drivers/platform/surface/surface_aggregator_cdev.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Provides user-space access to the SSAM EC via the /dev/surface/aggregator
   4  * misc device. Intended for debugging and development.
   5  *
   6  * Copyright (C) 2020-2022 Maximilian Luz <luzmaximilian@gmail.com>
   7  */
   8
   9 #include <linux/fs.h>
  10 #include <linux/ioctl.h>
  11 #include <linux/kernel.h>
  12 #include <linux/kfifo.h>
  13 #include <linux/kref.h>
  14 #include <linux/miscdevice.h>
  15 #include <linux/module.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/poll.h>
  18 #include <linux/rwsem.h>
  19 #include <linux/slab.h>
  20 #include <linux/uaccess.h>
  21 #include <linux/vmalloc.h>
  22
  23 #include <linux/surface_aggregator/cdev.h>
  24 #include <linux/surface_aggregator/controller.h>
  25 #include <linux/surface_aggregator/serial_hub.h>
  26
  27 #define SSAM_CDEV_DEVICE_NAME   "surface_aggregator_cdev"
  28
  29
  30 /* -- Main structures. ------------------------------------------------------ */
  31
  32 enum ssam_cdev_device_state {
  33         SSAM_CDEV_DEVICE_SHUTDOWN_BIT = BIT(0),
  34 };
  35
  36 struct ssam_cdev {
  37         struct kref kref;
  38         struct rw_semaphore lock;
  39
  40         struct device *dev;
  41         struct ssam_controller *ctrl;
  42         struct miscdevice mdev;
  43         unsigned long flags;
  44
  45         struct rw_semaphore client_lock;  /* Guards client list. */
  46         struct list_head client_list;
  47 };
  48
  49 struct ssam_cdev_client;
  50
  51 struct ssam_cdev_notifier {
  52         struct ssam_cdev_client *client;
  53         struct ssam_event_notifier nf;
  54 };
  55
  56 struct ssam_cdev_client {
  57         struct ssam_cdev *cdev;
  58         struct list_head node;
  59
  60         struct mutex notifier_lock;     /* Guards notifier access for registration */
  61         struct ssam_cdev_notifier *notifier[SSH_NUM_EVENTS];
  62
  63         struct mutex read_lock;         /* Guards FIFO buffer read access */
  64         struct mutex write_lock;        /* Guards FIFO buffer write access */
  65         DECLARE_KFIFO(buffer, u8, 4096);
  66
  67         wait_queue_head_t waitq;
  68         struct fasync_struct *fasync;
  69 };
  70
  71 static void __ssam_cdev_release(struct kref *kref)
  72 {
  73         kfree(container_of(kref, struct ssam_cdev, kref));
  74 }
  75
  76 static struct ssam_cdev *ssam_cdev_get(struct ssam_cdev *cdev)
  77 {
  78         if (cdev)
  79                 kref_get(&cdev->kref);
  80
  81         return cdev;
  82 }
  83
  84 static void ssam_cdev_put(struct ssam_cdev *cdev)
  85 {
  86         if (cdev)
  87                 kref_put(&cdev->kref, __ssam_cdev_release);
  88 }
  89
  90
  91 /* -- Notifier handling. ---------------------------------------------------- */
  92
  93 static u32 ssam_cdev_notifier(struct ssam_event_notifier *nf, const struct ssam_event *in)
  94 {
  95         struct ssam_cdev_notifier *cdev_nf = container_of(nf, struct ssam_cdev_notifier, nf);
  96         struct ssam_cdev_client *client = cdev_nf->client;
  97         struct ssam_cdev_event event;
  98         size_t n = struct_size(&event, data, in->length);
  99
 100         /* Translate event. */
 101         event.target_category = in->target_category;
 102         event.target_id = in->target_id;
 103         event.command_id = in->command_id;
 104         event.instance_id = in->instance_id;
 105         event.length = in->length;
 106
 107         mutex_lock(&client->write_lock);
 108
 109         /* Make sure we have enough space. */
 110         if (kfifo_avail(&client->buffer) < n) {
 111                 dev_warn(client->cdev->dev,
 112                          "buffer full, dropping event (tc: %#04x, tid: %#04x, cid: %#04x, iid: %#04x)\n",
 113                          in->target_category, in->target_id, in->command_id, in->instance_id);
 114                 mutex_unlock(&client->write_lock);
 115                 return 0;
 116         }
 117
 118         /* Copy event header and payload. */
 119         kfifo_in(&client->buffer, (const u8 *)&event, struct_size(&event, data, 0));
 120         kfifo_in(&client->buffer, &in->data[0], in->length);
 121
 122         mutex_unlock(&client->write_lock);
 123
 124         /* Notify waiting readers. */
 125         kill_fasync(&client->fasync, SIGIO, POLL_IN);
 126         wake_up_interruptible(&client->waitq);
 127
 128         /*
 129          * Don't mark events as handled, this is the job of a proper driver and
 130          * not the debugging interface.
