1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3    Dell Airplane Mode Switch driver
4    Copyright (C) 2014-2015  Pali Rohár <pali@kernel.org>
5
6*/
7
8#include <linux/module.h>
9#include <linux/acpi.h>
10#include <linux/rfkill.h>
11#include <linux/input.h>
12
13#include "dell-rbtn.h"
14
15enum rbtn_type {
16	RBTN_UNKNOWN,
17	RBTN_TOGGLE,
18	RBTN_SLIDER,
19};
20
21struct rbtn_data {
22	enum rbtn_type type;
23	struct rfkill *rfkill;
24	struct input_dev *input_dev;
25	bool suspended;
26};
27
28
29/*
30 * acpi functions
31 */
32
33static enum rbtn_type rbtn_check(struct acpi_device *device)
34{
35	unsigned long long output;
36	acpi_status status;
37
38	status = acpi_evaluate_integer(device->handle, "CRBT", NULL, &output);
39	if (ACPI_FAILURE(status))
40		return RBTN_UNKNOWN;
41
42	switch (output) {
43	case 0:
44	case 1:
45		return RBTN_TOGGLE;
46	case 2:
47	case 3:
48		return RBTN_SLIDER;
49	default:
50		return RBTN_UNKNOWN;
51	}
52}
53
54static int rbtn_get(struct acpi_device *device)
55{
56	unsigned long long output;
57	acpi_status status;
58
59	status = acpi_evaluate_integer(device->handle, "GRBT", NULL, &output);
60	if (ACPI_FAILURE(status))
61		return -EINVAL;
62
63	return !output;
64}
65
66static int rbtn_acquire(struct acpi_device *device, bool enable)
67{
68	struct acpi_object_list input;
69	union acpi_object param;
70	acpi_status status;
71
72	param.type = ACPI_TYPE_INTEGER;
73	param.integer.value = enable;
74	input.count = 1;
75	input.pointer = &param;
76
77	status = acpi_evaluate_object(device->handle, "ARBT", &input, NULL);
78	if (ACPI_FAILURE(status))
79		return -EINVAL;
80
81	return 0;
82}
83
84
85/*
86 * rfkill device
87 */
88
89static void rbtn_rfkill_query(struct rfkill *rfkill, void *data)
90{
91	struct acpi_device *device = data;
92	int state;
93
94	state = rbtn_get(device);
95	if (state < 0)
96		return;
97
98	rfkill_set_states(rfkill, state, state);
99}
100
101static int rbtn_rfkill_set_block(void *data, bool blocked)
102{
103	/* NOTE: setting soft rfkill state is not supported */
104	return -EINVAL;
105}
106
107static const struct rfkill_ops rbtn_ops = {
108	.query = rbtn_rfkill_query,
109	.set_block = rbtn_rfkill_set_block,
110};
111
112static int rbtn_rfkill_init(struct acpi_device *device)
113{
114	struct rbtn_data *rbtn_data = device->driver_data;
115	int ret;
116
117	if (rbtn_data->rfkill)
118		return 0;
119
120	/*
121	 * NOTE: rbtn controls all radio devices, not only WLAN
122	 *       but rfkill interface does not support "ANY" type
123	 *       so "WLAN" type is used
124	 */
125	rbtn_data->rfkill = rfkill_alloc("dell-rbtn", &device->dev,
126					 RFKILL_TYPE_WLAN, &rbtn_ops, device);
127	if (!rbtn_data->rfkill)
128		return -ENOMEM;
129
130	ret = rfkill_register(rbtn_data->rfkill);
131	if (ret) {
132		rfkill_destroy(rbtn_data->rfkill);
133		rbtn_data->rfkill = NULL;
134		return ret;
135	}
136
137	return 0;
138}
139
140static void rbtn_rfkill_exit(struct acpi_device *device)
141{
142	struct rbtn_data *rbtn_data = device->driver_data;
143
144	if (!rbtn_data->rfkill)
145		return;
146
147	rfkill_unregister(rbtn_data->rfkill);
148	rfkill_destroy(rbtn_data->rfkill);
149	rbtn_data->rfkill = NULL;
150}
151
152static void rbtn_rfkill_event(struct acpi_device *device)
153{
154	struct rbtn_data *rbtn_data = device->driver_data;
155
156	if (rbtn_data->rfkill)
157		rbtn_rfkill_query(rbtn_data->rfkill, device);
158}
159
160
161/*
162 * input device
163 */
164
165static int rbtn_input_init(struct rbtn_data *rbtn_data)
166{
167	int ret;
168
169	rbtn_data->input_dev = input_allocate_device();
170	if (!rbtn_data->input_dev)
171		return -ENOMEM;
172
173	rbtn_data->input_dev->name = "DELL Wireless hotkeys";
174	rbtn_data->input_dev->phys = "dellabce/input0";
175	rbtn_data->input_dev->id.bustype = BUS_HOST;
176	rbtn_data->input_dev->evbit[0] = BIT(EV_KEY);
177	set_bit(KEY_RFKILL, rbtn_data->input_dev->keybit);
178
179	ret = input_register_device(rbtn_data->input_dev);
180	if (ret) {
181		input_free_device(rbtn_data->input_dev);
182		rbtn_data->input_dev = NULL;
183		return ret;
184	}
185
186	return 0;
187}
188
189static void rbtn_input_exit(struct rbtn_data *rbtn_data)
190{
191	input_unregister_device(rbtn_data->input_dev);
192	rbtn_data->input_dev = NULL;
193}
194
195static void rbtn_input_event(struct rbtn_data *rbtn_data)
196{
197	input_report_key(rbtn_data->input_dev, KEY_RFKILL, 1);
198	input_sync(rbtn_data->input_dev);
199	input_report_key(rbtn_data->input_dev, KEY_RFKILL, 0);
200	input_sync(rbtn_data->input_dev);
201}
202
203
204/*
205 * acpi driver
206 */
207
208static int rbtn_add(struct acpi_device *device);
209static void rbtn_remove(struct acpi_device *device);
210static void rbtn_notify(struct acpi_device *device, u32 event);
211
212static const struct acpi_device_id rbtn_ids[] = {
213	{ "DELRBTN", 0 },
214	{ "DELLABCE", 0 },
215
216	/*
217	 * This driver can also handle the "DELLABC6" device that
218	 * appears on the XPS 13 9350, but that device is disabled by
219	 * the DSDT unless booted with acpi_osi="!Windows 2012"
220	 * acpi_osi="!Windows 2013".
