drivers/char/ipmi/ipmi_ipmb.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /*
   4  * Driver to talk to a remote management controller on IPMB.
   5  */
   6
   7 #include <linux/acpi.h>
   8 #include <linux/errno.h>
   9 #include <linux/i2c.h>
  10 #include <linux/miscdevice.h>
  11 #include <linux/module.h>
  12 #include <linux/mutex.h>
  13 #include <linux/poll.h>
  14 #include <linux/slab.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/semaphore.h>
  17 #include <linux/kthread.h>
  18 #include <linux/wait.h>
  19 #include <linux/ipmi_msgdefs.h>
  20 #include <linux/ipmi_smi.h>
  21
  22 #define DEVICE_NAME "ipmi-ipmb"
  23
  24 static int bmcaddr = 0x20;
  25 module_param(bmcaddr, int, 0644);
  26 MODULE_PARM_DESC(bmcaddr, "Address to use for BMC.");
  27
  28 static unsigned int retry_time_ms = 250;
  29 module_param(retry_time_ms, uint, 0644);
  30 MODULE_PARM_DESC(retry_time_ms, "Timeout time between retries, in milliseconds.");
  31
  32 static unsigned int max_retries = 1;
  33 module_param(max_retries, uint, 0644);
  34 MODULE_PARM_DESC(max_retries, "Max resends of a command before timing out.");
  35
  36 /* Add room for the two slave addresses, two checksums, and rqSeq. */
  37 #define IPMB_MAX_MSG_LEN (IPMI_MAX_MSG_LENGTH + 5)
  38
  39 struct ipmi_ipmb_dev {
  40         struct ipmi_smi *intf;
  41         struct i2c_client *client;
  42         struct i2c_client *slave;
  43
  44         struct ipmi_smi_handlers handlers;
  45
  46         bool ready;
  47
  48         u8 curr_seq;
  49
  50         u8 bmcaddr;
  51         u32 retry_time_ms;
  52         u32 max_retries;
  53
  54         struct ipmi_smi_msg *next_msg;
  55         struct ipmi_smi_msg *working_msg;
  56
  57         /* Transmit thread. */
  58         struct task_struct *thread;
  59         struct semaphore wake_thread;
  60         struct semaphore got_rsp;
  61         spinlock_t lock;
  62         bool stopping;
  63
  64         u8 xmitmsg[IPMB_MAX_MSG_LEN];
  65         unsigned int xmitlen;
  66
  67         u8 rcvmsg[IPMB_MAX_MSG_LEN];
  68         unsigned int rcvlen;
  69         bool overrun;
  70 };
  71
  72 static bool valid_ipmb(struct ipmi_ipmb_dev *iidev)
  73 {
  74         u8 *msg = iidev->rcvmsg;
  75         u8 netfn;
  76
  77         if (iidev->overrun)
  78                 return false;
  79
  80         /* Minimum message size. */
  81         if (iidev->rcvlen < 7)
  82                 return false;
  83
  84         /* Is it a response? */
  85         netfn = msg[1] >> 2;
  86         if (netfn & 1) {
  87                 /* Response messages have an added completion code. */
  88                 if (iidev->rcvlen < 8)
  89                         return false;
  90         }
  91
  92         if (ipmb_checksum(msg, 3) != 0)
  93                 return false;
  94         if (ipmb_checksum(msg + 3, iidev->rcvlen - 3) != 0)
  95                 return false;
  96
  97         return true;
  98 }
  99
 100 static void ipmi_ipmb_check_msg_done(struct ipmi_ipmb_dev *iidev)
 101 {
 102         struct ipmi_smi_msg *imsg = NULL;
 103         u8 *msg = iidev->rcvmsg;
 104         bool is_cmd;
 105         unsigned long flags;
 106
 107         if (iidev->rcvlen == 0)
 108                 return;
 109         if (!valid_ipmb(iidev))
 110                 goto done;
 111
 112         is_cmd = ((msg[1] >> 2) & 1) == 0;
 113
 114         if (is_cmd) {
 115                 /* Ignore commands until we are up. */
 116                 if (!iidev->ready)
 117                         goto done;
 118
 119                 /* It's a command, allocate a message for it. */
 120                 imsg = ipmi_alloc_smi_msg();
 121                 if (!imsg)
 122                         goto done;
 123                 imsg->type = IPMI_SMI_MSG_TYPE_IPMB_DIRECT;
 124                 imsg->data_size = 0;
 125         } else {
 126                 spin_lock_irqsave(&iidev->lock, flags);
 127                 if (iidev->working_msg) {
 128                         u8 seq = msg[4] >> 2;
 129                         bool xmit_rsp = (iidev->working_msg->data[0] >> 2) & 1;
 130
 131                         /*
 132                          * Responses should carry the sequence we sent
 133                          * them with.  If it's a transmitted response,
 134                          * ignore it.  And if the message hasn't been
 135                          * transmitted, ignore it.