 131          */
 132         return 0;
 133 }
 134
 135 static int ssam_cdev_notifier_register(struct ssam_cdev_client *client, u8 tc, int priority)
 136 {
 137         const u16 rqid = ssh_tc_to_rqid(tc);
 138         const u16 event = ssh_rqid_to_event(rqid);
 139         struct ssam_cdev_notifier *nf;
 140         int status;
 141
 142         lockdep_assert_held_read(&client->cdev->lock);
 143
 144         /* Validate notifier target category. */
 145         if (!ssh_rqid_is_event(rqid))
 146                 return -EINVAL;
 147
 148         mutex_lock(&client->notifier_lock);
 149
 150         /* Check if the notifier has already been registered. */
 151         if (client->notifier[event]) {
 152                 mutex_unlock(&client->notifier_lock);
 153                 return -EEXIST;
 154         }
 155
 156         /* Allocate new notifier. */
 157         nf = kzalloc(sizeof(*nf), GFP_KERNEL);
 158         if (!nf) {
 159                 mutex_unlock(&client->notifier_lock);
 160                 return -ENOMEM;
 161         }
 162
 163         /*
 164          * Create a dummy notifier with the minimal required fields for
 165          * observer registration. Note that we can skip fully specifying event
 166          * and registry here as we do not need any matching and use silent
 167          * registration, which does not enable the corresponding event.
 168          */
 169         nf->client = client;
 170         nf->nf.base.fn = ssam_cdev_notifier;
 171         nf->nf.base.priority = priority;
 172         nf->nf.event.id.target_category = tc;
 173         nf->nf.event.mask = 0;  /* Do not do any matching. */
 174         nf->nf.flags = SSAM_EVENT_NOTIFIER_OBSERVER;
 175
 176         /* Register notifier. */
 177         status = ssam_notifier_register(client->cdev->ctrl, &nf->nf);
 178         if (status)
 179                 kfree(nf);
 180         else
 181                 client->notifier[event] = nf;
 182
 183         mutex_unlock(&client->notifier_lock);
 184         return status;
 185 }
 186
 187 static int ssam_cdev_notifier_unregister(struct ssam_cdev_client *client, u8 tc)
 188 {
 189         const u16 rqid = ssh_tc_to_rqid(tc);
 190         const u16 event = ssh_rqid_to_event(rqid);
 191         int status;
 192
 193         lockdep_assert_held_read(&client->cdev->lock);
 194
 195         /* Validate notifier target category. */
 196         if (!ssh_rqid_is_event(rqid))
 197                 return -EINVAL;
 198
 199         mutex_lock(&client->notifier_lock);
 200
 201         /* Check if the notifier is currently registered. */
 202         if (!client->notifier[event]) {
 203                 mutex_unlock(&client->notifier_lock);
 204                 return -ENOENT;
 205         }
 206
 207         /* Unregister and free notifier. */
 208         status = ssam_notifier_unregister(client->cdev->ctrl, &client->notifier[event]->nf);
 209         kfree(client->notifier[event]);
 210         client->notifier[event] = NULL;
 211
 212         mutex_unlock(&client->notifier_lock);
 213         return status;
 214 }
 215
 216 static void ssam_cdev_notifier_unregister_all(struct ssam_cdev_client *client)
 217 {
 218         int i;
 219
 220         down_read(&client->cdev->lock);
 221
 222         /*
 223          * This function may be used during shutdown, thus we need to test for
 224          * cdev->ctrl instead of the SSAM_CDEV_DEVICE_SHUTDOWN_BIT bit.
