1// SPDX-License-Identifier: GPL-2.0+ 2/* 3 * Surface Book (gen. 2 and later) detachment system (DTX) driver. 4 * 5 * Provides a user-space interface to properly handle clipboard/tablet 6 * (containing screen and processor) detachment from the base of the device 7 * (containing the keyboard and optionally a discrete GPU). Allows to 8 * acknowledge (to speed things up), abort (e.g. in case the dGPU is still in 9 * use), or request detachment via user-space. 10 * 11 * Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com> 12 */ 13 14#include <linux/fs.h> 15#include <linux/input.h> 16#include <linux/ioctl.h> 17#include <linux/kernel.h> 18#include <linux/kfifo.h> 19#include <linux/kref.h> 20#include <linux/miscdevice.h> 21#include <linux/module.h> 22#include <linux/mutex.h> 23#include <linux/platform_device.h> 24#include <linux/poll.h> 25#include <linux/rwsem.h> 26#include <linux/slab.h> 27#include <linux/workqueue.h> 28 29#include <linux/surface_aggregator/controller.h> 30#include <linux/surface_aggregator/device.h> 31#include <linux/surface_aggregator/dtx.h> 32 33 34/* -- SSAM interface. ------------------------------------------------------- */ 35 36enum sam_event_cid_bas { 37 SAM_EVENT_CID_DTX_CONNECTION = 0x0c, 38 SAM_EVENT_CID_DTX_REQUEST = 0x0e, 39 SAM_EVENT_CID_DTX_CANCEL = 0x0f, 40 SAM_EVENT_CID_DTX_LATCH_STATUS = 0x11, 41}; 42 43enum ssam_bas_base_state { 44 SSAM_BAS_BASE_STATE_DETACH_SUCCESS = 0x00, 45 SSAM_BAS_BASE_STATE_ATTACHED = 0x01, 46 SSAM_BAS_BASE_STATE_NOT_FEASIBLE = 0x02, 47}; 48 49enum ssam_bas_latch_status { 50 SSAM_BAS_LATCH_STATUS_CLOSED = 0x00, 51 SSAM_BAS_LATCH_STATUS_OPENED = 0x01, 52 SSAM_BAS_LATCH_STATUS_FAILED_TO_OPEN = 0x02, 53 SSAM_BAS_LATCH_STATUS_FAILED_TO_REMAIN_OPEN = 0x03, 54 SSAM_BAS_LATCH_STATUS_FAILED_TO_CLOSE = 0x04, 55}; 56 57enum ssam_bas_cancel_reason { 58 SSAM_BAS_CANCEL_REASON_NOT_FEASIBLE = 0x00, /* Low battery. */ 59 SSAM_BAS_CANCEL_REASON_TIMEOUT = 0x02, 60 SSAM_BAS_CANCEL_REASON_FAILED_TO_OPEN = 0x03, 61 SSAM_BAS_CANCEL_REASON_FAILED_TO_REMAIN_OPEN = 0x04, 62 SSAM_BAS_CANCEL_REASON_FAILED_TO_CLOSE = 0x05, 63}; 64 65struct ssam_bas_base_info { 66 u8 state; 67 u8 base_id; 68} __packed; 69 70static_assert(sizeof(struct ssam_bas_base_info) == 2); 71 72SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_lock, { 73 .target_category = SSAM_SSH_TC_BAS, 74 .target_id = SSAM_SSH_TID_SAM, 75 .command_id = 0x06, 76 .instance_id = 0x00, 77}); 78 79SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_unlock, { 80 .target_category = SSAM_SSH_TC_BAS, 81 .target_id = SSAM_SSH_TID_SAM, 82 .command_id = 0x07, 83 .instance_id = 0x00, 84}); 85 86SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_request, { 87 .target_category = SSAM_SSH_TC_BAS, 88 .target_id = SSAM_SSH_TID_SAM, 89 .command_id = 0x08, 90 .instance_id = 0x00, 91}); 92 93SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_confirm, { 94 .target_category = SSAM_SSH_TC_BAS, 95 .target_id = SSAM_SSH_TID_SAM, 96 .command_id = 0x09, 97 .instance_id = 0x00, 98}); 99 100SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_heartbeat, { 101 .target_category = SSAM_SSH_TC_BAS, 102 .target_id = SSAM_SSH_TID_SAM, 103 .command_id = 0x0a, 104 .instance_id = 0x00, 105}); 106 107SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_cancel, { 108 .target_category = SSAM_SSH_TC_BAS, 109 .target_id = SSAM_SSH_TID_SAM, 110 .command_id = 0x0b, 111 .instance_id = 0x00, 112}); 113 114SSAM_DEFINE_SYNC_REQUEST_R(ssam_bas_get_base, struct ssam_bas_base_info, { 115 .target_category = SSAM_SSH_TC_BAS, 116 .target_id = SSAM_SSH_TID_SAM, 117 .command_id = 0x0c, 118 .instance_id = 0x00, 119}); 120 121SSAM_DEFINE_SYNC_REQUEST_R(ssam_bas_get_device_mode, u8, { 122 .target_category = SSAM_SSH_TC_BAS, 123 .target_id = SSAM_SSH_TID_SAM, 124 .command_id = 0x0d, 125 .instance_id = 0x00, 126}); 127 128SSAM_DEFINE_SYNC_REQUEST_R(ssam_bas_get_latch_status, u8, { 129 .target_category = SSAM_SSH_TC_BAS, 130 .target_id = SSAM_SSH_TID_SAM, 131 .command_id = 0x11, 132 .instance_id = 0x00, 133}); 134 135 136/* -- Main structures. ------------------------------------------------------ */ 137 138enum sdtx_device_state { 139 SDTX_DEVICE_SHUTDOWN_BIT = BIT(0), 140 SDTX_DEVICE_DIRTY_BASE_BIT = BIT(1), 141 SDTX_DEVICE_DIRTY_MODE_BIT = BIT(2), 142 SDTX_DEVICE_DIRTY_LATCH_BIT = BIT(3), 143}; 144 145struct sdtx_device { 146 struct kref kref; 147 struct rw_semaphore lock; /* Guards device and controller reference. */ 148 149 struct device *dev; 150 struct ssam_controller *ctrl; 151 unsigned long flags; 152 153 struct miscdevice mdev; 154 wait_queue_head_t waitq; 155 struct mutex write_lock; /* Guards order of events/notifications. */ 156 struct rw_semaphore client_lock; /* Guards client