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 bool 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 	return true;
43 }
44 
45 /**
46  * rproc_vq_interrupt() - tell remoteproc that a virtqueue is interrupted
47  * @rproc: handle to the remote processor
48  * @notifyid: index of the signalled virtqueue (unique per this @rproc)
49  *
50  * This function should be called by the platform-specific rproc driver,
51  * when the remote processor signals that a specific virtqueue has pending
52  * messages available.
53  *
54  * Returns IRQ_NONE if no message was found in the @notifyid virtqueue,
55  * and otherwise returns IRQ_HANDLED.
56  */
57 irqreturn_t rproc_vq_interrupt(struct rproc *rproc, int notifyid)
58 {
59 	struct rproc_vring *rvring;
60 
61 	dev_dbg(&rproc->dev, "vq index %d is interrupted\n", notifyid);
62 
63 	rvring = idr_find(&rproc->notifyids, notifyid);
64 	if (!rvring || !rvring->vq)
65 		return IRQ_NONE;
66 
67 	return vring_interrupt(0, rvring->vq);
68 }
69 EXPORT_SYMBOL(rproc_vq_interrupt);
70 
71 static struct virtqueue *rp_find_vq(struct virtio_device *vdev,
72 				    unsigned id,
73 				    void (*callback)(struct virtqueue *vq),
74 				    const char *name)
75 {
76 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
77 	struct rproc *rproc = vdev_to_rproc(vdev);
78 	struct device *dev = &rproc->dev;
79 	struct rproc_vring *rvring;
80 	struct virtqueue *vq;
81 	void *addr;
82 	int len, size, ret;
83 
84 	/* we're temporarily limited to two virtqueues per rvdev */
85 	if (id >= ARRAY_SIZE(rvdev->vring))
86 		return ERR_PTR(-EINVAL);
87 
88 	if (!name)
89 		return NULL;
90 
91 	ret = rproc_alloc_vring(rvdev, id);
92 	if (ret)
93 		return ERR_PTR(ret);
94 
95 	rvring = &rvdev->vring[id];
96 	addr = rvring->va;
97 	len = rvring->len;
98 
99 	/* zero vring */
100 	size = vring_size(len, rvring->align);
101 	memset(addr, 0, size);
102 
103 	dev_dbg(dev, "vring%d: va %p qsz %d notifyid %d\n",
104 					id, addr, len, rvring->notifyid);
105 
106 	/*
107 	 * Create the new vq, and tell virtio we're not interested in
108 	 * the 'weak' smp barriers, since we're talking with a real device.
109 	 */
110 	vq = vring_new_virtqueue(id, len, rvring->align, vdev, false, addr,
111 					rproc_virtio_notify, callback, name);
112 	if (!vq) {
113 		dev_err(dev, "vring_new_virtqueue %s failed\n", name);
114 		rproc_free_vring(rvring);
115 		return ERR_PTR(-ENOMEM);
116 	}
117 
118 	rvring->vq = vq;
119 	vq->priv = rvring;
120 
121 	return vq;
122 }
123 
124 static void __rproc_virtio_del_vqs(struct virtio_device *vdev)
125 {
126 	struct virtqueue *vq, *n;
127 	struct rproc_vring *rvring;
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 
137 static void rproc_virtio_del_vqs(struct virtio_device *vdev)
138 {
139 	struct rproc *rproc = vdev_to_rproc(vdev);
140 
141 	/* power down the remote processor before deleting vqs */
142 	rproc_shutdown(rproc);
143 
144 	__rproc_virtio_del_vqs(vdev);
145 }
146 
147 static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
148 		       struct virtqueue *vqs[],
149 		       vq_callback_t *callbacks[],
150 		       const char * const names[])
151 {
152 	struct rproc *rproc = vdev_to_rproc(vdev);
153 	int i, ret;
154 
155 	for (i = 0; i < nvqs; ++i) {
156 		vqs[i] = rp_find_vq(vdev, i, callbacks[i], names[i]);
157 		if (IS_ERR(vqs[i])) {
158 			ret = PTR_ERR(vqs[i]);
159 			goto error;
160 		}
161 	}
162 
163 	/* now that the vqs are all set, boot the remote processor */
164 	ret = rproc_boot_nowait(rproc);
165 	if (ret) {
166 		dev_err(&rproc->dev, "rproc_boot() failed %d\n", ret);
167 		goto error;
168 	}
169 
170 	return 0;
171 
172 error:
173 	__rproc_virtio_del_vqs(vdev);
174 	return ret;
175 }
176 
177 static u8 rproc_virtio_get_status(struct virtio_device *vdev)
178 {
179 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
180 	struct fw_rsc_vdev *rsc;
181 
182 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
183 
184 	return rsc->status;
185 }
186 
187 static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
188 {
189 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
190 	struct fw_rsc_vdev *rsc;
191 
192 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
193 
194 	rsc->status = status;
195 	dev_dbg(&vdev->dev, "status: %d\n", status);
196 }
197 
198 static void rproc_virtio_reset(struct virtio_device *vdev)
199 {
200 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
201 	struct fw_rsc_vdev *rsc;
202 
203 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
204 
205 	rsc->status = 0;
206 	dev_dbg(&vdev->dev, "reset !\n");
207 }
208 
209 /* provide the vdev features as retrieved from the firmware */
210 static u64 rproc_virtio_get_features(struct virtio_device *vdev)
211 {
212 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
213 	struct fw_rsc_vdev *rsc;
214 
215 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
216 
217 	return rsc->dfeatures;
218 }
219 
220 static int rproc_virtio_finalize_features(struct virtio_device *vdev)
221 {
222 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
223 	struct fw_rsc_vdev *rsc;
224 
225 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
226 
227 	/* Give virtio_ring a chance to accept features */
228 	vring_transport_features(vdev);
229 
230 	/* Make sure we don't have any features > 32 bits! */
231 	BUG_ON((u32)vdev->features != vdev->features);
232 
233 	/*
234 	 * Remember the finalized features of our vdev, and provide it
235 	 * to the remote processor once it is powered on.