 225          */
 226         if (client->cdev->ctrl) {
 227                 for (i = 0; i < SSH_NUM_EVENTS; i++)
 228                         ssam_cdev_notifier_unregister(client, i + 1);
 229
 230         } else {
 231                 int count = 0;
 232
 233                 /*
 234                  * Device has been shut down. Any notifier remaining is a bug,
 235                  * so warn about that as this would otherwise hardly be
 236                  * noticeable. Nevertheless, free them as well.
 237                  */
 238                 mutex_lock(&client->notifier_lock);
 239                 for (i = 0; i < SSH_NUM_EVENTS; i++) {
 240                         count += !!(client->notifier[i]);
 241                         kfree(client->notifier[i]);
 242                         client->notifier[i] = NULL;
 243                 }
 244                 mutex_unlock(&client->notifier_lock);
 245
 246                 WARN_ON(count > 0);
 247         }
 248
 249         up_read(&client->cdev->lock);
 250 }
 251
 252
 253 /* -- IOCTL functions. ------------------------------------------------------ */
 254
 255 static long ssam_cdev_request(struct ssam_cdev_client *client, struct ssam_cdev_request __user *r)
 256 {
 257         struct ssam_cdev_request rqst;
 258         struct ssam_request spec = {};
 259         struct ssam_response rsp = {};
 260         const void __user *plddata;
 261         void __user *rspdata;
 262         int status = 0, ret = 0, tmp;
 263
 264         lockdep_assert_held_read(&client->cdev->lock);
 265
 266         ret = copy_struct_from_user(&rqst, sizeof(rqst), r, sizeof(*r));
 267         if (ret)
 268                 goto out;
 269
 270         plddata = u64_to_user_ptr(rqst.payload.data);
 271         rspdata = u64_to_user_ptr(rqst.response.data);
 272
 273         /* Setup basic request fields. */
 274         spec.target_category = rqst.target_category;
 275         spec.target_id = rqst.target_id;
 276         spec.command_id = rqst.command_id;
 277         spec.instance_id = rqst.instance_id;
 278         spec.flags = 0;
 279         spec.length = rqst.payload.length;
 280         spec.payload = NULL;
 281
 282         if (rqst.flags & SSAM_CDEV_REQUEST_HAS_RESPONSE)
 283                 spec.flags |= SSAM_REQUEST_HAS_RESPONSE;
 284
 285         if (rqst.flags & SSAM_CDEV_REQUEST_UNSEQUENCED)
 286                 spec.flags |= SSAM_REQUEST_UNSEQUENCED;
 287
 288         rsp.capacity = rqst.response.length;
 289         rsp.length = 0;
 290         rsp.pointer = NULL;
 291
 292         /* Get request payload from user-space. */
 293         if (spec.length) {
 294                 if (!plddata) {
 295                         ret = -EINVAL;
 296                         goto out;
 297                 }
 298
 299                 /*
 300                  * Note: spec.length is limited to U16_MAX bytes via struct
 301                  * ssam_cdev_request. This is slightly larger than the
 302                  * theoretical maximum (SSH_COMMAND_MAX_PAYLOAD_SIZE) of the
 303                  * underlying protocol (note that nothing remotely this size
 304                  * should ever be allocated in any normal case). This size is
 305                  * validated later in ssam_request_sync(), for allocation the
 306                  * bound imposed by u16 should be enough.
 307                  */
 308                 spec.payload = kzalloc(spec.length, GFP_KERNEL);
 309                 if (!spec.payload) {
 310                         ret = -ENOMEM;
 311                         goto out;
 312                 }
 313
 314                 if (copy_from_user((void *)spec.payload, plddata, spec.length)) {
 315                         ret = -EFAULT;
 316                         goto out;
 317                 }
 318         }
 319
 320         /* Allocate response buffer. */
 321         if (rsp.capacity) {
 322                 if (!rspdata) {
 323                         ret = -EINVAL;
 324                         goto out;
 325                 }
 326
 327                 /*
 328                  * Note: rsp.capacity is limited to U16_MAX bytes via struct
 329                  * ssam_cdev_request. This is slightly larger than the
 330                  * theoretical maximum (SSH_COMMAND_MAX_PAYLOAD_SIZE) of the
 331                  * underlying protocol (note that nothing remotely this size
 332                  * should ever be allocated in any normal case). In later use,
 333                  * this capacity does not have to be strictly bounded, as it
 334                  * is only used as an output buffer to be written to. For
 335                  * allocation the bound imposed by u16 should be enough.