 136                          */
 137                         if (!xmit_rsp && seq == iidev->curr_seq) {
 138                                 iidev->curr_seq = (iidev->curr_seq + 1) & 0x3f;
 139
 140                                 imsg = iidev->working_msg;
 141                                 iidev->working_msg = NULL;
 142                         }
 143                 }
 144                 spin_unlock_irqrestore(&iidev->lock, flags);
 145         }
 146
 147         if (!imsg)
 148                 goto done;
 149
 150         if (imsg->type == IPMI_SMI_MSG_TYPE_IPMB_DIRECT) {
 151                 imsg->rsp[0] = msg[1]; /* NetFn/LUN */
 152                 /*
 153                  * Keep the source address, rqSeq.  Drop the trailing
 154                  * checksum.
 155                  */
 156                 memcpy(imsg->rsp + 1, msg + 3, iidev->rcvlen - 4);
 157                 imsg->rsp_size = iidev->rcvlen - 3;
 158         } else {
 159                 imsg->rsp[0] = msg[1]; /* NetFn/LUN */
 160                 /*
 161                  * Skip the source address, rqSeq.  Drop the trailing
 162                  * checksum.
 163                  */
 164                 memcpy(imsg->rsp + 1, msg + 5, iidev->rcvlen - 6);
 165                 imsg->rsp_size = iidev->rcvlen - 5;
 166         }
 167         ipmi_smi_msg_received(iidev->intf, imsg);
 168         if (!is_cmd)
 169                 up(&iidev->got_rsp);
 170
 171 done:
 172         iidev->overrun = false;
 173         iidev->rcvlen = 0;
 174 }
 175
 176 /*
 177  * The IPMB protocol only supports i2c writes so there is no need to
 178  * support I2C_SLAVE_READ* events, except to know if the other end has
 179  * issued a read without going to stop mode.
 180  */
 181 static int ipmi_ipmb_slave_cb(struct i2c_client *client,
 182                               enum i2c_slave_event event, u8 *val)
 183 {
 184         struct ipmi_ipmb_dev *iidev = i2c_get_clientdata(client);
 185
 186         switch (event) {
 187         case I2C_SLAVE_WRITE_REQUESTED:
 188                 ipmi_ipmb_check_msg_done(iidev);
 189                 /*
 190                  * First byte is the slave address, to ease the checksum
 191                  * calculation.
