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1/*
2 * Intel Management Engine Interface (Intel MEI) Linux driver
3 * Copyright (c) 2015, Intel Corporation.
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms and conditions of the GNU General Public License,
7 * version 2, as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
12 * more details.
13 */
14
15#include <linux/module.h>
16#include <linux/slab.h>
17#include <linux/interrupt.h>
18#include <linux/debugfs.h>
19#include <linux/completion.h>
20#include <linux/watchdog.h>
21
22#include <linux/uuid.h>
23#include <linux/mei_cl_bus.h>
24
25/*
26 * iAMT Watchdog Device
27 */
28#define INTEL_AMT_WATCHDOG_ID "iamt_wdt"
29
30#define MEI_WDT_DEFAULT_TIMEOUT 120 /* seconds */
31#define MEI_WDT_MIN_TIMEOUT 120 /* seconds */
32#define MEI_WDT_MAX_TIMEOUT 65535 /* seconds */
33
34/* Commands */
35#define MEI_MANAGEMENT_CONTROL 0x02
36
37/* MEI Management Control version number */
38#define MEI_MC_VERSION_NUMBER 0x10
39
40/* Sub Commands */
41#define MEI_MC_START_WD_TIMER_REQ 0x13
42#define MEI_MC_START_WD_TIMER_RES 0x83
43#define MEI_WDT_STATUS_SUCCESS 0
44#define MEI_WDT_WDSTATE_NOT_REQUIRED 0x1
45#define MEI_MC_STOP_WD_TIMER_REQ 0x14
46
47/**
48 * enum mei_wdt_state - internal watchdog state
49 *
50 * @MEI_WDT_PROBE: wd in probing stage
51 * @MEI_WDT_IDLE: wd is idle and not opened
52 * @MEI_WDT_START: wd was opened, start was called
53 * @MEI_WDT_RUNNING: wd is expecting keep alive pings
54 * @MEI_WDT_STOPPING: wd is stopping and will move to IDLE
55 * @MEI_WDT_NOT_REQUIRED: wd device is not required
56 */
57enum mei_wdt_state {
58 MEI_WDT_PROBE,
59 MEI_WDT_IDLE,
60 MEI_WDT_START,
61 MEI_WDT_RUNNING,
62 MEI_WDT_STOPPING,
63 MEI_WDT_NOT_REQUIRED,
64};
65
66static const char *mei_wdt_state_str(enum mei_wdt_state state)
67{
68 switch (state) {
69 case MEI_WDT_PROBE:
70 return "PROBE";
71 case MEI_WDT_IDLE:
72 return "IDLE";
73 case MEI_WDT_START:
74 return "START";
75 case MEI_WDT_RUNNING:
76 return "RUNNING";
77 case MEI_WDT_STOPPING:
78 return "STOPPING";
79 case MEI_WDT_NOT_REQUIRED:
80 return "NOT_REQUIRED";
81 default:
82 return "unknown";
83 }
84}
85
86/**
87 * struct mei_wdt - mei watchdog driver
88 * @wdd: watchdog device
89 *
90 * @cldev: mei watchdog client device
91 * @state: watchdog internal state
92 * @resp_required: ping required response
93 * @response: ping response completion
94 * @unregister: unregister worker
95 * @reg_lock: watchdog device registration lock
96 * @timeout: watchdog current timeout
97 *
98 * @dbgfs_dir: debugfs dir entry
99 */
100struct mei_wdt {
101 struct watchdog_device wdd;
102
103 struct mei_cl_device *cldev;
104 enum mei_wdt_state state;
105 bool resp_required;
106 struct completion response;
107 struct work_struct unregister;
108 struct mutex reg_lock;
109 u16 timeout;
110
111#if IS_ENABLED(CONFIG_DEBUG_FS)
112 struct dentry *dbgfs_dir;
113#endif /* CONFIG_DEBUG_FS */
114};
115
116/*
117 * struct mei_mc_hdr - Management Control Command Header
118 *
119 * @command: Management Control (0x2)
120 * @bytecount: Number of bytes in the message beyond this byte
121 * @subcommand: Management Control Subcommand
122 * @versionnumber: Management Control Version (0x10)
123 */
124struct mei_mc_hdr {
125 u8 command;
126 u8 bytecount;
127 u8 subcommand;
128 u8 versionnumber;
129};
130
131/**
132 * struct mei_wdt_start_request watchdog start/ping
133 *
134 * @hdr: Management Control Command Header
135 * @timeout: timeout value
136 * @reserved: reserved (legacy)
137 */
138struct mei_wdt_start_request {
139 struct mei_mc_hdr hdr;
140 u16 timeout;
141 u8 reserved[17];
142} __packed;
