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