2 files changed, 143 insertions, 0 deletions

diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
index 6cad97485bad..b70237e8bc37 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -374,6 +374,7 @@ header-y += swab.h
 header-y += synclink.h
 header-y += sysctl.h
 header-y += sysinfo.h
+header-y += target_core_user.h
 header-y += taskstats.h
 header-y += tcp.h
 header-y += tcp_metrics.h
diff --git a/include/uapi/linux/target_core_user.h b/include/uapi/linux/target_core_user.h
new file mode 100644
index 000000000000..7dcfbe6771b1
--- /dev/null
+++ b/include/uapi/linux/target_core_user.h
@@ -0,0 +1,142 @@
+#ifndef __TARGET_CORE_USER_H
+#define __TARGET_CORE_USER_H
+
+/* This header will be used by application too */
+
+#include <linux/types.h>
+#include <linux/uio.h>
+
+#ifndef __packed
+#define __packed                        __attribute__((packed))
+#endif
+
+#define TCMU_VERSION "1.0"
+
+/*
+ * Ring Design
+ * -----------
+ *
+ * The mmaped area is divided into three parts:
+ * 1) The mailbox (struct tcmu_mailbox, below)
+ * 2) The command ring
+ * 3) Everything beyond the command ring (data)
+ *
+ * The mailbox tells userspace the offset of the command ring from the
+ * start of the shared memory region, and how big the command ring is.
+ *
+ * The kernel passes SCSI commands to userspace by putting a struct
+ * tcmu_cmd_entry in the ring, updating mailbox->cmd_head, and poking
+ * userspace via uio's interrupt mechanism.
+ *
+ * tcmu_cmd_entry contains a header. If the header type is PAD,
+ * userspace should skip hdr->length bytes (mod cmdr_size) to find the
+ * next cmd_entry.
+ *
+ * Otherwise, the entry will contain offsets into the mmaped area that
+ * contain the cdb and data buffers -- the latter accessible via the
+ * iov array. iov addresses are also offsets into the shared area.
+ *
+ * When userspace is completed handling the command, set
+ * entry->rsp.scsi_status, fill in rsp.sense_buffer if appropriate,
+ * and also set mailbox->cmd_tail equal to the old cmd_tail plus
+ * hdr->length, mod cmdr_size. If cmd_tail doesn't equal cmd_head, it
+ * should process the next packet the same way, and so on.
+ */
+
+#define TCMU_MAILBOX_VERSION 1
+#define ALIGN_SIZE 64 /* Should be enough for most CPUs */
+
+struct tcmu_mailbox {
+        __u16 version;
+        __u16 flags;
+        __u32 cmdr_off;
+        __u32 cmdr_size;
+
+        __u32 cmd_head;
+
+        /* Updated by user. On its own cacheline */
+        __u32 cmd_tail __attribute__((__aligned__(ALIGN_SIZE)));
+
+} __packed;
+
+enum tcmu_opcode {
+        TCMU_OP_PAD = 0,
+        TCMU_OP_CMD,
+};
+
+/*
+ * Only a few opcodes, and length is 8-byte aligned, so use low bits for opcode.
+ */
+struct tcmu_cmd_entry_hdr {
+                __u32 len_op;
+} __packed;
+
+#define TCMU_OP_MASK 0x7
+
+static inline enum tcmu_opcode tcmu_hdr_get_op(struct tcmu_cmd_entry_hdr *hdr)
+{
+        return hdr->len_op & TCMU_OP_MASK;
+}
+
+static inline void tcmu_hdr_set_op(struct tcmu_cmd_entry_hdr *hdr, enum tcmu_opcode op)
+{
+        hdr->len_op &= ~TCMU_OP_MASK;
+        hdr->len_op |= (op & TCMU_OP_MASK);
+}
+
+static inline __u32 tcmu_hdr_get_len(struct tcmu_cmd_entry_hdr *hdr)
+{
+        return hdr->len_op & ~TCMU_OP_MASK;
+}
+
+static inline void tcmu_hdr_set_len(struct tcmu_cmd_entry_hdr *hdr, __u32 len)
+{
+        hdr->len_op &= TCMU_OP_MASK;
+        hdr->len_op |= len;
+}
+
+/* Currently the same as SCSI_SENSE_BUFFERSIZE */
+#define TCMU_SENSE_BUFFERSIZE 96
+
+struct tcmu_cmd_entry {
+        struct tcmu_cmd_entry_hdr hdr;
+
+        uint16_t cmd_id;
+        uint16_t __pad1;
+
+        union {
+                struct {
+                        uint64_t cdb_off;
+                        uint64_t iov_cnt;
+                        struct iovec iov[0];
+                } req;
+                struct {
+                        uint8_t scsi_status;
+                        uint8_t __pad1;
+                        uint16_t __pad2;
+                        uint32_t __pad3;
+                        char sense_buffer[TCMU_SENSE_BUFFERSIZE];
+                } rsp;
+        };
+
+} __packed;
+
+#define TCMU_OP_ALIGN_SIZE sizeof(uint64_t)
+
+enum tcmu_genl_cmd {
+        TCMU_CMD_UNSPEC,
+        TCMU_CMD_ADDED_DEVICE,
+        TCMU_CMD_REMOVED_DEVICE,
+        __TCMU_CMD_MAX,
+};
+#define TCMU_CMD_MAX (__TCMU_CMD_MAX - 1)
+
+enum tcmu_genl_attr {
+        TCMU_ATTR_UNSPEC,
+        TCMU_ATTR_DEVICE,
+        TCMU_ATTR_MINOR,
+        __TCMU_ATTR_MAX,
+};
+#define TCMU_ATTR_MAX (__TCMU_ATTR_MAX - 1)
+
+#endif