diff options
| -rw-r--r-- | drivers/thunderbolt/Makefile | 2 | ||||
| -rw-r--r-- | drivers/thunderbolt/cap.c | 116 | ||||
| -rw-r--r-- | drivers/thunderbolt/tb.h | 2 |
3 files changed, 119 insertions, 1 deletions
diff --git a/drivers/thunderbolt/Makefile b/drivers/thunderbolt/Makefile index 4ac18d969306..617b31480b2e 100644 --- a/drivers/thunderbolt/Makefile +++ b/drivers/thunderbolt/Makefile @@ -1,3 +1,3 @@ obj-${CONFIG_THUNDERBOLT} := thunderbolt.o -thunderbolt-objs := nhi.o ctl.o tb.o switch.o +thunderbolt-objs := nhi.o ctl.o tb.o switch.o cap.o diff --git a/drivers/thunderbolt/cap.c b/drivers/thunderbolt/cap.c new file mode 100644 index 000000000000..a7b47e7cddbd --- /dev/null +++ b/drivers/thunderbolt/cap.c @@ -0,0 +1,116 @@ +/* + * 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; +} diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h index 389dbb405c5f..38e4c23c10fd 100644 --- a/drivers/thunderbolt/tb.h +++ b/drivers/thunderbolt/tb.h @@ -159,6 +159,8 @@ void thunderbolt_shutdown_and_free(struct tb *tb); struct tb_switch *tb_switch_alloc(struct tb *tb, u64 route); void tb_switch_free(struct tb_switch *sw); +int tb_find_cap(struct tb_port *port, enum tb_cfg_space space, u32 value); + static inline int tb_route_length(u64 route) { |