1// SPDX-License-Identifier: GPL-2.0 OR MIT
  2
  3/*
  4 *  Xen para-virtual DRM device
  5 *
  6 * Copyright (C) 2016-2018 EPAM Systems Inc.
  7 *
  8 * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
  9 */
 10
 11#include <linux/errno.h>
 12#include <linux/irq.h>
 13
 14#include <drm/drm_print.h>
 15
 16#include <xen/xenbus.h>
 17#include <xen/events.h>
 18#include <xen/grant_table.h>
 19
 20#include "xen_drm_front.h"
 21#include "xen_drm_front_evtchnl.h"
 22
 23static irqreturn_t evtchnl_interrupt_ctrl(int irq, void *dev_id)
 24{
 25	struct xen_drm_front_evtchnl *evtchnl = dev_id;
 26	struct xen_drm_front_info *front_info = evtchnl->front_info;
 27	struct xendispl_resp *resp;
 28	RING_IDX i, rp;
 29	unsigned long flags;
 30
 31	if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED))
 32		return IRQ_HANDLED;
 33
 34	spin_lock_irqsave(&front_info->io_lock, flags);
 35
 36again:
 37	rp = evtchnl->u.req.ring.sring->rsp_prod;
 38	/* ensure we see queued responses up to rp */
 39	virt_rmb();
 40
 41	for (i = evtchnl->u.req.ring.rsp_cons; i != rp; i++) {
 42		resp = RING_GET_RESPONSE(&evtchnl->u.req.ring, i);
 43		if (unlikely(resp->id != evtchnl->evt_id))
 44			continue;
 45
 46		switch (resp->operation) {
 47		case XENDISPL_OP_PG_FLIP:
 48		case XENDISPL_OP_FB_ATTACH:
 49		case XENDISPL_OP_FB_DETACH:
 50		case XENDISPL_OP_DBUF_CREATE:
 51		case XENDISPL_OP_DBUF_DESTROY:
 52		case XENDISPL_OP_SET_CONFIG:
 53			evtchnl->u.req.resp_status = resp->status;
 54			complete(&evtchnl->u.req.completion);
 55			break;
 56
 57		default:
 58			DRM_ERROR("Operation %d is not supported\n",
 59				  resp->operation);
 60			break;
 61		}
 62	}
 63
 64	evtchnl->u.req.ring.rsp_cons = i;
 65
 66	if (i != evtchnl->u.req.ring.req_prod_pvt) {
 67		int more_to_do;
 68
 69		RING_FINAL_CHECK_FOR_RESPONSES(&evtchnl->u.req.ring,
 70					       more_to_do);
 71		if (more_to_do)
 72			goto again;
 73	} else {
 74		evtchnl->u.req.ring.sring->rsp_event = i + 1;
 75	}
 76
 77	spin_unlock_irqrestore(&front_info->io_lock, flags);
 78	return IRQ_HANDLED;
 79}
 80
 81static irqreturn_t evtchnl_interrupt_evt(int irq, void *dev_id)
 82{
 83	struct xen_drm_front_evtchnl *evtchnl = dev_id;
 84	struct xen_drm_front_info *front_info = evtchnl->front_info;
 85	struct xendispl_event_page *page = evtchnl->u.evt.page;
 86	u32 cons, prod;
 87	unsigned long flags;
 88
 89	if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED))
 90		return IRQ_HANDLED;
 91
 92	spin_lock_irqsave(&front_info->io_lock, flags);
 93
 94	prod = page->in_prod;
 95	/* ensure we see ring contents up to prod */
 96	virt_rmb();
 97	if (prod == page->in_cons)
 98		goto out;
 99
100	for (cons = page->in_cons; cons != prod; cons++) {
101		struct xendispl_evt *event;
102
103		event = &XENDISPL_IN_RING_REF(page, cons);
104		if (unlikely(event->id != evtchnl->evt_id++))
105			continue;
106
107		switch (event->type) {
108		case XENDISPL_EVT_PG_FLIP:
109			xen_drm_front_on_frame_done(front_info, evtchnl->index,
110						    event->op.pg_flip.fb_cookie);
111			break;
112		}
113	}
114	page->in_cons = cons;
115	/* ensure ring contents */
116	virt_wmb();
117
118out:
119	spin_unlock_irqrestore(&front_info->io_lock, flags);
120	return IRQ_HANDLED;
121}
122
123static void evtchnl_free(struct xen_drm_front_info *front_info,
124			 struct xen_drm_front_evtchnl *evtchnl)
125{
126	unsigned long page = 0;
127
128	if (evtchnl->type == EVTCHNL_TYPE_REQ)
129		page = (unsigned long)evtchnl->u.req.ring.sring;
