remoteproc_virtio.c

Go to the documentation of this file.

/*
 * Remote processor messaging transport (OMAP platform-specific bits)
 *
 * Copyright (C) 2011 Texas Instruments, Inc.
 * Copyright (C) 2011 Google, Inc.
 *
 * Ohad Ben-Cohen <[email protected]>
 * Brian Swetland <[email protected]>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/export.h>
#include <linux/remoteproc.h>
#include <linux/virtio.h>
#include <linux/virtio_config.h>
#include <linux/virtio_ids.h>
#include <linux/virtio_ring.h>
#include <linux/err.h>
#include <linux/kref.h>
#include <linux/slab.h>

#include "remoteproc_internal.h"

/* kick the remote processor, and let it know which virtqueue to poke at */
static void rproc_virtio_notify(struct virtqueue *vq)
{
    struct rproc_vring *rvring = vq->priv;
    struct rproc *rproc = rvring->rvdev->rproc;
    int notifyid = rvring->notifyid;

    dev_dbg(&rproc->dev, "kicking vq index: %d\n", notifyid);

    rproc->ops->kick(rproc, notifyid);
}

irqreturn_t rproc_vq_interrupt(struct rproc *rproc, int notifyid)
{
    struct rproc_vring *rvring;

    dev_dbg(&rproc->dev, "vq index %d is interrupted\n", notifyid);

    rvring = idr_find(&rproc->notifyids, notifyid);
    if (!rvring || !rvring->vq)
        return IRQ_NONE;

    return vring_interrupt(0, rvring->vq);
}
EXPORT_SYMBOL(rproc_vq_interrupt);

static struct virtqueue *rp_find_vq(struct virtio_device *vdev,
                    unsigned id,
                    void (*callback)(struct virtqueue *vq),
                    const char *name)
{
    struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
    struct rproc *rproc = vdev_to_rproc(vdev);
    struct device *dev = &rproc->dev;
    struct rproc_vring *rvring;
    struct virtqueue *vq;
    void *addr;
    int len, size, ret;

    /* we're temporarily limited to two virtqueues per rvdev */
    if (id >= ARRAY_SIZE(rvdev->vring))
        return ERR_PTR(-EINVAL);

    if (!name)
        return NULL;

    ret = rproc_alloc_vring(rvdev, id);
    if (ret)
        return ERR_PTR(ret);

    rvring = &rvdev->vring[id];
    addr = rvring->va;
    len = rvring->len;

    /* zero vring */
    size = vring_size(len, rvring->align);
    memset(addr, 0, size);

    dev_dbg(dev, "vring%d: va %p qsz %d notifyid %d\n",
                    id, addr, len, rvring->notifyid);

    /*
     * Create the new vq, and tell virtio we're not interested in
     * the 'weak' smp barriers, since we're talking with a real device.
     */
    vq = vring_new_virtqueue(id, len, rvring->align, vdev, false, addr,
                    rproc_virtio_notify, callback, name);
    if (!vq) {
        dev_err(dev, "vring_new_virtqueue %s failed\n", name);
        rproc_free_vring(rvring);
        return ERR_PTR(-ENOMEM);
    }

    rvring->vq = vq;
    vq->priv = rvring;

    return vq;
}

static void __rproc_virtio_del_vqs(struct virtio_device *vdev)
{
    struct virtqueue *vq, *n;
    struct rproc_vring *rvring;

    list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
        rvring = vq->priv;
        rvring->vq = NULL;
        vring_del_virtqueue(vq);
        rproc_free_vring(rvring);
    }
}

static void rproc_virtio_del_vqs(struct virtio_device *vdev)
{
    struct rproc *rproc = vdev_to_rproc(vdev);

    /* power down the remote processor before deleting vqs */
    rproc_shutdown(rproc);

