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 #define VIRTIO_BLK_F_TOPOLOGY   10      /* Topology information is available */
  19
  20 struct 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. */
  74 struct 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
  83 struct 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 */