aboutsummaryrefslogtreecommitdiffstats
path: root/include/linux/i2c-pxa.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/linux/i2c-pxa.h')
0 files changed, 0 insertions, 0 deletions
generated by cgit v1.2.2 (git 2.25.0) at 2025-10-01 20:35:38 -0400
5' href='#n55'>55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 

                          The Linux IPMI Driver
			  ---------------------
			      Corey Minyard
			  <minyard@mvista.com>
			    <minyard@acm.org>

The Intelligent Platform Management Interface, or IPMI, is a
standard for controlling intelligent devices that monitor a system.
It provides for dynamic discovery of sensors in the system and the
ability to monitor the sensors and be informed when the sensor's
values change or go outside certain boundaries.  It also has a
standardized database for field-replaceable units (FRUs) and a watchdog
timer.

To use this, you need an interface to an IPMI controller in your
system (called a Baseboard Management Controller, or BMC) and
management software that can use the IPMI system.

This document describes how to use the IPMI driver for Linux.  If you
are not familiar with IPMI itself, see the web site at
http://www.intel.com/design/servers/ipmi/index.htm.  IPMI is a big
subject and I can't cover it all here!

Configuration
-------------

The Linux IPMI driver is modular, which means you have to pick several
things to have it work right depending on your hardware.  Most of
these are available in the 'Character Devices' menu then the IPMI
menu.

No matter what, you must pick 'IPMI top-level message handler' to use
IPMI.  What you do beyond that depends on your needs and hardware.

The message handler does not provide any user-level interfaces.
Kernel code (like the watchdog) can still use it.  If you need access
from userland, you need to select 'Device interface for IPMI' if you
want access through a device driver.

The driver interface depends on your hardware.  If your system
properly provides the SMBIOS info for IPMI, the driver will detect it
and just work.  If you have a board with a standard interface (These
will generally be either "KCS", "SMIC", or "BT", consult your hardware
manual), choose the 'IPMI SI handler' option.  A driver also exists
for direct I2C access to the IPMI management controller.  Some boards
support this, but it is unknown if it will work on every board.  For
this, choose 'IPMI SMBus handler', but be ready to try to do some
figuring to see if it will work on your system if the SMBIOS/APCI
information is wrong or not present.  It is fairly safe to have both
these enabled and let the drivers auto-detect what is present.

You should generally enable ACPI on your system, as systems with IPMI
can have ACPI tables describing them.

If you have a standard interface and the board manufacturer has done
their job correctly, the IPMI controller should be automatically
detected (via ACPI or SMBIOS tables) and should just work.  Sadly,
many boards do not have this information.  The driver attempts
standard defaults, but they may not work.  If you fall into this
situation, you need to read the section below named 'The SI Driver' or
"The SMBus Driver" on how to hand-configure your system.

IPMI defines a standard watchdog timer.  You can enable this with the
'IPMI Watchdog Timer' config option.  If you compile the driver into
the kernel, then via a kernel command-line option you can have the
watchdog timer start as soon as it initializes.  It also have a lot
of other options, see the 'Watchdog' section below for more details.
Note that you can also have the watchdog continue to run if it is
closed (by default it is disabled on close).  Go into the 'Watchdog
Cards' menu, enable 'Watchdog Timer Support', and enable the option
'Disable watchdog shutdown on close'.

IPMI systems can often be powered off using IPMI commands.  Select
'IPMI Poweroff' to do this.  The driver will auto-detect if the system
can be powered off by IPMI.  It is safe to enable this even if your
system doesn't support this option.  This works on ATCA systems, the
Radisys CPI1 card, and any IPMI system that supports standard chassis
management commands.

If you want the driver to put an event into the event log on a panic,
enable the 'Generate a panic event to all BMCs on a panic' option.  If
you want the whole panic string put into the event log using OEM
events, enable the 'Generate OEM events containing the panic string'
option.

Basic Design
------------

The Linux IPMI driver is designed to be very modular and flexible, you
only need to take the pieces you need and you can use it in many
different ways.  Because of that, it's broken into many chunks of
code.  These chunks (by module name) are:

ipmi_msghandler - This is the central piece of software for the IPMI
system.  It handles all messages, message timing, and responses.  The
IPMI users tie into this, and the IPMI physical interfaces (called
System Management Interfaces, or SMIs) also tie in here.  This
provides the kernelland interface for IPMI, but does not provide an
interface for use by application processes.

ipmi_devintf - This provides a userland IOCTL interface for the IPMI
driver, each open file for this device ties in to the message handler
as an IPMI user.

ipmi_si - A driver for various system interfaces.  This supports KCS,
SMIC, and BT interfaces.  Unless you have an SMBus interface or your
own custom interface, you probably need to use this.

ipmi_smb - A driver for accessing BMCs on the SMBus. It uses the
I2C kernel driver's SMBus interfaces to send and receive IPMI messages
over the SMBus.

ipmi_watchdog - IPMI requires systems to have a very capable watchdog
timer.  This driver implements the standard Linux watchdog timer
interface on top of the IPMI message handler.

ipmi_poweroff - Some systems support the ability to be turned off via
IPMI commands.

These are all individually selectable via configuration options.

Note that the KCS-only interface has been removed.  The af_ipmi driver
is no longer supported and has been removed because it was impossible
to do 32 bit emulation on 64-bit kernels with it.

Much documentation for the interface is in the include files.  The
IPMI include files are:

net/af_ipmi.h - Contains the socket interface.

linux/ipmi.h - Contains the user interface and IOCTL interface for IPMI.

linux/ipmi_smi.h - Contains the interface for system management interfaces
(things that interface to IPMI controllers) to use.

linux/ipmi_msgdefs.h - General definitions for base IPMI messaging.


Addressing
----------

The IPMI addressing works much like IP addresses, you have an overlay
to handle the different address types.  The overlay is: