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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 <[email protected]>
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_obj(*client);
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};
559
560
561/* -- Event handling/forwarding. -------------------------------------------- */
562
563/*
564 * The device operation mode is not immediately updated on the EC when the
565 * base has been connected, i.e. querying the device mode inside the
566 * connection event callback yields an outdated value. Thus, we can only
567 * determine the new tablet-mode switch and device mode values after some
568 * time.
569 *
570 * These delays have been chosen by experimenting. We first delay on connect
571 * events, then check and validate the device mode against the base state and
572 * if invalid delay again by the "recheck" delay.
573 */
574#define SDTX_DEVICE_MODE_DELAY_CONNECT msecs_to_jiffies(100)
575#define SDTX_DEVICE_MODE_DELAY_RECHECK msecs_to_jiffies(100)
576
577struct sdtx_status_event {
578 struct sdtx_event e;
579 __u16 v;
580} __packed;
581
582struct sdtx_base_info_event {
583 struct sdtx_event e;
584 struct sdtx_base_info v;
585} __packed;
586
587union sdtx_generic_event {
588 struct sdtx_event common;
589 struct sdtx_status_event status;
590 struct sdtx_base_info_event base;
591};
592
593static void sdtx_update_device_mode(struct sdtx_device *ddev, unsigned long delay);
594
595/* Must be executed with ddev->write_lock held. */
596static void sdtx_push_event(struct sdtx_device *ddev, struct sdtx_event *evt)
597{
598 const size_t len = sizeof(struct sdtx_event) + evt->length;
599 struct sdtx_client *client;
600
601 lockdep_assert_held(&ddev->write_lock);
602
603 down_read(&ddev->client_lock);
604 list_for_each_entry(client, &ddev->client_list, node) {
605 if (!test_bit(SDTX_CLIENT_EVENTS_ENABLED_BIT, &client->flags))
606 continue;
607
608 if (likely(kfifo_avail(&client->buffer) >= len))
609 kfifo_in(&client->buffer, (const u8 *)evt, len);
610 else
611 dev_warn(ddev->dev, "event buffer overrun\n");
612
613 kill_fasync(&client->fasync, SIGIO, POLL_IN);
614 }
615 up_read(&ddev->client_lock);
616
617 wake_up_interruptible(&ddev->waitq);
618}
619
620static u32 sdtx_notifier(struct ssam_event_notifier *nf, const struct ssam_event *in)
621{
622 struct sdtx_device *ddev = container_of(nf, struct sdtx_device, notif);
623 union sdtx_generic_event event;
624 size_t len;
625
626 /* Validate event payload length. */
627 switch (in->command_id) {
628 case SAM_EVENT_CID_DTX_CONNECTION:
629 len = 2 * sizeof(u8);
630 break;
631
632 case SAM_EVENT_CID_DTX_REQUEST:
633 len = 0;
634 break;
635
636 case SAM_EVENT_CID_DTX_CANCEL:
637 len = sizeof(u8);
638 break;
639
640 case SAM_EVENT_CID_DTX_LATCH_STATUS:
641 len = sizeof(u8);
642 break;
643
644 default:
645 return 0;
646 }
647
648 if (in->length != len) {
649 dev_err(ddev->dev,
650 "unexpected payload size for event %#04x: got %u, expected %zu\n",
651 in->command_id, in->length, len);
652 return 0;
653 }
654
655 mutex_lock(&ddev->write_lock);
656
657 /* Translate event. */
