ide-tape.c 55.2 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 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072
/*
 * IDE ATAPI streaming tape driver.
 *
 * Copyright (C) 1995-1999  Gadi Oxman <gadio@netvision.net.il>
 * Copyright (C) 2003-2005  Bartlomiej Zolnierkiewicz
 *
 * This driver was constructed as a student project in the software laboratory
 * of the faculty of electrical engineering in the Technion - Israel's
 * Institute Of Technology, with the guide of Avner Lottem and Dr. Ilana David.
 *
 * It is hereby placed under the terms of the GNU general public license.
 * (See linux/COPYING).
 *
 * For a historical changelog see
 * Documentation/ide/ChangeLog.ide-tape.1995-2002
 */

#define DRV_NAME "ide-tape"

#define IDETAPE_VERSION "1.20"

#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/genhd.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/ide.h>
#include <linux/completion.h>
#include <linux/bitops.h>
#include <linux/mutex.h>
#include <scsi/scsi.h>

#include <asm/byteorder.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <asm/unaligned.h>
#include <linux/mtio.h>

/* define to see debug info */
#undef IDETAPE_DEBUG_LOG

#ifdef IDETAPE_DEBUG_LOG
#define ide_debug_log(lvl, fmt, args...) __ide_debug_log(lvl, fmt, ## args)
#else
#define ide_debug_log(lvl, fmt, args...) do {} while (0)
#endif

/**************************** Tunable parameters *****************************/
/*
 * After each failed packet command we issue a request sense command and retry
 * the packet command IDETAPE_MAX_PC_RETRIES times.
 *
 * Setting IDETAPE_MAX_PC_RETRIES to 0 will disable retries.
 */
#define IDETAPE_MAX_PC_RETRIES		3

/*
 * The following parameter is used to select the point in the internal tape fifo
 * in which we will start to refill the buffer. Decreasing the following
 * parameter will improve the system's latency and interactive response, while
 * using a high value might improve system throughput.
 */
#define IDETAPE_FIFO_THRESHOLD		2

/*
 * DSC polling parameters.
 *
 * Polling for DSC (a single bit in the status register) is a very important
 * function in ide-tape. There are two cases in which we poll for DSC:
 *
 * 1. Before a read/write packet command, to ensure that we can transfer data
 * from/to the tape's data buffers, without causing an actual media access.
 * In case the tape is not ready yet, we take out our request from the device
 * request queue, so that ide.c could service requests from the other device
 * on the same interface in the meantime.
 *
 * 2. After the successful initialization of a "media access packet command",
 * which is a command that can take a long time to complete (the interval can
 * range from several seconds to even an hour). Again, we postpone our request
 * in the middle to free the bus for the other device. The polling frequency
 * here should be lower than the read/write frequency since those media access
 * commands are slow. We start from a "fast" frequency - IDETAPE_DSC_MA_FAST
 * (1 second), and if we don't receive DSC after IDETAPE_DSC_MA_THRESHOLD
 * (5 min), we switch it to a lower frequency - IDETAPE_DSC_MA_SLOW (1 min).
 *
 * We also set a timeout for the timer, in case something goes wrong. The
 * timeout should be longer then the maximum execution time of a tape operation.
 */

/* DSC timings. */
#define IDETAPE_DSC_RW_MIN		5*HZ/100	/* 50 msec */
#define IDETAPE_DSC_RW_MAX		40*HZ/100	/* 400 msec */
#define IDETAPE_DSC_RW_TIMEOUT		2*60*HZ		/* 2 minutes */
#define IDETAPE_DSC_MA_FAST		2*HZ		/* 2 seconds */
#define IDETAPE_DSC_MA_THRESHOLD	5*60*HZ		/* 5 minutes */
#define IDETAPE_DSC_MA_SLOW		30*HZ		/* 30 seconds */
#define IDETAPE_DSC_MA_TIMEOUT		2*60*60*HZ	/* 2 hours */

/*************************** End of tunable parameters ***********************/

/* tape directions */
enum {
	IDETAPE_DIR_NONE  = (1 << 0),
	IDETAPE_DIR_READ  = (1 << 1),
	IDETAPE_DIR_WRITE = (1 << 2),
};

/* Tape door status */
#define DOOR_UNLOCKED			0
#define DOOR_LOCKED			1
#define DOOR_EXPLICITLY_LOCKED		2

/* Some defines for the SPACE command */
#define IDETAPE_SPACE_OVER_FILEMARK	1
#define IDETAPE_SPACE_TO_EOD		3

/* Some defines for the LOAD UNLOAD command */
#define IDETAPE_LU_LOAD_MASK		1
#define IDETAPE_LU_RETENSION_MASK	2
#define IDETAPE_LU_EOT_MASK		4

/* Structures related to the SELECT SENSE / MODE SENSE packet commands. */
#define IDETAPE_BLOCK_DESCRIPTOR	0
#define IDETAPE_CAPABILITIES_PAGE	0x2a

/*
 * Most of our global data which we need to save even as we leave the driver due
 * to an interrupt or a timer event is stored in the struct defined below.
 */
typedef struct ide_tape_obj {
	ide_drive_t		*drive;
	struct ide_driver	*driver;
	struct gendisk		*disk;
	struct device		dev;

	/* used by REQ_IDETAPE_{READ,WRITE} requests */
	struct ide_atapi_pc queued_pc;

	/*
	 * DSC polling variables.
	 *
	 * While polling for DSC we use postponed_rq to postpone the current
	 * request so that ide.c will be able to service pending requests on the
	 * other device. Note that at most we will have only one DSC (usually
	 * data transfer) request in the device request queue.
	 */
	bool postponed_rq;

	/* The time in which we started polling for DSC */
	unsigned long dsc_polling_start;
	/* Timer used to poll for dsc */
	struct timer_list dsc_timer;
	/* Read/Write dsc polling frequency */
	unsigned long best_dsc_rw_freq;
	unsigned long dsc_poll_freq;
	unsigned long dsc_timeout;

	/* Read position information */
	u8 partition;
	/* Current block */
	unsigned int first_frame;

	/* Last error information */
	u8 sense_key, asc, ascq;

	/* Character device operation */
	unsigned int minor;
	/* device name */
	char name[4];
	/* Current character device data transfer direction */
	u8 chrdev_dir;

	/* tape block size, usually 512 or 1024 bytes */
	unsigned short blk_size;
	int user_bs_factor;

	/* Copy of the tape's Capabilities and Mechanical Page */
	u8 caps[20];

	/*
	 * Active data transfer request parameters.
	 *
	 * At most, there is only one ide-tape originated data transfer request
	 * in the device request queue. This allows ide.c to easily service
	 * requests from the other device when we postpone our active request.
	 */

	/* Data buffer size chosen based on the tape's recommendation */
	int buffer_size;
	/* Staging buffer of buffer_size bytes */
	void *buf;
	/* The read/write cursor */
	void *cur;
	/* The number of valid bytes in buf */
	size_t valid;

	/* Measures average tape speed */
	unsigned long avg_time;
	int avg_size;
	int avg_speed;

	/* the door is currently locked */
	int door_locked;
	/* the tape hardware is write protected */
	char drv_write_prot;
	/* the tape is write protected (hardware or opened as read-only) */
	char write_prot;
} idetape_tape_t;

static DEFINE_MUTEX(ide_tape_mutex);
static DEFINE_MUTEX(idetape_ref_mutex);

static DEFINE_MUTEX(idetape_chrdev_mutex);

static struct class *idetape_sysfs_class;

static void ide_tape_release(struct device *);

static struct ide_tape_obj *idetape_devs[MAX_HWIFS * MAX_DRIVES];

static struct ide_tape_obj *ide_tape_get(struct gendisk *disk, bool cdev,
					 unsigned int i)
{
	struct ide_tape_obj *tape = NULL;

	mutex_lock(&idetape_ref_mutex);

	if (cdev)
		tape = idetape_devs[i];
	else
		tape = ide_drv_g(disk, ide_tape_obj);

	if (tape) {
		if (ide_device_get(tape->drive))
			tape = NULL;
		else
			get_device(&tape->dev);
	}

	mutex_unlock(&idetape_ref_mutex);
	return tape;
}

static void ide_tape_put(struct ide_tape_obj *tape)
{
	ide_drive_t *drive = tape->drive;

	mutex_lock(&idetape_ref_mutex);
	put_device(&tape->dev);
	ide_device_put(drive);
	mutex_unlock(&idetape_ref_mutex);
}

/*
 * called on each failed packet command retry to analyze the request sense. We
 * currently do not utilize this information.
 */
static void idetape_analyze_error(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	struct ide_atapi_pc *pc = drive->failed_pc;
	struct request *rq = drive->hwif->rq;
	u8 *sense = bio_data(rq->bio);

	tape->sense_key = sense[2] & 0xF;
	tape->asc       = sense[12];
	tape->ascq      = sense[13];

	ide_debug_log(IDE_DBG_FUNC,
		      "cmd: 0x%x, sense key = %x, asc = %x, ascq = %x",
		      rq->cmd[0], tape->sense_key, tape->asc, tape->ascq);