list. */ 157 struct list_head client_list; 158 159 struct delayed_work state_work; 160 struct { 161 struct ssam_bas_base_info base; 162 u8 device_mode; 163 u8 latch_status; 164 } state; 165 166 struct delayed_work mode_work; 167 struct input_dev *mode_switch; 168 169 struct ssam_event_notifier notif; 170}; 171 172enum sdtx_client_state { 173 SDTX_CLIENT_EVENTS_ENABLED_BIT = BIT(0), 174}; 175 176struct sdtx_client { 177 struct sdtx_device *ddev; 178 struct list_head node; 179 unsigned long flags; 180 181 struct fasync_struct *fasync; 182 183 struct mutex read_lock; /* Guards FIFO buffer read access. */ 184 DECLARE_KFIFO(buffer, u8, 512); 185}; 186 187static void __sdtx_device_release(struct kref *kref) 188{ 189 struct sdtx_device *ddev = container_of(kref, struct sdtx_device, kref); 190 191 mutex_destroy(&ddev->write_lock); 192 kfree(ddev); 193} 194 195static struct sdtx_device *sdtx_device_get(struct sdtx_device *ddev) 196{ 197 if (ddev) 198 kref_get(&ddev->kref); 199 200 return ddev; 201} 202 203static void sdtx_device_put(struct sdtx_device *ddev) 204{ 205 if (ddev) 206 kref_put(&ddev->kref, __sdtx_device_release); 207} 208 209 210/* -- Firmware value translations. ------------------------------------------ */ 211 212static u16 sdtx_translate_base_state(struct sdtx_device *ddev, u8 state) 213{ 214 switch (state) { 215 case SSAM_BAS_BASE_STATE_ATTACHED: 216 return SDTX_BASE_ATTACHED; 217 218 case SSAM_BAS_BASE_STATE_DETACH_SUCCESS: 219 return SDTX_BASE_DETACHED; 220 221 case SSAM_BAS_BASE_STATE_NOT_FEASIBLE: 222 return SDTX_DETACH_NOT_FEASIBLE; 223 224 default: 225 dev_err(ddev->dev, "unknown base state: %#04x\n", state); 226 return SDTX_UNKNOWN(state); 227 } 228} 229 230static u16 sdtx_translate_latch_status(struct sdtx_device *ddev, u8 status) 231{ 232 switch (status) { 233 case SSAM_BAS_LATCH_STATUS_CLOSED: 234 return SDTX_LATCH_CLOSED; 235 236 case SSAM_BAS_LATCH_STATUS_OPENED: 237 return SDTX_LATCH_OPENED; 238 239 case SSAM_BAS_LATCH_STATUS_FAILED_TO_OPEN: 240 return SDTX_ERR_FAILED_TO_OPEN; 241 242 case SSAM_BAS_LATCH_STATUS_FAILED_TO_REMAIN_OPEN: 243 return SDTX_ERR_FAILED_TO_REMAIN_OPEN; 244 245 case SSAM_BAS_LATCH_STATUS_FAILED_TO_CLOSE: 246 return SDTX_ERR_FAILED_TO_CLOSE; 247 248 default: 249 dev_err(ddev->dev, "unknown latch status: %#04x\n", status); 250 return SDTX_UNKNOWN(status); 251 } 252} 253 254static u16 sdtx_translate_cancel_reason(struct sdtx_device *ddev, u8 reason) 255{ 256 switch (reason) { 257 case SSAM_BAS_CANCEL_REASON_NOT_FEASIBLE: 258 return SDTX_DETACH_NOT_FEASIBLE; 259 260 case SSAM_BAS_CANCEL_REASON_TIMEOUT: 261 return SDTX_DETACH_TIMEDOUT; 262 263 case SSAM_BAS_CANCEL_REASON_FAILED_TO_OPEN: 264 return SDTX_ERR_FAILED_TO_OPEN; 265 266 case SSAM_BAS_CANCEL_REASON_FAILED_TO_REMAIN_OPEN: 267 return SDTX_ERR_FAILED_TO_REMAIN_OPEN; 268 269 case SSAM_BAS_CANCEL_REASON_FAILED_TO_CLOSE: 270 return SDTX_ERR_FAILED_TO_CLOSE; 271 272 default: 273 dev_err(ddev->dev, "unknown cancel reason: %#04x\n", reason); 274 return SDTX_UNKNOWN(reason); 275 } 276} 277 278 279/* -- IOCTLs. --------------------------------------------------------------- */ 280 281static int sdtx_ioctl_get_base_info(struct sdtx_device *ddev, 282 struct sdtx_base_info __user *buf) 283{ 284 struct ssam_bas_base_info raw; 285 struct sdtx_base_info info; 286 int status; 287 288 lockdep_assert_held_read(&ddev->lock); 289 290 status = ssam_retry(ssam_bas_get_base, ddev->ctrl, &raw); 291 if (status < 0) 292 return status; 293 294 info.state = sdtx_translate_base_state(ddev, raw.state); 295 info.base_id = SDTX_BASE_TYPE_SSH(raw.base_id); 296 297 if (copy_to_user(buf, &info, sizeof(info))) 298 return -EFAULT; 299 300 return 0; 301} 302 303static int sdtx_ioctl_get_device_mode(struct sdtx_device *ddev, u16 __user *buf) 304{ 305 u8 mode; 306 int status; 307 308 lockdep_assert_held_read(&ddev->lock); 309 310 status = ssam_retry(ssam_bas_get_device_mode, ddev->ctrl, &mode); 311 if (status < 0) 312 return status; 313 314 return put_user(mode, buf); 315} 316 317static int sdtx_ioctl_get_latch_status(struct sdtx_device *ddev, u16 __user *buf) 318{ 319 u8 latch; 320 int status; 321 322 lockdep_assert_held_read(&ddev->lock); 323 324 status = ssam_retry(ssam_bas_get_latch_status, ddev->ctrl, &latch); 325 if (status < 0) 326 return status; 327 328 return put_user(sdtx_translate_latch_status(ddev, latch), buf); 329} 330 331static long __surface_dtx_ioctl(struct sdtx_client *client, unsigned int cmd, unsigned long arg) 332{ 333 struct sdtx_device *ddev = client->ddev; 334 335 lockdep_assert_held_read(&ddev->lock); 336 337 switch (cmd) { 338 case SDTX_IOCTL_EVENTS_ENABLE: 339 set_bit(SDTX_CLIENT_EVENTS_ENABLED_BIT, &client->flags); 340 return 0; 341 342 case