 192                  */
 193                 iidev->rcvmsg[0] = client->addr << 1;
 194                 iidev->rcvlen = 1;
 195                 break;
 196
 197         case I2C_SLAVE_WRITE_RECEIVED:
 198                 if (iidev->rcvlen >= sizeof(iidev->rcvmsg))
 199                         iidev->overrun = true;
 200                 else
 201                         iidev->rcvmsg[iidev->rcvlen++] = *val;
 202                 break;
 203
 204         case I2C_SLAVE_READ_REQUESTED:
 205         case I2C_SLAVE_STOP:
 206                 ipmi_ipmb_check_msg_done(iidev);
 207                 break;
 208
 209         case I2C_SLAVE_READ_PROCESSED:
 210                 break;
 211         }
 212
 213         return 0;
 214 }
 215
 216 static void ipmi_ipmb_send_response(struct ipmi_ipmb_dev *iidev,
 217                                     struct ipmi_smi_msg *msg, u8 cc)
 218 {
 219         if ((msg->data[0] >> 2) & 1) {
 220                 /*
 221                  * It's a response being sent, we need to return a
 222                  * response to the response.  Fake a send msg command
 223                  * response with channel 0.  This will always be ipmb
 224                  * direct.
 225                  */
 226                 msg->data[0] = (IPMI_NETFN_APP_REQUEST | 1) << 2;
 227                 msg->data[3] = IPMI_SEND_MSG_CMD;
 228                 msg->data[4] = cc;
 229                 msg->data_size = 5;
 230         }
 231         msg->rsp[0] = msg->data[0] | (1 << 2);
 232         if (msg->type == IPMI_SMI_MSG_TYPE_IPMB_DIRECT) {
 233                 msg->rsp[1] = msg->data[1];
 234                 msg->rsp[2] = msg->data[2];
 235                 msg->rsp[3] = msg->data[3];
 236                 msg->rsp[4] = cc;
 237                 msg->rsp_size = 5;
 238         } else {
 239                 msg->rsp[1] = msg->data[1];
 240                 msg->rsp[2] = cc;
 241                 msg->rsp_size = 3;
 242         }
 243         ipmi_smi_msg_received(iidev->intf, msg);
 244 }
 245
 246 static void ipmi_ipmb_format_for_xmit(struct ipmi_ipmb_dev *iidev,
 247                                       struct ipmi_smi_msg *msg)
 248 {
 249         if (msg->type == IPMI_SMI_MSG_TYPE_IPMB_DIRECT) {
 250                 iidev->xmitmsg[0] = msg->data[1];
 251                 iidev->xmitmsg[1] = msg->data[0];
 252                 memcpy(iidev->xmitmsg + 4, msg->data + 2, msg->data_size - 2);
 253                 iidev->xmitlen = msg->data_size + 2;
 254         } else {
 255                 iidev->xmitmsg[0] = iidev->bmcaddr;
 256                 iidev->xmitmsg[1] = msg->data[0];
 257                 iidev->xmitmsg[4] = 0;
 258                 memcpy(iidev->xmitmsg + 5, msg->data + 1, msg->data_size - 1);
 259                 iidev->xmitlen = msg->data_size + 4;
 260         }
 261         iidev->xmitmsg[3] = iidev->slave->addr << 1;
 262         if (((msg->data[0] >> 2) & 1) == 0)
 263                 /* If it's a command, put in our own sequence number. */
 264                 iidev->xmitmsg[4] = ((iidev->xmitmsg[4] & 0x03) |
 265                                      (iidev->curr_seq << 2));
 266
 267         /* Now add on the final checksums. */
 268         iidev->xmitmsg[2] = ipmb_checksum(iidev->xmitmsg, 2);
 269         iidev->xmitmsg[iidev->xmitlen] =
 270                 ipmb_checksum(iidev->xmitmsg + 3, iidev->xmitlen - 3);
 271         iidev->xmitlen++;
 272 }
 273
 274 static int ipmi_ipmb_thread(void *data)
 275 {
 276         struct ipmi_ipmb_dev *iidev = data;
 277
 278         while (!kthread_should_stop()) {
 279                 long ret;
 280                 struct i2c_msg i2c_msg;
 281                 struct ipmi_smi_msg *msg = NULL;
 282                 unsigned long flags;
 283                 unsigned int retries = 0;
