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