1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Surface System Aggregator Module (SSAM) tablet mode switch driver.
4  *
5  * Copyright (C) 2022 Maximilian Luz <luzmaximilian@gmail.com>
6  */
7 
8 #include <asm/unaligned.h>
9 #include <linux/input.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/types.h>
13 #include <linux/workqueue.h>
14 
15 #include <linux/surface_aggregator/controller.h>
16 #include <linux/surface_aggregator/device.h>
17 
18 
19 /* -- SSAM generic tablet switch driver framework. -------------------------- */
20 
21 struct ssam_tablet_sw;
22 
23 struct ssam_tablet_sw_state {
24 	u32 source;
25 	u32 state;
26 };
27 
28 struct ssam_tablet_sw_ops {
29 	int (*get_state)(struct ssam_tablet_sw *sw, struct ssam_tablet_sw_state *state);
30 	const char *(*state_name)(struct ssam_tablet_sw *sw,
31 				  const struct ssam_tablet_sw_state *state);
32 	bool (*state_is_tablet_mode)(struct ssam_tablet_sw *sw,
33 				     const struct ssam_tablet_sw_state *state);
34 };
35 
36 struct ssam_tablet_sw {
37 	struct ssam_device *sdev;
38 
39 	struct ssam_tablet_sw_state state;
40 	struct work_struct update_work;
41 	struct input_dev *mode_switch;
42 
43 	struct ssam_tablet_sw_ops ops;
44 	struct ssam_event_notifier notif;
45 };
46 
47 struct ssam_tablet_sw_desc {
48 	struct {
49 		const char *name;
50 		const char *phys;
51 	} dev;
52 
53 	struct {
54 		u32 (*notify)(struct ssam_event_notifier *nf, const struct ssam_event *event);
55 		int (*get_state)(struct ssam_tablet_sw *sw, struct ssam_tablet_sw_state *state);
56 		const char *(*state_name)(struct ssam_tablet_sw *sw,
57 					  const struct ssam_tablet_sw_state *state);
58 		bool (*state_is_tablet_mode)(struct ssam_tablet_sw *sw,
59 					     const struct ssam_tablet_sw_state *state);
60 	} ops;
61 
62 	struct {
63 		struct ssam_event_registry reg;
64 		struct ssam_event_id id;
65 		enum ssam_event_mask mask;
66 		u8 flags;
67 	} event;
68 };
69 
state_show(struct device * dev,struct device_attribute * attr,char * buf)70 static ssize_t state_show(struct device *dev, struct device_attribute *attr, char *buf)
71 {
72 	struct ssam_tablet_sw *sw = dev_get_drvdata(dev);
73 	const char *state = sw->ops.state_name(sw, &sw->state);
74 
75 	return sysfs_emit(buf, "%s\n", state);
76 }
77 static DEVICE_ATTR_RO(state);
78 
79 static struct attribute *ssam_tablet_sw_attrs[] = {
80 	&dev_attr_state.attr,
81 	NULL,
82 };
83 
84 static const struct attribute_group ssam_tablet_sw_group = {
85 	.attrs = ssam_tablet_sw_attrs,
86 };
87 
ssam_tablet_sw_update_workfn(struct work_struct * work)88 static void ssam_tablet_sw_update_workfn(struct work_struct *work)
89 {
90 	struct ssam_tablet_sw *sw = container_of(work, struct ssam_tablet_sw, update_work);
91 	struct ssam_tablet_sw_state state;
92 	int tablet, status;
93 
94 	status = sw->ops.get_state(sw, &state);