	/* correct remaining bytes to transfer */
	if (pc->flags & PC_FLAG_DMA_ERROR)
		rq->resid_len = tape->blk_size * get_unaligned_be32(&sense[3]);

	/*
	 * If error was the result of a zero-length read or write command,
	 * with sense key=5, asc=0x22, ascq=0, let it slide.  Some drives
	 * (i.e. Seagate STT3401A Travan) don't support 0-length read/writes.
	 */
	if ((pc->c[0] == READ_6 || pc->c[0] == WRITE_6)
	    /* length == 0 */
	    && pc->c[4] == 0 && pc->c[3] == 0 && pc->c[2] == 0) {
		if (tape->sense_key == 5) {
			/* don't report an error, everything's ok */
			pc->error = 0;
			/* don't retry read/write */
			pc->flags |= PC_FLAG_ABORT;
		}
	}
	if (pc->c[0] == READ_6 && (sense[2] & 0x80)) {
		pc->error = IDE_DRV_ERROR_FILEMARK;
		pc->flags |= PC_FLAG_ABORT;
	}
	if (pc->c[0] == WRITE_6) {
		if ((sense[2] & 0x40) || (tape->sense_key == 0xd
		     && tape->asc == 0x0 && tape->ascq == 0x2)) {
			pc->error = IDE_DRV_ERROR_EOD;
			pc->flags |= PC_FLAG_ABORT;
		}
	}
	if (pc->c[0] == READ_6 || pc->c[0] == WRITE_6) {
		if (tape->sense_key == 8) {
			pc->error = IDE_DRV_ERROR_EOD;
			pc->flags |= PC_FLAG_ABORT;
		}
		if (!(pc->flags & PC_FLAG_ABORT) &&
		    (blk_rq_bytes(rq) - rq->resid_len))
			pc->retries = IDETAPE_MAX_PC_RETRIES + 1;
	}
}

static void ide_tape_handle_dsc(ide_drive_t *);

static int ide_tape_callback(ide_drive_t *drive, int dsc)
{
	idetape_tape_t *tape = drive->driver_data;
	struct ide_atapi_pc *pc = drive->pc;
	struct request *rq = drive->hwif->rq;
	int uptodate = pc->error ? 0 : 1;
	int err = uptodate ? 0 : IDE_DRV_ERROR_GENERAL;

	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x, dsc: %d, err: %d", rq->cmd[0],
		      dsc, err);

	if (dsc)
		ide_tape_handle_dsc(drive);

	if (drive->failed_pc == pc)
		drive->failed_pc = NULL;

	if (pc->c[0] == REQUEST_SENSE) {
		if (uptodate)
			idetape_analyze_error(drive);
		else
			printk(KERN_ERR "ide-tape: Error in REQUEST SENSE "
					"itself - Aborting request!\n");
	} else if (pc->c[0] == READ_6 || pc->c[0] == WRITE_6) {
		unsigned int blocks =
			(blk_rq_bytes(rq) - rq->resid_len) / tape->blk_size;

		tape->avg_size += blocks * tape->blk_size;

		if (time_after_eq(jiffies, tape->avg_time + HZ)) {
			tape->avg_speed = tape->avg_size * HZ /
				(jiffies - tape->avg_time) / 1024;
			tape->avg_size = 0;
			tape->avg_time = jiffies;
		}

		tape->first_frame += blocks;

		if (pc->error) {
			uptodate = 0;
			err = pc->error;
		}
	}
	rq->errors = err;

	return uptodate;
}

/*
 * Postpone the current request so that ide.c will be able to service requests
 * from another device on the same port while we are polling for DSC.
 */
static void ide_tape_stall_queue(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x, dsc_poll_freq: %lu",
		      drive->hwif->rq->cmd[0], tape->dsc_poll_freq);

	tape->postponed_rq = true;

	ide_stall_queue(drive, tape->dsc_poll_freq);
}

static void ide_tape_handle_dsc(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

	/* Media access command */
	tape->dsc_polling_start = jiffies;
	tape->dsc_poll_freq = IDETAPE_DSC_MA_FAST;
	tape->dsc_timeout = jiffies + IDETAPE_DSC_MA_TIMEOUT;
	/* Allow ide.c to handle other requests */
	ide_tape_stall_queue(drive);
}

/*
 * Packet Command Interface
 *
 * The current Packet Command is available in drive->pc, and will not change
 * until we finish handling it. Each packet command is associated with a
 * callback function that will be called when the command is finished.
 *
 * The handling will be done in three stages:
 *
 * 1. ide_tape_issue_pc will send the packet command to the drive, and will set
 * the interrupt handler to ide_pc_intr.
 *
 * 2. On each interrupt, ide_pc_intr will be called. This step will be
 * repeated until the device signals us that no more interrupts will be issued.
 *
 * 3. ATAPI Tape media access commands have immediate status with a delayed
 * process. In case of a successful initiation of a media access packet command,
 * the DSC bit will be set when the actual execution of the command is finished.
 * Since the tape drive will not issue an interrupt, we have to poll for this
 * event. In this case, we define the request as "low priority request" by
 * setting rq_status to IDETAPE_RQ_POSTPONED, set a timer to poll for DSC and
 * exit the driver.
 *
 * ide.c will then give higher priority to requests which originate from the
 * other device, until will change rq_status to RQ_ACTIVE.
 *
 * 4. When the packet command is finished, it will be checked for errors.
 *
 * 5. In case an error was found, we queue a request sense packet command in
 * front of the request queue and retry the operation up to
 * IDETAPE_MAX_PC_RETRIES times.
 *
 * 6. In case no error was found, or we decided to give up and not to retry
 * again, the callback function will be called and then we will handle the next
 * request.
 */

static ide_startstop_t ide_tape_issue_pc(ide_drive_t *drive,
					 struct ide_cmd *cmd,
					 struct ide_atapi_pc *pc)
{
	idetape_tape_t *tape = drive->driver_data;
	struct request *rq = drive->hwif->rq;

	if (drive->failed_pc == NULL && pc->c[0] != REQUEST_SENSE)
		drive->failed_pc = pc;

	/* Set the current packet command */
	drive->pc = pc;

	if (pc->retries > IDETAPE_MAX_PC_RETRIES ||
		(pc->flags & PC_FLAG_ABORT)) {

		/*
		 * We will "abort" retrying a packet command in case legitimate
		 * error code was received (crossing a filemark, or end of the
		 * media, for example).
		 */
		if (!(pc->flags & PC_FLAG_ABORT)) {
			if (!(pc->c[0] == TEST_UNIT_READY &&
			      tape->sense_key == 2 && tape->asc == 4 &&
			     (tape->ascq == 1 || tape->ascq == 8))) {
				printk(KERN_ERR "ide-tape: %s: I/O error, "
						"pc = %2x, key = %2x, "
						"asc = %2x, ascq = %2x\n",
						tape->name, pc->c[0],
						tape->sense_key, tape->asc,
						tape->ascq);
			}
			/* Giving up */
			pc->error = IDE_DRV_ERROR_GENERAL;
		}

		drive->failed_pc = NULL;
		drive->pc_callback(drive, 0);
		ide_complete_rq(drive, -EIO, blk_rq_bytes(rq));
		return ide_stopped;
	}
	ide_debug_log(IDE_DBG_SENSE, "retry #%d, cmd: 0x%02x", pc->retries,
		      pc->c[0]);

	pc->retries++;

	return ide_issue_pc(drive, cmd);
}

/* A mode sense command is used to "sense" tape parameters. */
static void idetape_create_mode_sense_cmd(struct ide_atapi_pc *pc, u8 page_code)
{
	ide_init_pc(pc);
	pc->c[0] = MODE_SENSE;
	if (page_code != IDETAPE_BLOCK_DESCRIPTOR)
		/* DBD = 1 - Don't return block descriptors */
		pc->c[1] = 8;
	pc->c[2] = page_code;
	/*
	 * Changed pc->c[3] to 0 (255 will at best return unused info).
	 *
	 * For SCSI this byte is defined as subpage instead of high byte
	 * of length and some IDE drives seem to interpret it this way
	 * and return an error when 255 is used.
	 */
	pc->c[3] = 0;
	/* We will just discard data in that case */
	pc->c[4] = 255;
	if (page_code == IDETAPE_BLOCK_DESCRIPTOR)
		pc->req_xfer = 12;
	else if (page_code == IDETAPE_CAPABILITIES_PAGE)
		pc->req_xfer = 24;
	else
		pc->req_xfer = 50;
}

static ide_startstop_t idetape_media_access_finished(ide_drive_t *drive)
{
	ide_hwif_t *hwif = drive->hwif;
	idetape_tape_t *tape = drive->driver_data;
	struct ide_atapi_pc *pc = drive->pc;
	u8 stat;

	stat = hwif->tp_ops->read_status(hwif);

