Root/drivers/remoteproc/remoteproc_virtio.c

1/*
2 * Remote processor messaging transport (OMAP platform-specific bits)
3 *
4 * Copyright (C) 2011 Texas Instruments, Inc.
5 * Copyright (C) 2011 Google, Inc.
6 *
7 * Ohad Ben-Cohen <ohad@wizery.com>
8 * Brian Swetland <swetland@google.com>
9 *
10 * This software is licensed under the terms of the GNU General Public
11 * License version 2, as published by the Free Software Foundation, and
12 * may be copied, distributed, and modified under those terms.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 */
19
20#include <linux/export.h>
21#include <linux/remoteproc.h>
22#include <linux/virtio.h>
23#include <linux/virtio_config.h>
24#include <linux/virtio_ids.h>
25#include <linux/virtio_ring.h>
26#include <linux/err.h>
27#include <linux/kref.h>
28#include <linux/slab.h>
29
30#include "remoteproc_internal.h"
31
32/* kick the remote processor, and let it know which virtqueue to poke at */
33static void rproc_virtio_notify(struct virtqueue *vq)
34{
35    struct rproc_vring *rvring = vq->priv;
36    struct rproc *rproc = rvring->rvdev->rproc;
37    int notifyid = rvring->notifyid;
38
39    dev_dbg(&rproc->dev, "kicking vq index: %d\n", notifyid);
40
41    rproc->ops->kick(rproc, notifyid);
42}
43
44/**
45 * rproc_vq_interrupt() - tell remoteproc that a virtqueue is interrupted
46 * @rproc: handle to the remote processor
47 * @notifyid: index of the signalled virtqueue (unique per this @rproc)
48 *
49 * This function should be called by the platform-specific rproc driver,
50 * when the remote processor signals that a specific virtqueue has pending
51 * messages available.
52 *
53 * Returns IRQ_NONE if no message was found in the @notifyid virtqueue,
54 * and otherwise returns IRQ_HANDLED.
55 */
56irqreturn_t rproc_vq_interrupt(struct rproc *rproc, int notifyid)
57{
58    struct rproc_vring *rvring;
59
60    dev_dbg(&rproc->dev, "vq index %d is interrupted\n", notifyid);
61
62    rvring = idr_find(&rproc->notifyids, notifyid);
63    if (!rvring || !rvring->vq)
64        return IRQ_NONE;
65
66    return vring_interrupt(0, rvring->vq);
67}
68EXPORT_SYMBOL(rproc_vq_interrupt);
69
70static struct virtqueue *rp_find_vq(struct virtio_device *vdev,
71                    unsigned id,
72                    void (*callback)(struct virtqueue *vq),
73                    const char *name)
74{
75    struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
76    struct rproc *rproc = vdev_to_rproc(vdev);
77    struct device *dev = &rproc->dev;
78    struct rproc_vring *rvring;
79    struct virtqueue *vq;
80    void *addr;
81    int len, size, ret;
82
83    /* we're temporarily limited to two virtqueues per rvdev */
84    if (id >= ARRAY_SIZE(rvdev->vring))
85        return ERR_PTR(-EINVAL);
86
87    ret = rproc_alloc_vring(rvdev, id);
88    if (ret)
89        return ERR_PTR(ret);
90
91    rvring = &rvdev->vring[id];
92    addr = rvring->va;
93    len = rvring->len;
94
95    /* zero vring */
96    size = vring_size(len, rvring->align);
97    memset(addr, 0, size);
98
99    dev_dbg(dev, "vring%d: va %p qsz %d notifyid %d\n",
100                    id, addr, len, rvring->notifyid);
101
102    /*
103     * Create the new vq, and tell virtio we're not interested in
104     * the 'weak' smp barriers, since we're talking with a real device.
105     */
106    vq = vring_new_virtqueue(len, rvring->align, vdev, false, addr,
107                    rproc_virtio_notify, callback, name);
108    if (!vq) {
109        dev_err(dev, "vring_new_virtqueue %s failed\n", name);
110        rproc_free_vring(rvring);
111        return ERR_PTR(-ENOMEM);
112    }
113
114    rvring->vq = vq;
115    vq->priv = rvring;
116
117    return vq;
118}
119
120static void rproc_virtio_del_vqs(struct virtio_device *vdev)
121{
122    struct virtqueue *vq, *n;
123    struct rproc *rproc = vdev_to_rproc(vdev);
124    struct rproc_vring *rvring;
125
126    /* power down the remote processor before deleting vqs */
127    rproc_shutdown(rproc);
128
129    list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
130        rvring = vq->priv;
131        rvring->vq = NULL;
132        vring_del_virtqueue(vq);
133        rproc_free_vring(rvring);
134    }
135}
136
137static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
138               struct virtqueue *vqs[],
139               vq_callback_t *callbacks[],
140               const char *names[])
141{
142    struct rproc *rproc = vdev_to_rproc(vdev);
143    int i, ret;
144
145    for (i = 0; i < nvqs; ++i) {
146        vqs[i] = rp_find_vq(vdev, i, callbacks[i], names[i]);
147        if (IS_ERR(vqs[i])) {
148            ret = PTR_ERR(vqs[i]);
149            goto error;
150        }
151    }
152
153    /* now that the vqs are all set, boot the remote processor */
154    ret = rproc_boot(rproc);
155    if (ret) {
156        dev_err(&rproc->dev, "rproc_boot() failed %d\n", ret);
157        goto error;
158    }
159
160    return 0;
161
162error:
163    rproc_virtio_del_vqs(vdev);
164    return ret;
165}
166
167/*
168 * We don't support yet real virtio status semantics.
