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authorLinus Torvalds <torvalds@linux-foundation.org>2014-08-04 17:32:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-04 17:32:24 -0700
commit2521129a6d2fd8a81f99cf95055eddea3df914ff (patch)
treef8b7879979f656669ce31cbc247b97ae702291fb /drivers/thunderbolt/cap.c
parent98a96f202203fecad65b44449077c695686ad4db (diff)
parent16eb2bfc65ef86d3ac6420d50ddc2c48f0023cee (diff)
Merge tag 'char-misc-3.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char / misc driver patches from Greg KH: "Here's the big driver misc / char pull request for 3.17-rc1. Lots of things in here, the thunderbolt support for Apple laptops, some other new drivers, testing fixes, and other good things. All have been in linux-next for a long time" * tag 'char-misc-3.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (119 commits) misc: bh1780: Introduce the use of devm_kzalloc Lattice ECP3 FPGA: Correct endianness drivers/misc/ti-st: Load firmware from ti-connectivity directory. dt-bindings: extcon: Add support for SM5502 MUIC device extcon: sm5502: Change internal hardware switch according to cable type extcon: sm5502: Detect cable state after completing platform booting extcon: sm5502: Add support new SM5502 extcon device driver extcon: arizona: Get MICVDD against extcon device extcon: Remove unnecessary OOM messages misc: vexpress: Fix sparse non static symbol warnings mei: drop unused hw dependent fw status functions misc: bh1770glc: Use managed functions pcmcia: remove DEFINE_PCI_DEVICE_TABLE usage misc: remove DEFINE_PCI_DEVICE_TABLE usage ipack: Replace DEFINE_PCI_DEVICE_TABLE macro use drivers/char/dsp56k.c: drop check for negativity of unsigned parameter mei: fix return value on disconnect timeout mei: don't schedule suspend in pm idle mei: start disconnect request timer consistently mei: reset client connection state on timeout ...
Diffstat (limited to 'drivers/thunderbolt/cap.c')
-rw-r--r--drivers/thunderbolt/cap.c116
1 files changed, 116 insertions, 0 deletions
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;
+}