 336                  */
 337                 rsp.pointer = kzalloc(rsp.capacity, GFP_KERNEL);
 338                 if (!rsp.pointer) {
 339                         ret = -ENOMEM;
 340                         goto out;
 341                 }
 342         }
 343
 344         /* Perform request. */
 345         status = ssam_request_sync(client->cdev->ctrl, &spec, &rsp);
 346         if (status)
 347                 goto out;
 348
 349         /* Copy response to user-space. */
 350         if (rsp.length && copy_to_user(rspdata, rsp.pointer, rsp.length))
 351                 ret = -EFAULT;
 352
 353 out:
 354         /* Always try to set response-length and status. */
 355         tmp = put_user(rsp.length, &r->response.length);
 356         if (tmp)
 357                 ret = tmp;
 358
 359         tmp = put_user(status, &r->status);
 360         if (tmp)
 361                 ret = tmp;
 362
 363         /* Cleanup. */
 364         kfree(spec.payload);
 365         kfree(rsp.pointer);
 366
 367         return ret;
 368 }
 369
 370 static long ssam_cdev_notif_register(struct ssam_cdev_client *client,
 371                                      const struct ssam_cdev_notifier_desc __user *d)
 372 {
 373         struct ssam_cdev_notifier_desc desc;
 374         long ret;
 375
 376         lockdep_assert_held_read(&client->cdev->lock);
 377
 378         ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
 379         if (ret)
 380                 return ret;
 381
 382         return ssam_cdev_notifier_register(client, desc.target_category, desc.priority);
 383 }
 384
 385 static long ssam_cdev_notif_unregister(struct ssam_cdev_client *client,
 386                                        const struct ssam_cdev_notifier_desc __user *d)
 387 {
 388         struct ssam_cdev_notifier_desc desc;
 389         long ret;
 390
 391         lockdep_assert_held_read(&client->cdev->lock);
 392
 393         ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
 394         if (ret)
 395                 return ret;
 396
 397         return ssam_cdev_notifier_unregister(client, desc.target_category);
 398 }
 399
 400 static long ssam_cdev_event_enable(struct ssam_cdev_client *client,
 401                                    const struct ssam_cdev_event_desc __user *d)
 402 {
 403         struct ssam_cdev_event_desc desc;
 404         struct ssam_event_registry reg;
 405         struct ssam_event_id id;
 406         long ret;
 407
 408         lockdep_assert_held_read(&client->cdev->lock);
 409
 410         /* Read descriptor from user-space. */
 411         ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
 412         if (ret)
 413                 return ret;
 414
 415         /* Translate descriptor. */
 416         reg.target_category = desc.reg.target_category;
 417         reg.target_id = desc.reg.target_id;
 418         reg.cid_enable = desc.reg.cid_enable;
 419         reg.cid_disable = desc.reg.cid_disable;
 420
 421         id.target_category = desc.id.target_category;
 422         id.instance = desc.id.instance;
 423
 424         /* Disable event. */
 425         return ssam_controller_event_enable(client->cdev->ctrl, reg, id, desc.flags);
 426 }
 427
 428 static long ssam_cdev_event_disable(struct ssam_cdev_client *client,
 429                                     const struct ssam_cdev_event_desc __user *d)
 430 {
 431         struct ssam_cdev_event_desc desc;
 432         struct ssam_event_registry reg;
 433         struct ssam_event_id id;
 434         long ret;
 435
 436         lockdep_assert_held_read(&client->cdev->lock);
 437
 438         /* Read descriptor from user-space. */
 439         ret = copy_struct_from_user(&desc, sizeof(desc), d, sizeof(*d));
 440         if (ret)
 441                 return ret;
 442
 443         /* Translate descriptor. */
 444         reg.target_category = desc.reg.target_category;
 445         reg.target_id = desc.reg.target_id;
 446         reg.cid_enable = desc.reg.cid_enable;
 447         reg.cid_disable = desc.reg.cid_disable;
 448
 449         id.target_category = desc.id.target_category;
 450         id.instance = desc.id.instance;
 451
 452         /* Disable event. */
 453         return ssam_controller_event_disable(client->cdev->ctrl, reg, id, desc.flags);
 454 }
 455
 456
 457 /* -- File operations. ------------------------------------------------------ */
