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)
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;
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 	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(id, 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 
120 static void __rproc_virtio_del_vqs(struct virtio_device *vdev)
121 {
122 	struct virtqueue *vq, *n;
123 	struct rproc_vring *rvring;
124 
125 	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
126 		rvring = vq->priv;
127 		rvring->vq = NULL;
128 		vring_del_virtqueue(vq);
129 	}
130 }
131 
132 static void rproc_virtio_del_vqs(struct virtio_device *vdev)
133 {
134 	__rproc_virtio_del_vqs(vdev);
135 }
136 
137 static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
138 				 struct virtqueue *vqs[],
139 				 vq_callback_t *callbacks[],
140 				 const char * const names[])
141 {
142 	int i, ret;
143 
144 	for (i = 0; i < nvqs; ++i) {
145 		vqs[i] = rp_find_vq(vdev, i, callbacks[i], names[i]);
146 		if (IS_ERR(vqs[i])) {
147 			ret = PTR_ERR(vqs[i]);
148 			goto error;
149 		}
150 	}
151 
152 	return 0;
153 
154 error:
155 	__rproc_virtio_del_vqs(vdev);
156 	return ret;
157 }
158 
159 static u8 rproc_virtio_get_status(struct virtio_device *vdev)
160 {
161 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
162 	struct fw_rsc_vdev *rsc;
163 
164 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
165 
166 	return rsc->status;
167 }
168 
169 static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
170 {
171 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
172 	struct fw_rsc_vdev *rsc;
173 
174 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
175 
176 	rsc->status = status;
177 	dev_dbg(&vdev->dev, "status: %d\n", status);
178 }
179 
180 static void rproc_virtio_reset(struct virtio_device *vdev)
181 {
182 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
183 	struct fw_rsc_vdev *rsc;
184 
185 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
186 
187 	rsc->status = 0;
188 	dev_dbg(&vdev->dev, "reset !\n");
189 }
190 
191 /* provide the vdev features as retrieved from the firmware */
192 static u64 rproc_virtio_get_features(struct virtio_device *vdev)
193 {
194 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
195 	struct fw_rsc_vdev *rsc;
196 
197 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
198 
199 	return rsc->dfeatures;
200 }
201 
202 static int rproc_virtio_finalize_features(struct virtio_device *vdev)
203 {
204 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
205 	struct fw_rsc_vdev *rsc;
206 
207 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
208 
209 	/* Give virtio_ring a chance to accept features */
210 	vring_transport_features(vdev);
211 
212 	/* Make sure we don't have any features > 32 bits! */
213 	BUG_ON((u32)vdev->features != vdev->features);
214 
215 	/*
216 	 * Remember the finalized features of our vdev, and provide it
217 	 * to the remote processor once it is powered on.
218 	 */
219 	rsc->gfeatures = vdev->features;
220 
221 	return 0;
222 }
223 
224 static void rproc_virtio_get(struct virtio_device *vdev, unsigned int offset,
225 			     void *buf, unsigned int len)
226 {
227 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
228 	struct fw_rsc_vdev *rsc;
229 	void *cfg;
230 
231 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
232 	cfg = &rsc->vring[rsc->num_of_vrings];
233 
234 	if (offset + len > rsc->config_len || offset + len < len) {
235 		dev_err(&vdev->dev, "rproc_virtio_get: access out of bounds\n");
236 		return;
237 	}
238 
239 	memcpy(buf, cfg + offset, len);
240 }
241 
242 static void rproc_virtio_set(struct virtio_device *vdev, unsigned int offset,
243 			     const void *buf, unsigned int 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_set: access out of bounds\n");
254 		return;
255 	}
256 
257 	memcpy(cfg + offset, buf, len);
258 }
259 
260 static const struct virtio_config_ops rproc_virtio_config_ops = {
261 	.get_features	= rproc_virtio_get_features,
262 	.finalize_features = rproc_virtio_finalize_features,
263 	.find_vqs	= rproc_virtio_find_vqs,
264 	.del_vqs	= rproc_virtio_del_vqs,
265 	.reset		= rproc_virtio_reset,
266 	.set_status	= rproc_virtio_set_status,
267 	.get_status	= rproc_virtio_get_status,
268 	.get		= rproc_virtio_get,
269 	.set		= rproc_virtio_set,
270 };
271 
272 /*
273  * This function is called whenever vdev is released, and is responsible
274  * to decrement the remote processor's refcount which was taken when vdev was
275  * added.
276  *
277  * Never call this function directly; it will be called by the driver
278  * core when needed.
279  */
280 static void rproc_virtio_dev_release(struct device *dev)
281 {
282 	struct virtio_device *vdev = dev_to_virtio(dev);
283 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
284 	struct rproc *rproc = vdev_to_rproc(vdev);
285 
286 	kref_put(&rvdev->refcount, rproc_vdev_release);
287 
288 	put_device(&rproc->dev);
289 }
290 
291 /**
292  * rproc_add_virtio_dev() - register an rproc-induced virtio device
293  * @rvdev: the remote vdev
294  *
295  * This function registers a virtio device. This vdev's partent is
296  * the rproc device.
297  *
298  * Returns 0 on success or an appropriate error value otherwise.
299  */
300 int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
301 {
302 	struct rproc *rproc = rvdev->rproc;
303 	struct device *dev = &rproc->dev;
304 	struct virtio_device *vdev = &rvdev->vdev;
305 	int ret;
306 
307 	vdev->id.device	= id,
308 	vdev->config = &rproc_virtio_config_ops,
309 	vdev->dev.parent = dev;
310 	vdev->dev.release = rproc_virtio_dev_release;
311 
312 	/*
313 	 * We're indirectly making a non-temporary copy of the rproc pointer
314 	 * here, because drivers probed with this vdev will indirectly
315 	 * access the wrapping rproc.
316 	 *
317 	 * Therefore we must increment the rproc refcount here, and decrement
318 	 * it _only_ when the vdev is released.
319 	 */
320 	get_device(&rproc->dev);
321 
322 	/* Reference the vdev and vring allocations */
323 	kref_get(&rvdev->refcount);
324 
325 	ret = register_virtio_device(vdev);
326 	if (ret) {
327 		put_device(&rproc->dev);
328 		dev_err(dev, "failed to register vdev: %d\n", ret);
329 		goto out;
330 	}
331 
332 	dev_info(dev, "registered %s (type %d)\n", dev_name(&vdev->dev), id);
333 
334 out:
335 	return ret;
336 }
337 
338 /**
339  * rproc_remove_virtio_dev() - remove an rproc-induced virtio device
340  * @rvdev: the remote vdev
341  *
342  * This function unregisters an existing virtio device.
343  */
344 void rproc_remove_virtio_dev(struct rproc_vdev *rvdev)
345 {
346 	unregister_virtio_device(&rvdev->vdev);
347 }
348