1 // SPDX-License-Identifier: GPL-2.0
3 * Thunderbolt Cactus Ridge driver - capabilities lookup
5 * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
8 #include <linux/slab.h>
9 #include <linux/errno.h>
13 #define CAP_OFFSET_MAX 0xff
14 #define VSE_CAP_OFFSET_MAX 0xffff
18 struct tb_cap_basic basic;
19 struct tb_cap_extended_short extended_short;
20 struct tb_cap_extended_long extended_long;
25 * tb_port_find_cap() - Find port capability
26 * @port: Port to find the capability for
27 * @cap: Capability to look
29 * Returns offset to start of capability or %-ENOENT if no such
30 * capability was found. Negative errno is returned if there was an
33 int tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
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.
42 if (port->config.type == TB_TYPE_DP_HDMI_OUT)
48 struct tb_cap_any header;
51 ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);
55 if (header.basic.cap == cap)
58 offset = header.basic.next;
64 static int tb_switch_find_cap(struct tb_switch *sw, enum tb_switch_cap cap)
66 int offset = sw->config.first_cap_offset;
68 while (offset > 0 && offset < CAP_OFFSET_MAX) {
69 struct tb_cap_any header;
72 ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1);
76 if (header.basic.cap == cap)
79 offset = header.basic.next;
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
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
95 int tb_switch_find_vse_cap(struct tb_switch *sw, enum tb_switch_vse_cap vsec)
97 struct tb_cap_any header;
100 offset = tb_switch_find_cap(sw, TB_SWITCH_CAP_VSE);
104 while (offset > 0 && offset < VSE_CAP_OFFSET_MAX) {
107 ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 2);
112 * Extended vendor specific capabilities come in two
113 * flavors: short and long. The latter is used when
114 * offset is over 0xff.
116 if (offset >= CAP_OFFSET_MAX) {
117 if (header.extended_long.vsec_id == vsec)
119 offset = header.extended_long.next;
121 if (header.extended_short.vsec_id == vsec)
123 if (!header.extended_short.length)
125 offset = header.extended_short.next;