 458
 459 static int ssam_cdev_device_open(struct inode *inode, struct file *filp)
 460 {
 461         struct miscdevice *mdev = filp->private_data;
 462         struct ssam_cdev_client *client;
 463         struct ssam_cdev *cdev = container_of(mdev, struct ssam_cdev, mdev);
 464
 465         /* Initialize client */
 466         client = vzalloc(sizeof(*client));
 467         if (!client)
 468                 return -ENOMEM;
 469
 470         client->cdev = ssam_cdev_get(cdev);
 471
 472         INIT_LIST_HEAD(&client->node);
 473
 474         mutex_init(&client->notifier_lock);
 475
 476         mutex_init(&client->read_lock);
 477         mutex_init(&client->write_lock);
 478         INIT_KFIFO(client->buffer);
 479         init_waitqueue_head(&client->waitq);
 480
 481         filp->private_data = client;
 482
 483         /* Attach client. */
 484         down_write(&cdev->client_lock);
 485
 486         if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags)) {
 487                 up_write(&cdev->client_lock);
 488                 mutex_destroy(&client->write_lock);
 489                 mutex_destroy(&client->read_lock);
 490                 mutex_destroy(&client->notifier_lock);
 491                 ssam_cdev_put(client->cdev);
 492                 vfree(client);
 493                 return -ENODEV;
 494         }
 495         list_add_tail(&client->node, &cdev->client_list);
 496
 497         up_write(&cdev->client_lock);
 498
 499         stream_open(inode, filp);
 500         return 0;
 501 }
 502
 503 static int ssam_cdev_device_release(struct inode *inode, struct file *filp)
 504 {
 505         struct ssam_cdev_client *client = filp->private_data;
 506
 507         /* Force-unregister all remaining notifiers of this client. */
 508         ssam_cdev_notifier_unregister_all(client);
 509
 510         /* Detach client. */
 511         down_write(&client->cdev->client_lock);
 512         list_del(&client->node);
 513         up_write(&client->cdev->client_lock);
 514
 515         /* Free client. */
 516         mutex_destroy(&client->write_lock);
 517         mutex_destroy(&client->read_lock);
 518
 519         mutex_destroy(&client->notifier_lock);
 520
 521         ssam_cdev_put(client->cdev);
 522         vfree(client);
 523
 524         return 0;
 525 }
 526
 527 static long __ssam_cdev_device_ioctl(struct ssam_cdev_client *client, unsigned int cmd,
 528                                      unsigned long arg)
 529 {
 530         lockdep_assert_held_read(&client->cdev->lock);
 531
 532         switch (cmd) {
 533         case SSAM_CDEV_REQUEST:
 534                 return ssam_cdev_request(client, (struct ssam_cdev_request __user *)arg);
 535
 536         case SSAM_CDEV_NOTIF_REGISTER:
 537                 return ssam_cdev_notif_register(client,
 538                                                 (struct ssam_cdev_notifier_desc __user *)arg);
 539
 540         case SSAM_CDEV_NOTIF_UNREGISTER:
 541                 return ssam_cdev_notif_unregister(client,
 542                                                   (struct ssam_cdev_notifier_desc __user *)arg);
 543
 544         case SSAM_CDEV_EVENT_ENABLE:
 545                 return ssam_cdev_event_enable(client, (struct ssam_cdev_event_desc __user *)arg);
 546
 547         case SSAM_CDEV_EVENT_DISABLE:
 548                 return ssam_cdev_event_disable(client, (struct ssam_cdev_event_desc __user *)arg);
 549
 550         default:
 551                 return -ENOTTY;
 552         }
 553 }
 554
 555 static long ssam_cdev_device_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 556 {
 557         struct ssam_cdev_client *client = file->private_data;
 558         long status;
 559
 560         /* Ensure that controller is valid for as long as we need it. */
 561         if (down_read_killable(&client->cdev->lock))
 562                 return -ERESTARTSYS;
 563
 564         if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &client->cdev->flags)) {
 565                 up_read(&client->cdev->lock);
 566                 return -ENODEV;
 567         }
 568
 569         status = __ssam_cdev_device_ioctl(client, cmd, arg);
 570
 571         up_read(&client->cdev->lock);
 572         return status;
 573 }
 574
 575 static ssize_t ssam_cdev_read(struct file *file, char __user *buf, size_t count, loff_t *offs)
