Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 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/string.h> |
| 42 | #include <linux/ipmi_msgdefs.h> /* for completion codes */ |
| 43 | #include "ipmi_si_sm.h" |
| 44 | |
| 45 | #define IPMI_KCS_VERSION "v33" |
| 46 | |
| 47 | /* Set this if you want a printout of why the state machine was hosed |
| 48 | when it gets hosed. */ |
| 49 | #define DEBUG_HOSED_REASON |
| 50 | |
| 51 | /* Print the state machine state on entry every time. */ |
| 52 | #undef DEBUG_STATE |
| 53 | |
| 54 | /* The states the KCS driver may be in. */ |
| 55 | enum kcs_states { |
| 56 | KCS_IDLE, /* The KCS interface is currently |
| 57 | doing nothing. */ |
| 58 | KCS_START_OP, /* We are starting an operation. The |
| 59 | data is in the output buffer, but |
| 60 | nothing has been done to the |
| 61 | interface yet. This was added to |
| 62 | the state machine in the spec to |
| 63 | wait for the initial IBF. */ |
| 64 | KCS_WAIT_WRITE_START, /* We have written a write cmd to the |
| 65 | interface. */ |
| 66 | KCS_WAIT_WRITE, /* We are writing bytes to the |
| 67 | interface. */ |
| 68 | KCS_WAIT_WRITE_END, /* We have written the write end cmd |
| 69 | to the interface, and still need to |
| 70 | write the last byte. */ |
| 71 | KCS_WAIT_READ, /* We are waiting to read data from |
| 72 | the interface. */ |
| 73 | KCS_ERROR0, /* State to transition to the error |
| 74 | handler, this was added to the |
| 75 | state machine in the spec to be |
| 76 | sure IBF was there. */ |
| 77 | KCS_ERROR1, /* First stage error handler, wait for |
| 78 | the interface to respond. */ |
| 79 | KCS_ERROR2, /* The abort cmd has been written, |
| 80 | wait for the interface to |
| 81 | respond. */ |
| 82 | KCS_ERROR3, /* We wrote some data to the |
| 83 | interface, wait for it to switch to |
| 84 | read mode. */ |
| 85 | KCS_HOSED /* The hardware failed to follow the |
| 86 | state machine. */ |
| 87 | }; |
| 88 | |
| 89 | #define MAX_KCS_READ_SIZE 80 |
| 90 | #define MAX_KCS_WRITE_SIZE 80 |
| 91 | |
| 92 | /* Timeouts in microseconds. */ |
| 93 | #define IBF_RETRY_TIMEOUT 1000000 |
| 94 | #define OBF_RETRY_TIMEOUT 1000000 |
| 95 | #define MAX_ERROR_RETRIES 10 |
| 96 | |
| 97 | struct si_sm_data |
| 98 | { |
| 99 | enum kcs_states state; |
| 100 | struct si_sm_io *io; |
| 101 | unsigned char write_data[MAX_KCS_WRITE_SIZE]; |
| 102 | int write_pos; |
| 103 | int write_count; |
| 104 | int orig_write_count; |
| 105 | unsigned char read_data[MAX_KCS_READ_SIZE]; |
| 106 | int read_pos; |
| 107 | int truncated; |
| 108 | |
| 109 | unsigned int error_retries; |
| 110 | long ibf_timeout; |
| 111 | long obf_timeout; |
| 112 | }; |
| 113 | |
| 114 | static unsigned int init_kcs_data(struct si_sm_data *kcs, |
| 115 | struct si_sm_io *io) |
| 116 | { |
| 117 | kcs->state = KCS_IDLE; |
| 118 | kcs->io = io; |
| 119 | kcs->write_pos = 0; |
| 120 | kcs->write_count = 0; |
| 121 | kcs->orig_write_count = 0; |
