include/scsi/scsi_host.h

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  49          * Status:  OBSOLETE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  56          * Status: OBSOLETE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