95 	if (status)
96 		return;
97 
98 	if (sw->state.source == state.source && sw->state.state == state.state)
99 		return;
100 	sw->state = state;
101 
102 	/* Send SW_TABLET_MODE event. */
103 	tablet = sw->ops.state_is_tablet_mode(sw, &state);
104 	input_report_switch(sw->mode_switch, SW_TABLET_MODE, tablet);
105 	input_sync(sw->mode_switch);
106 }
107 
ssam_tablet_sw_resume(struct device * dev)108 static int __maybe_unused ssam_tablet_sw_resume(struct device *dev)
109 {
110 	struct ssam_tablet_sw *sw = dev_get_drvdata(dev);
111 
112 	schedule_work(&sw->update_work);
113 	return 0;
114 }
115 static SIMPLE_DEV_PM_OPS(ssam_tablet_sw_pm_ops, NULL, ssam_tablet_sw_resume);
116 
ssam_tablet_sw_probe(struct ssam_device * sdev)117 static int ssam_tablet_sw_probe(struct ssam_device *sdev)
118 {
119 	const struct ssam_tablet_sw_desc *desc;
120 	struct ssam_tablet_sw *sw;
121 	int tablet, status;
122 
123 	desc = ssam_device_get_match_data(sdev);
124 	if (!desc) {
125 		WARN(1, "no driver match data specified");
126 		return -EINVAL;
127 	}
128 
129 	sw = devm_kzalloc(&sdev->dev, sizeof(*sw), GFP_KERNEL);
130 	if (!sw)
131 		return -ENOMEM;
132 
133 	sw->sdev = sdev;
134 
135 	sw->ops.get_state = desc->ops.get_state;
136 	sw->ops.state_name = desc->ops.state_name;
137 	sw->ops.state_is_tablet_mode = desc->ops.state_is_tablet_mode;
138 
139 	INIT_WORK(&sw->update_work, ssam_tablet_sw_update_workfn);
140 
141 	ssam_device_set_drvdata(sdev, sw);
142 
143 	/* Get initial state. */
144 	status = sw->ops.get_state(sw, &sw->state);
145 	if (status)
146 		return status;
147 
148 	/* Set up tablet mode switch. */
149 	sw->mode_switch = devm_input_allocate_device(&sdev->dev);
150 	if (!sw->mode_switch)
151 		return -ENOMEM;
152 
153 	sw->mode_switch->name = desc->dev.name;
154 	sw->mode_switch->phys = desc->dev.phys;
155 	sw->mode_switch->id.bustype = BUS_HOST;
156 	sw->mode_switch->dev.parent = &sdev->dev;
157 
158 	tablet = sw->ops.state_is_tablet_mode(sw, &sw->state);
159 	input_set_capability(sw->mode_switch, EV_SW, SW_TABLET_MODE);
160 	input_report_switch(sw->mode_switch, SW_TABLET_MODE, tablet);
161 
162 	status = input_register_device(sw->mode_switch);
163 	if (status)
164 		return status;
165 
166 	/* Set up notifier. */
167 	sw->notif.base.priority = 0;
168 	sw->notif.base.fn = desc->ops.notify;
169 	sw->notif.event.reg = desc->event.reg;
170 	sw->notif.event.id = desc->event.id;
171 	sw->notif.event.mask = desc->event.mask;
172 	sw->notif.event.flags = SSAM_EVENT_SEQUENCED;
173 
174 	status = ssam_device_notifier_register(sdev, &sw->notif);
175 	if (status)
176 		return status;
177 
178 	status = sysfs_create_group(&sdev->dev.kobj, &ssam_tablet_sw_group);
179 	if (status)
180 		goto err;
181 
182 	/* We might have missed events during setup, so check again. */
