1 #ifndef _SCSI_SCSI_HOST_H 2 #define _SCSI_SCSI_HOST_H 3 4 #include <linux/device.h> 5 #include <linux/list.h> 6 #include <linux/types.h> 7 #include <linux/workqueue.h> 8 #include <linux/mutex.h> 9 10 struct request_queue; 11 struct block_device; 12 struct completion; 13 struct module; 14 struct scsi_cmnd; 15 struct scsi_device; 16 struct scsi_target; 17 struct Scsi_Host; 18 struct scsi_host_cmd_pool; 19 struct scsi_transport_template; 20 struct blk_queue_tags; 21 22 23 /* 24 * The various choices mean: 25 * NONE: Self evident. Host adapter is not capable of scatter-gather. 26 * ALL: Means that the host adapter module can do scatter-gather, 27 * and that there is no limit to the size of the table to which 28 * we scatter/gather data. 29 * Anything else: Indicates the maximum number of chains that can be 30 * used in one scatter-gather request. 31 */ 32 #define SG_NONE 0 33 #define SG_ALL 0xff 34 35 36 #define DISABLE_CLUSTERING 0 37 #define ENABLE_CLUSTERING 1 38 39 enum scsi_eh_timer_return { 40 EH_NOT_HANDLED, 41 EH_HANDLED, 42 EH_RESET_TIMER, 43 }; 44 45 46 struct scsi_host_template { 47 struct module *module; 48 const char *name; 49 50 /* 51 * Used to initialize old-style drivers. For new-style drivers 52 * just perform all work in your module initialization function. 53 * 54 * Status: OBSOLETE 55 */ 56 int (* detect)(struct scsi_host_template *); 57 58 /* 59 * Used as unload callback for hosts with old-style drivers. 60 * 61 * Status: OBSOLETE 62 */ 63 int (* release)(struct Scsi_Host *); 64 65 /* 66 * The info function will return whatever useful information the 67 * developer sees fit. If not provided, then the name field will 68 * be used instead. 69 * 70 * Status: OPTIONAL 71 */ 72 const char *(* info)(struct Scsi_Host *); 73 74 /* 75 * Ioctl interface 76 * 77 * Status: OPTIONAL 78 */ 79 int (* ioctl)(struct scsi_device *dev, int cmd, void __user *arg); 80 81 82 #ifdef CONFIG_COMPAT 83 /* 84 * Compat handler. Handle 32bit ABI. 85 * When unknown ioctl is passed return -ENOIOCTLCMD. 86 * 87 * Status: OPTIONAL 88 */ 89 int (* compat_ioctl)(struct scsi_device *dev, int cmd, void __user *arg); 90 #endif 91 92 /* 93 * The queuecommand function is used to queue up a scsi 94 * command block to the LLDD. When the driver finished 95 * processing the command the done callback is invoked. 96 * 97 * If queuecommand returns 0, then the HBA has accepted the 98 * command. The done() function must be called on the command 99 * when the driver has finished with it. (you may call done on the 100 * command before queuecommand returns, but in this case you 101 * *must* return 0 from queuecommand). 102 * 103 * Queuecommand may also reject the command, in which case it may 104 * not touch the command and must not call done() for it. 105 * 106 * There are two possible rejection returns: 107 * 108 * SCSI_MLQUEUE_DEVICE_BUSY: Block this device temporarily, but 109 * allow commands to other devices serviced by this host. 110 * 111 * SCSI_MLQUEUE_HOST_BUSY: Block all devices served by this 112 * host temporarily. 113 * 114 * For compatibility, any other non-zero return is treated the 115 * same as SCSI_MLQUEUE_HOST_BUSY. 116 * 117 * NOTE: "temporarily" means either until the next command for# 118 * this device/host completes, or a period of time determined by 119 * I/O pressure in the system if there are no other outstanding 120 * commands. 121 * 122 * STATUS: REQUIRED 123 */ 124 int (* queuecommand)(struct scsi_cmnd *, 125 void (*done)(struct scsi_cmnd *)); 126 127 /* 128 * The transfer functions are used to queue a scsi command to 129 * the LLD. When the driver is finished processing the command 130 * the done callback is invoked. 131 * 132 * return values: see queuecommand 133 * 134 * If the LLD accepts the cmd, it should set the result to an 135 * appropriate value when completed before calling the done function. 136 * 137 * STATUS: REQUIRED FOR TARGET DRIVERS 138 */ 139 /* TODO: rename */ 140 int (* transfer_response)(struct scsi_cmnd *, 141 void (*done)(struct scsi_cmnd *)); 142 /* 143 * This is called to inform the LLD to transfer cmd->request_bufflen 144 * bytes of the cmd at cmd->offset in the cmd. The cmd->use_sg 145 * speciefies the number of scatterlist entried in the command 146 * and cmd->request_buffer contains the scatterlist. 