	if (stat & ATA_DSC) {
		if (stat & ATA_ERR) {
			/* Error detected */
			if (pc->c[0] != TEST_UNIT_READY)
				printk(KERN_ERR "ide-tape: %s: I/O error, ",
						tape->name);
			/* Retry operation */
			ide_retry_pc(drive);
			return ide_stopped;
		}
		pc->error = 0;
	} else {
		pc->error = IDE_DRV_ERROR_GENERAL;
		drive->failed_pc = NULL;
	}
	drive->pc_callback(drive, 0);
	return ide_stopped;
}

static void ide_tape_create_rw_cmd(idetape_tape_t *tape,
				   struct ide_atapi_pc *pc, struct request *rq,
				   u8 opcode)
{
	unsigned int length = blk_rq_sectors(rq) / (tape->blk_size >> 9);

	ide_init_pc(pc);
	put_unaligned(cpu_to_be32(length), (unsigned int *) &pc->c[1]);
	pc->c[1] = 1;

	if (blk_rq_bytes(rq) == tape->buffer_size)
		pc->flags |= PC_FLAG_DMA_OK;

	if (opcode == READ_6)
		pc->c[0] = READ_6;
	else if (opcode == WRITE_6) {
		pc->c[0] = WRITE_6;
		pc->flags |= PC_FLAG_WRITING;
	}

	memcpy(rq->cmd, pc->c, 12);
}

static ide_startstop_t idetape_do_request(ide_drive_t *drive,
					  struct request *rq, sector_t block)
{
	ide_hwif_t *hwif = drive->hwif;
	idetape_tape_t *tape = drive->driver_data;
	struct ide_atapi_pc *pc = NULL;
	struct ide_cmd cmd;
	u8 stat;

	ide_debug_log(IDE_DBG_RQ, "cmd: 0x%x, sector: %llu, nr_sectors: %u",
		      rq->cmd[0], (unsigned long long)blk_rq_pos(rq),
		      blk_rq_sectors(rq));

	BUG_ON(!(rq->cmd_type == REQ_TYPE_DRV_PRIV ||
		 rq->cmd_type == REQ_TYPE_ATA_SENSE));

	/* Retry a failed packet command */
	if (drive->failed_pc && drive->pc->c[0] == REQUEST_SENSE) {
		pc = drive->failed_pc;
		goto out;
	}

	/*
	 * If the tape is still busy, postpone our request and service
	 * the other device meanwhile.
	 */
	stat = hwif->tp_ops->read_status(hwif);

	if ((drive->dev_flags & IDE_DFLAG_DSC_OVERLAP) == 0 &&
	    (rq->cmd[13] & REQ_IDETAPE_PC2) == 0)
		drive->atapi_flags |= IDE_AFLAG_IGNORE_DSC;

	if (drive->dev_flags & IDE_DFLAG_POST_RESET) {
		drive->atapi_flags |= IDE_AFLAG_IGNORE_DSC;
		drive->dev_flags &= ~IDE_DFLAG_POST_RESET;
	}

	if (!(drive->atapi_flags & IDE_AFLAG_IGNORE_DSC) &&
	    !(stat & ATA_DSC)) {
		if (!tape->postponed_rq) {
			tape->dsc_polling_start = jiffies;
			tape->dsc_poll_freq = tape->best_dsc_rw_freq;
			tape->dsc_timeout = jiffies + IDETAPE_DSC_RW_TIMEOUT;
		} else if (time_after(jiffies, tape->dsc_timeout)) {
			printk(KERN_ERR "ide-tape: %s: DSC timeout\n",
				tape->name);
			if (rq->cmd[13] & REQ_IDETAPE_PC2) {
				idetape_media_access_finished(drive);
				return ide_stopped;
			} else {
				return ide_do_reset(drive);
			}
		} else if (time_after(jiffies,
					tape->dsc_polling_start +
					IDETAPE_DSC_MA_THRESHOLD))
			tape->dsc_poll_freq = IDETAPE_DSC_MA_SLOW;
		ide_tape_stall_queue(drive);
		return ide_stopped;
	} else {
		drive->atapi_flags &= ~IDE_AFLAG_IGNORE_DSC;
		tape->postponed_rq = false;
	}

	if (rq->cmd[13] & REQ_IDETAPE_READ) {
		pc = &tape->queued_pc;
		ide_tape_create_rw_cmd(tape, pc, rq, READ_6);
		goto out;
	}
	if (rq->cmd[13] & REQ_IDETAPE_WRITE) {
		pc = &tape->queued_pc;
		ide_tape_create_rw_cmd(tape, pc, rq, WRITE_6);
		goto out;
	}
	if (rq->cmd[13] & REQ_IDETAPE_PC1) {
		pc = (struct ide_atapi_pc *)rq->special;
		rq->cmd[13] &= ~(REQ_IDETAPE_PC1);
		rq->cmd[13] |= REQ_IDETAPE_PC2;
		goto out;
	}
	if (rq->cmd[13] & REQ_IDETAPE_PC2) {
		idetape_media_access_finished(drive);
		return ide_stopped;
	}
	BUG();

out:
	/* prepare sense request for this command */
	ide_prep_sense(drive, rq);

	memset(&cmd, 0, sizeof(cmd));

	if (rq_data_dir(rq))
		cmd.tf_flags |= IDE_TFLAG_WRITE;

	cmd.rq = rq;

	ide_init_sg_cmd(&cmd, blk_rq_bytes(rq));
	ide_map_sg(drive, &cmd);

	return ide_tape_issue_pc(drive, &cmd, pc);
}

/*
 * Write a filemark if write_filemark=1. Flush the device buffers without
 * writing a filemark otherwise.
 */
static void idetape_create_write_filemark_cmd(ide_drive_t *drive,
		struct ide_atapi_pc *pc, int write_filemark)
{
	ide_init_pc(pc);
	pc->c[0] = WRITE_FILEMARKS;
	pc->c[4] = write_filemark;
	pc->flags |= PC_FLAG_WAIT_FOR_DSC;
}

static int idetape_wait_ready(ide_drive_t *drive, unsigned long timeout)
{
	idetape_tape_t *tape = drive->driver_data;
	struct gendisk *disk = tape->disk;
	int load_attempted = 0;

	/* Wait for the tape to become ready */
	set_bit(ilog2(IDE_AFLAG_MEDIUM_PRESENT), &drive->atapi_flags);
	timeout += jiffies;
	while (time_before(jiffies, timeout)) {
		if (ide_do_test_unit_ready(drive, disk) == 0)
			return 0;
		if ((tape->sense_key == 2 && tape->asc == 4 && tape->ascq == 2)
		    || (tape->asc == 0x3A)) {
			/* no media */
			if (load_attempted)
				return -ENOMEDIUM;
			ide_do_start_stop(drive, disk, IDETAPE_LU_LOAD_MASK);
			load_attempted = 1;
		/* not about to be ready */
		} else if (!(tape->sense_key == 2 && tape->asc == 4 &&
			     (tape->ascq == 1 || tape->ascq == 8)))
			return -EIO;
		msleep(100);
	}
	return -EIO;
}

static int idetape_flush_tape_buffers(ide_drive_t *drive)
{
	struct ide_tape_obj *tape = drive->driver_data;
	struct ide_atapi_pc pc;
	int rc;

	idetape_create_write_filemark_cmd(drive, &pc, 0);
	rc = ide_queue_pc_tail(drive, tape->disk, &pc, NULL, 0);
	if (rc)
		return rc;
	idetape_wait_ready(drive, 60 * 5 * HZ);
	return 0;
}

static int ide_tape_read_position(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	struct ide_atapi_pc pc;
	u8 buf[20];

	ide_debug_log(IDE_DBG_FUNC, "enter");

	/* prep cmd */
	ide_init_pc(&pc);
	pc.c[0] = READ_POSITION;
	pc.req_xfer = 20;

	if (ide_queue_pc_tail(drive, tape->disk, &pc, buf, pc.req_xfer))
		return -1;

	if (!pc.error) {
		ide_debug_log(IDE_DBG_FUNC, "BOP - %s",
				(buf[0] & 0x80) ? "Yes" : "No");
		ide_debug_log(IDE_DBG_FUNC, "EOP - %s",
				(buf[0] & 0x40) ? "Yes" : "No");

		if (buf[0] & 0x4) {
			printk(KERN_INFO "ide-tape: Block location is unknown"
					 "to the tape\n");
			clear_bit(ilog2(IDE_AFLAG_ADDRESS_VALID),
				  &drive->atapi_flags);
			return -1;
		} else {
			ide_debug_log(IDE_DBG_FUNC, "Block Location: %u",
				      be32_to_cpup((__be32 *)&buf[4]));

			tape->partition = buf[1];
			tape->first_frame = be32_to_cpup((__be32 *)&buf[4]);
			set_bit(ilog2(IDE_AFLAG_ADDRESS_VALID),
				&drive->atapi_flags);
		}
	}

