drivers/char/ipmi/ipmi_bt_sm.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *  ipmi_bt_sm.c
   4  *
   5  *  The state machine for an Open IPMI BT sub-driver under ipmi_si.c, part
   6  *  of the driver architecture at http://sourceforge.net/projects/openipmi
   7  *
   8  *  Author:     Rocky Craig <first.last@hp.com>
   9  */
  10
  11 #define DEBUG /* So dev_dbg() is always available. */
  12
  13 #include <linux/kernel.h> /* For printk. */
  14 #include <linux/string.h>
  15 #include <linux/module.h>
  16 #include <linux/moduleparam.h>
  17 #include <linux/ipmi_msgdefs.h>         /* for completion codes */
  18 #include "ipmi_si_sm.h"
  19
  20 #define BT_DEBUG_OFF    0       /* Used in production */
  21 #define BT_DEBUG_ENABLE 1       /* Generic messages */
  22 #define BT_DEBUG_MSG    2       /* Prints all request/response buffers */
  23 #define BT_DEBUG_STATES 4       /* Verbose look at state changes */
  24 /*
  25  * BT_DEBUG_OFF must be zero to correspond to the default uninitialized
  26  * value
  27  */
  28
  29 static int bt_debug; /* 0 == BT_DEBUG_OFF */
  30
  31 module_param(bt_debug, int, 0644);
  32 MODULE_PARM_DESC(bt_debug, "debug bitmask, 1=enable, 2=messages, 4=states");
  33
  34 /*
  35  * Typical "Get BT Capabilities" values are 2-3 retries, 5-10 seconds,
  36  * and 64 byte buffers.  However, one HP implementation wants 255 bytes of
  37  * buffer (with a documented message of 160 bytes) so go for the max.
  38  * Since the Open IPMI architecture is single-message oriented at this
  39  * stage, the queue depth of BT is of no concern.
  40  */
  41
  42 #define BT_NORMAL_TIMEOUT       5       /* seconds */
  43 #define BT_NORMAL_RETRY_LIMIT   2
  44 #define BT_RESET_DELAY          6       /* seconds after warm reset */
  45
  46 /*
  47  * States are written in chronological order and usually cover
  48  * multiple rows of the state table discussion in the IPMI spec.
  49  */
  50
  51 enum bt_states {
  52         BT_STATE_IDLE = 0,      /* Order is critical in this list */
  53         BT_STATE_XACTION_START,
  54         BT_STATE_WRITE_BYTES,
  55         BT_STATE_WRITE_CONSUME,
  56         BT_STATE_READ_WAIT,
  57         BT_STATE_CLEAR_B2H,
  58         BT_STATE_READ_BYTES,
  59         BT_STATE_RESET1,        /* These must come last */
  60         BT_STATE_RESET2,
  61         BT_STATE_RESET3,
  62         BT_STATE_RESTART,
  63         BT_STATE_PRINTME,
  64         BT_STATE_LONG_BUSY      /* BT doesn't get hosed :-) */
  65 };
  66
  67 /*
  68  * Macros seen at the end of state "case" blocks.  They help with legibility
  69  * and debugging.
  70  */
  71
  72 #define BT_STATE_CHANGE(X, Y) { bt->state = X; return Y; }
  73
  74 #define BT_SI_SM_RETURN(Y)   { last_printed = BT_STATE_PRINTME; return Y; }
  75
  76 struct si_sm_data {
  77         enum bt_states  state;
  78         unsigned char   seq;            /* BT sequence number */
  79         struct si_sm_io *io;
  80         unsigned char   write_data[IPMI_MAX_MSG_LENGTH + 2]; /* +2 for memcpy */
  81         int             write_count;
  82         unsigned char   read_data[IPMI_MAX_MSG_LENGTH + 2]; /* +2 for memcpy */
  83         int             read_count;
  84         int             truncated;
  85         long            timeout;        /* microseconds countdown */
  86         int             error_retries;  /* end of "common" fields */
  87         int             nonzero_status; /* hung BMCs stay all 0 */
  88         enum bt_states  complete;       /* to divert the state machine */
  89         long            BT_CAP_req2rsp;
  90         int             BT_CAP_retries; /* Recommended retries */
  91 };
  92
  93 #define BT_CLR_WR_PTR   0x01    /* See IPMI 1.5 table 11.6.4 */
  94 #define BT_CLR_RD_PTR   0x02
  95 #define BT_H2B_ATN      0x04
  96 #define BT_B2H_ATN      0x08
  97 #define BT_SMS_ATN      0x10
  98 #define BT_OEM0         0x20
  99 #define BT_H_BUSY       0x40
 100 #define BT_B_BUSY       0x80
 101
 102 /*
 103  * Some bits are toggled on each write: write once to set it, once
 104  * more to clear it; writing a zero does nothing.  To absolutely
 105  * clear it, check its state and write if set.  This avoids the "get
 106  * current then use as mask" scheme to modify one bit.  Note that the
 107  * variable "bt" is hardcoded into these macros.
 108  */
 109
 110 #define BT_STATUS       bt->io->inputb(bt->io, 0)
 111 #define BT_CONTROL(x)   bt->io->outputb(bt->io, 0, x)
 112
 113 #define BMC2HOST        bt->io->inputb(bt->io, 1)
 114 #define HOST2BMC(x)     bt->io->outputb(bt->io, 1, x)
 115
 116 #define BT_INTMASK_R    bt->io->inputb(bt->io, 2)
 117 #define BT_INTMASK_W(x) bt->io->outputb(bt->io, 2, x)
 118
 119 /*
 120  * Convenience routines for debugging.  These are not multi-open safe!
 121  * Note the macros have hardcoded variables in them.
 122  */
 123
 124 static char *state2txt(unsigned char state)
 125 {
 126         switch (state) {
 127         case BT_STATE_IDLE:             return("IDLE");
 128         case BT_STATE_XACTION_START:    return("XACTION");
 129         case BT_STATE_WRITE_BYTES:      return("WR_BYTES");
 130         case BT_STATE_WRITE_CONSUME:    return("WR_CONSUME");
 131         case BT_STATE_READ_WAIT:        return("RD_WAIT");
 132         case BT_STATE_CLEAR_B2H:        return("CLEAR_B2H");
 133         case BT_STATE_READ_BYTES:       return("RD_BYTES");
 134         case BT_STATE_RESET1:           return("RESET1");
 135         case BT_STATE_RESET2:           return("RESET2");
 136         case BT_STATE_RESET3:           return("RESET3");
 137         case BT_STATE_RESTART:          return("RESTART");
 138         case BT_STATE_LONG_BUSY:        return("LONG_BUSY");
 139         }
 140         return("BAD STATE");
 141 }
 142 #define STATE2TXT state2txt(bt->state)
 143
 144 static char *status2txt(unsigned char status)
 145 {
 146         /*
 147          * This cannot be called by two threads at the same time and
 148          * the buffer is always consumed immediately, so the static is
 149          * safe to use.
 150          */
 151         static char buf[40];
 152
 153         strcpy(buf, "[ ");
 154         if (status & BT_B_BUSY)
 155                 strcat(buf, "B_BUSY ");
 156         if (status & BT_H_BUSY)
 157                 strcat(buf, "H_BUSY ");
 158         if (status & BT_OEM0)
 159                 strcat(buf, "OEM0 ");
 160         if (status & BT_SMS_ATN)
 161                 strcat(buf, "SMS ");
 162         if (status & BT_B2H_ATN)
 163                 strcat(buf, "B2H ");
 164         if (status & BT_H2B_ATN)
 165                 strcat(buf, "H2B ");
 166         strcat(buf, "]");
 167         return buf;
 168 }
 169 #define STATUS2TXT status2txt(status)
 170
 171 /* called externally at insmod time, and internally on cleanup */
 172
 173 static unsigned int bt_init_data(struct si_sm_data *bt, struct si_sm_io *io)
 174 {
 175         memset(bt, 0, sizeof(struct si_sm_data));
 176         if (bt->io != io) {
 177                 /* external: one-time only things */
 178                 bt->io = io;
 179                 bt->seq = 0;
 180         }
 181         bt->state = BT_STATE_IDLE;      /* start here */
 182         bt->complete = BT_STATE_IDLE;   /* end here */
 183         bt->BT_CAP_req2rsp = BT_NORMAL_TIMEOUT * USEC_PER_SEC;
 184         bt->BT_CAP_retries = BT_NORMAL_RETRY_LIMIT;
 185         return 3; /* We claim 3 bytes of space; ought to check SPMI table */
 186 }
 187
 188 /* Jam a completion code (probably an error) into a response */
 189
 190 static void force_result(struct si_sm_data *bt, unsigned char completion_code)
 191 {
 192         bt->read_data[0] = 4;                           /* # following bytes */
 193         bt->read_data[1] = bt->write_data[1] | 4;       /* Odd NetFn/LUN */
 194         bt->read_data[2] = bt->write_data[2];           /* seq (ignored) */
 195         bt->read_data[3] = bt->write_data[3];           /* Command */
 196         bt->read_data[4] = completion_code;
 197         bt->read_count = 5;
 198 }
 199
 200 /* The upper state machine starts here */
 201
 202 static int bt_start_transaction(struct si_sm_data *bt,
 203                                 unsigned char *data,
 204                                 unsigned int size)
 205 {
 206         unsigned int i;
 207
 208         if (size < 2)
 209                 return IPMI_REQ_LEN_INVALID_ERR;
 210         if (size > IPMI_MAX_MSG_LENGTH)
 211                 return IPMI_REQ_LEN_EXCEEDED_ERR;
 212
 213         if (bt->state == BT_STATE_LONG_BUSY)
 214                 return IPMI_NODE_BUSY_ERR;
 215
 216         if (bt->state != BT_STATE_IDLE)
 217                 return IPMI_NOT_IN_MY_STATE_ERR;
 218
 219         if (bt_debug & BT_DEBUG_MSG) {
 220                 dev_dbg(bt->io->dev, "+++++++++++++++++ New command\n");
 221                 dev_dbg(bt->io->dev, "NetFn/LUN CMD [%d data]:", size - 2);
 222                 for (i = 0; i < size; i ++)
 223                         pr_cont(" %02x", data[i]);
 224                 pr_cont("\n");
 225         }
 226         bt->write_data[0] = size + 1;   /* all data plus seq byte */
 227         bt->write_data[1] = *data;      /* NetFn/LUN */
 228         bt->write_data[2] = bt->seq++;
 229         memcpy(bt->write_data + 3, data + 1, size - 1);
 230         bt->write_count = size + 2;
 231         bt->error_retries = 0;
 232         bt->nonzero_status = 0;
 233         bt->truncated = 0;
 234         bt->state = BT_STATE_XACTION_START;
 235         bt->timeout = bt->BT_CAP_req2rsp;
 236         force_result(bt, IPMI_ERR_UNSPECIFIED);
 237         return 0;
 238 }
 239
 240 /*
 241  * After the upper state machine has been told SI_SM_TRANSACTION_COMPLETE
 242  * it calls this.  Strip out the length and seq bytes.
 243  */
 244
 245 static int bt_get_result(struct si_sm_data *bt,
 246                          unsigned char *data,
 247                          unsigned int length)
 248 {
 249         int i, msg_len;
 250
 251         msg_len = bt->read_count - 2;           /* account for length & seq */
 252         if (msg_len < 3 || msg_len > IPMI_MAX_MSG_LENGTH) {
 253                 force_result(bt, IPMI_ERR_UNSPECIFIED);
 254                 msg_len = 3;
 255         }
 256         data[0] = bt->read_data[1];
 257         data[1] = bt->read_data[3];
 258         if (length < msg_len || bt->truncated) {
 259                 data[2] = IPMI_ERR_MSG_TRUNCATED;
 260                 msg_len = 3;
 261         } else
 262                 memcpy(data + 2, bt->read_data + 4, msg_len - 2);
 263
 264         if (bt_debug & BT_DEBUG_MSG) {
 265                 dev_dbg(bt->io->dev, "result %d bytes:", msg_len);
 266                 for (i = 0; i < msg_len; i++)
 267                         pr_cont(" %02x", data[i]);
 268                 pr_cont("\n");
 269         }
 270         return msg_len;
 271 }
 272
 273 /* This bit's functionality is optional */
 274 #define BT_BMC_HWRST    0x80
 275
 276 static void reset_flags(struct si_sm_data *bt)
 277 {
 278         if (bt_debug)
 279                 dev_dbg(bt->io->dev, "flag reset %s\n", status2txt(BT_STATUS));
 280         if (BT_STATUS & BT_H_BUSY)
 281                 BT_CONTROL(BT_H_BUSY);  /* force clear */
 282         BT_CONTROL(BT_CLR_WR_PTR);      /* always reset */
 283         BT_CONTROL(BT_SMS_ATN);         /* always clear */
 284         BT_INTMASK_W(BT_BMC_HWRST);
 285 }
 286
 287 /*
 288  * Get rid of an unwanted/stale response.  This should only be needed for
 289  * BMCs that support multiple outstanding requests.
 290  */
 291
 292 static void drain_BMC2HOST(struct si_sm_data *bt)
 293 {
 294         int i, size;
 295
 296         if (!(BT_STATUS & BT_B2H_ATN))  /* Not signalling a response */
 297                 return;
 298
 299         BT_CONTROL(BT_H_BUSY);          /* now set */
 300         BT_CONTROL(BT_B2H_ATN);         /* always clear */
 301         BT_STATUS;                      /* pause */
 302         BT_CONTROL(BT_B2H_ATN);         /* some BMCs are stubborn */
 303         BT_CONTROL(BT_CLR_RD_PTR);      /* always reset */
 304         if (bt_debug)
 305                 dev_dbg(bt->io->dev, "stale response %s; ",
 306                         status2txt(BT_STATUS));
 307         size = BMC2HOST;
 308         for (i = 0; i < size ; i++)
 309                 BMC2HOST;
 310         BT_CONTROL(BT_H_BUSY);          /* now clear */
 311         if (bt_debug)
 312                 pr_cont("drained %d bytes\n", size + 1);
 313 }
 314
 315 static inline void write_all_bytes(struct si_sm_data *bt)
 316 {
 317         int i;
 318
 319         if (bt_debug & BT_DEBUG_MSG) {
 320                 dev_dbg(bt->io->dev, "write %d bytes seq=0x%02X",
 321                         bt->write_count, bt->seq);
 322                 for (i = 0; i < bt->write_count; i++)
 323                         pr_cont(" %02x", bt->write_data[i]);
 324                 pr_cont("\n");
 325         }
 326         for (i = 0; i < bt->write_count; i++)
 327                 HOST2BMC(bt->write_data[i]);
 328 }
 329
 330 static inline int read_all_bytes(struct si_sm_data *bt)
 331 {
 332         unsigned int i;
 333
 334         /*
 335          * length is "framing info", minimum = 4: NetFn, Seq, Cmd, cCode.
 336          * Keep layout of first four bytes aligned with write_data[]
 337          */
 338
 339         bt->read_data[0] = BMC2HOST;
 340         bt->read_count = bt->read_data[0];
 341
 342         if (bt->read_count < 4 || bt->read_count >= IPMI_MAX_MSG_LENGTH) {
 343                 if (bt_debug & BT_DEBUG_MSG)
 344                         dev_dbg(bt->io->dev,
 345                                 "bad raw rsp len=%d\n", bt->read_count);
 346                 bt->truncated = 1;
 347                 return 1;       /* let next XACTION START clean it up */
 348         }
 349         for (i = 1; i <= bt->read_count; i++)
 350                 bt->read_data[i] = BMC2HOST;
 351         bt->read_count++;       /* Account internally for length byte */
 352
 353         if (bt_debug & BT_DEBUG_MSG) {
 354                 int max = bt->read_count;
 355
 356                 dev_dbg(bt->io->dev,
 357                         "got %d bytes seq=0x%02X", max, bt->read_data[2]);
 358                 if (max > 16)
 359                         max = 16;
 360                 for (i = 0; i < max; i++)
 361                         pr_cont(" %02x", bt->read_data[i]);
 362                 pr_cont("%s\n", bt->read_count == max ? "" : " ...");
 363         }
 364
 365         /* per the spec, the (NetFn[1], Seq[2], Cmd[3]) tuples must match */
 366         if ((bt->read_data[3] == bt->write_data[3]) &&
 367             (bt->read_data[2] == bt->write_data[2]) &&
 368             ((bt->read_data[1] & 0xF8) == (bt->write_data[1] & 0xF8)))
 369                         return 1;
 370
 371         if (bt_debug & BT_DEBUG_MSG)
 372                 dev_dbg(bt->io->dev,
 373                         "IPMI BT: bad packet: want 0x(%02X, %02X, %02X) got (%02X, %02X, %02X)\n",
 374                         bt->write_data[1] | 0x04, bt->write_data[2],
 375                         bt->write_data[3],
 376                         bt->read_data[1],  bt->read_data[2],  bt->read_data[3]);
 377         return 0;
 378 }
 379
 380 /* Restart if retries are left, or return an error completion code */
 381
 382 static enum si_sm_result error_recovery(struct si_sm_data *bt,
 383                                         unsigned char status,
 384                                         unsigned char cCode)
 385 {
 386         char *reason;
 387
 388         bt->timeout = bt->BT_CAP_req2rsp;
 389
 390         switch (cCode) {
 391         case IPMI_TIMEOUT_ERR:
 392                 reason = "timeout";
 393                 break;
 394         default:
 395                 reason = "internal error";
 396                 break;
 397         }
 398
 399         dev_warn(bt->io->dev, "IPMI BT: %s in %s %s ", /* open-ended line */
 400                  reason, STATE2TXT, STATUS2TXT);
 401
 402         /*
 403          * Per the IPMI spec, retries are based on the sequence number
 404          * known only to this module, so manage a restart here.
 405          */
 406         (bt->error_retries)++;
 407         if (bt->error_retries < bt->BT_CAP_retries) {
 408                 pr_cont("%d retries left\n",
 409                         bt->BT_CAP_retries - bt->error_retries);
 410                 bt->state = BT_STATE_RESTART;
 411                 return SI_SM_CALL_WITHOUT_DELAY;
 412         }
 413
 414         dev_warn(bt->io->dev, "failed %d retries, sending error response\n",
 415                  bt->BT_CAP_retries);
 416         if (!bt->nonzero_status)
 417                 dev_err(bt->io->dev, "stuck, try power cycle\n");
 418
 419         /* this is most likely during insmod */
 420         else if (bt->seq <= (unsigned char)(bt->BT_CAP_retries & 0xFF)) {
 421                 dev_warn(bt->io->dev, "BT reset (takes 5 secs)\n");
 422                 bt->state = BT_STATE_RESET1;
 423                 return SI_SM_CALL_WITHOUT_DELAY;
 424         }
 425
 426         /*
 427          * Concoct a useful error message, set up the next state, and
 428          * be done with this sequence.
 429          */
 430
 431         bt->state = BT_STATE_IDLE;
 432         switch (cCode) {
 433         case IPMI_TIMEOUT_ERR:
 434                 if (status & BT_B_BUSY) {
 435                         cCode = IPMI_NODE_BUSY_ERR;
 436                         bt->state = BT_STATE_LONG_BUSY;
 437                 }
 438                 break;
 439         default:
 440                 break;
 441         }
 442         force_result(bt, cCode);
 443         return SI_SM_TRANSACTION_COMPLETE;
 444 }
 445
 446 /* Check status and (usually) take action and change this state machine. */
 447
 448 static enum si_sm_result bt_event(struct si_sm_data *bt, long time)
 449 {
 450         unsigned char status;
 451         static enum bt_states last_printed = BT_STATE_PRINTME;
 452         int i;
 453
 454         status = BT_STATUS;
 455         bt->nonzero_status |= status;
 456         if ((bt_debug & BT_DEBUG_STATES) && (bt->state != last_printed)) {
 457                 dev_dbg(bt->io->dev, "BT: %s %s TO=%ld - %ld\n",
 458                         STATE2TXT,
 459                         STATUS2TXT,
 460                         bt->timeout,
 461                         time);
 462                 last_printed = bt->state;
 463         }
 464
 465         /*
 466          * Commands that time out may still (eventually) provide a response.
 467          * This stale response will get in the way of a new response so remove
 468          * it if possible (hopefully during IDLE).  Even if it comes up later
 469          * it will be rejected by its (now-forgotten) seq number.
 470          */
 471
 472         if ((bt->state < BT_STATE_WRITE_BYTES) && (status & BT_B2H_ATN)) {
 473                 drain_BMC2HOST(bt);
 474                 BT_SI_SM_RETURN(SI_SM_CALL_WITH_DELAY);
 475         }
 476
 477         if ((bt->state != BT_STATE_IDLE) &&
 478             (bt->state <  BT_STATE_PRINTME)) {
 479                 /* check timeout */
 480                 bt->timeout -= time;
 481                 if ((bt->timeout < 0) && (bt->state < BT_STATE_RESET1))
 482                         return error_recovery(bt,
 483                                               status,
 484                                               IPMI_TIMEOUT_ERR);
 485         }
 486
 487         switch (bt->state) {
 488
 489         /*
 490          * Idle state first checks for asynchronous messages from another
 491          * channel, then does some opportunistic housekeeping.
 492          */
 493
 494         case BT_STATE_IDLE:
 495                 if (status & BT_SMS_ATN) {
 496                         BT_CONTROL(BT_SMS_ATN); /* clear it */
 497                         return SI_SM_ATTN;
 498                 }
 499
 500                 if (status & BT_H_BUSY)         /* clear a leftover H_BUSY */
 501                         BT_CONTROL(BT_H_BUSY);
 502
 503                 BT_SI_SM_RETURN(SI_SM_IDLE);
 504
 505         case BT_STATE_XACTION_START:
 506                 if (status & (BT_B_BUSY | BT_H2B_ATN))
 507                         BT_SI_SM_RETURN(SI_SM_CALL_WITH_DELAY);
 508                 if (BT_STATUS & BT_H_BUSY)
 509                         BT_CONTROL(BT_H_BUSY);  /* force clear */
 510                 BT_STATE_CHANGE(BT_STATE_WRITE_BYTES,
 511                                 SI_SM_CALL_WITHOUT_DELAY);
 512
 513         case BT_STATE_WRITE_BYTES:
 514                 if (status & BT_H_BUSY)
 515                         BT_CONTROL(BT_H_BUSY);  /* clear */
 516                 BT_CONTROL(BT_CLR_WR_PTR);
 517                 write_all_bytes(bt);
 518                 BT_CONTROL(BT_H2B_ATN); /* can clear too fast to catch */
 519                 BT_STATE_CHANGE(BT_STATE_WRITE_CONSUME,
 520                                 SI_SM_CALL_WITHOUT_DELAY);
 521
 522         case BT_STATE_WRITE_CONSUME:
 523                 if (status & (BT_B_BUSY | BT_H2B_ATN))
 524                         BT_SI_SM_RETURN(SI_SM_CALL_WITH_DELAY);
 525                 BT_STATE_CHANGE(BT_STATE_READ_WAIT,
 526                                 SI_SM_CALL_WITHOUT_DELAY);
 527
 528         /* Spinning hard can suppress B2H_ATN and force a timeout */
 529
 530         case BT_STATE_READ_WAIT:
 531                 if (!(status & BT_B2H_ATN))
 532                         BT_SI_SM_RETURN(SI_SM_CALL_WITH_DELAY);
 533                 BT_CONTROL(BT_H_BUSY);          /* set */
 534
 535                 /*
 536                  * Uncached, ordered writes should just proceed serially but
 537                  * some BMCs don't clear B2H_ATN with one hit.  Fast-path a
 538                  * workaround without too much penalty to the general case.
 539                  */
 540
 541                 BT_CONTROL(BT_B2H_ATN);         /* clear it to ACK the BMC */
 542                 BT_STATE_CHANGE(BT_STATE_CLEAR_B2H,
 543                                 SI_SM_CALL_WITHOUT_DELAY);
 544
 545         case BT_STATE_CLEAR_B2H:
 546                 if (status & BT_B2H_ATN) {
 547                         /* keep hitting it */
 548                         BT_CONTROL(BT_B2H_ATN);
 549                         BT_SI_SM_RETURN(SI_SM_CALL_WITH_DELAY);
 550                 }
 551                 BT_STATE_CHANGE(BT_STATE_READ_BYTES,
 552                                 SI_SM_CALL_WITHOUT_DELAY);
 553
 554         case BT_STATE_READ_BYTES:
 555                 if (!(status & BT_H_BUSY))
 556                         /* check in case of retry */
 557                         BT_CONTROL(BT_H_BUSY);
 558                 BT_CONTROL(BT_CLR_RD_PTR);      /* start of BMC2HOST buffer */
 559                 i = read_all_bytes(bt);         /* true == packet seq match */
 560                 BT_CONTROL(BT_H_BUSY);          /* NOW clear */
 561                 if (!i)                         /* Not my message */
 562                         BT_STATE_CHANGE(BT_STATE_READ_WAIT,
 563                                         SI_SM_CALL_WITHOUT_DELAY);
 564                 bt->state = bt->complete;
 565                 return bt->state == BT_STATE_IDLE ?     /* where to next? */
 566                         SI_SM_TRANSACTION_COMPLETE :    /* normal */
 567                         SI_SM_CALL_WITHOUT_DELAY;       /* Startup magic */
 568
 569         case BT_STATE_LONG_BUSY:        /* For example: after FW update */
 570                 if (!(status & BT_B_BUSY)) {
 571                         reset_flags(bt);        /* next state is now IDLE */
 572                         bt_init_data(bt, bt->io);
 573                 }
 574                 return SI_SM_CALL_WITH_DELAY;   /* No repeat printing */
 575
 576         case BT_STATE_RESET1:
 577                 reset_flags(bt);
 578                 drain_BMC2HOST(bt);
 579                 BT_STATE_CHANGE(BT_STATE_RESET2,
 580                                 SI_SM_CALL_WITH_DELAY);
 581
 582         case BT_STATE_RESET2:           /* Send a soft reset */
 583                 BT_CONTROL(BT_CLR_WR_PTR);
 584                 HOST2BMC(3);            /* number of bytes following */
 585                 HOST2BMC(0x18);         /* NetFn/LUN == Application, LUN 0 */
 586                 HOST2BMC(42);           /* Sequence number */
 587                 HOST2BMC(3);            /* Cmd == Soft reset */
 588                 BT_CONTROL(BT_H2B_ATN);
 589                 bt->timeout = BT_RESET_DELAY * USEC_PER_SEC;
 590                 BT_STATE_CHANGE(BT_STATE_RESET3,
 591                                 SI_SM_CALL_WITH_DELAY);
 592
 593         case BT_STATE_RESET3:           /* Hold off everything for a bit */
 594                 if (bt->timeout > 0)
 595                         return SI_SM_CALL_WITH_DELAY;
 596                 drain_BMC2HOST(bt);
 597                 BT_STATE_CHANGE(BT_STATE_RESTART,
 598                                 SI_SM_CALL_WITH_DELAY);
 599
 600         case BT_STATE_RESTART:          /* don't reset retries or seq! */
 601                 bt->read_count = 0;
 602                 bt->nonzero_status = 0;
 603                 bt->timeout = bt->BT_CAP_req2rsp;
 604                 BT_STATE_CHANGE(BT_STATE_XACTION_START,
 605                                 SI_SM_CALL_WITH_DELAY);
 606
 607         default:        /* should never occur */
 608                 return error_recovery(bt,
 609                                       status,
 610                                       IPMI_ERR_UNSPECIFIED);
 611         }
 612         return SI_SM_CALL_WITH_DELAY;
 613 }
 614
 615 static int bt_detect(struct si_sm_data *bt)
 616 {
 617         unsigned char GetBT_CAP[] = { 0x18, 0x36 };
 618         unsigned char BT_CAP[8];
 619         enum si_sm_result smi_result;
 620         int rv;
 621
 622         /*
 623          * It's impossible for the BT status and interrupt registers to be
 624          * all 1's, (assuming a properly functioning, self-initialized BMC)
 625          * but that's what you get from reading a bogus address, so we
 626          * test that first.  The calling routine uses negative logic.
 627          */
 628
 629         if ((BT_STATUS == 0xFF) && (BT_INTMASK_R == 0xFF))
 630                 return 1;
 631         reset_flags(bt);
 632
 633         /*
 634          * Try getting the BT capabilities here.
 635          */
 636         rv = bt_start_transaction(bt, GetBT_CAP, sizeof(GetBT_CAP));
 637         if (rv) {
 638                 dev_warn(bt->io->dev,
 639                          "Can't start capabilities transaction: %d\n", rv);
 640                 goto out_no_bt_cap;
 641         }
 642
 643         smi_result = SI_SM_CALL_WITHOUT_DELAY;
 644         for (;;) {
 645                 if (smi_result == SI_SM_CALL_WITH_DELAY ||
 646                     smi_result == SI_SM_CALL_WITH_TICK_DELAY) {
 647                         schedule_timeout_uninterruptible(1);
 648                         smi_result = bt_event(bt, jiffies_to_usecs(1));
 649                 } else if (smi_result == SI_SM_CALL_WITHOUT_DELAY) {
 650                         smi_result = bt_event(bt, 0);
 651                 } else
 652                         break;
 653         }
 654
 655         rv = bt_get_result(bt, BT_CAP, sizeof(BT_CAP));
 656         bt_init_data(bt, bt->io);
 657         if (rv < 8) {
 658                 dev_warn(bt->io->dev, "bt cap response too short: %d\n", rv);
 659                 goto out_no_bt_cap;
 660         }
 661
 662         if (BT_CAP[2]) {
 663                 dev_warn(bt->io->dev, "Error fetching bt cap: %x\n", BT_CAP[2]);
 664 out_no_bt_cap:
 665                 dev_warn(bt->io->dev, "using default values\n");
 666         } else {
 667                 bt->BT_CAP_req2rsp = BT_CAP[6] * USEC_PER_SEC;
 668                 bt->BT_CAP_retries = BT_CAP[7];
 669         }
 670
 671         dev_info(bt->io->dev, "req2rsp=%ld secs retries=%d\n",
 672                  bt->BT_CAP_req2rsp / USEC_PER_SEC, bt->BT_CAP_retries);
 673
 674         return 0;
 675 }
 676
 677 static void bt_cleanup(struct si_sm_data *bt)
 678 {
 679 }
 680
 681 static int bt_size(void)
 682 {
 683         return sizeof(struct si_sm_data);
 684 }
 685
 686 const struct si_sm_handlers bt_smi_handlers = {
 687         .init_data              = bt_init_data,
 688         .start_transaction      = bt_start_transaction,
 689         .get_result             = bt_get_result,
 690         .event                  = bt_event,
 691         .detect                 = bt_detect,
 692         .cleanup                = bt_cleanup,
 693         .size                   = bt_size,
 694 };