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 */
33 static 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  */
56 irqreturn_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 }
68 EXPORT_SYMBOL(rproc_vq_interrupt);
69 
70 static 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 	if (!name)
88 		return NULL;
89 
90 	ret = rproc_alloc_vring(rvdev, id);
91 	if (ret)
92 		return ERR_PTR(ret);
93 
94 	rvring = &rvdev->vring[id];
95 	addr = rvring->va;
96 	len = rvring->len;
97 
98 	/* zero vring */
99 	size = vring_size(len, rvring->align);
100 	memset(addr, 0, size);
101 
102 	dev_dbg(dev, "vring%d: va %p qsz %d notifyid %d\n",
103 					id, addr, len, rvring->notifyid);
104 
105 	/*
106 	 * Create the new vq, and tell virtio we're not interested in
107 	 * the 'weak' smp barriers, since we're talking with a real device.
108 	 */
109 	vq = vring_new_virtqueue(id, len, rvring->align, vdev, false, addr,
110 					rproc_virtio_notify, callback, name);
111 	if (!vq) {
112 		dev_err(dev, "vring_new_virtqueue %s failed\n", name);
113 		rproc_free_vring(rvring);
114 		return ERR_PTR(-ENOMEM);
115 	}
116 
117 	rvring->vq = vq;
118 	vq->priv = rvring;
119 
120 	return vq;
121 }
122 
123 static void __rproc_virtio_del_vqs(struct virtio_device *vdev)
124 {
125 	struct virtqueue *vq, *n;
126 	struct rproc_vring *rvring;
127 
128 	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
129 		rvring = vq->priv;
130 		rvring->vq = NULL;
131 		vring_del_virtqueue(vq);
132 		rproc_free_vring(rvring);
133 	}
134 }
135 
136 static void rproc_virtio_del_vqs(struct virtio_device *vdev)
137 {
138 	struct rproc *rproc = vdev_to_rproc(vdev);
139 
140 	/* power down the remote processor before deleting vqs */
141 	rproc_shutdown(rproc);
142 
143 	__rproc_virtio_del_vqs(vdev);
144 }
145 
146 static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
147 		       struct virtqueue *vqs[],
148 		       vq_callback_t *callbacks[],
149 		       const char *names[])
150 {
151 	struct rproc *rproc = vdev_to_rproc(vdev);
152 	int i, ret;
153 
154 	for (i = 0; i < nvqs; ++i) {
155 		vqs[i] = rp_find_vq(vdev, i, callbacks[i], names[i]);
156 		if (IS_ERR(vqs[i])) {
157 			ret = PTR_ERR(vqs[i]);
158 			goto error;
159 		}
160 	}
161 
162 	/* now that the vqs are all set, boot the remote processor */
163 	ret = rproc_boot(rproc);
164 	if (ret) {
165 		dev_err(&rproc->dev, "rproc_boot() failed %d\n", ret);
166 		goto error;
167 	}
168 
169 	return 0;
170 
171 error:
172 	__rproc_virtio_del_vqs(vdev);
173 	return ret;
174 }
175 
176 static u8 rproc_virtio_get_status(struct virtio_device *vdev)
177 {
178 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
179 	struct fw_rsc_vdev *rsc;
180 
181 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
182 
183 	return rsc->status;
184 }
185 
186 static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
187 {
188 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
189 	struct fw_rsc_vdev *rsc;
190 
191 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
192 
193 	rsc->status = status;
194 	dev_dbg(&vdev->dev, "status: %d\n", status);
195 }
196 
197 static void rproc_virtio_reset(struct virtio_device *vdev)
198 {
199 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
200 	struct fw_rsc_vdev *rsc;
201 
202 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
203 
204 	rsc->status = 0;
205 	dev_dbg(&vdev->dev, "reset !\n");
206 }
207 
208 /* provide the vdev features as retrieved from the firmware */
209 static u32 rproc_virtio_get_features(struct virtio_device *vdev)
210 {
211 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
212 	struct fw_rsc_vdev *rsc;
213 
214 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
215 
216 	return rsc->dfeatures;
217 }
218 
219 static void rproc_virtio_finalize_features(struct virtio_device *vdev)
220 {
221 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
222 	struct fw_rsc_vdev *rsc;
223 
224 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
225 
226 	/* Give virtio_ring a chance to accept features */
227 	vring_transport_features(vdev);
228 
229 	/*
230 	 * Remember the finalized features of our vdev, and provide it
231 	 * to the remote processor once it is powered on.
