Messages in this thread Patch in this message | | | From | Andreas Noever <> | Subject | [PATCH 06/12] thunderbolt: Add thunderbolt capability handling | Date | Fri, 29 Nov 2013 02:35:43 +0100 |
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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> --- drivers/thunderbolt/tb.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++ drivers/thunderbolt/tb.h | 2 + 2 files changed, 105 insertions(+)
diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c index d2df3be..943842b 100644 --- a/drivers/thunderbolt/tb.c +++ b/drivers/thunderbolt/tb.c @@ -89,6 +89,109 @@ static int tb_route_length(u64 route) return (fls64(route) + TB_ROUTE_SHIFT - 1) / TB_ROUTE_SHIFT; } + +/* thunderbolt capability lookup */ + +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 position. */ + 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 { + if (tb_cap_is_basic(cap)) + next = cap->basic.next; + /* "255 byte config areas should be enough for anybody." */ + else if (!tb_cap_is_long(cap)) + next = cap->extended_short.next; + /* + * "Also we should have at least three types of capability + * headers in version 1." + */ + 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 && tb_cap(&header) == cap) + return offset; + offset = tb_cap_next(&header, offset); + if (!offset) + return 0; + continue; + } + tb_port_WARN(port, + "could not find cap %#x in config space %d, last offset: %#x\n", + cap, + space, + offset); + return -EIO; +} + /* switch/port allocation & initialization */ /** diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h index 4000f2b..e81c63a 100644 --- a/drivers/thunderbolt/tb.h +++ b/drivers/thunderbolt/tb.h @@ -144,4 +144,6 @@ static inline int tb_port_write(struct tb_port *port, void *buffer, struct tb *thunderbolt_alloc_and_start(struct tb_nhi *nhi); void thunderbolt_shutdown_and_free(struct tb *tb); +int tb_find_cap(struct tb_port *port, enum tb_cfg_space space, u32 value); + #endif -- 1.8.4.2
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