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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Thunderbolt driver - capabilities lookup
4 *
5 * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
6 * Copyright (C) 2018, Intel Corporation
7 */
8
9#include <linux/slab.h>
10#include <linux/errno.h>
11
12#include "tb.h"
13
14#define CAP_OFFSET_MAX 0xff
15#define VSE_CAP_OFFSET_MAX 0xffff
16#define TMU_ACCESS_EN BIT(20)
17
18static int tb_port_enable_tmu(struct tb_port *port, bool enable)
19{
20 struct tb_switch *sw = port->sw;
21 u32 value, offset;
22 int ret;
23
24 /*
25 * Legacy devices need to have TMU access enabled before port
26 * space can be fully accessed.
27 */
28 if (tb_switch_is_light_ridge(sw))
29 offset = 0x26;
30 else if (tb_switch_is_eagle_ridge(sw))
31 offset = 0x2a;
32 else
33 return 0;
34
35 ret = tb_sw_read(sw, &value, TB_CFG_SWITCH, offset, 1);
36 if (ret)
37 return ret;
38
39 if (enable)
40 value |= TMU_ACCESS_EN;
41 else
42 value &= ~TMU_ACCESS_EN;
43
44 return tb_sw_write(sw, &value, TB_CFG_SWITCH, offset, 1);
45}
46
47static void tb_port_dummy_read(struct tb_port *port)
48{
49 /*
50 * When reading from next capability pointer location in port
51 * config space the read data is not cleared on LR. To avoid
52 * reading stale data on next read perform one dummy read after
53 * port capabilities are walked.
54 */
55 if (tb_switch_is_light_ridge(port->sw)) {
56 u32 dummy;
57
58 tb_port_read(port, &dummy, TB_CFG_PORT, 0, 1);
59 }
60}
61
62/**
63 * tb_port_next_cap() - Return next capability in the linked list
64 * @port: Port to find the capability for
65 * @offset: Previous capability offset (%0 for start)
66 *
67 * Returns dword offset of the next capability in port config space
68 * capability list and returns it. Passing %0 returns the first entry in
69 * the capability list. If no next capability is found returns %0. In case
70 * of failure returns negative errno.
71 */
72int tb_port_next_cap(struct tb_port *port, unsigned int offset)
73{
74 struct tb_cap_any header;
75 int ret;
76
77 if (!offset)
78 return port->config.first_cap_offset;
79
80 ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);
81 if (ret)
82 return ret;
83
84 return header.basic.next;
85}
86
87static int __tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
88{
89 int offset = 0;
90
91 do {
92 struct tb_cap_any header;
93 int ret;
94
95 offset = tb_port_next_cap(port, offset);
96 if (offset < 0)
97 return offset;
98
99 ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);
100 if (ret)
101 return ret;
102
103 if (header.basic.cap == cap)
104 return offset;
105 } while (offset > 0);
106
107 return -ENOENT;
108}
109
110/**
111 * tb_port_find_cap() - Find port capability
112 * @port: Port to find the capability for
113 * @cap: Capability to look
114 *
115 * Returns offset to start of capability or %-ENOENT if no such
116 * capability was found. Negative errno is returned if there was an
117 * error.
118 */
119int tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
120{
121 int ret;
122
123 ret = tb_port_enable_tmu(port, true);
124 if (ret)
125 return ret;
126
127 ret = __tb_port_find_cap(port, cap);
128
129 tb_port_dummy_read(port);
130 tb_port_enable_tmu(port, false);
131
132 return ret;
133}
134
135/**
136 * tb_switch_next_cap() - Return next capability in the linked list
137 * @sw: Switch to find the capability for
138 * @offset: Previous capability offset (%0 for start)
139 *
140 * Finds dword offset of the next capability in router config space
141 * capability list and returns it. Passing %0 returns the first entry in
142 * the capability list. If no next capability is found returns %0. In case
143 * of failure returns negative errno.
144 */
145int tb_switch_next_cap(struct tb_switch *sw, unsigned int offset)
146{
147 struct tb_cap_any header;
148 int ret;
149
150 if (!offset)
151 return sw->config.first_cap_offset;
152
153 ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 2);
154 if (ret)
155 return ret;
156
157 switch (header.basic.cap) {
158 case TB_SWITCH_CAP_TMU:
159 ret = header.basic.next;
160 break;
161
162 case TB_SWITCH_CAP_VSE:
163 if (!header.extended_short.length)
164 ret = header.extended_long.next;
165 else
166 ret = header.extended_short.next;
167 break;
168
169 default:
170 tb_sw_dbg(sw, "unknown capability %#x at %#x\n",
171 header.basic.cap, offset);
172 ret = -EINVAL;
173 break;
174 }
175
176 return ret >= VSE_CAP_OFFSET_MAX ? 0 : ret;
177}
178
179/**
180 * tb_switch_find_cap() - Find switch capability
181 * @sw: Switch to find the capability for
182 * @cap: Capability to look
183 *
184 * Returns offset to start of capability or %-ENOENT if no such
185 * capability was found. Negative errno is returned if there was an
186 * error.
