1 /* 2 * ipmi_kcs_sm.c 3 * 4 * State machine for handling IPMI KCS interfaces. 5 * 6 * Author: MontaVista Software, Inc. 7 * Corey Minyard <minyard@mvista.com> 8 * source@mvista.com 9 * 10 * Copyright 2002 MontaVista Software Inc. 11 * 12 * This program is free software; you can redistribute it and/or modify it 13 * under the terms of the GNU General Public License as published by the 14 * Free Software Foundation; either version 2 of the License, or (at your 15 * option) any later version. 16 * 17 * 18 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED 19 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 20 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 23 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 24 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 25 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR 26 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE 27 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 * 29 * You should have received a copy of the GNU General Public License along 30 * with this program; if not, write to the Free Software Foundation, Inc., 31 * 675 Mass Ave, Cambridge, MA 02139, USA. 32 */ 33 34 /* 35 * This state machine is taken from the state machine in the IPMI spec, 36 * pretty much verbatim. If you have questions about the states, see 37 * that document. 38 */ 39 40 #include <linux/kernel.h> /* For printk. */ 41 #include <linux/module.h> 42 #include <linux/moduleparam.h> 43 #include <linux/string.h> 44 #include <linux/jiffies.h> 45 #include <linux/ipmi_msgdefs.h> /* for completion codes */ 46 #include "ipmi_si_sm.h" 47 48 /* kcs_debug is a bit-field 49 * KCS_DEBUG_ENABLE - turned on for now 50 * KCS_DEBUG_MSG - commands and their responses 51 * KCS_DEBUG_STATES - state machine 52 */ 53 #define KCS_DEBUG_STATES 4 54 #define KCS_DEBUG_MSG 2 55 #define KCS_DEBUG_ENABLE 1 56 57 static int kcs_debug; 58 module_param(kcs_debug, int, 0644); 59 MODULE_PARM_DESC(kcs_debug, "debug bitmask, 1=enable, 2=messages, 4=states"); 60 61 /* The states the KCS driver may be in. */ 62 enum kcs_states { 63 KCS_IDLE, /* The KCS interface is currently 64 doing nothing. */ 65 KCS_START_OP, /* We are starting an operation. The 66 data is in the output buffer, but 67 nothing has been done to the 68 interface yet. This was added to 69 the state machine in the spec to 70 wait for the initial IBF. */ 71 KCS_WAIT_WRITE_START, /* We have written a write cmd to the 72 interface. */ 73 KCS_WAIT_WRITE, /* We are writing bytes to the 74 interface. */ 75 KCS_WAIT_WRITE_END, /* We have written the write end cmd 76 to the interface, and still need to 77 write the last byte. */ 78 KCS_WAIT_READ, /* We are waiting to read data from 79 the interface. */ 80 KCS_ERROR0, /* State to transition to the error 81 handler, this was added to the 82 state machine in the spec to be 83 sure IBF was there. */ 84 KCS_ERROR1, /* First stage error handler, wait for 85 the interface to respond. */ 86 KCS_ERROR2, /* The abort cmd has been written, 87 wait for the interface to 88 respond. */ 89 KCS_ERROR3, /* We wrote some data to the 90 interface, wait for it to switch to 91 read mode. */ 92 KCS_HOSED /* The hardware failed to follow the 93 state machine. */ 94 }; 95 96 #define MAX_KCS_READ_SIZE 80 97 #define MAX_KCS_WRITE_SIZE 80 98 99 /* Timeouts in microseconds. */ 100 #define IBF_RETRY_TIMEOUT 1000000 101 #define OBF_RETRY_TIMEOUT 1000000 102 #define MAX_ERROR_RETRIES 10 103 #define ERROR0_OBF_WAIT_JIFFIES (2*HZ) 104 105 struct si_sm_data 106 { 107 enum kcs_states state; 108 struct si_sm_io *io; 109 unsigned char write_data[MAX_KCS_WRITE_SIZE]; 110 int write_pos; 111 int write_count; 112 int orig_write_count; 113 unsigned char read_data[MAX_KCS_READ_SIZE]; 114 int read_pos; 115 int truncated; 116 117 unsigned int error_retries; 118 long ibf_timeout; 119 long obf_timeout; 120 unsigned long error0_timeout; 121 }; 122 123 static unsigned int init_kcs_data(struct si_sm_data *kcs, 124 struct si_sm_io *io) 125 { 126 kcs->state = KCS_IDLE; 127 kcs->io = io; 128 kcs->write_pos = 0; 129 kcs->write_count = 0; 130 kcs->orig_write_count = 0; 131 kcs->read_pos = 0; 132 kcs->error_retries = 0; 133 kcs->truncated = 0; 134 kcs->ibf_timeout = IBF_RETRY_TIMEOUT; 135 kcs->obf_timeout = OBF_RETRY_TIMEOUT; 136 137 /* Reserve 2 I/O bytes. */ 138 return 2; 139 } 140 141 static inline unsigned char read_status(struct si_sm_data *kcs) 142 { 143 return kcs->io->inputb(kcs->io, 1); 144 } 145 146 static inline unsigned char read_data(struct si_sm_data *kcs) 147 { 148 return kcs->io->inputb(kcs->io, 0); 149 } 150 151 static inline void write_cmd(struct si_sm_data *kcs, unsigned char data) 152 { 153 kcs->io->outputb(kcs->io, 1, data); 154 } 155 156 static inline void write_data(struct si_sm_data *kcs, unsigned char data) 157 { 158 kcs->io->outputb(kcs->io, 0, data); 159 } 160 161 /* Control codes. */ 162 #define KCS_GET_STATUS_ABORT 0x60 163 #define KCS_WRITE_START 0x61 164 #define KCS_WRITE_END 0x62 165 #define KCS_READ_BYTE 0x68 166 167 /* Status bits. */ 168 #define GET_STATUS_STATE(status) (((status) >> 6) & 0x03) 169 #define KCS_IDLE_STATE 0 170 #define KCS_READ_STATE 1 171 #define KCS_WRITE_STATE 2 172 #define KCS_ERROR_STATE 3 173 #define GET_STATUS_ATN(status) ((status) & 0x04) 174 #define GET_STATUS_IBF(status) ((status) & 0x02) 175 #define GET_STATUS_OBF(status) ((status) & 0x01) 176 177 178 static inline void write_next_byte(struct si_sm_data *kcs) 179 { 180 write_data(kcs, kcs->write_data[kcs->write_pos]); 181 (kcs->write_pos)++; 182 (kcs->write_count)--; 183 } 184 185 static inline void start_error_recovery(struct si_sm_data *kcs, char *reason) 186 { 187 (kcs->error_retries)++; 188 if (kcs->error_retries > MAX_ERROR_RETRIES) { 189 if (kcs_debug & KCS_DEBUG_ENABLE) 190 printk(KERN_DEBUG "ipmi_kcs_sm: kcs hosed: %s\n", reason); 191 kcs->state = KCS_HOSED; 192 } else { 193 kcs->error0_timeout = jiffies + ERROR0_OBF_WAIT_JIFFIES; 194 kcs->state = KCS_ERROR0; 195 } 196 } 197 198 static inline void read_next_byte(struct si_sm_data *kcs) 199 { 200 if (kcs->read_pos >= MAX_KCS_READ_SIZE) { 201 /* Throw the data away and mark it truncated. */ 202 read_data(kcs); 203 kcs->truncated = 1; 204 } else { 205 kcs->read_data[kcs->read_pos] = read_data(kcs); 206 (kcs->read_pos)++; 207 } 208 write_data(kcs, KCS_READ_BYTE); 209 } 210 211 static inline int check_ibf(struct si_sm_data *kcs, unsigned char status, 212 long time) 213 { 214 if (GET_STATUS_IBF(status)) { 215 kcs->ibf_timeout -= time; 216 if (kcs->ibf_timeout < 0) { 217 start_error_recovery(kcs, "IBF not ready in time"); 218 kcs->ibf_timeout = IBF_RETRY_TIMEOUT; 219 return 1; 220 } 221 return 0; 222 } 223 kcs->ibf_timeout = IBF_RETRY_TIMEOUT; 224 return 1; 225 } 226 227 static inline int check_obf(struct si_sm_data *kcs, unsigned char status, 228 long time) 229 { 230 if (!GET_STATUS_OBF(status)) { 231 kcs->obf_timeout -= time; 232 if (kcs->obf_timeout < 0) { 233 start_error_recovery(kcs, "OBF not ready in time"); 234 return 1; 235 } 236 return 0; 237 } 238 kcs->obf_timeout = OBF_RETRY_TIMEOUT; 239 return 1; 240 } 241 242 static void clear_obf(struct si_sm_data *kcs, unsigned char status) 243 { 244 if (GET_STATUS_OBF(status)) 245 read_data(kcs); 246 } 247 248 static void restart_kcs_transaction(struct si_sm_data *kcs) 249 { 250 kcs->write_count = kcs->orig_write_count; 251 kcs->write_pos = 0; 252 kcs->read_pos = 0; 253 kcs->state = KCS_WAIT_WRITE_START; 254 kcs->ibf_timeout = IBF_RETRY_TIMEOUT; 255 kcs->obf_timeout = OBF_RETRY_TIMEOUT; 256 write_cmd(kcs, KCS_WRITE_START); 257 } 258 259 static int start_kcs_transaction(struct si_sm_data *kcs, unsigned char *data, 260 unsigned int size) 261 { 262 unsigned int i; 263 264 if ((size < 2) || (size > MAX_KCS_WRITE_SIZE)) { 265 return -1; 266 } 267 if ((kcs->state != KCS_IDLE) && (kcs->state != KCS_HOSED)) { 268 return -2; 269 } 270 if (kcs_debug & KCS_DEBUG_MSG) { 271 printk(KERN_DEBUG "start_kcs_transaction -"); 272 for (i = 0; i < size; i ++) { 273 printk(" %02x", (unsigned char) (data [i])); 274 } 275 printk ("\n"); 276 } 277 kcs->error_retries = 0; 278 memcpy(kcs->write_data, data, size); 279 kcs->write_count = size; 280 kcs->orig_write_count = size; 281 kcs->write_pos = 0; 282 kcs->read_pos = 0; 283 kcs->state = KCS_START_OP; 284 kcs->ibf_timeout = IBF_RETRY_TIMEOUT; 285 kcs->obf_timeout = OBF_RETRY_TIMEOUT; 286 return 0; 287 } 288 289 static int get_kcs_result(struct si_sm_data *kcs, unsigned char *data, 290 unsigned int length) 291 { 292 if (length < kcs->read_pos) { 293 kcs->read_pos = length; 294 kcs->truncated = 1; 295 } 296 297 memcpy(data, kcs->read_data, kcs->read_pos); 298 299 if ((length >= 3) && (kcs->read_pos < 3)) { 300 /* Guarantee that we return at least 3 bytes, with an 301 error in the third byte if it is too short. */ 302 data[2] = IPMI_ERR_UNSPECIFIED; 303 kcs->read_pos = 3; 304 } 305 if (kcs->truncated) { 306 /* Report a truncated error. We might overwrite 307 another error, but that's too bad, the user needs 308 to know it was truncated. */ 309 data[2] = IPMI_ERR_MSG_TRUNCATED; 310 kcs->truncated = 0; 311 } 312 313 return kcs->read_pos; 314 } 315 316 /* This implements the state machine defined in the IPMI manual, see 317 that for details on how this works. Divide that flowchart into 318 sections delimited by "Wait for IBF" and this will become clear. */ 319 static enum si_sm_result kcs_event(struct si_sm_data *kcs, long time) 320 { 321 unsigned char status; 322 unsigned char state; 323 324 status = read_status(kcs); 325 326 if (kcs_debug & KCS_DEBUG_STATES) 327 printk(KERN_DEBUG "KCS: State = %d, %x\n", kcs->state, status); 328 329 /* All states wait for ibf, so just do it here. */ 330 if (!check_ibf(kcs, status, time)) 331 return SI_SM_CALL_WITH_DELAY; 332 333 /* Just about everything looks at the KCS state, so grab that, too. */ 334 state = GET_STATUS_STATE(status); 335 336 switch (kcs->state) { 337 case KCS_IDLE: 338 /* If there's and interrupt source, turn it off. */ 339 clear_obf(kcs, status); 340 341 if (GET_STATUS_ATN(status)) 342 return SI_SM_ATTN; 343 else 344 return SI_SM_IDLE; 345 346 case KCS_START_OP: 347 if (state != KCS_IDLE) { 348 start_error_recovery(kcs, 349 "State machine not idle at start"); 350 break; 351 } 352 353 clear_obf(kcs, status); 354 write_cmd(kcs, KCS_WRITE_START); 355 kcs->state = KCS_WAIT_WRITE_START; 356 break; 357 358 case KCS_WAIT_WRITE_START: 359 if (state != KCS_WRITE_STATE) { 360 start_error_recovery( 361 kcs, 362 "Not in write state at write start"); 363 break; 364 } 365 read_data(kcs); 366 if (kcs->write_count == 1) { 367 write_cmd(kcs, KCS_WRITE_END); 368 kcs->state = KCS_WAIT_WRITE_END; 369 } else { 370 write_next_byte(kcs); 371 kcs->state = KCS_WAIT_WRITE; 372 } 373 break; 374 375 case KCS_WAIT_WRITE: 376 if (state != KCS_WRITE_STATE) { 377 start_error_recovery(kcs, 378 "Not in write state for write"); 379 break; 380 } 381 clear_obf(kcs, status); 382 if (kcs->write_count == 1) { 383 write_cmd(kcs, KCS_WRITE_END); 384 kcs->state = KCS_WAIT_WRITE_END; 385 } else { 386 write_next_byte(kcs); 387 } 388 break; 389 390 case KCS_WAIT_WRITE_END: 391 if (state != KCS_WRITE_STATE) { 392 start_error_recovery(kcs, 393 "Not in write state for write end"); 394 break; 395 } 396 clear_obf(kcs, status); 397 write_next_byte(kcs); 398 kcs->state = KCS_WAIT_READ; 399 break; 400 401 case KCS_WAIT_READ: 402 if ((state != KCS_READ_STATE) && (state != KCS_IDLE_STATE)) { 403 start_error_recovery( 404 kcs, 405 "Not in read or idle in read state"); 406 break; 407 } 408 409 if (state == KCS_READ_STATE) { 410 if (!check_obf(kcs, status, time)) 411 return SI_SM_CALL_WITH_DELAY; 412 read_next_byte(kcs); 413 } else { 414 /* We don't implement this exactly like the state 415 machine in the spec. Some broken hardware 416 does not write the final dummy byte to the 417 read register. Thus obf will never go high 418 here. We just go straight to idle, and we 419 handle clearing out obf in idle state if it 420 happens to come in. */ 421 clear_obf(kcs, status); 422 kcs->orig_write_count = 0; 423 kcs->state = KCS_IDLE; 424 return SI_SM_TRANSACTION_COMPLETE; 425 } 426 break; 427 428 case KCS_ERROR0: 429 clear_obf(kcs, status); 430 status = read_status(kcs); 431 if (GET_STATUS_OBF(status)) /* controller isn't responding */ 432 if (time_before(jiffies, kcs->error0_timeout)) 433 return SI_SM_CALL_WITH_TICK_DELAY; 434 write_cmd(kcs, KCS_GET_STATUS_ABORT); 435 kcs->state = KCS_ERROR1; 436 break; 437 438 case KCS_ERROR1: 439 clear_obf(kcs, status); 440 write_data(kcs, 0); 441 kcs->state = KCS_ERROR2; 442 break; 443 444 case KCS_ERROR2: 445 if (state != KCS_READ_STATE) { 446 start_error_recovery(kcs, 447 "Not in read state for error2"); 448 break; 449 } 450 if (!check_obf(kcs, status, time)) 451 return SI_SM_CALL_WITH_DELAY; 452 453 clear_obf(kcs, status); 454 write_data(kcs, KCS_READ_BYTE); 455 kcs->state = KCS_ERROR3; 456 break; 457 458 case KCS_ERROR3: 459 if (state != KCS_IDLE_STATE) { 460 start_error_recovery(kcs, 461 "Not in idle state for error3"); 462 break; 463 } 464 465 if (!check_obf(kcs, status, time)) 466 return SI_SM_CALL_WITH_DELAY; 467 468 clear_obf(kcs, status); 469 if (kcs->orig_write_count) { 470 restart_kcs_transaction(kcs); 471 } else { 472 kcs->state = KCS_IDLE; 473 return SI_SM_TRANSACTION_COMPLETE; 474 } 475 break; 476 477 case KCS_HOSED: 478 break; 479 } 480 481 if (kcs->state == KCS_HOSED) { 482 init_kcs_data(kcs, kcs->io); 483 return SI_SM_HOSED; 484 } 485 486 return SI_SM_CALL_WITHOUT_DELAY; 487 } 488 489 static int kcs_size(void) 490 { 491 return sizeof(struct si_sm_data); 492 } 493 494 static int kcs_detect(struct si_sm_data *kcs) 495 { 496 /* It's impossible for the KCS status register to be all 1's, 497 (assuming a properly functioning, self-initialized BMC) 498 but that's what you get from reading a bogus address, so we 499 test that first. */ 500 if (read_status(kcs) == 0xff) 501 return 1; 502 503 return 0; 504 } 505 506 static void kcs_cleanup(struct si_sm_data *kcs) 507 { 508 } 509 510 struct si_sm_handlers kcs_smi_handlers = 511 { 512 .init_data = init_kcs_data, 513 .start_transaction = start_kcs_transaction, 514 .get_result = get_kcs_result, 515 .event = kcs_event, 516 .detect = kcs_detect, 517 .cleanup = kcs_cleanup, 518 .size = kcs_size, 519 }; 520