658 switch (in->command_id) {
659 case SAM_EVENT_CID_DTX_CONNECTION:
660 clear_bit(SDTX_DEVICE_DIRTY_BASE_BIT, &ddev->flags);
661
662 /* If state has not changed: do not send new event. */
663 if (ddev->state.base.state == in->data[0] &&
664 ddev->state.base.base_id == in->data[1])
665 goto out;
666
667 ddev->state.base.state = in->data[0];
668 ddev->state.base.base_id = in->data[1];
669
670 event.base.e.length = sizeof(struct sdtx_base_info);
671 event.base.e.code = SDTX_EVENT_BASE_CONNECTION;
672 event.base.v.state = sdtx_translate_base_state(ddev, in->data[0]);
673 event.base.v.base_id = SDTX_BASE_TYPE_SSH(in->data[1]);
674 break;
675
676 case SAM_EVENT_CID_DTX_REQUEST:
677 event.common.code = SDTX_EVENT_REQUEST;
678 event.common.length = 0;
679 break;
680
681 case SAM_EVENT_CID_DTX_CANCEL:
682 event.status.e.length = sizeof(u16);
683 event.status.e.code = SDTX_EVENT_CANCEL;
684 event.status.v = sdtx_translate_cancel_reason(ddev, in->data[0]);
685 break;
686
687 case SAM_EVENT_CID_DTX_LATCH_STATUS:
688 clear_bit(SDTX_DEVICE_DIRTY_LATCH_BIT, &ddev->flags);
689
690 /* If state has not changed: do not send new event. */
691 if (ddev->state.latch_status == in->data[0])
692 goto out;
693
694 ddev->state.latch_status = in->data[0];
695
696 event.status.e.length = sizeof(u16);
697 event.status.e.code = SDTX_EVENT_LATCH_STATUS;
698 event.status.v = sdtx_translate_latch_status(ddev, in->data[0]);
699 break;
700 }
701
702 sdtx_push_event(ddev, &event.common);
703
704 /* Update device mode on base connection change. */
705 if (in->command_id == SAM_EVENT_CID_DTX_CONNECTION) {
706 unsigned long delay;
707
708 delay = in->data[0] ? SDTX_DEVICE_MODE_DELAY_CONNECT : 0;
709 sdtx_update_device_mode(ddev, delay);
710 }
711
712out:
713 mutex_unlock(&ddev->write_lock);
714 return SSAM_NOTIF_HANDLED;
715}
716
717
718/* -- State update functions. ----------------------------------------------- */
719
720static bool sdtx_device_mode_invalid(u8 mode, u8 base_state)
721{
722 return ((base_state == SSAM_BAS_BASE_STATE_ATTACHED) &&
723 (mode == SDTX_DEVICE_MODE_TABLET)) ||
724 ((base_state == SSAM_BAS_BASE_STATE_DETACH_SUCCESS) &&
725 (mode != SDTX_DEVICE_MODE_TABLET));
726}
727
728static void sdtx_device_mode_workfn(struct work_struct *work)
729{
730 struct sdtx_device *ddev = container_of(work, struct sdtx_device, mode_work.work);
731 struct sdtx_status_event event;
732 struct ssam_bas_base_info base;
733 int status, tablet;
734 u8 mode;
735
736 /* Get operation mode. */
737 status = ssam_retry(ssam_bas_get_device_mode, ddev->ctrl, &mode);
738 if (status) {
739 dev_err(ddev->dev, "failed to get device mode: %d\n", status);
740 return;
741 }
742
743 /* Get base info. */
744 status = ssam_retry(ssam_bas_get_base, ddev->ctrl, &base);
745 if (status) {
746 dev_err(ddev->dev, "failed to get base info: %d\n", status);
747 return;
748 }
749
750 /*
751 * In some cases (specifically when attaching the base), the device
752 * mode isn't updated right away. Thus we check if the device mode
753 * makes sense for the given base state and try again later if it
754 * doesn't.