232 	 */
233 	rsc->gfeatures = vdev->features[0];
234 }
235 
236 static void rproc_virtio_get(struct virtio_device *vdev, unsigned offset,
237 							void *buf, unsigned len)
238 {
239 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
240 	struct fw_rsc_vdev *rsc;
241 	void *cfg;
242 
243 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
244 	cfg = &rsc->vring[rsc->num_of_vrings];
245 
246 	if (offset + len > rsc->config_len || offset + len < len) {
247 		dev_err(&vdev->dev, "rproc_virtio_get: access out of bounds\n");
248 		return;
249 	}
250 
251 	memcpy(buf, cfg + offset, len);
252 }
253 
254 static void rproc_virtio_set(struct virtio_device *vdev, unsigned offset,
255 		      const void *buf, unsigned len)
256 {
257 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
258 	struct fw_rsc_vdev *rsc;
259 	void *cfg;
260 
261 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
262 	cfg = &rsc->vring[rsc->num_of_vrings];
263 
264 	if (offset + len > rsc->config_len || offset + len < len) {
265 		dev_err(&vdev->dev, "rproc_virtio_set: access out of bounds\n");
266 		return;
267 	}
268 
269 	memcpy(cfg + offset, buf, len);
270 }
271 
272 static const struct virtio_config_ops rproc_virtio_config_ops = {
273 	.get_features	= rproc_virtio_get_features,
274 	.finalize_features = rproc_virtio_finalize_features,
275 	.find_vqs	= rproc_virtio_find_vqs,
276 	.del_vqs	= rproc_virtio_del_vqs,
277 	.reset		= rproc_virtio_reset,
278 	.set_status	= rproc_virtio_set_status,
279 	.get_status	= rproc_virtio_get_status,
280 	.get		= rproc_virtio_get,
281 	.set		= rproc_virtio_set,
282 };
283 
284 /*
285  * This function is called whenever vdev is released, and is responsible
286  * to decrement the remote processor's refcount which was taken when vdev was
287  * added.
288  *
289  * Never call this function directly; it will be called by the driver
290  * core when needed.
291  */
292 static void rproc_vdev_release(struct device *dev)
293 {
294 	struct virtio_device *vdev = dev_to_virtio(dev);
295 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
296 	struct rproc *rproc = vdev_to_rproc(vdev);
297 
298 	list_del(&rvdev->node);
299 	kfree(rvdev);
300 
301 	put_device(&rproc->dev);
302 }
303 
304 /**
305  * rproc_add_virtio_dev() - register an rproc-induced virtio device
306  * @rvdev: the remote vdev
307  *
308  * This function registers a virtio device. This vdev's partent is
309  * the rproc device.
310  *
311  * Returns 0 on success or an appropriate error value otherwise.
312  */
313 int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
314 {
315 	struct rproc *rproc = rvdev->rproc;
316 	struct device *dev = &rproc->dev;
317 	struct virtio_device *vdev = &rvdev->vdev;
318 	int ret;
319 
320 	vdev->id.device	= id,
321 	vdev->config = &rproc_virtio_config_ops,
322 	vdev->dev.parent = dev;
323 	vdev->dev.release = rproc_vdev_release;
324 
325 	/*
326 	 * We're indirectly making a non-temporary copy of the rproc pointer
327 	 * here, because drivers probed with this vdev will indirectly
328 	 * access the wrapping rproc.
329 	 *
330 	 * Therefore we must increment the rproc refcount here, and decrement
331 	 * it _only_ when the vdev is released.
332 	 */
333 	get_device(&rproc->dev);
334 
335 	ret = register_virtio_device(vdev);
336 	if (ret) {
337 		put_device(&rproc->dev);
338 		dev_err(dev, "failed to register vdev: %d\n", ret);
339 		goto out;
340 	}
341 
342 	dev_info(dev, "registered %s (type %d)\n", dev_name(&vdev->dev), id);
343 
344 out:
345 	return ret;
346 }
347 
348 /**
349  * rproc_remove_virtio_dev() - remove an rproc-induced virtio device
350  * @rvdev: the remote vdev
351  *
352  * This function unregisters an existing virtio device.
353  */
354 void rproc_remove_virtio_dev(struct rproc_vdev *rvdev)
355 {
356 	unregister_virtio_device(&rvdev->vdev);
357 }
358