1 #ifndef _SCSI_GENERIC_H 2 #define _SCSI_GENERIC_H 3 4 /* 5 History: 6 Started: Aug 9 by Lawrence Foard (entropy@world.std.com), to allow user 7 process control of SCSI devices. 8 Development Sponsored by Killy Corp. NY NY 9 Original driver (sg.h): 10 * Copyright (C) 1992 Lawrence Foard 11 Version 2 and 3 extensions to driver: 12 * Copyright (C) 1998 - 2003 Douglas Gilbert 13 14 Version: 3.1.25 (20030529) 15 This version is for 2.4 series kernels. 16 17 Changes since 3.1.24 (20020505) 18 - fix side effect introduced by last "off by one" fix 19 Changes since 3.1.23 (20020318) 20 - off by one fix for last scatter gather element 21 - zero buffer obtained for non-root users 22 Changes since 3.1.22 (20011208) 23 - change EACCES to EPERM when O_RDONLY is insufficient 24 - suppress newlines in host string ( /proc/scsi/sg/host_strs output) 25 - fix xfer direction, old interface, short reply_len [Travers Carter] 26 Changes since 3.1.21 (20011029) 27 - add support for SG_FLAG_MMAP_IO [permit mmap() on sg devices] 28 - update documentation pointers in this header 29 - put KERNEL_VERSION macros around code that breaks early 2.4 series 30 - fix use count for multiple queued requests on closed fd 31 - switch back to alloc_kiovec() 32 Changes since 3.1.20 (20010814) 33 - use alloc_kiovec_sz() to speed dio [set num_buffer_heads==0] 34 - changes to cope with larger scatter gather element sizes 35 - clean up some printk()s 36 - add MODULE_LICENSE("GPL") [in a 3.1.20 subversion] 37 - fix race around generic_unplug_device() [in a 3.1.20 subversion] 38 Changes since 3.1.19 (20010623) 39 - add SG_GET_ACCESS_COUNT ioctl 40 - make open() increment and close() decrement access_count 41 - only register first 256 devices, reject subsequent devices 42 Changes since 3.1.18 (20010505) 43 - fix bug that caused long wait when large buffer requested 44 - fix leak in error case of sg_new_read() [report: Eric Barton] 45 - add 'online' column to /proc/scsi/sg/devices 46 Changes since 3.1.17 (20000921) 47 - add CAP_SYS_RAWIO capability for sensitive stuff 48 - compile in dio stuff, procfs 'allow_dio' defaulted off (0) 49 - make premature close and detach more robust 50 - lun masked into commands <= SCSI_2 51 - poll() and async notification now yield POLL_HUP on detach 52 - various 3rd party tweaks tracking lk 2.4 internal changes 53 54 Map of SG verions to the Linux kernels in which they appear: 55 ---------- ---------------------------------- 56 original all kernels < 2.2.6 57 2.1.40 2.2.20 58 3.0.x optional version 3 sg driver for 2.2 series 59 3.1.17++ 2.4.0++ 60 61 Major new features in SG 3.x driver (cf SG 2.x drivers) 62 - SG_IO ioctl() combines function if write() and read() 63 - new interface (sg_io_hdr_t) but still supports old interface 64 - scatter/gather in user space, direct IO, and mmap supported 65 66 The normal action of this driver is to use the adapter (HBA) driver to DMA 67 data into kernel buffers and then use the CPU to copy the data into the 68 user space (vice versa for writes). That is called "indirect" IO due to 69 the double handling of data. There are two methods offered to remove the 70 redundant copy: 1) direct IO which uses the kernel kiobuf mechanism and 71 2) using the mmap() system call to map the reserve buffer (this driver has 72 one reserve buffer per fd) into the user space. Both have their advantages. 73 In terms of absolute speed mmap() is faster. If speed is not a concern, 74 indirect IO should be fine. Read the documentation for more information. 75 76 ** N.B. To use direct IO 'echo 1 > /proc/scsi/sg/allow_dio' may be 77 needed. That pseudo file's content is defaulted to 0. ** 78 79 Historical note: this SCSI pass-through driver has been known as "sg" for 80 a decade. In broader kernel discussions "sg" is used to refer to scatter 81 gather techniques. The context should clarify which "sg" is referred to. 82 83 Documentation 84 ============= 85 A web site for the SG device driver can be found at: 86 http://www.torque.net/sg [alternatively check the MAINTAINERS file] 87 The documentation for the sg version 3 driver can be found at: 88 http://www.torque.net/sg/p/sg_v3_ho.html 89 This is a rendering from DocBook source [change the extension to "sgml" 90 or "xml"]. There are renderings in "ps", "pdf", "rtf" and "txt" (soon). 