Skip to content
This repository
Fetching contributors…

Cannot retrieve contributors at this time

file 1471 lines (990 sloc) 32.927 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471
PARPORT interface documentation
-------------------------------

Time-stamp: <2000-02-24 13:30:20 twaugh>

Described here are the following functions:

Global functions:
  parport_register_driver
  parport_unregister_driver
  parport_enumerate
  parport_register_device
  parport_unregister_device
  parport_claim
  parport_claim_or_block
  parport_release
  parport_yield
  parport_yield_blocking
  parport_wait_peripheral
  parport_poll_peripheral
  parport_wait_event
  parport_negotiate
  parport_read
  parport_write
  parport_open
  parport_close
  parport_device_id
  parport_device_coords
  parport_find_class
  parport_find_device
  parport_set_timeout

Port functions (can be overridden by low-level drivers):
  SPP:
    port->ops->read_data
    port->ops->write_data
    port->ops->read_status
    port->ops->read_control
    port->ops->write_control
    port->ops->frob_control
    port->ops->enable_irq
    port->ops->disable_irq
    port->ops->data_forward
    port->ops->data_reverse

  EPP:
    port->ops->epp_write_data
    port->ops->epp_read_data
    port->ops->epp_write_addr
    port->ops->epp_read_addr

  ECP:
    port->ops->ecp_write_data
    port->ops->ecp_read_data
    port->ops->ecp_write_addr

  Other:
    port->ops->nibble_read_data
    port->ops->byte_read_data
    port->ops->compat_write_data

The parport subsystem comprises 'parport' (the core port-sharing
code), and a variety of low-level drivers that actually do the port
accesses. Each low-level driver handles a particular style of port
(PC, Amiga, and so on).

The parport interface to the device driver author can be broken down
into global functions and port functions.

The global functions are mostly for communicating between the device
driver and the parport subsystem: acquiring a list of available ports,
claiming a port for exclusive use, and so on. They also include
'generic' functions for doing standard things that will work on any
IEEE 1284-capable architecture.

The port functions are provided by the low-level drivers, although the
core parport module provides generic 'defaults' for some routines.
The port functions can be split into three groups: SPP, EPP, and ECP.

SPP (Standard Parallel Port) functions modify so-called 'SPP'
registers: data, status, and control. The hardware may not actually
have registers exactly like that, but the PC does and this interface is
modelled after common PC implementations. Other low-level drivers may
be able to emulate most of the functionality.

EPP (Enhanced Parallel Port) functions are provided for reading and
writing in IEEE 1284 EPP mode, and ECP (Extended Capabilities Port)
functions are used for IEEE 1284 ECP mode. (What about BECP? Does
anyone care?)

Hardware assistance for EPP and/or ECP transfers may or may not be
available, and if it is available it may or may not be used. If
hardware is not used, the transfer will be software-driven. In order
to cope with peripherals that only tenuously support IEEE 1284, a
low-level driver specific function is provided, for altering 'fudge
factors'.

GLOBAL FUNCTIONS
----------------

parport_register_driver - register a device driver with parport
-----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_driver {
const char *name;
void (*attach) (struct parport *);
void (*detach) (struct parport *);
struct parport_driver *next;
};
int parport_register_driver (struct parport_driver *driver);

DESCRIPTION

In order to be notified about parallel ports when they are detected,
parport_register_driver should be called. Your driver will
immediately be notified of all ports that have already been detected,
and of each new port as low-level drivers are loaded.

A 'struct parport_driver' contains the textual name of your driver,
a pointer to a function to handle new ports, and a pointer to a
function to handle ports going away due to a low-level driver
unloading. Ports will only be detached if they are not being used
(i.e. there are no devices registered on them).

The visible parts of the 'struct parport *' argument given to
attach/detach are:

struct parport
{
struct parport *next; /* next parport in list */
const char *name; /* port's name */
unsigned int modes; /* bitfield of hardware modes */
struct parport_device_info probe_info;
/* IEEE1284 info */
int number; /* parport index */
struct parport_operations *ops;
...
};

There are other members of the structure, but they should not be
touched.

