_chan *mb_chan)
{
        u32 val = readl(mb_chan->reg + REG_DB_STAT);

        if (val & MBOX_STATUS_ACK_MASK) {
                writel(MBOX_STATUS_ACK_MASK, mb_chan->reg + REG_DB_STAT);
                return 1;
        }
        return 0;
}

static int mb_chan_status_avail(struct slimpro_mbox_chan *mb_chan)
{
        u32 val = readl(mb_chan->reg + REG_DB_STAT);

        if (val & MBOX_STATUS_AVAIL_MASK) {
                mb_chan_recv_msg(mb_chan);
                writel(MBOX_STATUS_AVAIL_MASK, mb_chan->reg + REG_DB_STAT);
                return 1;
        }
        return 0;
}

static irqreturn_t slimpro_mbox_irq(int irq, void *id)
{
        struct slimpro_mbox_chan *mb_chan = id;

        if (mb_chan_status_ack(mb_chan))
                mbox_chan_txdone(mb_chan->chan, 0);

        if (mb_chan_status_avail(mb_chan))
                mbox_chan_received_data(mb_chan->chan, mb_chan->rx_msg);

        return IRQ_HANDLED;
}

static int slimpro_mbox_send_data(struct mbox_chan *chan, void *msg)
{
        struct slimpro_mbox_chan *mb_chan = chan->con_priv;

        mb_chan_send_msg(mb_chan, msg);
        return 0;
}

static int slimpro_mbox_startup(struct mbox_chan *chan)
{
        struct slimpro_mbox_chan *mb_chan = chan->con_priv;
        int rc;
        u32 val;

        rc = devm_request_irq(mb_chan->dev, mb_chan->irq, slimpro_mbox_irq, 0,
                              MBOX_CON_NAME, mb_chan);
        if (unlikely(rc)) {
                dev_err(mb_chan->dev, "failed to register mailbox interrupt %d\n",
                        mb_chan->irq);
                return rc;
        }

        /* Enable HW interrupt */
        writel(MBOX_STATUS_ACK_MASK | MBOX_STATUS_AVAIL_MASK,
               mb_chan->reg + REG_DB_STAT);
        /* Unmask doorbell status interrupt */
        val = readl(mb_chan->reg + REG_DB_STATMASK);
        val &= ~(MBOX_STATUS_ACK_MASK | MBOX_STATUS_AVAIL_MASK);
        writel(val, mb_chan->reg + REG_DB_STATMASK);

        return 0;
}

static void slimpro_mbox_shutdown(struct mbox_chan *chan)
{
        struct slimpro_mbox_chan *mb_chan = chan->con_priv;
        u32 val;

        /* Mask doorbell status interrupt */
        val = readl(mb_chan->reg + REG_DB_STATMASK);
        val |= (MBOX_STATUS_ACK_MASK | MBOX_STATUS_AVAIL_MASK);
        writel(val, mb_chan->reg + REG_DB_STATMASK);

        devm_free_irq(mb_chan->dev, mb_chan->irq, mb_chan);
}

static const struct mbox_chan_ops slimpro_mbox_ops = {
        .send_data = slimpro_mbox_send_data,
        .startup = slimpro_mbox_startup,
        .shutdown = slimpro_mbox_shutdown,
};

static int slimpro_mbox_probe(struct platform_device *pdev)
{
        struct slimpro_mbox *ctx;
        void __iomem *mb_base;
        int rc;
        int i;

        ctx = devm_kzalloc(&pdev->dev, sizeof(struct slimpro_mbox), GFP_KERNEL);
        if (!ctx)
                return -ENOMEM;

        platform_set_drvdata(pdev, ctx);

        mb_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(mb_base))
                return PTR_ERR(mb_base);

        /* Setup mailbox links */
        for (i = 0; i < MBOX_CNT; i++) {
                ctx->mc[i].irq = platform_get_irq(pdev, i);
                if (ctx->mc[i].irq < 0) {
                        if (i == 0) {
                                dev_err(&pdev->dev, "no available IRQ\n");
                                return -EINVAL;
                        }
                        dev_info(&pdev->dev, "no IRQ for channel %d\n", i);
                        break;
                }

                ctx->mc[i].dev = &pdev->dev;
                ctx->mc[i].reg = mb_base + i * MBOX_REG_SET_OFFSET;
                ctx->mc[i].chan = &ctx->chans[i];
                ctx->chans[i].con_priv = &ctx->mc[i];
        }

        /* Setup mailbox controller */
        ctx->mb_ctrl.dev = &pdev->dev;
        ctx->mb_ctrl.chans = ctx->chans;
        ctx->mb_ctrl.txdone_irq = true;
        ctx->mb_ctrl.ops = &slimpro_mbox_ops;
        ctx->mb_ctrl.num_chans = i;

        rc = devm_mbox_controller_register(&pdev->dev, &ctx->mb_ctrl);
        if (rc) {
                dev_err(&pdev->dev,
                        "APM X-Gene SLIMpro MailBox register failed:%d\n", rc);
                return rc;
        }

        dev_info(&pdev->dev, "APM X-Gene SLIMpro MailBox registered\n");
        return 0;
}

static const struct of_device_id slimpro_of_match[] = {
        {.compatible = "apm,xgene-slimpro-mbox" },
        { },
};
MODULE_DEVICE_TABLE(of, slimpro_of_match);

#ifdef CONFIG_ACPI
static const struct acpi_device_id slimpro_acpi_ids[] = {
        {"APMC0D01", 0},
        {}
};
MODULE_DEVICE_TABLE(acpi, slimpro_acpi_ids);
#endif

static struct platform_driver slimpro_mbox_driver = {
        .probe  = slimpro_mbox_probe,
        .driver = {
                .name = "xgene-slimpro-mbox",
                .of_match_table = of_match_ptr(slimpro_of_match),
                .acpi_match_table = ACPI_PTR(slimpro_acpi_ids)
        },
};

static int __init slimpro_mbox_init(void)
{
        return platform_driver_register(&slimpro_mbox_driver);
}

static void __exit slimpro_mbox_exit(void)
{
        platform_driver_unregister(&slimpro_mbox_driver);
}

subsys_initcall(slimpro_mbox_init);
module_exit(slimpro_mbox_exit);

MODULE_DESCRIPTION("APM X-Gene SLIMpro Mailbox Driver");
MODULE_LICENSE("GPL");