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
19struct virtio_blk_config {
20	/* The capacity (in 512-byte sectors). */
21	__u64 capacity;
22	/* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
23	__u32 size_max;
24	/* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
25	__u32 seg_max;
26	/* geometry the device (if VIRTIO_BLK_F_GEOMETRY) */
27	struct virtio_blk_geometry {
28		__u16 cylinders;
29		__u8 heads;
30		__u8 sectors;
31	} geometry;
32	/* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
33	__u32 blk_size;
34} __attribute__((packed));
35
36/*
37 * Command types
38 *
39 * Usage is a bit tricky as some bits are used as flags and some are not.
40 *
41 * Rules:
42 *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
43 *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
44 *   and may not be combined with any of the other flags.
45 */
46
47/* These two define direction. */
48#define VIRTIO_BLK_T_IN		0
49#define VIRTIO_BLK_T_OUT	1
50
51/* This bit says it's a scsi command, not an actual read or write. */
52#define VIRTIO_BLK_T_SCSI_CMD	2
53
54/* Cache flush command */
55#define VIRTIO_BLK_T_FLUSH	4
56
57/* Barrier before this op. */
58#define VIRTIO_BLK_T_BARRIER	0x80000000
59
60/* This is the first element of the read scatter-gather list. */
61struct virtio_blk_outhdr {
62	/* VIRTIO_BLK_T* */
63	__u32 type;
64	/* io priority. */
65	__u32 ioprio;
66	/* Sector (ie. 512 byte offset) */
67	__u64 sector;
68};
69
70struct virtio_scsi_inhdr {
71	__u32 errors;
72	__u32 data_len;
73	__u32 sense_len;
74	__u32 residual;
75};
76
77/* And this is the final byte of the write scatter-gather list. */
78#define VIRTIO_BLK_S_OK		0
79#define VIRTIO_BLK_S_IOERR	1
80#define VIRTIO_BLK_S_UNSUPP	2
81#endif /* _LINUX_VIRTIO_BLK_H */
82