The 'modes' member summarises the capabilities of the underlying
hardware. It consists of flags which may be bitwise-ored together:

  PARPORT_MODE_PCSPP IBM PC registers are available,
i.e. functions that act on data,
control and status registers are
probably writing directly to the
hardware.
  PARPORT_MODE_TRISTATE The data drivers may be turned off.
This allows the data lines to be used
for reverse (peripheral to host)
transfers.
  PARPORT_MODE_COMPAT The hardware can assist with
compatibility-mode (printer)
transfers, i.e. compat_write_block.
  PARPORT_MODE_EPP The hardware can assist with EPP
transfers.
  PARPORT_MODE_ECP The hardware can assist with ECP
transfers.
  PARPORT_MODE_DMA The hardware can use DMA, so you might
want to pass ISA DMA-able memory
(i.e. memory allocated using the
GFP_DMA flag with kmalloc) to the
low-level driver in order to take
advantage of it.

There may be other flags in 'modes' as well.

The contents of 'modes' is advisory only. For example, if the
hardware is capable of DMA, and PARPORT_MODE_DMA is in 'modes', it
doesn't necessarily mean that DMA will always be used when possible.
Similarly, hardware that is capable of assisting ECP transfers won't
necessarily be used.

RETURN VALUE

Zero on success, otherwise an error code.

ERRORS

None. (Can it fail? Why return int?)

EXAMPLE

static void lp_attach (struct parport *port)
{
...
private = kmalloc (...);
dev[count++] = parport_register_device (...);
...
}

static void lp_detach (struct parport *port)
{
...
}

static struct parport_driver lp_driver = {
"lp",
lp_attach,
lp_detach,
NULL /* always put NULL here */
};

int lp_init (void)
{
...
if (parport_register_driver (&lp_driver)) {
/* Failed; nothing we can do. */
return -EIO;
}
...
}

SEE ALSO

parport_unregister_driver, parport_register_device, parport_enumerate

parport_unregister_driver - tell parport to forget about this driver
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_driver {
const char *name;
void (*attach) (struct parport *);
void (*detach) (struct parport *);
struct parport_driver *next;
};
void parport_unregister_driver (struct parport_driver *driver);

DESCRIPTION

This tells parport not to notify the device driver of new ports or of
ports going away. Registered devices belonging to that driver are NOT
unregistered: parport_unregister_device must be used for each one.

EXAMPLE

void cleanup_module (void)
{
...
/* Stop notifications. */
parport_unregister_driver (&lp_driver);

/* Unregister devices. */
for (i = 0; i < NUM_DEVS; i++)
parport_unregister_device (dev[i]);
...
}

SEE ALSO

parport_register_driver, parport_enumerate

parport_enumerate - retrieve a list of parallel ports (DEPRECATED)
-----------------

SYNOPSIS

#include <linux/parport.h>

struct parport *parport_enumerate (void);

DESCRIPTION

Retrieve the first of a list of valid parallel ports for this machine.
Successive parallel ports can be found using the 'struct parport
*next' element of the 'struct parport *' that is returned. If 'next'
is NULL, there are no more parallel ports in the list. The number of
ports in the list will not exceed PARPORT_MAX.

RETURN VALUE

A 'struct parport *' describing a valid parallel port for the machine,
or NULL if there are none.

ERRORS

This function can return NULL to indicate that there are no parallel
ports to use.

EXAMPLE

int detect_device (void)
{
struct parport *port;

for (port = parport_enumerate ();
port != NULL;
port = port->next) {
/* Try to detect a device on the port... */
...
             }
}

...
}

NOTES

parport_enumerate is deprecated; parport_register_driver should be
used instead.

SEE ALSO

parport_register_driver, parport_unregister_driver

parport_register_device - register to use a port
-----------------------

SYNOPSIS

#include <linux/parport.h>

typedef int (*preempt_func) (void *handle);
typedef void (*wakeup_func) (void *handle);
typedef int (*irq_func) (int irq, void *handle, struct pt_regs *);

struct pardevice *parport_register_device(struct parport *port,
                                          const char *name,
                                          preempt_func preempt,
                                          wakeup_func wakeup,
                                          irq_func irq,
                                          int flags,
                                          void *handle);

DESCRIPTION

Use this function to register your device driver on a parallel port
('port'). Once you have done that, you will be able to use
parport_claim and parport_release in order to use the port.

The ('name') argument is the name of the device that appears in /proc
filesystem. The string must be valid for the whole lifetime of the
device (until parport_unregister_device is called).

This function will register three callbacks into your driver:
'preempt', 'wakeup' and 'irq'. Each of these may be NULL in order to
indicate that you do not want a callback.

When the 'preempt' function is called, it is because another driver
wishes to use the parallel port. The 'preempt' function should return
non-zero if the parallel port cannot be released yet -- if zero is
returned, the port is lost to another driver and the port must be
re-claimed before use.

The 'wakeup' function is called once another driver has released the
port and no other driver has yet claimed it. You can claim the
parallel port from within the 'wakeup' function (in which case the
claim is guaranteed to succeed), or choose not to if you don't need it
now.

If an interrupt occurs on the parallel port your driver has claimed,
the 'irq' function will be called. (Write something about shared
interrupts here.)

The 'handle' is a pointer to driver-specific data, and is passed to
the callback functions.

'flags' may be a bitwise combination of the following flags:

        Flag Meaning
  PARPORT_DEV_EXCL The device cannot share the parallel port at all.
Use this only when absolutely necessary.

The typedefs are not actually defined -- they are only shown in order
to make the function prototype more readable.

The visible parts of the returned 'struct pardevice' are:

struct pardevice {
struct parport *port; /* Associated port */
void *private; /* Device driver's 'handle' */
...
};

RETURN VALUE

A 'struct pardevice *': a handle to the registered parallel port
device that can be used for parport_claim, parport_release, etc.

ERRORS

A return value of NULL indicates that there was a problem registering
a device on that port.

EXAMPLE

static int preempt (void *handle)
{
if (busy_right_now)
return 1;

must_reclaim_port = 1;
return 0;
}

static void wakeup (void *handle)
{
struct toaster *private = handle;
struct pardevice *dev = private->dev;
if (!dev) return; /* avoid races */

if (want_port)
parport_claim (dev);
}

static int toaster_detect (struct toaster *private, struct parport *port)
{
private->dev = parport_register_device (port, "toaster", preempt,
wakeup, NULL, 0,
private);
if (!private->dev)
/* Couldn't register with parport. */
return -EIO;

must_reclaim_port = 0;
busy_right_now = 1;
parport_claim_or_block (private->dev);
...
/* Don't need the port while the toaster warms up. */
busy_right_now = 0;
...
busy_right_now = 1;
if (must_reclaim_port) {
parport_claim_or_block (private->dev);
must_reclaim_port = 0;
}
...
}

SEE ALSO

parport_unregister_device, parport_claim

parport_unregister_device - finish using a port
-------------------------

SYNPOPSIS

#include <linux/parport.h>

void parport_unregister_device (struct pardevice *dev);

DESCRIPTION

This function is the opposite of parport_register_device. After using
parport_unregister_device, 'dev' is no longer a valid device handle.

You should not unregister a device that is currently claimed, although
if you do it will be released automatically.

EXAMPLE

...
kfree (dev->private); /* before we lose the pointer */
parport_unregister_device (dev);
...

SEE ALSO

parport_unregister_driver

parport_claim, parport_claim_or_block - claim the parallel port for a device
-------------------------------------

SYNOPSIS

#include <linux/parport.h>

int parport_claim (struct pardevice *dev);
int parport_claim_or_block (struct pardevice *dev);

DESCRIPTION

These functions attempt to gain control of the parallel port on which
'dev' is registered. 'parport_claim' does not block, but
'parport_claim_or_block' may do. (Put something here about blocking
interruptibly or non-interruptibly.)

You should not try to claim a port that you have already claimed.

RETURN VALUE

A return value of zero indicates that the port was successfully
claimed, and the caller now has possession of the parallel port.

If 'parport_claim_or_block' blocks before returning successfully, the
return value is positive.

ERRORS

  -EAGAIN The port is unavailable at the moment, but another attempt
           to claim it may succeed.

SEE ALSO

parport_release

parport_release - release the parallel port
---------------

SYNOPSIS

#include <linux/parport.h>

void parport_release (struct pardevice *dev);

DESCRIPTION

Once a parallel port device has been claimed, it can be released using
'parport_release'. It cannot fail, but you should not release a
device that you do not have possession of.