	return tape->first_frame;
}

static void idetape_create_locate_cmd(ide_drive_t *drive,
		struct ide_atapi_pc *pc,
		unsigned int block, u8 partition, int skip)
{
	ide_init_pc(pc);
	pc->c[0] = POSITION_TO_ELEMENT;
	pc->c[1] = 2;
	put_unaligned(cpu_to_be32(block), (unsigned int *) &pc->c[3]);
	pc->c[8] = partition;
	pc->flags |= PC_FLAG_WAIT_FOR_DSC;
}

static void __ide_tape_discard_merge_buffer(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

	if (tape->chrdev_dir != IDETAPE_DIR_READ)
		return;

	clear_bit(ilog2(IDE_AFLAG_FILEMARK), &drive->atapi_flags);
	tape->valid = 0;
	if (tape->buf != NULL) {
		kfree(tape->buf);
		tape->buf = NULL;
	}

	tape->chrdev_dir = IDETAPE_DIR_NONE;
}

/*
 * Position the tape to the requested block using the LOCATE packet command.
 * A READ POSITION command is then issued to check where we are positioned. Like
 * all higher level operations, we queue the commands at the tail of the request
 * queue and wait for their completion.
 */
static int idetape_position_tape(ide_drive_t *drive, unsigned int block,
		u8 partition, int skip)
{
	idetape_tape_t *tape = drive->driver_data;
	struct gendisk *disk = tape->disk;
	int ret;
	struct ide_atapi_pc pc;

	if (tape->chrdev_dir == IDETAPE_DIR_READ)
		__ide_tape_discard_merge_buffer(drive);
	idetape_wait_ready(drive, 60 * 5 * HZ);
	idetape_create_locate_cmd(drive, &pc, block, partition, skip);
	ret = ide_queue_pc_tail(drive, disk, &pc, NULL, 0);
	if (ret)
		return ret;

	ret = ide_tape_read_position(drive);
	if (ret < 0)
		return ret;
	return 0;
}

static void ide_tape_discard_merge_buffer(ide_drive_t *drive,
					  int restore_position)
{
	idetape_tape_t *tape = drive->driver_data;
	int seek, position;

	__ide_tape_discard_merge_buffer(drive);
	if (restore_position) {
		position = ide_tape_read_position(drive);
		seek = position > 0 ? position : 0;
		if (idetape_position_tape(drive, seek, 0, 0)) {
			printk(KERN_INFO "ide-tape: %s: position_tape failed in"
					 " %s\n", tape->name, __func__);
			return;
		}
	}
}

/*
 * Generate a read/write request for the block device interface and wait for it
 * to be serviced.
 */
static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int size)
{
	idetape_tape_t *tape = drive->driver_data;
	struct request *rq;
	int ret;

	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x, size: %d", cmd, size);

	BUG_ON(cmd != REQ_IDETAPE_READ && cmd != REQ_IDETAPE_WRITE);
	BUG_ON(size < 0 || size % tape->blk_size);

	rq = blk_get_request(drive->queue, READ, __GFP_RECLAIM);
	rq->cmd_type = REQ_TYPE_DRV_PRIV;
	rq->cmd[13] = cmd;
	rq->rq_disk = tape->disk;
	rq->__sector = tape->first_frame;

	if (size) {
		ret = blk_rq_map_kern(drive->queue, rq, tape->buf, size,
				      __GFP_RECLAIM);
		if (ret)
			goto out_put;
	}

	blk_execute_rq(drive->queue, tape->disk, rq, 0);

	/* calculate the number of transferred bytes and update buffer state */
	size -= rq->resid_len;
	tape->cur = tape->buf;
	if (cmd == REQ_IDETAPE_READ)
		tape->valid = size;
	else
		tape->valid = 0;

	ret = size;
	if (rq->errors == IDE_DRV_ERROR_GENERAL)
		ret = -EIO;
out_put:
	blk_put_request(rq);
	return ret;
}

static void idetape_create_inquiry_cmd(struct ide_atapi_pc *pc)
{
	ide_init_pc(pc);
	pc->c[0] = INQUIRY;
	pc->c[4] = 254;
	pc->req_xfer = 254;
}

static void idetape_create_rewind_cmd(ide_drive_t *drive,
		struct ide_atapi_pc *pc)
{
	ide_init_pc(pc);
	pc->c[0] = REZERO_UNIT;
	pc->flags |= PC_FLAG_WAIT_FOR_DSC;
}

static void idetape_create_erase_cmd(struct ide_atapi_pc *pc)
{
	ide_init_pc(pc);
	pc->c[0] = ERASE;
	pc->c[1] = 1;
	pc->flags |= PC_FLAG_WAIT_FOR_DSC;
}

static void idetape_create_space_cmd(struct ide_atapi_pc *pc, int count, u8 cmd)
{
	ide_init_pc(pc);
	pc->c[0] = SPACE;
	put_unaligned(cpu_to_be32(count), (unsigned int *) &pc->c[1]);
	pc->c[1] = cmd;
	pc->flags |= PC_FLAG_WAIT_FOR_DSC;
}

static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

	if (tape->chrdev_dir != IDETAPE_DIR_WRITE) {
		printk(KERN_ERR "ide-tape: bug: Trying to empty merge buffer"
				" but we are not writing.\n");
		return;
	}
	if (tape->buf) {
		size_t aligned = roundup(tape->valid, tape->blk_size);

		memset(tape->cur, 0, aligned - tape->valid);
		idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, aligned);
		kfree(tape->buf);
		tape->buf = NULL;
	}
	tape->chrdev_dir = IDETAPE_DIR_NONE;
}

static int idetape_init_rw(ide_drive_t *drive, int dir)
{
	idetape_tape_t *tape = drive->driver_data;
	int rc;

	BUG_ON(dir != IDETAPE_DIR_READ && dir != IDETAPE_DIR_WRITE);

	if (tape->chrdev_dir == dir)
		return 0;

	if (tape->chrdev_dir == IDETAPE_DIR_READ)
		ide_tape_discard_merge_buffer(drive, 1);
	else if (tape->chrdev_dir == IDETAPE_DIR_WRITE) {
		ide_tape_flush_merge_buffer(drive);
		idetape_flush_tape_buffers(drive);
	}

	if (tape->buf || tape->valid) {
		printk(KERN_ERR "ide-tape: valid should be 0 now\n");
		tape->valid = 0;
	}

	tape->buf = kmalloc(tape->buffer_size, GFP_KERNEL);
	if (!tape->buf)
		return -ENOMEM;
	tape->chrdev_dir = dir;
	tape->cur = tape->buf;

	/*
	 * Issue a 0 rw command to ensure that DSC handshake is
	 * switched from completion mode to buffer available mode.  No
	 * point in issuing this if DSC overlap isn't supported, some
	 * drives (Seagate STT3401A) will return an error.
	 */
	if (drive->dev_flags & IDE_DFLAG_DSC_OVERLAP) {
		int cmd = dir == IDETAPE_DIR_READ ? REQ_IDETAPE_READ
						  : REQ_IDETAPE_WRITE;

		rc = idetape_queue_rw_tail(drive, cmd, 0);
		if (rc < 0) {
			kfree(tape->buf);
			tape->buf = NULL;
			tape->chrdev_dir = IDETAPE_DIR_NONE;
			return rc;
		}
	}

	return 0;
}

static void idetape_pad_zeros(ide_drive_t *drive, int bcount)
{
	idetape_tape_t *tape = drive->driver_data;

	memset(tape->buf, 0, tape->buffer_size);

	while (bcount) {
		unsigned int count = min(tape->buffer_size, bcount);

		idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, count);
		bcount -= count;
	}
}

/*
 * Rewinds the tape to the Beginning Of the current Partition (BOP). We
 * currently support only one partition.
 */
static int idetape_rewind_tape(ide_drive_t *drive)
{
	struct ide_tape_obj *tape = drive->driver_data;
	struct gendisk *disk = tape->disk;
	struct ide_atapi_pc pc;
	int ret;

	ide_debug_log(IDE_DBG_FUNC, "enter");

	idetape_create_rewind_cmd(drive, &pc);
	ret = ide_queue_pc_tail(drive, disk, &pc, NULL, 0);
	if (ret)
		return ret;

	ret = ide_tape_read_position(drive);
	if (ret < 0)
		return ret;
	return 0;
}

/* mtio.h compatible commands should be issued to the chrdev interface. */
static int idetape_blkdev_ioctl(ide_drive_t *drive, unsigned int cmd,
				unsigned long arg)
{
	idetape_tape_t *tape = drive->driver_data;
	void __user *argp = (void __user *)arg;

	struct idetape_config {
		int dsc_rw_frequency;
		int dsc_media_access_frequency;
		int nr_stages;
	} config;