183 	schedule_work(&sw->update_work);
184 	return 0;
185 
186 err:
187 	ssam_device_notifier_unregister(sdev, &sw->notif);
188 	cancel_work_sync(&sw->update_work);
189 	return status;
190 }
191 
ssam_tablet_sw_remove(struct ssam_device * sdev)192 static void ssam_tablet_sw_remove(struct ssam_device *sdev)
193 {
194 	struct ssam_tablet_sw *sw = ssam_device_get_drvdata(sdev);
195 
196 	sysfs_remove_group(&sdev->dev.kobj, &ssam_tablet_sw_group);
197 
198 	ssam_device_notifier_unregister(sdev, &sw->notif);
199 	cancel_work_sync(&sw->update_work);
200 }
201 
202 
203 /* -- SSAM KIP tablet switch implementation. -------------------------------- */
204 
205 #define SSAM_EVENT_KIP_CID_COVER_STATE_CHANGED	0x1d
206 
207 enum ssam_kip_cover_state {
208 	SSAM_KIP_COVER_STATE_DISCONNECTED  = 0x01,
209 	SSAM_KIP_COVER_STATE_CLOSED        = 0x02,
210 	SSAM_KIP_COVER_STATE_LAPTOP        = 0x03,
211 	SSAM_KIP_COVER_STATE_FOLDED_CANVAS = 0x04,
212 	SSAM_KIP_COVER_STATE_FOLDED_BACK   = 0x05,
213 	SSAM_KIP_COVER_STATE_BOOK          = 0x06,
214 };
215 
ssam_kip_cover_state_name(struct ssam_tablet_sw * sw,const struct ssam_tablet_sw_state * state)216 static const char *ssam_kip_cover_state_name(struct ssam_tablet_sw *sw,
217 					     const struct ssam_tablet_sw_state *state)
218 {
219 	switch (state->state) {
220 	case SSAM_KIP_COVER_STATE_DISCONNECTED:
221 		return "disconnected";
222 
223 	case SSAM_KIP_COVER_STATE_CLOSED:
224 		return "closed";
225 
226 	case SSAM_KIP_COVER_STATE_LAPTOP:
227 		return "laptop";
228 
229 	case SSAM_KIP_COVER_STATE_FOLDED_CANVAS:
230 		return "folded-canvas";
231 
232 	case SSAM_KIP_COVER_STATE_FOLDED_BACK:
233 		return "folded-back";
234 
235 	case SSAM_KIP_COVER_STATE_BOOK:
236 		return "book";
237 
238 	default:
239 		dev_warn(&sw->sdev->dev, "unknown KIP cover state: %u\n", state->state);
240 		return "<unknown>";
241 	}
242 }
243 
ssam_kip_cover_state_is_tablet_mode(struct ssam_tablet_sw * sw,const struct ssam_tablet_sw_state * state)244 static bool ssam_kip_cover_state_is_tablet_mode(struct ssam_tablet_sw *sw,
245 						const struct ssam_tablet_sw_state *state)
246 {
247 	switch (state->state) {
248 	case SSAM_KIP_COVER_STATE_DISCONNECTED:
249 	case SSAM_KIP_COVER_STATE_FOLDED_CANVAS:
250 	case SSAM_KIP_COVER_STATE_FOLDED_BACK:
251 	case SSAM_KIP_COVER_STATE_BOOK:
252 		return true;
253 
254 	case SSAM_KIP_COVER_STATE_CLOSED:
255 	case SSAM_KIP_COVER_STATE_LAPTOP:
256 		return false;
257 
258 	default:
259 		dev_warn(&sw->sdev->dev, "unknown KIP cover state: %d\n", state->state);
260 		return true;
261 	}
262 }
263 
264 SSAM_DEFINE_SYNC_REQUEST_R(__ssam_kip_get_cover_state, u8, {
265 	.target_category = SSAM_SSH_TC_KIP,
266 	.target_id       = SSAM_SSH_TID_SAM,
267 	.command_id      = 0x1d,
268 	.instance_id     = 0x00,
269 });
270 