755 */
756 if (sdtx_device_mode_invalid(mode, base.state)) {
757 dev_dbg(ddev->dev, "device mode is invalid, trying again\n");
758 sdtx_update_device_mode(ddev, SDTX_DEVICE_MODE_DELAY_RECHECK);
759 return;
760 }
761
762 mutex_lock(&ddev->write_lock);
763 clear_bit(SDTX_DEVICE_DIRTY_MODE_BIT, &ddev->flags);
764
765 /* Avoid sending duplicate device-mode events. */
766 if (ddev->state.device_mode == mode) {
767 mutex_unlock(&ddev->write_lock);
768 return;
769 }
770
771 ddev->state.device_mode = mode;
772
773 event.e.length = sizeof(u16);
774 event.e.code = SDTX_EVENT_DEVICE_MODE;
775 event.v = mode;
776
777 sdtx_push_event(ddev, &event.e);
778
779 /* Send SW_TABLET_MODE event. */
780 tablet = mode != SDTX_DEVICE_MODE_LAPTOP;
781 input_report_switch(ddev->mode_switch, SW_TABLET_MODE, tablet);
782 input_sync(ddev->mode_switch);
783
784 mutex_unlock(&ddev->write_lock);
785}
786
787static void sdtx_update_device_mode(struct sdtx_device *ddev, unsigned long delay)
788{
789 schedule_delayed_work(&ddev->mode_work, delay);
790}
791
792/* Must be executed with ddev->write_lock held. */
793static void __sdtx_device_state_update_base(struct sdtx_device *ddev,
794 struct ssam_bas_base_info info)
795{
796 struct sdtx_base_info_event event;
797
798 lockdep_assert_held(&ddev->write_lock);
799
800 /* Prevent duplicate events. */
801 if (ddev->state.base.state == info.state &&
802 ddev->state.base.base_id == info.base_id)
803 return;
804
805 ddev->state.base = info;
806
807 event.e.length = sizeof(struct sdtx_base_info);
808 event.e.code = SDTX_EVENT_BASE_CONNECTION;
809 event.v.state = sdtx_translate_base_state(ddev, info.state);
810 event.v.base_id = SDTX_BASE_TYPE_SSH(info.base_id);
811
812 sdtx_push_event(ddev, &event.e);
813}
814
815/* Must be executed with ddev->write_lock held. */
816static void __sdtx_device_state_update_mode(struct sdtx_device *ddev, u8 mode)
817{
818 struct sdtx_status_event event;
819 int tablet;
820
821 /*
822 * Note: This function must be called after updating the base state
823 * via __sdtx_device_state_update_base(), as we rely on the updated
824 * base state value in the validity check below.
825 */
826
827 lockdep_assert_held(&ddev->write_lock);
828
829 if (sdtx_device_mode_invalid(mode, ddev->state.base.state)) {
830 dev_dbg(ddev->dev, "device mode is invalid, trying again\n");
831 sdtx_update_device_mode(ddev, SDTX_DEVICE_MODE_DELAY_RECHECK);
832 return;
833 }
834
835 /* Prevent duplicate events. */
836 if (ddev->state.device_mode == mode)
837 return;
838
839 ddev->state.device_mode = mode;
840
841 /* Send event. */
842 event.e.length = sizeof(u16);
843 event.e.code = SDTX_EVENT_DEVICE_MODE;
844 event.v = mode;
845
846 sdtx_push_event(ddev, &event.e);
847
848 /* Send SW_TABLET_MODE event. */
849 tablet = mode != SDTX_DEVICE_MODE_LAPTOP;
850 input_report_switch(ddev->mode_switch, SW_TABLET_MODE, tablet);
851 input_sync(ddev->mode_switch);
852}
853
854/* Must be executed with ddev->write_lock held. */
855static void __sdtx_device_state_update_latch(struct sdtx_device *ddev, u8 status)
856{
857 struct sdtx_status_event event;
858
859 lockdep_assert_held(&ddev->write_lock);
860
861 /* Prevent duplicate events. */
862 if (ddev->state.latch_status == status)
863 return;
864
865 ddev->state.latch_status = status;
866
867 event.e.length = sizeof(struct sdtx_base_info);
868 event.e.code = SDTX_EVENT_BASE_CONNECTION;
869 event.v = sdtx_translate_latch_status(ddev, status);
870
871 sdtx_push_event(ddev, &event.e);
872}
873
874static void sdtx_device_state_workfn(struct work_struct *work)
875{
876 struct sdtx_device *ddev = container_of(work, struct sdtx_device, state_work.work);
877 struct ssam_bas_base_info base;
878 u8 mode, latch;
879 int status;
880
881 /* Mark everything as dirty. */
882 set_bit(SDTX_DEVICE_DIRTY_BASE_BIT, &ddev->flags);
883 set_bit(SDTX_DEVICE_DIRTY_MODE_BIT, &ddev->flags);
884 set_bit(SDTX_DEVICE_DIRTY_LATCH_BIT, &ddev->flags);
885
886 /*
887 * Ensure that the state gets marked as dirty before continuing to
888 * query it. Necessary to ensure that clear_bit() calls in
889 * sdtx_notifier() and sdtx_device_mode_workfn() actually clear these
890 * bits if an event is received while updating the state here.
