mirror of
https://github.com/torvalds/linux.git
synced 2024-11-15 16:41:58 +00:00
e2b8785ed3
Thunderbolt config areas contain capability lists similar to those found on pci devices. This patch introduces a tb_find_cap utility method to search for capabilities. Signed-off-by: Andreas Noever <andreas.noever@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
117 lines
2.7 KiB
C
117 lines
2.7 KiB
C
/*
|
|
* Thunderbolt Cactus Ridge driver - capabilities lookup
|
|
*
|
|
* Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
|
|
*/
|
|
|
|
#include <linux/slab.h>
|
|
#include <linux/errno.h>
|
|
|
|
#include "tb.h"
|
|
|
|
|
|
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 bool tb_cap_is_basic(struct tb_cap_any *cap)
|
|
{
|
|
/* basic.cap is u8. This checks only the lower 8 bit of cap. */
|
|
return cap->basic.cap != 5;
|
|
}
|
|
|
|
static bool tb_cap_is_long(struct tb_cap_any *cap)
|
|
{
|
|
return !tb_cap_is_basic(cap)
|
|
&& cap->extended_short.next == 0
|
|
&& cap->extended_short.length == 0;
|
|
}
|
|
|
|
static enum tb_cap tb_cap(struct tb_cap_any *cap)
|
|
{
|
|
if (tb_cap_is_basic(cap))
|
|
return cap->basic.cap;
|
|
else
|
|
/* extended_short/long have cap at the same offset. */
|
|
return cap->extended_short.cap;
|
|
}
|
|
|
|
static u32 tb_cap_next(struct tb_cap_any *cap, u32 offset)
|
|
{
|
|
int next;
|
|
if (offset == 1) {
|
|
/*
|
|
* The first pointer is part of the switch header and always
|
|
* a simple pointer.
|
|
*/
|
|
next = cap->basic.next;
|
|
} else {
|
|
/*
|
|
* Somehow Intel decided to use 3 different types of capability
|
|
* headers. It is not like anyone could have predicted that
|
|
* single byte offsets are not enough...
|
|
*/
|
|
if (tb_cap_is_basic(cap))
|
|
next = cap->basic.next;
|
|
else if (!tb_cap_is_long(cap))
|
|
next = cap->extended_short.next;
|
|
else
|
|
next = cap->extended_long.next;
|
|
}
|
|
/*
|
|
* "Hey, we could terminate some capability lists with a null offset
|
|
* and others with a pointer to the last element." - "Great idea!"
|
|
*/
|
|
if (next == offset)
|
|
return 0;
|
|
return next;
|
|
}
|
|
|
|
/**
|
|
* tb_find_cap() - find a capability
|
|
*
|
|
* Return: Returns a positive offset if the capability was found and 0 if not.
|
|
* Returns an error code on failure.
|
|
*/
|
|
int tb_find_cap(struct tb_port *port, enum tb_cfg_space space, enum tb_cap cap)
|
|
{
|
|
u32 offset = 1;
|
|
struct tb_cap_any header;
|
|
int res;
|
|
int retries = 10;
|
|
while (retries--) {
|
|
res = tb_port_read(port, &header, space, offset, 1);
|
|
if (res) {
|
|
/* Intel needs some help with linked lists. */
|
|
if (space == TB_CFG_PORT && offset == 0xa
|
|
&& port->config.type == TB_TYPE_DP_HDMI_OUT) {
|
|
offset = 0x39;
|
|
continue;
|
|
}
|
|
return res;
|
|
}
|
|
if (offset != 1) {
|
|
if (tb_cap(&header) == cap)
|
|
return offset;
|
|
if (tb_cap_is_long(&header)) {
|
|
/* tb_cap_extended_long is 2 dwords */
|
|
res = tb_port_read(port, &header, space,
|
|
offset, 2);
|
|
if (res)
|
|
return res;
|
|
}
|
|
}
|
|
offset = tb_cap_next(&header, offset);
|
|
if (!offset)
|
|
return 0;
|
|
}
|
|
tb_port_WARN(port,
|
|
"run out of retries while looking for cap %#x in config space %d, last offset: %#x\n",
|
|
cap, space, offset);
|
|
return -EIO;
|
|
}
|