/*
 * Texas Instruments' Message Manager Driver
 *
 * Copyright (C) 2015-2016 Texas Instruments Incorporated - http://www.ti.com/
 *      Nishanth Menon
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#define pr_fmt(fmt) "%s: " fmt, __func__

#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_device.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/soc/ti/ti-msgmgr.h>

#define Q_DATA_OFFSET(proxy, queue, reg)        \
                     ((0x10000 * (proxy)) + (0x80 * (queue)) + ((reg) * 4))
#define Q_STATE_OFFSET(queue)                   ((queue) * 0x4)
#define Q_STATE_ENTRY_COUNT_MASK                (0xFFF000)

/**
 * struct ti_msgmgr_valid_queue_desc - SoC valid queues meant for this processor
 * @queue_id:   Queue Number for this path
 * @proxy_id:   Proxy ID representing the processor in SoC
 * @is_tx:      Is this a receive path?
 */
struct ti_msgmgr_valid_queue_desc {
        u8 queue_id;
        u8 proxy_id;
        bool is_tx;
};

/**
 * struct ti_msgmgr_desc - Description of message manager integration
 * @queue_count:        Number of Queues
 * @max_message_size:   Message size in bytes
 * @max_messages:       Number of messages
 * @q_slices:           Number of queue engines
 * @q_proxies:          Number of queue proxies per page
 * @data_first_reg:     First data register for proxy data region
 * @data_last_reg:      Last data register for proxy data region
 * @tx_polled:          Do I need to use polled mechanism for tx
 * @tx_poll_timeout_ms: Timeout in ms if polled
 * @valid_queues:       List of Valid queues that the processor can access
 * @num_valid_queues:   Number of valid queues
 *
 * This structure is used in of match data to describe how integration
 * for a specific compatible SoC is done.
 */
struct ti_msgmgr_desc {
        u8 queue_count;
        u8 max_message_size;
        u8 max_messages;
        u8 q_slices;
        u8 q_proxies;
        u8 data_first_reg;
        u8 data_last_reg;
        bool tx_polled;
        int tx_poll_timeout_ms;
        const struct ti_msgmgr_valid_queue_desc *valid_queues;
        int num_valid_queues;
};

/**
 * struct ti_queue_inst - Description of a queue instance
 * @name:       Queue Name
 * @queue_id:   Queue Identifier as mapped on SoC
 * @proxy_id:   Proxy Identifier as mapped on SoC
 * @irq:        IRQ for Rx Queue
 * @is_tx:      'true' if transmit queue, else, 'false'
 * @queue_buff_start: First register of Data Buffer
 * @queue_buff_end: Last (or confirmation) register of Data buffer
 * @queue_state: Queue status register
 * @chan:       Mailbox channel
 * @rx_buff:    Receive buffer pointer allocated at probe, max_message_size
 */
struct ti_queue_inst {
        char name[30];
        u8 queue_id;
        u8 proxy_id;
        int irq;
        bool is_tx;
        void __iomem *queue_buff_start;
        void __iomem *queue_buff_end;
        void __iomem *queue_state;
        struct mbox_chan *chan;
        u32 *rx_buff;
};

/**
 * struct ti_msgmgr_inst - Description of a Message Manager Instance
 * @dev:        device pointer corresponding to the Message Manager instance
 * @desc:       Description of the SoC integration
 * @queue_proxy_region: Queue proxy region where queue buffers are located
 * @queue_state_debug_region:   Queue status register regions
 * @num_valid_queues:   Number of valid queues defined for the processor
 *              Note: other queues are probably reserved for other processors
 *              in the SoC.
 * @qinsts:     Array of valid Queue Instances for the Processor
 * @mbox:       Mailbox Controller
 * @chans:      Array for channels corresponding to the Queue Instances.
 */
struct ti_msgmgr_inst {
        struct device *dev;
        const struct ti_msgmgr_desc *desc;
        void __iomem *queue_proxy_region;
        void __iomem *queue_state_debug_region;
        u8 num_valid_queues;
        struct ti_queue_inst *qinsts;
        struct mbox_controller mbox;
        struct mbox_chan *chans;
};

/**
 * ti_msgmgr_queue_get_num_messages() - Get the number of pending messages
 * @qinst:      Queue instance for which we check the number of pending messages
 *
 * Return: number of messages pending in the queue (0 == no pending messages)
 */
static inline int ti_msgmgr_queue_get_num_messages(struct ti_queue_inst *qinst)
{
        u32 val;