143
144/**
145 * struct mei_wdt_start_response watchdog start/ping response
146 *
147 * @hdr: Management Control Command Header
148 * @status: operation status
149 * @wdstate: watchdog status bit mask
150 */
151struct mei_wdt_start_response {
152 struct mei_mc_hdr hdr;
153 u8 status;
154 u8 wdstate;
155} __packed;
156
157/**
158 * struct mei_wdt_stop_request - watchdog stop
159 *
160 * @hdr: Management Control Command Header
161 */
162struct mei_wdt_stop_request {
163 struct mei_mc_hdr hdr;
164} __packed;
165
166/**
167 * mei_wdt_ping - send wd start/ping command
168 *
169 * @wdt: mei watchdog device
170 *
171 * Return: 0 on success,
172 * negative errno code on failure
173 */
174static int mei_wdt_ping(struct mei_wdt *wdt)
175{
176 struct mei_wdt_start_request req;
177 const size_t req_len = sizeof(req);
178 int ret;
179
180 memset(&req, 0, req_len);
181 req.hdr.command = MEI_MANAGEMENT_CONTROL;
182 req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
183 req.hdr.subcommand = MEI_MC_START_WD_TIMER_REQ;
184 req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
185 req.timeout = wdt->timeout;
186
187 ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
188 if (ret < 0)
189 return ret;
190
191 return 0;
192}
193
194/**
195 * mei_wdt_stop - send wd stop command
196 *
197 * @wdt: mei watchdog device
198 *
199 * Return: 0 on success,
200 * negative errno code on failure
201 */
202static int mei_wdt_stop(struct mei_wdt *wdt)
203{
204 struct mei_wdt_stop_request req;
205 const size_t req_len = sizeof(req);
206 int ret;
207
208 memset(&req, 0, req_len);
209 req.hdr.command = MEI_MANAGEMENT_CONTROL;
210 req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
211 req.hdr.subcommand = MEI_MC_STOP_WD_TIMER_REQ;
212 req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
213
214 ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
215 if (ret < 0)
216 return ret;
217
218 return 0;
219}
220
221/**
222 * mei_wdt_ops_start - wd start command from the watchdog core.
223 *
224 * @wdd: watchdog device
225 *
226 * Return: 0 on success or -ENODEV;
227 */
228static int mei_wdt_ops_start(struct watchdog_device *wdd)
229{
230 struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
231
232 wdt->state = MEI_WDT_START;
233 wdd->timeout = wdt->timeout;
234 return 0;
235}
236
237/**
238 * mei_wdt_ops_stop - wd stop command from the watchdog core.
239 *
240 * @wdd: watchdog device
241 *
242 * Return: 0 if success, negative errno code for failure
243 */
244static int mei_wdt_ops_stop(struct watchdog_device *wdd)
245{
246 struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
247 int ret;
248
249 if (wdt->state != MEI_WDT_RUNNING)
250 return 0;
251
252 wdt->state = MEI_WDT_STOPPING;
253
254 ret = mei_wdt_stop(wdt);
255 if (ret)
256 return ret;
257
258 wdt->state = MEI_WDT_IDLE;
259
260 return 0;
261}
262
263/**
264 * mei_wdt_ops_ping - wd ping command from the watchdog core.
265 *
266 * @wdd: watchdog device
267 *
268 * Return: 0 if success, negative errno code on failure
269 */
270static int mei_wdt_ops_ping(struct watchdog_device *wdd)
271{
272 struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
273 int ret;
274
275 if (wdt->state != MEI_WDT_START && wdt->state != MEI_WDT_RUNNING)
276 return 0;
277
278 if (wdt->resp_required)
279 init_completion(&wdt->response);
280
281 wdt->state = MEI_WDT_RUNNING;
282 ret = mei_wdt_ping(wdt);
283 if (ret)
284 return ret;
285
286 if (wdt->resp_required)
287 ret = wait_for_completion_killable(&wdt->response);
288
289 return ret;
290}
291
292/**
293 * mei_wdt_ops_set_timeout - wd set timeout command from the watchdog core.
