// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.
 */

#include <linux/mhi.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/sock.h>

#include "qrtr.h"

struct qrtr_mhi_dev {
        struct qrtr_endpoint ep;
        struct mhi_device *mhi_dev;
        struct device *dev;
};

/* From MHI to QRTR */
static void qcom_mhi_qrtr_dl_callback(struct mhi_device *mhi_dev,
                                      struct mhi_result *mhi_res)
{
        struct qrtr_mhi_dev *qdev = dev_get_drvdata(&mhi_dev->dev);
        int rc;

        if (!qdev || (mhi_res->transaction_status && mhi_res->transaction_status != -ENOTCONN))
                return;

        /* Channel got reset. So just free the buffer */
        if (mhi_res->transaction_status == -ENOTCONN) {
                devm_kfree(&mhi_dev->dev, mhi_res->buf_addr);
                return;
        }

        rc = qrtr_endpoint_post(&qdev->ep, mhi_res->buf_addr,
                                mhi_res->bytes_xferd);
        if (rc == -EINVAL)
                dev_err(qdev->dev, "invalid ipcrouter packet\n");

        /* Done with the buffer, now recycle it for future use */
        rc = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, mhi_res->buf_addr,
                           mhi_dev->mhi_cntrl->buffer_len, MHI_EOT);
        if (rc)
                dev_err(&mhi_dev->dev, "Failed to recycle the buffer: %d\n", rc);
}

/* From QRTR to MHI */
static void qcom_mhi_qrtr_ul_callback(struct mhi_device *mhi_dev,
                                      struct mhi_result *mhi_res)
{
        struct sk_buff *skb = mhi_res->buf_addr;

        if (skb->sk)
                sock_put(skb->sk);
        consume_skb(skb);
}

/* Send data over MHI */
static int qcom_mhi_qrtr_send(struct qrtr_endpoint *ep, struct sk_buff *skb)
{
        struct qrtr_mhi_dev *qdev = container_of(ep, struct qrtr_mhi_dev, ep);
        int rc;

        if (skb->sk)
                sock_hold(skb->sk);

        rc = skb_linearize(skb);
        if (rc)
                goto free_skb;

        rc = mhi_queue_skb(qdev->mhi_dev, DMA_TO_DEVICE, skb, skb->len,
                           MHI_EOT);
        if (rc)
                goto free_skb;

        return rc;

free_skb:
        if (skb->sk)
                sock_put(skb->sk);
        kfree_skb(skb);

        return rc;
}

static int qcom_mhi_qrtr_queue_dl_buffers(struct mhi_device *mhi_dev)
{
        u32 free_desc;
        void *buf;
        int ret;

        free_desc = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
        while (free_desc--) {
                buf = devm_kmalloc(&mhi_dev->dev, mhi_dev->mhi_cntrl->buffer_len, GFP_KERNEL);
                if (!buf)
                        return -ENOMEM;

                ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, buf, mhi_dev->mhi_cntrl->buffer_len,
                                    MHI_EOT);
                if (ret) {
                        dev_err(&mhi_dev->dev, "Failed to queue buffer: %d\n", ret);
                        return ret;
                }
        }

        return 0;
}

static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev,
                               const struct mhi_device_id *id)
{
        struct qrtr_mhi_dev *qdev;
        int rc;

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

        qdev->mhi_dev = mhi_dev;
        qdev->dev = &mhi_dev->dev;
        qdev->ep.xmit = qcom_mhi_qrtr_send;

        dev_set_drvdata(&mhi_dev->dev, qdev);

        /* start channels */
        rc = mhi_prepare_for_transfer(mhi_dev);
        if (rc)
                return rc;

        rc = qrtr_endpoint_register(&qdev->ep, QRTR_EP_NID_AUTO);
        if (rc)
                goto err_unprepare;

        rc = qcom_mhi_qrtr_queue_dl_buffers(mhi_dev);
        if (rc)
                goto err_unregister;

        dev_dbg(qdev->dev, "Qualcomm MHI QRTR driver probed\n");

        return 0;

err_unregister:
        qrtr_endpoint_unregister(&qdev->ep);
err_unprepare:
        mhi_unprepare_from_transfer(mhi_dev);

        return rc;
}

static void qcom_mhi_qrtr_remove(struct mhi_device *mhi_dev)
{
        struct qrtr_mhi_dev *qdev = dev_get_drvdata(&mhi_dev->dev);

        qrtr_endpoint_unregister(&qdev->ep);
        mhi_unprepare_from_transfer(mhi_dev);
        dev_set_drvdata(&mhi_dev->dev, NULL);
}

static const struct mhi_device_id qcom_mhi_qrtr_id_table[] = {
        { .chan = "IPCR" },
        {}
};
MODULE_DEVICE_TABLE(mhi, qcom_mhi_qrtr_id_table);

static int __maybe_unused qcom_mhi_qrtr_pm_suspend_late(struct device *dev)
{
        struct mhi_device *mhi_dev = container_of(dev, struct mhi_device, dev);
        enum mhi_state state;

        state = mhi_get_mhi_state(mhi_dev->mhi_cntrl);
        /*
         * If the device is in suspend state, then no need for the
         * client driver to unprepare the channels.
         */
        if (state == MHI_STATE_M3)
                return 0;

        mhi_unprepare_from_transfer(mhi_dev);

        return 0;
}

static int __maybe_unused qcom_mhi_qrtr_pm_resume_early(struct device *dev)
{
        struct mhi_device *mhi_dev = container_of(dev, struct mhi_device, dev);
        enum mhi_state state;
        int rc;

        state = mhi_get_mhi_state(mhi_dev->mhi_cntrl);
        /*
         * If the device is in suspend state, we won't unprepare channels
         * in suspend callback, therefore no need to prepare channels when
         * resume.
         */
        if (state == MHI_STATE_M3)
                return 0;

        rc = mhi_prepare_for_transfer(mhi_dev);
        if (rc) {
                dev_err(dev, "failed to prepare for autoqueue transfer %d\n", rc);
                return rc;
        }

        return qcom_mhi_qrtr_queue_dl_buffers(mhi_dev);
}

static const struct dev_pm_ops qcom_mhi_qrtr_pm_ops = {
        SET_LATE_SYSTEM_SLEEP_PM_OPS(qcom_mhi_qrtr_pm_suspend_late,
                                     qcom_mhi_qrtr_pm_resume_early)
};

static struct mhi_driver qcom_mhi_qrtr_driver = {
        .probe = qcom_mhi_qrtr_probe,
        .remove = qcom_mhi_qrtr_remove,
        .dl_xfer_cb = qcom_mhi_qrtr_dl_callback,
        .ul_xfer_cb = qcom_mhi_qrtr_ul_callback,
        .id_table = qcom_mhi_qrtr_id_table,
        .driver = {
                .name = "qcom_mhi_qrtr",
                .pm = &qcom_mhi_qrtr_pm_ops,
        },
};

module_mhi_driver(qcom_mhi_qrtr_driver);

MODULE_AUTHOR("Chris Lew <clew@codeaurora.org>");
MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
MODULE_DESCRIPTION("Qualcomm IPC-Router MHI interface driver");
MODULE_LICENSE("GPL v2");