	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%04x", cmd);

	switch (cmd) {
	case 0x0340:
		if (copy_from_user(&config, argp, sizeof(config)))
			return -EFAULT;
		tape->best_dsc_rw_freq = config.dsc_rw_frequency;
		break;
	case 0x0350:
		memset(&config, 0, sizeof(config));
		config.dsc_rw_frequency = (int) tape->best_dsc_rw_freq;
		config.nr_stages = 1;
		if (copy_to_user(argp, &config, sizeof(config)))
			return -EFAULT;
		break;
	default:
		return -EIO;
	}
	return 0;
}

static int idetape_space_over_filemarks(ide_drive_t *drive, short mt_op,
					int mt_count)
{
	idetape_tape_t *tape = drive->driver_data;
	struct gendisk *disk = tape->disk;
	struct ide_atapi_pc pc;
	int retval, count = 0;
	int sprev = !!(tape->caps[4] & 0x20);


	ide_debug_log(IDE_DBG_FUNC, "mt_op: %d, mt_count: %d", mt_op, mt_count);

	if (mt_count == 0)
		return 0;
	if (MTBSF == mt_op || MTBSFM == mt_op) {
		if (!sprev)
			return -EIO;
		mt_count = -mt_count;
	}

	if (tape->chrdev_dir == IDETAPE_DIR_READ) {
		tape->valid = 0;
		if (test_and_clear_bit(ilog2(IDE_AFLAG_FILEMARK),
				       &drive->atapi_flags))
			++count;
		ide_tape_discard_merge_buffer(drive, 0);
	}

	switch (mt_op) {
	case MTFSF:
	case MTBSF:
		idetape_create_space_cmd(&pc, mt_count - count,
					 IDETAPE_SPACE_OVER_FILEMARK);
		return ide_queue_pc_tail(drive, disk, &pc, NULL, 0);
	case MTFSFM:
	case MTBSFM:
		if (!sprev)
			return -EIO;
		retval = idetape_space_over_filemarks(drive, MTFSF,
						      mt_count - count);
		if (retval)
			return retval;
		count = (MTBSFM == mt_op ? 1 : -1);
		return idetape_space_over_filemarks(drive, MTFSF, count);
	default:
		printk(KERN_ERR "ide-tape: MTIO operation %d not supported\n",
				mt_op);
		return -EIO;
	}
}

/*
 * Our character device read / write functions.
 *
 * The tape is optimized to maximize throughput when it is transferring an
 * integral number of the "continuous transfer limit", which is a parameter of
 * the specific tape (26kB on my particular tape, 32kB for Onstream).
 *
 * As of version 1.3 of the driver, the character device provides an abstract
 * continuous view of the media - any mix of block sizes (even 1 byte) on the
 * same backup/restore procedure is supported. The driver will internally
 * convert the requests to the recommended transfer unit, so that an unmatch
 * between the user's block size to the recommended size will only result in a
 * (slightly) increased driver overhead, but will no longer hit performance.
 * This is not applicable to Onstream.
 */
static ssize_t idetape_chrdev_read(struct file *file, char __user *buf,
				   size_t count, loff_t *ppos)
{
	struct ide_tape_obj *tape = file->private_data;
	ide_drive_t *drive = tape->drive;
	size_t done = 0;
	ssize_t ret = 0;
	int rc;

	ide_debug_log(IDE_DBG_FUNC, "count %Zd", count);

	if (tape->chrdev_dir != IDETAPE_DIR_READ) {
		if (test_bit(ilog2(IDE_AFLAG_DETECT_BS), &drive->atapi_flags))
			if (count > tape->blk_size &&
			    (count % tape->blk_size) == 0)
				tape->user_bs_factor = count / tape->blk_size;
	}

	rc = idetape_init_rw(drive, IDETAPE_DIR_READ);
	if (rc < 0)
		return rc;

	while (done < count) {
		size_t todo;

		/* refill if staging buffer is empty */
		if (!tape->valid) {
			/* If we are at a filemark, nothing more to read */
			if (test_bit(ilog2(IDE_AFLAG_FILEMARK),
				     &drive->atapi_flags))
				break;
			/* read */
			if (idetape_queue_rw_tail(drive, REQ_IDETAPE_READ,
						  tape->buffer_size) <= 0)
				break;
		}

		/* copy out */
		todo = min_t(size_t, count - done, tape->valid);
		if (copy_to_user(buf + done, tape->cur, todo))
			ret = -EFAULT;

		tape->cur += todo;
		tape->valid -= todo;
		done += todo;
	}

	if (!done && test_bit(ilog2(IDE_AFLAG_FILEMARK), &drive->atapi_flags)) {
		idetape_space_over_filemarks(drive, MTFSF, 1);
		return 0;
	}

	return ret ? ret : done;
}

static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
				     size_t count, loff_t *ppos)
{
	struct ide_tape_obj *tape = file->private_data;
	ide_drive_t *drive = tape->drive;
	size_t done = 0;
	ssize_t ret = 0;
	int rc;

	/* The drive is write protected. */
	if (tape->write_prot)
		return -EACCES;

	ide_debug_log(IDE_DBG_FUNC, "count %Zd", count);

	/* Initialize write operation */
	rc = idetape_init_rw(drive, IDETAPE_DIR_WRITE);
	if (rc < 0)
		return rc;

	while (done < count) {
		size_t todo;

		/* flush if staging buffer is full */
		if (tape->valid == tape->buffer_size &&
		    idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE,
					  tape->buffer_size) <= 0)
			return rc;

		/* copy in */
		todo = min_t(size_t, count - done,
			     tape->buffer_size - tape->valid);
		if (copy_from_user(tape->cur, buf + done, todo))
			ret = -EFAULT;

		tape->cur += todo;
		tape->valid += todo;
		done += todo;
	}

	return ret ? ret : done;
}

static int idetape_write_filemark(ide_drive_t *drive)
{
	struct ide_tape_obj *tape = drive->driver_data;
	struct ide_atapi_pc pc;

	/* Write a filemark */
	idetape_create_write_filemark_cmd(drive, &pc, 1);
	if (ide_queue_pc_tail(drive, tape->disk, &pc, NULL, 0)) {
		printk(KERN_ERR "ide-tape: Couldn't write a filemark\n");
		return -EIO;
	}
	return 0;
}

/*
 * Called from idetape_chrdev_ioctl when the general mtio MTIOCTOP ioctl is
 * requested.
 *
 * Note: MTBSF and MTBSFM are not supported when the tape doesn't support
 * spacing over filemarks in the reverse direction. In this case, MTFSFM is also
 * usually not supported.
 *
 * The following commands are currently not supported:
 *
 * MTFSS, MTBSS, MTWSM, MTSETDENSITY, MTSETDRVBUFFER, MT_ST_BOOLEANS,
 * MT_ST_WRITE_THRESHOLD.
 */
static int idetape_mtioctop(ide_drive_t *drive, short mt_op, int mt_count)
{
	idetape_tape_t *tape = drive->driver_data;
	struct gendisk *disk = tape->disk;
	struct ide_atapi_pc pc;
	int i, retval;

	ide_debug_log(IDE_DBG_FUNC, "MTIOCTOP ioctl: mt_op: %d, mt_count: %d",
		      mt_op, mt_count);

	switch (mt_op) {
	case MTFSF:
	case MTFSFM:
	case MTBSF:
	case MTBSFM:
		if (!mt_count)
			return 0;
		return idetape_space_over_filemarks(drive, mt_op, mt_count);
	default:
		break;
	}

	switch (mt_op) {
	case MTWEOF:
		if (tape->write_prot)
			return -EACCES;
		ide_tape_discard_merge_buffer(drive, 1);
		for (i = 0; i < mt_count; i++) {
			retval = idetape_write_filemark(drive);
			if (retval)
				return retval;
		}
		return 0;
	case MTREW:
		ide_tape_discard_merge_buffer(drive, 0);
		if (idetape_rewind_tape(drive))
			return -EIO;
		return 0;
	case MTLOAD:
		ide_tape_discard_merge_buffer(drive, 0);
		return ide_do_start_stop(drive, disk, IDETAPE_LU_LOAD_MASK);
	case MTUNLOAD:
	case MTOFFL:
		/*
		 * If door is locked, attempt to unlock before
		 * attempting to eject.
		 */
		if (tape->door_locked) {
			if (!ide_set_media_lock(drive, disk, 0))
				tape->door_locked = DOOR_UNLOCKED;
		}
		ide_tape_discard_merge_buffer(drive, 0);
		retval = ide_do_start_stop(drive, disk, !IDETAPE_LU_LOAD_MASK);
		if (!retval)
			clear_bit(ilog2(IDE_AFLAG_MEDIUM_PRESENT),
				  &drive->atapi_flags);
		return retval;
	case MTNOP:
		ide_tape_discard_merge_buffer(drive, 0);
		return idetape_flush_tape_buffers(drive);
	case MTRETEN:
		ide_tape_discard_merge_buffer(drive, 0);
		return ide_do_start_stop(drive, disk,
			IDETAPE_LU_RETENSION_MASK | IDETAPE_LU_LOAD_MASK);
	case MTEOM:
		idetape_create_space_cmd(&pc, 0, IDETAPE_SPACE_TO_EOD);
		return ide_queue_pc_tail(drive, disk, &pc, NULL, 0);
	case MTERASE:
		(void)idetape_rewind_tape(drive);
		idetape_create_erase_cmd(&pc);
		return ide_queue_pc_tail(drive, disk, &pc, NULL, 0);
	case MTSETBLK:
		if (mt_count) {
			if (mt_count < tape->blk_size ||
			    mt_count % tape->blk_size)
				return -EIO;
			tape->user_bs_factor = mt_count / tape->blk_size;
			clear_bit(ilog2(IDE_AFLAG_DETECT_BS),
				  &drive->atapi_flags);
		} else
			set_bit(ilog2(IDE_AFLAG_DETECT_BS),
				&drive->atapi_flags);
		return 0;
	case MTSEEK:
		ide_tape_discard_merge_buffer(drive, 0);
		return idetape_position_tape(drive,
			mt_count * tape->user_bs_factor, tape->partition, 0);
	case MTSETPART:
		ide_tape_discard_merge_buffer(drive, 0);
		return idetape_position_tape(drive, 0, mt_count, 0);
	case MTFSR:
	case MTBSR:
	case MTLOCK:
		retval = ide_set_media_lock(drive, disk, 1);
		if (retval)
			return retval;
		tape->door_locked = DOOR_EXPLICITLY_LOCKED;
		return 0;
	case MTUNLOCK:
		retval = ide_set_media_lock(drive, disk, 0);
		if (retval)
			return retval;
		tape->door_locked = DOOR_UNLOCKED;
		return 0;
	default:
		printk(KERN_ERR "ide-tape: MTIO operation %d not supported\n",
				mt_op);
		return -EIO;
	}
}

