remoteproc_virtio.c revision 41a6ee09ee8dd7ac3a6ac12a24e26279b5d93385 
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/rpmsg.h>
23#include <linux/virtio.h>
24#include <linux/virtio_config.h>
25#include <linux/virtio_ids.h>
26#include <linux/virtio_ring.h>
27#include <linux/err.h>
28#include <linux/kref.h>
29#include <linux/slab.h>
30
31#include "remoteproc_internal.h"
32
33/**
34 * struct rproc_virtio_vq_info - virtqueue state
35 * @vq_id: a unique index of this virtqueue (unique for this @rproc)
36 * @rproc: handle to the remote processor
37 *
38 * Such a struct will be maintained for every virtqueue we're
39 * using to communicate with the remote processor
40 */
41struct rproc_virtio_vq_info {
42	__u16 vq_id;
43	struct rproc *rproc;
44};
45
46/* kick the remote processor, and let it know which virtqueue to poke at */
47static void rproc_virtio_notify(struct virtqueue *vq)
48{
49	struct rproc_virtio_vq_info *rpvq = vq->priv;
50	struct rproc *rproc = rpvq->rproc;
51
52	dev_dbg(rproc->dev, "kicking vq id: %d\n", rpvq->vq_id);
53
54	rproc->ops->kick(rproc, rpvq->vq_id);
55}
56
57/**
58 * rproc_vq_interrupt() - tell remoteproc that a virtqueue is interrupted
59 * @rproc: handle to the remote processor
60 * @vq_id: index of the signalled virtqueue
61 *
62 * This function should be called by the platform-specific rproc driver,
63 * when the remote processor signals that a specific virtqueue has pending
64 * messages available.
65 *
66 * Returns IRQ_NONE if no message was found in the @vq_id virtqueue,
67 * and otherwise returns IRQ_HANDLED.
68 */
69irqreturn_t rproc_vq_interrupt(struct rproc *rproc, int vq_id)
70{
71	return vring_interrupt(0, rproc->rvdev->vq[vq_id]);
72}
73EXPORT_SYMBOL(rproc_vq_interrupt);
74
75static struct virtqueue *rp_find_vq(struct virtio_device *vdev,
76				    unsigned id,
77				    void (*callback)(struct virtqueue *vq),
78				    const char *name)
79{
80	struct rproc *rproc = vdev_to_rproc(vdev);
81	struct rproc_vdev *rvdev = rproc->rvdev;
82	struct rproc_virtio_vq_info *rpvq;
83	struct virtqueue *vq;
84	void *addr;
85	int ret, len;
86
87	rpvq = kmalloc(sizeof(*rpvq), GFP_KERNEL);
88	if (!rpvq)
89		return ERR_PTR(-ENOMEM);
90
91	rpvq->rproc = rproc;
92	rpvq->vq_id = id;
93
94	addr = rvdev->vring[id].va;
95	len = rvdev->vring[id].len;
96
97	dev_dbg(rproc->dev, "vring%d: va %p qsz %d\n", id, addr, len);
98
99	/*
100	 * Create the new vq, and tell virtio we're not interested in
101	 * the 'weak' smp barriers, since we're talking with a real device.
102	 */
103	vq = vring_new_virtqueue(len, AMP_VRING_ALIGN, vdev, false, addr,
104					rproc_virtio_notify, callback, name);
105	if (!vq) {
106		dev_err(rproc->dev, "vring_new_virtqueue %s failed\n", name);
107		ret = -ENOMEM;
108		goto free_rpvq;
109	}
110
111	rvdev->vq[id] = vq;
112	vq->priv = rpvq;
113
114	return vq;
115
116free_rpvq:
117	kfree(rpvq);
118	return ERR_PTR(ret);
119}
120
121static void rproc_virtio_del_vqs(struct virtio_device *vdev)
122{
123	struct virtqueue *vq, *n;
124	struct rproc *rproc = vdev_to_rproc(vdev);
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		struct rproc_virtio_vq_info *rpvq = vq->priv;
131		vring_del_virtqueue(vq);
132		kfree(rpvq);
133	}
134}
135
136static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
137		       struct virtqueue *vqs[],
138		       vq_callback_t *callbacks[],
139		       const char *names[])
140{
141	struct rproc *rproc = vdev_to_rproc(vdev);
142	int i, ret;
143
144	/* we maintain two virtqueues per remote processor (for RX and TX) */
145	if (nvqs != 2)
146		return -EINVAL;
147
148	for (i = 0; i < nvqs; ++i) {
149		vqs[i] = rp_find_vq(vdev, i, callbacks[i], names[i]);
150		if (IS_ERR(vqs[i])) {
151			ret = PTR_ERR(vqs[i]);
152			goto error;
153		}
154	}
155
156	/* now that the vqs are all set, boot the remote processor */
157	ret = rproc_boot(rproc);
158	if (ret) {
159		dev_err(rproc->dev, "rproc_boot() failed %d\n", ret);
160		goto error;
161	}
162
163	return 0;
164
165error:
166	rproc_virtio_del_vqs(vdev);
167	return ret;
168}
169
170/*
171 * We don't support yet real virtio status semantics.