147 * 148 * If the command cannot be processed in one transfer_data call 149 * becuase a scatterlist within the LLD's limits cannot be 150 * created then transfer_data will be called multiple times. 151 * It is initially called from process context, and later 152 * calls are from the interrup context. 153 */ 154 int (* transfer_data)(struct scsi_cmnd *, 155 void (*done)(struct scsi_cmnd *)); 156 157 /* Used as callback for the completion of task management request. */ 158 int (* tsk_mgmt_response)(u64 mid, int result); 159 160 /* 161 * This is an error handling strategy routine. You don't need to 162 * define one of these if you don't want to - there is a default 163 * routine that is present that should work in most cases. For those 164 * driver authors that have the inclination and ability to write their 165 * own strategy routine, this is where it is specified. Note - the 166 * strategy routine is *ALWAYS* run in the context of the kernel eh 167 * thread. Thus you are guaranteed to *NOT* be in an interrupt 168 * handler when you execute this, and you are also guaranteed to 169 * *NOT* have any other commands being queued while you are in the 170 * strategy routine. When you return from this function, operations 171 * return to normal. 172 * 173 * See scsi_error.c scsi_unjam_host for additional comments about 174 * what this function should and should not be attempting to do. 175 * 176 * Status: REQUIRED (at least one of them) 177 */ 178 int (* eh_abort_handler)(struct scsi_cmnd *); 179 int (* eh_device_reset_handler)(struct scsi_cmnd *); 180 int (* eh_bus_reset_handler)(struct scsi_cmnd *); 181 int (* eh_host_reset_handler)(struct scsi_cmnd *); 182 183 /* 184 * Before the mid layer attempts to scan for a new device where none 185 * currently exists, it will call this entry in your driver. Should 186 * your driver need to allocate any structs or perform any other init 187 * items in order to send commands to a currently unused target/lun 188 * combo, then this is where you can perform those allocations. This 189 * is specifically so that drivers won't have to perform any kind of 190 * "is this a new device" checks in their queuecommand routine, 191 * thereby making the hot path a bit quicker. 192 * 193 * Return values: 0 on success, non-0 on failure 194 * 195 * Deallocation: If we didn't find any devices at this ID, you will 196 * get an immediate call to slave_destroy(). If we find something 197 * here then you will get a call to slave_configure(), then the 198 * device will be used for however long it is kept around, then when 199 * the device is removed from the system (or * possibly at reboot 200 * time), you will then get a call to slave_destroy(). This is 201 * assuming you implement slave_configure and slave_destroy. 202 * However, if you allocate memory and hang it off the device struct, 203 * then you must implement the slave_destroy() routine at a minimum 204 * in order to avoid leaking memory 205 * each time a device is tore down. 206 * 207 * Status: OPTIONAL 208 */ 209 int (* slave_alloc)(struct scsi_device *); 210 211 /* 212 * Once the device has responded to an INQUIRY and we know the 213 * device is online, we call into the low level driver with the 214 * struct scsi_device *. If the low level device driver implements 215 * this function, it *must* perform the task of setting the queue 216 * depth on the device. All other tasks are optional and depend 217 * on what the driver supports and various implementation details. 218 * 219 * Things currently recommended to be handled at this time include: 220 * 221 * 1. Setting the device queue depth. Proper setting of this is 222 * described in the comments for scsi_adjust_queue_depth. 223 * 2. Determining if the device supports the various synchronous 224 * negotiation protocols. The device struct will already have 225 * responded to INQUIRY and the results of the standard items 226 * will have been shoved into the various device flag bits, eg. 227 * device->sdtr will be true if the device supports SDTR messages. 228 * 3. Allocating command structs that the device will need. 229 * 4. Setting the default timeout on this device (if needed). 