163 lines
4.5 KiB
Diff
163 lines
4.5 KiB
Diff
From: Andreas Noever <andreas.noever@gmail.com>
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Date: Tue, 3 Jun 2014 22:04:03 +0200
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Subject: [06/31] thunderbolt: Add thunderbolt capability handling
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Origin: https://git.kernel.org/linus/e2b8785ed312dad3a18279a3e88435fc269658c1
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Thunderbolt config areas contain capability lists similar to those found
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on pci devices. This patch introduces a tb_find_cap utility method to
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search for capabilities.
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Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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drivers/thunderbolt/Makefile | 2 +-
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drivers/thunderbolt/cap.c | 116 +++++++++++++++++++++++++++++++++++++++++++
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drivers/thunderbolt/tb.h | 2 +
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3 files changed, 119 insertions(+), 1 deletion(-)
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create mode 100644 drivers/thunderbolt/cap.c
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diff --git a/drivers/thunderbolt/Makefile b/drivers/thunderbolt/Makefile
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index 4ac18d9..617b314 100644
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--- a/drivers/thunderbolt/Makefile
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+++ b/drivers/thunderbolt/Makefile
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@@ -1,3 +1,3 @@
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obj-${CONFIG_THUNDERBOLT} := thunderbolt.o
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-thunderbolt-objs := nhi.o ctl.o tb.o switch.o
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+thunderbolt-objs := nhi.o ctl.o tb.o switch.o cap.o
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diff --git a/drivers/thunderbolt/cap.c b/drivers/thunderbolt/cap.c
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new file mode 100644
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index 0000000..a7b47e7
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--- /dev/null
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+++ b/drivers/thunderbolt/cap.c
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@@ -0,0 +1,116 @@
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+/*
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+ * Thunderbolt Cactus Ridge driver - capabilities lookup
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+ *
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+ * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
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+ */
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+
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+#include <linux/slab.h>
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+#include <linux/errno.h>
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+
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+#include "tb.h"
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+
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+
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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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+
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+static bool tb_cap_is_basic(struct tb_cap_any *cap)
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+{
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+ /* basic.cap is u8. This checks only the lower 8 bit of cap. */
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+ return cap->basic.cap != 5;
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+}
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+
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+static bool tb_cap_is_long(struct tb_cap_any *cap)
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+{
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+ return !tb_cap_is_basic(cap)
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+ && cap->extended_short.next == 0
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+ && cap->extended_short.length == 0;
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+}
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+
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+static enum tb_cap tb_cap(struct tb_cap_any *cap)
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+{
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+ if (tb_cap_is_basic(cap))
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+ return cap->basic.cap;
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+ else
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+ /* extended_short/long have cap at the same offset. */
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+ return cap->extended_short.cap;
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+}
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+
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+static u32 tb_cap_next(struct tb_cap_any *cap, u32 offset)
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+{
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+ int next;
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+ if (offset == 1) {
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+ /*
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+ * The first pointer is part of the switch header and always
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+ * a simple pointer.
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+ */
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+ next = cap->basic.next;
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+ } else {
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+ /*
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+ * Somehow Intel decided to use 3 different types of capability
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+ * headers. It is not like anyone could have predicted that
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+ * single byte offsets are not enough...
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+ */
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+ if (tb_cap_is_basic(cap))
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+ next = cap->basic.next;
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+ else if (!tb_cap_is_long(cap))
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+ next = cap->extended_short.next;
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+ else
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+ next = cap->extended_long.next;
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+ }
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+ /*
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+ * "Hey, we could terminate some capability lists with a null offset
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+ * and others with a pointer to the last element." - "Great idea!"
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+ */
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+ if (next == offset)
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+ return 0;
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+ return next;
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+}
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+
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+/**
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+ * tb_find_cap() - find a capability
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+ *
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+ * Return: Returns a positive offset if the capability was found and 0 if not.
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+ * Returns an error code on failure.
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+ */
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+int tb_find_cap(struct tb_port *port, enum tb_cfg_space space, enum tb_cap cap)
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+{
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+ u32 offset = 1;
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+ struct tb_cap_any header;
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+ int res;
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+ int retries = 10;
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+ while (retries--) {
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+ res = tb_port_read(port, &header, space, offset, 1);
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+ if (res) {
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+ /* Intel needs some help with linked lists. */
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+ if (space == TB_CFG_PORT && offset == 0xa
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+ && port->config.type == TB_TYPE_DP_HDMI_OUT) {
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+ offset = 0x39;
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+ continue;
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+ }
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+ return res;
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+ }
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+ if (offset != 1) {
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+ if (tb_cap(&header) == cap)
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+ return offset;
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+ if (tb_cap_is_long(&header)) {
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+ /* tb_cap_extended_long is 2 dwords */
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+ res = tb_port_read(port, &header, space,
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+ offset, 2);
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+ if (res)
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+ return res;
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+ }
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+ }
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+ offset = tb_cap_next(&header, offset);
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+ if (!offset)
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+ return 0;
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+ }
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+ tb_port_WARN(port,
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+ "run out of retries while looking for cap %#x in config space %d, last offset: %#x\n",
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+ cap, space, offset);
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+ return -EIO;
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+}
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diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
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index 389dbb4..38e4c23 100644
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--- a/drivers/thunderbolt/tb.h
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+++ b/drivers/thunderbolt/tb.h
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@@ -159,6 +159,8 @@ void thunderbolt_shutdown_and_free(struct tb *tb);
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struct tb_switch *tb_switch_alloc(struct tb *tb, u64 route);
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void tb_switch_free(struct tb_switch *sw);
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+int tb_find_cap(struct tb_port *port, enum tb_cfg_space space, u32 value);
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+
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static inline int tb_route_length(u64 route)
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{
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