294 *
295 * @wdd: watchdog device
296 * @timeout: timeout value to set
297 *
298 * Return: 0 if success, negative errno code for failure
299 */
300static int mei_wdt_ops_set_timeout(struct watchdog_device *wdd,
301 unsigned int timeout)
302{
303
304 struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
305
306 /* valid value is already checked by the caller */
307 wdt->timeout = timeout;
308 wdd->timeout = timeout;
309
310 return 0;
311}
312
313static const struct watchdog_ops wd_ops = {
314 .owner = THIS_MODULE,
315 .start = mei_wdt_ops_start,
316 .stop = mei_wdt_ops_stop,
317 .ping = mei_wdt_ops_ping,
318 .set_timeout = mei_wdt_ops_set_timeout,
319};
320
321/* not const as the firmware_version field need to be retrieved */
322static struct watchdog_info wd_info = {
323 .identity = INTEL_AMT_WATCHDOG_ID,
324 .options = WDIOF_KEEPALIVEPING |
325 WDIOF_SETTIMEOUT |
326 WDIOF_ALARMONLY,
327};
328
329/**
330 * __mei_wdt_is_registered - check if wdt is registered
331 *
332 * @wdt: mei watchdog device
333 *
334 * Return: true if the wdt is registered with the watchdog subsystem
335 * Locking: should be called under wdt->reg_lock
336 */
337static inline bool __mei_wdt_is_registered(struct mei_wdt *wdt)
338{
339 return !!watchdog_get_drvdata(&wdt->wdd);
340}
341
342/**
343 * mei_wdt_unregister - unregister from the watchdog subsystem
344 *
345 * @wdt: mei watchdog device
346 */
347static void mei_wdt_unregister(struct mei_wdt *wdt)
348{
349 mutex_lock(&wdt->reg_lock);
350
351 if (__mei_wdt_is_registered(wdt)) {
352 watchdog_unregister_device(&wdt->wdd);
353 watchdog_set_drvdata(&wdt->wdd, NULL);
354 memset(&wdt->wdd, 0, sizeof(wdt->wdd));
355 }
356
357 mutex_unlock(&wdt->reg_lock);
358}
359
360/**
361 * mei_wdt_register - register with the watchdog subsystem
362 *
363 * @wdt: mei watchdog device
364 *
365 * Return: 0 if success, negative errno code for failure
366 */
367static int mei_wdt_register(struct mei_wdt *wdt)
368{
369 struct device *dev;
370 int ret;
371
372 if (!wdt || !wdt->cldev)
373 return -EINVAL;
374
375 dev = &wdt->cldev->dev;
376
377 mutex_lock(&wdt->reg_lock);
378
379 if (__mei_wdt_is_registered(wdt)) {
380 ret = 0;
381 goto out;
382 }
383
384 wdt->wdd.info = &wd_info;
385 wdt->wdd.ops = &wd_ops;
386 wdt->wdd.parent = dev;
387 wdt->wdd.timeout = MEI_WDT_DEFAULT_TIMEOUT;
388 wdt->wdd.min_timeout = MEI_WDT_MIN_TIMEOUT;
389 wdt->wdd.max_timeout = MEI_WDT_MAX_TIMEOUT;
390
391 watchdog_set_drvdata(&wdt->wdd, wdt);
392 watchdog_stop_on_reboot(&wdt->wdd);
393
394 ret = watchdog_register_device(&wdt->wdd);
395 if (ret) {
396 dev_err(dev, "unable to register watchdog device = %d.\n", ret);
397 watchdog_set_drvdata(&wdt->wdd, NULL);
398 }
399
400 wdt->state = MEI_WDT_IDLE;
401
402out:
403 mutex_unlock(&wdt->reg_lock);
404 return ret;
405}
406
407static void mei_wdt_unregister_work(struct work_struct *work)
408{
409 struct mei_wdt *wdt = container_of(work, struct mei_wdt, unregister);
410
411 mei_wdt_unregister(wdt);
412}
413
414/**
415 * mei_wdt_rx - callback for data receive
416 *
417 * @cldev: bus device
418 */
419static void mei_wdt_rx(struct mei_cl_device *cldev)
420{
421 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
422 struct mei_wdt_start_response res;
423 const size_t res_len = sizeof(res);
424 int ret;
425
426 ret = mei_cldev_recv(wdt->cldev, (u8 *)&res, res_len);