/*
 * Our character device ioctls. General mtio.h magnetic io commands are
 * supported here, and not in the corresponding block interface. Our own
 * ide-tape ioctls are supported on both interfaces.
 */
static long do_idetape_chrdev_ioctl(struct file *file,
				unsigned int cmd, unsigned long arg)
{
	struct ide_tape_obj *tape = file->private_data;
	ide_drive_t *drive = tape->drive;
	struct mtop mtop;
	struct mtget mtget;
	struct mtpos mtpos;
	int block_offset = 0, position = tape->first_frame;
	void __user *argp = (void __user *)arg;

	ide_debug_log(IDE_DBG_FUNC, "cmd: 0x%x", cmd);

	if (tape->chrdev_dir == IDETAPE_DIR_WRITE) {
		ide_tape_flush_merge_buffer(drive);
		idetape_flush_tape_buffers(drive);
	}
	if (cmd == MTIOCGET || cmd == MTIOCPOS) {
		block_offset = tape->valid /
			(tape->blk_size * tape->user_bs_factor);
		position = ide_tape_read_position(drive);
		if (position < 0)
			return -EIO;
	}
	switch (cmd) {
	case MTIOCTOP:
		if (copy_from_user(&mtop, argp, sizeof(struct mtop)))
			return -EFAULT;
		return idetape_mtioctop(drive, mtop.mt_op, mtop.mt_count);
	case MTIOCGET:
		memset(&mtget, 0, sizeof(struct mtget));
		mtget.mt_type = MT_ISSCSI2;
		mtget.mt_blkno = position / tape->user_bs_factor - block_offset;
		mtget.mt_dsreg =
			((tape->blk_size * tape->user_bs_factor)
			 << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK;

		if (tape->drv_write_prot)
			mtget.mt_gstat |= GMT_WR_PROT(0xffffffff);

		if (copy_to_user(argp, &mtget, sizeof(struct mtget)))
			return -EFAULT;
		return 0;
	case MTIOCPOS:
		mtpos.mt_blkno = position / tape->user_bs_factor - block_offset;
		if (copy_to_user(argp, &mtpos, sizeof(struct mtpos)))
			return -EFAULT;
		return 0;
	default:
		if (tape->chrdev_dir == IDETAPE_DIR_READ)
			ide_tape_discard_merge_buffer(drive, 1);
		return idetape_blkdev_ioctl(drive, cmd, arg);
	}
}

static long idetape_chrdev_ioctl(struct file *file,
				unsigned int cmd, unsigned long arg)
{
	long ret;
	mutex_lock(&ide_tape_mutex);
	ret = do_idetape_chrdev_ioctl(file, cmd, arg);
	mutex_unlock(&ide_tape_mutex);
	return ret;
}

/*
 * Do a mode sense page 0 with block descriptor and if it succeeds set the tape
 * block size with the reported value.
 */
static void ide_tape_get_bsize_from_bdesc(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	struct ide_atapi_pc pc;
	u8 buf[12];

	idetape_create_mode_sense_cmd(&pc, IDETAPE_BLOCK_DESCRIPTOR);
	if (ide_queue_pc_tail(drive, tape->disk, &pc, buf, pc.req_xfer)) {
		printk(KERN_ERR "ide-tape: Can't get block descriptor\n");
		if (tape->blk_size == 0) {
			printk(KERN_WARNING "ide-tape: Cannot deal with zero "
					    "block size, assuming 32k\n");
			tape->blk_size = 32768;
		}
		return;
	}
	tape->blk_size = (buf[4 + 5] << 16) +
				(buf[4 + 6] << 8)  +
				 buf[4 + 7];
	tape->drv_write_prot = (buf[2] & 0x80) >> 7;

	ide_debug_log(IDE_DBG_FUNC, "blk_size: %d, write_prot: %d",
		      tape->blk_size, tape->drv_write_prot);
}

static int idetape_chrdev_open(struct inode *inode, struct file *filp)
{
	unsigned int minor = iminor(inode), i = minor & ~0xc0;
	ide_drive_t *drive;
	idetape_tape_t *tape;
	int retval;

	if (i >= MAX_HWIFS * MAX_DRIVES)
		return -ENXIO;

	mutex_lock(&idetape_chrdev_mutex);

	tape = ide_tape_get(NULL, true, i);
	if (!tape) {
		mutex_unlock(&idetape_chrdev_mutex);
		return -ENXIO;
	}

	drive = tape->drive;
	filp->private_data = tape;

	ide_debug_log(IDE_DBG_FUNC, "enter");

	/*
	 * We really want to do nonseekable_open(inode, filp); here, but some
	 * versions of tar incorrectly call lseek on tapes and bail out if that
	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
	 */
	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);


	if (test_and_set_bit(ilog2(IDE_AFLAG_BUSY), &drive->atapi_flags)) {
		retval = -EBUSY;
		goto out_put_tape;
	}

	retval = idetape_wait_ready(drive, 60 * HZ);
	if (retval) {
		clear_bit(ilog2(IDE_AFLAG_BUSY), &drive->atapi_flags);
		printk(KERN_ERR "ide-tape: %s: drive not ready\n", tape->name);
		goto out_put_tape;
	}

	ide_tape_read_position(drive);
	if (!test_bit(ilog2(IDE_AFLAG_ADDRESS_VALID), &drive->atapi_flags))
		(void)idetape_rewind_tape(drive);

	/* Read block size and write protect status from drive. */
	ide_tape_get_bsize_from_bdesc(drive);

	/* Set write protect flag if device is opened as read-only. */
	if ((filp->f_flags & O_ACCMODE) == O_RDONLY)
		tape->write_prot = 1;
	else
		tape->write_prot = tape->drv_write_prot;

	/* Make sure drive isn't write protected if user wants to write. */
	if (tape->write_prot) {
		if ((filp->f_flags & O_ACCMODE) == O_WRONLY ||
		    (filp->f_flags & O_ACCMODE) == O_RDWR) {
			clear_bit(ilog2(IDE_AFLAG_BUSY), &drive->atapi_flags);
			retval = -EROFS;
			goto out_put_tape;
		}
	}

	/* Lock the tape drive door so user can't eject. */
	if (tape->chrdev_dir == IDETAPE_DIR_NONE) {
		if (!ide_set_media_lock(drive, tape->disk, 1)) {
			if (tape->door_locked != DOOR_EXPLICITLY_LOCKED)
				tape->door_locked = DOOR_LOCKED;
		}
	}
	mutex_unlock(&idetape_chrdev_mutex);

	return 0;

out_put_tape:
	ide_tape_put(tape);

	mutex_unlock(&idetape_chrdev_mutex);

	return retval;
}

static void idetape_write_release(ide_drive_t *drive, unsigned int minor)
{
	idetape_tape_t *tape = drive->driver_data;

	ide_tape_flush_merge_buffer(drive);
	tape->buf = kmalloc(tape->buffer_size, GFP_KERNEL);
	if (tape->buf != NULL) {
		idetape_pad_zeros(drive, tape->blk_size *
				(tape->user_bs_factor - 1));
		kfree(tape->buf);
		tape->buf = NULL;
	}
	idetape_write_filemark(drive);
	idetape_flush_tape_buffers(drive);
	idetape_flush_tape_buffers(drive);
}

static int idetape_chrdev_release(struct inode *inode, struct file *filp)
{
	struct ide_tape_obj *tape = filp->private_data;
	ide_drive_t *drive = tape->drive;
	unsigned int minor = iminor(inode);

	mutex_lock(&idetape_chrdev_mutex);

	tape = drive->driver_data;

	ide_debug_log(IDE_DBG_FUNC, "enter");