EXAMPLE

static size_t write (struct pardevice *dev, const void *buf,
size_t len)
{
...
written = dev->port->ops->write_ecp_data (dev->port, buf,
len);
parport_release (dev);
...
}


SEE ALSO

change_mode, parport_claim, parport_claim_or_block, parport_yield

parport_yield, parport_yield_blocking - temporarily release a parallel port
-------------------------------------

SYNOPSIS

#include <linux/parport.h>

int parport_yield (struct pardevice *dev)
int parport_yield_blocking (struct pardevice *dev);

DESCRIPTION

When a driver has control of a parallel port, it may allow another
driver to temporarily 'borrow' it. 'parport_yield' does not block;
'parport_yield_blocking' may do.

RETURN VALUE

A return value of zero indicates that the caller still owns the port
and the call did not block.

A positive return value from 'parport_yield_blocking' indicates that
the caller still owns the port and the call blocked.

A return value of -EAGAIN indicates that the caller no longer owns the
port, and it must be re-claimed before use.

ERRORS

  -EAGAIN Ownership of the parallel port was given away.

SEE ALSO

parport_release

parport_wait_peripheral - wait for status lines, up to 35ms
-----------------------

SYNOPSIS

#include <linux/parport.h>

int parport_wait_peripheral (struct parport *port,
unsigned char mask,
unsigned char val);

DESCRIPTION

Wait for the status lines in mask to match the values in val.

RETURN VALUE

 -EINTR a signal is pending
      0 the status lines in mask have values in val
      1 timed out while waiting (35ms elapsed)

SEE ALSO

parport_poll_peripheral

parport_poll_peripheral - wait for status lines, in usec
-----------------------

SYNOPSIS

#include <linux/parport.h>

int parport_poll_peripheral (struct parport *port,
unsigned char mask,
unsigned char val,
int usec);

DESCRIPTION

Wait for the status lines in mask to match the values in val.

RETURN VALUE

 -EINTR a signal is pending
      0 the status lines in mask have values in val
      1 timed out while waiting (usec microseconds have elapsed)

SEE ALSO

parport_wait_peripheral

parport_wait_event - wait for an event on a port
------------------

SYNOPSIS

#include <linux/parport.h>

int parport_wait_event (struct parport *port, signed long timeout)

DESCRIPTION

Wait for an event (e.g. interrupt) on a port. The timeout is in
jiffies.

RETURN VALUE

      0 success
     <0 error (exit as soon as possible)
     >0 timed out

parport_negotiate - perform IEEE 1284 negotiation
-----------------

SYNOPSIS

#include <linux/parport.h>

int parport_negotiate (struct parport *, int mode);

DESCRIPTION

Perform IEEE 1284 negotiation.

RETURN VALUE

     0 handshake OK; IEEE 1284 peripheral and mode available
    -1 handshake failed; peripheral not compliant (or none present)
     1 handshake OK; IEEE 1284 peripheral present but mode not
        available

SEE ALSO

parport_read, parport_write

parport_read - read data from device
------------

SYNOPSIS

#include <linux/parport.h>

ssize_t parport_read (struct parport *, void *buf, size_t len);

DESCRIPTION

Read data from device in current IEEE 1284 transfer mode. This only
works for modes that support reverse data transfer.

RETURN VALUE

If negative, an error code; otherwise the number of bytes transferred.

SEE ALSO

parport_write, parport_negotiate

parport_write - write data to device
-------------

SYNOPSIS

#include <linux/parport.h>

ssize_t parport_write (struct parport *, const void *buf, size_t len);

DESCRIPTION

Write data to device in current IEEE 1284 transfer mode. This only
works for modes that support forward data transfer.

RETURN VALUE

If negative, an error code; otherwise the number of bytes transferred.

SEE ALSO

parport_read, parport_negotiate

parport_open - register device for particular device number
------------

SYNOPSIS

#include <linux/parport.h>

struct pardevice *parport_open (int devnum, const char *name,
int (*pf) (void *),
void (*kf) (void *),
void (*irqf) (int, void *,
struct pt_regs *),
int flags, void *handle);

DESCRIPTION

This is like parport_register_device but takes a device number instead
of a pointer to a struct parport.

RETURN VALUE

See parport_register_device. If no device is associated with devnum,
NULL is returned.

SEE ALSO

parport_register_device

parport_close - unregister device for particular device number
-------------

SYNOPSIS

#include <linux/parport.h>

void parport_close (struct pardevice *dev);

DESCRIPTION

This is the equivalent of parport_unregister_device for parport_open.

SEE ALSO

parport_unregister_device, parport_open

parport_device_id - obtain IEEE 1284 Device ID
-----------------

SYNOPSIS

#include <linux/parport.h>

ssize_t parport_device_id (int devnum, char *buffer, size_t len);

DESCRIPTION

Obtains the IEEE 1284 Device ID associated with a given device.

RETURN VALUE

If negative, an error code; otherwise, the number of bytes of buffer
that contain the device ID. The format of the device ID is as
follows:

[length][ID]

The first two bytes indicate the inclusive length of the entire Device
ID, and are in big-endian order. The ID is a sequence of pairs of the
form:

key:value;

NOTES

Many devices have ill-formed IEEE 1284 Device IDs.

SEE ALSO

parport_find_class, parport_find_device

parport_device_coords - convert device number to device coordinates
------------------

SYNOPSIS

#include <linux/parport.h>

int parport_device_coords (int devnum, int *parport, int *mux,
int *daisy);

DESCRIPTION

Convert between device number (zero-based) and device coordinates
(port, multiplexor, daisy chain address).

RETURN VALUE

Zero on success, in which case the coordinates are (*parport, *mux,
*daisy).

SEE ALSO

parport_open, parport_device_id

parport_find_class - find a device by its class
------------------

SYNOPSIS

#include <linux/parport.h>

typedef enum {
PARPORT_CLASS_LEGACY = 0, /* Non-IEEE1284 device */
PARPORT_CLASS_PRINTER,
PARPORT_CLASS_MODEM,
PARPORT_CLASS_NET,
PARPORT_CLASS_HDC, /* Hard disk controller */
PARPORT_CLASS_PCMCIA,
PARPORT_CLASS_MEDIA, /* Multimedia device */
PARPORT_CLASS_FDC, /* Floppy disk controller */
PARPORT_CLASS_PORTS,
PARPORT_CLASS_SCANNER,
PARPORT_CLASS_DIGCAM,
PARPORT_CLASS_OTHER, /* Anything else */
PARPORT_CLASS_UNSPEC, /* No CLS field in ID */
PARPORT_CLASS_SCSIADAPTER
} parport_device_class;

int parport_find_class (parport_device_class cls, int from);

DESCRIPTION

Find a device by class. The search starts from device number from+1.

RETURN VALUE

The device number of the next device in that class, or -1 if no such
device exists.

NOTES

Example usage:

int devnum = -1;
while ((devnum = parport_find_class (PARPORT_CLASS_DIGCAM, devnum)) != -1) {
    struct pardevice *dev = parport_open (devnum, ...);
    ...
}

SEE ALSO

parport_find_device, parport_open, parport_device_id

parport_find_device - find a device by its class
------------------

SYNOPSIS

#include <linux/parport.h>

int parport_find_device (const char *mfg, const char *mdl, int from);

DESCRIPTION

Find a device by vendor and model. The search starts from device
number from+1.

RETURN VALUE

The device number of the next device matching the specifications, or
-1 if no such device exists.

NOTES

Example usage:

int devnum = -1;
while ((devnum = parport_find_device ("IOMEGA", "ZIP+", devnum)) != -1) {
    struct pardevice *dev = parport_open (devnum, ...);
    ...
}

SEE ALSO

parport_find_class, parport_open, parport_device_id

parport_set_timeout - set the inactivity timeout
-------------------

SYNOPSIS

#include <linux/parport.h>

long parport_set_timeout (struct pardevice *dev, long inactivity);

DESCRIPTION

Set the inactivity timeout, in jiffies, for a registered device. The
previous timeout is returned.

RETURN VALUE

The previous timeout, in jiffies.

NOTES

Some of the port->ops functions for a parport may take time, owing to
delays at the peripheral. After the peripheral has not responded for
'inactivity' jiffies, a timeout will occur and the blocking function
will return.

A timeout of 0 jiffies is a special case: the function must do as much
as it can without blocking or leaving the hardware in an unknown
state. If port operations are performed from within an interrupt
handler, for instance, a timeout of 0 jiffies should be used.

Once set for a registered device, the timeout will remain at the set
value until set again.

SEE ALSO

port->ops->xxx_read/write_yyy

PORT FUNCTIONS
--------------

The functions in the port->ops structure (struct parport_operations)
are provided by the low-level driver responsible for that port.

port->ops->read_data - read the data register
--------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
unsigned char (*read_data) (struct parport *port);
...
};

DESCRIPTION

If port->modes contains the PARPORT_MODE_TRISTATE flag and the
PARPORT_CONTROL_DIRECTION bit in the control register is set, this
returns the value on the data pins. If port->modes contains the
PARPORT_MODE_TRISTATE flag and the PARPORT_CONTROL_DIRECTION bit is
not set, the return value _may_ be the last value written to the data
register. Otherwise the return value is undefined.

SEE ALSO

write_data, read_status, write_control

port->ops->write_data - write the data register
---------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
void (*write_data) (struct parport *port, unsigned char d);
...
};

DESCRIPTION

Writes to the data register. May have side-effects (a STROBE pulse,
for instance).

SEE ALSO

read_data, read_status, write_control

port->ops->read_status - read the status register
----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
unsigned char (*read_status) (struct parport *port);
...
};

DESCRIPTION

Reads from the status register. This is a bitmask:

- PARPORT_STATUS_ERROR (printer fault, "nFault")
- PARPORT_STATUS_SELECT (on-line, "Select")
- PARPORT_STATUS_PAPEROUT (no paper, "PError")
- PARPORT_STATUS_ACK (handshake, "nAck")
- PARPORT_STATUS_BUSY (busy, "Busy")

There may be other bits set.

SEE ALSO

read_data, write_data, write_control

port->ops->read_control - read the control register
-----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
unsigned char (*read_control) (struct parport *port);
...
};

DESCRIPTION

Returns the last value written to the control register (either from
write_control or frob_control). No port access is performed.

SEE ALSO

read_data, write_data, read_status, write_control

port->ops->write_control - write the control register
------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
void (*write_control) (struct parport *port, unsigned char s);
...
};

DESCRIPTION

Writes to the control register. This is a bitmask:
                          _______
- PARPORT_CONTROL_STROBE (nStrobe)
                          _______
- PARPORT_CONTROL_AUTOFD (nAutoFd)
                        _____
- PARPORT_CONTROL_INIT (nInit)
                          _________
- PARPORT_CONTROL_SELECT (nSelectIn)

SEE ALSO

read_data, write_data, read_status, frob_control

port->ops->frob_control - write control register bits
-----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
unsigned char (*frob_control) (struct parport *port,
unsigned char mask,
unsigned char val);
...
};

DESCRIPTION

This is equivalent to reading from the control register, masking out
the bits in mask, exclusive-or'ing with the bits in val, and writing
the result to the control register.

As some ports don't allow reads from the control port, a software copy
of its contents is maintained, so frob_control is in fact only one
port access.

SEE ALSO

read_data, write_data, read_status, write_control

port->ops->enable_irq - enable interrupt generation
---------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
void (*enable_irq) (struct parport *port);
...
};

DESCRIPTION

The parallel port hardware is instructed to generate interrupts at
appropriate moments, although those moments are
architecture-specific. For the PC architecture, interrupts are
commonly generated on the rising edge of nAck.

SEE ALSO

disable_irq

port->ops->disable_irq - disable interrupt generation
----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
void (*disable_irq) (struct parport *port);
...
};

DESCRIPTION

The parallel port hardware is instructed not to generate interrupts.
The interrupt itself is not masked.

SEE ALSO

enable_irq

port->ops->data_forward - enable data drivers
-----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
void (*data_forward) (struct parport *port);
...
};

DESCRIPTION

Enables the data line drivers, for 8-bit host-to-peripheral
communications.

SEE ALSO

data_reverse

port->ops->data_reverse - tristate the buffer
-----------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
void (*data_reverse) (struct parport *port);
...
};

DESCRIPTION

Places the data bus in a high impedance state, if port->modes has the
PARPORT_MODE_TRISTATE bit set.

SEE ALSO

data_forward

port->ops->epp_write_data - write EPP data
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
size_t (*epp_write_data) (struct parport *port, const void *buf,
size_t len, int flags);
...
};

DESCRIPTION

Writes data in EPP mode, and returns the number of bytes written.

The 'flags' parameter may be one or more of the following,
bitwise-or'ed together:

PARPORT_EPP_FAST Use fast transfers. Some chips provide 16-bit and
32-bit registers. However, if a transfer
times out, the return value may be unreliable.

