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_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, ctx,
107 				 addr, 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 				 const bool * ctx,
142 				 struct irq_affinity *desc)
143 {
144 	int i, ret;
145 
146 	for (i = 0; i < nvqs; ++i) {
147 		vqs[i] = rp_find_vq(vdev, i, callbacks[i], names[i],
148 				    ctx ? ctx[i] : false);
149 		if (IS_ERR(vqs[i])) {
150 			ret = PTR_ERR(vqs[i]);
151 			goto error;
152 		}
153 	}
154 
155 	return 0;
156 
157 error:
158 	__rproc_virtio_del_vqs(vdev);
159 	return ret;
160 }
161 
162 static u8 rproc_virtio_get_status(struct virtio_device *vdev)
163 {
164 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
165 	struct fw_rsc_vdev *rsc;
166 
167 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
168 
169 	return rsc->status;
170 }
171 
172 static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
173 {
174 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
175 	struct fw_rsc_vdev *rsc;
176 
177 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
178 
179 	rsc->status = status;
180 	dev_dbg(&vdev->dev, "status: %d\n", status);
181 }
182 
183 static void rproc_virtio_reset(struct virtio_device *vdev)
184 {
185 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
186 	struct fw_rsc_vdev *rsc;
187 
188 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
189 
190 	rsc->status = 0;
191 	dev_dbg(&vdev->dev, "reset !\n");
192 }
193 
194 /* provide the vdev features as retrieved from the firmware */
195 static u64 rproc_virtio_get_features(struct virtio_device *vdev)
196 {
197 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
198 	struct fw_rsc_vdev *rsc;
199 
200 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
201 
202 	return rsc->dfeatures;
203 }
204 
205 static int rproc_virtio_finalize_features(struct virtio_device *vdev)
206 {
207 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
208 	struct fw_rsc_vdev *rsc;
209 
210 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
211 
212 	/* Give virtio_ring a chance to accept features */
213 	vring_transport_features(vdev);
214 
215 	/* Make sure we don't have any features > 32 bits! */
216 	BUG_ON((u32)vdev->features != vdev->features);
217 
218 	/*
219 	 * Remember the finalized features of our vdev, and provide it
220 	 * to the remote processor once it is powered on.
221 	 */
222 	rsc->gfeatures = vdev->features;
223 
224 	return 0;
225 }
226 
227 static void rproc_virtio_get(struct virtio_device *vdev, unsigned int offset,
228 			     void *buf, unsigned int len)
229 {
230 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
231 	struct fw_rsc_vdev *rsc;
232 	void *cfg;
233 
234 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
235 	cfg = &rsc->vring[rsc->num_of_vrings];
236 
237 	if (offset + len > rsc->config_len || offset + len < len) {
238 		dev_err(&vdev->dev, "rproc_virtio_get: access out of bounds\n");
239 		return;
240 	}
241 
242 	memcpy(buf, cfg + offset, len);
243 }
244 
245 static void rproc_virtio_set(struct virtio_device *vdev, unsigned int offset,
246 			     const void *buf, unsigned int len)
247 {
248 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
249 	struct fw_rsc_vdev *rsc;
250 	void *cfg;
251 
252 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
253 	cfg = &rsc->vring[rsc->num_of_vrings];
254 
255 	if (offset + len > rsc->config_len || offset + len < len) {
256 		dev_err(&vdev->dev, "rproc_virtio_set: access out of bounds\n");
257 		return;
258 	}
259 
260 	memcpy(cfg + offset, buf, len);
261 }
262 
263 static const struct virtio_config_ops rproc_virtio_config_ops = {
264 	.get_features	= rproc_virtio_get_features,
265 	.finalize_features = rproc_virtio_finalize_features,
266 	.find_vqs	= rproc_virtio_find_vqs,
267 	.del_vqs	= rproc_virtio_del_vqs,
268 	.reset		= rproc_virtio_reset,
269 	.set_status	= rproc_virtio_set_status,
270 	.get_status	= rproc_virtio_get_status,
271 	.get		= rproc_virtio_get,
272 	.set		= rproc_virtio_set,
273 };
274 
275 /*
276  * This function is called whenever vdev is released, and is responsible
277  * to decrement the remote processor's refcount which was taken when vdev was
278  * added.
279  *
280  * Never call this function directly; it will be called by the driver
281  * core when needed.
282  */
283 static void rproc_virtio_dev_release(struct device *dev)
284 {
285 	struct virtio_device *vdev = dev_to_virtio(dev);
286 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
287 	struct rproc *rproc = vdev_to_rproc(vdev);
288 
289 	kref_put(&rvdev->refcount, rproc_vdev_release);
290 
291 	put_device(&rproc->dev);
292 }
293 
294 /**
295  * rproc_add_virtio_dev() - register an rproc-induced virtio device
296  * @rvdev: the remote vdev
297  *
298  * This function registers a virtio device. This vdev's partent is
299  * the rproc device.
300  *
301  * Returns 0 on success or an appropriate error value otherwise.
302  */
303 int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
304 {
305 	struct rproc *rproc = rvdev->rproc;
306 	struct device *dev = &rproc->dev;
307 	struct virtio_device *vdev = &rvdev->vdev;
308 	int ret;
309 
310 	vdev->id.device	= id,
311 	vdev->config = &rproc_virtio_config_ops,
312 	vdev->dev.parent = dev;
313 	vdev->dev.release = rproc_virtio_dev_release;
314 
315 	/*
316 	 * We're indirectly making a non-temporary copy of the rproc pointer
317 	 * here, because drivers probed with this vdev will indirectly
318 	 * access the wrapping rproc.
319 	 *
320 	 * Therefore we must increment the rproc refcount here, and decrement
321 	 * it _only_ when the vdev is released.
322 	 */
323 	get_device(&rproc->dev);
324 
325 	/* Reference the vdev and vring allocations */
326 	kref_get(&rvdev->refcount);
327 
328 	ret = register_virtio_device(vdev);
329 	if (ret) {
330 		put_device(&rproc->dev);
331 		dev_err(dev, "failed to register vdev: %d\n", ret);
332 		goto out;
333 	}
334 
335 	dev_info(dev, "registered %s (type %d)\n", dev_name(&vdev->dev), id);
336 
337 out:
338 	return ret;
339 }
340 
341 /**
342  * rproc_remove_virtio_dev() - remove an rproc-induced virtio device
343  * @rvdev: the remote vdev
344  *
345  * This function unregisters an existing virtio device.
346  */
347 void rproc_remove_virtio_dev(struct rproc_vdev *rvdev)
348 {
349 	unregister_virtio_device(&rvdev->vdev);
350 }
351