thunderbolt: Add DisplayPort 2.x tunneling support

This adds support for the UHBR (Ultra High Bit Rate) bandwidths
introduced with DisplayPort 2.0 (and refined in 2.1). These can go up to
80 Gbit/s and their support is represent in additional bits in the DP IN
capability.

This updates the DisplayPort tunneling to support these new rates too.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/tb_regs.h

@@ -450,6 +450,9 @@ struct tb_regs_port_header {
 #define DP_COMMON_CAP_1_LANE			0x0
 #define DP_COMMON_CAP_2_LANES			0x1
 #define DP_COMMON_CAP_4_LANES			0x2
+#define DP_COMMON_CAP_UHBR10			BIT(17)
+#define DP_COMMON_CAP_UHBR20			BIT(18)
+#define DP_COMMON_CAP_UHBR13_5			BIT(19)
 #define DP_COMMON_CAP_LTTPR_NS			BIT(27)
 #define DP_COMMON_CAP_BW_MODE			BIT(28)
 #define DP_COMMON_CAP_DPRX_DONE			BIT(31)

drivers/thunderbolt/tunnel.c

@@ -418,6 +418,10 @@ static int tb_dp_cm_handshake(struct tb_port *in, struct tb_port *out,
 	return -ETIMEDOUT;
 }
 
+/*
+ * Returns maximum possible rate from capability supporting only DP 2.0
+ * and below. Used when DP BW allocation mode is not enabled.
+ */
 static inline u32 tb_dp_cap_get_rate(u32 val)
 {
 	u32 rate = (val & DP_COMMON_CAP_RATE_MASK) >> DP_COMMON_CAP_RATE_SHIFT;
@@ -436,6 +440,28 @@ static inline u32 tb_dp_cap_get_rate(u32 val)
 	}
 }
 
+/*
+ * Returns maximum possible rate from capability supporting DP 2.1
+ * UHBR20, 13.5 and 10 rates as well. Use only when DP BW allocation
+ * mode is enabled.
+ */
+static inline u32 tb_dp_cap_get_rate_ext(u32 val)
+{
+	if (val & DP_COMMON_CAP_UHBR20)
+		return 20000;
+	else if (val & DP_COMMON_CAP_UHBR13_5)
+		return 13500;
+	else if (val & DP_COMMON_CAP_UHBR10)
+		return 10000;
+
+	return tb_dp_cap_get_rate(val);
+}
+
+static inline bool tb_dp_is_uhbr_rate(unsigned int rate)
+{
+	return rate >= 10000;
+}
+
 static inline u32 tb_dp_cap_set_rate(u32 val, u32 rate)
 {
 	val &= ~DP_COMMON_CAP_RATE_MASK;
@@ -498,7 +524,9 @@ static inline u32 tb_dp_cap_set_lanes(u32 val, u32 lanes)
 
 static unsigned int tb_dp_bandwidth(unsigned int rate, unsigned int lanes)
 {
-	/* Tunneling removes the DP 8b/10b encoding */
+	/* Tunneling removes the DP 8b/10b 128/132b encoding */
+	if (tb_dp_is_uhbr_rate(rate))
+		return rate * lanes * 128 / 132;
 	return rate * lanes * 8 / 10;
 }
 
@@ -691,6 +719,19 @@ static int tb_dp_bandwidth_alloc_mode_enable(struct tb_tunnel *tunnel)
 	if (ret)
 		return ret;
 
+	/*
+	 * Pick up granularity that supports maximum possible bandwidth.
+	 * For that we use the UHBR rates too.
+	 */
+	in_rate = tb_dp_cap_get_rate_ext(in_dp_cap);
+	out_rate = tb_dp_cap_get_rate_ext(out_dp_cap);
+	rate = min(in_rate, out_rate);
+	tmp = tb_dp_bandwidth(rate, lanes);
+
+	tb_port_dbg(in,
+		    "maximum bandwidth through allocation mode %u Mb/s x%u = %u Mb/s\n",
+		    rate, lanes, tmp);
+
 	for (granularity = 250; tmp / granularity > 255 && granularity <= 1000;
 	     granularity *= 2)
 		;
@@ -806,15 +847,42 @@ static int tb_dp_activate(struct tb_tunnel *tunnel, bool active)
 }
 
 /* max_bw is rounded up to next granularity */
-static int tb_dp_nrd_bandwidth(struct tb_tunnel *tunnel, int *max_bw)
+static int tb_dp_bandwidth_mode_maximum_bandwidth(struct tb_tunnel *tunnel,
+						  int *max_bw)
 {
 	struct tb_port *in = tunnel->src_port;
 	int ret, rate, lanes, nrd_bw;
+	u32 cap;
 