891 */
892 smp_mb__after_atomic();
893
894 status = ssam_retry(ssam_bas_get_base, ddev->ctrl, &base);
895 if (status) {
896 dev_err(ddev->dev, "failed to get base state: %d\n", status);
897 return;
898 }
899
900 status = ssam_retry(ssam_bas_get_device_mode, ddev->ctrl, &mode);
901 if (status) {
902 dev_err(ddev->dev, "failed to get device mode: %d\n", status);
903 return;
904 }
905
906 status = ssam_retry(ssam_bas_get_latch_status, ddev->ctrl, &latch);
907 if (status) {
908 dev_err(ddev->dev, "failed to get latch status: %d\n", status);
909 return;
910 }
911
912 mutex_lock(&ddev->write_lock);
913
914 /*
915 * If the respective dirty-bit has been cleared, an event has been
916 * received, updating this state. The queried state may thus be out of
917 * date. At this point, we can safely assume that the state provided
918 * by the event is either up to date, or we're about to receive
919 * another event updating it.
920 */
921
922 if (test_and_clear_bit(SDTX_DEVICE_DIRTY_BASE_BIT, &ddev->flags))
923 __sdtx_device_state_update_base(ddev, base);
924
925 if (test_and_clear_bit(SDTX_DEVICE_DIRTY_MODE_BIT, &ddev->flags))
926 __sdtx_device_state_update_mode(ddev, mode);
927
928 if (test_and_clear_bit(SDTX_DEVICE_DIRTY_LATCH_BIT, &ddev->flags))
929 __sdtx_device_state_update_latch(ddev, latch);
930
931 mutex_unlock(&ddev->write_lock);
932}
933
934static void sdtx_update_device_state(struct sdtx_device *ddev, unsigned long delay)
935{
936 schedule_delayed_work(&ddev->state_work, delay);
937}
938
939
940/* -- Common device initialization. ----------------------------------------- */
941
942static int sdtx_device_init(struct sdtx_device *ddev, struct device *dev,
943 struct ssam_controller *ctrl)
944{
945 int status, tablet_mode;
946
947 /* Basic initialization. */
948 kref_init(&ddev->kref);
949 init_rwsem(&ddev->lock);
950 ddev->dev = dev;
951 ddev->ctrl = ctrl;
952
953 ddev->mdev.minor = MISC_DYNAMIC_MINOR;
954 ddev->mdev.name = "surface_dtx";
955 ddev->mdev.nodename = "surface/dtx";
956 ddev->mdev.fops = &surface_dtx_fops;
957
958 ddev->notif.base.priority = 1;
959 ddev->notif.base.fn = sdtx_notifier;
960 ddev->notif.event.reg = SSAM_EVENT_REGISTRY_SAM;
961 ddev->notif.event.id.target_category = SSAM_SSH_TC_BAS;
962 ddev->notif.event.id.instance = 0;
963 ddev->notif.event.mask = SSAM_EVENT_MASK_NONE;
964 ddev->notif.event.flags = SSAM_EVENT_SEQUENCED;
965
966 init_waitqueue_head(&ddev->waitq);
967 mutex_init(&ddev->write_lock);
968 init_rwsem(&ddev->client_lock);
969 INIT_LIST_HEAD(&ddev->client_list);
970
971 INIT_DELAYED_WORK(&ddev->mode_work, sdtx_device_mode_workfn);
972 INIT_DELAYED_WORK(&ddev->state_work, sdtx_device_state_workfn);
973
974 /*
975 * Get current device state. We want to guarantee that events are only
976 * sent when state actually changes. Thus we cannot use special
977 * "uninitialized" values, as that would cause problems when manually
978 * querying the state in surface_dtx_pm_complete(). I.e. we would not
979 * be able to detect state changes there if no change event has been
980 * received between driver initialization and first device suspension.