        /*
         * We cannot use relaxed operation here - update may happen
         * real-time.
         */
        val = readl(qinst->queue_state) & Q_STATE_ENTRY_COUNT_MASK;
        val >>= __ffs(Q_STATE_ENTRY_COUNT_MASK);

        return val;
}

/**
 * ti_msgmgr_queue_rx_interrupt() - Interrupt handler for receive Queue
 * @irq:        Interrupt number
 * @p:          Channel Pointer
 *
 * Return: -EINVAL if there is no instance
 * IRQ_NONE if the interrupt is not ours.
 * IRQ_HANDLED if the rx interrupt was successfully handled.
 */
static irqreturn_t ti_msgmgr_queue_rx_interrupt(int irq, void *p)
{
        struct mbox_chan *chan = p;
        struct device *dev = chan->mbox->dev;
        struct ti_msgmgr_inst *inst = dev_get_drvdata(dev);
        struct ti_queue_inst *qinst = chan->con_priv;
        const struct ti_msgmgr_desc *desc;
        int msg_count, num_words;
        struct ti_msgmgr_message message;
        void __iomem *data_reg;
        u32 *word_data;

        if (WARN_ON(!inst)) {
                dev_err(dev, "no platform drv data??\n");
                return -EINVAL;
        }

        /* Do I have an invalid interrupt source? */
        if (qinst->is_tx) {
                dev_err(dev, "Cannot handle rx interrupt on tx channel %s\n",
                        qinst->name);
                return IRQ_NONE;
        }

        /* Do I actually have messages to read? */
        msg_count = ti_msgmgr_queue_get_num_messages(qinst);
        if (!msg_count) {
                /* Shared IRQ? */
                dev_dbg(dev, "Spurious event - 0 pending data!\n");
                return IRQ_NONE;
        }

        /*
         * I have no idea about the protocol being used to communicate with the
         * remote producer - 0 could be valid data, so I wont make a judgement
         * of how many bytes I should be reading. Let the client figure this
         * out.. I just read the full message and pass it on..
         */
        desc = inst->desc;
        message.len = desc->max_message_size;
        message.buf = (u8 *)qinst->rx_buff;

        /*
         * NOTE about register access involved here:
         * the hardware block is implemented with 32bit access operations and no
         * support for data splitting.  We don't want the hardware to misbehave
         * with sub 32bit access - For example: if the last register read is
         * split into byte wise access, it can result in the queue getting
         * stuck or indeterminate behavior. An out of order read operation may
         * result in weird data results as well.
         * Hence, we do not use memcpy_fromio or __ioread32_copy here, instead
         * we depend on readl for the purpose.
         *
         * Also note that the final register read automatically marks the
         * queue message as read.
         */
        for (data_reg = qinst->queue_buff_start, word_data = qinst->rx_buff,
             num_words = (desc->max_message_size / sizeof(u32));
             num_words; num_words--, data_reg += sizeof(u32), word_data++)
                *word_data = readl(data_reg);

        /*
         * Last register read automatically clears the IRQ if only 1 message
         * is pending - so send the data up the stack..
         * NOTE: Client is expected to be as optimal as possible, since
         * we invoke the handler in IRQ context.
         */
        mbox_chan_received_data(chan, (void *)&message);

        return IRQ_HANDLED;
}

/**
 * ti_msgmgr_queue_peek_data() - Peek to see if there are any rx messages.
 * @chan:       Channel Pointer
 *
 * Return: 'true' if there is pending rx data, 'false' if there is none.
 */
static bool ti_msgmgr_queue_peek_data(struct mbox_chan *chan)
{
        struct ti_queue_inst *qinst = chan->con_priv;
        int msg_count;

        if (qinst->is_tx)
                return false;

        msg_count = ti_msgmgr_queue_get_num_messages(qinst);

        return msg_count ? true : false;
}

/**
 * ti_msgmgr_last_tx_done() - See if all the tx messages are sent
 * @chan:       Channel pointer
 *
 * Return: 'true' is no pending tx data, 'false' if there are any.
 */
static bool ti_msgmgr_last_tx_done(struct mbox_chan *chan)
{
        struct ti_queue_inst *qinst = chan->con_priv;
        int msg_count;

        if (!qinst->is_tx)
                return false;

        msg_count = ti_msgmgr_queue_get_num_messages(qinst);

        /* if we have any messages pending.. */
        return msg_count ? false : true;
}