169 *
170 * The plan is to provide this via the VDEV resource entry
171 * which is part of the firmware: this way the remote processor
172 * will be able to access the status values as set by us.
173 */
174static u8 rproc_virtio_get_status(struct virtio_device *vdev)
175{
176    return 0;
177}
178
179static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
180{
181    dev_dbg(&vdev->dev, "status: %d\n", status);
182}
183
184static void rproc_virtio_reset(struct virtio_device *vdev)
185{
186    dev_dbg(&vdev->dev, "reset !\n");
187}
188
189/* provide the vdev features as retrieved from the firmware */
190static u32 rproc_virtio_get_features(struct virtio_device *vdev)
191{
192    struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
193
194    return rvdev->dfeatures;
195}
196
197static void rproc_virtio_finalize_features(struct virtio_device *vdev)
198{
199    struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
200
201    /* Give virtio_ring a chance to accept features */
202    vring_transport_features(vdev);
203
204    /*
205     * Remember the finalized features of our vdev, and provide it
206     * to the remote processor once it is powered on.
207     *
208     * Similarly to the status field, we don't expose yet the negotiated
209     * features to the remote processors at this point. This will be
210     * fixed as part of a small resource table overhaul and then an
211     * extension of the virtio resource entries.
212     */
213    rvdev->gfeatures = vdev->features[0];
214}
215
216static struct virtio_config_ops rproc_virtio_config_ops = {
217    .get_features = rproc_virtio_get_features,
218    .finalize_features = rproc_virtio_finalize_features,
219    .find_vqs = rproc_virtio_find_vqs,
220    .del_vqs = rproc_virtio_del_vqs,
221    .reset = rproc_virtio_reset,
222    .set_status = rproc_virtio_set_status,
223    .get_status = rproc_virtio_get_status,
224};
225
226/*
227 * This function is called whenever vdev is released, and is responsible
228 * to decrement the remote processor's refcount which was taken when vdev was
229 * added.
230 *
231 * Never call this function directly; it will be called by the driver
232 * core when needed.
233 */
234static void rproc_vdev_release(struct device *dev)
235{
236    struct virtio_device *vdev = dev_to_virtio(dev);
237    struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
238    struct rproc *rproc = vdev_to_rproc(vdev);
239
240    list_del(&rvdev->node);
241    kfree(rvdev);
242
243    put_device(&rproc->dev);
244}
245
246/**
247 * rproc_add_virtio_dev() - register an rproc-induced virtio device
248 * @rvdev: the remote vdev
249 *
250 * This function registers a virtio device. This vdev's partent is
251 * the rproc device.
252 *
253 * Returns 0 on success or an appropriate error value otherwise.
254 */
255int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
256{
257    struct rproc *rproc = rvdev->rproc;
258    struct device *dev = &rproc->dev;
259    struct virtio_device *vdev = &rvdev->vdev;
260    int ret;
261
262    vdev->id.device = id,
263    vdev->config = &rproc_virtio_config_ops,
264    vdev->dev.parent = dev;
265    vdev->dev.release = rproc_vdev_release;
266
267    /*
268     * We're indirectly making a non-temporary copy of the rproc pointer
269     * here, because drivers probed with this vdev will indirectly
270     * access the wrapping rproc.
271     *
272     * Therefore we must increment the rproc refcount here, and decrement
273     * it _only_ when the vdev is released.
274     */
275    get_device(&rproc->dev);
276
277    ret = register_virtio_device(vdev);
278    if (ret) {
279        put_device(&rproc->dev);
280        dev_err(dev, "failed to register vdev: %d\n", ret);
281        goto out;
282    }
283
284    dev_info(dev, "registered %s (type %d)\n", dev_name(&vdev->dev), id);
285
286out:
287    return ret;
288}
289
290/**
291 * rproc_remove_virtio_dev() - remove an rproc-induced virtio device
292 * @rvdev: the remote vdev
293 *
294 * This function unregisters an existing virtio device.
295 */
296void rproc_remove_virtio_dev(struct rproc_vdev *rvdev)
297{
298    unregister_virtio_device(&rvdev->vdev);
299}
300

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