    __rproc_virtio_del_vqs(vdev);
}

static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
               struct virtqueue *vqs[],
               vq_callback_t *callbacks[],
               const char *names[])
{
    struct rproc *rproc = vdev_to_rproc(vdev);
    int i, ret;

    for (i = 0; i < nvqs; ++i) {
        vqs[i] = rp_find_vq(vdev, i, callbacks[i], names[i]);
        if (IS_ERR(vqs[i])) {
            ret = PTR_ERR(vqs[i]);
            goto error;
        }
    }

    /* now that the vqs are all set, boot the remote processor */
    ret = rproc_boot(rproc);
    if (ret) {
        dev_err(&rproc->dev, "rproc_boot() failed %d\n", ret);
        goto error;
    }

    return 0;

error:
    __rproc_virtio_del_vqs(vdev);
    return ret;
}

/*
 * We don't support yet real virtio status semantics.
 *
 * The plan is to provide this via the VDEV resource entry
 * which is part of the firmware: this way the remote processor
 * will be able to access the status values as set by us.
 */
static u8 rproc_virtio_get_status(struct virtio_device *vdev)
{
    return 0;
}

static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
{
    dev_dbg(&vdev->dev, "status: %d\n", status);
}

static void rproc_virtio_reset(struct virtio_device *vdev)
{
    dev_dbg(&vdev->dev, "reset !\n");
}

/* provide the vdev features as retrieved from the firmware */
static u32 rproc_virtio_get_features(struct virtio_device *vdev)
{
    struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);

    return rvdev->dfeatures;
}

static void rproc_virtio_finalize_features(struct virtio_device *vdev)
{
    struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);

    /* Give virtio_ring a chance to accept features */
    vring_transport_features(vdev);

    /*
     * Remember the finalized features of our vdev, and provide it
     * to the remote processor once it is powered on.
     *
     * Similarly to the status field, we don't expose yet the negotiated
     * features to the remote processors at this point. This will be
     * fixed as part of a small resource table overhaul and then an
     * extension of the virtio resource entries.
     */
    rvdev->gfeatures = vdev->features[0];
}

static struct virtio_config_ops rproc_virtio_config_ops = {
    .get_features   = rproc_virtio_get_features,
    .finalize_features = rproc_virtio_finalize_features,
    .find_vqs   = rproc_virtio_find_vqs,
    .del_vqs    = rproc_virtio_del_vqs,
    .reset      = rproc_virtio_reset,
    .set_status = rproc_virtio_set_status,
    .get_status = rproc_virtio_get_status,
};

/*
 * This function is called whenever vdev is released, and is responsible
 * to decrement the remote processor's refcount which was taken when vdev was
 * added.
 *
 * Never call this function directly; it will be called by the driver
 * core when needed.
 */
static void rproc_vdev_release(struct device *dev)
{
    struct virtio_device *vdev = dev_to_virtio(dev);
    struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
    struct rproc *rproc = vdev_to_rproc(vdev);

    list_del(&rvdev->node);
    kfree(rvdev);

    put_device(&rproc->dev);
}

int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
{
    struct rproc *rproc = rvdev->rproc;
    struct device *dev = &rproc->dev;
    struct virtio_device *vdev = &rvdev->vdev;
    int ret;

    vdev->id.device = id,
    vdev->config = &rproc_virtio_config_ops,
    vdev->dev.parent = dev;
    vdev->dev.release = rproc_vdev_release;

    /*
     * We're indirectly making a non-temporary copy of the rproc pointer
     * here, because drivers probed with this vdev will indirectly
     * access the wrapping rproc.
     *
     * Therefore we must increment the rproc refcount here, and decrement
     * it _only_ when the vdev is released.
     */
    get_device(&rproc->dev);

    ret = register_virtio_device(vdev);
    if (ret) {
        put_device(&rproc->dev);
        dev_err(dev, "failed to register vdev: %d\n", ret);
        goto out;
    }

    dev_info(dev, "registered %s (type %d)\n", dev_name(&vdev->dev), id);

out:
    return ret;
}

void rproc_remove_virtio_dev(struct rproc_vdev *rvdev)
{
    unregister_virtio_device(&rvdev->vdev);
}