/**
 * ti_msgmgr_send_data() - Send data
 * @chan:       Channel Pointer
 * @data:       ti_msgmgr_message * Message Pointer
 *
 * Return: 0 if all goes good, else appropriate error messages.
 */
static int ti_msgmgr_send_data(struct mbox_chan *chan, void *data)
{
        struct device *dev = chan->mbox->dev;
        struct ti_msgmgr_inst *inst = dev_get_drvdata(dev);
        const struct ti_msgmgr_desc *desc;
        struct ti_queue_inst *qinst = chan->con_priv;
        int num_words, trail_bytes;
        struct ti_msgmgr_message *message = data;
        void __iomem *data_reg;
        u32 *word_data;

        if (WARN_ON(!inst)) {
                dev_err(dev, "no platform drv data??\n");
                return -EINVAL;
        }
        desc = inst->desc;

        if (desc->max_message_size < message->len) {
                dev_err(dev, "Queue %s message length %d > max %d\n",
                        qinst->name, message->len, desc->max_message_size);
                return -EINVAL;
        }

        /* NOTE: Constraints similar to rx path exists here as well */
        for (data_reg = qinst->queue_buff_start,
             num_words = message->len / sizeof(u32),
             word_data = (u32 *)message->buf;
             num_words; num_words--, data_reg += sizeof(u32), word_data++)
                writel(*word_data, data_reg);

        trail_bytes = message->len % sizeof(u32);
        if (trail_bytes) {
                u32 data_trail = *word_data;

                /* Ensure all unused data is 0 */
                data_trail &= 0xFFFFFFFF >> (8 * (sizeof(u32) - trail_bytes));
                writel(data_trail, data_reg);
                data_reg++;
        }
        /*
         * 'data_reg' indicates next register to write. If we did not already
         * write on tx complete reg(last reg), we must do so for transmit
         */
        if (data_reg <= qinst->queue_buff_end)
                writel(0, qinst->queue_buff_end);

        return 0;
}

/**
 * ti_msgmgr_queue_startup() - Startup queue
 * @chan:       Channel pointer
 *
 * Return: 0 if all goes good, else return corresponding error message
 */
static int ti_msgmgr_queue_startup(struct mbox_chan *chan)
{
        struct ti_queue_inst *qinst = chan->con_priv;
        struct device *dev = chan->mbox->dev;
        int ret;

        if (!qinst->is_tx) {
                /*
                 * With the expectation that the IRQ might be shared in SoC
                 */
                ret = request_irq(qinst->irq, ti_msgmgr_queue_rx_interrupt,
                                  IRQF_SHARED, qinst->name, chan);
                if (ret) {
                        dev_err(dev, "Unable to get IRQ %d on %s(res=%d)\n",
                                qinst->irq, qinst->name, ret);
                        return ret;
                }
        }

        return 0;
}

/**
 * ti_msgmgr_queue_shutdown() - Shutdown the queue
 * @chan:       Channel pointer
 */
static void ti_msgmgr_queue_shutdown(struct mbox_chan *chan)
{
        struct ti_queue_inst *qinst = chan->con_priv;

        if (!qinst->is_tx)
                free_irq(qinst->irq, chan);
}

/**
 * ti_msgmgr_of_xlate() - Translation of phandle to queue
 * @mbox:       Mailbox controller
 * @p:          phandle pointer
 *
 * Return: Mailbox channel corresponding to the queue, else return error
 * pointer.
 */
static struct mbox_chan *ti_msgmgr_of_xlate(struct mbox_controller *mbox,
                                            const struct of_phandle_args *p)
{
        struct ti_msgmgr_inst *inst;
        int req_qid, req_pid;
        struct ti_queue_inst *qinst;
        int i;

        inst = container_of(mbox, struct ti_msgmgr_inst, mbox);
        if (WARN_ON(!inst))
                return ERR_PTR(-EINVAL);

        /* #mbox-cells is 2 */
        if (p->args_count != 2) {
                dev_err(inst->dev, "Invalid arguments in dt[%d] instead of 2\n",
                        p->args_count);
                return ERR_PTR(-EINVAL);
        }
        req_qid = p->args[0];
        req_pid = p->args[1];

        for (qinst = inst->qinsts, i = 0; i < inst->num_valid_queues;
             i++, qinst++) {
                if (req_qid == qinst->queue_id && req_pid == qinst->proxy_id)
                        return qinst->chan;
        }

        dev_err(inst->dev, "Queue ID %d, Proxy ID %d is wrong on %s\n",
                req_qid, req_pid, p->np->name);
        return ERR_PTR(-ENOENT);
}