ssam_kip_get_cover_state(struct ssam_tablet_sw * sw,struct ssam_tablet_sw_state * state)271 static int ssam_kip_get_cover_state(struct ssam_tablet_sw *sw, struct ssam_tablet_sw_state *state)
272 {
273 	int status;
274 	u8 raw;
275 
276 	status = ssam_retry(__ssam_kip_get_cover_state, sw->sdev->ctrl, &raw);
277 	if (status < 0) {
278 		dev_err(&sw->sdev->dev, "failed to query KIP lid state: %d\n", status);
279 		return status;
280 	}
281 
282 	state->source = 0;	/* Unused for KIP switch. */
283 	state->state = raw;
284 	return 0;
285 }
286 
ssam_kip_sw_notif(struct ssam_event_notifier * nf,const struct ssam_event * event)287 static u32 ssam_kip_sw_notif(struct ssam_event_notifier *nf, const struct ssam_event *event)
288 {
289 	struct ssam_tablet_sw *sw = container_of(nf, struct ssam_tablet_sw, notif);
290 
291 	if (event->command_id != SSAM_EVENT_KIP_CID_COVER_STATE_CHANGED)
292 		return 0;	/* Return "unhandled". */
293 
294 	if (event->length < 1)
295 		dev_warn(&sw->sdev->dev, "unexpected payload size: %u\n", event->length);
296 
297 	schedule_work(&sw->update_work);
298 	return SSAM_NOTIF_HANDLED;
299 }
300 
301 static const struct ssam_tablet_sw_desc ssam_kip_sw_desc = {
302 	.dev = {
303 		.name = "Microsoft Surface KIP Tablet Mode Switch",
304 		.phys = "ssam/01:0e:01:00:01/input0",
305 	},
306 	.ops = {
307 		.notify = ssam_kip_sw_notif,
308 		.get_state = ssam_kip_get_cover_state,
309 		.state_name = ssam_kip_cover_state_name,
310 		.state_is_tablet_mode = ssam_kip_cover_state_is_tablet_mode,
311 	},
312 	.event = {
313 		.reg = SSAM_EVENT_REGISTRY_SAM,
314 		.id = {
315 			.target_category = SSAM_SSH_TC_KIP,
316 			.instance = 0,
317 		},
318 		.mask = SSAM_EVENT_MASK_TARGET,
319 	},
320 };
321 
322 
323 /* -- SSAM POS tablet switch implementation. -------------------------------- */
324 
325 static bool tablet_mode_in_slate_state = true;
326 module_param(tablet_mode_in_slate_state, bool, 0644);
327 MODULE_PARM_DESC(tablet_mode_in_slate_state, "Enable tablet mode in slate device posture, default is 'true'");
328 
329 #define SSAM_EVENT_POS_CID_POSTURE_CHANGED	0x03
330 #define SSAM_POS_MAX_SOURCES			4
331 
332 enum ssam_pos_source_id {
333 	SSAM_POS_SOURCE_COVER = 0x00,
334 	SSAM_POS_SOURCE_SLS   = 0x03,
335 };
336 
337 enum ssam_pos_state_cover {
338 	SSAM_POS_COVER_DISCONNECTED  = 0x01,
339 	SSAM_POS_COVER_CLOSED        = 0x02,
340 	SSAM_POS_COVER_LAPTOP        = 0x03,
341 	SSAM_POS_COVER_FOLDED_CANVAS = 0x04,
342 	SSAM_POS_COVER_FOLDED_BACK   = 0x05,
343 	SSAM_POS_COVER_BOOK          = 0x06,
344 };
345 
346 enum ssam_pos_state_sls {
347 	SSAM_POS_SLS_LID_CLOSED = 0x00,
348 	SSAM_POS_SLS_LAPTOP     = 0x01,
349 	SSAM_POS_SLS_SLATE      = 0x02,
350 	SSAM_POS_SLS_TABLET     = 0x03,
351 };
352 
353 struct ssam_sources_list {
354 	__le32 count;
355 	__le32 id[SSAM_POS_MAX_SOURCES];
356 } __packed;
357 