427 if (ret < 0) {
428 dev_err(&cldev->dev, "failure in recv %d\n", ret);
429 return;
430 }
431
432 /* Empty response can be sent on stop */
433 if (ret == 0)
434 return;
435
436 if (ret < sizeof(struct mei_mc_hdr)) {
437 dev_err(&cldev->dev, "recv small data %d\n", ret);
438 return;
439 }
440
441 if (res.hdr.command != MEI_MANAGEMENT_CONTROL ||
442 res.hdr.versionnumber != MEI_MC_VERSION_NUMBER) {
443 dev_err(&cldev->dev, "wrong command received\n");
444 return;
445 }
446
447 if (res.hdr.subcommand != MEI_MC_START_WD_TIMER_RES) {
448 dev_warn(&cldev->dev, "unsupported command %d :%s[%d]\n",
449 res.hdr.subcommand,
450 mei_wdt_state_str(wdt->state),
451 wdt->state);
452 return;
453 }
454
455 /* Run the unregistration in a worker as this can be
456 * run only after ping completion, otherwise the flow will
457 * deadlock on watchdog core mutex.
458 */
459 if (wdt->state == MEI_WDT_RUNNING) {
460 if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
461 wdt->state = MEI_WDT_NOT_REQUIRED;
462 schedule_work(&wdt->unregister);
463 }
464 goto out;
465 }
466
467 if (wdt->state == MEI_WDT_PROBE) {
468 if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
469 wdt->state = MEI_WDT_NOT_REQUIRED;
470 } else {
471 /* stop the watchdog and register watchdog device */
472 mei_wdt_stop(wdt);
473 mei_wdt_register(wdt);
474 }
475 return;
476 }
477
478 dev_warn(&cldev->dev, "not in correct state %s[%d]\n",
479 mei_wdt_state_str(wdt->state), wdt->state);
480
481out:
482 if (!completion_done(&wdt->response))
483 complete(&wdt->response);
484}
485
486/*
487 * mei_wdt_notif - callback for event notification
488 *
489 * @cldev: bus device
490 */
491static void mei_wdt_notif(struct mei_cl_device *cldev)
492{
493 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
494
495 if (wdt->state != MEI_WDT_NOT_REQUIRED)
496 return;
497
498 mei_wdt_register(wdt);
499}
500
501#if IS_ENABLED(CONFIG_DEBUG_FS)
502
503static ssize_t mei_dbgfs_read_activation(struct file *file, char __user *ubuf,
504 size_t cnt, loff_t *ppos)
505{
506 struct mei_wdt *wdt = file->private_data;
507 const size_t bufsz = 32;
508 char buf[32];
509 ssize_t pos;
510
511 mutex_lock(&wdt->reg_lock);
512 pos = scnprintf(buf, bufsz, "%s\n",
513 __mei_wdt_is_registered(wdt) ? "activated" : "deactivated");
514 mutex_unlock(&wdt->reg_lock);
515
516 return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
517}
518
519static const struct file_operations dbgfs_fops_activation = {
520 .open = simple_open,
521 .read = mei_dbgfs_read_activation,
522 .llseek = generic_file_llseek,
523};
524
525static ssize_t mei_dbgfs_read_state(struct file *file, char __user *ubuf,
526 size_t cnt, loff_t *ppos)
527{
528 struct mei_wdt *wdt = file->private_data;
529 const size_t bufsz = 32;
530 char buf[bufsz];
531 ssize_t pos;
532
533 pos = scnprintf(buf, bufsz, "state: %s\n",
534 mei_wdt_state_str(wdt->state));
535
536 return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
537}
538
539static const struct file_operations dbgfs_fops_state = {
540 .open = simple_open,
541 .read = mei_dbgfs_read_state,
542 .llseek = generic_file_llseek,
543};
544
545static void dbgfs_unregister(struct mei_wdt *wdt)
546{
547 debugfs_remove_recursive(wdt->dbgfs_dir);
548 wdt->dbgfs_dir = NULL;
549}
550
551static int dbgfs_register(struct mei_wdt *wdt)
552{