SDTX_IOCTL_EVENTS_DISABLE: 343 clear_bit(SDTX_CLIENT_EVENTS_ENABLED_BIT, &client->flags); 344 return 0; 345 346 case SDTX_IOCTL_LATCH_LOCK: 347 return ssam_retry(ssam_bas_latch_lock, ddev->ctrl); 348 349 case SDTX_IOCTL_LATCH_UNLOCK: 350 return ssam_retry(ssam_bas_latch_unlock, ddev->ctrl); 351 352 case SDTX_IOCTL_LATCH_REQUEST: 353 return ssam_retry(ssam_bas_latch_request, ddev->ctrl); 354 355 case SDTX_IOCTL_LATCH_CONFIRM: 356 return ssam_retry(ssam_bas_latch_confirm, ddev->ctrl); 357 358 case SDTX_IOCTL_LATCH_HEARTBEAT: 359 return ssam_retry(ssam_bas_latch_heartbeat, ddev->ctrl); 360 361 case SDTX_IOCTL_LATCH_CANCEL: 362 return ssam_retry(ssam_bas_latch_cancel, ddev->ctrl); 363 364 case SDTX_IOCTL_GET_BASE_INFO: 365 return sdtx_ioctl_get_base_info(ddev, (struct sdtx_base_info __user *)arg); 366 367 case SDTX_IOCTL_GET_DEVICE_MODE: 368 return sdtx_ioctl_get_device_mode(ddev, (u16 __user *)arg); 369 370 case SDTX_IOCTL_GET_LATCH_STATUS: 371 return sdtx_ioctl_get_latch_status(ddev, (u16 __user *)arg); 372 373 default: 374 return -EINVAL; 375 } 376} 377 378static long surface_dtx_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 379{ 380 struct sdtx_client *client = file->private_data; 381 long status; 382 383 if (down_read_killable(&client->ddev->lock)) 384 return -ERESTARTSYS; 385 386 if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &client->ddev->flags)) { 387 up_read(&client->ddev->lock); 388 return -ENODEV; 389 } 390 391 status = __surface_dtx_ioctl(client, cmd, arg); 392 393 up_read(&client->ddev->lock); 394 return status; 395} 396 397 398/* -- File operations. ------------------------------------------------------ */ 399 400static int surface_dtx_open(struct inode *inode, struct file *file) 401{ 402 struct sdtx_device *ddev = container_of(file->private_data, struct sdtx_device, mdev); 403 struct sdtx_client *client; 404 405 /* Initialize client. */ 406 client = kzalloc(sizeof(*client), GFP_KERNEL); 407 if (!client) 408 return -ENOMEM; 409 410 client->ddev = sdtx_device_get(ddev); 411 412 INIT_LIST_HEAD(&client->node); 413 414 mutex_init(&client->read_lock); 415 INIT_KFIFO(client->buffer); 416 417 file->private_data = client; 418 419 /* Attach client. */ 420 down_write(&ddev->client_lock); 421 422 /* 423 * Do not add a new client if the device has been shut down. Note that 424 * it's enough to hold the client_lock here as, during shutdown, we 425 * only acquire that lock and remove clients after marking the device 426 * as shut down. 427 */ 428 if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &ddev->flags)) { 429 up_write(&ddev->client_lock); 430 mutex_destroy(&client->read_lock); 431 sdtx_device_put(client->ddev); 432 kfree(client); 433 return -ENODEV; 434 } 435 436 list_add_tail(&client->node, &ddev->client_list); 437 up_write(&ddev->client_lock); 438 439 stream_open(inode, file); 440 return 0; 441} 442 443static int surface_dtx_release(struct inode *inode, struct file *file) 444{ 445 struct sdtx_client *client = file->private_data; 446 447 /* Detach client. */ 448 down_write(&client->ddev->client_lock); 449 list_del(&client->node); 450 up_write(&client->ddev->client_lock); 451 452 /* Free client. */ 453 sdtx_device_put(client->ddev); 454 mutex_destroy(&client->read_lock); 455 kfree(client); 456 457 return 0; 458} 459 460static ssize_t surface_dtx_read(struct file *file, char __user *buf, size_t count, loff_t *offs) 461{ 462 struct sdtx_client *client = file->private_data; 463 struct sdtx_device *ddev = client->ddev; 464 unsigned int copied; 465 int status = 0; 466 467 if (down_read_killable(&ddev->lock)) 468 return -ERESTARTSYS; 469 470 /* Make sure we're not shut down. */ 471 if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &ddev->flags)) { 472 up_read(&ddev->lock); 473 return -ENODEV; 474 } 475 476 do { 477 /* Check availability, wait if necessary. */ 478 if (kfifo_is_empty(&client->buffer)) { 479 up_read(&ddev->lock); 480 481 if (file->f_flags & O_NONBLOCK) 482 return -EAGAIN; 483 484 status = wait_event_interruptible(ddev->waitq, 485 !kfifo_is_empty(&client->buffer) || 486 test_bit(SDTX_DEVICE_SHUTDOWN_BIT, 487 &ddev->flags)); 488 if (status < 0) 489 return status; 490 491 if (down_read_killable(&ddev->lock)) 492 return -ERESTARTSYS; 493 494 /* Need to check that we're not shut down again. */ 495 if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &ddev->flags)) { 496 up_read(&ddev->lock); 497 return -ENODEV; 498 } 499 } 500 501 /* Try to read from FIFO. */ 502 if (mutex_lock_interruptible(&client->read_lock)) { 503 up_read(&ddev->lock); 504 return -ERESTARTSYS; 505 } 506 507 status = kfifo_to_user(&client->buffer, buf, count, &copied); 508 mutex_unlock(&client->read_lock); 509 510 if (status < 0) { 511 