-	ret = usb4_dp_port_nrd(in, &rate, &lanes);
+	/*
+	 * DP IN adapter DP_LOCAL_CAP gets updated to the lowest AUX
+	 * read parameter values so this so we can use this to determine
+	 * the maximum possible bandwidth over this link.
+	 *
+	 * See USB4 v2 spec 1.0 10.4.4.5.
+	 */
+	ret = tb_port_read(in, &cap, TB_CFG_PORT,
+			   in->cap_adap + DP_LOCAL_CAP, 1);
 	if (ret)
 		return ret;
 
+	rate = tb_dp_cap_get_rate_ext(cap);
+	if (tb_dp_is_uhbr_rate(rate)) {
+		/*
+		 * When UHBR is used there is no reduction in lanes so
+		 * we can use this directly.
+		 */
+		lanes = tb_dp_cap_get_lanes(cap);
+	} else {
+		/*
+		 * If there is no UHBR supported then check the
+		 * non-reduced rate and lanes.
+		 */
+		ret = usb4_dp_port_nrd(in, &rate, &lanes);
+		if (ret)
+			return ret;
+	}
+
 	nrd_bw = tb_dp_bandwidth(rate, lanes);
 
 	if (max_bw) {
@@ -847,7 +915,7 @@ static int tb_dp_bandwidth_mode_consumed_bandwidth(struct tb_tunnel *tunnel,
 		return ret;
 	allocated_bw = ret;
 
-	ret = tb_dp_nrd_bandwidth(tunnel, &max_bw);
+	ret = tb_dp_bandwidth_mode_maximum_bandwidth(tunnel, &max_bw);
 	if (ret < 0)
 		return ret;
 	if (allocated_bw == max_bw)
@@ -885,7 +953,7 @@ static int tb_dp_allocated_bandwidth(struct tb_tunnel *tunnel, int *allocated_up
 			return ret;
 		allocated_bw = ret;
 
-		ret = tb_dp_nrd_bandwidth(tunnel, &max_bw);
+		ret = tb_dp_bandwidth_mode_maximum_bandwidth(tunnel, &max_bw);
 		if (ret < 0)
 			return ret;
 		if (allocated_bw == max_bw)
@@ -915,7 +983,7 @@ static int tb_dp_alloc_bandwidth(struct tb_tunnel *tunnel, int *alloc_up,
 	if (!usb4_dp_port_bandwidth_mode_enabled(in))
 		return -EOPNOTSUPP;
 
-	ret = tb_dp_nrd_bandwidth(tunnel, &max_bw);
+	ret = tb_dp_bandwidth_mode_maximum_bandwidth(tunnel, &max_bw);
 	if (ret < 0)
 		return ret;
 
@@ -938,6 +1006,9 @@ static int tb_dp_alloc_bandwidth(struct tb_tunnel *tunnel, int *alloc_up,
 	/* Now we can use BW mode registers to figure out the bandwidth */
 	/* TODO: need to handle discovery too */
 	tunnel->bw_mode = true;
+
+	tb_port_dbg(in, "allocated bandwidth through allocation mode %d Mb/s\n",
+		    tmp);
 	return 0;
 }
 
@@ -1012,23 +1083,20 @@ static int tb_dp_maximum_bandwidth(struct tb_tunnel *tunnel, int *max_up,
 				   int *max_down)
 {
 	struct tb_port *in = tunnel->src_port;
-	u32 rate, lanes;
 	int ret;
 
-	/*
-	 * DP IN adapter DP_LOCAL_CAP gets updated to the lowest AUX read
-	 * parameter values so this so we can use this to determine the
-	 * maximum possible bandwidth over this link.
-	 */
-	ret = tb_dp_read_cap(tunnel, DP_LOCAL_CAP, &rate, &lanes);
-	if (ret)
+	if (!usb4_dp_port_bandwidth_mode_enabled(in))
+		return -EOPNOTSUPP;
+
+	ret = tb_dp_bandwidth_mode_maximum_bandwidth(tunnel, NULL);
+	if (ret < 0)
 		return ret;
 
 	if (in->sw->config.depth < tunnel->dst_port->sw->config.depth) {
 		*max_up = 0;
-		*max_down = tb_dp_bandwidth(rate, lanes);
+		*max_down = ret;
 	} else {
-		*max_up = tb_dp_bandwidth(rate, lanes);
+		*max_up = ret;
 		*max_down = 0;
 	}