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 */
49 enum 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
mei_wdt_state_str(enum mei_wdt_state state)58 static 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 */
92 struct 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 */
116 struct 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 */
130 struct 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 */
143 struct 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 */
154 struct 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 */
mei_wdt_ping(struct mei_wdt * wdt)166 static 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 */
mei_wdt_stop(struct mei_wdt * wdt)194 static 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 */
mei_wdt_ops_start(struct watchdog_device * wdd)220 static 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 */
mei_wdt_ops_stop(struct watchdog_device * wdd)236 static 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 */
mei_wdt_ops_ping(struct watchdog_device * wdd)262 static 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 */
mei_wdt_ops_set_timeout(struct watchdog_device * wdd,unsigned int timeout)292 static 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
305 static 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 */
314 static 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 */
__mei_wdt_is_registered(struct mei_wdt * wdt)329 static 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 */
mei_wdt_unregister(struct mei_wdt * wdt)339 static 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 */
mei_wdt_register(struct mei_wdt * wdt)359 static 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
386 ret = watchdog_register_device(&wdt->wdd);
387 if (ret)
388 watchdog_set_drvdata(&wdt->wdd, NULL);
389
390 wdt->state = MEI_WDT_IDLE;
391
392 out:
393 mutex_unlock(&wdt->reg_lock);
394 return ret;
395 }
396
mei_wdt_unregister_work(struct work_struct * work)397 static void mei_wdt_unregister_work(struct work_struct *work)
398 {
399 struct mei_wdt *wdt = container_of(work, struct mei_wdt, unregister);
400
401 mei_wdt_unregister(wdt);
402 }
403
404 /**
405 * mei_wdt_rx - callback for data receive
406 *
407 * @cldev: bus device
408 */
mei_wdt_rx(struct mei_cl_device * cldev)409 static void mei_wdt_rx(struct mei_cl_device *cldev)
410 {
411 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
412 struct mei_wdt_start_response res;
413 const size_t res_len = sizeof(res);
414 int ret;
415
416 ret = mei_cldev_recv(wdt->cldev, (u8 *)&res, res_len);
417 if (ret < 0) {
418 dev_err(&cldev->dev, "failure in recv %d\n", ret);
419 return;
420 }
421
422 /* Empty response can be sent on stop */
423 if (ret == 0)
424 return;
425
426 if (ret < sizeof(struct mei_mc_hdr)) {
427 dev_err(&cldev->dev, "recv small data %d\n", ret);
428 return;
429 }
430
431 if (res.hdr.command != MEI_MANAGEMENT_CONTROL ||
432 res.hdr.versionnumber != MEI_MC_VERSION_NUMBER) {
433 dev_err(&cldev->dev, "wrong command received\n");
434 return;
435 }
436
437 if (res.hdr.subcommand != MEI_MC_START_WD_TIMER_RES) {
438 dev_warn(&cldev->dev, "unsupported command %d :%s[%d]\n",
439 res.hdr.subcommand,
440 mei_wdt_state_str(wdt->state),
441 wdt->state);
442 return;
443 }
444
445 /* Run the unregistration in a worker as this can be
446 * run only after ping completion, otherwise the flow will
447 * deadlock on watchdog core mutex.
448 */
449 if (wdt->state == MEI_WDT_RUNNING) {
450 if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
451 wdt->state = MEI_WDT_NOT_REQUIRED;
452 schedule_work(&wdt->unregister);
453 }
454 goto out;
455 }
456
457 if (wdt->state == MEI_WDT_PROBE) {
458 if (res.wdstate & MEI_WDT_WDSTATE_NOT_REQUIRED) {
459 wdt->state = MEI_WDT_NOT_REQUIRED;
460 } else {
461 /* stop the watchdog and register watchdog device */
462 mei_wdt_stop(wdt);
463 mei_wdt_register(wdt);
464 }
465 return;
466 }
467
468 dev_warn(&cldev->dev, "not in correct state %s[%d]\n",
469 mei_wdt_state_str(wdt->state), wdt->state);
470
471 out:
472 if (!completion_done(&wdt->response))
473 complete(&wdt->response);
474 }
475
476 /*
477 * mei_wdt_notif - callback for event notification
478 *
479 * @cldev: bus device
480 */
mei_wdt_notif(struct mei_cl_device * cldev)481 static void mei_wdt_notif(struct mei_cl_device *cldev)
482 {
483 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
484
485 if (wdt->state != MEI_WDT_NOT_REQUIRED)
486 return;
487
488 mei_wdt_register(wdt);
489 }
490
491 #if IS_ENABLED(CONFIG_DEBUG_FS)
492
mei_dbgfs_read_activation(struct file * file,char __user * ubuf,size_t cnt,loff_t * ppos)493 static ssize_t mei_dbgfs_read_activation(struct file *file, char __user *ubuf,
494 size_t cnt, loff_t *ppos)
495 {
496 struct mei_wdt *wdt = file->private_data;
497 const size_t bufsz = 32;
498 char buf[32];
499 ssize_t pos;
500
501 mutex_lock(&wdt->reg_lock);
502 pos = scnprintf(buf, bufsz, "%s\n",
503 __mei_wdt_is_registered(wdt) ? "activated" : "deactivated");
504 mutex_unlock(&wdt->reg_lock);
505
506 return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
507 }
508
509 static const struct file_operations dbgfs_fops_activation = {
510 .open = simple_open,
511 .read = mei_dbgfs_read_activation,
512 .llseek = generic_file_llseek,
513 };
514
mei_dbgfs_read_state(struct file * file,char __user * ubuf,size_t cnt,loff_t * ppos)515 static ssize_t mei_dbgfs_read_state(struct file *file, char __user *ubuf,
516 size_t cnt, loff_t *ppos)
517 {
518 struct mei_wdt *wdt = file->private_data;
519 char buf[32];
520 ssize_t pos;
521
522 pos = scnprintf(buf, sizeof(buf), "state: %s\n",
523 mei_wdt_state_str(wdt->state));
524
525 return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
526 }
527
528 static const struct file_operations dbgfs_fops_state = {
529 .open = simple_open,
530 .read = mei_dbgfs_read_state,
531 .llseek = generic_file_llseek,
532 };
533
dbgfs_unregister(struct mei_wdt * wdt)534 static void dbgfs_unregister(struct mei_wdt *wdt)
535 {
536 debugfs_remove_recursive(wdt->dbgfs_dir);
537 wdt->dbgfs_dir = NULL;
538 }
539
dbgfs_register(struct mei_wdt * wdt)540 static void dbgfs_register(struct mei_wdt *wdt)
541 {
542 struct dentry *dir;
543
544 dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
545 wdt->dbgfs_dir = dir;
546
547 debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
548
549 debugfs_create_file("activation", S_IRUSR, dir, wdt,
550 &dbgfs_fops_activation);
551 }
552
553 #else
554
dbgfs_unregister(struct mei_wdt * wdt)555 static inline void dbgfs_unregister(struct mei_wdt *wdt) {}
dbgfs_register(struct mei_wdt * wdt)556 static inline void dbgfs_register(struct mei_wdt *wdt) {}
557 #endif /* CONFIG_DEBUG_FS */
558
mei_wdt_probe(struct mei_cl_device * cldev,const struct mei_cl_device_id * id)559 static int mei_wdt_probe(struct mei_cl_device *cldev,
560 const struct mei_cl_device_id *id)
561 {
562 struct mei_wdt *wdt;
563 int ret;
564
565 wdt = kzalloc(sizeof(struct mei_wdt), GFP_KERNEL);
566 if (!wdt)
567 return -ENOMEM;
568
569 wdt->timeout = MEI_WDT_DEFAULT_TIMEOUT;
570 wdt->state = MEI_WDT_PROBE;
571 wdt->cldev = cldev;
572 wdt->resp_required = mei_cldev_ver(cldev) > 0x1;
573 mutex_init(&wdt->reg_lock);
574 init_completion(&wdt->response);
575 INIT_WORK(&wdt->unregister, mei_wdt_unregister_work);
576
577 mei_cldev_set_drvdata(cldev, wdt);
578
579 ret = mei_cldev_enable(cldev);
580 if (ret < 0) {
581 dev_err(&cldev->dev, "Could not enable cl device\n");
582 goto err_out;
583 }
584
585 ret = mei_cldev_register_rx_cb(wdt->cldev, mei_wdt_rx);
586 if (ret) {
587 dev_err(&cldev->dev, "Could not reg rx event ret=%d\n", ret);
588 goto err_disable;
589 }
590
591 ret = mei_cldev_register_notif_cb(wdt->cldev, mei_wdt_notif);
592 /* on legacy devices notification is not supported
593 */
594 if (ret && ret != -EOPNOTSUPP) {
595 dev_err(&cldev->dev, "Could not reg notif event ret=%d\n", ret);
596 goto err_disable;
597 }
598
599 wd_info.firmware_version = mei_cldev_ver(cldev);
600
601 if (wdt->resp_required)
602 ret = mei_wdt_ping(wdt);
603 else
604 ret = mei_wdt_register(wdt);
605
606 if (ret)
607 goto err_disable;
608
609 dbgfs_register(wdt);
610
611 return 0;
612
613 err_disable:
614 mei_cldev_disable(cldev);
615
616 err_out:
617 kfree(wdt);
618
619 return ret;
620 }
621
mei_wdt_remove(struct mei_cl_device * cldev)622 static int mei_wdt_remove(struct mei_cl_device *cldev)
623 {
624 struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
625
626 /* Free the caller in case of fw initiated or unexpected reset */
627 if (!completion_done(&wdt->response))
628 complete(&wdt->response);
629
630 cancel_work_sync(&wdt->unregister);
631
632 mei_wdt_unregister(wdt);
633
634 mei_cldev_disable(cldev);
635
636 dbgfs_unregister(wdt);
637
638 kfree(wdt);
639
640 return 0;
641 }
642
643 #define MEI_UUID_WD UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, \
644 0x89, 0x9D, 0xA9, 0x15, 0x14, 0xCB, 0x32, 0xAB)
645
646 static const struct mei_cl_device_id mei_wdt_tbl[] = {
647 { .uuid = MEI_UUID_WD, .version = MEI_CL_VERSION_ANY },
648 /* required last entry */
649 { }
650 };
651 MODULE_DEVICE_TABLE(mei, mei_wdt_tbl);
652
653 static struct mei_cl_driver mei_wdt_driver = {
654 .id_table = mei_wdt_tbl,
655 .name = KBUILD_MODNAME,
656
657 .probe = mei_wdt_probe,
658 .remove = mei_wdt_remove,
659 };
660
661 module_mei_cl_driver(mei_wdt_driver);
662
663 MODULE_AUTHOR("Intel Corporation");
664 MODULE_LICENSE("GPL v2");
665 MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog");
666