187 */
188int tb_switch_find_cap(struct tb_switch *sw, enum tb_switch_cap cap)
189{
190 int offset = 0;
191
192 do {
193 struct tb_cap_any header;
194 int ret;
195
196 offset = tb_switch_next_cap(sw, offset);
197 if (offset < 0)
198 return offset;
199
200 ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1);
201 if (ret)
202 return ret;
203
204 if (header.basic.cap == cap)
205 return offset;
206 } while (offset);
207
208 return -ENOENT;
209}
210
211/**
212 * tb_switch_find_vse_cap() - Find switch vendor specific capability
213 * @sw: Switch to find the capability for
214 * @vsec: Vendor specific capability to look
215 *
216 * Functions enumerates vendor specific capabilities (VSEC) of a switch
217 * and returns offset when capability matching @vsec is found. If no
218 * such capability is found returns %-ENOENT. In case of error returns
219 * negative errno.
220 */
221int tb_switch_find_vse_cap(struct tb_switch *sw, enum tb_switch_vse_cap vsec)
222{
223 int offset = 0;
224
225 do {
226 struct tb_cap_any header;
227 int ret;
228
229 offset = tb_switch_next_cap(sw, offset);
230 if (offset < 0)
231 return offset;
232
233 ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1);
234 if (ret)
235 return ret;
236
237 if (header.extended_short.cap == TB_SWITCH_CAP_VSE &&
238 header.extended_short.vsec_id == vsec)
239 return offset;
240 } while (offset);
241
242 return -ENOENT;
243}
1/*
2 * Thunderbolt Cactus Ridge driver - capabilities lookup
3 *
4 * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
5 */
6
7#include <linux/slab.h>
8#include <linux/errno.h>
9
10#include "tb.h"
11
12
13struct tb_cap_any {
14 union {
15 struct tb_cap_basic basic;
16 struct tb_cap_extended_short extended_short;
17 struct tb_cap_extended_long extended_long;
18 };
19} __packed;
20
21static bool tb_cap_is_basic(struct tb_cap_any *cap)
22{
23 /* basic.cap is u8. This checks only the lower 8 bit of cap. */
24 return cap->basic.cap != 5;
25}
26
27static bool tb_cap_is_long(struct tb_cap_any *cap)
28{
29 return !tb_cap_is_basic(cap)
30 && cap->extended_short.next == 0
31 && cap->extended_short.length == 0;
32}
33
34static enum tb_cap tb_cap(struct tb_cap_any *cap)
35{
36 if (tb_cap_is_basic(cap))
37 return cap->basic.cap;
38 else
39 /* extended_short/long have cap at the same offset. */
40 return cap->extended_short.cap;
41}
42
43static u32 tb_cap_next(struct tb_cap_any *cap, u32 offset)
44{
45 int next;
46 if (offset == 1) {
47 /*
48 * The first pointer is part of the switch header and always
49 * a simple pointer.
50 */
51 next = cap->basic.next;
52 } else {
53 /*
54 * Somehow Intel decided to use 3 different types of capability
55 * headers. It is not like anyone could have predicted that
56 * single byte offsets are not enough...
57 */
58 if (tb_cap_is_basic(cap))
59 next = cap->basic.next;
60 else if (!tb_cap_is_long(cap))
61 next = cap->extended_short.next;
62 else
63 next = cap->extended_long.next;
64 }
65 /*
66 * "Hey, we could terminate some capability lists with a null offset
67 * and others with a pointer to the last element." - "Great idea!"
68 */
69 if (next == offset)
70 return 0;
71 return next;
72}
73
74/**
75 * tb_find_cap() - find a capability
76 *
77 * Return: Returns a positive offset if the capability was found and 0 if not.
78 * Returns an error code on failure.
79 */
80int tb_find_cap(struct tb_port *port, enum tb_cfg_space space, enum tb_cap cap)
81{
82 u32 offset = 1;
83 struct tb_cap_any header;
84 int res;
85 int retries = 10;
86 while (retries--) {
87 res = tb_port_read(port, &header, space, offset, 1);
88 if (res) {
89 /* Intel needs some help with linked lists. */
90 if (space == TB_CFG_PORT && offset == 0xa
91 && port->config.type == TB_TYPE_DP_HDMI_OUT) {
92 offset = 0x39;
93 continue;
94 }
95 return res;
96 }
97 if (offset != 1) {
98 if (tb_cap(&header) == cap)
99 return offset;
100 if (tb_cap_is_long(&header)) {
101 /* tb_cap_extended_long is 2 dwords */
102 res = tb_port_read(port, &header, space,
103 offset, 2);
104 if (res)
105 return res;
106 }
107 }
108 offset = tb_cap_next(&header, offset);
109 if (!offset)
110 return 0;
111 }
112 tb_port_WARN(port,
113 "run out of retries while looking for cap %#x in config space %d, last offset: %#x\n",
114 cap, space, offset);
115 return -EIO;
116}