up_read(&ddev->lock); 512 return status; 513 } 514 515 /* We might not have gotten anything, check this here. */ 516 if (copied == 0 && (file->f_flags & O_NONBLOCK)) { 517 up_read(&ddev->lock); 518 return -EAGAIN; 519 } 520 } while (copied == 0); 521 522 up_read(&ddev->lock); 523 return copied; 524} 525 526static __poll_t surface_dtx_poll(struct file *file, struct poll_table_struct *pt) 527{ 528 struct sdtx_client *client = file->private_data; 529 __poll_t events = 0; 530 531 if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &client->ddev->flags)) 532 return EPOLLHUP | EPOLLERR; 533 534 poll_wait(file, &client->ddev->waitq, pt); 535 536 if (!kfifo_is_empty(&client->buffer)) 537 events |= EPOLLIN | EPOLLRDNORM; 538 539 return events; 540} 541 542static int surface_dtx_fasync(int fd, struct file *file, int on) 543{ 544 struct sdtx_client *client = file->private_data; 545 546 return fasync_helper(fd, file, on, &client->fasync); 547} 548 549static const struct file_operations surface_dtx_fops = { 550 .owner = THIS_MODULE, 551 .open = surface_dtx_open, 552 .release = surface_dtx_release, 553 .read = surface_dtx_read, 554 .poll = surface_dtx_poll, 555 .fasync = surface_dtx_fasync, 556 .unlocked_ioctl = surface_dtx_ioctl, 557 .compat_ioctl = surface_dtx_ioctl, 558 .llseek = no_llseek, 559}; 560 561 562/* -- Event handling/forwarding. -------------------------------------------- */ 563 564/* 565 * The device operation mode is not immediately updated on the EC when the 566 * base has been connected, i.e. querying the device mode inside the 567 * connection event callback yields an outdated value. Thus, we can only 568 * determine the new tablet-mode switch and device mode values after some 569 * time. 570 * 571 * These delays have been chosen by experimenting. We first delay on connect 572 * events, then check and validate the device mode against the base state and 573 * if invalid delay again by the "recheck" delay. 574 */ 575#define SDTX_DEVICE_MODE_DELAY_CONNECT msecs_to_jiffies(100) 576#define SDTX_DEVICE_MODE_DELAY_RECHECK msecs_to_jiffies(100) 577 578struct sdtx_status_event { 579 struct sdtx_event e; 580 __u16 v; 581} __packed; 582 583struct sdtx_base_info_event { 584 struct sdtx_event e; 585 struct sdtx_base_info v; 586} __packed; 587 588union sdtx_generic_event { 589 struct sdtx_event common; 590 struct sdtx_status_event status; 591 struct sdtx_base_info_event base; 592}; 593 594static void sdtx_update_device_mode(struct sdtx_device *ddev, unsigned long delay); 595 596/* Must be executed with ddev->write_lock held. */ 597static void sdtx_push_event(struct sdtx_device *ddev, struct sdtx_event *evt) 598{ 599 const size_t len = sizeof(struct sdtx_event) + evt->length; 600 struct sdtx_client *client; 601 602 lockdep_assert_held(&ddev->write_lock); 603 604 down_read(&ddev->client_lock); 605 list_for_each_entry(client, &ddev->client_list, node) { 606 if (!test_bit(SDTX_CLIENT_EVENTS_ENABLED_BIT, &client->flags)) 607 continue; 608 609 if (likely(kfifo_avail(&client->buffer) >= len)) 610 kfifo_in(&client->buffer, (const u8 *)evt, len); 611 else 612 dev_warn(ddev->dev, "event buffer overrun\n"); 613 614 kill_fasync(&client->fasync, SIGIO, POLL_IN); 615 } 616 up_read(&ddev->client_lock); 617 618 wake_up_interruptible(&ddev->waitq); 619} 620 621static u32 sdtx_notifier(struct ssam_event_notifier *nf, const struct ssam_event *in) 622{ 623 struct sdtx_device *ddev = container_of(nf, struct sdtx_device, notif); 624 union sdtx_generic_event event; 625 size_t len; 626 627 /* Validate event payload length. */ 628 switch (in->command_id) { 629 case SAM_EVENT_CID_DTX_CONNECTION: 630 len = 2 * sizeof(u8); 631 break; 632 633 case SAM_EVENT_CID_DTX_REQUEST: 634 len = 0; 635 break; 636 637 case SAM_EVENT_CID_DTX_CANCEL: 638 len = sizeof(u8); 639 break; 640 641 case SAM_EVENT_CID_DTX_LATCH_STATUS: 642 len = sizeof(u8); 643 break; 644 645 default: 646 return 0; 647 } 648 649 if (in->length != len) { 650 dev_err(ddev->dev, 651 "unexpected payload size for event %#04x: got %u, expected %zu\n", 652 in->command_id, in->length, len); 653 return 0; 654 } 655 656 mutex_lock(&ddev->write_lock); 657 658 /* Translate event. */ 659 switch (in->command_id) { 660 case SAM_EVENT_CID_DTX_CONNECTION: 661 clear_bit(SDTX_DEVICE_DIRTY_BASE_BIT, &ddev->flags); 662 663 /* If state has not changed: do not send new event. */ 664 if (ddev->state.base.state == in->data[0] && 665 ddev->state.base.base_id == in->data[1]) 666 goto out; 667 668 ddev->state.base.state = in->data[0]; 669 ddev->state.base.base_id = in->data[1]; 670 671 event.base.e.length = sizeof(struct sdtx_base_info); 672 event.base.e.code = SDTX_EVENT_BASE_CONNECTION; 673 event.base.v.state = sdtx_translate_base_state(ddev, in->data[0]); 