include/linux/virtio_blk.h

   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_IDENTIFY   8       /* ATA IDENTIFY supported */
  18 #define VIRTIO_BLK_F_FLUSH      9       /* Cache flush command support */
  19
  20 #define VIRTIO_BLK_ID_BYTES     (sizeof(__u16[256]))    /* IDENTIFY DATA */
  21
  22 struct virtio_blk_config {
  23         /* The capacity (in 512-byte sectors). */
  24         __u64 capacity;
  25         /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
  26         __u32 size_max;
  27         /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
  28         __u32 seg_max;
  29         /* geometry the device (if VIRTIO_BLK_F_GEOMETRY) */
  30         struct virtio_blk_geometry {
  31                 __u16 cylinders;
  32                 __u8 heads;
  33                 __u8 sectors;
  34         } geometry;
  35         /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
  36         __u32 blk_size;
  37         __u8 identify[VIRTIO_BLK_ID_BYTES];
  38 } __attribute__((packed));
  39
  40 /*
  41  * Command types
  42  *
  43  * Usage is a bit tricky as some bits are used as flags and some are not.
  44  *
  45  * Rules:
  46  *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
  47  *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
  48  *   and may not be combined with any of the other flags.
  49  */
  50
  51 /* These two define direction. */
  52 #define VIRTIO_BLK_T_IN         0
  53 #define VIRTIO_BLK_T_OUT        1
  54
  55 /* This bit says it's a scsi command, not an actual read or write. */
  56 #define VIRTIO_BLK_T_SCSI_CMD   2
  57
  58 /* Cache flush command */
  59 #define VIRTIO_BLK_T_FLUSH      4
  60
  61 /* Barrier before this op. */
  62 #define VIRTIO_BLK_T_BARRIER    0x80000000
  63
  64 /* This is the first element of the read scatter-gather list. */
  65 struct virtio_blk_outhdr {
  66         /* VIRTIO_BLK_T* */
  67         __u32 type;
  68         /* io priority. */
  69         __u32 ioprio;
  70         /* Sector (ie. 512 byte offset) */
  71         __u64 sector;
  72 };
  73
  74 struct virtio_scsi_inhdr {
  75         __u32 errors;
  76         __u32 data_len;
  77         __u32 sense_len;
  78         __u32 residual;
  79 };
  80
  81 /* And this is the final byte of the write scatter-gather list. */
  82 #define VIRTIO_BLK_S_OK         0
  83 #define VIRTIO_BLK_S_IOERR      1
  84 #define VIRTIO_BLK_S_UNSUPP     2
  85 #endif /* _LINUX_VIRTIO_BLK_H */