drivers/gpu/drm/xen/xen_drm_front_evtchnl.c

   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
  23 static 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
  36 again:
  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
  81 static 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
 118 out:
 119         spin_unlock_irqrestore(&front_info->io_lock, flags);
 120         return IRQ_HANDLED;
 121 }
 122
 123 static 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
 156 static 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
 223 fail:
 224         DRM_ERROR("Failed to allocate ring: %d\n", ret);
 225         return ret;
 226 }
 227
 228 int 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
 264 fail:
 265         xen_drm_front_evtchnl_free_all(front_info);
 266         return ret;
 267 }
 268
 269 static 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
 294 int 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
 302 again:
 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
 338 fail:
 339         xenbus_transaction_end(xbt, 1);
 340
 341 fail_to_end:
 342         xenbus_dev_fatal(front_info->xb_dev, ret, "writing Xen store");
 343         return ret;
 344 }
 345
 346 void 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
 356 void 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
 373 void 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 }