 284
 285                 /* Wait for a message to send */
 286                 ret = down_interruptible(&iidev->wake_thread);
 287                 if (iidev->stopping)
 288                         break;
 289                 if (ret)
 290                         continue;
 291
 292                 spin_lock_irqsave(&iidev->lock, flags);
 293                 if (iidev->next_msg) {
 294                         msg = iidev->next_msg;
 295                         iidev->next_msg = NULL;
 296                 }
 297                 spin_unlock_irqrestore(&iidev->lock, flags);
 298                 if (!msg)
 299                         continue;
 300
 301                 ipmi_ipmb_format_for_xmit(iidev, msg);
 302
 303 retry:
 304                 i2c_msg.len = iidev->xmitlen - 1;
 305                 if (i2c_msg.len > 32) {
 306                         ipmi_ipmb_send_response(iidev, msg,
 307                                                 IPMI_REQ_LEN_EXCEEDED_ERR);
 308                         continue;
 309                 }
 310
 311                 i2c_msg.addr = iidev->xmitmsg[0] >> 1;
 312                 i2c_msg.flags = 0;
 313                 i2c_msg.buf = iidev->xmitmsg + 1;
 314
 315                 /* Rely on i2c_transfer for a barrier. */
 316                 iidev->working_msg = msg;
 317
 318                 ret = i2c_transfer(iidev->client->adapter, &i2c_msg, 1);
 319
 320                 if ((msg->data[0] >> 2) & 1) {
 321                         /*
 322                          * It's a response, nothing will be returned
 323                          * by the other end.
 324                          */
 325
 326                         iidev->working_msg = NULL;
 327                         ipmi_ipmb_send_response(iidev, msg,
 328                                                 ret < 0 ? IPMI_BUS_ERR : 0);
 329                         continue;
 330                 }
 331                 if (ret < 0) {
 332                         iidev->working_msg = NULL;
 333                         ipmi_ipmb_send_response(iidev, msg, IPMI_BUS_ERR);
 334                         continue;
 335                 }
 336
 337                 /* A command was sent, wait for its response. */
 338                 ret = down_timeout(&iidev->got_rsp,
 339                                    msecs_to_jiffies(iidev->retry_time_ms));
 340
 341                 /*
 342                  * Grab the message if we can.  If the handler hasn't
 343                  * already handled it, the message will still be there.
 344                  */
 345                 spin_lock_irqsave(&iidev->lock, flags);
 346                 msg = iidev->working_msg;
 347                 iidev->working_msg = NULL;
 348                 spin_unlock_irqrestore(&iidev->lock, flags);
 349
 350                 if (!msg && ret) {
 351                         /*
 352                          * If working_msg is not set and we timed out,
 353                          * that means the message grabbed by
 354                          * check_msg_done before we could grab it
 355                          * here.  Wait again for check_msg_done to up
 356                          * the semaphore.
 357                          */
 358                         down(&iidev->got_rsp);
 359                 } else if (msg && ++retries <= iidev->max_retries) {
 360                         spin_lock_irqsave(&iidev->lock, flags);
 361                         iidev->working_msg = msg;
 362                         spin_unlock_irqrestore(&iidev->lock, flags);
 363                         goto retry;
 364                 }
 365
 366                 if (msg)
 367                         ipmi_ipmb_send_response(iidev, msg, IPMI_TIMEOUT_ERR);
 368         }
 369
 370         if (iidev->next_msg)