230 * 5. Anything else the low level driver might want to do on a device 231 * specific setup basis... 232 * 6. Return 0 on success, non-0 on error. The device will be marked 233 * as offline on error so that no access will occur. If you return 234 * non-0, your slave_destroy routine will never get called for this 235 * device, so don't leave any loose memory hanging around, clean 236 * up after yourself before returning non-0 237 * 238 * Status: OPTIONAL 239 */ 240 int (* slave_configure)(struct scsi_device *); 241 242 /* 243 * Immediately prior to deallocating the device and after all activity 244 * has ceased the mid layer calls this point so that the low level 245 * driver may completely detach itself from the scsi device and vice 246 * versa. The low level driver is responsible for freeing any memory 247 * it allocated in the slave_alloc or slave_configure calls. 248 * 249 * Status: OPTIONAL 250 */ 251 void (* slave_destroy)(struct scsi_device *); 252 253 /* 254 * Before the mid layer attempts to scan for a new device attached 255 * to a target where no target currently exists, it will call this 256 * entry in your driver. Should your driver need to allocate any 257 * structs or perform any other init items in order to send commands 258 * to a currently unused target, then this is where you can perform 259 * those allocations. 260 * 261 * Return values: 0 on success, non-0 on failure 262 * 263 * Status: OPTIONAL 264 */ 265 int (* target_alloc)(struct scsi_target *); 266 267 /* 268 * Immediately prior to deallocating the target structure, and 269 * after all activity to attached scsi devices has ceased, the 270 * midlayer calls this point so that the driver may deallocate 271 * and terminate any references to the target. 272 * 273 * Status: OPTIONAL 274 */ 275 void (* target_destroy)(struct scsi_target *); 276 277 /* 278 * If a host has the ability to discover targets on its own instead 279 * of scanning the entire bus, it can fill in this function and 280 * call scsi_scan_host(). This function will be called periodically 281 * until it returns 1 with the scsi_host and the elapsed time of 282 * the scan in jiffies. 283 * 284 * Status: OPTIONAL 285 */ 286 int (* scan_finished)(struct Scsi_Host *, unsigned long); 287 288 /* 289 * If the host wants to be called before the scan starts, but 290 * after the midlayer has set up ready for the scan, it can fill 291 * in this function. 292 */ 293 void (* scan_start)(struct Scsi_Host *); 294 295 /* 296 * fill in this function to allow the queue depth of this host 297 * to be changeable (on a per device basis). returns either 298 * the current queue depth setting (may be different from what 299 * was passed in) or an error. An error should only be 300 * returned if the requested depth is legal but the driver was 301 * unable to set it. If the requested depth is illegal, the 302 * driver should set and return the closest legal queue depth. 303 * 304 */ 305 int (* change_queue_depth)(struct scsi_device *, int); 306 307 /* 308 * fill in this function to allow the changing of tag types 309 * (this also allows the enabling/disabling of tag command 310 * queueing). An error should only be returned if something 311 * went wrong in the driver while trying to set the tag type. 312 * If the driver doesn't support the requested tag type, then 313 * it should set the closest type it does support without 314 * returning an error. Returns the actual tag type set. 315 */ 316 int (* change_queue_type)(struct scsi_device *, int); 317 318 /* 319 * This function determines the bios parameters for a given 320 * harddisk. These tend to be numbers that are made up by 321 * the host adapter. Parameters: 322 * size, device, list (heads, sectors, cylinders) 323 * 324 * Status: OPTIONAL */ 325 int (* bios_param)(struct scsi_device *, struct block_device *, 326 sector_t, int []); 327 328 /* 329 * Can be used to export driver statistics and other infos to the 330 * world outside the kernel ie. userspace and it also provides an 331 * interface to feed the driver with information. 