674 event.base.v.base_id = SDTX_BASE_TYPE_SSH(in->data[1]); 675 break; 676 677 case SAM_EVENT_CID_DTX_REQUEST: 678 event.common.code = SDTX_EVENT_REQUEST; 679 event.common.length = 0; 680 break; 681 682 case SAM_EVENT_CID_DTX_CANCEL: 683 event.status.e.length = sizeof(u16); 684 event.status.e.code = SDTX_EVENT_CANCEL; 685 event.status.v = sdtx_translate_cancel_reason(ddev, in->data[0]); 686 break; 687 688 case SAM_EVENT_CID_DTX_LATCH_STATUS: 689 clear_bit(SDTX_DEVICE_DIRTY_LATCH_BIT, &ddev->flags); 690 691 /* If state has not changed: do not send new event. */ 692 if (ddev->state.latch_status == in->data[0]) 693 goto out; 694 695 ddev->state.latch_status = in->data[0]; 696 697 event.status.e.length = sizeof(u16); 698 event.status.e.code = SDTX_EVENT_LATCH_STATUS; 699 event.status.v = sdtx_translate_latch_status(ddev, in->data[0]); 700 break; 701 } 702 703 sdtx_push_event(ddev, &event.common); 704 705 /* Update device mode on base connection change. */ 706 if (in->command_id == SAM_EVENT_CID_DTX_CONNECTION) { 707 unsigned long delay; 708 709 delay = in->data[0] ? SDTX_DEVICE_MODE_DELAY_CONNECT : 0; 710 sdtx_update_device_mode(ddev, delay); 711 } 712 713out: 714 mutex_unlock(&ddev->write_lock); 715 return SSAM_NOTIF_HANDLED; 716} 717 718 719/* -- State update functions. ----------------------------------------------- */ 720 721static bool sdtx_device_mode_invalid(u8 mode, u8 base_state) 722{ 723 return ((base_state == SSAM_BAS_BASE_STATE_ATTACHED) && 724 (mode == SDTX_DEVICE_MODE_TABLET)) || 725 ((base_state == SSAM_BAS_BASE_STATE_DETACH_SUCCESS) && 726 (mode != SDTX_DEVICE_MODE_TABLET)); 727} 728 729static void sdtx_device_mode_workfn(struct work_struct *work) 730{ 731 struct sdtx_device *ddev = container_of(work, struct sdtx_device, mode_work.work); 732 struct sdtx_status_event event; 733 struct ssam_bas_base_info base; 734 int status, tablet; 735 u8 mode; 736 737 /* Get operation mode. */ 738 status = ssam_retry(ssam_bas_get_device_mode, ddev->ctrl, &mode); 739 if (status) { 740 dev_err(ddev->dev, "failed to get device mode: %d\n", status); 741 return; 742 } 743 744 /* Get base info. */ 745 status = ssam_retry(ssam_bas_get_base, ddev->ctrl, &base); 746 if (status) { 747 dev_err(ddev->dev, "failed to get base info: %d\n", status); 748 return; 749 } 750 751 /* 752 * In some cases (specifically when attaching the base), the device 753 * mode isn't updated right away. Thus we check if the device mode 754 * makes sense for the given base state and try again later if it 755 * doesn't. 756 */ 757 if (sdtx_device_mode_invalid(mode, base.state)) { 758 dev_dbg(ddev->dev, "device mode is invalid, trying again\n"); 759 sdtx_update_device_mode(ddev, SDTX_DEVICE_MODE_DELAY_RECHECK); 760 return; 761 } 762 763 mutex_lock(&ddev->write_lock); 764 clear_bit(SDTX_DEVICE_DIRTY_MODE_BIT, &ddev->flags); 765 766 /* Avoid sending duplicate device-mode events. */ 767 if (ddev->state.device_mode == mode) { 768 mutex_unlock(&ddev->write_lock); 769 return; 770 } 771 772 ddev->state.device_mode = mode; 773 774 event.e.length = sizeof(u16); 775 event.e.code = SDTX_EVENT_DEVICE_MODE; 776 event.v = mode; 777 778 sdtx_push_event(ddev, &event.e); 779 780 /* Send SW_TABLET_MODE event. */ 781 tablet = mode != SDTX_DEVICE_MODE_LAPTOP; 782 input_report_switch(ddev->mode_switch, SW_TABLET_MODE, tablet); 783 input_sync(ddev->mode_switch); 784 785 mutex_unlock(&ddev->write_lock); 786} 787 788static void sdtx_update_device_mode(struct sdtx_device *ddev, unsigned long delay) 789{ 790 schedule_delayed_work(&ddev->mode_work, delay); 791} 792 793/* Must be executed with ddev->write_lock held. */ 794static void __sdtx_device_state_update_base(struct sdtx_device *ddev, 795 struct ssam_bas_base_info info) 796{ 797 struct sdtx_base_info_event event; 798 799 lockdep_assert_held(&ddev->write_lock); 800 801 /* Prevent duplicate events. */ 802 if (ddev->state.base.state == info.state && 803 ddev->state.base.base_id == info.base_id) 804 return; 805 806 ddev->state.base = info; 807 808 event.e.length = sizeof(struct sdtx_base_info); 809 event.e.code = SDTX_EVENT_BASE_CONNECTION; 810 event.v.state = sdtx_translate_base_state(ddev, info.state); 811 event.v.base_id = SDTX_BASE_TYPE_SSH(info.base_id); 812 813 sdtx_push_event(ddev, &event.e); 814} 815 816/* Must be executed with ddev->write_lock held. */ 817static void __sdtx_device_state_update_mode(struct sdtx_device *ddev, u8 mode) 818{ 819 struct sdtx_status_event event; 820 int tablet; 821 822 /* 823 * Note: This function must be called after updating the base state 824 * via __sdtx_device_state_update_base(), as we rely on the updated 825 * base state value in the validity check below. 