ssam_pos_state_name_cover(struct ssam_tablet_sw * sw,u32 state)358 static const char *ssam_pos_state_name_cover(struct ssam_tablet_sw *sw, u32 state)
359 {
360 	switch (state) {
361 	case SSAM_POS_COVER_DISCONNECTED:
362 		return "disconnected";
363 
364 	case SSAM_POS_COVER_CLOSED:
365 		return "closed";
366 
367 	case SSAM_POS_COVER_LAPTOP:
368 		return "laptop";
369 
370 	case SSAM_POS_COVER_FOLDED_CANVAS:
371 		return "folded-canvas";
372 
373 	case SSAM_POS_COVER_FOLDED_BACK:
374 		return "folded-back";
375 
376 	case SSAM_POS_COVER_BOOK:
377 		return "book";
378 
379 	default:
380 		dev_warn(&sw->sdev->dev, "unknown device posture for type-cover: %u\n", state);
381 		return "<unknown>";
382 	}
383 }
384 
ssam_pos_state_name_sls(struct ssam_tablet_sw * sw,u32 state)385 static const char *ssam_pos_state_name_sls(struct ssam_tablet_sw *sw, u32 state)
386 {
387 	switch (state) {
388 	case SSAM_POS_SLS_LID_CLOSED:
389 		return "closed";
390 
391 	case SSAM_POS_SLS_LAPTOP:
392 		return "laptop";
393 
394 	case SSAM_POS_SLS_SLATE:
395 		return "slate";
396 
397 	case SSAM_POS_SLS_TABLET:
398 		return "tablet";
399 
400 	default:
401 		dev_warn(&sw->sdev->dev, "unknown device posture for SLS: %u\n", state);
402 		return "<unknown>";
403 	}
404 }
405 
ssam_pos_state_name(struct ssam_tablet_sw * sw,const struct ssam_tablet_sw_state * state)406 static const char *ssam_pos_state_name(struct ssam_tablet_sw *sw,
407 				       const struct ssam_tablet_sw_state *state)
408 {
409 	switch (state->source) {
410 	case SSAM_POS_SOURCE_COVER:
411 		return ssam_pos_state_name_cover(sw, state->state);
412 
413 	case SSAM_POS_SOURCE_SLS:
414 		return ssam_pos_state_name_sls(sw, state->state);
415 
416 	default:
417 		dev_warn(&sw->sdev->dev, "unknown device posture source: %u\n", state->source);
418 		return "<unknown>";
419 	}
420 }
421 
ssam_pos_state_is_tablet_mode_cover(struct ssam_tablet_sw * sw,u32 state)422 static bool ssam_pos_state_is_tablet_mode_cover(struct ssam_tablet_sw *sw, u32 state)
423 {
424 	switch (state) {
425 	case SSAM_POS_COVER_DISCONNECTED:
426 	case SSAM_POS_COVER_FOLDED_CANVAS:
427 	case SSAM_POS_COVER_FOLDED_BACK:
428 	case SSAM_POS_COVER_BOOK:
429 		return true;
430 
431 	case SSAM_POS_COVER_CLOSED:
432 	case SSAM_POS_COVER_LAPTOP:
433 		return false;
434 
435 	default:
436 		dev_warn(&sw->sdev->dev, "unknown device posture for type-cover: %u\n", state);
437 		return true;
438 	}
439 }
440 
ssam_pos_state_is_tablet_mode_sls(struct ssam_tablet_sw * sw,u32 state)441 static bool ssam_pos_state_is_tablet_mode_sls(struct ssam_tablet_sw *sw, u32 state)
442 {
443 	switch (state) {
444 	case SSAM_POS_SLS_LAPTOP:
445 	case SSAM_POS_SLS_LID_CLOSED:
446 		return false;
447 
448 	case SSAM_POS_SLS_SLATE:
449 		return tablet_mode_in_slate_state;
450 
451 	case SSAM_POS_SLS_TABLET:
452 		return true;