| 122 | kcs->read_pos = 0; |
| 123 | kcs->error_retries = 0; |
| 124 | kcs->truncated = 0; |
| 125 | kcs->ibf_timeout = IBF_RETRY_TIMEOUT; |
| 126 | kcs->obf_timeout = OBF_RETRY_TIMEOUT; |
| 127 | |
| 128 | /* Reserve 2 I/O bytes. */ |
| 129 | return 2; |
| 130 | } |
| 131 | |
| 132 | static inline unsigned char read_status(struct si_sm_data *kcs) |
| 133 | { |
| 134 | return kcs->io->inputb(kcs->io, 1); |
| 135 | } |
| 136 | |
| 137 | static inline unsigned char read_data(struct si_sm_data *kcs) |
| 138 | { |
| 139 | return kcs->io->inputb(kcs->io, 0); |
| 140 | } |
| 141 | |
| 142 | static inline void write_cmd(struct si_sm_data *kcs, unsigned char data) |
| 143 | { |
| 144 | kcs->io->outputb(kcs->io, 1, data); |
| 145 | } |
| 146 | |
| 147 | static inline void write_data(struct si_sm_data *kcs, unsigned char data) |
| 148 | { |
| 149 | kcs->io->outputb(kcs->io, 0, data); |
| 150 | } |
| 151 | |
| 152 | /* Control codes. */ |
| 153 | #define KCS_GET_STATUS_ABORT 0x60 |
| 154 | #define KCS_WRITE_START 0x61 |
| 155 | #define KCS_WRITE_END 0x62 |
| 156 | #define KCS_READ_BYTE 0x68 |
| 157 | |
| 158 | /* Status bits. */ |
| 159 | #define GET_STATUS_STATE(status) (((status) >> 6) & 0x03) |
| 160 | #define KCS_IDLE_STATE 0 |
| 161 | #define KCS_READ_STATE 1 |
| 162 | #define KCS_WRITE_STATE 2 |
| 163 | #define KCS_ERROR_STATE 3 |
| 164 | #define GET_STATUS_ATN(status) ((status) & 0x04) |
| 165 | #define GET_STATUS_IBF(status) ((status) & 0x02) |
| 166 | #define GET_STATUS_OBF(status) ((status) & 0x01) |
| 167 | |
| 168 | |
| 169 | static inline void write_next_byte(struct si_sm_data *kcs) |
| 170 | { |
| 171 | write_data(kcs, kcs->write_data[kcs->write_pos]); |
| 172 | (kcs->write_pos)++; |
| 173 | (kcs->write_count)--; |
| 174 | } |
| 175 | |
| 176 | static inline void start_error_recovery(struct si_sm_data *kcs, char *reason) |
| 177 | { |
| 178 | (kcs->error_retries)++; |
| 179 | if (kcs->error_retries > MAX_ERROR_RETRIES) { |
| 180 | #ifdef DEBUG_HOSED_REASON |
| 181 | printk("ipmi_kcs_sm: kcs hosed: %s\n", reason); |
| 182 | #endif |
| 183 | kcs->state = KCS_HOSED; |
| 184 | } else { |
| 185 | kcs->state = KCS_ERROR0; |
| 186 | } |
| 187 | } |
| 188 | |
| 189 | static inline void read_next_byte(struct si_sm_data *kcs) |
| 190 | { |
| 191 | if (kcs->read_pos >= MAX_KCS_READ_SIZE) { |
| 192 | /* Throw the data away and mark it truncated. */ |
| 193 | read_data(kcs); |
| 194 | kcs->truncated = 1; |
| 195 | } else { |
| 196 | kcs->read_data[kcs->read_pos] = read_data(kcs); |
| 197 | (kcs->read_pos)++; |
| 198 | } |
| 199 | write_data(kcs, KCS_READ_BYTE); |
| 200 | } |
| 201 | |
| 202 | static inline int check_ibf(struct si_sm_data *kcs, unsigned char status, |
| 203 | long time) |
| 204 | { |
| 205 | if (GET_STATUS_IBF(status)) { |
| 206 | kcs->ibf_timeout -= time; |
| 207 | if (kcs->ibf_timeout < 0) { |
| 208 | start_error_recovery(kcs, "IBF not ready in time"); |
| 209 | kcs->ibf_timeout = IBF_RETRY_TIMEOUT; |