	if (tape->chrdev_dir == IDETAPE_DIR_WRITE)
		idetape_write_release(drive, minor);
	if (tape->chrdev_dir == IDETAPE_DIR_READ) {
		if (minor < 128)
			ide_tape_discard_merge_buffer(drive, 1);
	}

	if (minor < 128 && test_bit(ilog2(IDE_AFLAG_MEDIUM_PRESENT),
				    &drive->atapi_flags))
		(void) idetape_rewind_tape(drive);

	if (tape->chrdev_dir == IDETAPE_DIR_NONE) {
		if (tape->door_locked == DOOR_LOCKED) {
			if (!ide_set_media_lock(drive, tape->disk, 0))
				tape->door_locked = DOOR_UNLOCKED;
		}
	}
	clear_bit(ilog2(IDE_AFLAG_BUSY), &drive->atapi_flags);
	ide_tape_put(tape);

	mutex_unlock(&idetape_chrdev_mutex);

	return 0;
}

static void idetape_get_inquiry_results(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	struct ide_atapi_pc pc;
	u8 pc_buf[256];
	char fw_rev[4], vendor_id[8], product_id[16];

	idetape_create_inquiry_cmd(&pc);
	if (ide_queue_pc_tail(drive, tape->disk, &pc, pc_buf, pc.req_xfer)) {
		printk(KERN_ERR "ide-tape: %s: can't get INQUIRY results\n",
				tape->name);
		return;
	}
	memcpy(vendor_id, &pc_buf[8], 8);
	memcpy(product_id, &pc_buf[16], 16);
	memcpy(fw_rev, &pc_buf[32], 4);

	ide_fixstring(vendor_id, 8, 0);
	ide_fixstring(product_id, 16, 0);
	ide_fixstring(fw_rev, 4, 0);

	printk(KERN_INFO "ide-tape: %s <-> %s: %.8s %.16s rev %.4s\n",
			drive->name, tape->name, vendor_id, product_id, fw_rev);
}

/*
 * Ask the tape about its various parameters. In particular, we will adjust our
 * data transfer buffer	size to the recommended value as returned by the tape.
 */
static void idetape_get_mode_sense_results(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	struct ide_atapi_pc pc;
	u8 buf[24], *caps;
	u8 speed, max_speed;

	idetape_create_mode_sense_cmd(&pc, IDETAPE_CAPABILITIES_PAGE);
	if (ide_queue_pc_tail(drive, tape->disk, &pc, buf, pc.req_xfer)) {
		printk(KERN_ERR "ide-tape: Can't get tape parameters - assuming"
				" some default values\n");
		tape->blk_size = 512;
		put_unaligned(52,   (u16 *)&tape->caps[12]);
		put_unaligned(540,  (u16 *)&tape->caps[14]);
		put_unaligned(6*52, (u16 *)&tape->caps[16]);
		return;
	}
	caps = buf + 4 + buf[3];

	/* convert to host order and save for later use */
	speed = be16_to_cpup((__be16 *)&caps[14]);
	max_speed = be16_to_cpup((__be16 *)&caps[8]);

	*(u16 *)&caps[8] = max_speed;
	*(u16 *)&caps[12] = be16_to_cpup((__be16 *)&caps[12]);
	*(u16 *)&caps[14] = speed;
	*(u16 *)&caps[16] = be16_to_cpup((__be16 *)&caps[16]);

	if (!speed) {
		printk(KERN_INFO "ide-tape: %s: invalid tape speed "
				"(assuming 650KB/sec)\n", drive->name);
		*(u16 *)&caps[14] = 650;
	}
	if (!max_speed) {
		printk(KERN_INFO "ide-tape: %s: invalid max_speed "
				"(assuming 650KB/sec)\n", drive->name);
		*(u16 *)&caps[8] = 650;
	}

	memcpy(&tape->caps, caps, 20);

	/* device lacks locking support according to capabilities page */
	if ((caps[6] & 1) == 0)
		drive->dev_flags &= ~IDE_DFLAG_DOORLOCKING;

	if (caps[7] & 0x02)
		tape->blk_size = 512;
	else if (caps[7] & 0x04)
		tape->blk_size = 1024;
}

#ifdef CONFIG_IDE_PROC_FS
#define ide_tape_devset_get(name, field) \
static int get_##name(ide_drive_t *drive) \
{ \
	idetape_tape_t *tape = drive->driver_data; \
	return tape->field; \
}

#define ide_tape_devset_set(name, field) \
static int set_##name(ide_drive_t *drive, int arg) \
{ \
	idetape_tape_t *tape = drive->driver_data; \
	tape->field = arg; \
	return 0; \
}

#define ide_tape_devset_rw_field(_name, _field) \
ide_tape_devset_get(_name, _field) \
ide_tape_devset_set(_name, _field) \
IDE_DEVSET(_name, DS_SYNC, get_##_name, set_##_name)

#define ide_tape_devset_r_field(_name, _field) \
ide_tape_devset_get(_name, _field) \
IDE_DEVSET(_name, 0, get_##_name, NULL)

static int mulf_tdsc(ide_drive_t *drive)	{ return 1000; }
static int divf_tdsc(ide_drive_t *drive)	{ return   HZ; }
static int divf_buffer(ide_drive_t *drive)	{ return    2; }
static int divf_buffer_size(ide_drive_t *drive)	{ return 1024; }

ide_devset_rw_flag(dsc_overlap, IDE_DFLAG_DSC_OVERLAP);

ide_tape_devset_rw_field(tdsc, best_dsc_rw_freq);

ide_tape_devset_r_field(avg_speed, avg_speed);
ide_tape_devset_r_field(speed, caps[14]);
ide_tape_devset_r_field(buffer, caps[16]);
ide_tape_devset_r_field(buffer_size, buffer_size);

static const struct ide_proc_devset idetape_settings[] = {
	__IDE_PROC_DEVSET(avg_speed,	0, 0xffff, NULL, NULL),
	__IDE_PROC_DEVSET(buffer,	0, 0xffff, NULL, divf_buffer),
	__IDE_PROC_DEVSET(buffer_size,	0, 0xffff, NULL, divf_buffer_size),
	__IDE_PROC_DEVSET(dsc_overlap,	0,      1, NULL, NULL),
	__IDE_PROC_DEVSET(speed,	0, 0xffff, NULL, NULL),
	__IDE_PROC_DEVSET(tdsc,		IDETAPE_DSC_RW_MIN, IDETAPE_DSC_RW_MAX,
					mulf_tdsc, divf_tdsc),
	{ NULL },
};
#endif

/*
 * The function below is called to:
 *
 * 1. Initialize our various state variables.
 * 2. Ask the tape for its capabilities.
 * 3. Allocate a buffer which will be used for data transfer. The buffer size
 * is chosen based on the recommendation which we received in step 2.
 *
 * Note that at this point ide.c already assigned us an irq, so that we can
 * queue requests here and wait for their completion.
 */
static void idetape_setup(ide_drive_t *drive, idetape_tape_t *tape, int minor)
{
	unsigned long t;
	int speed;
	int buffer_size;
	u16 *ctl = (u16 *)&tape->caps[12];

	ide_debug_log(IDE_DBG_FUNC, "minor: %d", minor);

	drive->pc_callback = ide_tape_callback;

	drive->dev_flags |= IDE_DFLAG_DSC_OVERLAP;

	if (drive->hwif->host_flags & IDE_HFLAG_NO_DSC) {
		printk(KERN_INFO "ide-tape: %s: disabling DSC overlap\n",
				 tape->name);
		drive->dev_flags &= ~IDE_DFLAG_DSC_OVERLAP;
	}

	/* Seagate Travan drives do not support DSC overlap. */
	if (strstr((char *)&drive->id[ATA_ID_PROD], "Seagate STT3401"))
		drive->dev_flags &= ~IDE_DFLAG_DSC_OVERLAP;

	tape->minor = minor;
	tape->name[0] = 'h';
	tape->name[1] = 't';
	tape->name[2] = '0' + minor;
	tape->chrdev_dir = IDETAPE_DIR_NONE;

	idetape_get_inquiry_results(drive);
	idetape_get_mode_sense_results(drive);
	ide_tape_get_bsize_from_bdesc(drive);
	tape->user_bs_factor = 1;
	tape->buffer_size = *ctl * tape->blk_size;
	while (tape->buffer_size > 0xffff) {
		printk(KERN_NOTICE "ide-tape: decreasing stage size\n");
		*ctl /= 2;
		tape->buffer_size = *ctl * tape->blk_size;
	}
	buffer_size = tape->buffer_size;

	/* select the "best" DSC read/write polling freq */
	speed = max(*(u16 *)&tape->caps[14], *(u16 *)&tape->caps[8]);

	t = (IDETAPE_FIFO_THRESHOLD * tape->buffer_size * HZ) / (speed * 1000);