332 * 333 * Status: OBSOLETE 334 */ 335 int (*proc_info)(struct Scsi_Host *, char *, char **, off_t, int, int); 336 337 /* 338 * suspend support 339 */ 340 int (*resume)(struct scsi_device *); 341 int (*suspend)(struct scsi_device *, pm_message_t state); 342 343 /* 344 * Name of proc directory 345 */ 346 char *proc_name; 347 348 /* 349 * Used to store the procfs directory if a driver implements the 350 * proc_info method. 351 */ 352 struct proc_dir_entry *proc_dir; 353 354 /* 355 * This determines if we will use a non-interrupt driven 356 * or an interrupt driven scheme, It is set to the maximum number 357 * of simultaneous commands a given host adapter will accept. 358 */ 359 int can_queue; 360 361 /* 362 * In many instances, especially where disconnect / reconnect are 363 * supported, our host also has an ID on the SCSI bus. If this is 364 * the case, then it must be reserved. Please set this_id to -1 if 365 * your setup is in single initiator mode, and the host lacks an 366 * ID. 367 */ 368 int this_id; 369 370 /* 371 * This determines the degree to which the host adapter is capable 372 * of scatter-gather. 373 */ 374 unsigned short sg_tablesize; 375 376 /* 377 * If the host adapter has limitations beside segment count 378 */ 379 unsigned short max_sectors; 380 381 /* 382 * dma scatter gather segment boundary limit. a segment crossing this 383 * boundary will be split in two. 384 */ 385 unsigned long dma_boundary; 386 387 /* 388 * This specifies "machine infinity" for host templates which don't 389 * limit the transfer size. Note this limit represents an absolute 390 * maximum, and may be over the transfer limits allowed for 391 * individual devices (e.g. 256 for SCSI-1) 392 */ 393 #define SCSI_DEFAULT_MAX_SECTORS 1024 394 395 /* 396 * True if this host adapter can make good use of linked commands. 397 * This will allow more than one command to be queued to a given 398 * unit on a given host. Set this to the maximum number of command 399 * blocks to be provided for each device. Set this to 1 for one 400 * command block per lun, 2 for two, etc. Do not set this to 0. 401 * You should make sure that the host adapter will do the right thing 402 * before you try setting this above 1. 403 */ 404 short cmd_per_lun; 405 406 /* 407 * present contains counter indicating how many boards of this 408 * type were found when we did the scan. 409 */ 410 unsigned char present; 411 412 /* 413 * true if this host adapter uses unchecked DMA onto an ISA bus. 414 */ 415 unsigned unchecked_isa_dma:1; 416 417 /* 418 * true if this host adapter can make good use of clustering. 419 * I originally thought that if the tablesize was large that it 420 * was a waste of CPU cycles to prepare a cluster list, but 421 * it works out that the Buslogic is faster if you use a smaller 422 * number of segments (i.e. use clustering). I guess it is 423 * inefficient. 424 */ 425 unsigned use_clustering:1; 426 427 /* 428 * True for emulated SCSI host adapters (e.g. ATAPI) 429 */ 430 unsigned emulated:1; 431 432 /* 433 * True if the low-level driver performs its own reset-settle delays. 434 */ 435 unsigned skip_settle_delay:1; 436 437 /* 438 * ordered write support 439 */ 440 unsigned ordered_tag:1; 441 442 /* 443 * Countdown for host blocking with no commands outstanding 444 */ 445 unsigned int max_host_blocked; 446 447 /* 448 * Default value for the blocking. If the queue is empty, 449 * host_blocked counts down in the request_fn until it restarts 450 * host operations as zero is reached. 451 * 452 * FIXME: This should probably be a value in the template 453 */ 454 #define SCSI_DEFAULT_HOST_BLOCKED 7 455 456 /* 457 * Pointer to the sysfs class properties for this host, NULL terminated. 458 */ 459 struct class_device_attribute **shost_attrs; 460 461 /* 462 * Pointer to the SCSI device properties for this host, NULL terminated. 463 */ 464 struct device_attribute **sdev_attrs; 465 466 /* 467 * List of hosts per template. 468 * 469 * This is only for use by scsi_module.c for legacy templates. 470 * For these access to it is synchronized implicitly by 471 * module_init/module_exit. 472 */ 473 struct list_head legacy_hosts; 474 }; 475 476 /* 477 * shost state: If you alter this, you also need to alter scsi_sysfs.c 478 * (for the ascii descriptions) and the state model enforcer: 479 * scsi_host_set_state() 480 */ 481 enum scsi_host_state { 482 SHOST_CREATED = 1, 483 SHOST_RUNNING, 484 SHOST_CANCEL, 485 SHOST_DEL, 486 SHOST_RECOVERY, 487 SHOST_CANCEL_RECOVERY, 488 SHOST_DEL_RECOVERY, 489 }; 490 491 struct Scsi_Host { 492 /* 493 * __devices is protected by the host_lock, but you should 494 * usually use scsi_device_lookup / shost_for_each_device 495 * to access it and don't care about locking yourself. 