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virtio_blk.h
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1 #ifndef _LINUX_VIRTIO_BLK_H
2 #define _LINUX_VIRTIO_BLK_H
3 /* This header is BSD licensed so anyone can use the definitions to implement
4  * compatible drivers/servers.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  * notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  * notice, this list of conditions and the following disclaimer in the
13  * documentation and/or other materials provided with the distribution.
14  * 3. Neither the name of IBM nor the names of its contributors
15  * may be used to endorse or promote products derived from this software
16  * without specific prior written permission.
17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE. */
28 #include <linux/types.h>
29 #include <linux/virtio_ids.h>
30 #include <linux/virtio_config.h>
31 
32 /* Feature bits */
33 #define VIRTIO_BLK_F_BARRIER 0 /* Does host support barriers? */
34 #define VIRTIO_BLK_F_SIZE_MAX 1 /* Indicates maximum segment size */
35 #define VIRTIO_BLK_F_SEG_MAX 2 /* Indicates maximum # of segments */
36 #define VIRTIO_BLK_F_GEOMETRY 4 /* Legacy geometry available */
37 #define VIRTIO_BLK_F_RO 5 /* Disk is read-only */
38 #define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/
39 #define VIRTIO_BLK_F_SCSI 7 /* Supports scsi command passthru */
40 #define VIRTIO_BLK_F_WCE 9 /* Writeback mode enabled after reset */
41 #define VIRTIO_BLK_F_TOPOLOGY 10 /* Topology information is available */
42 #define VIRTIO_BLK_F_CONFIG_WCE 11 /* Writeback mode available in config */
43 
44 #ifndef __KERNEL__
45 /* Old (deprecated) name for VIRTIO_BLK_F_WCE. */
46 #define VIRTIO_BLK_F_FLUSH VIRTIO_BLK_F_WCE
47 #endif
48 
49 #define VIRTIO_BLK_ID_BYTES 20 /* ID string length */
50 
52  /* The capacity (in 512-byte sectors). */
54  /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
56  /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
58  /* geometry the device (if VIRTIO_BLK_F_GEOMETRY) */
63  } geometry;
64 
65  /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
67 
68  /* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY */
69  /* exponent for physical block per logical block. */
71  /* alignment offset in logical blocks. */
73  /* minimum I/O size without performance penalty in logical blocks. */
75  /* optimal sustained I/O size in logical blocks. */
77 
78  /* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
80 } __attribute__((packed));
81 
82 /*
83  * Command types
84  *
85  * Usage is a bit tricky as some bits are used as flags and some are not.
86  *
87  * Rules:
88  * VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
89  * VIRTIO_BLK_T_BARRIER. VIRTIO_BLK_T_FLUSH is a command of its own
90  * and may not be combined with any of the other flags.
91  */
92 
93 /* These two define direction. */
94 #define VIRTIO_BLK_T_IN 0
95 #define VIRTIO_BLK_T_OUT 1
96 
97 /* This bit says it's a scsi command, not an actual read or write. */
98 #define VIRTIO_BLK_T_SCSI_CMD 2
99 
100 /* Cache flush command */
101 #define VIRTIO_BLK_T_FLUSH 4
102 
103 /* Get device ID command */
104 #define VIRTIO_BLK_T_GET_ID 8
106 /* Barrier before this op. */
107 #define VIRTIO_BLK_T_BARRIER 0x80000000
109 /* This is the first element of the read scatter-gather list. */
111  /* VIRTIO_BLK_T* */
113  /* io priority. */
115  /* Sector (ie. 512 byte offset) */
117 };
118 
124 };
125 
126 /* And this is the final byte of the write scatter-gather list. */
127 #define VIRTIO_BLK_S_OK 0
128 #define VIRTIO_BLK_S_IOERR 1
129 #define VIRTIO_BLK_S_UNSUPP 2
130 #endif /* _LINUX_VIRTIO_BLK_H */