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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Intel Management Engine Interface (Intel MEI) Linux driver
4 * Copyright (c) 2015, Intel Corporation.
5 */
6
7#include <linux/module.h>
8#include <linux/slab.h>
9#include <linux/interrupt.h>
10#include <linux/debugfs.h>
11#include <linux/completion.h>
12#include <linux/watchdog.h>
13
14#include <linux/uuid.h>
15#include <linux/mei_cl_bus.h>
16
17/*
18 * iAMT Watchdog Device
19 */
20#define INTEL_AMT_WATCHDOG_ID "iamt_wdt"
21
22#define MEI_WDT_DEFAULT_TIMEOUT 120 /* seconds */
23#define MEI_WDT_MIN_TIMEOUT 120 /* seconds */
24#define MEI_WDT_MAX_TIMEOUT 65535 /* seconds */
25
26/* Commands */
27#define MEI_MANAGEMENT_CONTROL 0x02
28
29/* MEI Management Control version number */
30#define MEI_MC_VERSION_NUMBER 0x10
31
32/* Sub Commands */
33#define MEI_MC_START_WD_TIMER_REQ 0x13
34#define MEI_MC_START_WD_TIMER_RES 0x83
35#define MEI_WDT_STATUS_SUCCESS 0
36#define MEI_WDT_WDSTATE_NOT_REQUIRED 0x1
37#define MEI_MC_STOP_WD_TIMER_REQ 0x14
38
39/**
40 * enum mei_wdt_state - internal watchdog state
41 *
42 * @MEI_WDT_PROBE: wd in probing stage
43 * @MEI_WDT_IDLE: wd is idle and not opened
44 * @MEI_WDT_START: wd was opened, start was called
45 * @MEI_WDT_RUNNING: wd is expecting keep alive pings
46 * @MEI_WDT_STOPPING: wd is stopping and will move to IDLE
47 * @MEI_WDT_NOT_REQUIRED: wd device is not required
48 */
49enum mei_wdt_state {
50 MEI_WDT_PROBE,
51 MEI_WDT_IDLE,
52 MEI_WDT_START,
53 MEI_WDT_RUNNING,
54 MEI_WDT_STOPPING,
55 MEI_WDT_NOT_REQUIRED,
56};
57
58static const char *mei_wdt_state_str(enum mei_wdt_state state)
59{
60 switch (state) {
61 case MEI_WDT_PROBE:
62 return "PROBE";
63 case MEI_WDT_IDLE:
64 return "IDLE";
65 case MEI_WDT_START:
66 return "START";
67 case MEI_WDT_RUNNING:
68 return "RUNNING";
69 case MEI_WDT_STOPPING:
70 return "STOPPING";
71 case MEI_WDT_NOT_REQUIRED:
72 return "NOT_REQUIRED";
73 default:
74 return "unknown";
75 }
76}
77
78/**
79 * struct mei_wdt - mei watchdog driver
80 * @wdd: watchdog device
81 *
82 * @cldev: mei watchdog client device
83 * @state: watchdog internal state
84 * @resp_required: ping required response
85 * @response: ping response completion
86 * @unregister: unregister worker
87 * @reg_lock: watchdog device registration lock
88 * @timeout: watchdog current timeout
89 *
90 * @dbgfs_dir: debugfs dir entry
91 */
92struct mei_wdt {
93 struct watchdog_device wdd;
94
95 struct mei_cl_device *cldev;
96 enum mei_wdt_state state;
97 bool resp_required;
98 struct completion response;
99 struct work_struct unregister;
100 struct mutex reg_lock;
101 u16 timeout;
102
103#if IS_ENABLED(CONFIG_DEBUG_FS)
104 struct dentry *dbgfs_dir;
105#endif /* CONFIG_DEBUG_FS */
106};
107
108/**
109 * struct mei_mc_hdr - Management Control Command Header
110 *
111 * @command: Management Control (0x2)
112 * @bytecount: Number of bytes in the message beyond this byte
113 * @subcommand: Management Control Subcommand
114 * @versionnumber: Management Control Version (0x10)
115 */
116struct mei_mc_hdr {
117 u8 command;
118 u8 bytecount;
119 u8 subcommand;
120 u8 versionnumber;
121};
122
123/**
124 * struct mei_wdt_start_request - watchdog start/ping
125 *
126 * @hdr: Management Control Command Header
127 * @timeout: timeout value
128 * @reserved: reserved (legacy)
129 */
130struct mei_wdt_start_request {
131 struct mei_mc_hdr hdr;
132 u16 timeout;
133 u8 reserved[17];
134} __packed;
135
136/**
137 * struct mei_wdt_start_response - watchdog start/ping response
138 *
139 * @hdr: Management Control Command Header
140 * @status: operation status
141 * @wdstate: watchdog status bit mask
142 */
143struct mei_wdt_start_response {
144 struct mei_mc_hdr hdr;
145 u8 status;
146 u8 wdstate;
147} __packed;
148
149/**
150 * struct mei_wdt_stop_request - watchdog stop
151 *
152 * @hdr: Management Control Command Header
153 */
154struct mei_wdt_stop_request {
155 struct mei_mc_hdr hdr;
156} __packed;
157
158/**
159 * mei_wdt_ping - send wd start/ping command
160 *
161 * @wdt: mei watchdog device
162 *
163 * Return: 0 on success,
164 * negative errno code on failure
165 */
166static int mei_wdt_ping(struct mei_wdt *wdt)
167{
168 struct mei_wdt_start_request req;
169 const size_t req_len = sizeof(req);
170 int ret;
171
172 memset(&req, 0, req_len);
173 req.hdr.command = MEI_MANAGEMENT_CONTROL;
174 req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
175 req.hdr.subcommand = MEI_MC_START_WD_TIMER_REQ;
176 req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
177 req.timeout = wdt->timeout;
178
179 ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
180 if (ret < 0)
181 return ret;
182
183 return 0;
184}
185
186/**
187 * mei_wdt_stop - send wd stop command
188 *
189 * @wdt: mei watchdog device
190 *
191 * Return: 0 on success,
192 * negative errno code on failure
193 */
194static int mei_wdt_stop(struct mei_wdt *wdt)
195{
196 struct mei_wdt_stop_request req;
197 const size_t req_len = sizeof(req);
198 int ret;
199
200 memset(&req, 0, req_len);
201 req.hdr.command = MEI_MANAGEMENT_CONTROL;
202 req.hdr.bytecount = req_len - offsetof(struct mei_mc_hdr, subcommand);
203 req.hdr.subcommand = MEI_MC_STOP_WD_TIMER_REQ;
204 req.hdr.versionnumber = MEI_MC_VERSION_NUMBER;
205
206 ret = mei_cldev_send(wdt->cldev, (u8 *)&req, req_len);
207 if (ret < 0)
208 return ret;
209
210 return 0;
211}
212
213/**
214 * mei_wdt_ops_start - wd start command from the watchdog core.
215 *
216 * @wdd: watchdog device
217 *
218 * Return: 0 on success or -ENODEV;
219 */
220static int mei_wdt_ops_start(struct watchdog_device *wdd)
221{
222 struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
223
224 wdt->state = MEI_WDT_START;
225 wdd->timeout = wdt->timeout;
226 return 0;
227}
228
229/**
230 * mei_wdt_ops_stop - wd stop command from the watchdog core.
231 *
232 * @wdd: watchdog device
233 *
234 * Return: 0 if success, negative errno code for failure
235 */
236static int mei_wdt_ops_stop(struct watchdog_device *wdd)
237{
238 struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
239 int ret;
240
241 if (wdt->state != MEI_WDT_RUNNING)
242 return 0;
243
244 wdt->state = MEI_WDT_STOPPING;
245
246 ret = mei_wdt_stop(wdt);
247 if (ret)
248 return ret;
249
250 wdt->state = MEI_WDT_IDLE;
251
252 return 0;
253}
254
255/**
256 * mei_wdt_ops_ping - wd ping command from the watchdog core.
257 *
258 * @wdd: watchdog device
259 *
260 * Return: 0 if success, negative errno code on failure
261 */
262static int mei_wdt_ops_ping(struct watchdog_device *wdd)
263{
264 struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
265 int ret;
266
267 if (wdt->state != MEI_WDT_START && wdt->state != MEI_WDT_RUNNING)
268 return 0;
269
270 if (wdt->resp_required)
271 init_completion(&wdt->response);
272
273 wdt->state = MEI_WDT_RUNNING;
274 ret = mei_wdt_ping(wdt);
275 if (ret)
276 return ret;
277
278 if (wdt->resp_required)
279 ret = wait_for_completion_killable(&wdt->response);
280
281 return ret;
282}
283
284/**
285 * mei_wdt_ops_set_timeout - wd set timeout command from the watchdog core.
286 *
287 * @wdd: watchdog device
288 * @timeout: timeout value to set
289 *
290 * Return: 0 if success, negative errno code for failure
291 */
292static int mei_wdt_ops_set_timeout(struct watchdog_device *wdd,
293 unsigned int timeout)
294{
295
296 struct mei_wdt *wdt = watchdog_get_drvdata(wdd);
297
298 /* valid value is already checked by the caller */
299 wdt->timeout = timeout;
300 wdd->timeout = timeout;
301
302 return 0;
303}
304
305static const struct watchdog_ops wd_ops = {
306 .owner = THIS_MODULE,
307 .start = mei_wdt_ops_start,
308 .stop = mei_wdt_ops_stop,
309 .ping = mei_wdt_ops_ping,
310 .set_timeout = mei_wdt_ops_set_timeout,
311};
312
313/* not const as the firmware_version field need to be retrieved */
314static struct watchdog_info wd_info = {
315 .identity = INTEL_AMT_WATCHDOG_ID,
316 .options = WDIOF_KEEPALIVEPING |
317 WDIOF_SETTIMEOUT |
318 WDIOF_ALARMONLY,
319};
320
321/**
322 * __mei_wdt_is_registered - check if wdt is registered
323 *
324 * @wdt: mei watchdog device
325 *
326 * Return: true if the wdt is registered with the watchdog subsystem
327 * Locking: should be called under wdt->reg_lock
328 */
329static inline bool __mei_wdt_is_registered(struct mei_wdt *wdt)
330{
331 return !!watchdog_get_drvdata(&wdt->wdd);
332}
333
334/**
335 * mei_wdt_unregister - unregister from the watchdog subsystem
336 *
337 * @wdt: mei watchdog device
338 */
339static void mei_wdt_unregister(struct mei_wdt *wdt)
340{
341 mutex_lock(&wdt->reg_lock);
342
343 if (__mei_wdt_is_registered(wdt)) {
344 watchdog_unregister_device(&wdt->wdd);
345 watchdog_set_drvdata(&wdt->wdd, NULL);
346 memset(&wdt->wdd, 0, sizeof(wdt->wdd));
347 }
348
349 mutex_unlock(&wdt->reg_lock);
350}
351
352/**
353 * mei_wdt_register - register with the watchdog subsystem
354 *
355 * @wdt: mei watchdog device
356 *
357 * Return: 0 if success, negative errno code for failure
358 */
359static int mei_wdt_register(struct mei_wdt *wdt)
360{
361 struct device *dev;
362 int ret;
363
364 if (!wdt || !wdt->cldev)
365 return -EINVAL;
366
367 dev = &wdt->cldev->dev;
368
369 mutex_lock(&wdt->reg_lock);
370
371 if (__mei_wdt_is_registered(wdt)) {
372 ret = 0;
373 goto out;
374 }
375
376 wdt->wdd.info = &wd_info;
377 wdt->wdd.ops = &wd_ops;
378 wdt->wdd.parent = dev;
379 wdt->wdd.timeout = MEI_WDT_DEFAULT_TIMEOUT;
380 wdt->wdd.min_timeout = MEI_WDT_MIN_TIMEOUT;
381 wdt->wdd.max_timeout = MEI_WDT_MAX_TIMEOUT;
382
383 watchdog_set_drvdata(&wdt->wdd, wdt);
384 watchdog_stop_on_reboot(&wdt->wdd);
385 watchdog_stop_on_unregister(&wdt->wdd);
386
387 ret = watchdog_register_device(&wdt->wdd);
388 if (ret)
389 watchdog_set_drvdata(&wdt->wdd, NULL);
390
391 wdt->state = MEI_WDT_IDLE;
392
393out:
394 mutex_unlock(&wdt->reg_lock);
395 return ret;
396}
397
398static void mei_wdt_unregister_work(struct work_struct *work)
399{
400 struct mei_wdt *wdt = container_of(work, struct mei_wdt, unregister);
401
402 mei_wdt_unregister(wdt);
403}
404
405/**
406 * mei_wdt_rx - callback for data receive
407 *
408 * @cldev: bus device
409 */
410static void mei_wdt_rx(struct mei_cl_device *cldev)
411{
412 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
413 struct mei_wdt_start_response res;
414 const size_t res_len = sizeof(res);
415 int ret;
416
417 ret = mei_cldev_recv(wdt->cldev, (u8 *)&res, res_len);
418 if (ret < 0) {
419 dev_err(&cldev->dev, "failure in recv %d\n", ret);
420 return;
421 }
422
423 /* Empty response can be sent on stop */
424 if (ret == 0)
425 return;
426
427 if (ret < sizeof(struct mei_mc_hdr)) {
428 dev_err(&cldev->dev, "recv small data %d\n", ret);
429 return;
430 }
431
432 if (res.hdr.command != MEI_MANAGEMENT_CONTROL ||
433 res.hdr.versionnumber != MEI_MC_VERSION_NUMBER) {
434 dev_err(&cldev->dev, "wrong command received\n");
435 return;
436 }
437
438 if (res.hdr.subcommand != MEI_MC_START_WD_TIMER_RES) {
439 dev_warn(&cldev->dev, "unsupported command %d :%s[%d]\n",
440 res.hdr.subcommand,
441 mei_wdt_state_str(wdt->state),
442 wdt->state);
443 return;
444 }
445
446 /* Run the unregistration in a worker as this can be
447 * run only after ping completion, otherwise the flow will
448 * deadlock on watchdog core mutex.
449 */
450 if (wdt->state == MEI_WDT_RUNNING) {
451 if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
452 wdt->state = MEI_WDT_NOT_REQUIRED;
453 schedule_work(&wdt->unregister);
454 }
455 goto out;
456 }
457
458 if (wdt->state == MEI_WDT_PROBE) {
459 if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
460 wdt->state = MEI_WDT_NOT_REQUIRED;
461 } else {
462 /* stop the watchdog and register watchdog device */
463 mei_wdt_stop(wdt);
464 mei_wdt_register(wdt);
465 }
466 return;
467 }
468
469 dev_warn(&cldev->dev, "not in correct state %s[%d]\n",
470 mei_wdt_state_str(wdt->state), wdt->state);
471
472out:
473 if (!completion_done(&wdt->response))
474 complete(&wdt->response);
475}
476
477/**
478 * mei_wdt_notif - callback for event notification
479 *
480 * @cldev: bus device
481 */
482static void mei_wdt_notif(struct mei_cl_device *cldev)
483{
484 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
485
486 if (wdt->state != MEI_WDT_NOT_REQUIRED)
487 return;
488
489 mei_wdt_register(wdt);
490}
491
492#if IS_ENABLED(CONFIG_DEBUG_FS)
493
494static ssize_t mei_dbgfs_read_activation(struct file *file, char __user *ubuf,
495 size_t cnt, loff_t *ppos)
496{
497 struct mei_wdt *wdt = file->private_data;
498 const size_t bufsz = 32;
499 char buf[32];
500 ssize_t pos;
501
502 mutex_lock(&wdt->reg_lock);
503 pos = scnprintf(buf, bufsz, "%s\n",
504 __mei_wdt_is_registered(wdt) ? "activated" : "deactivated");
505 mutex_unlock(&wdt->reg_lock);
506
507 return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
508}
509
510static const struct file_operations dbgfs_fops_activation = {
511 .open = simple_open,
512 .read = mei_dbgfs_read_activation,
513 .llseek = generic_file_llseek,
514};
515
516static ssize_t mei_dbgfs_read_state(struct file *file, char __user *ubuf,
517 size_t cnt, loff_t *ppos)
518{
519 struct mei_wdt *wdt = file->private_data;
520 char buf[32];
521 ssize_t pos;
522
523 pos = scnprintf(buf, sizeof(buf), "state: %s\n",
524 mei_wdt_state_str(wdt->state));
525
526 return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
527}
528
529static const struct file_operations dbgfs_fops_state = {
530 .open = simple_open,
531 .read = mei_dbgfs_read_state,
532 .llseek = generic_file_llseek,
533};
534
535static void dbgfs_unregister(struct mei_wdt *wdt)
536{
537 debugfs_remove_recursive(wdt->dbgfs_dir);
538 wdt->dbgfs_dir = NULL;
539}
540
541static void dbgfs_register(struct mei_wdt *wdt)
542{
543 struct dentry *dir;
544
545 dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
546 wdt->dbgfs_dir = dir;
547
548 debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
549
550 debugfs_create_file("activation", S_IRUSR, dir, wdt,
551 &dbgfs_fops_activation);
552}
553
554#else
555
556static inline void dbgfs_unregister(struct mei_wdt *wdt) {}
557static inline void dbgfs_register(struct mei_wdt *wdt) {}
558#endif /* CONFIG_DEBUG_FS */
559
560static int mei_wdt_probe(struct mei_cl_device *cldev,
561 const struct mei_cl_device_id *id)
562{
563 struct mei_wdt *wdt;
564 int ret;
565
566 wdt = kzalloc(sizeof(struct mei_wdt), GFP_KERNEL);
567 if (!wdt)
568 return -ENOMEM;
569
570 wdt->timeout = MEI_WDT_DEFAULT_TIMEOUT;
571 wdt->state = MEI_WDT_PROBE;
572 wdt->cldev = cldev;
573 wdt->resp_required = mei_cldev_ver(cldev) > 0x1;
574 mutex_init(&wdt->reg_lock);
575 init_completion(&wdt->response);
576 INIT_WORK(&wdt->unregister, mei_wdt_unregister_work);
577
578 mei_cldev_set_drvdata(cldev, wdt);
579
580 ret = mei_cldev_enable(cldev);
581 if (ret < 0) {
582 dev_err(&cldev->dev, "Could not enable cl device\n");
583 goto err_out;
584 }
585
586 ret = mei_cldev_register_rx_cb(wdt->cldev, mei_wdt_rx);
587 if (ret) {
588 dev_err(&cldev->dev, "Could not reg rx event ret=%d\n", ret);
589 goto err_disable;
590 }
591
592 ret = mei_cldev_register_notif_cb(wdt->cldev, mei_wdt_notif);
593 /* on legacy devices notification is not supported
594 */
595 if (ret && ret != -EOPNOTSUPP) {
596 dev_err(&cldev->dev, "Could not reg notif event ret=%d\n", ret);
597 goto err_disable;
598 }
599
600 wd_info.firmware_version = mei_cldev_ver(cldev);
601
602 if (wdt->resp_required)
603 ret = mei_wdt_ping(wdt);
604 else
605 ret = mei_wdt_register(wdt);
606
607 if (ret)
608 goto err_disable;
609
610 dbgfs_register(wdt);
611
612 return 0;
613
614err_disable:
615 mei_cldev_disable(cldev);
616
617err_out:
618 kfree(wdt);
619
620 return ret;
621}
622
623static void mei_wdt_remove(struct mei_cl_device *cldev)
624{
625 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
626
627 /* Free the caller in case of fw initiated or unexpected reset */
628 if (!completion_done(&wdt->response))
629 complete(&wdt->response);
630
631 cancel_work_sync(&wdt->unregister);
632
633 mei_wdt_unregister(wdt);
634
635 mei_cldev_disable(cldev);
636
637 dbgfs_unregister(wdt);
638
639 kfree(wdt);
640}
641
642#define MEI_UUID_WD UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, \
643 0x89, 0x9D, 0xA9, 0x15, 0x14, 0xCB, 0x32, 0xAB)
644
645static const struct mei_cl_device_id mei_wdt_tbl[] = {
646 { .uuid = MEI_UUID_WD, .version = MEI_CL_VERSION_ANY },
647 /* required last entry */
648 { }
649};
650MODULE_DEVICE_TABLE(mei, mei_wdt_tbl);
651
652static struct mei_cl_driver mei_wdt_driver = {
653 .id_table = mei_wdt_tbl,
654 .name = KBUILD_MODNAME,
655
656 .probe = mei_wdt_probe,
657 .remove = mei_wdt_remove,
658};
659
660module_mei_cl_driver(mei_wdt_driver);
661
662MODULE_AUTHOR("Intel Corporation");
663MODULE_LICENSE("GPL v2");
664MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog");
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 ret = watchdog_register_device(&wdt->wdd);
393 if (ret) {
394 dev_err(dev, "unable to register watchdog device = %d.\n", ret);
395 watchdog_set_drvdata(&wdt->wdd, NULL);
396 }
397
398 wdt->state = MEI_WDT_IDLE;
399
400out:
401 mutex_unlock(&wdt->reg_lock);
402 return ret;
403}
404
405static void mei_wdt_unregister_work(struct work_struct *work)
406{
407 struct mei_wdt *wdt = container_of(work, struct mei_wdt, unregister);
408
409 mei_wdt_unregister(wdt);
410}
411
412/**
413 * mei_wdt_event_rx - callback for data receive
414 *
415 * @cldev: bus device
416 */
417static void mei_wdt_event_rx(struct mei_cl_device *cldev)
418{
419 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
420 struct mei_wdt_start_response res;
421 const size_t res_len = sizeof(res);
422 int ret;
423
424 ret = mei_cldev_recv(wdt->cldev, (u8 *)&res, res_len);
425 if (ret < 0) {
426 dev_err(&cldev->dev, "failure in recv %d\n", ret);
427 return;
428 }
429
430 /* Empty response can be sent on stop */
431 if (ret == 0)
432 return;
433
434 if (ret < sizeof(struct mei_mc_hdr)) {
435 dev_err(&cldev->dev, "recv small data %d\n", ret);
436 return;
437 }
438
439 if (res.hdr.command != MEI_MANAGEMENT_CONTROL ||
440 res.hdr.versionnumber != MEI_MC_VERSION_NUMBER) {
441 dev_err(&cldev->dev, "wrong command received\n");
442 return;
443 }
444
445 if (res.hdr.subcommand != MEI_MC_START_WD_TIMER_RES) {
446 dev_warn(&cldev->dev, "unsupported command %d :%s[%d]\n",
447 res.hdr.subcommand,
448 mei_wdt_state_str(wdt->state),
449 wdt->state);
450 return;
451 }
452
453 /* Run the unregistration in a worker as this can be
454 * run only after ping completion, otherwise the flow will
455 * deadlock on watchdog core mutex.
456 */
457 if (wdt->state == MEI_WDT_RUNNING) {
458 if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
459 wdt->state = MEI_WDT_NOT_REQUIRED;
460 schedule_work(&wdt->unregister);
461 }
462 goto out;
463 }
464
465 if (wdt->state == MEI_WDT_PROBE) {
466 if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
467 wdt->state = MEI_WDT_NOT_REQUIRED;
468 } else {
469 /* stop the watchdog and register watchdog device */
470 mei_wdt_stop(wdt);
471 mei_wdt_register(wdt);
472 }
473 return;
474 }
475
476 dev_warn(&cldev->dev, "not in correct state %s[%d]\n",
477 mei_wdt_state_str(wdt->state), wdt->state);
478
479out:
480 if (!completion_done(&wdt->response))
481 complete(&wdt->response);
482}
483
484/*
485 * mei_wdt_notify_event - callback for event notification
486 *
487 * @cldev: bus device
488 */
489static void mei_wdt_notify_event(struct mei_cl_device *cldev)
490{
491 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
492
493 if (wdt->state != MEI_WDT_NOT_REQUIRED)
494 return;
495
496 mei_wdt_register(wdt);
497}
498
499/**
500 * mei_wdt_event - callback for event receive
501 *
502 * @cldev: bus device
503 * @events: event mask
504 * @context: callback context
505 */
506static void mei_wdt_event(struct mei_cl_device *cldev,
507 u32 events, void *context)
508{
509 if (events & BIT(MEI_CL_EVENT_RX))
510 mei_wdt_event_rx(cldev);
511
512 if (events & BIT(MEI_CL_EVENT_NOTIF))
513 mei_wdt_notify_event(cldev);
514}
515
516#if IS_ENABLED(CONFIG_DEBUG_FS)
517
518static ssize_t mei_dbgfs_read_activation(struct file *file, char __user *ubuf,
519 size_t cnt, loff_t *ppos)
520{
521 struct mei_wdt *wdt = file->private_data;
522 const size_t bufsz = 32;
523 char buf[32];
524 ssize_t pos;
525
526 mutex_lock(&wdt->reg_lock);
527 pos = scnprintf(buf, bufsz, "%s\n",
528 __mei_wdt_is_registered(wdt) ? "activated" : "deactivated");
529 mutex_unlock(&wdt->reg_lock);
530
531 return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
532}
533
534static const struct file_operations dbgfs_fops_activation = {
535 .open = simple_open,
536 .read = mei_dbgfs_read_activation,
537 .llseek = generic_file_llseek,
538};
539
540static ssize_t mei_dbgfs_read_state(struct file *file, char __user *ubuf,
541 size_t cnt, loff_t *ppos)
542{
543 struct mei_wdt *wdt = file->private_data;
544 const size_t bufsz = 32;
545 char buf[bufsz];
546 ssize_t pos;
547
548 pos = scnprintf(buf, bufsz, "state: %s\n",
549 mei_wdt_state_str(wdt->state));
550
551 return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
552}
553
554static const struct file_operations dbgfs_fops_state = {
555 .open = simple_open,
556 .read = mei_dbgfs_read_state,
557 .llseek = generic_file_llseek,
558};
559
560static void dbgfs_unregister(struct mei_wdt *wdt)
561{
562 debugfs_remove_recursive(wdt->dbgfs_dir);
563 wdt->dbgfs_dir = NULL;
564}
565
566static int dbgfs_register(struct mei_wdt *wdt)
567{
568 struct dentry *dir, *f;
569
570 dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
571 if (!dir)
572 return -ENOMEM;
573
574 wdt->dbgfs_dir = dir;
575 f = debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
576 if (!f)
577 goto err;
578
579 f = debugfs_create_file("activation", S_IRUSR,
580 dir, wdt, &dbgfs_fops_activation);
581 if (!f)
582 goto err;
583
584 return 0;
585err:
586 dbgfs_unregister(wdt);
587 return -ENODEV;
588}
589
590#else
591
592static inline void dbgfs_unregister(struct mei_wdt *wdt) {}
593
594static inline int dbgfs_register(struct mei_wdt *wdt)
595{
596 return 0;
597}
598#endif /* CONFIG_DEBUG_FS */
599
600static int mei_wdt_probe(struct mei_cl_device *cldev,
601 const struct mei_cl_device_id *id)
602{
603 struct mei_wdt *wdt;
604 int ret;
605
606 wdt = kzalloc(sizeof(struct mei_wdt), GFP_KERNEL);
607 if (!wdt)
608 return -ENOMEM;
609
610 wdt->timeout = MEI_WDT_DEFAULT_TIMEOUT;
611 wdt->state = MEI_WDT_PROBE;
612 wdt->cldev = cldev;
613 wdt->resp_required = mei_cldev_ver(cldev) > 0x1;
614 mutex_init(&wdt->reg_lock);
615 init_completion(&wdt->response);
616 INIT_WORK(&wdt->unregister, mei_wdt_unregister_work);
617
618 mei_cldev_set_drvdata(cldev, wdt);
619
620 ret = mei_cldev_enable(cldev);
621 if (ret < 0) {
622 dev_err(&cldev->dev, "Could not enable cl device\n");
623 goto err_out;
624 }
625
626 ret = mei_cldev_register_event_cb(wdt->cldev,
627 BIT(MEI_CL_EVENT_RX) |
628 BIT(MEI_CL_EVENT_NOTIF),
629 mei_wdt_event, NULL);
630
631 /* on legacy devices notification is not supported
632 * this doesn't fail the registration for RX event
633 */
634 if (ret && ret != -EOPNOTSUPP) {
635 dev_err(&cldev->dev, "Could not register event ret=%d\n", ret);
636 goto err_disable;
637 }
638
639 wd_info.firmware_version = mei_cldev_ver(cldev);
640
641 if (wdt->resp_required)
642 ret = mei_wdt_ping(wdt);
643 else
644 ret = mei_wdt_register(wdt);
645
646 if (ret)
647 goto err_disable;
648
649 if (dbgfs_register(wdt))
650 dev_warn(&cldev->dev, "cannot register debugfs\n");
651
652 return 0;
653
654err_disable:
655 mei_cldev_disable(cldev);
656
657err_out:
658 kfree(wdt);
659
660 return ret;
661}
662
663static int mei_wdt_remove(struct mei_cl_device *cldev)
664{
665 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
666
667 /* Free the caller in case of fw initiated or unexpected reset */
668 if (!completion_done(&wdt->response))
669 complete(&wdt->response);
670
671 cancel_work_sync(&wdt->unregister);
672
673 mei_wdt_unregister(wdt);
674
675 mei_cldev_disable(cldev);
676
677 dbgfs_unregister(wdt);
678
679 kfree(wdt);
680
681 return 0;
682}
683
684#define MEI_UUID_WD UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, \
685 0x89, 0x9D, 0xA9, 0x15, 0x14, 0xCB, 0x32, 0xAB)
686
687static struct mei_cl_device_id mei_wdt_tbl[] = {
688 { .uuid = MEI_UUID_WD, .version = MEI_CL_VERSION_ANY },
689 /* required last entry */
690 { }
691};
692MODULE_DEVICE_TABLE(mei, mei_wdt_tbl);
693
694static struct mei_cl_driver mei_wdt_driver = {
695 .id_table = mei_wdt_tbl,
696 .name = KBUILD_MODNAME,
697
698 .probe = mei_wdt_probe,
699 .remove = mei_wdt_remove,
700};
701
702static int __init mei_wdt_init(void)
703{
704 int ret;
705
706 ret = mei_cldev_driver_register(&mei_wdt_driver);
707 if (ret) {
708 pr_err(KBUILD_MODNAME ": module registration failed\n");
709 return ret;
710 }
711 return 0;
712}
713
714static void __exit mei_wdt_exit(void)
715{
716 mei_cldev_driver_unregister(&mei_wdt_driver);
717}
718
719module_init(mei_wdt_init);
720module_exit(mei_wdt_exit);
721
722MODULE_AUTHOR("Intel Corporation");
723MODULE_LICENSE("GPL");
724MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog");