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 */ 57 enum 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 66 static 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 */ 100 struct 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 */ 124 struct 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 */ 138 struct 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 */ 151 struct 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 */ 162 struct 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 */ 174 static 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 */ 202 static 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 */ 228 static 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 */ 244 static 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 */ 270 static 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 */ 300 static 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 } 312 313 static 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 */ 322 static 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 */ 337 static 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 */ 347 static 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 */ 367 static 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; 401 402 out: 403 mutex_unlock(&wdt->reg_lock); 404 return ret; 405 } 406 407 static 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 */ 419 static 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); 480 481 out: 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 */ 491 static 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) 502 503 static 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 } 518 519 static const struct file_operations dbgfs_fops_activation = { 520 .open = simple_open, 521 .read = mei_dbgfs_read_activation, 522 .llseek = generic_file_llseek, 523 }; 524 525 static 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 } 538 539 static const struct file_operations dbgfs_fops_state = { 540 .open = simple_open, 541 .read = mei_dbgfs_read_state, 542 .llseek = generic_file_llseek, 543 }; 544 545 static void dbgfs_unregister(struct mei_wdt *wdt) 546 { 547 debugfs_remove_recursive(wdt->dbgfs_dir); 548 wdt->dbgfs_dir = NULL; 549 } 550 551 static 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; 570 err: 571 dbgfs_unregister(wdt); 572 return -ENODEV; 573 } 574 575 #else 576 577 static inline void dbgfs_unregister(struct mei_wdt *wdt) {} 578 579 static inline int dbgfs_register(struct mei_wdt *wdt) 580 { 581 return 0; 582 } 583 #endif /* CONFIG_DEBUG_FS */ 584 585 static 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; 639 640 err_disable: 641 mei_cldev_disable(cldev); 642 643 err_out: 644 kfree(wdt); 645 646 return ret; 647 } 648 649 static 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) 672 673 static struct mei_cl_device_id mei_wdt_tbl[] = { 674 { .uuid = MEI_UUID_WD, .version = MEI_CL_VERSION_ANY }, 675 /* required last entry */ 676 { } 677 }; 678 MODULE_DEVICE_TABLE(mei, mei_wdt_tbl); 679 680 static 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 }; 687 688 module_mei_cl_driver(mei_wdt_driver); 689 690 MODULE_AUTHOR("Intel Corporation"); 691 MODULE_LICENSE("GPL"); 692 MODULE_DESCRIPTION("Device driver for Intel MEI iAMT watchdog"); 693