// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * STi Mailbox
 *
 * Copyright (C) 2015 ST Microelectronics
 *
 * Author: Lee Jones <lee.jones@linaro.org> for ST Microelectronics
 *
 * Based on the original driver written by;
 *   Alexandre Torgue, Olivier Lebreton and Loic Pallardy
 */

#include <linux/err.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>
#include <linux/property.h>
#include <linux/slab.h>

#include "mailbox.h"

#define STI_MBOX_INST_MAX       4      /* RAM saving: Max supported instances */
#define STI_MBOX_CHAN_MAX       20     /* RAM saving: Max supported channels  */

#define STI_IRQ_VAL_OFFSET      0x04   /* Read interrupt status               */
#define STI_IRQ_SET_OFFSET      0x24   /* Generate a Tx channel interrupt     */
#define STI_IRQ_CLR_OFFSET      0x44   /* Clear pending Rx interrupts         */
#define STI_ENA_VAL_OFFSET      0x64   /* Read enable status                  */
#define STI_ENA_SET_OFFSET      0x84   /* Enable a channel                    */
#define STI_ENA_CLR_OFFSET      0xa4   /* Disable a channel                   */

#define MBOX_BASE(mdev, inst)   ((mdev)->base + ((inst) * 4))

/**
 * struct sti_mbox_device - STi Mailbox device data
 *
 * @dev:        Device to which it is attached
 * @mbox:       Representation of a communication channel controller
 * @base:       Base address of the register mapping region
 * @name:       Name of the mailbox
 * @enabled:    Local copy of enabled channels
 * @lock:       Mutex protecting enabled status
 *
 * An IP Mailbox is currently composed of 4 instances
 * Each instance is currently composed of 32 channels
 * This means that we have 128 channels per Mailbox
 * A channel an be used for TX or RX
 */
struct sti_mbox_device {
        struct device           *dev;
        struct mbox_controller  *mbox;
        void __iomem            *base;
        const char              *name;
        u32                     enabled[STI_MBOX_INST_MAX];
        spinlock_t              lock;
};

/**
 * struct sti_mbox_pdata - STi Mailbox platform specific configuration
 *
 * @num_inst:   Maximum number of instances in one HW Mailbox
 * @num_chan:   Maximum number of channel per instance
 */
struct sti_mbox_pdata {
        unsigned int            num_inst;
        unsigned int            num_chan;
};

/**
 * struct sti_channel - STi Mailbox allocated channel information
 *
 * @mdev:       Pointer to parent Mailbox device
 * @instance:   Instance number channel resides in
 * @channel:    Channel number pertaining to this container
 */
struct sti_channel {
        struct sti_mbox_device  *mdev;
        unsigned int            instance;
        unsigned int            channel;
};

static inline bool sti_mbox_channel_is_enabled(struct mbox_chan *chan)
{
        struct sti_channel *chan_info = chan->con_priv;
        struct sti_mbox_device *mdev = chan_info->mdev;
        unsigned int instance = chan_info->instance;
        unsigned int channel = chan_info->channel;

        return mdev->enabled[instance] & BIT(channel);
}

static inline
struct mbox_chan *sti_mbox_to_channel(struct mbox_controller *mbox,
                                      unsigned int instance,
                                      unsigned int channel)
{
        struct sti_channel *chan_info;
        int i;

        for (i = 0; i < mbox->num_chans; i++) {
                chan_info = mbox->chans[i].con_priv;
                if (chan_info &&
                    chan_info->instance == instance &&
                    chan_info->channel == channel)
                        return &mbox->chans[i];
        }

        dev_err(mbox->dev,
                "Channel not registered: instance: %d channel: %d\n",
                instance, channel);

        return NULL;
}

static void sti_mbox_enable_channel(struct mbox_chan *chan)
{
        struct sti_channel *chan_info = chan->con_priv;
        struct sti_mbox_device *mdev = chan_info->mdev;
        unsigned int instance = chan_info->instance;
        unsigned int channel = chan_info->channel;
        unsigned long flags;
        void __iomem *base = MBOX_BASE(mdev, instance);

        spin_lock_irqsave(&mdev->lock, flags);
        mdev->enabled[instance] |= BIT(channel);
        writel_relaxed(BIT(channel), base + STI_ENA_SET_OFFSET);
        spin_unlock_irqrestore(&mdev->lock, flags);
}

static void sti_mbox_disable_channel(struct mbox_chan *chan)
{
        struct sti_channel *chan_info = chan->con_priv;
        struct sti_mbox_device *mdev = chan_info->mdev;
        unsigned int instance = chan_info->instance;
        unsigned int channel = chan_info->channel;
        unsigned long flags;
        void __iomem *base = MBOX_BASE(mdev, instance);

        spin_lock_irqsave(&mdev->lock, flags);
        mdev->enabled[instance] &= ~BIT(channel);
        writel_relaxed(BIT(channel), base + STI_ENA_CLR_OFFSET);
        spin_unlock_irqrestore(&mdev->lock, flags);
}

static void sti_mbox_clear_irq(struct mbox_chan *chan)
{
        struct sti_channel *chan_info = chan->con_priv;
        struct sti_mbox_device *mdev = chan_info->mdev;
        unsigned int instance = chan_info->instance;
        unsigned int channel = chan_info->channel;
        void __iomem *base = MBOX_BASE(mdev, instance);

        writel_relaxed(BIT(channel), base + STI_IRQ_CLR_OFFSET);
}

static struct mbox_chan *sti_mbox_irq_to_channel(struct sti_mbox_device *mdev,
                                                 unsigned int instance)
{
        struct mbox_controller *mbox = mdev->mbox;
        struct mbox_chan *chan = NULL;
        unsigned int channel;
        unsigned long bits;
        void __iomem *base = MBOX_BASE(mdev, instance);

        bits = readl_relaxed(base + STI_IRQ_VAL_OFFSET);
        if (!bits)
                /* No IRQs fired in specified instance */
                return NULL;

        /* An IRQ has fired, find the associated channel */
        for (channel = 0; bits; channel++) {
                if (!test_and_clear_bit(channel, &bits))
                        continue;

                chan = sti_mbox_to_channel(mbox, instance, channel);
                if (chan) {
                        dev_dbg(mbox->dev,
                                "IRQ fired on instance: %d channel: %d\n",
                                instance, channel);
                        break;
                }
        }

        return chan;
}

static irqreturn_t sti_mbox_thread_handler(int irq, void *data)
{
        struct sti_mbox_device *mdev = data;
        struct sti_mbox_pdata *pdata = dev_get_platdata(mdev->dev);
        struct mbox_chan *chan;
        unsigned int instance;

        for (instance = 0; instance < pdata->num_inst; instance++) {
keep_looking:
                chan = sti_mbox_irq_to_channel(mdev, instance);
                if (!chan)
                        continue;

                mbox_chan_received_data(chan, NULL);
                sti_mbox_clear_irq(chan);
                sti_mbox_enable_channel(chan);
                goto keep_looking;
        }

        return IRQ_HANDLED;
}

static irqreturn_t sti_mbox_irq_handler(int irq, void *data)
{
        struct sti_mbox_device *mdev = data;
        struct sti_mbox_pdata *pdata = dev_get_platdata(mdev->dev);
        struct sti_channel *chan_info;
        struct mbox_chan *chan;
        unsigned int instance;
        int ret = IRQ_NONE;

        for (instance = 0; instance < pdata->num_inst; instance++) {
                chan = sti_mbox_irq_to_channel(mdev, instance);
                if (!chan)
                        continue;
                chan_info = chan->con_priv;

                if (!sti_mbox_channel_is_enabled(chan)) {
                        dev_warn(mdev->dev,
                                 "Unexpected IRQ: %s\n"
                                 "  instance: %d: channel: %d [enabled: %x]\n",
                                 mdev->name, chan_info->instance,
                                 chan_info->channel, mdev->enabled[instance]);

                        /* Only handle IRQ if no other valid IRQs were found */
                        if (ret == IRQ_NONE)
                                ret = IRQ_HANDLED;
                        continue;
                }

                sti_mbox_disable_channel(chan);
                ret = IRQ_WAKE_THREAD;
        }

        if (ret == IRQ_NONE)
                dev_err(mdev->dev, "Spurious IRQ - was a channel requested?\n");

        return ret;
}

static bool sti_mbox_tx_is_ready(struct mbox_chan *chan)
{
        struct sti_channel *chan_info = chan->con_priv;
        struct sti_mbox_device *mdev = chan_info->mdev;
        unsigned int instance = chan_info->instance;
        unsigned int channel = chan_info->channel;
        void __iomem *base = MBOX_BASE(mdev, instance);

        if (!(readl_relaxed(base + STI_ENA_VAL_OFFSET) & BIT(channel))) {
                dev_dbg(mdev->dev, "Mbox: %s: inst: %d, chan: %d disabled\n",
                        mdev->name, instance, channel);
                return false;
        }

        if (readl_relaxed(base + STI_IRQ_VAL_OFFSET) & BIT(channel)) {
                dev_dbg(mdev->dev, "Mbox: %s: inst: %d, chan: %d not ready\n",
                        mdev->name, instance, channel);
                return false;
        }

        return true;
}

static int sti_mbox_send_data(struct mbox_chan *chan, void *data)
{
        struct sti_channel *chan_info = chan->con_priv;
        struct sti_mbox_device *mdev = chan_info->mdev;
        unsigned int instance = chan_info->instance;
        unsigned int channel = chan_info->channel;
        void __iomem *base = MBOX_BASE(mdev, instance);

        /* Send event to co-processor */
        writel_relaxed(BIT(channel), base + STI_IRQ_SET_OFFSET);

        dev_dbg(mdev->dev,
                "Sent via Mailbox %s: instance: %d channel: %d\n",
                mdev->name, instance, channel);

        return 0;
}

static int sti_mbox_startup_chan(struct mbox_chan *chan)
{
        sti_mbox_clear_irq(chan);
        sti_mbox_enable_channel(chan);

        return 0;
}

static void sti_mbox_shutdown_chan(struct mbox_chan *chan)
{
        struct sti_channel *chan_info = chan->con_priv;
        struct mbox_controller *mbox = chan_info->mdev->mbox;
        int i;

        for (i = 0; i < mbox->num_chans; i++)
                if (chan == &mbox->chans[i])
                        break;

        if (mbox->num_chans == i) {
                dev_warn(mbox->dev, "Request to free non-existent channel\n");
                return;
        }

        /* Reset channel */
        sti_mbox_disable_channel(chan);
        sti_mbox_clear_irq(chan);
        chan->con_priv = NULL;
}

static struct mbox_chan *sti_mbox_xlate(struct mbox_controller *mbox,
                                        const struct of_phandle_args *spec)
{
        struct sti_mbox_device *mdev = dev_get_drvdata(mbox->dev);
        struct sti_mbox_pdata *pdata = dev_get_platdata(mdev->dev);
        struct sti_channel *chan_info;
        struct mbox_chan *chan = NULL;
        unsigned int instance  = spec->args[0];
        unsigned int channel   = spec->args[1];
        int i;

        /* Bounds checking */
        if (instance >= pdata->num_inst || channel  >= pdata->num_chan) {
                dev_err(mbox->dev,
                        "Invalid channel requested instance: %d channel: %d\n",
                        instance, channel);
                return ERR_PTR(-EINVAL);
        }

        for (i = 0; i < mbox->num_chans; i++) {
                chan_info = mbox->chans[i].con_priv;

                /* Is requested channel free? */
                if (chan_info &&
                    mbox->dev == chan_info->mdev->dev &&
                    instance == chan_info->instance &&
                    channel == chan_info->channel) {

                        dev_err(mbox->dev, "Channel in use\n");
                        return ERR_PTR(-EBUSY);
                }

                /*
                 * Find the first free slot, then continue checking
                 * to see if requested channel is in use
                 */
                if (!chan && !chan_info)
                        chan = &mbox->chans[i];
        }

        if (!chan) {
                dev_err(mbox->dev, "No free channels left\n");
                return ERR_PTR(-EBUSY);
        }

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

        chan_info->mdev         = mdev;
        chan_info->instance     = instance;
        chan_info->channel      = channel;

        chan->con_priv = chan_info;

        dev_info(mbox->dev,
                 "Mbox: %s: Created channel: instance: %d channel: %d\n",
                 mdev->name, instance, channel);

        return chan;
}

static const struct mbox_chan_ops sti_mbox_ops = {
        .startup        = sti_mbox_startup_chan,
        .shutdown       = sti_mbox_shutdown_chan,
        .send_data      = sti_mbox_send_data,
        .last_tx_done   = sti_mbox_tx_is_ready,
};

static const struct sti_mbox_pdata mbox_stih407_pdata = {
        .num_inst       = 4,
        .num_chan       = 32,
};

static const struct of_device_id sti_mailbox_match[] = {
        {
                .compatible = "st,stih407-mailbox",
                .data = (void *)&mbox_stih407_pdata
        },
        { }
};
MODULE_DEVICE_TABLE(of, sti_mailbox_match);

static int sti_mbox_probe(struct platform_device *pdev)
{
        struct mbox_controller *mbox;
        struct sti_mbox_device *mdev;
        struct device_node *np = pdev->dev.of_node;
        struct mbox_chan *chans;
        int irq;
        int ret;

        pdev->dev.platform_data = (struct sti_mbox_pdata *)device_get_match_data(&pdev->dev);
        if (!pdev->dev.platform_data) {
                dev_err(&pdev->dev, "No configuration found\n");
                return -ENODEV;
        }

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

        platform_set_drvdata(pdev, mdev);

        mdev->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(mdev->base))
                return PTR_ERR(mdev->base);

        ret = of_property_read_string(np, "mbox-name", &mdev->name);
        if (ret)
                mdev->name = np->full_name;

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

        chans = devm_kcalloc(&pdev->dev,
                             STI_MBOX_CHAN_MAX, sizeof(*chans), GFP_KERNEL);
        if (!chans)
                return -ENOMEM;

        mdev->dev               = &pdev->dev;
        mdev->mbox              = mbox;

        spin_lock_init(&mdev->lock);

        /* STi Mailbox does not have a Tx-Done or Tx-Ready IRQ */
        mbox->txdone_irq        = false;
        mbox->txdone_poll       = true;
        mbox->txpoll_period     = 100;
        mbox->ops               = &sti_mbox_ops;
        mbox->dev               = mdev->dev;
        mbox->of_xlate          = sti_mbox_xlate;
        mbox->chans             = chans;
        mbox->num_chans         = STI_MBOX_CHAN_MAX;

        ret = devm_mbox_controller_register(&pdev->dev, mbox);
        if (ret)
                return ret;

        /* It's okay for Tx Mailboxes to not supply IRQs */
        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_info(&pdev->dev,
                         "%s: Registered Tx only Mailbox\n", mdev->name);
                return 0;
        }

        ret = devm_request_threaded_irq(&pdev->dev, irq,
                                        sti_mbox_irq_handler,
                                        sti_mbox_thread_handler,
                                        IRQF_ONESHOT, mdev->name, mdev);
        if (ret) {
                dev_err(&pdev->dev, "Can't claim IRQ %d\n", irq);
                return -EINVAL;
        }

        dev_info(&pdev->dev, "%s: Registered Tx/Rx Mailbox\n", mdev->name);

        return 0;
}

static struct platform_driver sti_mbox_driver = {
        .probe = sti_mbox_probe,
        .driver = {
                .name = "sti-mailbox",
                .of_match_table = sti_mailbox_match,
        },
};
module_platform_driver(sti_mbox_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("STMicroelectronics Mailbox Controller");
MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org");
MODULE_ALIAS("platform:mailbox-sti");