 576 {
 577         struct ssam_cdev_client *client = file->private_data;
 578         struct ssam_cdev *cdev = client->cdev;
 579         unsigned int copied;
 580         int status = 0;
 581
 582         if (down_read_killable(&cdev->lock))
 583                 return -ERESTARTSYS;
 584
 585         /* Make sure we're not shut down. */
 586         if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags)) {
 587                 up_read(&cdev->lock);
 588                 return -ENODEV;
 589         }
 590
 591         do {
 592                 /* Check availability, wait if necessary. */
 593                 if (kfifo_is_empty(&client->buffer)) {
 594                         up_read(&cdev->lock);
 595
 596                         if (file->f_flags & O_NONBLOCK)
 597                                 return -EAGAIN;
 598
 599                         status = wait_event_interruptible(client->waitq,
 600                                                           !kfifo_is_empty(&client->buffer) ||
 601                                                           test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT,
 602                                                                    &cdev->flags));
 603                         if (status < 0)
 604                                 return status;
 605
 606                         if (down_read_killable(&cdev->lock))
 607                                 return -ERESTARTSYS;
 608
 609                         /* Need to check that we're not shut down again. */
 610                         if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags)) {
 611                                 up_read(&cdev->lock);
 612                                 return -ENODEV;
 613                         }
 614                 }
 615
 616                 /* Try to read from FIFO. */
 617                 if (mutex_lock_interruptible(&client->read_lock)) {
 618                         up_read(&cdev->lock);
 619                         return -ERESTARTSYS;
 620                 }
 621
 622                 status = kfifo_to_user(&client->buffer, buf, count, &copied);
 623                 mutex_unlock(&client->read_lock);
 624
 625                 if (status < 0) {
 626                         up_read(&cdev->lock);
 627                         return status;
 628                 }
 629
 630                 /* We might not have gotten anything, check this here. */
 631                 if (copied == 0 && (file->f_flags & O_NONBLOCK)) {
 632                         up_read(&cdev->lock);
 633                         return -EAGAIN;
 634                 }
 635         } while (copied == 0);
 636
 637         up_read(&cdev->lock);
 638         return copied;
 639 }
 640
 641 static __poll_t ssam_cdev_poll(struct file *file, struct poll_table_struct *pt)
 642 {
 643         struct ssam_cdev_client *client = file->private_data;
 644         __poll_t events = 0;
 645
 646         if (test_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &client->cdev->flags))
 647                 return EPOLLHUP | EPOLLERR;
 648
 649         poll_wait(file, &client->waitq, pt);
 650
 651         if (!kfifo_is_empty(&client->buffer))
 652                 events |= EPOLLIN | EPOLLRDNORM;
 653
 654         return events;
 655 }
 656
 657 static int ssam_cdev_fasync(int fd, struct file *file, int on)
 658 {
 659         struct ssam_cdev_client *client = file->private_data;
 660
 661         return fasync_helper(fd, file, on, &client->fasync);
 662 }
 663
 664 static const struct file_operations ssam_controller_fops = {
 665         .owner          = THIS_MODULE,
 666         .open           = ssam_cdev_device_open,
 667         .release        = ssam_cdev_device_release,
 668         .read           = ssam_cdev_read,
 669         .poll           = ssam_cdev_poll,
 670         .fasync         = ssam_cdev_fasync,
 671         .unlocked_ioctl = ssam_cdev_device_ioctl,
 672         .compat_ioctl   = ssam_cdev_device_ioctl,
 673         .llseek         = no_llseek,
 674 };
 675
 676
 677 /* -- Device and driver setup ----------------------------------------------- */
 678
 679 static int ssam_dbg_device_probe(struct platform_device *pdev)
 680 {
 681         struct ssam_controller *ctrl;
 682         struct ssam_cdev *cdev;
