1 files changed, 91 insertions, 78 deletions

diff --git a/drivers/thunderbolt/cap.c b/drivers/thunderbolt/cap.c
index a7b47e7cddbd..38bc27a5ce4f 100644
--- a/drivers/thunderbolt/cap.c
+++ b/drivers/thunderbolt/cap.c
@@ -9,6 +9,8 @@
 
 #include "tb.h"
 
+#define CAP_OFFSET_MAX		0xff
+#define VSE_CAP_OFFSET_MAX	0xffff
 
 struct tb_cap_any {
 	union {
@@ -18,99 +20,110 @@ struct tb_cap_any {
 	};
 } __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)
+/**
+ * tb_port_find_cap() - Find port capability
+ * @port: Port to find the capability for
+ * @cap: Capability to look
+ *
+ * Returns offset to start of capability or %-ENOENT if no such
+ * capability was found. Negative errno is returned if there was an
+ * error.
+ */
+int tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
 {
-	return !tb_cap_is_basic(cap)
-	       && cap->extended_short.next == 0
-	       && cap->extended_short.length == 0;
-}
+	u32 offset;
 
-static enum tb_cap tb_cap(struct tb_cap_any *cap)
-{
-	if (tb_cap_is_basic(cap))
-		return cap->basic.cap;
+	/*
+	 * DP out adapters claim to implement TMU capability but in
+	 * reality they do not so we hard code the adapter specific
+	 * capability offset here.
+	 */
+	if (port->config.type == TB_TYPE_DP_HDMI_OUT)
+		offset = 0x39;
 	else
-		/* extended_short/long have cap at the same offset. */
-		return cap->extended_short.cap;
+		offset = 0x1;
+
+	do {
+		struct tb_cap_any header;
+		int ret;
+
+		ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);
+		if (ret)
+			return ret;
+
+		if (header.basic.cap == cap)
+			return offset;
+
+		offset = header.basic.next;
+	} while (offset);
+
+	return -ENOENT;
 }
 
-static u32 tb_cap_next(struct tb_cap_any *cap, u32 offset)
+static int tb_switch_find_cap(struct tb_switch *sw, enum tb_switch_cap cap)
 {
-	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;
+	int offset = sw->config.first_cap_offset;
+
+	while (offset > 0 && offset < CAP_OFFSET_MAX) {
+		struct tb_cap_any header;
+		int ret;
+
+		ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1);
+		if (ret)
+			return ret;
+
+		if (header.basic.cap == cap)
+			return offset;
+
+		offset = header.basic.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;
+
+	return -ENOENT;
 }
 
 /**
- * tb_find_cap() - find a capability
+ * tb_switch_find_vse_cap() - Find switch vendor specific capability
+ * @sw: Switch to find the capability for
+ * @vsec: Vendor specific capability to look
  *
- * Return: Returns a positive offset if the capability was found and 0 if not.
- * Returns an error code on failure.
+ * Functions enumerates vendor specific capabilities (VSEC) of a switch
+ * and returns offset when capability matching @vsec is found. If no
+ * such capability is found returns %-ENOENT. In case of error returns
+ * negative errno.
  */
-int tb_find_cap(struct tb_port *port, enum tb_cfg_space space, enum tb_cap cap)
+int tb_switch_find_vse_cap(struct tb_switch *sw, enum tb_switch_vse_cap vsec)
 {
-	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)
+	int offset;
+
+	offset = tb_switch_find_cap(sw, TB_SWITCH_CAP_VSE);
+	if (offset < 0)
+		return offset;
+
+	while (offset > 0 && offset < VSE_CAP_OFFSET_MAX) {
+		int ret;
+
+		ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 2);
+		if (ret)
+			return ret;
+
+		/*
+		 * Extended vendor specific capabilities come in two
+		 * flavors: short and long. The latter is used when
+		 * offset is over 0xff.
+		 */
+		if (offset >= CAP_OFFSET_MAX) {
+			if (header.extended_long.vsec_id == vsec)
 				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 = header.extended_long.next;
+		} else {
+			if (header.extended_short.vsec_id == vsec)
+				return offset;
+			if (!header.extended_short.length)
+				return -ENOENT;
+			offset = header.extended_short.next;
 		}
-		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;
+
+	return -ENOENT;
 }