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// SPDX-License-Identifier: GPL-2.0
/*
* Thunderbolt driver - capabilities lookup
*
* Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
* Copyright (C) 2018, Intel Corporation
*/
#include <linux/slab.h>
#include <linux/errno.h>
#include "tb.h"
#define CAP_OFFSET_MAX 0xff
#define VSE_CAP_OFFSET_MAX 0xffff
#define TMU_ACCESS_EN BIT(20)
struct tb_cap_any {
union {
struct tb_cap_basic basic;
struct tb_cap_extended_short extended_short;
struct tb_cap_extended_long extended_long;
};
} __packed;
static int tb_port_enable_tmu(struct tb_port *port, bool enable)
{
struct tb_switch *sw = port->sw;
u32 value, offset;
int ret;
/*
* Legacy devices need to have TMU access enabled before port
* space can be fully accessed.
*/
if (tb_switch_is_lr(sw))
offset = 0x26;
else if (tb_switch_is_er(sw))
offset = 0x2a;
else
return 0;
ret = tb_sw_read(sw, &value, TB_CFG_SWITCH, offset, 1);
if (ret)
return ret;
if (enable)
value |= TMU_ACCESS_EN;
else
value &= ~TMU_ACCESS_EN;
return tb_sw_write(sw, &value, TB_CFG_SWITCH, offset, 1);
}
static void tb_port_dummy_read(struct tb_port *port)
{
/*
* When reading from next capability pointer location in port
* config space the read data is not cleared on LR. To avoid
* reading stale data on next read perform one dummy read after
* port capabilities are walked.
*/
if (tb_switch_is_lr(port->sw)) {
u32 dummy;
tb_port_read(port, &dummy, TB_CFG_PORT, 0, 1);
}
}
static int __tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
{
u32 offset = 1;
do {
struct tb_cap_any header;
int ret;
ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);
if (ret)
return ret;
if (header.basic.cap == cap)
return offset;
offset = header.basic.next;
} while (offset);
return -ENOENT;
}
/**
* tb_port_find_cap() - Find port capability
* @port: Port to find the capability for
* @cap: Capability to look
*
* Returns offset to start of capability or %-ENOENT if no such
* capability was found. Negative errno is returned if there was an
* error.
*/
int tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
{
int ret;
ret = tb_port_enable_tmu(port, true);
if (ret)
return ret;
ret = __tb_port_find_cap(port, cap);
tb_port_dummy_read(port);
tb_port_enable_tmu(port, false);
return ret;
}
static int tb_switch_find_cap(struct tb_switch *sw, enum tb_switch_cap cap)
{
int offset = sw->config.first_cap_offset;
while (offset > 0 && offset < CAP_OFFSET_MAX) {
struct tb_cap_any header;
int ret;
ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1);
if (ret)
return ret;
if (header.basic.cap == cap)
return offset;
offset = header.basic.next;
}
return -ENOENT;
}
/**
* tb_switch_find_vse_cap() - Find switch vendor specific capability
* @sw: Switch to find the capability for
* @vsec: Vendor specific capability to look
*
* Functions enumerates vendor specific capabilities (VSEC) of a switch
* and returns offset when capability matching @vsec is found. If no
* such capability is found returns %-ENOENT. In case of error returns
* negative errno.
*/
int tb_switch_find_vse_cap(struct tb_switch *sw, enum tb_switch_vse_cap vsec)
{
struct tb_cap_any header;
int offset;
offset = tb_switch_find_cap(sw, TB_SWITCH_CAP_VSE);
if (offset < 0)
return offset;
while (offset > 0 && offset < VSE_CAP_OFFSET_MAX) {
int ret;
ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 2);
if (ret)
return ret;
/*
* Extended vendor specific capabilities come in two
* flavors: short and long. The latter is used when
* offset is over 0xff.
*/
if (offset >= CAP_OFFSET_MAX) {
if (header.extended_long.vsec_id == vsec)
return offset;
offset = header.extended_long.next;
} else {
if (header.extended_short.vsec_id == vsec)
return offset;
if (!header.extended_short.length)
return -ENOENT;
offset = header.extended_short.next;
}
}
return -ENOENT;
}
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