453 
454 	default:
455 		dev_warn(&sw->sdev->dev, "unknown device posture for SLS: %u\n", state);
456 		return true;
457 	}
458 }
459 
ssam_pos_state_is_tablet_mode(struct ssam_tablet_sw * sw,const struct ssam_tablet_sw_state * state)460 static bool ssam_pos_state_is_tablet_mode(struct ssam_tablet_sw *sw,
461 					  const struct ssam_tablet_sw_state *state)
462 {
463 	switch (state->source) {
464 	case SSAM_POS_SOURCE_COVER:
465 		return ssam_pos_state_is_tablet_mode_cover(sw, state->state);
466 
467 	case SSAM_POS_SOURCE_SLS:
468 		return ssam_pos_state_is_tablet_mode_sls(sw, state->state);
469 
470 	default:
471 		dev_warn(&sw->sdev->dev, "unknown device posture source: %u\n", state->source);
472 		return true;
473 	}
474 }
475 
ssam_pos_get_sources_list(struct ssam_tablet_sw * sw,struct ssam_sources_list * sources)476 static int ssam_pos_get_sources_list(struct ssam_tablet_sw *sw, struct ssam_sources_list *sources)
477 {
478 	struct ssam_request rqst;
479 	struct ssam_response rsp;
480 	int status;
481 
482 	rqst.target_category = SSAM_SSH_TC_POS;
483 	rqst.target_id = SSAM_SSH_TID_SAM;
484 	rqst.command_id = 0x01;
485 	rqst.instance_id = 0x00;
486 	rqst.flags = SSAM_REQUEST_HAS_RESPONSE;
487 	rqst.length = 0;
488 	rqst.payload = NULL;
489 
490 	rsp.capacity = sizeof(*sources);
491 	rsp.length = 0;
492 	rsp.pointer = (u8 *)sources;
493 
494 	status = ssam_retry(ssam_request_do_sync_onstack, sw->sdev->ctrl, &rqst, &rsp, 0);
495 	if (status)
496 		return status;
497 
498 	/* We need at least the 'sources->count' field. */
499 	if (rsp.length < sizeof(__le32)) {
500 		dev_err(&sw->sdev->dev, "received source list response is too small\n");
501 		return -EPROTO;
502 	}
503 
504 	/* Make sure 'sources->count' matches with the response length. */
505 	if (get_unaligned_le32(&sources->count) * sizeof(__le32) + sizeof(__le32) != rsp.length) {
506 		dev_err(&sw->sdev->dev, "mismatch between number of sources and response size\n");
507 		return -EPROTO;
508 	}
509 
510 	return 0;
511 }
512 
ssam_pos_get_source(struct ssam_tablet_sw * sw,u32 * source_id)513 static int ssam_pos_get_source(struct ssam_tablet_sw *sw, u32 *source_id)
514 {
515 	struct ssam_sources_list sources = {};
516 	int status;
517 
518 	status = ssam_pos_get_sources_list(sw, &sources);
519 	if (status)
520 		return status;
521 
522 	if (get_unaligned_le32(&sources.count) == 0) {
523 		dev_err(&sw->sdev->dev, "no posture sources found\n");
524 		return -ENODEV;
525 	}
526 
527 	/*
528 	 * We currently don't know what to do with more than one posture
529 	 * source. At the moment, only one source seems to be used/provided.
530 	 * The WARN_ON() here should hopefully let us know quickly once there
531 	 * is a device that provides multiple sources, at which point we can
532 	 * then try to figure out how to handle them.