172 *
173 * The plan is to provide this via the VIRTIO HDR resource entry
174 * which is part of the firmware: this way the remote processor
175 * will be able to access the status values as set by us.
176 */
177static u8 rproc_virtio_get_status(struct virtio_device *vdev)
178{
179	return 0;
180}
181
182static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
183{
184	dev_dbg(&vdev->dev, "new status: %d\n", status);
185}
186
187static void rproc_virtio_reset(struct virtio_device *vdev)
188{
189	dev_dbg(&vdev->dev, "reset !\n");
190}
191
192/* provide the vdev features as retrieved from the firmware */
193static u32 rproc_virtio_get_features(struct virtio_device *vdev)
194{
195	struct rproc *rproc = vdev_to_rproc(vdev);
196
197	/* we only support a single vdev device for now */
198	return rproc->rvdev->dfeatures;
199}
200
201static void rproc_virtio_finalize_features(struct virtio_device *vdev)
202{
203	struct rproc *rproc = vdev_to_rproc(vdev);
204
205	/* Give virtio_ring a chance to accept features */
206	vring_transport_features(vdev);
207
208	/*
209	 * Remember the finalized features of our vdev, and provide it
210	 * to the remote processor once it is powered on.
211	 *
212	 * Similarly to the status field, we don't expose yet the negotiated
213	 * features to the remote processors at this point. This will be
214	 * fixed as part of a small resource table overhaul and then an
215	 * extension of the virtio resource entries.
216	 */
217	rproc->rvdev->gfeatures = vdev->features[0];
218}
219
220static struct virtio_config_ops rproc_virtio_config_ops = {
221	.get_features	= rproc_virtio_get_features,
222	.finalize_features = rproc_virtio_finalize_features,
223	.find_vqs	= rproc_virtio_find_vqs,
224	.del_vqs	= rproc_virtio_del_vqs,
225	.reset		= rproc_virtio_reset,
226	.set_status	= rproc_virtio_set_status,
227	.get_status	= rproc_virtio_get_status,
228};
229
230/*
231 * This function is called whenever vdev is released, and is responsible
232 * to decrement the remote processor's refcount taken when vdev was
233 * added.
234 *
235 * Never call this function directly; it will be called by the driver
236 * core when needed.
237 */
238static void rproc_vdev_release(struct device *dev)
239{
240	struct virtio_device *vdev = dev_to_virtio(dev);
241	struct rproc *rproc = vdev_to_rproc(vdev);
242
243	kref_put(&rproc->refcount, rproc_release);
244}
245
246/**
247 * rproc_add_rpmsg_vdev() - create an rpmsg virtio device
248 * @rproc: the rproc handle
249 *
250 * This function is called if virtio rpmsg support was found in the
251 * firmware of the remote processor.
252 *
253 * Today we only support creating a single rpmsg vdev (virtio device),
254 * but the plan is to remove this limitation. At that point this interface
255 * will be revised/extended.
256 */
257int rproc_add_rpmsg_vdev(struct rproc *rproc)
258{
259	struct device *dev = rproc->dev;
260	struct rproc_vdev *rvdev = rproc->rvdev;
261	int ret;
262
263	rvdev->vdev.id.device	= VIRTIO_ID_RPMSG,
264	rvdev->vdev.config	= &rproc_virtio_config_ops,
265	rvdev->vdev.dev.parent	= dev;
266	rvdev->vdev.dev.release	= rproc_vdev_release;
267
268	/*
269	 * We're indirectly making a non-temporary copy of the rproc pointer
270	 * here, because drivers probed with this vdev will indirectly
271	 * access the wrapping rproc.
272	 *
273	 * Therefore we must increment the rproc refcount here, and decrement
274	 * it _only_ when the vdev is released.
275	 */
276	kref_get(&rproc->refcount);
277
278	ret = register_virtio_device(&rvdev->vdev);
279	if (ret) {
280		kref_put(&rproc->refcount, rproc_release);
281		dev_err(dev, "failed to register vdev: %d\n", ret);
282	}
283
284	return ret;
285}
286
287/**
288 * rproc_remove_rpmsg_vdev() - remove an rpmsg vdev device
289 * @rproc: the rproc handle
290 *
291 * This function is called whenever @rproc is removed _iff_ an rpmsg
292 * vdev was created beforehand.
293 */
294void rproc_remove_rpmsg_vdev(struct rproc *rproc)
295{
296	struct rproc_vdev *rvdev = rproc->rvdev;
297
298	unregister_virtio_device(&rvdev->vdev);
299}
300