summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/mei_wdt.c
blob: ea60b29494fb693bf7898e3f456b6ff8e9dfdb6f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
/*
 * Intel Management Engine Interface (Intel MEI) Linux driver
 * Copyright (c) 2015, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/debugfs.h>
#include <linux/completion.h>
#include <linux/watchdog.h>

#include <linux/uuid.h>
#include <linux/mei_cl_bus.h>

/*
 * iAMT Watchdog Device
 */
#define INTEL_AMT_WATCHDOG_ID "iamt_wdt"

#define MEI_WDT_DEFAULT_TIMEOUT   120  /* seconds */
#define MEI_WDT_MIN_TIMEOUT       120  /* seconds */
#define MEI_WDT_MAX_TIMEOUT     65535  /* seconds */

/* Commands */
#define MEI_MANAGEMENT_CONTROL 0x02

/* MEI Management Control version number */
#define MEI_MC_VERSION_NUMBER  0x10

/* Sub Commands */
#define MEI_MC_START_WD_TIMER_REQ  0x13
#define MEI_MC_START_WD_TIMER_RES  0x83
#define   MEI_WDT_STATUS_SUCCESS 0
#define   MEI_WDT_WDSTATE_NOT_REQUIRED 0x1
#define MEI_MC_STOP_WD_TIMER_REQ   0x14

/**
 * enum mei_wdt_state - internal watchdog state
 *
 * @MEI_WDT_PROBE: wd in probing stage
 * @MEI_WDT_IDLE: wd is idle and not opened
 * @MEI_WDT_START: wd was opened, start was called
 * @MEI_WDT_RUNNING: wd is expecting keep alive pings
 * @MEI_WDT_STOPPING: wd is stopping and will move to IDLE
 * @MEI_WDT_NOT_REQUIRED: wd device is not required
 */
enum mei_wdt_state {
	MEI_WDT_PROBE,
	MEI_WDT_IDLE,
	MEI_WDT_START,
	MEI_WDT_RUNNING,
	MEI_WDT_STOPPING,
	MEI_WDT_NOT_REQUIRED,
};

static const char *mei_wdt_state_str(enum mei_wdt_state state)
{
	switch (state) {
	case MEI_WDT_PROBE:
		return "PROBE";
	case MEI_WDT_IDLE:
		return "IDLE";
	case MEI_WDT_START:
		return "START";
	case MEI_WDT_RUNNING:
		return "RUNNING";
	case MEI_WDT_STOPPING:
		return "STOPPING";
	case MEI_WDT_NOT_REQUIRED:
		return "NOT_REQUIRED";
	default:
		return "unknown";
	}
}

/**
 * struct mei_wdt - mei watchdog driver
 * @wdd: watchdog device
 *
 * @cldev: mei watchdog client device
 * @state: watchdog internal state
 * @resp_required: ping required response
 * @response: ping response completion
 * @unregister: unregister worker
 * @reg_lock: watchdog device registration lock
 * @timeout: watchdog current timeout
 *
 * @dbgfs_dir: debugfs dir entry
 */
struct mei_wdt {
	struct watchdog_device wdd;

	struct mei_cl_device *cldev;
	enum mei_wdt_state state;
	bool resp_required;
	struct completion response;
	struct work_struct unregister;
	struct mutex reg_lock;
	u16 timeout;

#if IS_ENABLED(CONFIG_DEBUG_FS)
	struct dentry *dbgfs_dir;
#endif /* CONFIG_DEBUG_FS */
};

/*
 * struct mei_mc_hdr - Management Control Command Header
 *
 * @command: Management Control (0x2)
 * @bytecount: Number of bytes in the message beyond this byte
 * @subcommand: Management Control Subcommand
 * @versionnumber: Management Control Version (0x10)
 */
struct mei_mc_hdr {
	u8 command;
	u8 bytecount;
	u8 subcommand;
	u8 versionnumber;
};