553 struct dentry *dir, *f;
554
555 dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
556 if (!dir)
557 return -ENOMEM;
558
559 wdt->dbgfs_dir = dir;
560 f = debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
561 if (!f)
562 goto err;
563
564 f = debugfs_create_file("activation", S_IRUSR,
565 dir, wdt, &dbgfs_fops_activation);
566 if (!f)
567 goto err;
568
569 return 0;
570err:
571 dbgfs_unregister(wdt);
572 return -ENODEV;
573}
574
575#else
576
577static inline void dbgfs_unregister(struct mei_wdt *wdt) {}
578
579static inline int dbgfs_register(struct mei_wdt *wdt)
580{
581 return 0;
582}
583#endif /* CONFIG_DEBUG_FS */
584
585static int mei_wdt_probe(struct mei_cl_device *cldev,
586 const struct mei_cl_device_id *id)
587{
588 struct mei_wdt *wdt;
589 int ret;
590
591 wdt = kzalloc(sizeof(struct mei_wdt), GFP_KERNEL);
592 if (!wdt)
593 return -ENOMEM;
594
595 wdt->timeout = MEI_WDT_DEFAULT_TIMEOUT;
596 wdt->state = MEI_WDT_PROBE;
597 wdt->cldev = cldev;
598 wdt->resp_required = mei_cldev_ver(cldev) > 0x1;
599 mutex_init(&wdt->reg_lock);
600 init_completion(&wdt->response);
601 INIT_WORK(&wdt->unregister, mei_wdt_unregister_work);
602
603 mei_cldev_set_drvdata(cldev, wdt);
604
605 ret = mei_cldev_enable(cldev);
606 if (ret < 0) {
607 dev_err(&cldev->dev, "Could not enable cl device\n");
608 goto err_out;
609 }
610
611 ret = mei_cldev_register_rx_cb(wdt->cldev, mei_wdt_rx);
612 if (ret) {
613 dev_err(&cldev->dev, "Could not reg rx event ret=%d\n", ret);
614 goto err_disable;
615 }
616
617 ret = mei_cldev_register_notif_cb(wdt->cldev, mei_wdt_notif);
618 /* on legacy devices notification is not supported
619 */
620 if (ret && ret != -EOPNOTSUPP) {
621 dev_err(&cldev->dev, "Could not reg notif event ret=%d\n", ret);
622 goto err_disable;
623 }
624
625 wd_info.firmware_version = mei_cldev_ver(cldev);
626
627 if (wdt->resp_required)
628 ret = mei_wdt_ping(wdt);
629 else
630 ret = mei_wdt_register(wdt);
631
632 if (ret)
633 goto err_disable;
634
635 if (dbgfs_register(wdt))
636 dev_warn(&cldev->dev, "cannot register debugfs\n");
637
638 return 0;
639
640err_disable:
641 mei_cldev_disable(cldev);
642
643err_out:
644 kfree(wdt);
645
646 return ret;
647}
648
649static int mei_wdt_remove(struct mei_cl_device *cldev)
650{
651 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
652
653 /* Free the caller in case of fw initiated or unexpected reset */
654 if (!completion_done(&wdt->response))
655 complete(&wdt->response);
656
657 cancel_work_sync(&wdt->unregister);
658
659 mei_wdt_unregister(wdt);
660
661 mei_cldev_disable(cldev);
662
663 dbgfs_unregister(wdt);
664
665 kfree(wdt);
666
667 return 0;
668}
669
670#define MEI_UUID_WD UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, \
671 0x89, 0x9D, 0xA9, 0x15, 0x14, 0xCB, 0x32, 0xAB)
672
673static struct mei_cl_device_id mei_wdt_tbl[] = {
674 { .uuid = MEI_UUID_WD, .version = MEI_CL_VERSION_ANY },
675 /* required last entry */
676 { }
677};
678MODULE_DEVICE_TABLE(mei, mei_wdt_tbl);
679
680static struct mei_cl_driver mei_wdt_driver = {
681 .id_table = mei_wdt_tbl,
682 .name = KBUILD_MODNAME,
683
684 .probe = mei_wdt_probe,
685 .remove = mei_wdt_remove,
686};
687
688module_mei_cl_driver(mei_wdt_driver);
689
690MODULE_AUTHOR("Intel Corporation");
691MODULE_LICENSE("GPL");
692MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog");