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