include/scsi/sg.h

   1 #ifndef _SCSI_GENERIC_H
   2 #define _SCSI_GENERIC_H
   3
   4 #include <linux/compiler.h>
   5
   6 /*
   7    History:
   8     Started: Aug 9 by Lawrence Foard (entropy@world.std.com), to allow user
   9      process control of SCSI devices.
  10     Development Sponsored by Killy Corp. NY NY
  11 Original driver (sg.h):
  12 *       Copyright (C) 1992 Lawrence Foard
  13 Version 2 and 3 extensions to driver:
  14 *       Copyright (C) 1998 - 2006 Douglas Gilbert
  15
  16     Version: 3.5.34 (20060920)
  17     This version is for 2.6 series kernels.
  18
  19     For a full changelog see http://www.torque.net/sg
  20
  21 Map of SG verions to the Linux kernels in which they appear:
  22        ----------        ----------------------------------
  23        original          all kernels < 2.2.6
  24        2.1.40            2.2.20
  25        3.0.x             optional version 3 sg driver for 2.2 series
  26        3.1.17++          2.4.0++
  27        3.5.30++          2.6.0++
  28
  29 Major new features in SG 3.x driver (cf SG 2.x drivers)
  30         - SG_IO ioctl() combines function if write() and read()
  31         - new interface (sg_io_hdr_t) but still supports old interface
  32         - scatter/gather in user space, direct IO, and mmap supported
  33
  34  The normal action of this driver is to use the adapter (HBA) driver to DMA
  35  data into kernel buffers and then use the CPU to copy the data into the
  36  user space (vice versa for writes). That is called "indirect" IO due to
  37  the double handling of data. There are two methods offered to remove the
  38  redundant copy: 1) direct IO and 2) using the mmap() system call to map
  39  the reserve buffer (this driver has one reserve buffer per fd) into the
  40  user space. Both have their advantages.
  41  In terms of absolute speed mmap() is faster. If speed is not a concern,
  42  indirect IO should be fine. Read the documentation for more information.
  43
  44  ** N.B. To use direct IO 'echo 1 > /proc/scsi/sg/allow_dio' or
  45          'echo 1 > /sys/module/sg/parameters/allow_dio' is needed.
  46          That attribute is 0 by default. **
  47
  48  Historical note: this SCSI pass-through driver has been known as "sg" for
  49  a decade. In broader kernel discussions "sg" is used to refer to scatter
  50  gather techniques. The context should clarify which "sg" is referred to.
  51
  52  Documentation
  53  =============
  54  A web site for the SG device driver can be found at:
  55         http://www.torque.net/sg  [alternatively check the MAINTAINERS file]
  56  The documentation for the sg version 3 driver can be found at:
  57         http://www.torque.net/sg/p/sg_v3_ho.html
  58  This is a rendering from DocBook source [change the extension to "sgml"
  59  or "xml"]. There are renderings in "ps", "pdf", "rtf" and "txt" (soon).
  60  The SG_IO ioctl is now found in other parts kernel (e.g. the block layer).
  61  For more information see http://www.torque.net/sg/sg_io.html
  62
  63  The older, version 2 documents discuss the original sg interface in detail:
  64         http://www.torque.net/sg/p/scsi-generic.txt
  65         http://www.torque.net/sg/p/scsi-generic_long.txt
  66  Also available: <kernel_source>/Documentation/scsi/scsi-generic.txt
  67
  68  Utility and test programs are available at the sg web site. They are
  69  packaged as sg3_utils (for the lk 2.4 and 2.6 series) and sg_utils
  70  (for the lk 2.2 series).
  71 */
  72
  73
  74 /* New interface introduced in the 3.x SG drivers follows */
  75
  76 typedef struct sg_iovec /* same structure as used by readv() Linux system */
  77 {                       /* call. It defines one scatter-gather element. */
  78     void __user *iov_base;      /* Starting address  */
  79     size_t iov_len;             /* Length in bytes  */
  80 } sg_iovec_t;
  81
  82
  83 typedef struct sg_io_hdr
  84 {
  85     int interface_id;           /* [i] 'S' for SCSI generic (required) */
  86     int dxfer_direction;        /* [i] data transfer direction  */
  87     unsigned char cmd_len;      /* [i] SCSI command length ( <= 16 bytes) */
  88     unsigned char mx_sb_len;    /* [i] max length to write to sbp */
  89     unsigned short iovec_count; /* [i] 0 implies no scatter gather */
  90     unsigned int dxfer_len;     /* [i] byte count of data transfer */
  91     void __user *dxferp;        /* [i], [*io] points to data transfer memory
  92                                               or scatter gather list */
  93     unsigned char __user *cmdp; /* [i], [*i] points to command to perform */
  94     void __user *sbp;           /* [i], [*o] points to sense_buffer memory */
  95     unsigned int timeout;       /* [i] MAX_UINT->no timeout (unit: millisec) */
  96     unsigned int flags;         /* [i] 0 -> default, see SG_FLAG... */
  97     int pack_id;                /* [i->o] unused internally (normally) */
  98     void __user * usr_ptr;      /* [i->o] unused internally */
  99     unsigned char status;       /* [o] scsi status */
 100     unsigned char masked_status;/* [o] shifted, masked scsi status */
 101     unsigned char msg_status;   /* [o] messaging level data (optional) */
 102     unsigned char sb_len_wr;    /* [o] byte count actually written to sbp */
 103     unsigned short host_status; /* [o] errors from host adapter */
 104     unsigned short driver_status;/* [o] errors from software driver */
 105     int resid;                  /* [o] dxfer_len - actual_transferred */
 106     unsigned int duration;      /* [o] time taken by cmd (unit: millisec) */
 107     unsigned int info;          /* [o] auxiliary information */
 108 } sg_io_hdr_t;  /* 64 bytes long (on i386) */
 109
 110 #define SG_INTERFACE_ID_ORIG 'S'
 111
 112 /* Use negative values to flag difference from original sg_header structure */
 113 #define SG_DXFER_NONE (-1)      /* e.g. a SCSI Test Unit Ready command */
 114 #define SG_DXFER_TO_DEV (-2)    /* e.g. a SCSI WRITE command */
 115 #define SG_DXFER_FROM_DEV (-3)  /* e.g. a SCSI READ command */
 116 #define SG_DXFER_TO_FROM_DEV (-4) /* treated like SG_DXFER_FROM_DEV with the
 117                                    additional property than during indirect
 118                                    IO the user buffer is copied into the
 119                                    kernel buffers before the transfer */
 120 #define SG_DXFER_UNKNOWN (-5)   /* Unknown data direction */
 121
 122 /* following flag values can be "or"-ed together */
 123 #define SG_FLAG_DIRECT_IO 1     /* default is indirect IO */
 124 #define SG_FLAG_UNUSED_LUN_INHIBIT 2   /* default is overwrite lun in SCSI */
 125                                 /* command block (when <= SCSI_2) */
 126 #define SG_FLAG_MMAP_IO 4       /* request memory mapped IO */
 127 #define SG_FLAG_NO_DXFER 0x10000 /* no transfer of kernel buffers to/from */
 128                                 /* user space (debug indirect IO) */
 129
 130 /* following 'info' values are "or"-ed together */
 131 #define SG_INFO_OK_MASK 0x1
 132 #define SG_INFO_OK 0x0          /* no sense, host nor driver "noise" */
 133 #define SG_INFO_CHECK 0x1       /* something abnormal happened */
 134
 135 #define SG_INFO_DIRECT_IO_MASK 0x6
 136 #define SG_INFO_INDIRECT_IO 0x0 /* data xfer via kernel buffers (or no xfer) */
 137 #define SG_INFO_DIRECT_IO 0x2   /* direct IO requested and performed */
 138 #define SG_INFO_MIXED_IO 0x4    /* part direct, part indirect IO */
 139
 140
 141 typedef struct sg_scsi_id { /* used by SG_GET_SCSI_ID ioctl() */
 142     int host_no;        /* as in "scsi<n>" where 'n' is one of 0, 1, 2 etc */
 143     int channel;
 144     int scsi_id;        /* scsi id of target device */
 145     int lun;
 146     int scsi_type;      /* TYPE_... defined in scsi/scsi.h */
 147     short h_cmd_per_lun;/* host (adapter) maximum commands per lun */
 148     short d_queue_depth;/* device (or adapter) maximum queue length */
 149     int unused[2];      /* probably find a good use, set 0 for now */
 150 } sg_scsi_id_t; /* 32 bytes long on i386 */
 151
 152 typedef struct sg_req_info { /* used by SG_GET_REQUEST_TABLE ioctl() */
 153     char req_state;     /* 0 -> not used, 1 -> written, 2 -> ready to read */
 154     char orphan;        /* 0 -> normal request, 1 -> from interruped SG_IO */
 155     char sg_io_owned;   /* 0 -> complete with read(), 1 -> owned by SG_IO */
 156     char problem;       /* 0 -> no problem detected, 1 -> error to report */
 157     int pack_id;        /* pack_id associated with request */
 158     void __user *usr_ptr;     /* user provided pointer (in new interface) */
 159     unsigned int duration; /* millisecs elapsed since written (req_state==1)
 160                               or request duration (req_state==2) */
 161     int unused;
 162 } sg_req_info_t; /* 20 bytes long on i386 */
 163
 164
 165 /* IOCTLs: Those ioctls that are relevant to the SG 3.x drivers follow.
 166  [Those that only apply to the SG 2.x drivers are at the end of the file.]
 167  (_GET_s yield result via 'int *' 3rd argument unless otherwise indicated) */
 168
 169 #define SG_EMULATED_HOST 0x2203 /* true for emulated host adapter (ATAPI) */
 170
 171 /* Used to configure SCSI command transformation layer for ATAPI devices */
 172 /* Only supported by the ide-scsi driver */
 173 #define SG_SET_TRANSFORM 0x2204 /* N.B. 3rd arg is not pointer but value: */
 174                       /* 3rd arg = 0 to disable transform, 1 to enable it */
 175 #define SG_GET_TRANSFORM 0x2205
 176
 177 #define SG_SET_RESERVED_SIZE 0x2275  /* request a new reserved buffer size */
 178 #define SG_GET_RESERVED_SIZE 0x2272  /* actual size of reserved buffer */
 179
 180 /* The following ioctl has a 'sg_scsi_id_t *' object as its 3rd argument. */
 181 #define SG_GET_SCSI_ID 0x2276   /* Yields fd's bus, chan, dev, lun + type */
 182 /* SCSI id information can also be obtained from SCSI_IOCTL_GET_IDLUN */
 183
 184 /* Override host setting and always DMA using low memory ( <16MB on i386) */
 185 #define SG_SET_FORCE_LOW_DMA 0x2279  /* 0-> use adapter setting, 1-> force */
 186 #define SG_GET_LOW_DMA 0x227a   /* 0-> use all ram for dma; 1-> low dma ram */
 187
 188 /* When SG_SET_FORCE_PACK_ID set to 1, pack_id is input to read() which
 189    tries to fetch a packet with a matching pack_id, waits, or returns EAGAIN.
 190    If pack_id is -1 then read oldest waiting. When ...FORCE_PACK_ID set to 0
 191    then pack_id ignored by read() and oldest readable fetched. */
 192 #define SG_SET_FORCE_PACK_ID 0x227b
 193 #define SG_GET_PACK_ID 0x227c /* Yields oldest readable pack_id (or -1) */
 194
 195 #define SG_GET_NUM_WAITING 0x227d /* Number of commands awaiting read() */
 196
 197 /* Yields max scatter gather tablesize allowed by current host adapter */
 198 #define SG_GET_SG_TABLESIZE 0x227F  /* 0 implies can't do scatter gather */
 199
 200 #define SG_GET_VERSION_NUM 0x2282 /* Example: version 2.1.34 yields 20134 */
 201
 202 /* Returns -EBUSY if occupied. 3rd argument pointer to int (see next) */
 203 #define SG_SCSI_RESET 0x2284
 204 /* Associated values that can be given to SG_SCSI_RESET follow */
 205 #define         SG_SCSI_RESET_NOTHING   0
 206 #define         SG_SCSI_RESET_DEVICE    1
 207 #define         SG_SCSI_RESET_BUS       2
 208 #define         SG_SCSI_RESET_HOST      3
 209
 210 /* synchronous SCSI command ioctl, (only in version 3 interface) */
 211 #define SG_IO 0x2285   /* similar effect as write() followed by read() */
 212
 213 #define SG_GET_REQUEST_TABLE 0x2286   /* yields table of active requests */
 214
 215 /* How to treat EINTR during SG_IO ioctl(), only in SG 3.x series */
 216 #define SG_SET_KEEP_ORPHAN 0x2287 /* 1 -> hold for read(), 0 -> drop (def) */
 217 #define SG_GET_KEEP_ORPHAN 0x2288
 218
 219 /* yields scsi midlevel's access_count for this SCSI device */
 220 #define SG_GET_ACCESS_COUNT 0x2289
 221
 222
 223 #define SG_SCATTER_SZ (8 * 4096)
 224 /* Largest size (in bytes) a single scatter-gather list element can have.
 225    The value used by the driver is 'max(SG_SCATTER_SZ, PAGE_SIZE)'.
 226    This value should be a power of 2 (and may be rounded up internally).
 227    If scatter-gather is not supported by adapter then this value is the
 228    largest data block that can be read/written by a single scsi command. */
 229
 230 #define SG_DEFAULT_RETRIES 0
 231
 232 /* Defaults, commented if they differ from original sg driver */
 233 #define SG_DEF_FORCE_LOW_DMA 0  /* was 1 -> memory below 16MB on i386 */
 234 #define SG_DEF_FORCE_PACK_ID 0
 235 #define SG_DEF_KEEP_ORPHAN 0
 236 #define SG_DEF_RESERVED_SIZE SG_SCATTER_SZ /* load time option */
 237
 238 /* maximum outstanding requests, write() yields EDOM if exceeded */
 239 #define SG_MAX_QUEUE 16
 240
 241 #define SG_BIG_BUFF SG_DEF_RESERVED_SIZE    /* for backward compatibility */
 242
 243 /* Alternate style type names, "..._t" variants preferred */
 244 typedef struct sg_io_hdr Sg_io_hdr;
 245 typedef struct sg_io_vec Sg_io_vec;
 246 typedef struct sg_scsi_id Sg_scsi_id;
 247 typedef struct sg_req_info Sg_req_info;
 248
 249
 250 /* vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv */
 251 /*   The older SG interface based on the 'sg_header' structure follows.   */
 252 /* ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ */
 253
 254 #define SG_MAX_SENSE 16   /* this only applies to the sg_header interface */
 255
 256 struct sg_header
 257 {
 258     int pack_len;    /* [o] reply_len (ie useless), ignored as input */
 259     int reply_len;   /* [i] max length of expected reply (inc. sg_header) */
 260     int pack_id;     /* [io] id number of packet (use ints >= 0) */
 261     int result;      /* [o] 0==ok, else (+ve) Unix errno (best ignored) */
 262     unsigned int twelve_byte:1;
 263         /* [i] Force 12 byte command length for group 6 & 7 commands  */
 264     unsigned int target_status:5;   /* [o] scsi status from target */
 265     unsigned int host_status:8;     /* [o] host status (see "DID" codes) */
 266     unsigned int driver_status:8;   /* [o] driver status+suggestion */
 267     unsigned int other_flags:10;    /* unused */
 268     unsigned char sense_buffer[SG_MAX_SENSE]; /* [o] Output in 3 cases:
 269            when target_status is CHECK_CONDITION or
 270            when target_status is COMMAND_TERMINATED or
 271            when (driver_status & DRIVER_SENSE) is true. */
 272 };      /* This structure is 36 bytes long on i386 */
 273
 274
 275 /* IOCTLs: The following are not required (or ignored) when the sg_io_hdr_t
 276            interface is used. They are kept for backward compatibility with
 277            the original and version 2 drivers. */
 278
 279 #define SG_SET_TIMEOUT 0x2201  /* unit: jiffies (10ms on i386) */
 280 #define SG_GET_TIMEOUT 0x2202  /* yield timeout as _return_ value */
 281
 282 /* Get/set command queuing state per fd (default is SG_DEF_COMMAND_Q.
 283    Each time a sg_io_hdr_t object is seen on this file descriptor, this
 284    command queuing flag is set on (overriding the previous setting). */
 285 #define SG_GET_COMMAND_Q 0x2270   /* Yields 0 (queuing off) or 1 (on) */
 286 #define SG_SET_COMMAND_Q 0x2271   /* Change queuing state with 0 or 1 */
 287
 288 /* Turn on/off error sense trace (1 and 0 respectively, default is off).
 289    Try using: "# cat /proc/scsi/sg/debug" instead in the v3 driver */
 290 #define SG_SET_DEBUG 0x227e    /* 0 -> turn off debug */
 291
 292 #define SG_NEXT_CMD_LEN 0x2283  /* override SCSI command length with given
 293                    number on the next write() on this file descriptor */
 294
 295
 296 /* Defaults, commented if they differ from original sg driver */
 297 #ifdef __KERNEL__
 298 #define SG_DEFAULT_TIMEOUT_USER (60*USER_HZ) /* HZ == 'jiffies in 1 second' */
 299 #else
 300 #define SG_DEFAULT_TIMEOUT      (60*HZ)      /* HZ == 'jiffies in 1 second' */
 301 #endif
 302
 303 #define SG_DEF_COMMAND_Q 0     /* command queuing is always on when
 304                                   the new interface is used */
 305 #define SG_DEF_UNDERRUN_FLAG 0
 306
 307 #endif