496 * In the rare case of beeing in irq context you can use 497 * their __ prefixed variants with the lock held. NEVER 498 * access this list directly from a driver. 499 */ 500 struct list_head __devices; 501 struct list_head __targets; 502 503 struct scsi_host_cmd_pool *cmd_pool; 504 spinlock_t free_list_lock; 505 struct list_head free_list; /* backup store of cmd structs */ 506 struct list_head starved_list; 507 508 spinlock_t default_lock; 509 spinlock_t *host_lock; 510 511 struct mutex scan_mutex;/* serialize scanning activity */ 512 513 struct list_head eh_cmd_q; 514 struct task_struct * ehandler; /* Error recovery thread. */ 515 struct completion * eh_action; /* Wait for specific actions on the 516 host. */ 517 wait_queue_head_t host_wait; 518 struct scsi_host_template *hostt; 519 struct scsi_transport_template *transportt; 520 521 /* 522 * area to keep a shared tag map (if needed, will be 523 * NULL if not) 524 */ 525 struct blk_queue_tag *bqt; 526 527 /* 528 * The following two fields are protected with host_lock; 529 * however, eh routines can safely access during eh processing 530 * without acquiring the lock. 531 */ 532 unsigned int host_busy; /* commands actually active on low-level */ 533 unsigned int host_failed; /* commands that failed. */ 534 unsigned int host_eh_scheduled; /* EH scheduled without command */ 535 536 unsigned short host_no; /* Used for IOCTL_GET_IDLUN, /proc/scsi et al. */ 537 int resetting; /* if set, it means that last_reset is a valid value */ 538 unsigned long last_reset; 539 540 /* 541 * These three parameters can be used to allow for wide scsi, 542 * and for host adapters that support multiple busses 543 * The first two should be set to 1 more than the actual max id 544 * or lun (i.e. 8 for normal systems). 545 */ 546 unsigned int max_id; 547 unsigned int max_lun; 548 unsigned int max_channel; 549 550 /* 551 * This is a unique identifier that must be assigned so that we 552 * have some way of identifying each detected host adapter properly 553 * and uniquely. For hosts that do not support more than one card 554 * in the system at one time, this does not need to be set. It is 555 * initialized to 0 in scsi_register. 556 */ 557 unsigned int unique_id; 558 559 /* 560 * The maximum length of SCSI commands that this host can accept. 561 * Probably 12 for most host adapters, but could be 16 for others. 562 * For drivers that don't set this field, a value of 12 is 563 * assumed. I am leaving this as a number rather than a bit 564 * because you never know what subsequent SCSI standards might do 565 * (i.e. could there be a 20 byte or a 24-byte command a few years 566 * down the road?). 567 */ 568 unsigned char max_cmd_len; 569 570 int this_id; 571 int can_queue; 572 short cmd_per_lun; 573 short unsigned int sg_tablesize; 574 short unsigned int max_sectors; 575 unsigned long dma_boundary; 576 /* 577 * Used to assign serial numbers to the cmds. 578 * Protected by the host lock. 579 */ 580 unsigned long cmd_serial_number, cmd_pid; 581 582 unsigned unchecked_isa_dma:1; 583 unsigned use_clustering:1; 584 unsigned use_blk_tcq:1; 585 586 /* 587 * Host has requested that no further requests come through for the 588 * time being. 589 */ 590 unsigned host_self_blocked:1; 591 592 /* 593 * Host uses correct SCSI ordering not PC ordering. The bit is 594 * set for the minority of drivers whose authors actually read 595 * the spec ;) 596 */ 597 unsigned reverse_ordering:1; 598 599 /* 600 * ordered write support 601 */ 602 unsigned ordered_tag:1; 603 604 /* task mgmt function in progress */ 605 unsigned tmf_in_progress:1; 606 607 /* Asynchronous scan in progress */ 608 unsigned async_scan:1; 609 610 /* 611 * Optional work queue to be utilized by the transport 612 */ 613 char work_q_name[KOBJ_NAME_LEN]; 614 struct workqueue_struct *work_q; 615 616 /* 617 * Host has rejected a command because it was busy. 618 */ 619 unsigned int host_blocked; 620 621 /* 622 * Value host_blocked counts down from 623 */ 624 unsigned int max_host_blocked; 625 626 /* 627 * q used for scsi_tgt msgs, async events or any other requests that 628 * need to be processed in userspace 629 */ 630 struct request_queue *uspace_req_q; 631 632 /* legacy crap */ 633 unsigned long base; 634 unsigned long io_port; 635 unsigned char n_io_port; 636 unsigned char dma_channel; 637 unsigned int irq; 638 639 640 enum scsi_host_state shost_state; 641 642 /* ldm bits */ 643 struct device shost_gendev; 644 struct class_device shost_classdev; 645 646 /* 647 * List of hosts per template. 