include/uapi/linux/target_core_user.h

   1 #ifndef __TARGET_CORE_USER_H
   2 #define __TARGET_CORE_USER_H
   3
   4 /* This header will be used by application too */
   5
   6 #include <linux/types.h>
   7 #include <linux/uio.h>
   8
   9 #ifndef __packed
  10 #define __packed                        __attribute__((packed))
  11 #endif
  12
  13 #define TCMU_VERSION "1.0"
  14
  15 /*
  16  * Ring Design
  17  * -----------
  18  *
  19  * The mmaped area is divided into three parts:
  20  * 1) The mailbox (struct tcmu_mailbox, below)
  21  * 2) The command ring
  22  * 3) Everything beyond the command ring (data)
  23  *
  24  * The mailbox tells userspace the offset of the command ring from the
  25  * start of the shared memory region, and how big the command ring is.
  26  *
  27  * The kernel passes SCSI commands to userspace by putting a struct
  28  * tcmu_cmd_entry in the ring, updating mailbox->cmd_head, and poking
  29  * userspace via uio's interrupt mechanism.
  30  *
  31  * tcmu_cmd_entry contains a header. If the header type is PAD,
  32  * userspace should skip hdr->length bytes (mod cmdr_size) to find the
  33  * next cmd_entry.
  34  *
  35  * Otherwise, the entry will contain offsets into the mmaped area that
  36  * contain the cdb and data buffers -- the latter accessible via the
  37  * iov array. iov addresses are also offsets into the shared area.
  38  *
  39  * When userspace is completed handling the command, set
  40  * entry->rsp.scsi_status, fill in rsp.sense_buffer if appropriate,
  41  * and also set mailbox->cmd_tail equal to the old cmd_tail plus
  42  * hdr->length, mod cmdr_size. If cmd_tail doesn't equal cmd_head, it
  43  * should process the next packet the same way, and so on.
  44  */
  45
  46 #define TCMU_MAILBOX_VERSION 1
  47 #define ALIGN_SIZE 64 /* Should be enough for most CPUs */
  48
  49 struct tcmu_mailbox {
  50         __u16 version;
  51         __u16 flags;
  52         __u32 cmdr_off;
  53         __u32 cmdr_size;
  54
  55         __u32 cmd_head;
  56
  57         /* Updated by user. On its own cacheline */
  58         __u32 cmd_tail __attribute__((__aligned__(ALIGN_SIZE)));
  59
  60 } __packed;
  61
  62 enum tcmu_opcode {
  63         TCMU_OP_PAD = 0,
  64         TCMU_OP_CMD,
  65 };
  66
  67 /*
  68  * Only a few opcodes, and length is 8-byte aligned, so use low bits for opcode.
  69  */
  70 struct tcmu_cmd_entry_hdr {
  71                 __u32 len_op;
  72 } __packed;
  73
  74 #define TCMU_OP_MASK 0x7
  75
  76 static inline enum tcmu_opcode tcmu_hdr_get_op(struct tcmu_cmd_entry_hdr *hdr)
  77 {
  78         return hdr->len_op & TCMU_OP_MASK;
  79 }
  80
  81 static inline void tcmu_hdr_set_op(struct tcmu_cmd_entry_hdr *hdr, enum tcmu_opcode op)
  82 {
  83         hdr->len_op &= ~TCMU_OP_MASK;
  84         hdr->len_op |= (op & TCMU_OP_MASK);
  85 }
  86
  87 static inline __u32 tcmu_hdr_get_len(struct tcmu_cmd_entry_hdr *hdr)
  88 {
  89         return hdr->len_op & ~TCMU_OP_MASK;
  90 }
  91
  92 static inline void tcmu_hdr_set_len(struct tcmu_cmd_entry_hdr *hdr, __u32 len)
  93 {
  94         hdr->len_op &= TCMU_OP_MASK;
  95         hdr->len_op |= len;
  96 }
  97
  98 /* Currently the same as SCSI_SENSE_BUFFERSIZE */
  99 #define TCMU_SENSE_BUFFERSIZE 96
 100
 101 struct tcmu_cmd_entry {
 102         struct tcmu_cmd_entry_hdr hdr;
 103
 104         uint16_t cmd_id;
 105         uint16_t __pad1;
 106
 107         union {
 108                 struct {
 109                         uint64_t cdb_off;
 110                         uint64_t iov_cnt;
 111                         struct iovec iov[0];
 112                 } req;
 113                 struct {
 114                         uint8_t scsi_status;
 115                         uint8_t __pad1;
 116                         uint16_t __pad2;
 117                         uint32_t __pad3;
 118                         char sense_buffer[TCMU_SENSE_BUFFERSIZE];
 119                 } rsp;
 120         };
 121
 122 } __packed;
 123
 124 #define TCMU_OP_ALIGN_SIZE sizeof(uint64_t)
 125
 126 enum tcmu_genl_cmd {
 127         TCMU_CMD_UNSPEC,
 128         TCMU_CMD_ADDED_DEVICE,
 129         TCMU_CMD_REMOVED_DEVICE,
 130         __TCMU_CMD_MAX,
 131 };
 132 #define TCMU_CMD_MAX (__TCMU_CMD_MAX - 1)
 133
 134 enum tcmu_genl_attr {
 135         TCMU_ATTR_UNSPEC,
 136         TCMU_ATTR_DEVICE,
 137         TCMU_ATTR_MINOR,
 138         __TCMU_ATTR_MAX,
 139 };
 140 #define TCMU_ATTR_MAX (__TCMU_ATTR_MAX - 1)
 141
 142 #endif