981 *
982 * Note that we also need to do this before registering the event
983 * notifier, as that may access the state values.
984 */
985 status = ssam_retry(ssam_bas_get_base, ddev->ctrl, &ddev->state.base);
986 if (status)
987 return status;
988
989 status = ssam_retry(ssam_bas_get_device_mode, ddev->ctrl, &ddev->state.device_mode);
990 if (status)
991 return status;
992
993 status = ssam_retry(ssam_bas_get_latch_status, ddev->ctrl, &ddev->state.latch_status);
994 if (status)
995 return status;
996
997 /* Set up tablet mode switch. */
998 ddev->mode_switch = input_allocate_device();
999 if (!ddev->mode_switch)
1000 return -ENOMEM;
1001
1002 ddev->mode_switch->name = "Microsoft Surface DTX Device Mode Switch";
1003 ddev->mode_switch->phys = "ssam/01:11:01:00:00/input0";
1004 ddev->mode_switch->id.bustype = BUS_HOST;
1005 ddev->mode_switch->dev.parent = ddev->dev;
1006
1007 tablet_mode = (ddev->state.device_mode != SDTX_DEVICE_MODE_LAPTOP);
1008 input_set_capability(ddev->mode_switch, EV_SW, SW_TABLET_MODE);
1009 input_report_switch(ddev->mode_switch, SW_TABLET_MODE, tablet_mode);
1010
1011 status = input_register_device(ddev->mode_switch);
1012 if (status) {
1013 input_free_device(ddev->mode_switch);
1014 return status;
1015 }
1016
1017 /* Set up event notifier. */
1018 status = ssam_notifier_register(ddev->ctrl, &ddev->notif);
1019 if (status)
1020 goto err_notif;
1021
1022 /* Register miscdevice. */
1023 status = misc_register(&ddev->mdev);
1024 if (status)
1025 goto err_mdev;
1026
1027 /*
1028 * Update device state in case it has changed between getting the
1029 * initial mode and registering the event notifier.
1030 */
1031 sdtx_update_device_state(ddev, 0);
1032 return 0;
1033
1034err_notif:
1035 ssam_notifier_unregister(ddev->ctrl, &ddev->notif);
1036 cancel_delayed_work_sync(&ddev->mode_work);
1037err_mdev:
1038 input_unregister_device(ddev->mode_switch);
1039 return status;
1040}
1041
1042static struct sdtx_device *sdtx_device_create(struct device *dev, struct ssam_controller *ctrl)
1043{
1044 struct sdtx_device *ddev;
1045 int status;
1046
1047 ddev = kzalloc_obj(*ddev);
1048 if (!ddev)
1049 return ERR_PTR(-ENOMEM);
1050
1051 status = sdtx_device_init(ddev, dev, ctrl);
1052 if (status) {
1053 sdtx_device_put(ddev);
1054 return ERR_PTR(status);
1055 }
1056
1057 return ddev;
1058}
1059
1060static void sdtx_device_destroy(struct sdtx_device *ddev)
1061{
1062 struct sdtx_client *client;
1063
1064 /*
1065 * Mark device as shut-down. Prevent new clients from being added and
1066 * new operations from being executed.
