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_FLUSH      9       /* Cache flush command support */
  18
  19 struct 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. */
  61 struct 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
  70 struct 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 */