SEE ALSO

epp_read_data, epp_write_addr, epp_read_addr

port->ops->epp_read_data - read EPP data
------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
size_t (*epp_read_data) (struct parport *port, void *buf,
size_t len, int flags);
...
};

DESCRIPTION

Reads data in EPP mode, and returns the number of bytes read.

The 'flags' parameter may be one or more of the following,
bitwise-or'ed together:

PARPORT_EPP_FAST Use fast transfers. Some chips provide 16-bit and
32-bit registers. However, if a transfer
times out, the return value may be unreliable.

SEE ALSO

epp_write_data, epp_write_addr, epp_read_addr

port->ops->epp_write_addr - write EPP address
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
size_t (*epp_write_addr) (struct parport *port,
const void *buf, size_t len, int flags);
...
};

DESCRIPTION

Writes EPP addresses (8 bits each), and returns the number written.

The 'flags' parameter may be one or more of the following,
bitwise-or'ed together:

PARPORT_EPP_FAST Use fast transfers. Some chips provide 16-bit and
32-bit registers. However, if a transfer
times out, the return value may be unreliable.

(Does PARPORT_EPP_FAST make sense for this function?)

SEE ALSO

epp_write_data, epp_read_data, epp_read_addr

port->ops->epp_read_addr - read EPP address
------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
size_t (*epp_read_addr) (struct parport *port, void *buf,
size_t len, int flags);
...
};

DESCRIPTION

Reads EPP addresses (8 bits each), and returns the number read.

The 'flags' parameter may be one or more of the following,
bitwise-or'ed together:

PARPORT_EPP_FAST Use fast transfers. Some chips provide 16-bit and
32-bit registers. However, if a transfer
times out, the return value may be unreliable.

(Does PARPORT_EPP_FAST make sense for this function?)

SEE ALSO

epp_write_data, epp_read_data, epp_write_addr

port->ops->ecp_write_data - write a block of ECP data
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
size_t (*ecp_write_data) (struct parport *port,
const void *buf, size_t len, int flags);
...
};

DESCRIPTION

Writes a block of ECP data. The 'flags' parameter is ignored.

RETURN VALUE

The number of bytes written.

SEE ALSO

ecp_read_data, ecp_write_addr

port->ops->ecp_read_data - read a block of ECP data
------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
size_t (*ecp_read_data) (struct parport *port,
void *buf, size_t len, int flags);
...
};

DESCRIPTION

Reads a block of ECP data. The 'flags' parameter is ignored.

RETURN VALUE

The number of bytes read. NB. There may be more unread data in a
FIFO. Is there a way of stunning the FIFO to prevent this?

SEE ALSO

ecp_write_block, ecp_write_addr

port->ops->ecp_write_addr - write a block of ECP addresses
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
size_t (*ecp_write_addr) (struct parport *port,
const void *buf, size_t len, int flags);
...
};

DESCRIPTION

Writes a block of ECP addresses. The 'flags' parameter is ignored.

RETURN VALUE

The number of bytes written.

NOTES

This may use a FIFO, and if so shall not return until the FIFO is empty.

SEE ALSO

ecp_read_data, ecp_write_data

port->ops->nibble_read_data - read a block of data in nibble mode
---------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
size_t (*nibble_read_data) (struct parport *port,
void *buf, size_t len, int flags);
...
};

DESCRIPTION

Reads a block of data in nibble mode. The 'flags' parameter is ignored.

RETURN VALUE

The number of whole bytes read.

SEE ALSO

byte_read_data, compat_write_data

port->ops->byte_read_data - read a block of data in byte mode
-------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
size_t (*byte_read_data) (struct parport *port,
void *buf, size_t len, int flags);
...
};

DESCRIPTION

Reads a block of data in byte mode. The 'flags' parameter is ignored.

RETURN VALUE

The number of bytes read.

SEE ALSO

nibble_read_data, compat_write_data

port->ops->compat_write_data - write a block of data in compatibility mode
----------------------------

SYNOPSIS

#include <linux/parport.h>

struct parport_operations {
...
size_t (*compat_write_data) (struct parport *port,
const void *buf, size_t len, int flags);
...
};

DESCRIPTION

Writes a block of data in compatibility mode. The 'flags' parameter
is ignored.

RETURN VALUE

The number of bytes written.

SEE ALSO

nibble_read_data, byte_read_data
Something went wrong with that request. Please try again.