| 210 | return 1; |
| 211 | } |
| 212 | return 0; |
| 213 | } |
| 214 | kcs->ibf_timeout = IBF_RETRY_TIMEOUT; |
| 215 | return 1; |
| 216 | } |
| 217 | |
| 218 | static inline int check_obf(struct si_sm_data *kcs, unsigned char status, |
| 219 | long time) |
| 220 | { |
| 221 | if (! GET_STATUS_OBF(status)) { |
| 222 | kcs->obf_timeout -= time; |
| 223 | if (kcs->obf_timeout < 0) { |
| 224 | start_error_recovery(kcs, "OBF not ready in time"); |
| 225 | return 1; |
| 226 | } |
| 227 | return 0; |
| 228 | } |
| 229 | kcs->obf_timeout = OBF_RETRY_TIMEOUT; |
| 230 | return 1; |
| 231 | } |
| 232 | |
| 233 | static void clear_obf(struct si_sm_data *kcs, unsigned char status) |
| 234 | { |
| 235 | if (GET_STATUS_OBF(status)) |
| 236 | read_data(kcs); |
| 237 | } |
| 238 | |
| 239 | static void restart_kcs_transaction(struct si_sm_data *kcs) |
| 240 | { |
| 241 | kcs->write_count = kcs->orig_write_count; |
| 242 | kcs->write_pos = 0; |
| 243 | kcs->read_pos = 0; |
| 244 | kcs->state = KCS_WAIT_WRITE_START; |
| 245 | kcs->ibf_timeout = IBF_RETRY_TIMEOUT; |
| 246 | kcs->obf_timeout = OBF_RETRY_TIMEOUT; |
| 247 | write_cmd(kcs, KCS_WRITE_START); |
| 248 | } |
| 249 | |
| 250 | static int start_kcs_transaction(struct si_sm_data *kcs, unsigned char *data, |
| 251 | unsigned int size) |
| 252 | { |
| 253 | if ((size < 2) || (size > MAX_KCS_WRITE_SIZE)) { |
| 254 | return -1; |
| 255 | } |
| 256 | |
| 257 | if ((kcs->state != KCS_IDLE) && (kcs->state != KCS_HOSED)) { |
| 258 | return -2; |
| 259 | } |
| 260 | |
| 261 | kcs->error_retries = 0; |
| 262 | memcpy(kcs->write_data, data, size); |
| 263 | kcs->write_count = size; |
| 264 | kcs->orig_write_count = size; |
| 265 | kcs->write_pos = 0; |
| 266 | kcs->read_pos = 0; |
| 267 | kcs->state = KCS_START_OP; |
| 268 | kcs->ibf_timeout = IBF_RETRY_TIMEOUT; |
| 269 | kcs->obf_timeout = OBF_RETRY_TIMEOUT; |
| 270 | return 0; |
| 271 | } |
| 272 | |
| 273 | static int get_kcs_result(struct si_sm_data *kcs, unsigned char *data, |
| 274 | unsigned int length) |
| 275 | { |
| 276 | if (length < kcs->read_pos) { |
| 277 | kcs->read_pos = length; |
| 278 | kcs->truncated = 1; |
| 279 | } |
| 280 | |
| 281 | memcpy(data, kcs->read_data, kcs->read_pos); |
| 282 | |
| 283 | if ((length >= 3) && (kcs->read_pos < 3)) { |
| 284 | /* Guarantee that we return at least 3 bytes, with an |
| 285 | error in the third byte if it is too short. */ |
| 286 | data[2] = IPMI_ERR_UNSPECIFIED; |
| 287 | kcs->read_pos = 3; |
| 288 | } |
| 289 | if (kcs->truncated) { |
| 290 | /* Report a truncated error. We might overwrite |
| 291 | another error, but that's too bad, the user needs |
| 292 | to know it was truncated. */ |
| 293 | data[2] = IPMI_ERR_MSG_TRUNCATED; |
| 294 | kcs->truncated = 0; |
| 295 | } |
| 296 | |
| 297 | return kcs->read_pos; |
| 298 | } |
| 299 | |
| 300 | /* This implements the state machine defined in the IPMI manual, see |
| 301 | that for details on how this works. Divide that flowchart into |