	/*
	 * Ensure that the number we got makes sense; limit it within
	 * IDETAPE_DSC_RW_MIN and IDETAPE_DSC_RW_MAX.
	 */
	tape->best_dsc_rw_freq = clamp_t(unsigned long, t, IDETAPE_DSC_RW_MIN,
					 IDETAPE_DSC_RW_MAX);
	printk(KERN_INFO "ide-tape: %s <-> %s: %dKBps, %d*%dkB buffer, "
		"%ums tDSC%s\n",
		drive->name, tape->name, *(u16 *)&tape->caps[14],
		(*(u16 *)&tape->caps[16] * 512) / tape->buffer_size,
		tape->buffer_size / 1024,
		jiffies_to_msecs(tape->best_dsc_rw_freq),
		(drive->dev_flags & IDE_DFLAG_USING_DMA) ? ", DMA" : "");

	ide_proc_register_driver(drive, tape->driver);
}

static void ide_tape_remove(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

	ide_proc_unregister_driver(drive, tape->driver);
	device_del(&tape->dev);
	ide_unregister_region(tape->disk);

	mutex_lock(&idetape_ref_mutex);
	put_device(&tape->dev);
	mutex_unlock(&idetape_ref_mutex);
}

static void ide_tape_release(struct device *dev)
{
	struct ide_tape_obj *tape = to_ide_drv(dev, ide_tape_obj);
	ide_drive_t *drive = tape->drive;
	struct gendisk *g = tape->disk;

	BUG_ON(tape->valid);

	drive->dev_flags &= ~IDE_DFLAG_DSC_OVERLAP;
	drive->driver_data = NULL;
	device_destroy(idetape_sysfs_class, MKDEV(IDETAPE_MAJOR, tape->minor));
	device_destroy(idetape_sysfs_class,
			MKDEV(IDETAPE_MAJOR, tape->minor + 128));
	idetape_devs[tape->minor] = NULL;
	g->private_data = NULL;
	put_disk(g);
	kfree(tape);
}

#ifdef CONFIG_IDE_PROC_FS
static int idetape_name_proc_show(struct seq_file *m, void *v)
{
	ide_drive_t	*drive = (ide_drive_t *) m->private;
	idetape_tape_t	*tape = drive->driver_data;

	seq_printf(m, "%s\n", tape->name);
	return 0;
}

static int idetape_name_proc_open(struct inode *inode, struct file *file)
{
	return single_open(file, idetape_name_proc_show, PDE_DATA(inode));
}

static const struct file_operations idetape_name_proc_fops = {
	.owner		= THIS_MODULE,
	.open		= idetape_name_proc_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static ide_proc_entry_t idetape_proc[] = {
	{ "capacity",	S_IFREG|S_IRUGO,	&ide_capacity_proc_fops	},
	{ "name",	S_IFREG|S_IRUGO,	&idetape_name_proc_fops	},
	{}
};

static ide_proc_entry_t *ide_tape_proc_entries(ide_drive_t *drive)
{
	return idetape_proc;
}

static const struct ide_proc_devset *ide_tape_proc_devsets(ide_drive_t *drive)
{
	return idetape_settings;
}
#endif

static int ide_tape_probe(ide_drive_t *);

static struct ide_driver idetape_driver = {
	.gen_driver = {
		.owner		= THIS_MODULE,
		.name		= "ide-tape",
		.bus		= &ide_bus_type,
	},
	.probe			= ide_tape_probe,
	.remove			= ide_tape_remove,
	.version		= IDETAPE_VERSION,
	.do_request		= idetape_do_request,
#ifdef CONFIG_IDE_PROC_FS
	.proc_entries		= ide_tape_proc_entries,
	.proc_devsets		= ide_tape_proc_devsets,
#endif
};

/* Our character device supporting functions, passed to register_chrdev. */
static const struct file_operations idetape_fops = {
	.owner		= THIS_MODULE,
	.read		= idetape_chrdev_read,
	.write		= idetape_chrdev_write,
	.unlocked_ioctl	= idetape_chrdev_ioctl,
	.open		= idetape_chrdev_open,
	.release	= idetape_chrdev_release,
	.llseek		= noop_llseek,
};

static int idetape_open(struct block_device *bdev, fmode_t mode)
{
	struct ide_tape_obj *tape;

	mutex_lock(&ide_tape_mutex);
	tape = ide_tape_get(bdev->bd_disk, false, 0);
	mutex_unlock(&ide_tape_mutex);

	if (!tape)
		return -ENXIO;

	return 0;
}

static void idetape_release(struct gendisk *disk, fmode_t mode)
{
	struct ide_tape_obj *tape = ide_drv_g(disk, ide_tape_obj);

	mutex_lock(&ide_tape_mutex);
	ide_tape_put(tape);
	mutex_unlock(&ide_tape_mutex);
}

static int idetape_ioctl(struct block_device *bdev, fmode_t mode,
			unsigned int cmd, unsigned long arg)
{
	struct ide_tape_obj *tape = ide_drv_g(bdev->bd_disk, ide_tape_obj);
	ide_drive_t *drive = tape->drive;
	int err;

	mutex_lock(&ide_tape_mutex);
	err = generic_ide_ioctl(drive, bdev, cmd, arg);
	if (err == -EINVAL)
		err = idetape_blkdev_ioctl(drive, cmd, arg);
	mutex_unlock(&ide_tape_mutex);

	return err;
}

static const struct block_device_operations idetape_block_ops = {
	.owner		= THIS_MODULE,
	.open		= idetape_open,
	.release	= idetape_release,
	.ioctl		= idetape_ioctl,
};

static int ide_tape_probe(ide_drive_t *drive)
{
	idetape_tape_t *tape;
	struct gendisk *g;
	int minor;

	ide_debug_log(IDE_DBG_FUNC, "enter");

	if (!strstr(DRV_NAME, drive->driver_req))
		goto failed;

	if (drive->media != ide_tape)
		goto failed;

	if ((drive->dev_flags & IDE_DFLAG_ID_READ) &&
	    ide_check_atapi_device(drive, DRV_NAME) == 0) {
		printk(KERN_ERR "ide-tape: %s: not supported by this version of"
				" the driver\n", drive->name);
		goto failed;
	}
	tape = kzalloc(sizeof(idetape_tape_t), GFP_KERNEL);
	if (tape == NULL) {
		printk(KERN_ERR "ide-tape: %s: Can't allocate a tape struct\n",
				drive->name);
		goto failed;
	}

	g = alloc_disk(1 << PARTN_BITS);
	if (!g)
		goto out_free_tape;

	ide_init_disk(g, drive);

	tape->dev.parent = &drive->gendev;
	tape->dev.release = ide_tape_release;
	dev_set_name(&tape->dev, "%s", dev_name(&drive->gendev));

	if (device_register(&tape->dev))
		goto out_free_disk;

	tape->drive = drive;
	tape->driver = &idetape_driver;
	tape->disk = g;

	g->private_data = &tape->driver;

	drive->driver_data = tape;

	mutex_lock(&idetape_ref_mutex);
	for (minor = 0; idetape_devs[minor]; minor++)
		;
	idetape_devs[minor] = tape;
	mutex_unlock(&idetape_ref_mutex);

	idetape_setup(drive, tape, minor);

	device_create(idetape_sysfs_class, &drive->gendev,
		      MKDEV(IDETAPE_MAJOR, minor), NULL, "%s", tape->name);
	device_create(idetape_sysfs_class, &drive->gendev,
		      MKDEV(IDETAPE_MAJOR, minor + 128), NULL,
		      "n%s", tape->name);

	g->fops = &idetape_block_ops;
	ide_register_region(g);

	return 0;

out_free_disk:
	put_disk(g);
out_free_tape:
	kfree(tape);
failed:
	return -ENODEV;
}

static void __exit idetape_exit(void)
{
	driver_unregister(&idetape_driver.gen_driver);
	class_destroy(idetape_sysfs_class);
	unregister_chrdev(IDETAPE_MAJOR, "ht");
}

static int __init idetape_init(void)
{
	int error = 1;
	idetape_sysfs_class = class_create(THIS_MODULE, "ide_tape");
	if (IS_ERR(idetape_sysfs_class)) {
		idetape_sysfs_class = NULL;
		printk(KERN_ERR "Unable to create sysfs class for ide tapes\n");
		error = -EBUSY;
		goto out;
	}

	if (register_chrdev(IDETAPE_MAJOR, "ht", &idetape_fops)) {
		printk(KERN_ERR "ide-tape: Failed to register chrdev"
				" interface\n");
		error = -EBUSY;
		goto out_free_class;
	}

	error = driver_register(&idetape_driver.gen_driver);
	if (error)
		goto out_free_driver;

	return 0;

out_free_driver:
	driver_unregister(&idetape_driver.gen_driver);
out_free_class:
	class_destroy(idetape_sysfs_class);
out:
	return error;
}

MODULE_ALIAS("ide:*m-tape*");
module_init(idetape_init);
module_exit(idetape_exit);
MODULE_ALIAS_CHARDEV_MAJOR(IDETAPE_MAJOR);
MODULE_DESCRIPTION("ATAPI Streaming TAPE Driver");
MODULE_LICENSE("GPL");