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 17 struct tb_cap_any { 18 union { 19 struct tb_cap_basic basic; 20 struct tb_cap_extended_short extended_short; 21 struct tb_cap_extended_long extended_long; 22 }; 23 } __packed; 24 25 /** 26 * tb_port_find_cap() - Find port capability 27 * @port: Port to find the capability for 28 * @cap: Capability to look 29 * 30 * Returns offset to start of capability or %-ENOENT if no such 31 * capability was found. Negative errno is returned if there was an 32 * error. 33 */ 34 int tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap) 35 { 36 u32 offset; 37 38 /* 39 * DP out adapters claim to implement TMU capability but in 40 * reality they do not so we hard code the adapter specific 41 * capability offset here. 42 */ 43 if (port->config.type == TB_TYPE_DP_HDMI_OUT) 44 offset = 0x39; 45 else 46 offset = 0x1; 47 48 do { 49 struct tb_cap_any header; 50 int ret; 51 52 ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1); 53 if (ret) 54 return ret; 55 56 if (header.basic.cap == cap) 57 return offset; 58 59 offset = header.basic.next; 60 } while (offset); 61 62 return -ENOENT; 63 } 64 65 static int tb_switch_find_cap(struct tb_switch *sw, enum tb_switch_cap cap) 66 { 67 int offset = sw->config.first_cap_offset; 68 69 while (offset > 0 && offset < CAP_OFFSET_MAX) { 70 struct tb_cap_any header; 71 int ret; 72 73 ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1); 74 if (ret) 75 return ret; 76 77 if (header.basic.cap == cap) 78 return offset; 79 80 offset = header.basic.next; 81 } 82 83 return -ENOENT; 84 } 85 86 /** 87 * tb_switch_find_vse_cap() - Find switch vendor specific capability 88 * @sw: Switch to find the capability for 89 * @vsec: Vendor specific capability to look 90 * 91 * Functions enumerates vendor specific capabilities (VSEC) of a switch 92 * and returns offset when capability matching @vsec is found. If no 93 * such capability is found returns %-ENOENT. In case of error returns 94 * negative errno. 95 */ 96 int tb_switch_find_vse_cap(struct tb_switch *sw, enum tb_switch_vse_cap vsec) 97 { 98 struct tb_cap_any header; 99 int offset; 100 101 offset = tb_switch_find_cap(sw, TB_SWITCH_CAP_VSE); 102 if (offset < 0) 103 return offset; 104 105 while (offset > 0 && offset < VSE_CAP_OFFSET_MAX) { 106 int ret; 107 108 ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 2); 109 if (ret) 110 return ret; 111 112 /* 113 * Extended vendor specific capabilities come in two 114 * flavors: short and long. The latter is used when 115 * offset is over 0xff. 116 */ 117 if (offset >= CAP_OFFSET_MAX) { 118 if (header.extended_long.vsec_id == vsec) 119 return offset; 120 offset = header.extended_long.next; 121 } else { 122 if (header.extended_short.vsec_id == vsec) 123 return offset; 124 if (!header.extended_short.length) 125 return -ENOENT; 126 offset = header.extended_short.next; 127 } 128 } 129 130 return -ENOENT; 131 } 132