221	 *
222	 * According to Mario at Dell:
223	 *
224	 *  DELLABC6 is a custom interface that was created solely to
225	 *  have airplane mode support for Windows 7.  For Windows 10
226	 *  the proper interface is to use that which is handled by
227	 *  intel-hid. A OEM airplane mode driver is not used.
228	 *
229	 *  Since the kernel doesn't identify as Windows 7 it would be
230	 *  incorrect to do attempt to use that interface.
231	 *
232	 * Even if we override _OSI and bind to DELLABC6, we end up with
233	 * inconsistent behavior in which userspace can get out of sync
234	 * with the rfkill state as it conflicts with events from
235	 * intel-hid.
236	 *
237	 * The upshot is that it is better to just ignore DELLABC6
238	 * devices.
239	 */
240
241	{ "", 0 },
242};
243
244#ifdef CONFIG_PM_SLEEP
245static void ACPI_SYSTEM_XFACE rbtn_clear_suspended_flag(void *context)
246{
247	struct rbtn_data *rbtn_data = context;
248
249	rbtn_data->suspended = false;
250}
251
252static int rbtn_suspend(struct device *dev)
253{
254	struct acpi_device *device = to_acpi_device(dev);
255	struct rbtn_data *rbtn_data = acpi_driver_data(device);
256
257	rbtn_data->suspended = true;
258
259	return 0;
260}
261
262static int rbtn_resume(struct device *dev)
263{
264	struct acpi_device *device = to_acpi_device(dev);
265	struct rbtn_data *rbtn_data = acpi_driver_data(device);
266	acpi_status status;
267
268	/*
269	 * Upon resume, some BIOSes send an ACPI notification thet triggers
270	 * an unwanted input event. In order to ignore it, we use a flag
271	 * that we set at suspend and clear once we have received the extra
272	 * ACPI notification. Since ACPI notifications are delivered
273	 * asynchronously to drivers, we clear the flag from the workqueue
274	 * used to deliver the notifications. This should be enough
275	 * to have the flag cleared only after we received the extra
276	 * notification, if any.