/**
 * struct mei_wdt_start_request watchdog start/ping
 *
 * @hdr: Management Control Command Header
 * @timeout: timeout value
 * @reserved: reserved (legacy)
 */
struct mei_wdt_start_request {
	struct mei_mc_hdr hdr;
	u16 timeout;
	u8 reserved[17];
} __packed;

/**
 * struct mei_wdt_start_response watchdog start/ping response
 *
 * @hdr: Management Control Command Header
 * @status: operation status
 * @wdstate: watchdog status bit mask
 */
struct mei_wdt_start_response {
	struct mei_mc_hdr hdr;
	u8 status;
	u8 wdstate;
} __packed;

/**
 * struct mei_wdt_stop_request - watchdog stop
 *
 * @hdr: Management Control Command Header
 */
struct mei_wdt_stop_request {
	struct mei_mc_hdr hdr;
} __packed;

/**
 * mei_wdt_ping - send wd start/ping command
 *
 * @wdt: mei watchdog device
 *
 * Return: 0 on success,
 *         negative errno code on failure
 */
static int mei_wdt_ping(struct mei_wdt *wdt)
{
	struct mei_wdt_start_request req;
	const size_t req_len = sizeof(req);
	int ret;

	memset(&req, 0, req_len);
	req.hdr.command = MEI_MANAGEMENT_CONTROL;
	req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
	req.hdr.subcommand = MEI_MC_START_WD_TIMER_REQ;
	req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
	req.timeout = wdt->timeout;

	ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
	if (ret < 0)
		return ret;

	return 0;
}

/**
 * mei_wdt_stop - send wd stop command
 *
 * @wdt: mei watchdog device
 *
 * Return: 0 on success,
 *         negative errno code on failure
 */
static int mei_wdt_stop(struct mei_wdt *wdt)
{
	struct mei_wdt_stop_request req;
	const size_t req_len = sizeof(req);
	int ret;

	memset(&req, 0, req_len);
	req.hdr.command = MEI_MANAGEMENT_CONTROL;
	req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
	req.hdr.subcommand = MEI_MC_STOP_WD_TIMER_REQ;
	req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;

	ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
	if (ret < 0)
		return ret;

	return 0;
}

/**
 * mei_wdt_ops_start - wd start command from the watchdog core.
 *
 * @wdd: watchdog device
 *
 * Return: 0 on success or -ENODEV;
 */
static int mei_wdt_ops_start(struct watchdog_device *wdd)
{
	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);

	wdt->state = MEI_WDT_START;
	wdd->timeout = wdt->timeout;
	return 0;
}

/**
 * mei_wdt_ops_stop - wd stop command from the watchdog core.
 *
 * @wdd: watchdog device
 *
 * Return: 0 if success, negative errno code for failure
 */
static int mei_wdt_ops_stop(struct watchdog_device *wdd)
{
	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
	int ret;

	if (wdt->state != MEI_WDT_RUNNING)
		return 0;

	wdt->state = MEI_WDT_STOPPING;

	ret = mei_wdt_stop(wdt);
	if (ret)
		return ret;

	wdt->state = MEI_WDT_IDLE;

	return 0;
}

/**
 * mei_wdt_ops_ping - wd ping command from the watchdog core.
 *
 * @wdd: watchdog device
 *
 * Return: 0 if success, negative errno code on failure
 */
static int mei_wdt_ops_ping(struct watchdog_device *wdd)
{
	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
	int ret;

	if (wdt->state != MEI_WDT_START && wdt->state != MEI_WDT_RUNNING)
		return 0;

	if (wdt->resp_required)
		init_completion(&wdt->response);

	wdt->state = MEI_WDT_RUNNING;
	ret = mei_wdt_ping(wdt);
	if (ret)
		return ret;

	if (wdt->resp_required)
		ret = wait_for_completion_killable(&wdt->response);

	return ret;
}

/**
 * mei_wdt_ops_set_timeout - wd set timeout command from the watchdog core.
 *
 * @wdd: watchdog device
 * @timeout: timeout value to set
 *
 * Return: 0 if success, negative errno code for failure
 */
static int mei_wdt_ops_set_timeout(struct watchdog_device *wdd,
				   unsigned int timeout)
{

	struct mei_wdt *wdt = watchdog_get_drvdata(wdd);

