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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#include <linux/types.h>
6#include <linux/virtio_ids.h>
7#include <linux/virtio_config.h>
8
9/* Feature bits */
10#define VIRTIO_BLK_F_BARRIER 0 /* Does host support barriers? */
11#define VIRTIO_BLK_F_SIZE_MAX 1 /* Indicates maximum segment size */
12#define VIRTIO_BLK_F_SEG_MAX 2 /* Indicates maximum # of segments */
13#define VIRTIO_BLK_F_GEOMETRY 4 /* Legacy geometry available */
14#define VIRTIO_BLK_F_RO 5 /* Disk is read-only */
15#define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/
16#define VIRTIO_BLK_F_SCSI 7 /* Supports scsi command passthru */
17#define VIRTIO_BLK_F_FLUSH 9 /* Cache flush command support */
18#define VIRTIO_BLK_F_TOPOLOGY 10 /* Topology information is available */
19
20struct virtio_blk_config {
21 /* The capacity (in 512-byte sectors). */
22 __u64 capacity;
23 /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
24 __u32 size_max;
25 /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
26 __u32 seg_max;
27 /* geometry the device (if VIRTIO_BLK_F_GEOMETRY) */
28 struct virtio_blk_geometry {
29 __u16 cylinders;
30 __u8 heads;
31 __u8 sectors;
32 } geometry;
33
34 /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
35 __u32 blk_size;
36
37 /* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY */
38 /* exponent for physical block per logical block. */
39 __u8 physical_block_exp;
40 /* alignment offset in logical blocks. */
41 __u8 alignment_offset;
42 /* minimum I/O size without performance penalty in logical blocks. */
43 __u16 min_io_size;
44 /* optimal sustained I/O size in logical blocks. */
45 __u32 opt_io_size;
46
47} __attribute__((packed));
48
49/*
50 * Command types
51 *
52 * Usage is a bit tricky as some bits are used as flags and some are not.
53 *
54 * Rules:
55 * VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
56 * VIRTIO_BLK_T_BARRIER. VIRTIO_BLK_T_FLUSH is a command of its own
57 * and may not be combined with any of the other flags.
58 */
59
60/* These two define direction. */
61#define VIRTIO_BLK_T_IN 0
62#define VIRTIO_BLK_T_OUT 1
63
64/* This bit says it's a scsi command, not an actual read or write. */
65#define VIRTIO_BLK_T_SCSI_CMD 2
66
67/* Cache flush command */
68#define VIRTIO_BLK_T_FLUSH 4
69
70/* Barrier before this op. */
71#define VIRTIO_BLK_T_BARRIER 0x80000000
72
73/* This is the first element of the read scatter-gather list. */
74struct virtio_blk_outhdr {
75 /* VIRTIO_BLK_T* */
76 __u32 type;
77 /* io priority. */
78 __u32 ioprio;
79 /* Sector (ie. 512 byte offset) */
80 __u64 sector;
81};
82
83struct virtio_scsi_inhdr {
84 __u32 errors;
85 __u32 data_len;
86 __u32 sense_len;
87 __u32 residual;
88};
89
90/* And this is the final byte of the write scatter-gather list. */
91#define VIRTIO_BLK_S_OK 0
92#define VIRTIO_BLK_S_IOERR 1
93#define VIRTIO_BLK_S_UNSUPP 2
94#endif /* _LINUX_VIRTIO_BLK_H */