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 int id,
73 				    void (*callback)(struct virtqueue *vq),
74 				    const char *name, bool ctx)
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_mem_entry *mem;
80 	struct rproc_vring *rvring;
81 	struct fw_rsc_vdev *rsc;
82 	struct virtqueue *vq;
83 	void *addr;
84 	int len, size;
85 
86 	/* we're temporarily limited to two virtqueues per rvdev */
87 	if (id >= ARRAY_SIZE(rvdev->vring))
88 		return ERR_PTR(-EINVAL);
89 
90 	if (!name)
91 		return NULL;
92 
93 	/* Search allocated memory region by name */
94 	mem = rproc_find_carveout_by_name(rproc, "vdev%dvring%d", rvdev->index,
95 					  id);
96 	if (!mem || !mem->va)
97 		return ERR_PTR(-ENOMEM);
98 
99 	rvring = &rvdev->vring[id];
100 	addr = mem->va;
101 	len = rvring->len;
102 
103 	/* zero vring */
104 	size = vring_size(len, rvring->align);
105 	memset(addr, 0, size);
106 
107 	dev_dbg(dev, "vring%d: va %pK qsz %d notifyid %d\n",
108 		id, addr, len, rvring->notifyid);
109 
110 	/*
111 	 * Create the new vq, and tell virtio we're not interested in
112 	 * the 'weak' smp barriers, since we're talking with a real device.
113 	 */
114 	vq = vring_new_virtqueue(id, len, rvring->align, vdev, false, ctx,
115 				 addr, rproc_virtio_notify, callback, name);
116 	if (!vq) {
117 		dev_err(dev, "vring_new_virtqueue %s failed\n", name);
118 		rproc_free_vring(rvring);
119 		return ERR_PTR(-ENOMEM);
120 	}
121 
122 	rvring->vq = vq;
123 	vq->priv = rvring;
124 
125 	/* Update vring in resource table */
126 	rsc = (void *)rproc->table_ptr + rvdev->rsc_offset;
127 	rsc->vring[id].da = mem->da;
128 
129 	return vq;
130 }
131 
132 static void __rproc_virtio_del_vqs(struct virtio_device *vdev)
133 {
134 	struct virtqueue *vq, *n;
135 	struct rproc_vring *rvring;
136 
137 	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
138 		rvring = vq->priv;
139 		rvring->vq = NULL;
140 		vring_del_virtqueue(vq);
141 	}
142 }
143 
144 static void rproc_virtio_del_vqs(struct virtio_device *vdev)
145 {
146 	__rproc_virtio_del_vqs(vdev);
147 }
148 
149 static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
150 				 struct virtqueue *vqs[],
151 				 vq_callback_t *callbacks[],
152 				 const char * const names[],
153 				 const bool * ctx,
154 				 struct irq_affinity *desc)
155 {
156 	int i, ret, queue_idx = 0;
157 
158 	for (i = 0; i < nvqs; ++i) {
159 		if (!names[i]) {
160 			vqs[i] = NULL;
161 			continue;
162 		}
163 
164 		vqs[i] = rp_find_vq(vdev, queue_idx++, callbacks[i], names[i],
165 				    ctx ? ctx[i] : false);
166 		if (IS_ERR(vqs[i])) {
167 			ret = PTR_ERR(vqs[i]);
168 			goto error;
169 		}
170 	}
171 
172 	return 0;
173 
174 error:
175 	__rproc_virtio_del_vqs(vdev);
176 	return ret;
177 }
178 
179 static u8 rproc_virtio_get_status(struct virtio_device *vdev)
180 {
181 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
182 	struct fw_rsc_vdev *rsc;
183 
184 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
185 
186 	return rsc->status;
187 }
188 
189 static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
190 {
191 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
192 	struct fw_rsc_vdev *rsc;
193 
194 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
195 
196 	rsc->status = status;
197 	dev_dbg(&vdev->dev, "status: %d\n", status);
198 }
199 
200 static void rproc_virtio_reset(struct virtio_device *vdev)
201 {
202 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
203 	struct fw_rsc_vdev *rsc;
204 
205 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
206 
207 	rsc->status = 0;
208 	dev_dbg(&vdev->dev, "reset !\n");
209 }
210 
211 /* provide the vdev features as retrieved from the firmware */
212 static u64 rproc_virtio_get_features(struct virtio_device *vdev)
213 {
214 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
215 	struct fw_rsc_vdev *rsc;
216 
217 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
218 
219 	return rsc->dfeatures;
220 }
221 
222 static void rproc_transport_features(struct virtio_device *vdev)
223 {
224 	/*
225 	 * Packed ring isn't enabled on remoteproc for now,
226 	 * because remoteproc uses vring_new_virtqueue() which
227 	 * creates virtio rings on preallocated memory.