/**
 * ti_msgmgr_queue_setup() - Setup data structures for each queue instance
 * @idx:        index of the queue
 * @dev:        pointer to the message manager device
 * @np:         pointer to the of node
 * @inst:       Queue instance pointer
 * @d:          Message Manager instance description data
 * @qd:         Queue description data
 * @qinst:      Queue instance pointer
 * @chan:       pointer to mailbox channel
 *
 * Return: 0 if all went well, else return corresponding error
 */
static int ti_msgmgr_queue_setup(int idx, struct device *dev,
                                 struct device_node *np,
                                 struct ti_msgmgr_inst *inst,
                                 const struct ti_msgmgr_desc *d,
                                 const struct ti_msgmgr_valid_queue_desc *qd,
                                 struct ti_queue_inst *qinst,
                                 struct mbox_chan *chan)
{
        qinst->proxy_id = qd->proxy_id;
        qinst->queue_id = qd->queue_id;

        if (qinst->queue_id > d->queue_count) {
                dev_err(dev, "Queue Data [idx=%d] queuid %d > %d\n",
                        idx, qinst->queue_id, d->queue_count);
                return -ERANGE;
        }

        qinst->is_tx = qd->is_tx;
        snprintf(qinst->name, sizeof(qinst->name), "%s %s_%03d_%03d",
                 dev_name(dev), qinst->is_tx ? "tx" : "rx", qinst->queue_id,
                 qinst->proxy_id);

        if (!qinst->is_tx) {
                char of_rx_irq_name[7];

                snprintf(of_rx_irq_name, sizeof(of_rx_irq_name),
                         "rx_%03d", qinst->queue_id);

                qinst->irq = of_irq_get_byname(np, of_rx_irq_name);
                if (qinst->irq < 0) {
                        dev_crit(dev,
                                 "[%d]QID %d PID %d:No IRQ[%s]: %d\n",
                                 idx, qinst->queue_id, qinst->proxy_id,
                                 of_rx_irq_name, qinst->irq);
                        return qinst->irq;
                }
                /* Allocate usage buffer for rx */
                qinst->rx_buff = devm_kzalloc(dev,
                                              d->max_message_size, GFP_KERNEL);
                if (!qinst->rx_buff)
                        return -ENOMEM;
        }

        qinst->queue_buff_start = inst->queue_proxy_region +
            Q_DATA_OFFSET(qinst->proxy_id, qinst->queue_id, d->data_first_reg);
        qinst->queue_buff_end = inst->queue_proxy_region +
            Q_DATA_OFFSET(qinst->proxy_id, qinst->queue_id, d->data_last_reg);
        qinst->queue_state = inst->queue_state_debug_region +
            Q_STATE_OFFSET(qinst->queue_id);
        qinst->chan = chan;

        chan->con_priv = qinst;

        dev_dbg(dev, "[%d] qidx=%d pidx=%d irq=%d q_s=%p q_e = %p\n",
                idx, qinst->queue_id, qinst->proxy_id, qinst->irq,
                qinst->queue_buff_start, qinst->queue_buff_end);
        return 0;
}

/* Queue operations */
static const struct mbox_chan_ops ti_msgmgr_chan_ops = {
        .startup = ti_msgmgr_queue_startup,
        .shutdown = ti_msgmgr_queue_shutdown,
        .peek_data = ti_msgmgr_queue_peek_data,
        .last_tx_done = ti_msgmgr_last_tx_done,
        .send_data = ti_msgmgr_send_data,
};

/* Keystone K2G SoC integration details */
static const struct ti_msgmgr_valid_queue_desc k2g_valid_queues[] = {
        {.queue_id = 0, .proxy_id = 0, .is_tx = true,},
        {.queue_id = 1, .proxy_id = 0, .is_tx = true,},
        {.queue_id = 2, .proxy_id = 0, .is_tx = true,},
        {.queue_id = 3, .proxy_id = 0, .is_tx = true,},
        {.queue_id = 5, .proxy_id = 2, .is_tx = false,},
        {.queue_id = 56, .proxy_id = 1, .is_tx = true,},
        {.queue_id = 57, .proxy_id = 2, .is_tx = false,},
        {.queue_id = 58, .proxy_id = 3, .is_tx = true,},
        {.queue_id = 59, .proxy_id = 4, .is_tx = true,},
        {.queue_id = 60, .proxy_id = 5, .is_tx = true,},
        {.queue_id = 61, .proxy_id = 6, .is_tx = true,},
};

static const struct ti_msgmgr_desc k2g_desc = {
        .queue_count = 64,
        .max_message_size = 64,
        .max_messages = 128,
        .q_slices = 1,
        .q_proxies = 1,
        .data_first_reg = 16,
        .data_last_reg = 31,
        .tx_polled = false,
        .valid_queues = k2g_valid_queues,
        .num_valid_queues = ARRAY_SIZE(k2g_valid_queues),
};

static const struct of_device_id ti_msgmgr_of_match[] = {
        {.compatible = "ti,k2g-message-manager", .data = &k2g_desc},
        { /* Sentinel */ }
};
MODULE_DEVICE_TABLE(of, ti_msgmgr_of_match);

static int ti_msgmgr_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        const struct of_device_id *of_id;
        struct device_node *np;
        struct resource *res;
        const struct ti_msgmgr_desc *desc;
        struct ti_msgmgr_inst *inst;
        struct ti_queue_inst *qinst;
        struct mbox_controller *mbox;
        struct mbox_chan *chans;
        int queue_count;
        int i;
        int ret = -EINVAL;
        const struct ti_msgmgr_valid_queue_desc *queue_desc;

        if (!dev->of_node) {
                dev_err(dev, "no OF information\n");
                return -EINVAL;
        }
        np = dev->of_node;

        of_id = of_match_device(ti_msgmgr_of_match, dev);
        if (!of_id) {
                dev_err(dev, "OF data missing\n");
                return -EINVAL;
        }
        desc = of_id->data;

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

        inst->dev = dev;
        inst->desc = desc;

        res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
                                           "queue_proxy_region");
        inst->queue_proxy_region = devm_ioremap_resource(dev, res);
        if (IS_ERR(inst->queue_proxy_region))
                return PTR_ERR(inst->queue_proxy_region);

        res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
                                           "queue_state_debug_region");
        inst->queue_state_debug_region = devm_ioremap_resource(dev, res);
        if (IS_ERR(inst->queue_state_debug_region))
                return PTR_ERR(inst->queue_state_debug_region);

        dev_dbg(dev, "proxy region=%p, queue_state=%p\n",
                inst->queue_proxy_region, inst->queue_state_debug_region);

        queue_count = desc->num_valid_queues;
        if (!queue_count || queue_count > desc->queue_count) {
                dev_crit(dev, "Invalid Number of queues %d. Max %d\n",
                         queue_count, desc->queue_count);
                return -ERANGE;
        }
        inst->num_valid_queues = queue_count;

        qinst = devm_kzalloc(dev, sizeof(*qinst) * queue_count, GFP_KERNEL);
        if (!qinst)
                return -ENOMEM;
        inst->qinsts = qinst;

        chans = devm_kzalloc(dev, sizeof(*chans) * queue_count, GFP_KERNEL);
        if (!chans)
                return -ENOMEM;
        inst->chans = chans;

        for (i = 0, queue_desc = desc->valid_queues;
             i < queue_count; i++, qinst++, chans++, queue_desc++) {
                ret = ti_msgmgr_queue_setup(i, dev, np, inst,
                                            desc, queue_desc, qinst, chans);
                if (ret)
                        return ret;
        }

        mbox = &inst->mbox;
        mbox->dev = dev;
        mbox->ops = &ti_msgmgr_chan_ops;
        mbox->chans = inst->chans;
        mbox->num_chans = inst->num_valid_queues;
        mbox->txdone_irq = false;
        mbox->txdone_poll = desc->tx_polled;
        if (desc->tx_polled)
                mbox->txpoll_period = desc->tx_poll_timeout_ms;
        mbox->of_xlate = ti_msgmgr_of_xlate;

        platform_set_drvdata(pdev, inst);
        ret = mbox_controller_register(mbox);
        if (ret)
                dev_err(dev, "Failed to register mbox_controller(%d)\n", ret);

        return ret;
}

static int ti_msgmgr_remove(struct platform_device *pdev)
{
        struct ti_msgmgr_inst *inst;

        inst = platform_get_drvdata(pdev);
        mbox_controller_unregister(&inst->mbox);

        return 0;
}

static struct platform_driver ti_msgmgr_driver = {
        .probe = ti_msgmgr_probe,
        .remove = ti_msgmgr_remove,
        .driver = {
                   .name = "ti-msgmgr",
                   .of_match_table = of_match_ptr(ti_msgmgr_of_match),
        },
};
module_platform_driver(ti_msgmgr_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("TI message manager driver");
MODULE_AUTHOR("Nishanth Menon");
MODULE_ALIAS("platform:ti-msgmgr");