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 */
 33static 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 */
 56irqreturn_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}
 68EXPORT_SYMBOL(rproc_vq_interrupt);
 69
 70static 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 rproc_vring *rvring;
 78	struct virtqueue *vq;
 79	void *addr;
 80	int len, size;
 81
 82	/* we're temporarily limited to two virtqueues per rvdev */
 83	if (id >= ARRAY_SIZE(rvdev->vring))
 84		return ERR_PTR(-EINVAL);
 85
 86	rvring = &rvdev->vring[id];
 87
 88	addr = rvring->va;
 89	len = rvring->len;
 90
 91	/* zero vring */
 92	size = vring_size(len, rvring->align);
 93	memset(addr, 0, size);
 94
 95	dev_dbg(rproc->dev, "vring%d: va %p qsz %d notifyid %d\n",
 96					id, addr, len, rvring->notifyid);
 97
 98	/*
 99	 * Create the new vq, and tell virtio we're not interested in
100	 * the 'weak' smp barriers, since we're talking with a real device.
101	 */
102	vq = vring_new_virtqueue(len, rvring->align, vdev, false, addr,
103					rproc_virtio_notify, callback, name);
104	if (!vq) {
105		dev_err(rproc->dev, "vring_new_virtqueue %s failed\n", name);
106		return ERR_PTR(-ENOMEM);
107	}
108
109	rvring->vq = vq;
110	vq->priv = rvring;
111
112	return vq;
113}
114
115static void rproc_virtio_del_vqs(struct virtio_device *vdev)
116{
117	struct virtqueue *vq, *n;
118	struct rproc *rproc = vdev_to_rproc(vdev);
119	struct rproc_vring *rvring;
120
121	/* power down the remote processor before deleting vqs */
122	rproc_shutdown(rproc);
123
124	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
125		rvring = vq->priv;
126		rvring->vq = NULL;
127		vring_del_virtqueue(vq);
128	}
129}
130
131static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
132		       struct virtqueue *vqs[],
133		       vq_callback_t *callbacks[],
134		       const char *names[])
135{
136	struct rproc *rproc = vdev_to_rproc(vdev);
137	int i, ret;
138
139	for (i = 0; i < nvqs; ++i) {
140		vqs[i] = rp_find_vq(vdev, i, callbacks[i], names[i]);
141		if (IS_ERR(vqs[i])) {
142			ret = PTR_ERR(vqs[i]);
143			goto error;
144		}
145	}
146
147	/* now that the vqs are all set, boot the remote processor */
148	ret = rproc_boot(rproc);
149	if (ret) {
150		dev_err(rproc->dev, "rproc_boot() failed %d\n", ret);
151		goto error;
152	}
153
154	return 0;
155
156error:
157	rproc_virtio_del_vqs(vdev);
158	return ret;
159}
160
161/*
162 * We don't support yet real virtio status semantics.
163 *
164 * The plan is to provide this via the VDEV resource entry
165 * which is part of the firmware: this way the remote processor
166 * will be able to access the status values as set by us.
167 */
168static u8 rproc_virtio_get_status(struct virtio_device *vdev)
169{
170	return 0;
171}
172
173static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
174{
175	dev_dbg(&vdev->dev, "status: %d\n", status);
176}
177
178static void rproc_virtio_reset(struct virtio_device *vdev)
179{
180	dev_dbg(&vdev->dev, "reset !\n");
181}
182
183/* provide the vdev features as retrieved from the firmware */
184static u32 rproc_virtio_get_features(struct virtio_device *vdev)
185{
186	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
187
188	return rvdev->dfeatures;
189}
190
191static void rproc_virtio_finalize_features(struct virtio_device *vdev)
192{
193	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
194
195	/* Give virtio_ring a chance to accept features */
196	vring_transport_features(vdev);
197
198	/*
199	 * Remember the finalized features of our vdev, and provide it
200	 * to the remote processor once it is powered on.
201	 *
202	 * Similarly to the status field, we don't expose yet the negotiated
203	 * features to the remote processors at this point. This will be
204	 * fixed as part of a small resource table overhaul and then an
205	 * extension of the virtio resource entries.
206	 */
207	rvdev->gfeatures = vdev->features[0];
208}
209
210static struct virtio_config_ops rproc_virtio_config_ops = {
211	.get_features	= rproc_virtio_get_features,
212	.finalize_features = rproc_virtio_finalize_features,
213	.find_vqs	= rproc_virtio_find_vqs,
214	.del_vqs	= rproc_virtio_del_vqs,
215	.reset		= rproc_virtio_reset,
216	.set_status	= rproc_virtio_set_status,
217	.get_status	= rproc_virtio_get_status,
218};
219
220/*
221 * This function is called whenever vdev is released, and is responsible
222 * to decrement the remote processor's refcount taken when vdev was
223 * added.
224 *
225 * Never call this function directly; it will be called by the driver
226 * core when needed.
227 */
228static void rproc_vdev_release(struct device *dev)
229{
230	struct virtio_device *vdev = dev_to_virtio(dev);
231	struct rproc *rproc = vdev_to_rproc(vdev);
232
233	kref_put(&rproc->refcount, rproc_release);
234}
235
236/**
237 * rproc_add_virtio_dev() - register an rproc-induced virtio device
238 * @rvdev: the remote vdev
239 *
240 * This function registers a virtio device. This vdev's partent is
241 * the rproc device.
242 *
243 * Returns 0 on success or an appropriate error value otherwise.
244 */
245int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
246{
247	struct rproc *rproc = rvdev->rproc;
248	struct device *dev = rproc->dev;
249	struct virtio_device *vdev = &rvdev->vdev;
250	int ret;
251
252	vdev->id.device	= id,
253	vdev->config = &rproc_virtio_config_ops,
254	vdev->dev.parent = dev;
255	vdev->dev.release = rproc_vdev_release;
256
257	/*
258	 * We're indirectly making a non-temporary copy of the rproc pointer
259	 * here, because drivers probed with this vdev will indirectly
260	 * access the wrapping rproc.
261	 *
262	 * Therefore we must increment the rproc refcount here, and decrement
263	 * it _only_ when the vdev is released.
264	 */
265	kref_get(&rproc->refcount);
266
267	ret = register_virtio_device(vdev);
268	if (ret) {
269		kref_put(&rproc->refcount, rproc_release);
270		dev_err(dev, "failed to register vdev: %d\n", ret);
271		goto out;
272	}
273
274	dev_info(dev, "registered %s (type %d)\n", dev_name(&vdev->dev), id);
275
276out:
277	return ret;
278}
279
280/**
281 * rproc_remove_virtio_dev() - remove an rproc-induced virtio device
282 * @rvdev: the remote vdev
283 *
284 * This function unregisters an existing virtio device.
285 */
286void rproc_remove_virtio_dev(struct rproc_vdev *rvdev)
287{
288	unregister_virtio_device(&rvdev->vdev);
289}