thunderbolt: Cache adapter specific capability offset into struct port

The adapter specific capability either is there or not if the port does
not hold an adapter. Instead of always finding it on-demand we read the
offset just once when the port is initialized.

While there we update the struct port documentation to follow kernel-doc
format.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/switch.c

@@ -586,6 +586,10 @@ static int tb_init_port(struct tb_port *port)
 			port->cap_phy = cap;
 		else
 			tb_port_WARN(port, "non switch port without a PHY\n");
+	} else if (port->port != 0) {
+		cap = tb_port_find_cap(port, TB_PORT_CAP_ADAP);
+		if (cap > 0)
+			port->cap_adap = cap;
 	}
 
 	tb_dump_port(port->sw->tb, &port->config);

drivers/thunderbolt/tb.c

@@ -151,8 +151,8 @@ static struct tb_port *tb_find_unused_down_port(struct tb_switch *sw)
 			continue;
 		if (sw->ports[i].config.type != TB_TYPE_PCIE_DOWN)
 			continue;
-		cap = tb_port_find_cap(&sw->ports[i], TB_PORT_CAP_ADAP);
-		if (cap < 0)
+		cap = sw->ports[i].cap_adap;
+		if (!cap)
 			continue;
 		res = tb_port_read(&sw->ports[i], &data, TB_CFG_PORT, cap, 1);
 		if (res < 0)
@@ -197,8 +197,8 @@ static void tb_activate_pcie_devices(struct tb *tb)
 		}
 
 		/* check whether port is already activated */
-		cap = tb_port_find_cap(up_port, TB_PORT_CAP_ADAP);
-		if (cap < 0)
+		cap = up_port->cap_adap;
+		if (!cap)
 			continue;
 		if (tb_port_read(up_port, &data, TB_CFG_PORT, cap, 1))
 			continue;

drivers/thunderbolt/tb.h

@@ -121,6 +121,7 @@ struct tb_switch {
  * @remote: Remote port (%NULL if not connected)
  * @xdomain: Remote host (%NULL if not connected)
  * @cap_phy: Offset, zero if not found
+ * @cap_adap: Offset of the adapter specific capability (%0 if not present)
  * @port: Port number on switch
  * @disabled: Disabled by eeprom
  * @dual_link_port: If the switch is connected using two ports, points
@@ -133,6 +134,7 @@ struct tb_port {
 	struct tb_port *remote;
 	struct tb_xdomain *xdomain;
 	int cap_phy;
+	int cap_adap;
 	u8 port;
 	bool disabled;
 	struct tb_port *dual_link_port;

drivers/thunderbolt/tunnel_pci.c

@@ -148,12 +148,9 @@ bool tb_pci_is_invalid(struct tb_pci_tunnel *tunnel)
 static int tb_pci_port_active(struct tb_port *port, bool active)
 {
 	u32 word = active ? 0x80000000 : 0x0;
-	int cap = tb_port_find_cap(port, TB_PORT_CAP_ADAP);
-	if (cap < 0) {
-		tb_port_warn(port, "TB_PORT_CAP_ADAP not found: %d\n", cap);
-		return cap;
-	}
-	return tb_port_write(port, &word, TB_CFG_PORT, cap, 1);
+	if (!port->cap_adap)
+		return -ENXIO;
+	return tb_port_write(port, &word, TB_CFG_PORT, port->cap_adap, 1);
 }
 
 /**