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	void *page = NULL;
127
128	if (evtchnl->type == EVTCHNL_TYPE_REQ)
129		page = evtchnl->u.req.ring.sring;
130	else if (evtchnl->type == EVTCHNL_TYPE_EVT)
131		page = 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	xenbus_teardown_ring(&page, 1, &evtchnl->gref);
151
152	memset(evtchnl, 0, sizeof(*evtchnl));
153}
154
155static int evtchnl_alloc(struct xen_drm_front_info *front_info, int index,
156			 struct xen_drm_front_evtchnl *evtchnl,
157			 enum xen_drm_front_evtchnl_type type)
158{
159	struct xenbus_device *xb_dev = front_info->xb_dev;
160	void *page;
161	irq_handler_t handler;
162	int ret;
163
164	memset(evtchnl, 0, sizeof(*evtchnl));
165	evtchnl->type = type;
166	evtchnl->index = index;
167	evtchnl->front_info = front_info;
168	evtchnl->state = EVTCHNL_STATE_DISCONNECTED;
169
170	ret = xenbus_setup_ring(xb_dev, GFP_NOIO | __GFP_HIGH, &page,
171				1, &evtchnl->gref);
172	if (ret)
173		goto fail;
174
175	if (type == EVTCHNL_TYPE_REQ) {
176		struct xen_displif_sring *sring;
177
178		init_completion(&evtchnl->u.req.completion);
179		mutex_init(&evtchnl->u.req.req_io_lock);
180		sring = page;
181		XEN_FRONT_RING_INIT(&evtchnl->u.req.ring, sring, XEN_PAGE_SIZE);
182
183		handler = evtchnl_interrupt_ctrl;
184	} else {
185		evtchnl->u.evt.page = page;
186		handler = evtchnl_interrupt_evt;
187	}
188
189	ret = xenbus_alloc_evtchn(xb_dev, &evtchnl->port);
190	if (ret < 0)
191		goto fail;
192
193	ret = bind_evtchn_to_irqhandler(evtchnl->port,
194					handler, 0, xb_dev->devicetype,
195					evtchnl);
196	if (ret < 0)
197		goto fail;
198
199	evtchnl->irq = ret;
200	return 0;
201
202fail:
203	DRM_ERROR("Failed to allocate ring: %d\n", ret);
204	return ret;
205}
206
207int xen_drm_front_evtchnl_create_all(struct xen_drm_front_info *front_info)
208{
209	struct xen_drm_front_cfg *cfg;
210	int ret, conn;
211
212	cfg = &front_info->cfg;
213
214	front_info->evt_pairs =
215			kcalloc(cfg->num_connectors,
216				sizeof(struct xen_drm_front_evtchnl_pair),
217				GFP_KERNEL);
218	if (!front_info->evt_pairs) {
219		ret = -ENOMEM;
220		goto fail;
221	}
222
223	for (conn = 0; conn < cfg->num_connectors; conn++) {
224		ret = evtchnl_alloc(front_info, conn,
225				    &front_info->evt_pairs[conn].req,
226				    EVTCHNL_TYPE_REQ);
227		if (ret < 0) {
228			DRM_ERROR("Error allocating control channel\n");
229			goto fail;
230		}
231
232		ret = evtchnl_alloc(front_info, conn,
233				    &front_info->evt_pairs[conn].evt,
234				    EVTCHNL_TYPE_EVT);
235		if (ret < 0) {
236			DRM_ERROR("Error allocating in-event channel\n");
237			goto fail;
238		}
239	}
240	front_info->num_evt_pairs = cfg->num_connectors;
241	return 0;
242
243fail:
244	xen_drm_front_evtchnl_free_all(front_info);
245	return ret;
246}
247
248static int evtchnl_publish(struct xenbus_transaction xbt,
249			   struct xen_drm_front_evtchnl *evtchnl,
250			   const char *path, const char *node_ring,
251			   const char *node_chnl)
252{
253	struct xenbus_device *xb_dev = evtchnl->front_info->xb_dev;
254	int ret;
255
256	/* write control channel ring reference */
257	ret = xenbus_printf(xbt, path, node_ring, "%u", evtchnl->gref);
258	if (ret < 0) {
259		xenbus_dev_error(xb_dev, ret, "writing ring-ref");
260		return ret;
261	}
262
263	/* write event channel ring reference */
264	ret = xenbus_printf(xbt, path, node_chnl, "%u", evtchnl->port);
265	if (ret < 0) {
266		xenbus_dev_error(xb_dev, ret, "writing event channel");
267		return ret;
268	}
269
270	return 0;
271}
272
273int xen_drm_front_evtchnl_publish_all(struct xen_drm_front_info *front_info)
274{
275	struct xenbus_transaction xbt;
276	struct xen_drm_front_cfg *plat_data;
277	int ret, conn;
278
279	plat_data = &front_info->cfg;
280
281again:
282	ret = xenbus_transaction_start(&xbt);
283	if (ret < 0) {
284		xenbus_dev_fatal(front_info->xb_dev, ret,
285				 "starting transaction");
286		return ret;
287	}
288
289	for (conn = 0; conn < plat_data->num_connectors; conn++) {
290		ret = evtchnl_publish(xbt, &front_info->evt_pairs[conn].req,
291				      plat_data->connectors[conn].xenstore_path,
292				      XENDISPL_FIELD_REQ_RING_REF,
293				      XENDISPL_FIELD_REQ_CHANNEL);
294		if (ret < 0)
295			goto fail;
296
297		ret = evtchnl_publish(xbt, &front_info->evt_pairs[conn].evt,
298				      plat_data->connectors[conn].xenstore_path,
299				      XENDISPL_FIELD_EVT_RING_REF,
300				      XENDISPL_FIELD_EVT_CHANNEL);
301		if (ret < 0)
302			goto fail;
303	}
304
305	ret = xenbus_transaction_end(xbt, 0);
306	if (ret < 0) {
307		if (ret == -EAGAIN)
308			goto again;
309
310		xenbus_dev_fatal(front_info->xb_dev, ret,
311				 "completing transaction");
312		goto fail_to_end;
313	}
314
315	return 0;
316
317fail:
318	xenbus_transaction_end(xbt, 1);
319
320fail_to_end:
321	xenbus_dev_fatal(front_info->xb_dev, ret, "writing Xen store");
322	return ret;
323}
324
325void xen_drm_front_evtchnl_flush(struct xen_drm_front_evtchnl *evtchnl)
326{
327	int notify;
328
329	evtchnl->u.req.ring.req_prod_pvt++;
330	RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&evtchnl->u.req.ring, notify);
331	if (notify)
332		notify_remote_via_irq(evtchnl->irq);
333}
334
335void xen_drm_front_evtchnl_set_state(struct xen_drm_front_info *front_info,
336				     enum xen_drm_front_evtchnl_state state)
337{
338	unsigned long flags;
339	int i;
340
341	if (!front_info->evt_pairs)
342		return;
343
344	spin_lock_irqsave(&front_info->io_lock, flags);
345	for (i = 0; i < front_info->num_evt_pairs; i++) {
346		front_info->evt_pairs[i].req.state = state;
347		front_info->evt_pairs[i].evt.state = state;
348	}
349	spin_unlock_irqrestore(&front_info->io_lock, flags);
350}
351
352void xen_drm_front_evtchnl_free_all(struct xen_drm_front_info *front_info)
353{
354	int i;
355
356	if (!front_info->evt_pairs)
357		return;
358
359	for (i = 0; i < front_info->num_evt_pairs; i++) {
360		evtchnl_free(front_info, &front_info->evt_pairs[i].req);
361		evtchnl_free(front_info, &front_info->evt_pairs[i].evt);
362	}
363
364	kfree(front_info->evt_pairs);
365	front_info->evt_pairs = NULL;
366}
367