826 */ 827 828 lockdep_assert_held(&ddev->write_lock); 829 830 if (sdtx_device_mode_invalid(mode, ddev->state.base.state)) { 831 dev_dbg(ddev->dev, "device mode is invalid, trying again\n"); 832 sdtx_update_device_mode(ddev, SDTX_DEVICE_MODE_DELAY_RECHECK); 833 return; 834 } 835 836 /* Prevent duplicate events. */ 837 if (ddev->state.device_mode == mode) 838 return; 839 840 ddev->state.device_mode = mode; 841 842 /* Send event. */ 843 event.e.length = sizeof(u16); 844 event.e.code = SDTX_EVENT_DEVICE_MODE; 845 event.v = mode; 846 847 sdtx_push_event(ddev, &event.e); 848 849 /* Send SW_TABLET_MODE event. */ 850 tablet = mode != SDTX_DEVICE_MODE_LAPTOP; 851 input_report_switch(ddev->mode_switch, SW_TABLET_MODE, tablet); 852 input_sync(ddev->mode_switch); 853} 854 855/* Must be executed with ddev->write_lock held. */ 856static void __sdtx_device_state_update_latch(struct sdtx_device *ddev, u8 status) 857{ 858 struct sdtx_status_event event; 859 860 lockdep_assert_held(&ddev->write_lock); 861 862 /* Prevent duplicate events. */ 863 if (ddev->state.latch_status == status) 864 return; 865 866 ddev->state.latch_status = status; 867 868 event.e.length = sizeof(struct sdtx_base_info); 869 event.e.code = SDTX_EVENT_BASE_CONNECTION; 870 event.v = sdtx_translate_latch_status(ddev, status); 871 872 sdtx_push_event(ddev, &event.e); 873} 874 875static void sdtx_device_state_workfn(struct work_struct *work) 876{ 877 struct sdtx_device *ddev = container_of(work, struct sdtx_device, state_work.work); 878 struct ssam_bas_base_info base; 879 u8 mode, latch; 880 int status; 881 882 /* Mark everything as dirty. */ 883 set_bit(SDTX_DEVICE_DIRTY_BASE_BIT, &ddev->flags); 884 set_bit(SDTX_DEVICE_DIRTY_MODE_BIT, &ddev->flags); 885 set_bit(SDTX_DEVICE_DIRTY_LATCH_BIT, &ddev->flags); 886 887 /* 888 * Ensure that the state gets marked as dirty before continuing to 889 * query it. Necessary to ensure that clear_bit() calls in 890 * sdtx_notifier() and sdtx_device_mode_workfn() actually clear these 891 * bits if an event is received while updating the state here. 892 */ 893 smp_mb__after_atomic(); 894 895 status = ssam_retry(ssam_bas_get_base, ddev->ctrl, &base); 896 if (status) { 897 dev_err(ddev->dev, "failed to get base state: %d\n", status); 898 return; 899 } 900 901 status = ssam_retry(ssam_bas_get_device_mode, ddev->ctrl, &mode); 902 if (status) { 903 dev_err(ddev->dev, "failed to get device mode: %d\n", status); 904 return; 905 } 906 907 status = ssam_retry(ssam_bas_get_latch_status, ddev->ctrl, &latch); 908 if (status) { 909 dev_err(ddev->dev, "failed to get latch status: %d\n", status); 910 return; 911 } 912 913 mutex_lock(&ddev->write_lock); 914 915 /* 916 * If the respective dirty-bit has been cleared, an event has been 917 * received, updating this state. The queried state may thus be out of 918 * date. At this point, we can safely assume that the state provided 919 * by the event is either up to date, or we're about to receive 920 * another event updating it. 921 */ 922 923 if (test_and_clear_bit(SDTX_DEVICE_DIRTY_BASE_BIT, &ddev->flags)) 924 __sdtx_device_state_update_base(ddev, base); 925 926 if (test_and_clear_bit(SDTX_DEVICE_DIRTY_MODE_BIT, &ddev->flags)) 927 __sdtx_device_state_update_mode(ddev, mode); 928 929 if (test_and_clear_bit(SDTX_DEVICE_DIRTY_LATCH_BIT, &ddev->flags)) 930 __sdtx_device_state_update_latch(ddev, latch); 931 932 mutex_unlock(&ddev->write_lock); 933} 934 935static void sdtx_update_device_state(struct sdtx_device *ddev, unsigned long delay) 936{ 937 schedule_delayed_work(&ddev->state_work, delay); 938} 939 940 941/* -- Common device initialization. ----------------------------------------- */ 942 943static int sdtx_device_init(struct sdtx_device *ddev, struct device *dev, 944 struct ssam_controller *ctrl) 945{ 946 int status, tablet_mode; 947 948 /* Basic initialization. */ 949 kref_init(&ddev->kref); 950 init_rwsem(&ddev->lock); 951 ddev->dev = dev; 952 ddev->ctrl = ctrl; 953 954 ddev->mdev.minor = MISC_DYNAMIC_MINOR; 955 ddev->mdev.name = "surface_dtx"; 956 ddev->mdev.nodename = "surface/dtx"; 957 ddev->mdev.fops = &surface_dtx_fops; 958 959 ddev->notif.base.priority = 1; 960 ddev->notif.base.fn = sdtx_notifier; 961 ddev->notif.event.reg = SSAM_EVENT_REGISTRY_SAM; 962 ddev->notif.event.id.target_category = SSAM_SSH_TC_BAS; 963 ddev->notif.event.id.instance = 0; 964 ddev->notif.event.mask = SSAM_EVENT_MASK_NONE; 965 ddev->notif.event.flags = SSAM_EVENT_SEQUENCED; 966 967 init_waitqueue_head(&ddev->waitq); 968 mutex_init(&ddev->write_lock); 969 init_rwsem(&ddev->client_lock); 970 INIT_LIST_HEAD(&ddev->client_list); 971 972 INIT_DELAYED_WORK(&ddev->mode_work, sdtx_device_mode_workfn); 973 INIT_DELAYED_WORK(&ddev->state_work, sdtx_device_state_workfn); 974 975 /* 976 * Get current device state. We want to guarantee that events are only 977 * sent when state actually changes. Thus we cannot use special 978 * "uninitialized" values, as that would cause problems when manually 979 * querying the state in surface_dtx_pm_complete(). I.e. we would not 980 * be able to detect state changes there if no change event has been 981 * received between driver initialization and first device suspension. 