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 "2.0"
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 2
43 #define ALIGN_SIZE 64 /* Should be enough for most CPUs */
44 
45 /* See https://gcc.gnu.org/onlinedocs/cpp/Stringification.html */
46 #define xstr(s) str(s)
47 #define str(s) #s
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 	__u16 cmd_id;
73 	__u8 kflags;
74 #define TCMU_UFLAG_UNKNOWN_OP 0x1
75 	__u8 uflags;
76 
77 } __packed;
78 
79 #define TCMU_OP_MASK 0x7
80 
81 static inline enum tcmu_opcode tcmu_hdr_get_op(__u32 len_op)
82 {
83 	return len_op & TCMU_OP_MASK;
84 }
85 
86 static inline void tcmu_hdr_set_op(__u32 *len_op, enum tcmu_opcode op)
87 {
88 	*len_op &= ~TCMU_OP_MASK;
89 	*len_op |= (op & TCMU_OP_MASK);
90 }
91 
92 static inline __u32 tcmu_hdr_get_len(__u32 len_op)
93 {
94 	return len_op & ~TCMU_OP_MASK;
95 }
96 
97 static inline void tcmu_hdr_set_len(__u32 *len_op, __u32 len)
98 {
99 	*len_op &= TCMU_OP_MASK;
100 	*len_op |= len;
101 }
102 
103 /* Currently the same as SCSI_SENSE_BUFFERSIZE */
104 #define TCMU_SENSE_BUFFERSIZE 96
105 
106 struct tcmu_cmd_entry {
107 	struct tcmu_cmd_entry_hdr hdr;
108 
109 	union {
110 		struct {
111 			uint32_t iov_cnt;
112 			uint32_t iov_bidi_cnt;
113 			uint32_t iov_dif_cnt;
114 			uint64_t cdb_off;
115 			uint64_t __pad1;
116 			uint64_t __pad2;
117 			struct iovec iov[0];
118 		} req;
119 		struct {
120 			uint8_t scsi_status;
121 			uint8_t __pad1;
122 			uint16_t __pad2;
123 			uint32_t __pad3;
124 			char sense_buffer[TCMU_SENSE_BUFFERSIZE];
125 		} rsp;
126 	};
127 
128 } __packed;
129 
130 #define TCMU_OP_ALIGN_SIZE sizeof(uint64_t)
131 
132 enum tcmu_genl_cmd {
133 	TCMU_CMD_UNSPEC,
134 	TCMU_CMD_ADDED_DEVICE,
135 	TCMU_CMD_REMOVED_DEVICE,
136 	__TCMU_CMD_MAX,
137 };
138 #define TCMU_CMD_MAX (__TCMU_CMD_MAX - 1)
139 
140 enum tcmu_genl_attr {
141 	TCMU_ATTR_UNSPEC,
142 	TCMU_ATTR_DEVICE,
143 	TCMU_ATTR_MINOR,
144 	__TCMU_ATTR_MAX,
145 };
146 #define TCMU_ATTR_MAX (__TCMU_ATTR_MAX - 1)
147 
148 #endif
149