277	 */
278	status = acpi_os_execute(OSL_NOTIFY_HANDLER,
279			 rbtn_clear_suspended_flag, rbtn_data);
280	if (ACPI_FAILURE(status))
281		rbtn_clear_suspended_flag(rbtn_data);
282
283	return 0;
284}
285#endif
286
287static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume);
288
289static struct acpi_driver rbtn_driver = {
290	.name = "dell-rbtn",
291	.ids = rbtn_ids,
292	.drv.pm = &rbtn_pm_ops,
293	.ops = {
294		.add = rbtn_add,
295		.remove = rbtn_remove,
296		.notify = rbtn_notify,
297	},
298	.owner = THIS_MODULE,
299};
300
301
302/*
303 * notifier export functions
304 */
305
306static bool auto_remove_rfkill = true;
307
308static ATOMIC_NOTIFIER_HEAD(rbtn_chain_head);
309
310static int rbtn_inc_count(struct device *dev, void *data)
311{
312	struct acpi_device *device = to_acpi_device(dev);
313	struct rbtn_data *rbtn_data = device->driver_data;
314	int *count = data;
315
316	if (rbtn_data->type == RBTN_SLIDER)
317		(*count)++;
318
319	return 0;
320}
321
322static int rbtn_switch_dev(struct device *dev, void *data)
323{
324	struct acpi_device *device = to_acpi_device(dev);
325	struct rbtn_data *rbtn_data = device->driver_data;
326	bool enable = data;
327
328	if (rbtn_data->type != RBTN_SLIDER)
329		return 0;
330
331	if (enable)
332		rbtn_rfkill_init(device);
333	else
334		rbtn_rfkill_exit(device);
335
336	return 0;
337}
338
339int dell_rbtn_notifier_register(struct notifier_block *nb)
340{
341	bool first;
342	int count;
343	int ret;
344
345	count = 0;
346	ret = driver_for_each_device(&rbtn_driver.drv, NULL, &count,
347				     rbtn_inc_count);
348	if (ret || count == 0)
349		return -ENODEV;
350
351	first = !rbtn_chain_head.head;
352
353	ret = atomic_notifier_chain_register(&rbtn_chain_head, nb);
354	if (ret != 0)
355		return ret;
356
357	if (auto_remove_rfkill && first)
358		ret = driver_for_each_device(&rbtn_driver.drv, NULL,
359					     (void *)false, rbtn_switch_dev);
360
361	return ret;
362}
363EXPORT_SYMBOL_GPL(dell_rbtn_notifier_register);
364
365int dell_rbtn_notifier_unregister(struct notifier_block *nb)
366{
367	int ret;
368
369	ret = atomic_notifier_chain_unregister(&rbtn_chain_head, nb);
370	if (ret != 0)
371		return ret;
372
373	if (auto_remove_rfkill && !rbtn_chain_head.head)
374		ret = driver_for_each_device(&rbtn_driver.drv, NULL,
375					     (void *)true, rbtn_switch_dev);
376
377	return ret;
378}
379EXPORT_SYMBOL_GPL(dell_rbtn_notifier_unregister);
380
381
382/*
383 * acpi driver functions
384 */
385
386static int rbtn_add(struct acpi_device *device)
387{
388	struct rbtn_data *rbtn_data;
389	enum rbtn_type type;
390	int ret = 0;
391
392	type = rbtn_check(device);
393	if (type == RBTN_UNKNOWN) {
394		dev_info(&device->dev, "Unknown device type\n");
395		return -EINVAL;
396	}
397
398	rbtn_data = devm_kzalloc(&device->dev, sizeof(*rbtn_data), GFP_KERNEL);
399	if (!rbtn_data)
400		return -ENOMEM;
401
402	ret = rbtn_acquire(device, true);
403	if (ret < 0) {
404		dev_err(&device->dev, "Cannot enable device\n");
405		return ret;
406	}
407
408	rbtn_data->type = type;
409	device->driver_data = rbtn_data;
410
411	switch (rbtn_data->type) {
412	case RBTN_TOGGLE:
413		ret = rbtn_input_init(rbtn_data);
414		break;
415	case RBTN_SLIDER:
416		if (auto_remove_rfkill && rbtn_chain_head.head)
417			ret = 0;
418		else
419			ret = rbtn_rfkill_init(device);
420		break;
421	default:
422		ret = -EINVAL;
423		break;
424	}
425	if (ret)
426		rbtn_acquire(device, false);
427
428	return ret;
429}
430
431static void rbtn_remove(struct acpi_device *device)
432{
433	struct rbtn_data *rbtn_data = device->driver_data;
434
435	switch (rbtn_data->type) {
436	case RBTN_TOGGLE:
437		rbtn_input_exit(rbtn_data);
438		break;
439	case RBTN_SLIDER:
440		rbtn_rfkill_exit(device);
441		break;
442	default:
443		break;
444	}
445
446	rbtn_acquire(device, false);
447}
448
449static void rbtn_notify(struct acpi_device *device, u32 event)
450{
451	struct rbtn_data *rbtn_data = device->driver_data;
452
453	/*
454	 * Some BIOSes send a notification at resume.
455	 * Ignore it to prevent unwanted input events.
456	 */
457	if (rbtn_data->suspended) {
458		dev_dbg(&device->dev, "ACPI notification ignored\n");
459		return;
460	}
461
462	if (event != 0x80) {
463		dev_info(&device->dev, "Received unknown event (0x%x)\n",
464			 event);
465		return;
466	}
467
468	switch (rbtn_data->type) {
469	case RBTN_TOGGLE:
470		rbtn_input_event(rbtn_data);
471		break;
472	case RBTN_SLIDER:
473		rbtn_rfkill_event(device);
474		atomic_notifier_call_chain(&rbtn_chain_head, event, device);
475		break;
476	default:
477		break;
478	}
479}
480
481
482/*
483 * module functions
484 */
485
486module_acpi_driver(rbtn_driver);
487
488module_param(auto_remove_rfkill, bool, 0444);
489
490MODULE_PARM_DESC(auto_remove_rfkill, "Automatically remove rfkill devices when "
491				     "other modules start receiving events "
492				     "from this module and re-add them when "
493				     "the last module stops receiving events "
494				     "(default true)");
495MODULE_DEVICE_TABLE(acpi, rbtn_ids);
496MODULE_DESCRIPTION("Dell Airplane Mode Switch driver");
497MODULE_AUTHOR("Pali Rohár <pali@kernel.org>");
498MODULE_LICENSE("GPL");
499