 683         int status;
 684
 685         ctrl = ssam_client_bind(&pdev->dev);
 686         if (IS_ERR(ctrl))
 687                 return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl);
 688
 689         cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
 690         if (!cdev)
 691                 return -ENOMEM;
 692
 693         kref_init(&cdev->kref);
 694         init_rwsem(&cdev->lock);
 695         cdev->ctrl = ctrl;
 696         cdev->dev = &pdev->dev;
 697
 698         cdev->mdev.parent   = &pdev->dev;
 699         cdev->mdev.minor    = MISC_DYNAMIC_MINOR;
 700         cdev->mdev.name     = "surface_aggregator";
 701         cdev->mdev.nodename = "surface/aggregator";
 702         cdev->mdev.fops     = &ssam_controller_fops;
 703
 704         init_rwsem(&cdev->client_lock);
 705         INIT_LIST_HEAD(&cdev->client_list);
 706
 707         status = misc_register(&cdev->mdev);
 708         if (status) {
 709                 kfree(cdev);
 710                 return status;
 711         }
 712
 713         platform_set_drvdata(pdev, cdev);
 714         return 0;
 715 }
 716
 717 static int ssam_dbg_device_remove(struct platform_device *pdev)
 718 {
 719         struct ssam_cdev *cdev = platform_get_drvdata(pdev);
 720         struct ssam_cdev_client *client;
 721
 722         /*
 723          * Mark device as shut-down. Prevent new clients from being added and
 724          * new operations from being executed.
 725          */
 726         set_bit(SSAM_CDEV_DEVICE_SHUTDOWN_BIT, &cdev->flags);
 727
 728         down_write(&cdev->client_lock);
 729
 730         /* Remove all notifiers registered by us. */
 731         list_for_each_entry(client, &cdev->client_list, node) {
 732                 ssam_cdev_notifier_unregister_all(client);
 733         }
 734
 735         /* Wake up async clients. */
 736         list_for_each_entry(client, &cdev->client_list, node) {
 737                 kill_fasync(&client->fasync, SIGIO, POLL_HUP);
 738         }
 739
 740         /* Wake up blocking clients. */
 741         list_for_each_entry(client, &cdev->client_list, node) {
 742                 wake_up_interruptible(&client->waitq);
 743         }
 744
 745         up_write(&cdev->client_lock);
 746
 747         /*
 748          * The controller is only guaranteed to be valid for as long as the
 749          * driver is bound. Remove controller so that any lingering open files
 750          * cannot access it any more after we're gone.
 751          */
 752         down_write(&cdev->lock);
 753         cdev->ctrl = NULL;
 754         cdev->dev = NULL;
 755         up_write(&cdev->lock);
 756
 757         misc_deregister(&cdev->mdev);
 758
 759         ssam_cdev_put(cdev);
 760         return 0;
 761 }
 762
 763 static struct platform_device *ssam_cdev_device;
 764
 765 static struct platform_driver ssam_cdev_driver = {
 766         .probe = ssam_dbg_device_probe,
 767         .remove = ssam_dbg_device_remove,
 768         .driver = {
 769                 .name = SSAM_CDEV_DEVICE_NAME,
 770                 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
 771         },
 772 };
 773
 774 static int __init ssam_debug_init(void)
 775 {
 776         int status;
 777
 778         ssam_cdev_device = platform_device_alloc(SSAM_CDEV_DEVICE_NAME,
 779                                                  PLATFORM_DEVID_NONE);
 780         if (!ssam_cdev_device)
 781                 return -ENOMEM;
 782
 783         status = platform_device_add(ssam_cdev_device);
 784         if (status)
 785                 goto err_device;
 786
 787         status = platform_driver_register(&ssam_cdev_driver);
 788         if (status)
 789                 goto err_driver;
 790
 791         return 0;
 792
 793 err_driver:
 794         platform_device_del(ssam_cdev_device);
 795 err_device:
 796         platform_device_put(ssam_cdev_device);
 797         return status;
 798 }
 799 module_init(ssam_debug_init);
 800
 801 static void __exit ssam_debug_exit(void)
 802 {
 803         platform_driver_unregister(&ssam_cdev_driver);
 804         platform_device_unregister(ssam_cdev_device);
 805 }
 806 module_exit(ssam_debug_exit);
 807
 808 MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
 809 MODULE_DESCRIPTION("User-space interface for Surface System Aggregator Module");
 810 MODULE_LICENSE("GPL");