1067 */
1068 set_bit(SDTX_DEVICE_SHUTDOWN_BIT, &ddev->flags);
1069
1070 /* Disable notifiers, prevent new events from arriving. */
1071 ssam_notifier_unregister(ddev->ctrl, &ddev->notif);
1072
1073 /* Stop mode_work, prevent access to mode_switch. */
1074 cancel_delayed_work_sync(&ddev->mode_work);
1075
1076 /* Stop state_work. */
1077 cancel_delayed_work_sync(&ddev->state_work);
1078
1079 /* With mode_work canceled, we can unregister the mode_switch. */
1080 input_unregister_device(ddev->mode_switch);
1081
1082 /* Wake up async clients. */
1083 down_write(&ddev->client_lock);
1084 list_for_each_entry(client, &ddev->client_list, node) {
1085 kill_fasync(&client->fasync, SIGIO, POLL_HUP);
1086 }
1087 up_write(&ddev->client_lock);
1088
1089 /* Wake up blocking clients. */
1090 wake_up_interruptible(&ddev->waitq);
1091
1092 /*
1093 * Wait for clients to finish their current operation. After this, the
1094 * controller and device references are guaranteed to be no longer in
1095 * use.
1096 */
1097 down_write(&ddev->lock);
1098 ddev->dev = NULL;
1099 ddev->ctrl = NULL;
1100 up_write(&ddev->lock);
1101
1102 /* Finally remove the misc-device. */
1103 misc_deregister(&ddev->mdev);
1104
1105 /*
1106 * We're now guaranteed that sdtx_device_open() won't be called any
1107 * more, so we can now drop out reference.
1108 */
1109 sdtx_device_put(ddev);
1110}
1111
1112
1113/* -- PM ops. --------------------------------------------------------------- */
1114
1115#ifdef CONFIG_PM_SLEEP
1116
1117static void surface_dtx_pm_complete(struct device *dev)
1118{
1119 struct sdtx_device *ddev = dev_get_drvdata(dev);
1120
1121 /*
1122 * Normally, the EC will store events while suspended (i.e. in
1123 * display-off state) and release them when resumed (i.e. transitioned
1124 * to display-on state). During hibernation, however, the EC will be
1125 * shut down and does not store events. Furthermore, events might be
1126 * dropped during prolonged suspension (it is currently unknown how
1127 * big this event buffer is and how it behaves on overruns).
1128 *
1129 * To prevent any problems, we update the device state here. We do
1130 * this delayed to ensure that any events sent by the EC directly
1131 * after resuming will be handled first. The delay below has been
1132 * chosen (experimentally), so that there should be ample time for
1133 * these events to be handled, before we check and, if necessary,
1134 * update the state.