| 302 | sections delimited by "Wait for IBF" and this will become clear. */ |
| 303 | static enum si_sm_result kcs_event(struct si_sm_data *kcs, long time) |
| 304 | { |
| 305 | unsigned char status; |
| 306 | unsigned char state; |
| 307 | |
| 308 | status = read_status(kcs); |
| 309 | |
| 310 | #ifdef DEBUG_STATE |
| 311 | printk(" State = %d, %x\n", kcs->state, status); |
| 312 | #endif |
| 313 | /* All states wait for ibf, so just do it here. */ |
| 314 | if (!check_ibf(kcs, status, time)) |
| 315 | return SI_SM_CALL_WITH_DELAY; |
| 316 | |
| 317 | /* Just about everything looks at the KCS state, so grab that, too. */ |
| 318 | state = GET_STATUS_STATE(status); |
| 319 | |
| 320 | switch (kcs->state) { |
| 321 | case KCS_IDLE: |
| 322 | /* If there's and interrupt source, turn it off. */ |
| 323 | clear_obf(kcs, status); |
| 324 | |
| 325 | if (GET_STATUS_ATN(status)) |
| 326 | return SI_SM_ATTN; |
| 327 | else |
| 328 | return SI_SM_IDLE; |
| 329 | |
| 330 | case KCS_START_OP: |
| 331 | if (state != KCS_IDLE) { |
| 332 | start_error_recovery(kcs, |
| 333 | "State machine not idle at start"); |
| 334 | break; |
| 335 | } |
| 336 | |
| 337 | clear_obf(kcs, status); |
| 338 | write_cmd(kcs, KCS_WRITE_START); |
| 339 | kcs->state = KCS_WAIT_WRITE_START; |
| 340 | break; |
| 341 | |
| 342 | case KCS_WAIT_WRITE_START: |
| 343 | if (state != KCS_WRITE_STATE) { |
| 344 | start_error_recovery( |
| 345 | kcs, |
| 346 | "Not in write state at write start"); |
| 347 | break; |
| 348 | } |
| 349 | read_data(kcs); |
| 350 | if (kcs->write_count == 1) { |
| 351 | write_cmd(kcs, KCS_WRITE_END); |
| 352 | kcs->state = KCS_WAIT_WRITE_END; |
| 353 | } else { |
| 354 | write_next_byte(kcs); |
| 355 | kcs->state = KCS_WAIT_WRITE; |
| 356 | } |
| 357 | break; |
| 358 | |
| 359 | case KCS_WAIT_WRITE: |
| 360 | if (state != KCS_WRITE_STATE) { |
| 361 | start_error_recovery(kcs, |
| 362 | "Not in write state for write"); |
| 363 | break; |
| 364 | } |
| 365 | clear_obf(kcs, status); |
| 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 | } |
| 372 | break; |
| 373 | |
| 374 | case KCS_WAIT_WRITE_END: |
| 375 | if (state != KCS_WRITE_STATE) { |
| 376 | start_error_recovery(kcs, |
| 377 | "Not in write state for write end"); |
| 378 | break; |
| 379 | } |
| 380 | clear_obf(kcs, status); |
| 381 | write_next_byte(kcs); |
| 382 | kcs->state = KCS_WAIT_READ; |
| 383 | break; |
| 384 | |
| 385 | case KCS_WAIT_READ: |
| 386 | if ((state != KCS_READ_STATE) && (state != KCS_IDLE_STATE)) { |
| 387 | start_error_recovery( |
| 388 | kcs, |
| 389 | "Not in read or idle in read state"); |
| 390 | break; |
| 391 | } |
| 392 | |
| 393 | if (state == KCS_READ_STATE) { |
| 394 | if (! check_obf(kcs, status, time)) |
| 395 | return SI_SM_CALL_WITH_DELAY; |
| 396 | read_next_byte(kcs); |
| 397 | } else { |
| 398 | /* We don't implement this exactly like the state |
| 399 | machine in the spec. Some broken hardware |