	/* valid value is already checked by the caller */
	wdt->timeout = timeout;
	wdd->timeout = timeout;

	return 0;
}

static const struct watchdog_ops wd_ops = {
	.owner       = THIS_MODULE,
	.start       = mei_wdt_ops_start,
	.stop        = mei_wdt_ops_stop,
	.ping        = mei_wdt_ops_ping,
	.set_timeout = mei_wdt_ops_set_timeout,
};

/* not const as the firmware_version field need to be retrieved */
static struct watchdog_info wd_info = {
	.identity = INTEL_AMT_WATCHDOG_ID,
	.options  = WDIOF_KEEPALIVEPING |
		    WDIOF_SETTIMEOUT |
		    WDIOF_ALARMONLY,
};

/**
 * __mei_wdt_is_registered - check if wdt is registered
 *
 * @wdt: mei watchdog device
 *
 * Return: true if the wdt is registered with the watchdog subsystem
 * Locking: should be called under wdt->reg_lock
 */
static inline bool __mei_wdt_is_registered(struct mei_wdt *wdt)
{
	return !!watchdog_get_drvdata(&wdt->wdd);
}

/**
 * mei_wdt_unregister - unregister from the watchdog subsystem
 *
 * @wdt: mei watchdog device
 */
static void mei_wdt_unregister(struct mei_wdt *wdt)
{
	mutex_lock(&wdt->reg_lock);

	if (__mei_wdt_is_registered(wdt)) {
		watchdog_unregister_device(&wdt->wdd);
		watchdog_set_drvdata(&wdt->wdd, NULL);
		memset(&wdt->wdd, 0, sizeof(wdt->wdd));
	}

	mutex_unlock(&wdt->reg_lock);
}

/**
 * mei_wdt_register - register with the watchdog subsystem
 *
 * @wdt: mei watchdog device
 *
 * Return: 0 if success, negative errno code for failure
 */
static int mei_wdt_register(struct mei_wdt *wdt)
{
	struct device *dev;
	int ret;

	if (!wdt || !wdt->cldev)
		return -EINVAL;

	dev = &wdt->cldev->dev;

	mutex_lock(&wdt->reg_lock);

	if (__mei_wdt_is_registered(wdt)) {
		ret = 0;
		goto out;
	}

	wdt->wdd.info = &wd_info;
	wdt->wdd.ops = &wd_ops;
	wdt->wdd.parent = dev;
	wdt->wdd.timeout = MEI_WDT_DEFAULT_TIMEOUT;
	wdt->wdd.min_timeout = MEI_WDT_MIN_TIMEOUT;
	wdt->wdd.max_timeout = MEI_WDT_MAX_TIMEOUT;

	watchdog_set_drvdata(&wdt->wdd, wdt);
	watchdog_stop_on_reboot(&wdt->wdd);

	ret = watchdog_register_device(&wdt->wdd);
	if (ret) {
		dev_err(dev, "unable to register watchdog device = %d.\n", ret);
		watchdog_set_drvdata(&wdt->wdd, NULL);
	}

	wdt->state = MEI_WDT_IDLE;

out:
	mutex_unlock(&wdt->reg_lock);
	return ret;
}

static void mei_wdt_unregister_work(struct work_struct *work)
{
	struct mei_wdt *wdt = container_of(work, struct mei_wdt, unregister);

	mei_wdt_unregister(wdt);
}

/**
 * mei_wdt_rx - callback for data receive
 *
 * @cldev: bus device
 */
static void mei_wdt_rx(struct mei_cl_device *cldev)
{
	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
	struct mei_wdt_start_response res;
	const size_t res_len = sizeof(res);
	int ret;

	ret = mei_cldev_recv(wdt->cldev, (u8 *)&res, res_len);
	if (ret < 0) {
		dev_err(&cldev->dev, "failure in recv %d\n", ret);
		return;
	}