982 * 983 * Note that we also need to do this before registering the event 984 * notifier, as that may access the state values. 985 */ 986 status = ssam_retry(ssam_bas_get_base, ddev->ctrl, &ddev->state.base); 987 if (status) 988 return status; 989 990 status = ssam_retry(ssam_bas_get_device_mode, ddev->ctrl, &ddev->state.device_mode); 991 if (status) 992 return status; 993 994 status = ssam_retry(ssam_bas_get_latch_status, ddev->ctrl, &ddev->state.latch_status); 995 if (status) 996 return status; 997 998 /* Set up tablet mode switch. */ 999 ddev->mode_switch = input_allocate_device(); 1000 if (!ddev->mode_switch) 1001 return -ENOMEM; 1002 1003 ddev->mode_switch->name = "Microsoft Surface DTX Device Mode Switch"; 1004 ddev->mode_switch->phys = "ssam/01:11:01:00:00/input0"; 1005 ddev->mode_switch->id.bustype = BUS_HOST; 1006 ddev->mode_switch->dev.parent = ddev->dev; 1007 1008 tablet_mode = (ddev->state.device_mode != SDTX_DEVICE_MODE_LAPTOP); 1009 input_set_capability(ddev->mode_switch, EV_SW, SW_TABLET_MODE); 1010 input_report_switch(ddev->mode_switch, SW_TABLET_MODE, tablet_mode); 1011 1012 status = input_register_device(ddev->mode_switch); 1013 if (status) { 1014 input_free_device(ddev->mode_switch); 1015 return status; 1016 } 1017 1018 /* Set up event notifier. */ 1019 status = ssam_notifier_register(ddev->ctrl, &ddev->notif); 1020 if (status) 1021 goto err_notif; 1022 1023 /* Register miscdevice. */ 1024 status = misc_register(&ddev->mdev); 1025 if (status) 1026 goto err_mdev; 1027 1028 /* 1029 * Update device state in case it has changed between getting the 1030 * initial mode and registering the event notifier. 1031 */ 1032 sdtx_update_device_state(ddev, 0); 1033 return 0; 1034 1035err_notif: 1036 ssam_notifier_unregister(ddev->ctrl, &ddev->notif); 1037 cancel_delayed_work_sync(&ddev->mode_work); 1038err_mdev: 1039 input_unregister_device(ddev->mode_switch); 1040 return status; 1041} 1042 1043static struct sdtx_device *sdtx_device_create(struct device *dev, struct ssam_controller *ctrl) 1044{ 1045 struct sdtx_device *ddev; 1046 int status; 1047 1048 ddev = kzalloc(sizeof(*ddev), GFP_KERNEL); 1049 if (!ddev) 1050 return ERR_PTR(-ENOMEM); 1051 1052 status = sdtx_device_init(ddev, dev, ctrl); 1053 if (status) { 1054 sdtx_device_put(ddev); 1055 return ERR_PTR(status); 1056 } 1057 1058 return ddev; 1059} 1060 1061static void sdtx_device_destroy(struct sdtx_device *ddev) 1062{ 1063 struct sdtx_client *client; 1064 1065 /* 1066 * Mark device as shut-down. Prevent new clients from being added and 1067 * new operations from being executed. 1068 */ 1069 set_bit(SDTX_DEVICE_SHUTDOWN_BIT, &ddev->flags); 1070 1071 /* Disable notifiers, prevent new events from arriving. */ 1072 ssam_notifier_unregister(ddev->ctrl, &ddev->notif); 1073 1074 /* Stop mode_work, prevent access to mode_switch. */ 1075 cancel_delayed_work_sync(&ddev->mode_work); 1076 1077 /* Stop state_work. */ 1078 cancel_delayed_work_sync(&ddev->state_work); 1079 1080 /* With mode_work canceled, we can unregister the mode_switch. */ 1081 input_unregister_device(ddev->mode_switch); 1082 1083 /* Wake up async clients. */ 1084 down_write(&ddev->client_lock); 1085 list_for_each_entry(client, &ddev->client_list, node) { 1086 kill_fasync(&client->fasync, SIGIO, POLL_HUP); 1087 } 1088 up_write(&ddev->client_lock); 1089 1090 /* Wake up blocking clients. */ 1091 wake_up_interruptible(&ddev->waitq); 1092 1093 /* 1094 * Wait for clients to finish their current operation. After this, the 1095 * controller and device references are guaranteed to be no longer in 1096 * use. 1097 */ 1098 down_write(&ddev->lock); 1099 ddev->dev = NULL; 1100 ddev->ctrl = NULL; 1101 up_write(&ddev->lock); 1102 1103 /* Finally remove the misc-device. */ 1104 misc_deregister(&ddev->mdev); 1105 1106 /* 1107 * We're now guaranteed that sdtx_device_open() won't be called any 1108 * more, so we can now drop out reference. 1109 */ 1110 sdtx_device_put(ddev); 1111} 1112 1113 1114/* -- PM ops. --------------------------------------------------------------- */ 1115 1116#ifdef CONFIG_PM_SLEEP 1117 1118static void surface_dtx_pm_complete(struct device *dev) 1119{ 1120 struct sdtx_device *ddev = dev_get_drvdata(dev); 1121 1122 /* 1123 * Normally, the EC will store events while suspended (i.e. in 1124 * display-off state) and release them when resumed (i.e. transitioned 1125 * to display-on state). During hibernation, however, the EC will be 1126 * shut down and does not store events. Furthermore, events might be 1127 * dropped during prolonged suspension (it is currently unknown how 1128 * big this event buffer is and how it behaves on overruns). 1129 * 1130 * To prevent any problems, we update the device state here. We do 1131 * this delayed to ensure that any events sent by the EC directly 1132 * after resuming will be handled first. The delay below has been 1133 * chosen (experimentally), so that there should be ample time for 1134 * these events to be handled, before we check and, if necessary, 1135 * update the state. 1136 */ 1137 sdtx_update_device_state(ddev, msecs_to_jiffies(1000)); 1138} 1139 1140static const struct dev_pm_ops surface_dtx_pm_ops = { 1141 .complete = surface_dtx_pm_complete, 1142}; 1143 1144#else /* CONFIG_PM_SLEEP */ 1145 1146static const struct dev_pm_ops surface_dtx_pm_ops = {}; 1147 1148#endif /* CONFIG_PM_SLEEP */ 1149 1150 1151/* -- Platform driver. ------------------------------------------------------ */ 1152 1153static int surface_dtx_platform_probe(struct platform_device *pdev) 1154{ 1155 struct ssam_controller *ctrl; 1156 struct sdtx_device *ddev; 1157 1158 /* Link to EC. */ 1159 ctrl = ssam_client_bind(&pdev->dev); 1160 if (IS_ERR(ctrl)) 1161 return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl); 1162 1163 ddev = sdtx_device_create(&pdev->dev, ctrl); 1164 if (IS_ERR(ddev)) 1165 return PTR_ERR(ddev); 1166 1167 platform_set_drvdata(pdev, ddev); 1168 return 0; 1169} 1170 1171static int surface_dtx_platform_remove(struct platform_device *pdev) 1172{ 1173 sdtx_device_destroy(platform_get_drvdata(pdev)); 1174 return 0; 1175} 1176 1177static const struct acpi_device_id surface_dtx_acpi_match[] = { 1178 { "MSHW0133", 0 }, 1179 { }, 1180}; 1181MODULE_DEVICE_TABLE(acpi, surface_dtx_acpi_match); 1182 1183static struct platform_driver surface_dtx_platform_driver = { 1184 .probe = surface_dtx_platform_probe, 1185 .remove = surface_dtx_platform_remove, 1186 .driver = { 1187 .name = "surface_dtx_pltf", 1188 .acpi_match_table = surface_dtx_acpi_match, 1189 .pm = &surface_dtx_pm_ops, 1190 .probe_type = PROBE_PREFER_ASYNCHRONOUS, 1191 }, 1192}; 1193 1194 1195/* -- SSAM device driver. --------------------------------------------------- */ 1196 1197#ifdef CONFIG_SURFACE_AGGREGATOR_BUS 1198 1199static int surface_dtx_ssam_probe(struct ssam_device *sdev) 1200{ 1201 struct sdtx_device *ddev; 1202 1203 ddev = sdtx_device_create(&sdev->dev, sdev->ctrl); 1204 if (IS_ERR(ddev)) 1205 return PTR_ERR(ddev); 1206 1207 ssam_device_set_drvdata(sdev, ddev); 1208 return 0; 1209} 1210 1211static void surface_dtx_ssam_remove(struct ssam_device *sdev) 1212{ 1213 sdtx_device_destroy(ssam_device_get_drvdata(sdev)); 1214} 1215 1216static const struct ssam_device_id surface_dtx_ssam_match[] = { 1217 { SSAM_SDEV(BAS, SAM, 0x00, 0x00) }, 1218 { }, 1219}; 1220MODULE_DEVICE_TABLE(ssam, surface_dtx_ssam_match); 1221 1222static struct ssam_device_driver surface_dtx_ssam_driver = { 1223 .probe = surface_dtx_ssam_probe, 1224 .remove = surface_dtx_ssam_remove, 1225 .match_table = surface_dtx_ssam_match, 1226 .driver = { 1227 .name = "surface_dtx", 1228 .pm = &surface_dtx_pm_ops, 1229 .probe_type = PROBE_PREFER_ASYNCHRONOUS, 1230 }, 1231}; 1232 1233static int ssam_dtx_driver_register(void) 1234{ 1235 return ssam_device_driver_register(&surface_dtx_ssam_driver); 1236} 1237 1238static void ssam_dtx_driver_unregister(void) 1239{ 1240 ssam_device_driver_unregister(&surface_dtx_ssam_driver); 1241} 1242 1243#else /* CONFIG_SURFACE_AGGREGATOR_BUS */ 1244 1245static int ssam_dtx_driver_register(void) 1246{ 1247 return 0; 1248} 1249 1250static void ssam_dtx_driver_unregister(void) 1251{ 1252} 1253 1254#endif /* CONFIG_SURFACE_AGGREGATOR_BUS */ 1255 1256 1257/* -- Module setup. --------------------------------------------------------- */ 1258 1259static int __init surface_dtx_init(void) 1260{ 1261 int status; 1262 1263 status = ssam_dtx_driver_register(); 1264 if (status) 1265 return status; 1266 1267 status = platform_driver_register(&surface_dtx_platform_driver); 1268 if (status) 1269 ssam_dtx_driver_unregister(); 1270 1271 return status; 1272} 1273module_init(surface_dtx_init); 1274 1275static void __exit surface_dtx_exit(void) 1276{ 1277 platform_driver_unregister(&surface_dtx_platform_driver); 1278 ssam_dtx_driver_unregister(); 1279} 1280module_exit(surface_dtx_exit); 1281 1282MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>"); 1283MODULE_DESCRIPTION("Detachment-system driver for Surface System Aggregator Module"); 1284MODULE_LICENSE("GPL"); 1285