1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Thunderbolt Cactus Ridge driver - capabilities lookup
4 *
5 * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
6 */
7
8 #include <linux/slab.h>
9 #include <linux/errno.h>
10
11 #include "tb.h"
12
13 #define CAP_OFFSET_MAX 0xff
14 #define VSE_CAP_OFFSET_MAX 0xffff
15
16 struct tb_cap_any {
17 union {
18 struct tb_cap_basic basic;
19 struct tb_cap_extended_short extended_short;
20 struct tb_cap_extended_long extended_long;
21 };
22 } __packed;
23
24 /**
25 * tb_port_find_cap() - Find port capability
26 * @port: Port to find the capability for
27 * @cap: Capability to look
28 *
29 * Returns offset to start of capability or %-ENOENT if no such
30 * capability was found. Negative errno is returned if there was an
31 * error.
32 */
tb_port_find_cap(struct tb_port * port,enum tb_port_cap cap)33 int tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
34 {
35 u32 offset;
36
37 /*
38 * DP out adapters claim to implement TMU capability but in
39 * reality they do not so we hard code the adapter specific
40 * capability offset here.
41 */
42 if (port->config.type == TB_TYPE_DP_HDMI_OUT)
43 offset = 0x39;
44 else
45 offset = 0x1;
46
47 do {
48 struct tb_cap_any header;
49 int ret;
50
51 ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);
52 if (ret)
53 return ret;
54
55 if (header.basic.cap == cap)
56 return offset;
57
58 offset = header.basic.next;
59 } while (offset);
60
61 return -ENOENT;
62 }
63
tb_switch_find_cap(struct tb_switch * sw,enum tb_switch_cap cap)64 static int tb_switch_find_cap(struct tb_switch *sw, enum tb_switch_cap cap)
65 {
66 int offset = sw->config.first_cap_offset;
67
68 while (offset > 0 && offset < CAP_OFFSET_MAX) {
69 struct tb_cap_any header;
70 int ret;
71
72 ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1);
73 if (ret)
74 return ret;
75
76 if (header.basic.cap == cap)
77 return offset;
78
79 offset = header.basic.next;
80 }
81
82 return -ENOENT;
83 }
84
85 /**
86 * tb_switch_find_vse_cap() - Find switch vendor specific capability
87 * @sw: Switch to find the capability for
88 * @vsec: Vendor specific capability to look
89 *
90 * Functions enumerates vendor specific capabilities (VSEC) of a switch
91 * and returns offset when capability matching @vsec is found. If no
92 * such capability is found returns %-ENOENT. In case of error returns
93 * negative errno.
94 */
tb_switch_find_vse_cap(struct tb_switch * sw,enum tb_switch_vse_cap vsec)95 int tb_switch_find_vse_cap(struct tb_switch *sw, enum tb_switch_vse_cap vsec)
96 {
97 struct tb_cap_any header;
98 int offset;
99
100 offset = tb_switch_find_cap(sw, TB_SWITCH_CAP_VSE);
101 if (offset < 0)
102 return offset;
103
104 while (offset > 0 && offset < VSE_CAP_OFFSET_MAX) {
105 int ret;
106
107 ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 2);
108 if (ret)
109 return ret;
110
111 /*
112 * Extended vendor specific capabilities come in two
113 * flavors: short and long. The latter is used when
114 * offset is over 0xff.
115 */
116 if (offset >= CAP_OFFSET_MAX) {
117 if (header.extended_long.vsec_id == vsec)
118 return offset;
119 offset = header.extended_long.next;
120 } else {
121 if (header.extended_short.vsec_id == vsec)
122 return offset;
123 if (!header.extended_short.length)
124 return -ENOENT;
125 offset = header.extended_short.next;
126 }
127 }
128
129 return -ENOENT;
130 }
131