	/* Empty response can be sent on stop */
	if (ret == 0)
		return;

	if (ret < sizeof(struct mei_mc_hdr)) {
		dev_err(&cldev->dev, "recv small data %d\n", ret);
		return;
	}

	if (res.hdr.command != MEI_MANAGEMENT_CONTROL ||
	    res.hdr.versionnumber != MEI_MC_VERSION_NUMBER) {
		dev_err(&cldev->dev, "wrong command received\n");
		return;
	}

	if (res.hdr.subcommand != MEI_MC_START_WD_TIMER_RES) {
		dev_warn(&cldev->dev, "unsupported command %d :%s[%d]\n",
			 res.hdr.subcommand,
			 mei_wdt_state_str(wdt->state),
			 wdt->state);
		return;
	}

	/* Run the unregistration in a worker as this can be
	 * run only after ping completion, otherwise the flow will
	 * deadlock on watchdog core mutex.
	 */
	if (wdt->state == MEI_WDT_RUNNING) {
		if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
			wdt->state = MEI_WDT_NOT_REQUIRED;
			schedule_work(&wdt->unregister);
		}
		goto out;
	}

	if (wdt->state == MEI_WDT_PROBE) {
		if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
			wdt->state = MEI_WDT_NOT_REQUIRED;
		} else {
			/* stop the watchdog and register watchdog device */
			mei_wdt_stop(wdt);
			mei_wdt_register(wdt);
		}
		return;
	}

	dev_warn(&cldev->dev, "not in correct state %s[%d]\n",
			 mei_wdt_state_str(wdt->state), wdt->state);

out:
	if (!completion_done(&wdt->response))
		complete(&wdt->response);
}

/*
 * mei_wdt_notif - callback for event notification
 *
 * @cldev: bus device
 */
static void mei_wdt_notif(struct mei_cl_device *cldev)
{
	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);

	if (wdt->state != MEI_WDT_NOT_REQUIRED)
		return;

	mei_wdt_register(wdt);
}

#if IS_ENABLED(CONFIG_DEBUG_FS)

static ssize_t mei_dbgfs_read_activation(struct file *file, char __user *ubuf,
					size_t cnt, loff_t *ppos)
{
	struct mei_wdt *wdt = file->private_data;
	const size_t bufsz = 32;
	char buf[32];
	ssize_t pos;

	mutex_lock(&wdt->reg_lock);
	pos = scnprintf(buf, bufsz, "%s\n",
		__mei_wdt_is_registered(wdt) ? "activated" : "deactivated");
	mutex_unlock(&wdt->reg_lock);

	return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
}

static const struct file_operations dbgfs_fops_activation = {
	.open    = simple_open,
	.read    = mei_dbgfs_read_activation,
	.llseek  = generic_file_llseek,
};

static ssize_t mei_dbgfs_read_state(struct file *file, char __user *ubuf,
				    size_t cnt, loff_t *ppos)
{
	struct mei_wdt *wdt = file->private_data;
	const size_t bufsz = 32;
	char buf[bufsz];
	ssize_t pos;

	pos = scnprintf(buf, bufsz, "state: %s\n",
			 mei_wdt_state_str(wdt->state));

	return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
}

static const struct file_operations dbgfs_fops_state = {
	.open = simple_open,
	.read = mei_dbgfs_read_state,
	.llseek = generic_file_llseek,
};

static void dbgfs_unregister(struct mei_wdt *wdt)
{
	debugfs_remove_recursive(wdt->dbgfs_dir);
	wdt->dbgfs_dir = NULL;
}

static int dbgfs_register(struct mei_wdt *wdt)
{
	struct dentry *dir, *f;

	dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
	if (!dir)
		return -ENOMEM;

	wdt->dbgfs_dir = dir;
	f = debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
	if (!f)
		goto err;

	f = debugfs_create_file("activation",  S_IRUSR,
				dir, wdt, &dbgfs_fops_activation);
	if (!f)
		goto err;

	return 0;
err:
	dbgfs_unregister(wdt);
	return -ENODEV;
}

#else

static inline void dbgfs_unregister(struct mei_wdt *wdt) {}

static inline int dbgfs_register(struct mei_wdt *wdt)
{
	return 0;
}
#endif /* CONFIG_DEBUG_FS */

static int mei_wdt_probe(struct mei_cl_device *cldev,
			 const struct mei_cl_device_id *id)
{
	struct mei_wdt *wdt;
	int ret;

	wdt = kzalloc(sizeof(struct mei_wdt), GFP_KERNEL);
	if (!wdt)
		return -ENOMEM;

	wdt->timeout = MEI_WDT_DEFAULT_TIMEOUT;
	wdt->state = MEI_WDT_PROBE;
	wdt->cldev = cldev;
	wdt->resp_required = mei_cldev_ver(cldev) > 0x1;
	mutex_init(&wdt->reg_lock);
	init_completion(&wdt->response);
	INIT_WORK(&wdt->unregister, mei_wdt_unregister_work);

	mei_cldev_set_drvdata(cldev, wdt);

	ret = mei_cldev_enable(cldev);
	if (ret < 0) {
		dev_err(&cldev->dev, "Could not enable cl device\n");
		goto err_out;
	}

	ret = mei_cldev_register_rx_cb(wdt->cldev, mei_wdt_rx);
	if (ret) {
		dev_err(&cldev->dev, "Could not reg rx event ret=%d\n", ret);
		goto err_disable;
	}

	ret = mei_cldev_register_notif_cb(wdt->cldev, mei_wdt_notif);
	/* on legacy devices notification is not supported
	 */
	if (ret && ret != -EOPNOTSUPP) {
		dev_err(&cldev->dev, "Could not reg notif event ret=%d\n", ret);
		goto err_disable;
	}

	wd_info.firmware_version = mei_cldev_ver(cldev);

	if (wdt->resp_required)
		ret = mei_wdt_ping(wdt);
	else
		ret = mei_wdt_register(wdt);

	if (ret)
		goto err_disable;

	if (dbgfs_register(wdt))
		dev_warn(&cldev->dev, "cannot register debugfs\n");

	return 0;

err_disable:
	mei_cldev_disable(cldev);

err_out:
	kfree(wdt);

	return ret;
}

static int mei_wdt_remove(struct mei_cl_device *cldev)
{
	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);

	/* Free the caller in case of fw initiated or unexpected reset */
	if (!completion_done(&wdt->response))
		complete(&wdt->response);

	cancel_work_sync(&wdt->unregister);

	mei_wdt_unregister(wdt);

	mei_cldev_disable(cldev);

	dbgfs_unregister(wdt);

	kfree(wdt);

	return 0;
}

#define MEI_UUID_WD UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, \
			    0x89, 0x9D, 0xA9, 0x15, 0x14, 0xCB, 0x32, 0xAB)

static const struct mei_cl_device_id mei_wdt_tbl[] = {
	{ .uuid = MEI_UUID_WD, .version = MEI_CL_VERSION_ANY },
	/* required last entry */
	{ }
};
MODULE_DEVICE_TABLE(mei, mei_wdt_tbl);

static struct mei_cl_driver mei_wdt_driver = {
	.id_table = mei_wdt_tbl,
	.name = KBUILD_MODNAME,

	.probe = mei_wdt_probe,
	.remove = mei_wdt_remove,
};

module_mei_cl_driver(mei_wdt_driver);

MODULE_AUTHOR("Intel Corporation");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog");
OpenPOWER on IntegriCloud