228 	 */
229 	__virtio_clear_bit(vdev, VIRTIO_F_RING_PACKED);
230 }
231 
232 static int rproc_virtio_finalize_features(struct virtio_device *vdev)
233 {
234 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
235 	struct fw_rsc_vdev *rsc;
236 
237 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
238 
239 	/* Give virtio_ring a chance to accept features */
240 	vring_transport_features(vdev);
241 
242 	/* Give virtio_rproc a chance to accept features. */
243 	rproc_transport_features(vdev);
244 
245 	/* Make sure we don't have any features > 32 bits! */
246 	BUG_ON((u32)vdev->features != vdev->features);
247 
248 	/*
249 	 * Remember the finalized features of our vdev, and provide it
250 	 * to the remote processor once it is powered on.
251 	 */
252 	rsc->gfeatures = vdev->features;
253 
254 	return 0;
255 }
256 
257 static void rproc_virtio_get(struct virtio_device *vdev, unsigned int offset,
258 			     void *buf, unsigned int len)
259 {
260 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
261 	struct fw_rsc_vdev *rsc;
262 	void *cfg;
263 
264 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
265 	cfg = &rsc->vring[rsc->num_of_vrings];
266 
267 	if (offset + len > rsc->config_len || offset + len < len) {
268 		dev_err(&vdev->dev, "rproc_virtio_get: access out of bounds\n");
269 		return;
270 	}
271 
272 	memcpy(buf, cfg + offset, len);
273 }
274 
275 static void rproc_virtio_set(struct virtio_device *vdev, unsigned int offset,
276 			     const void *buf, unsigned int len)
277 {
278 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
279 	struct fw_rsc_vdev *rsc;
280 	void *cfg;
281 
282 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
283 	cfg = &rsc->vring[rsc->num_of_vrings];
284 
285 	if (offset + len > rsc->config_len || offset + len < len) {
286 		dev_err(&vdev->dev, "rproc_virtio_set: access out of bounds\n");
287 		return;
288 	}
289 
290 	memcpy(cfg + offset, buf, len);
291 }
292 
293 static const struct virtio_config_ops rproc_virtio_config_ops = {
294 	.get_features	= rproc_virtio_get_features,
295 	.finalize_features = rproc_virtio_finalize_features,
296 	.find_vqs	= rproc_virtio_find_vqs,
297 	.del_vqs	= rproc_virtio_del_vqs,
298 	.reset		= rproc_virtio_reset,
299 	.set_status	= rproc_virtio_set_status,
300 	.get_status	= rproc_virtio_get_status,
301 	.get		= rproc_virtio_get,
302 	.set		= rproc_virtio_set,
303 };
304 
305 /*
306  * This function is called whenever vdev is released, and is responsible
307  * to decrement the remote processor's refcount which was taken when vdev was
308  * added.
309  *
310  * Never call this function directly; it will be called by the driver
311  * core when needed.
312  */
313 static void rproc_virtio_dev_release(struct device *dev)
314 {
315 	struct virtio_device *vdev = dev_to_virtio(dev);
316 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
317 	struct rproc *rproc = vdev_to_rproc(vdev);
318 
319 	kref_put(&rvdev->refcount, rproc_vdev_release);
320 
321 	put_device(&rproc->dev);
322 }
323 
324 /**
325  * rproc_add_virtio_dev() - register an rproc-induced virtio device
326  * @rvdev: the remote vdev
327  *
328  * This function registers a virtio device. This vdev's partent is
329  * the rproc device.
330  *
331  * Returns 0 on success or an appropriate error value otherwise.
332  */
333 int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
334 {
335 	struct rproc *rproc = rvdev->rproc;
336 	struct device *dev = &rproc->dev;
337 	struct virtio_device *vdev = &rvdev->vdev;
338 	int ret;
339 
340 	vdev->id.device	= id,
341 	vdev->config = &rproc_virtio_config_ops,
342 	vdev->dev.parent = dev;
343 	vdev->dev.release = rproc_virtio_dev_release;
344 
345 	/*
346 	 * We're indirectly making a non-temporary copy of the rproc pointer
347 	 * here, because drivers probed with this vdev will indirectly
348 	 * access the wrapping rproc.
349 	 *
350 	 * Therefore we must increment the rproc refcount here, and decrement
351 	 * it _only_ when the vdev is released.
352 	 */
353 	get_device(&rproc->dev);
354 
355 	/* Reference the vdev and vring allocations */
356 	kref_get(&rvdev->refcount);
357 
358 	ret = register_virtio_device(vdev);
359 	if (ret) {
360 		put_device(&vdev->dev);
361 		dev_err(dev, "failed to register vdev: %d\n", ret);
362 		goto out;
363 	}
364 
365 	dev_info(dev, "registered %s (type %d)\n", dev_name(&vdev->dev), id);
366 
367 out:
368 	return ret;
369 }
370 
371 /**
372  * rproc_remove_virtio_dev() - remove an rproc-induced virtio device
373  * @rvdev: the remote vdev
374  *
375  * This function unregisters an existing virtio device.
376  */
377 void rproc_remove_virtio_dev(struct rproc_vdev *rvdev)
378 {
379 	unregister_virtio_device(&rvdev->vdev);
380 }
381