 371                 /* Return an unspecified error. */
 372                 ipmi_ipmb_send_response(iidev, iidev->next_msg, 0xff);
 373
 374         return 0;
 375 }
 376
 377 static int ipmi_ipmb_start_processing(void *send_info,
 378                                       struct ipmi_smi *new_intf)
 379 {
 380         struct ipmi_ipmb_dev *iidev = send_info;
 381
 382         iidev->intf = new_intf;
 383         iidev->ready = true;
 384         return 0;
 385 }
 386
 387 static void ipmi_ipmb_stop_thread(struct ipmi_ipmb_dev *iidev)
 388 {
 389         if (iidev->thread) {
 390                 struct task_struct *t = iidev->thread;
 391
 392                 iidev->thread = NULL;
 393                 iidev->stopping = true;
 394                 up(&iidev->wake_thread);
 395                 up(&iidev->got_rsp);
 396                 kthread_stop(t);
 397         }
 398 }
 399
 400 static void ipmi_ipmb_shutdown(void *send_info)
 401 {
 402         struct ipmi_ipmb_dev *iidev = send_info;
 403
 404         ipmi_ipmb_stop_thread(iidev);
 405 }
 406
 407 static void ipmi_ipmb_sender(void *send_info,
 408                              struct ipmi_smi_msg *msg)
 409 {
 410         struct ipmi_ipmb_dev *iidev = send_info;
 411         unsigned long flags;
 412
 413         spin_lock_irqsave(&iidev->lock, flags);
 414         BUG_ON(iidev->next_msg);
 415
 416         iidev->next_msg = msg;
 417         spin_unlock_irqrestore(&iidev->lock, flags);
 418
 419         up(&iidev->wake_thread);
 420 }
 421
 422 static void ipmi_ipmb_request_events(void *send_info)
 423 {
 424         /* We don't fetch events here. */
 425 }
 426
 427 static void ipmi_ipmb_cleanup(struct ipmi_ipmb_dev *iidev)
 428 {
 429         if (iidev->slave) {
 430                 i2c_slave_unregister(iidev->slave);
 431                 if (iidev->slave != iidev->client)
 432                         i2c_unregister_device(iidev->slave);
 433         }
 434         iidev->slave = NULL;
 435         iidev->client = NULL;
 436         ipmi_ipmb_stop_thread(iidev);
 437 }
 438
 439 static void ipmi_ipmb_remove(struct i2c_client *client)
 440 {
 441         struct ipmi_ipmb_dev *iidev = i2c_get_clientdata(client);
 442
 443         ipmi_ipmb_cleanup(iidev);
 444         ipmi_unregister_smi(iidev->intf);
 445 }
 446
 447 static int ipmi_ipmb_probe(struct i2c_client *client)
 448 {
 449         struct device *dev = &client->dev;
 450         struct ipmi_ipmb_dev *iidev;
 451         struct device_node *slave_np;
 452         struct i2c_adapter *slave_adap = NULL;
 453         struct i2c_client *slave = NULL;
 454         int rv;
 455
 456         iidev = devm_kzalloc(&client->dev, sizeof(*iidev), GFP_KERNEL);
 457         if (!iidev)
 458                 return -ENOMEM;
 459
 460         if (of_property_read_u8(dev->of_node, "bmcaddr", &iidev->bmcaddr) != 0)
 461                 iidev->bmcaddr = bmcaddr;
 462         if (iidev->bmcaddr == 0 || iidev->bmcaddr & 1) {
 463                 /* Can't have the write bit set. */
 464                 dev_notice(&client->dev,
 465                            "Invalid bmc address value %2.2x\n", iidev->bmcaddr);
 466                 return -EINVAL;
 467         }
 468
 469         if (of_property_read_u32(dev->of_node, "retry-time",
 470                                  &iidev->retry_time_ms) != 0)
 471                 iidev->retry_time_ms = retry_time_ms;
 472
 473         if (of_property_read_u32(dev->of_node, "max-retries",
 474                                  &iidev->max_retries) != 0)
 475                 iidev->max_retries = max_retries;
 476
 477         slave_np = of_parse_phandle(dev->of_node, "slave-dev", 0);
 478         if (slave_np) {
 479                 slave_adap = of_get_i2c_adapter_by_node(slave_np);
 480                 of_node_put(slave_np);