130	else if (evtchnl->type == EVTCHNL_TYPE_EVT)
131		page = (unsigned long)evtchnl->u.evt.page;
132	if (!page)
133		return;
134
135	evtchnl->state = EVTCHNL_STATE_DISCONNECTED;
136
137	if (evtchnl->type == EVTCHNL_TYPE_REQ) {
138		/* release all who still waits for response if any */
139		evtchnl->u.req.resp_status = -EIO;
140		complete_all(&evtchnl->u.req.completion);
141	}
142
143	if (evtchnl->irq)
144		unbind_from_irqhandler(evtchnl->irq, evtchnl);
145
146	if (evtchnl->port)
147		xenbus_free_evtchn(front_info->xb_dev, evtchnl->port);
148
149	/* end access and free the page */
150	if (evtchnl->gref != GRANT_INVALID_REF)
151		gnttab_end_foreign_access(evtchnl->gref, 0, page);
152
153	memset(evtchnl, 0, sizeof(*evtchnl));
154}
155
156static int evtchnl_alloc(struct xen_drm_front_info *front_info, int index,
157			 struct xen_drm_front_evtchnl *evtchnl,
158			 enum xen_drm_front_evtchnl_type type)
159{
160	struct xenbus_device *xb_dev = front_info->xb_dev;
161	unsigned long page;
162	grant_ref_t gref;
163	irq_handler_t handler;
164	int ret;
165
166	memset(evtchnl, 0, sizeof(*evtchnl));
167	evtchnl->type = type;
168	evtchnl->index = index;
169	evtchnl->front_info = front_info;
170	evtchnl->state = EVTCHNL_STATE_DISCONNECTED;
171	evtchnl->gref = GRANT_INVALID_REF;
172
173	page = get_zeroed_page(GFP_NOIO | __GFP_HIGH);
174	if (!page) {
175		ret = -ENOMEM;
176		goto fail;
177	}
178
179	if (type == EVTCHNL_TYPE_REQ) {
180		struct xen_displif_sring *sring;
181
182		init_completion(&evtchnl->u.req.completion);
183		mutex_init(&evtchnl->u.req.req_io_lock);
184		sring = (struct xen_displif_sring *)page;
185		SHARED_RING_INIT(sring);
186		FRONT_RING_INIT(&evtchnl->u.req.ring, sring, XEN_PAGE_SIZE);
187
188		ret = xenbus_grant_ring(xb_dev, sring, 1, &gref);
189		if (ret < 0) {
190			evtchnl->u.req.ring.sring = NULL;
191			free_page(page);
192			goto fail;
193		}
194
195		handler = evtchnl_interrupt_ctrl;
196	} else {
197		ret = gnttab_grant_foreign_access(xb_dev->otherend_id,
198						  virt_to_gfn((void *)page), 0);
199		if (ret < 0) {
200			free_page(page);
201			goto fail;
202		}
203
204		evtchnl->u.evt.page = (struct xendispl_event_page *)page;
205		gref = ret;
206		handler = evtchnl_interrupt_evt;
207	}
208	evtchnl->gref = gref;
209
210	ret = xenbus_alloc_evtchn(xb_dev, &evtchnl->port);
211	if (ret < 0)
212		goto fail;
213
214	ret = bind_evtchn_to_irqhandler(evtchnl->port,
215					handler, 0, xb_dev->devicetype,
216					evtchnl);
217	if (ret < 0)
218		goto fail;
219
220	evtchnl->irq = ret;
221	return 0;
222
223fail:
224	DRM_ERROR("Failed to allocate ring: %d\n", ret);
225	return ret;
226}
227
228int xen_drm_front_evtchnl_create_all(struct xen_drm_front_info *front_info)
229{
230	struct xen_drm_front_cfg *cfg;
231	int ret, conn;
232
233	cfg = &front_info->cfg;
234
235	front_info->evt_pairs =
236			kcalloc(cfg->num_connectors,
237				sizeof(struct xen_drm_front_evtchnl_pair),
238				GFP_KERNEL);
239	if (!front_info->evt_pairs) {
240		ret = -ENOMEM;
241		goto fail;
242	}
243
244	for (conn = 0; conn < cfg->num_connectors; conn++) {
245		ret = evtchnl_alloc(front_info, conn,
246				    &front_info->evt_pairs[conn].req,
247				    EVTCHNL_TYPE_REQ);
248		if (ret < 0) {
249			DRM_ERROR("Error allocating control channel\n");
250			goto fail;
251		}
252
253		ret = evtchnl_alloc(front_info, conn,
254				    &front_info->evt_pairs[conn].evt,
255				    EVTCHNL_TYPE_EVT);
256		if (ret < 0) {
257			DRM_ERROR("Error allocating in-event channel\n");
