thunderbolt: Set sleep bit when suspending switch

Thunderbolt 2 devices and beyond link controller needs to be notified
when a switch is going to be suspended by setting bit 31 in LC_SX_CTRL
register. Add this functionality to the software connection manager.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/lc.c

@@ -133,3 +133,47 @@ void tb_lc_unconfigure_link(struct tb_switch *sw)
 	tb_lc_configure_lane(up, false);
 	tb_lc_configure_lane(down, false);
 }
+
+/**
+ * tb_lc_set_sleep() - Inform LC that the switch is going to sleep
+ * @sw: Switch to set sleep
+ *
+ * Let the switch link controllers know that the switch is going to
+ * sleep.
+ */
+int tb_lc_set_sleep(struct tb_switch *sw)
+{
+	int start, size, nlc, ret, i;
+	u32 desc;
+
+	if (sw->generation < 2)
+		return 0;
+
+	ret = read_lc_desc(sw, &desc);
+	if (ret)
+		return ret;
+
+	/* Figure out number of link controllers */
+	nlc = desc & TB_LC_DESC_NLC_MASK;
+	start = (desc & TB_LC_DESC_SIZE_MASK) >> TB_LC_DESC_SIZE_SHIFT;
+	size = (desc & TB_LC_DESC_PORT_SIZE_MASK) >> TB_LC_DESC_PORT_SIZE_SHIFT;
+
+	/* For each link controller set sleep bit */
+	for (i = 0; i < nlc; i++) {
+		unsigned int offset = sw->cap_lc + start + i * size;
+		u32 ctrl;
+
+		ret = tb_sw_read(sw, &ctrl, TB_CFG_SWITCH,
+				 offset + TB_LC_SX_CTRL, 1);
+		if (ret)
+			return ret;
+
+		ctrl |= TB_LC_SX_CTRL_SLP;
+		ret = tb_sw_write(sw, &ctrl, TB_CFG_SWITCH,
+				  offset + TB_LC_SX_CTRL, 1);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}

drivers/thunderbolt/switch.c

@@ -1586,10 +1586,8 @@ void tb_switch_suspend(struct tb_switch *sw)
 		if (!tb_is_upstream_port(&sw->ports[i]) && sw->ports[i].remote)
 			tb_switch_suspend(sw->ports[i].remote->sw);
 	}
-	/*
-	 * TODO: invoke tb_cfg_prepare_to_sleep here? does not seem to have any
-	 * effect?
-	 */
+
+	tb_lc_set_sleep(sw);
 }
 
 struct tb_sw_lookup {

drivers/thunderbolt/tb.h

@@ -467,6 +467,7 @@ int tb_drom_read_uid_only(struct tb_switch *sw, u64 *uid);
 int tb_lc_read_uuid(struct tb_switch *sw, u32 *uuid);
 int tb_lc_configure_link(struct tb_switch *sw);
 void tb_lc_unconfigure_link(struct tb_switch *sw);
+int tb_lc_set_sleep(struct tb_switch *sw);
 
 static inline int tb_route_length(u64 route)
 {

drivers/thunderbolt/tb_regs.h

@@ -239,6 +239,7 @@ struct tb_regs_hop {
 
 /* Common link controller registers */
 #define TB_LC_DESC			0x02
+#define TB_LC_DESC_NLC_MASK		GENMASK(3, 0)
 #define TB_LC_DESC_SIZE_SHIFT		8
 #define TB_LC_DESC_SIZE_MASK		GENMASK(15, 8)
 #define TB_LC_DESC_PORT_SIZE_SHIFT	16
@@ -250,5 +251,6 @@ struct tb_regs_hop {
 #define TB_LC_SX_CTRL_L1C		BIT(16)
 #define TB_LC_SX_CTRL_L2C		BIT(20)
 #define TB_LC_SX_CTRL_UPSTREAM		BIT(30)
+#define TB_LC_SX_CTRL_SLP		BIT(31)
 
 #endif