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