thunderbolt: Explicitly enable lane adapter hotplug events at startup

Software that has run before the USB4 CM in Linux runs may have disabled
hotplug events for a given lane adapter.

Other CMs such as that one distributed with Windows 11 will enable hotplug
events. Do the same thing in the Linux CM which fixes hotplug events on
"AMD Pink Sardine".

Cc: stable@vger.kernel.org
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/switch.c

@@ -2900,6 +2900,26 @@ static void tb_switch_credits_init(struct tb_switch *sw)
 		tb_sw_info(sw, "failed to determine preferred buffer allocation, using defaults\n");
 }
 
+static int tb_switch_port_hotplug_enable(struct tb_switch *sw)
+{
+	struct tb_port *port;
+
+	if (tb_switch_is_icm(sw))
+		return 0;
+
+	tb_switch_for_each_port(sw, port) {
+		int res;
+
+		if (!port->cap_usb4)
+			continue;
+
+		res = usb4_port_hotplug_enable(port);
+		if (res)
+			return res;
+	}
+	return 0;
+}
+
 /**
  * tb_switch_add() - Add a switch to the domain
  * @sw: Switch to add
@@ -2969,6 +2989,10 @@ int tb_switch_add(struct tb_switch *sw)
 			return ret;
 	}
 
+	ret = tb_switch_port_hotplug_enable(sw);
+	if (ret)
+		return ret;
+
 	ret = device_add(&sw->dev);
 	if (ret) {
 		dev_err(&sw->dev, "failed to add device: %d\n", ret);

drivers/thunderbolt/tb.h

@@ -1194,6 +1194,7 @@ int usb4_switch_add_ports(struct tb_switch *sw);
 void usb4_switch_remove_ports(struct tb_switch *sw);
 
 int usb4_port_unlock(struct tb_port *port);
+int usb4_port_hotplug_enable(struct tb_port *port);
 int usb4_port_configure(struct tb_port *port);
 void usb4_port_unconfigure(struct tb_port *port);
 int usb4_port_configure_xdomain(struct tb_port *port);

drivers/thunderbolt/tb_regs.h

@@ -308,6 +308,7 @@ struct tb_regs_port_header {
 #define ADP_CS_5				0x05
 #define ADP_CS_5_LCA_MASK			GENMASK(28, 22)
 #define ADP_CS_5_LCA_SHIFT			22
+#define ADP_CS_5_DHP				BIT(31)
 
 /* TMU adapter registers */
 #define TMU_ADP_CS_3				0x03

drivers/thunderbolt/usb4.c

@@ -1046,6 +1046,26 @@ int usb4_port_unlock(struct tb_port *port)
 	return tb_port_write(port, &val, TB_CFG_PORT, ADP_CS_4, 1);
 }
 
+/**
+ * usb4_port_hotplug_enable() - Enables hotplug for a port
+ * @port: USB4 port to operate on
+ *
+ * Enables hot plug events on a given port. This is only intended
+ * to be used on lane, DP-IN, and DP-OUT adapters.
+ */
+int usb4_port_hotplug_enable(struct tb_port *port)
+{
+	int ret;
+	u32 val;
+
+	ret = tb_port_read(port, &val, TB_CFG_PORT, ADP_CS_5, 1);
+	if (ret)
+		return ret;
+
+	val &= ~ADP_CS_5_DHP;
+	return tb_port_write(port, &val, TB_CFG_PORT, ADP_CS_5, 1);
+}
+
 static int usb4_port_set_configured(struct tb_port *port, bool configured)
 {
 	int ret;