91 92 The older, version 2 documents discuss the original sg interface in detail: 93 http://www.torque.net/sg/p/scsi-generic.txt 94 http://www.torque.net/sg/p/scsi-generic_long.txt 95 A version of this document (potentially out of date) may also be found in 96 the kernel source tree, probably at: 97 /usr/src/linux/Documentation/scsi-generic.txt . 98 99 Utility and test programs are available at the sg web site. They are 100 bundled as sg_utils (for the lk 2.2 series) and sg3_utils (for the 101 lk 2.4 series). 102 103 There is a HOWTO on the Linux SCSI subsystem in the lk 2.4 series at: 104 http://www.linuxdoc.org/HOWTO/SCSI-2.4-HOWTO 105 */ 106 107 108 /* New interface introduced in the 3.x SG drivers follows */ 109 110 typedef struct sg_iovec /* same structure as used by readv() Linux system */ 111 { /* call. It defines one scatter-gather element. */ 112 void * iov_base; /* Starting address */ 113 size_t iov_len; /* Length in bytes */ 114 } sg_iovec_t; 115 116 117 typedef struct sg_io_hdr 118 { 119 int interface_id; /* [i] 'S' for SCSI generic (required) */ 120 int dxfer_direction; /* [i] data transfer direction */ 121 unsigned char cmd_len; /* [i] SCSI command length ( <= 16 bytes) */ 122 unsigned char mx_sb_len; /* [i] max length to write to sbp */ 123 unsigned short iovec_count; /* [i] 0 implies no scatter gather */ 124 unsigned int dxfer_len; /* [i] byte count of data transfer */ 125 void * dxferp; /* [i], [*io] points to data transfer memory 126 or scatter gather list */ 127 unsigned char * cmdp; /* [i], [*i] points to command to perform */ 128 unsigned char * sbp; /* [i], [*o] points to sense_buffer memory */ 129 unsigned int timeout; /* [i] MAX_UINT->no timeout (unit: millisec) */ 130 unsigned int flags; /* [i] 0 -> default, see SG_FLAG... */ 131 int pack_id; /* [i->o] unused internally (normally) */ 132 void * usr_ptr; /* [i->o] unused internally */ 133 unsigned char status; /* [o] scsi status */ 134 unsigned char masked_status;/* [o] shifted, masked scsi status */ 135 unsigned char msg_status; /* [o] messaging level data (optional) */ 136 unsigned char sb_len_wr; /* [o] byte count actually written to sbp */ 137 unsigned short host_status; /* [o] errors from host adapter */ 138 unsigned short driver_status;/* [o] errors from software driver */ 139 int resid; /* [o] dxfer_len - actual_transferred */ 140 unsigned int duration; /* [o] time taken by cmd (unit: millisec) */ 141 unsigned int info; /* [o] auxiliary information */ 142 } sg_io_hdr_t; /* 64 bytes long (on i386) */ 143 144 /* Use negative values to flag difference from original sg_header structure */ 145 #define SG_DXFER_NONE (-1) /* e.g. a SCSI Test Unit Ready command */ 146 #define SG_DXFER_TO_DEV (-2) /* e.g. a SCSI WRITE command */ 147 #define SG_DXFER_FROM_DEV (-3) /* e.g. a SCSI READ command */ 148 #define SG_DXFER_TO_FROM_DEV (-4) /* treated like SG_DXFER_FROM_DEV with the 149 additional property than during indirect 150 IO the user buffer is copied into the 151 kernel buffers before the transfer */ 152 #define SG_DXFER_UNKNOWN (-5) /* Unknown data direction */ 153 154 /* following flag values can be "or"-ed together */ 155 #define SG_FLAG_DIRECT_IO 1 /* default is indirect IO */ 156 #define SG_FLAG_LUN_INHIBIT 2 /* default is overwrite lun in SCSI */ 157 /* command block (when <= SCSI_2) */ 158 #define SG_FLAG_MMAP_IO 4 /* request memory mapped IO */ 159 #define SG_FLAG_NO_DXFER 0x10000 /* no transfer of kernel buffers to/from */ 160 /* user space (debug indirect IO) */ 161 162 /* following 'info' values are "or"-ed together */ 163 #define SG_INFO_OK_MASK 0x1 164 #define SG_INFO_OK 0x0 /* no sense, host nor driver "noise" */ 165 #define SG_INFO_CHECK 0x1 /* something abnormal happened */ 166 167 #define SG_INFO_DIRECT_IO_MASK 0x6 168 #define SG_INFO_INDIRECT_IO 0x0 /* data xfer via kernel buffers (or no xfer) */ 169 #define SG_INFO_DIRECT_IO 0x2 /* direct IO requested and performed */ 170 #define SG_INFO_MIXED_IO 0x4 /* part direct, part indirect IO */ 171 172 173 typedef struct sg_scsi_id { /* used by SG_GET_SCSI_ID ioctl() */ 174 int host_no; /* as in "scsi<n>" where 'n' is one of 0, 1, 2 etc */ 175 int channel; 176 int scsi_id; /* scsi id of target device */ 177 int lun; 178 int scsi_type; /* TYPE_... defined in scsi/scsi.h */ 179 short h_cmd_per_lun;/* host (adapter) maximum commands per lun */ 180 short d_queue_depth;/* device (or adapter) maximum queue length */ 181 int unused[2]; /* probably find a good use, set 0 for now */ 182 } sg_scsi_id_t; /* 32 bytes long on i386 */ 183 184 typedef struct sg_req_info { /* used by SG_GET_REQUEST_TABLE ioctl() */ 185 char req_state; /* 0 -> not used, 1 -> written, 2 -> ready to read */ 186 char orphan; /* 0 -> normal request, 1 -> from interruped SG_IO */ 187 char sg_io_owned; /* 0 -> complete with read(), 1 -> owned by SG_IO */ 188 char problem; /* 0 -> no problem detected, 1 -> error to report */ 189 int pack_id; /* pack_id associated with request */ 190 void * usr_ptr; /* user provided pointer (in new interface) */ 191 unsigned int duration; /* millisecs elapsed since written (req_state==1) 192 or request duration (req_state==2) */ 193 int unused; 194 } sg_req_info_t; /* 20 bytes long on i386 */ 195 196 197 /* IOCTLs: Those ioctls that are relevant to the SG 3.x drivers follow. 198 [Those that only apply to the SG 2.x drivers are at the end of the file.] 199 (_GET_s yield result via 'int *' 3rd argument unless otherwise indicated) */ 200 201 #define SG_EMULATED_HOST 0x2203 /* true for emulated host adapter (ATAPI) */ 202 203 /* Used to configure SCSI command transformation layer for ATAPI devices */ 204 /* Only supported by the ide-scsi driver */ 205 #define SG_SET_TRANSFORM 0x2204 /* N.B. 3rd arg is not pointer but value: */ 206 /* 3rd arg = 0 to disable transform, 1 to enable it */ 207 #define SG_GET_TRANSFORM 0x2205 208 209 #define SG_SET_RESERVED_SIZE 0x2275 /* request a new reserved buffer size */ 210 #define SG_GET_RESERVED_SIZE 0x2272 /* actual size of reserved buffer */ 211 212 /* The following ioctl has a 'sg_scsi_id_t *' object as its 3rd argument. */ 213 #define SG_GET_SCSI_ID 0x2276 /* Yields fd's bus, chan, dev, lun + type */ 214 /* SCSI id information can also be obtained from SCSI_IOCTL_GET_IDLUN */ 215 216 /* Override host setting and always DMA using low memory ( <16MB on i386) */ 217 #define SG_SET_FORCE_LOW_DMA 0x2279 /* 0-> use adapter setting, 1-> force */ 218 #define SG_GET_LOW_DMA 0x227a /* 0-> use all ram for dma; 1-> low dma ram */ 219 220 /* When SG_SET_FORCE_PACK_ID set to 1, pack_id is input to read() which 221 tries to fetch a packet with a matching pack_id, waits, or returns EAGAIN. 222 If pack_id is -1 then read oldest waiting. When ...FORCE_PACK_ID set to 0 223 then pack_id ignored by read() and oldest readable fetched. */ 224 #define SG_SET_FORCE_PACK_ID 0x227b 225 #define SG_GET_PACK_ID 0x227c /* Yields oldest readable pack_id (or -1) */ 226 227 #define SG_GET_NUM_WAITING 0x227d /* Number of commands awaiting read() */ 228 229 /* Yields max scatter gather tablesize allowed by current host adapter */ 230 #define SG_GET_SG_TABLESIZE 0x227F /* 0 implies can't do scatter gather */ 231 232 #define SG_GET_VERSION_NUM 0x2282 /* Example: version 2.1.34 yields 20134 */ 233 234 /* Returns -EBUSY if occupied. 3rd argument pointer to int (see next) */ 235 #define SG_SCSI_RESET 0x2284 236 /* Associated values that can be given to SG_SCSI_RESET follow */ 237 #define SG_SCSI_RESET_NOTHING 0 238 #define SG_SCSI_RESET_DEVICE 1 239 #define SG_SCSI_RESET_BUS 2 240 #define SG_SCSI_RESET_HOST 3 241 242 /* synchronous SCSI command ioctl, (only in version 3 interface) */ 243 #define SG_IO 0x2285 /* similar effect as write() followed by read() */ 244 245 #define SG_GET_REQUEST_TABLE 0x2286 /* yields table of active requests */ 246 247 /* How to treat EINTR during SG_IO ioctl(), only in SG 3.x series */ 248 #define SG_SET_KEEP_ORPHAN 0x2287 /* 1 -> hold for read(), 0 -> drop (def) */ 249 #define SG_GET_KEEP_ORPHAN 0x2288 250 251 /* yields scsi midlevel's access_count for this SCSI device */ 252 #define SG_GET_ACCESS_COUNT 0x2289 253 254 255 #define SG_SCATTER_SZ (8 * 4096) /* PAGE_SIZE not available to user */ 256 /* Largest size (in bytes) a single scatter-gather list element can have. 257 The value must be a power of 2 and <= (PAGE_SIZE * 32) [131072 bytes on 258 i386]. The minimum value is PAGE_SIZE. If scatter-gather not supported 259 by adapter then this value is the largest data block that can be 260 read/written by a single scsi command. The user can find the value of 261 PAGE_SIZE by calling getpagesize() defined in unistd.h . */ 262 263 #define SG_DEFAULT_RETRIES 1 264 265 /* Defaults, commented if they differ from original sg driver */ 266 #define SG_DEF_FORCE_LOW_DMA 0 /* was 1 -> memory below 16MB on i386 */ 267 #define SG_DEF_FORCE_PACK_ID 0 268 #define SG_DEF_KEEP_ORPHAN 0 269 #define SG_DEF_RESERVED_SIZE SG_SCATTER_SZ /* load time option */ 270 271 /* maximum outstanding requests, write() yields EDOM if exceeded */ 272 #define SG_MAX_QUEUE 16 273 274 #define SG_BIG_BUFF SG_DEF_RESERVED_SIZE /* for backward compatibility */ 275 276 /* Alternate style type names, "..._t" variants preferred */ 277 typedef struct sg_io_hdr Sg_io_hdr; 278 typedef struct sg_io_vec Sg_io_vec; 279 typedef struct sg_scsi_id Sg_scsi_id; 280 typedef struct sg_req_info Sg_req_info; 281 282 283 /* vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv */ 284 /* The older SG interface based on the 'sg_header' structure follows. */ 285 /* ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ */ 286 287 #define SG_MAX_SENSE 16 /* this only applies to the sg_header interface */ 288 289 struct sg_header 290 { 291 int pack_len; /* [o] reply_len (ie useless), ignored as input */ 292 int reply_len; /* [i] max length of expected reply (inc. sg_header) */ 293 int pack_id; /* [io] id number of packet (use ints >= 0) */ 294 int result; /* [o] 0==ok, else (+ve) Unix errno (best ignored) */ 295 unsigned int twelve_byte:1; 296 /* [i] Force 12 byte command length for group 6 & 7 commands */ 297 unsigned int target_status:5; /* [o] scsi status from target */ 298 unsigned int host_status:8; /* [o] host status (see "DID" codes) */ 299 unsigned int driver_status:8; /* [o] driver status+suggestion */ 300 unsigned int other_flags:10; /* unused */ 301 unsigned char sense_buffer[SG_MAX_SENSE]; /* [o] Output in 3 cases: 302 when target_status is CHECK_CONDITION or 303 when target_status is COMMAND_TERMINATED or 304 when (driver_status & DRIVER_SENSE) is true. */ 305 }; /* This structure is 36 bytes long on i386 */ 306 307 308 /* IOCTLs: The following are not required (or ignored) when the sg_io_hdr_t 309 interface is used. They are kept for backward compatibility with 310 the original and version 2 drivers. */ 311 312 #define SG_SET_TIMEOUT 0x2201 /* unit: jiffies (10ms on i386) */ 313 #define SG_GET_TIMEOUT 0x2202 /* yield timeout as _return_ value */ 314 315 /* Get/set command queuing state per fd (default is SG_DEF_COMMAND_Q. 316 Each time a sg_io_hdr_t object is seen on this file descriptor, this 317 command queuing flag is set on (overriding the previous setting). */ 318 #define SG_GET_COMMAND_Q 0x2270 /* Yields 0 (queuing off) or 1 (on) */ 319 #define SG_SET_COMMAND_Q 0x2271 /* Change queuing state with 0 or 1 */ 320 321 /* Turn on/off error sense trace (1 and 0 respectively, default is off). 322 Try using: "# cat /proc/scsi/sg/debug" instead in the v3 driver */ 323 #define SG_SET_DEBUG 0x227e /* 0 -> turn off debug */ 324 325 #define SG_NEXT_CMD_LEN 0x2283 /* override SCSI command length with given 326 number on the next write() on this file descriptor */ 327 328 329 /* Defaults, commented if they differ from original sg driver */ 330 #define SG_DEFAULT_TIMEOUT (60*HZ) /* HZ == 'jiffies in 1 second' */ 331 #define SG_DEF_COMMAND_Q 0 /* command queuing is always on when 332 the new interface is used */ 333 #define SG_DEF_UNDERRUN_FLAG 0 334 335 #endif 336