648 * 649 * This is only for use by scsi_module.c for legacy templates. 650 * For these access to it is synchronized implicitly by 651 * module_init/module_exit. 652 */ 653 struct list_head sht_legacy_list; 654 655 /* 656 * Points to the transport data (if any) which is allocated 657 * separately 658 */ 659 void *shost_data; 660 661 /* 662 * We should ensure that this is aligned, both for better performance 663 * and also because some compilers (m68k) don't automatically force 664 * alignment to a long boundary. 665 */ 666 unsigned long hostdata[0] /* Used for storage of host specific stuff */ 667 __attribute__ ((aligned (sizeof(unsigned long)))); 668 }; 669 670 #define class_to_shost(d) \ 671 container_of(d, struct Scsi_Host, shost_classdev) 672 673 #define shost_printk(prefix, shost, fmt, a...) \ 674 dev_printk(prefix, &(shost)->shost_gendev, fmt, ##a) 675 676 677 int scsi_is_host_device(const struct device *); 678 679 static inline struct Scsi_Host *dev_to_shost(struct device *dev) 680 { 681 while (!scsi_is_host_device(dev)) { 682 if (!dev->parent) 683 return NULL; 684 dev = dev->parent; 685 } 686 return container_of(dev, struct Scsi_Host, shost_gendev); 687 } 688 689 static inline int scsi_host_in_recovery(struct Scsi_Host *shost) 690 { 691 return shost->shost_state == SHOST_RECOVERY || 692 shost->shost_state == SHOST_CANCEL_RECOVERY || 693 shost->shost_state == SHOST_DEL_RECOVERY || 694 shost->tmf_in_progress; 695 } 696 697 extern int scsi_queue_work(struct Scsi_Host *, struct work_struct *); 698 extern void scsi_flush_work(struct Scsi_Host *); 699 700 extern struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *, int); 701 extern int __must_check scsi_add_host(struct Scsi_Host *, struct device *); 702 extern void scsi_scan_host(struct Scsi_Host *); 703 extern void scsi_rescan_device(struct device *); 704 extern void scsi_remove_host(struct Scsi_Host *); 705 extern struct Scsi_Host *scsi_host_get(struct Scsi_Host *); 706 extern void scsi_host_put(struct Scsi_Host *t); 707 extern struct Scsi_Host *scsi_host_lookup(unsigned short); 708 extern const char *scsi_host_state_name(enum scsi_host_state); 709 710 extern u64 scsi_calculate_bounce_limit(struct Scsi_Host *); 711 712 static inline struct device *scsi_get_device(struct Scsi_Host *shost) 713 { 714 return shost->shost_gendev.parent; 715 } 716 717 /** 718 * scsi_host_scan_allowed - Is scanning of this host allowed 719 * @shost: Pointer to Scsi_Host. 720 **/ 721 static inline int scsi_host_scan_allowed(struct Scsi_Host *shost) 722 { 723 return shost->shost_state == SHOST_RUNNING; 724 } 725 726 extern void scsi_unblock_requests(struct Scsi_Host *); 727 extern void scsi_block_requests(struct Scsi_Host *); 728 729 struct class_container; 730 731 extern struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost, 732 void (*) (struct request_queue *)); 733 /* 734 * These two functions are used to allocate and free a pseudo device 735 * which will connect to the host adapter itself rather than any 736 * physical device. You must deallocate when you are done with the 737 * thing. This physical pseudo-device isn't real and won't be available 738 * from any high-level drivers. 739 */ 740 extern void scsi_free_host_dev(struct scsi_device *); 741 extern struct scsi_device *scsi_get_host_dev(struct Scsi_Host *); 742 743 /* legacy interfaces */ 744 extern struct Scsi_Host *scsi_register(struct scsi_host_template *, int); 745 extern void scsi_unregister(struct Scsi_Host *); 746 extern int scsi_host_set_state(struct Scsi_Host *, enum scsi_host_state); 747 748 #endif /* _SCSI_SCSI_HOST_H */ 749