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Linux/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 #ifdef __KERNEL__
 74 extern int sg_big_buff; /* for sysctl */
 75 #endif
 76 
 77 /* New interface introduced in the 3.x SG drivers follows */
 78 
 79 typedef struct sg_iovec /* same structure as used by readv() Linux system */
 80 {                       /* call. It defines one scatter-gather element. */
 81     void __user *iov_base;      /* Starting address  */
 82     size_t iov_len;             /* Length in bytes  */
 83 } sg_iovec_t;
 84 
 85 
 86 typedef struct sg_io_hdr
 87 {
 88     int interface_id;           /* [i] 'S' for SCSI generic (required) */
 89     int dxfer_direction;        /* [i] data transfer direction  */
 90     unsigned char cmd_len;      /* [i] SCSI command length ( <= 16 bytes) */
 91     unsigned char mx_sb_len;    /* [i] max length to write to sbp */
 92     unsigned short iovec_count; /* [i] 0 implies no scatter gather */
 93     unsigned int dxfer_len;     /* [i] byte count of data transfer */
 94     void __user *dxferp;        /* [i], [*io] points to data transfer memory
 95                                               or scatter gather list */
 96     unsigned char __user *cmdp; /* [i], [*i] points to command to perform */
 97     void __user *sbp;           /* [i], [*o] points to sense_buffer memory */
 98     unsigned int timeout;       /* [i] MAX_UINT->no timeout (unit: millisec) */
 99     unsigned int flags;         /* [i] 0 -> default, see SG_FLAG... */
100     int pack_id;                /* [i->o] unused internally (normally) */
101     void __user * usr_ptr;      /* [i->o] unused internally */
102     unsigned char status;       /* [o] scsi status */
103     unsigned char masked_status;/* [o] shifted, masked scsi status */
104     unsigned char msg_status;   /* [o] messaging level data (optional) */
105     unsigned char sb_len_wr;    /* [o] byte count actually written to sbp */
106     unsigned short host_status; /* [o] errors from host adapter */
107     unsigned short driver_status;/* [o] errors from software driver */
108     int resid;                  /* [o] dxfer_len - actual_transferred */
109     unsigned int duration;      /* [o] time taken by cmd (unit: millisec) */
110     unsigned int info;          /* [o] auxiliary information */
111 } sg_io_hdr_t;  /* 64 bytes long (on i386) */
112 
113 #define SG_INTERFACE_ID_ORIG 'S'
114 
115 /* Use negative values to flag difference from original sg_header structure */
116 #define SG_DXFER_NONE (-1)      /* e.g. a SCSI Test Unit Ready command */
117 #define SG_DXFER_TO_DEV (-2)    /* e.g. a SCSI WRITE command */
118 #define SG_DXFER_FROM_DEV (-3)  /* e.g. a SCSI READ command */
119 #define SG_DXFER_TO_FROM_DEV (-4) /* treated like SG_DXFER_FROM_DEV with the
120                                    additional property than during indirect
121                                    IO the user buffer is copied into the
122                                    kernel buffers before the transfer */
123 #define SG_DXFER_UNKNOWN (-5)   /* Unknown data direction */
124 
125 /* following flag values can be "or"-ed together */
126 #define SG_FLAG_DIRECT_IO 1     /* default is indirect IO */
127 #define SG_FLAG_UNUSED_LUN_INHIBIT 2   /* default is overwrite lun in SCSI */
128                                 /* command block (when <= SCSI_2) */
129 #define SG_FLAG_MMAP_IO 4       /* request memory mapped IO */
130 #define SG_FLAG_NO_DXFER 0x10000 /* no transfer of kernel buffers to/from */
131                                 /* user space (debug indirect IO) */
132 
133 /* following 'info' values are "or"-ed together */
134 #define SG_INFO_OK_MASK 0x1
135 #define SG_INFO_OK 0x0          /* no sense, host nor driver "noise" */
136 #define SG_INFO_CHECK 0x1       /* something abnormal happened */
137 
138 #define SG_INFO_DIRECT_IO_MASK 0x6
139 #define SG_INFO_INDIRECT_IO 0x0 /* data xfer via kernel buffers (or no xfer) */
140 #define SG_INFO_DIRECT_IO 0x2   /* direct IO requested and performed */
141 #define SG_INFO_MIXED_IO 0x4    /* part direct, part indirect IO */
142 
143 
144 typedef struct sg_scsi_id { /* used by SG_GET_SCSI_ID ioctl() */
145     int host_no;        /* as in "scsi<n>" where 'n' is one of 0, 1, 2 etc */
146     int channel;
147     int scsi_id;        /* scsi id of target device */
148     int lun;
149     int scsi_type;      /* TYPE_... defined in scsi/scsi.h */
150     short h_cmd_per_lun;/* host (adapter) maximum commands per lun */
151     short d_queue_depth;/* device (or adapter) maximum queue length */
152     int unused[2];      /* probably find a good use, set 0 for now */
153 } sg_scsi_id_t; /* 32 bytes long on i386 */
154 
155 typedef struct sg_req_info { /* used by SG_GET_REQUEST_TABLE ioctl() */
156     char req_state;     /* 0 -> not used, 1 -> written, 2 -> ready to read */
157     char orphan;        /* 0 -> normal request, 1 -> from interruped SG_IO */
158     char sg_io_owned;   /* 0 -> complete with read(), 1 -> owned by SG_IO */
159     char problem;       /* 0 -> no problem detected, 1 -> error to report */
160     int pack_id;        /* pack_id associated with request */
161     void __user *usr_ptr;     /* user provided pointer (in new interface) */
162     unsigned int duration; /* millisecs elapsed since written (req_state==1)
163                               or request duration (req_state==2) */
164     int unused;
165 } sg_req_info_t; /* 20 bytes long on i386 */
166 
167 
168 /* IOCTLs: Those ioctls that are relevant to the SG 3.x drivers follow.
169  [Those that only apply to the SG 2.x drivers are at the end of the file.]
170  (_GET_s yield result via 'int *' 3rd argument unless otherwise indicated) */
171 
172 #define SG_EMULATED_HOST 0x2203 /* true for emulated host adapter (ATAPI) */
173 
174 /* Used to configure SCSI command transformation layer for ATAPI devices */
175 /* Only supported by the ide-scsi driver */
176 #define SG_SET_TRANSFORM 0x2204 /* N.B. 3rd arg is not pointer but value: */
177                       /* 3rd arg = 0 to disable transform, 1 to enable it */
178 #define SG_GET_TRANSFORM 0x2205
179 
180 #define SG_SET_RESERVED_SIZE 0x2275  /* request a new reserved buffer size */
181 #define SG_GET_RESERVED_SIZE 0x2272  /* actual size of reserved buffer */
182 
183 /* The following ioctl has a 'sg_scsi_id_t *' object as its 3rd argument. */
184 #define SG_GET_SCSI_ID 0x2276   /* Yields fd's bus, chan, dev, lun + type */
185 /* SCSI id information can also be obtained from SCSI_IOCTL_GET_IDLUN */
186 
187 /* Override host setting and always DMA using low memory ( <16MB on i386) */
188 #define SG_SET_FORCE_LOW_DMA 0x2279  /* 0-> use adapter setting, 1-> force */
189 #define SG_GET_LOW_DMA 0x227a   /* 0-> use all ram for dma; 1-> low dma ram */
190 
191 /* When SG_SET_FORCE_PACK_ID set to 1, pack_id is input to read() which
192    tries to fetch a packet with a matching pack_id, waits, or returns EAGAIN.
193    If pack_id is -1 then read oldest waiting. When ...FORCE_PACK_ID set to 0
194    then pack_id ignored by read() and oldest readable fetched. */
195 #define SG_SET_FORCE_PACK_ID 0x227b
196 #define SG_GET_PACK_ID 0x227c /* Yields oldest readable pack_id (or -1) */
197 
198 #define SG_GET_NUM_WAITING 0x227d /* Number of commands awaiting read() */
199 
200 /* Yields max scatter gather tablesize allowed by current host adapter */
201 #define SG_GET_SG_TABLESIZE 0x227F  /* 0 implies can't do scatter gather */
202 
203 #define SG_GET_VERSION_NUM 0x2282 /* Example: version 2.1.34 yields 20134 */
204 
205 /* Returns -EBUSY if occupied. 3rd argument pointer to int (see next) */
206 #define SG_SCSI_RESET 0x2284
207 /* Associated values that can be given to SG_SCSI_RESET follow */
208 #define         SG_SCSI_RESET_NOTHING   0
209 #define         SG_SCSI_RESET_DEVICE    1
210 #define         SG_SCSI_RESET_BUS       2
211 #define         SG_SCSI_RESET_HOST      3
212 #define         SG_SCSI_RESET_TARGET    4
213 
214 /* synchronous SCSI command ioctl, (only in version 3 interface) */
215 #define SG_IO 0x2285   /* similar effect as write() followed by read() */
216 
217 #define SG_GET_REQUEST_TABLE 0x2286   /* yields table of active requests */
218 
219 /* How to treat EINTR during SG_IO ioctl(), only in SG 3.x series */
220 #define SG_SET_KEEP_ORPHAN 0x2287 /* 1 -> hold for read(), 0 -> drop (def) */
221 #define SG_GET_KEEP_ORPHAN 0x2288
222 
223 /* yields scsi midlevel's access_count for this SCSI device */
224 #define SG_GET_ACCESS_COUNT 0x2289  
225 
226 
227 #define SG_SCATTER_SZ (8 * 4096)
228 /* Largest size (in bytes) a single scatter-gather list element can have.
229    The value used by the driver is 'max(SG_SCATTER_SZ, PAGE_SIZE)'.
230    This value should be a power of 2 (and may be rounded up internally).
231    If scatter-gather is not supported by adapter then this value is the
232    largest data block that can be read/written by a single scsi command. */
233 
234 #define SG_DEFAULT_RETRIES 0
235 
236 /* Defaults, commented if they differ from original sg driver */
237 #define SG_DEF_FORCE_LOW_DMA 0  /* was 1 -> memory below 16MB on i386 */
238 #define SG_DEF_FORCE_PACK_ID 0
239 #define SG_DEF_KEEP_ORPHAN 0
240 #define SG_DEF_RESERVED_SIZE SG_SCATTER_SZ /* load time option */
241 
242 /* maximum outstanding requests, write() yields EDOM if exceeded */
243 #define SG_MAX_QUEUE 16
244 
245 #define SG_BIG_BUFF SG_DEF_RESERVED_SIZE    /* for backward compatibility */
246 
247 /* Alternate style type names, "..._t" variants preferred */
248 typedef struct sg_io_hdr Sg_io_hdr;
249 typedef struct sg_io_vec Sg_io_vec;
250 typedef struct sg_scsi_id Sg_scsi_id;
251 typedef struct sg_req_info Sg_req_info;
252 
253 
254 /* vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv */
255 /*   The older SG interface based on the 'sg_header' structure follows.   */
256 /* ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ */
257 
258 #define SG_MAX_SENSE 16   /* this only applies to the sg_header interface */
259 
260 struct sg_header
261 {
262     int pack_len;    /* [o] reply_len (ie useless), ignored as input */
263     int reply_len;   /* [i] max length of expected reply (inc. sg_header) */
264     int pack_id;     /* [io] id number of packet (use ints >= 0) */
265     int result;      /* [o] 0==ok, else (+ve) Unix errno (best ignored) */
266     unsigned int twelve_byte:1;
267         /* [i] Force 12 byte command length for group 6 & 7 commands  */
268     unsigned int target_status:5;   /* [o] scsi status from target */
269     unsigned int host_status:8;     /* [o] host status (see "DID" codes) */
270     unsigned int driver_status:8;   /* [o] driver status+suggestion */
271     unsigned int other_flags:10;    /* unused */
272     unsigned char sense_buffer[SG_MAX_SENSE]; /* [o] Output in 3 cases:
273            when target_status is CHECK_CONDITION or
274            when target_status is COMMAND_TERMINATED or
275            when (driver_status & DRIVER_SENSE) is true. */
276 };      /* This structure is 36 bytes long on i386 */
277 
278 
279 /* IOCTLs: The following are not required (or ignored) when the sg_io_hdr_t
280            interface is used. They are kept for backward compatibility with
281            the original and version 2 drivers. */
282 
283 #define SG_SET_TIMEOUT 0x2201  /* unit: jiffies (10ms on i386) */
284 #define SG_GET_TIMEOUT 0x2202  /* yield timeout as _return_ value */
285 
286 /* Get/set command queuing state per fd (default is SG_DEF_COMMAND_Q.
287    Each time a sg_io_hdr_t object is seen on this file descriptor, this
288    command queuing flag is set on (overriding the previous setting). */
289 #define SG_GET_COMMAND_Q 0x2270   /* Yields 0 (queuing off) or 1 (on) */
290 #define SG_SET_COMMAND_Q 0x2271   /* Change queuing state with 0 or 1 */
291 
292 /* Turn on/off error sense trace (1 and 0 respectively, default is off).
293    Try using: "# cat /proc/scsi/sg/debug" instead in the v3 driver */
294 #define SG_SET_DEBUG 0x227e    /* 0 -> turn off debug */
295 
296 #define SG_NEXT_CMD_LEN 0x2283  /* override SCSI command length with given
297                    number on the next write() on this file descriptor */
298 
299 
300 /* Defaults, commented if they differ from original sg driver */
301 #ifdef __KERNEL__
302 #define SG_DEFAULT_TIMEOUT_USER (60*USER_HZ) /* HZ == 'jiffies in 1 second' */
303 #else
304 #define SG_DEFAULT_TIMEOUT      (60*HZ)      /* HZ == 'jiffies in 1 second' */
305 #endif
306 
307 #define SG_DEF_COMMAND_Q 0     /* command queuing is always on when
308                                   the new interface is used */
309 #define SG_DEF_UNDERRUN_FLAG 0
310 
311 #endif
312 

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