183 lines
3.9 KiB
C
183 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Thunderbolt driver - capabilities lookup
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*
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* Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
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* Copyright (C) 2018, Intel Corporation
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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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#define TMU_ACCESS_EN BIT(20)
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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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static int tb_port_enable_tmu(struct tb_port *port, bool enable)
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{
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struct tb_switch *sw = port->sw;
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u32 value, offset;
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int ret;
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/*
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* Legacy devices need to have TMU access enabled before port
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* space can be fully accessed.
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*/
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if (tb_switch_is_lr(sw))
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offset = 0x26;
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else if (tb_switch_is_er(sw))
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offset = 0x2a;
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else
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return 0;
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ret = tb_sw_read(sw, &value, TB_CFG_SWITCH, offset, 1);
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if (ret)
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return ret;
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if (enable)
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value |= TMU_ACCESS_EN;
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else
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value &= ~TMU_ACCESS_EN;
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return tb_sw_write(sw, &value, TB_CFG_SWITCH, offset, 1);
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}
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static void tb_port_dummy_read(struct tb_port *port)
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{
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/*
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* When reading from next capability pointer location in port
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* config space the read data is not cleared on LR. To avoid
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* reading stale data on next read perform one dummy read after
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* port capabilities are walked.
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*/
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if (tb_switch_is_lr(port->sw)) {
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u32 dummy;
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tb_port_read(port, &dummy, TB_CFG_PORT, 0, 1);
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}
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}
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static int __tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
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{
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u32 offset = 1;
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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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/**
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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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int ret;
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ret = tb_port_enable_tmu(port, true);
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if (ret)
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return ret;
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ret = __tb_port_find_cap(port, cap);
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tb_port_dummy_read(port);
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tb_port_enable_tmu(port, false);
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return ret;
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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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