258			goto fail;
259		}
260	}
261	front_info->num_evt_pairs = cfg->num_connectors;
262	return 0;
263
264fail:
265	xen_drm_front_evtchnl_free_all(front_info);
266	return ret;
267}
268
269static int evtchnl_publish(struct xenbus_transaction xbt,
270			   struct xen_drm_front_evtchnl *evtchnl,
271			   const char *path, const char *node_ring,
272			   const char *node_chnl)
273{
274	struct xenbus_device *xb_dev = evtchnl->front_info->xb_dev;
275	int ret;
276
277	/* write control channel ring reference */
278	ret = xenbus_printf(xbt, path, node_ring, "%u", evtchnl->gref);
279	if (ret < 0) {
280		xenbus_dev_error(xb_dev, ret, "writing ring-ref");
281		return ret;
282	}
283
284	/* write event channel ring reference */
285	ret = xenbus_printf(xbt, path, node_chnl, "%u", evtchnl->port);
286	if (ret < 0) {
287		xenbus_dev_error(xb_dev, ret, "writing event channel");
288		return ret;
289	}
290
291	return 0;
292}
293
294int xen_drm_front_evtchnl_publish_all(struct xen_drm_front_info *front_info)
295{
296	struct xenbus_transaction xbt;
297	struct xen_drm_front_cfg *plat_data;
298	int ret, conn;
299
300	plat_data = &front_info->cfg;
301
302again:
303	ret = xenbus_transaction_start(&xbt);
304	if (ret < 0) {
305		xenbus_dev_fatal(front_info->xb_dev, ret,
306				 "starting transaction");
307		return ret;
308	}
309
310	for (conn = 0; conn < plat_data->num_connectors; conn++) {
311		ret = evtchnl_publish(xbt, &front_info->evt_pairs[conn].req,
312				      plat_data->connectors[conn].xenstore_path,
313				      XENDISPL_FIELD_REQ_RING_REF,
314				      XENDISPL_FIELD_REQ_CHANNEL);
315		if (ret < 0)
316			goto fail;
317
318		ret = evtchnl_publish(xbt, &front_info->evt_pairs[conn].evt,
319				      plat_data->connectors[conn].xenstore_path,
320				      XENDISPL_FIELD_EVT_RING_REF,
321				      XENDISPL_FIELD_EVT_CHANNEL);
322		if (ret < 0)
323			goto fail;
324	}
325
326	ret = xenbus_transaction_end(xbt, 0);
327	if (ret < 0) {
328		if (ret == -EAGAIN)
329			goto again;
330
331		xenbus_dev_fatal(front_info->xb_dev, ret,
332				 "completing transaction");
333		goto fail_to_end;
334	}
335
336	return 0;
337
338fail:
339	xenbus_transaction_end(xbt, 1);
340
341fail_to_end:
342	xenbus_dev_fatal(front_info->xb_dev, ret, "writing Xen store");
343	return ret;
344}
345
346void xen_drm_front_evtchnl_flush(struct xen_drm_front_evtchnl *evtchnl)
347{
348	int notify;
349
350	evtchnl->u.req.ring.req_prod_pvt++;
351	RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&evtchnl->u.req.ring, notify);
352	if (notify)
353		notify_remote_via_irq(evtchnl->irq);
354}
355
356void xen_drm_front_evtchnl_set_state(struct xen_drm_front_info *front_info,
357				     enum xen_drm_front_evtchnl_state state)
358{
359	unsigned long flags;
360	int i;
361
362	if (!front_info->evt_pairs)
363		return;
364
365	spin_lock_irqsave(&front_info->io_lock, flags);
366	for (i = 0; i < front_info->num_evt_pairs; i++) {
367		front_info->evt_pairs[i].req.state = state;
368		front_info->evt_pairs[i].evt.state = state;
369	}
370	spin_unlock_irqrestore(&front_info->io_lock, flags);
371}
372
373void xen_drm_front_evtchnl_free_all(struct xen_drm_front_info *front_info)
374{
375	int i;
376
377	if (!front_info->evt_pairs)
378		return;
379
380	for (i = 0; i < front_info->num_evt_pairs; i++) {
381		evtchnl_free(front_info, &front_info->evt_pairs[i].req);
382		evtchnl_free(front_info, &front_info->evt_pairs[i].evt);
383	}
384
385	kfree(front_info->evt_pairs);
386	front_info->evt_pairs = NULL;
387}