| 400 | does not write the final dummy byte to the |
| 401 | read register. Thus obf will never go high |
| 402 | here. We just go straight to idle, and we |
| 403 | handle clearing out obf in idle state if it |
| 404 | happens to come in. */ |
| 405 | clear_obf(kcs, status); |
| 406 | kcs->orig_write_count = 0; |
| 407 | kcs->state = KCS_IDLE; |
| 408 | return SI_SM_TRANSACTION_COMPLETE; |
| 409 | } |
| 410 | break; |
| 411 | |
| 412 | case KCS_ERROR0: |
| 413 | clear_obf(kcs, status); |
| 414 | write_cmd(kcs, KCS_GET_STATUS_ABORT); |
| 415 | kcs->state = KCS_ERROR1; |
| 416 | break; |
| 417 | |
| 418 | case KCS_ERROR1: |
| 419 | clear_obf(kcs, status); |
| 420 | write_data(kcs, 0); |
| 421 | kcs->state = KCS_ERROR2; |
| 422 | break; |
| 423 | |
| 424 | case KCS_ERROR2: |
| 425 | if (state != KCS_READ_STATE) { |
| 426 | start_error_recovery(kcs, |
| 427 | "Not in read state for error2"); |
| 428 | break; |
| 429 | } |
| 430 | if (! check_obf(kcs, status, time)) |
| 431 | return SI_SM_CALL_WITH_DELAY; |
| 432 | |
| 433 | clear_obf(kcs, status); |
| 434 | write_data(kcs, KCS_READ_BYTE); |
| 435 | kcs->state = KCS_ERROR3; |
| 436 | break; |
| 437 | |
| 438 | case KCS_ERROR3: |
| 439 | if (state != KCS_IDLE_STATE) { |
| 440 | start_error_recovery(kcs, |
| 441 | "Not in idle state for error3"); |
| 442 | break; |
| 443 | } |
| 444 | |
| 445 | if (! check_obf(kcs, status, time)) |
| 446 | return SI_SM_CALL_WITH_DELAY; |
| 447 | |
| 448 | clear_obf(kcs, status); |
| 449 | if (kcs->orig_write_count) { |
| 450 | restart_kcs_transaction(kcs); |
| 451 | } else { |
| 452 | kcs->state = KCS_IDLE; |
| 453 | return SI_SM_TRANSACTION_COMPLETE; |
| 454 | } |
| 455 | break; |
| 456 | |
| 457 | case KCS_HOSED: |
| 458 | break; |
| 459 | } |
| 460 | |
| 461 | if (kcs->state == KCS_HOSED) { |
| 462 | init_kcs_data(kcs, kcs->io); |
| 463 | return SI_SM_HOSED; |
| 464 | } |
| 465 | |
| 466 | return SI_SM_CALL_WITHOUT_DELAY; |
| 467 | } |
| 468 | |
| 469 | static int kcs_size(void) |
| 470 | { |
| 471 | return sizeof(struct si_sm_data); |
| 472 | } |
| 473 | |
| 474 | static int kcs_detect(struct si_sm_data *kcs) |
| 475 | { |
| 476 | /* It's impossible for the KCS status register to be all 1's, |
| 477 | (assuming a properly functioning, self-initialized BMC) |
| 478 | but that's what you get from reading a bogus address, so we |
| 479 | test that first. */ |
| 480 | if (read_status(kcs) == 0xff) |
| 481 | return 1; |
| 482 | |
| 483 | return 0; |
| 484 | } |
| 485 | |
| 486 | static void kcs_cleanup(struct si_sm_data *kcs) |
| 487 | { |
| 488 | } |
| 489 | |
| 490 | struct si_sm_handlers kcs_smi_handlers = |
| 491 | { |
| 492 | .version = IPMI_KCS_VERSION, |
| 493 | .init_data = init_kcs_data, |
| 494 | .start_transaction = start_kcs_transaction, |
| 495 | .get_result = get_kcs_result, |
| 496 | .event = kcs_event, |
| 497 | .detect = kcs_detect, |
| 498 | .cleanup = kcs_cleanup, |
| 499 | .size = kcs_size, |
| 500 | }; |