text: /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
  #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>
  
  #define TCMU_VERSION "2.0"
  
  /**
   * DOC: Ring Design
   * 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 2
  #define ALIGN_SIZE 64 /* Should be enough for most CPUs */
  #define TCMU_MAILBOX_FLAG_CAP_OOOC (1 << 0) /* Out-of-order completions */
  #define TCMU_MAILBOX_FLAG_CAP_READ_LEN (1 << 1) /* Read data length */
  
  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;
  	__u16 cmd_id;
  	__u8 kflags;
  #define TCMU_UFLAG_UNKNOWN_OP 0x1
  #define TCMU_UFLAG_READ_LEN   0x2
  	__u8 uflags;
  
  } __packed;
  
  #define TCMU_OP_MASK 0x7
  
  static inline enum tcmu_opcode tcmu_hdr_get_op(__u32 len_op)
  {
  	return len_op & TCMU_OP_MASK;
  }
  
  static inline void tcmu_hdr_set_op(__u32 *len_op, enum tcmu_opcode op)
  {
  	*len_op &= ~TCMU_OP_MASK;
  	*len_op |= (op & TCMU_OP_MASK);
  }
  
  static inline __u32 tcmu_hdr_get_len(__u32 len_op)
  {
  	return len_op & ~TCMU_OP_MASK;
  }
  
  static inline void tcmu_hdr_set_len(__u32 *len_op, __u32 len)
  {
  	*len_op &= TCMU_OP_MASK;
  	*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;
  
  	union {
  		struct {
  			__u32 iov_cnt;
  			__u32 iov_bidi_cnt;
  			__u32 iov_dif_cnt;
  			__u64 cdb_off;
  			__u64 __pad1;
  			__u64 __pad2;
  			struct iovec iov[0];
  		} req;
  		struct {
  			__u8 scsi_status;
  			__u8 __pad1;
  			__u16 __pad2;
  			__u32 read_len;
  			char sense_buffer[TCMU_SENSE_BUFFERSIZE];
  		} rsp;
  	};
  
  } __packed;
  
  #define TCMU_OP_ALIGN_SIZE sizeof(__u64)
  
  enum tcmu_genl_cmd {
  	TCMU_CMD_UNSPEC,
  	TCMU_CMD_ADDED_DEVICE,
  	TCMU_CMD_REMOVED_DEVICE,
  	TCMU_CMD_RECONFIG_DEVICE,
  	TCMU_CMD_ADDED_DEVICE_DONE,
  	TCMU_CMD_REMOVED_DEVICE_DONE,
  	TCMU_CMD_RECONFIG_DEVICE_DONE,
  	TCMU_CMD_SET_FEATURES,
  	__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_PAD,
  	TCMU_ATTR_DEV_CFG,
  	TCMU_ATTR_DEV_SIZE,
  	TCMU_ATTR_WRITECACHE,
  	TCMU_ATTR_CMD_STATUS,
  	TCMU_ATTR_DEVICE_ID,
  	TCMU_ATTR_SUPP_KERN_CMD_REPLY,
  	__TCMU_ATTR_MAX,
  };
  #define TCMU_ATTR_MAX (__TCMU_ATTR_MAX - 1)
  
  #endif
  