236 	 */
237 	rsc->gfeatures = vdev->features;
238 
239 	return 0;
240 }
241 
242 static void rproc_virtio_get(struct virtio_device *vdev, unsigned offset,
243 							void *buf, unsigned len)
244 {
245 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
246 	struct fw_rsc_vdev *rsc;
247 	void *cfg;
248 
249 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
250 	cfg = &rsc->vring[rsc->num_of_vrings];
251 
252 	if (offset + len > rsc->config_len || offset + len < len) {
253 		dev_err(&vdev->dev, "rproc_virtio_get: access out of bounds\n");
254 		return;
255 	}
256 
257 	memcpy(buf, cfg + offset, len);
258 }
259 
260 static void rproc_virtio_set(struct virtio_device *vdev, unsigned offset,
261 		      const void *buf, unsigned len)
262 {
263 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
264 	struct fw_rsc_vdev *rsc;
265 	void *cfg;
266 
267 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
268 	cfg = &rsc->vring[rsc->num_of_vrings];
269 
270 	if (offset + len > rsc->config_len || offset + len < len) {
271 		dev_err(&vdev->dev, "rproc_virtio_set: access out of bounds\n");
272 		return;
273 	}
274 
275 	memcpy(cfg + offset, buf, len);
276 }
277 
278 static const struct virtio_config_ops rproc_virtio_config_ops = {
279 	.get_features	= rproc_virtio_get_features,
280 	.finalize_features = rproc_virtio_finalize_features,
281 	.find_vqs	= rproc_virtio_find_vqs,
282 	.del_vqs	= rproc_virtio_del_vqs,
283 	.reset		= rproc_virtio_reset,
284 	.set_status	= rproc_virtio_set_status,
285 	.get_status	= rproc_virtio_get_status,
286 	.get		= rproc_virtio_get,
287 	.set		= rproc_virtio_set,
288 };
289 
290 /*
291  * This function is called whenever vdev is released, and is responsible
292  * to decrement the remote processor's refcount which was taken when vdev was
293  * added.
294  *
295  * Never call this function directly; it will be called by the driver
296  * core when needed.
297  */
298 static void rproc_vdev_release(struct device *dev)
299 {
300 	struct virtio_device *vdev = dev_to_virtio(dev);
301 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
302 	struct rproc *rproc = vdev_to_rproc(vdev);
303 
304 	list_del(&rvdev->node);
305 	kfree(rvdev);
306 
307 	put_device(&rproc->dev);
308 }
309 
310 /**
311  * rproc_add_virtio_dev() - register an rproc-induced virtio device
312  * @rvdev: the remote vdev
313  *
314  * This function registers a virtio device. This vdev's partent is
315  * the rproc device.
316  *
317  * Returns 0 on success or an appropriate error value otherwise.
318  */
319 int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
320 {
321 	struct rproc *rproc = rvdev->rproc;
322 	struct device *dev = &rproc->dev;
323 	struct virtio_device *vdev = &rvdev->vdev;
324 	int ret;
325 
326 	vdev->id.device	= id,
327 	vdev->config = &rproc_virtio_config_ops,
328 	vdev->dev.parent = dev;
329 	vdev->dev.release = rproc_vdev_release;
330 
331 	/*
332 	 * We're indirectly making a non-temporary copy of the rproc pointer
333 	 * here, because drivers probed with this vdev will indirectly
334 	 * access the wrapping rproc.
335 	 *
336 	 * Therefore we must increment the rproc refcount here, and decrement
337 	 * it _only_ when the vdev is released.
338 	 */
339 	get_device(&rproc->dev);
340 
341 	ret = register_virtio_device(vdev);
342 	if (ret) {
343 		put_device(&rproc->dev);
344 		dev_err(dev, "failed to register vdev: %d\n", ret);
345 		goto out;
346 	}
347 
348 	dev_info(dev, "registered %s (type %d)\n", dev_name(&vdev->dev), id);
349 
350 out:
351 	return ret;
352 }
353 
354 /**
355  * rproc_remove_virtio_dev() - remove an rproc-induced virtio device
356  * @rvdev: the remote vdev
357  *
358  * This function unregisters an existing virtio device.
359  */
360 void rproc_remove_virtio_dev(struct rproc_vdev *rvdev)
361 {
362 	unregister_virtio_device(&rvdev->vdev);
363 }
364