533 	 */
534 	WARN_ON(get_unaligned_le32(&sources.count) > 1);
535 
536 	*source_id = get_unaligned_le32(&sources.id[0]);
537 	return 0;
538 }
539 
540 SSAM_DEFINE_SYNC_REQUEST_WR(__ssam_pos_get_posture_for_source, __le32, __le32, {
541 	.target_category = SSAM_SSH_TC_POS,
542 	.target_id       = SSAM_SSH_TID_SAM,
543 	.command_id      = 0x02,
544 	.instance_id     = 0x00,
545 });
546 
ssam_pos_get_posture_for_source(struct ssam_tablet_sw * sw,u32 source_id,u32 * posture)547 static int ssam_pos_get_posture_for_source(struct ssam_tablet_sw *sw, u32 source_id, u32 *posture)
548 {
549 	__le32 source_le = cpu_to_le32(source_id);
550 	__le32 rspval_le = 0;
551 	int status;
552 
553 	status = ssam_retry(__ssam_pos_get_posture_for_source, sw->sdev->ctrl,
554 			    &source_le, &rspval_le);
555 	if (status)
556 		return status;
557 
558 	*posture = le32_to_cpu(rspval_le);
559 	return 0;
560 }
561 
ssam_pos_get_posture(struct ssam_tablet_sw * sw,struct ssam_tablet_sw_state * state)562 static int ssam_pos_get_posture(struct ssam_tablet_sw *sw, struct ssam_tablet_sw_state *state)
563 {
564 	u32 source_id;
565 	u32 source_state;
566 	int status;
567 
568 	status = ssam_pos_get_source(sw, &source_id);
569 	if (status) {
570 		dev_err(&sw->sdev->dev, "failed to get posture source ID: %d\n", status);
571 		return status;
572 	}
573 
574 	status = ssam_pos_get_posture_for_source(sw, source_id, &source_state);
575 	if (status) {
576 		dev_err(&sw->sdev->dev, "failed to get posture value for source %u: %d\n",
577 			source_id, status);
578 		return status;
579 	}
580 
581 	state->source = source_id;
582 	state->state = source_state;
583 	return 0;
584 }
585 
ssam_pos_sw_notif(struct ssam_event_notifier * nf,const struct ssam_event * event)586 static u32 ssam_pos_sw_notif(struct ssam_event_notifier *nf, const struct ssam_event *event)
587 {
588 	struct ssam_tablet_sw *sw = container_of(nf, struct ssam_tablet_sw, notif);
589 
590 	if (event->command_id != SSAM_EVENT_POS_CID_POSTURE_CHANGED)
591 		return 0;	/* Return "unhandled". */
592 
593 	if (event->length != sizeof(__le32) * 3)
594 		dev_warn(&sw->sdev->dev, "unexpected payload size: %u\n", event->length);
595 
596 	schedule_work(&sw->update_work);
597 	return SSAM_NOTIF_HANDLED;
598 }
599 
600 static const struct ssam_tablet_sw_desc ssam_pos_sw_desc = {
601 	.dev = {
602 		.name = "Microsoft Surface POS Tablet Mode Switch",
603 		.phys = "ssam/01:26:01:00:01/input0",
604 	},
605 	.ops = {
606 		.notify = ssam_pos_sw_notif,
607 		.get_state = ssam_pos_get_posture,
608 		.state_name = ssam_pos_state_name,
609 		.state_is_tablet_mode = ssam_pos_state_is_tablet_mode,
610 	},
611 	.event = {
612 		.reg = SSAM_EVENT_REGISTRY_SAM,
613 		.id = {
614 			.target_category = SSAM_SSH_TC_POS,
615 			.instance = 0,
616 		},
617 		.mask = SSAM_EVENT_MASK_TARGET,
618 	},
619 };
620 
621 
622 /* -- Driver registration. -------------------------------------------------- */
623 
624 static const struct ssam_device_id ssam_tablet_sw_match[] = {
625 	{ SSAM_SDEV(KIP, SAM, 0x00, 0x01), (unsigned long)&ssam_kip_sw_desc },
626 	{ SSAM_SDEV(POS, SAM, 0x00, 0x01), (unsigned long)&ssam_pos_sw_desc },
627 	{ },
628 };
629 MODULE_DEVICE_TABLE(ssam, ssam_tablet_sw_match);
630 
631 static struct ssam_device_driver ssam_tablet_sw_driver = {
632 	.probe = ssam_tablet_sw_probe,
633 	.remove = ssam_tablet_sw_remove,
634 	.match_table = ssam_tablet_sw_match,
635 	.driver = {
636 		.name = "surface_aggregator_tablet_mode_switch",
637 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
638 		.pm = &ssam_tablet_sw_pm_ops,
639 	},
640 };
641 module_ssam_device_driver(ssam_tablet_sw_driver);
642 
643 MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
644 MODULE_DESCRIPTION("Tablet mode switch driver for Surface devices using the Surface Aggregator Module");
645 MODULE_LICENSE("GPL");
646