 481                 if (!slave_adap) {
 482                         dev_notice(&client->dev,
 483                                    "Could not find slave adapter\n");
 484                         return -EINVAL;
 485                 }
 486         }
 487
 488         iidev->client = client;
 489
 490         if (slave_adap) {
 491                 struct i2c_board_info binfo;
 492
 493                 memset(&binfo, 0, sizeof(binfo));
 494                 strscpy(binfo.type, "ipmb-slave", I2C_NAME_SIZE);
 495                 binfo.addr = client->addr;
 496                 binfo.flags = I2C_CLIENT_SLAVE;
 497                 slave = i2c_new_client_device(slave_adap, &binfo);
 498                 i2c_put_adapter(slave_adap);
 499                 if (IS_ERR(slave)) {
 500                         rv = PTR_ERR(slave);
 501                         dev_notice(&client->dev,
 502                                    "Could not allocate slave device: %d\n", rv);
 503                         return rv;
 504                 }
 505                 i2c_set_clientdata(slave, iidev);
 506         } else {
 507                 slave = client;
 508         }
 509         i2c_set_clientdata(client, iidev);
 510         slave->flags |= I2C_CLIENT_SLAVE;
 511
 512         rv = i2c_slave_register(slave, ipmi_ipmb_slave_cb);
 513         if (rv)
 514                 goto out_err;
 515         iidev->slave = slave;
 516         slave = NULL;
 517
 518         iidev->handlers.flags = IPMI_SMI_CAN_HANDLE_IPMB_DIRECT;
 519         iidev->handlers.start_processing = ipmi_ipmb_start_processing;
 520         iidev->handlers.shutdown = ipmi_ipmb_shutdown;
 521         iidev->handlers.sender = ipmi_ipmb_sender;
 522         iidev->handlers.request_events = ipmi_ipmb_request_events;
 523
 524         spin_lock_init(&iidev->lock);
 525         sema_init(&iidev->wake_thread, 0);
 526         sema_init(&iidev->got_rsp, 0);
 527
 528         iidev->thread = kthread_run(ipmi_ipmb_thread, iidev,
 529                                     "kipmb%4.4x", client->addr);
 530         if (IS_ERR(iidev->thread)) {
 531                 rv = PTR_ERR(iidev->thread);
 532                 dev_notice(&client->dev,
 533                            "Could not start kernel thread: error %d\n", rv);
 534                 goto out_err;
 535         }
 536
 537         rv = ipmi_register_smi(&iidev->handlers,
 538                                iidev,
 539                                &client->dev,
 540                                iidev->bmcaddr);
 541         if (rv)
 542                 goto out_err;
 543
 544         return 0;
 545
 546 out_err:
 547         if (slave && slave != client)
 548                 i2c_unregister_device(slave);
 549         ipmi_ipmb_cleanup(iidev);
 550         return rv;
 551 }
 552
 553 #ifdef CONFIG_OF
 554 static const struct of_device_id of_ipmi_ipmb_match[] = {
 555         { .type = "ipmi", .compatible = DEVICE_NAME },
 556         {},
 557 };
 558 MODULE_DEVICE_TABLE(of, of_ipmi_ipmb_match);
 559 #else
 560 #define of_ipmi_ipmb_match NULL
 561 #endif
 562
 563 static const struct i2c_device_id ipmi_ipmb_id[] = {
 564         { DEVICE_NAME, 0 },
 565         {},
 566 };
 567 MODULE_DEVICE_TABLE(i2c, ipmi_ipmb_id);
 568
 569 static struct i2c_driver ipmi_ipmb_driver = {
 570         .class          = I2C_CLASS_HWMON,
 571         .driver = {
 572                 .name = DEVICE_NAME,
 573                 .of_match_table = of_ipmi_ipmb_match,
 574         },
 575         .probe          = ipmi_ipmb_probe,
 576         .remove         = ipmi_ipmb_remove,
 577         .id_table       = ipmi_ipmb_id,
 578 };
 579 module_i2c_driver(ipmi_ipmb_driver);
 580
 581 MODULE_AUTHOR("Corey Minyard");
 582 MODULE_DESCRIPTION("IPMI IPMB driver");
 583 MODULE_LICENSE("GPL v2");