1135 */
1136 sdtx_update_device_state(ddev, msecs_to_jiffies(1000));
1137}
1138
1139static const struct dev_pm_ops surface_dtx_pm_ops = {
1140 .complete = surface_dtx_pm_complete,
1141};
1142
1143#else /* CONFIG_PM_SLEEP */
1144
1145static const struct dev_pm_ops surface_dtx_pm_ops = {};
1146
1147#endif /* CONFIG_PM_SLEEP */
1148
1149
1150/* -- Platform driver. ------------------------------------------------------ */
1151
1152static int surface_dtx_platform_probe(struct platform_device *pdev)
1153{
1154 struct ssam_controller *ctrl;
1155 struct sdtx_device *ddev;
1156
1157 /* Link to EC. */
1158 ctrl = ssam_client_bind(&pdev->dev);
1159 if (IS_ERR(ctrl))
1160 return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl);
1161
1162 ddev = sdtx_device_create(&pdev->dev, ctrl);
1163 if (IS_ERR(ddev))
1164 return PTR_ERR(ddev);
1165
1166 platform_set_drvdata(pdev, ddev);
1167 return 0;
1168}
1169
1170static void surface_dtx_platform_remove(struct platform_device *pdev)
1171{
1172 sdtx_device_destroy(platform_get_drvdata(pdev));
1173}
1174
1175static const struct acpi_device_id surface_dtx_acpi_match[] = {
1176 { "MSHW0133", 0 },
1177 { },
1178};
1179MODULE_DEVICE_TABLE(acpi, surface_dtx_acpi_match);
1180
1181static struct platform_driver surface_dtx_platform_driver = {
1182 .probe = surface_dtx_platform_probe,
1183 .remove = surface_dtx_platform_remove,
1184 .driver = {
1185 .name = "surface_dtx_pltf",
1186 .acpi_match_table = surface_dtx_acpi_match,
1187 .pm = &surface_dtx_pm_ops,
1188 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
1189 },
1190};
1191
1192
1193/* -- SSAM device driver. --------------------------------------------------- */
1194
1195#ifdef CONFIG_SURFACE_AGGREGATOR_BUS
1196
1197static int surface_dtx_ssam_probe(struct ssam_device *sdev)
1198{
1199 struct sdtx_device *ddev;
1200
1201 ddev = sdtx_device_create(&sdev->dev, sdev->ctrl);
1202 if (IS_ERR(ddev))
1203 return PTR_ERR(ddev);
1204
1205 ssam_device_set_drvdata(sdev, ddev);
1206 return 0;
1207}
1208
1209static void surface_dtx_ssam_remove(struct ssam_device *sdev)
1210{
1211 sdtx_device_destroy(ssam_device_get_drvdata(sdev));
1212}
1213
1214static const struct ssam_device_id surface_dtx_ssam_match[] = {
1215 { SSAM_SDEV(BAS, SAM, 0x00, 0x00) },
1216 { },
1217};
1218MODULE_DEVICE_TABLE(ssam, surface_dtx_ssam_match);
1219
1220static struct ssam_device_driver surface_dtx_ssam_driver = {
1221 .probe = surface_dtx_ssam_probe,
1222 .remove = surface_dtx_ssam_remove,
1223 .match_table = surface_dtx_ssam_match,
1224 .driver = {
1225 .name = "surface_dtx",
1226 .pm = &surface_dtx_pm_ops,
1227 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
1228 },
1229};
1230
1231static int ssam_dtx_driver_register(void)
1232{
1233 return ssam_device_driver_register(&surface_dtx_ssam_driver);
1234}
1235
1236static void ssam_dtx_driver_unregister(void)
1237{
1238 ssam_device_driver_unregister(&surface_dtx_ssam_driver);
1239}
1240
1241#else /* CONFIG_SURFACE_AGGREGATOR_BUS */
1242
1243static int ssam_dtx_driver_register(void)
1244{
1245 return 0;
1246}
1247
1248static void ssam_dtx_driver_unregister(void)
1249{
1250}
1251
1252#endif /* CONFIG_SURFACE_AGGREGATOR_BUS */
1253
1254
1255/* -- Module setup. --------------------------------------------------------- */
1256
1257static int __init surface_dtx_init(void)
1258{
1259 int status;
1260
1261 status = ssam_dtx_driver_register();
1262 if (status)
1263 return status;
1264
1265 status = platform_driver_register(&surface_dtx_platform_driver);
1266 if (status)
1267 ssam_dtx_driver_unregister();
1268
1269 return status;
1270}
1271module_init(surface_dtx_init);
1272
1273static void __exit surface_dtx_exit(void)
1274{
1275 platform_driver_unregister(&surface_dtx_platform_driver);
1276 ssam_dtx_driver_unregister();
1277}
1278module_exit(surface_dtx_exit);
1279
1280MODULE_AUTHOR("Maximilian Luz <[email protected]>");
1281MODULE_DESCRIPTION("Detachment-system driver for Surface System Aggregator Module");
1282MODULE_LICENSE("GPL");