131 lines
2.9 KiB
C
131 lines
2.9 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Thunderbolt Cactus Ridge driver - capabilities lookup
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*
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* Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
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*/
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#include <linux/slab.h>
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#include <linux/errno.h>
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#include "tb.h"
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#define CAP_OFFSET_MAX 0xff
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#define VSE_CAP_OFFSET_MAX 0xffff
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struct tb_cap_any {
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union {
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struct tb_cap_basic basic;
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struct tb_cap_extended_short extended_short;
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struct tb_cap_extended_long extended_long;
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};
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} __packed;
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/**
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* tb_port_find_cap() - Find port capability
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* @port: Port to find the capability for
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* @cap: Capability to look
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*
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* Returns offset to start of capability or %-ENOENT if no such
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* capability was found. Negative errno is returned if there was an
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* error.
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*/
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int tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
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{
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u32 offset;
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/*
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* DP out adapters claim to implement TMU capability but in
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* reality they do not so we hard code the adapter specific
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* capability offset here.
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*/
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if (port->config.type == TB_TYPE_DP_HDMI_OUT)
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offset = 0x39;
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else
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offset = 0x1;
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do {
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struct tb_cap_any header;
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int ret;
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ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);
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if (ret)
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return ret;
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if (header.basic.cap == cap)
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return offset;
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offset = header.basic.next;
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} while (offset);
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return -ENOENT;
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}
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static int tb_switch_find_cap(struct tb_switch *sw, enum tb_switch_cap cap)
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{
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int offset = sw->config.first_cap_offset;
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while (offset > 0 && offset < CAP_OFFSET_MAX) {
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struct tb_cap_any header;
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int ret;
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ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1);
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if (ret)
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return ret;
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if (header.basic.cap == cap)
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return offset;
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offset = header.basic.next;
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}
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return -ENOENT;
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}
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/**
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* tb_switch_find_vse_cap() - Find switch vendor specific capability
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* @sw: Switch to find the capability for
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* @vsec: Vendor specific capability to look
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*
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* Functions enumerates vendor specific capabilities (VSEC) of a switch
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* and returns offset when capability matching @vsec is found. If no
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* such capability is found returns %-ENOENT. In case of error returns
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* negative errno.
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*/
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int tb_switch_find_vse_cap(struct tb_switch *sw, enum tb_switch_vse_cap vsec)
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{
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struct tb_cap_any header;
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int offset;
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offset = tb_switch_find_cap(sw, TB_SWITCH_CAP_VSE);
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if (offset < 0)
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return offset;
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while (offset > 0 && offset < VSE_CAP_OFFSET_MAX) {
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int ret;
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ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 2);
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if (ret)
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return ret;
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/*
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* Extended vendor specific capabilities come in two
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* flavors: short and long. The latter is used when
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* offset is over 0xff.
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*/
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if (offset >= CAP_OFFSET_MAX) {
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if (header.extended_long.vsec_id == vsec)
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return offset;
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offset = header.extended_long.next;
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} else {
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if (header.extended_short.vsec_id == vsec)
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return offset;
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if (!header.extended_short.length)
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return -ENOENT;
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offset = header.extended_short.next;
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}
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}
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return -ENOENT;
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}
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