thunderbolt: Add receiver lane margining support for retimers

Retimers support lane margining as well so make this available through
debugfs in the same way as we do for the USB4 ports. When this is
enabled we also expose retimers on the other side of the cable because
typically margining is implemented only on direction towards the cable.
However, for the retimers on the other side of the cable we do not allow
NVM upgrade to avoid confusing the existing userspace (the same retimer
may now appear twice with different name) and is probably not a good
idea anyway.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 26 insertions, 17 deletions

diff --git a/drivers/thunderbolt/retimer.c b/drivers/thunderbolt/retimer.c
index 8ce1dc7bbfad..721319329afa 100644
--- a/drivers/thunderbolt/retimer.c
+++ b/drivers/thunderbolt/retimer.c
@@ -14,7 +14,11 @@
 #include "sb_regs.h"
 #include "tb.h"
 
+#if IS_ENABLED(CONFIG_USB4_DEBUGFS_MARGINING)
 #define TB_MAX_RETIMER_INDEX	6
+#else
+#define TB_MAX_RETIMER_INDEX	2
+#endif
 
 /**
  * tb_retimer_nvm_read() - Read contents of retimer NVM
@@ -319,6 +323,8 @@ static ssize_t nvm_version_show(struct device *dev,
 
 	if (!rt->nvm)
 		ret = -EAGAIN;
+	else if (rt->no_nvm_upgrade)
+		ret = -EOPNOTSUPP;
 	else
 		ret = sysfs_emit(buf, "%x.%x\n", rt->nvm->major, rt->nvm->minor);
 
@@ -366,7 +372,8 @@ const struct device_type tb_retimer_type = {
 	.release = tb_retimer_release,
 };
 
-static int tb_retimer_add(struct tb_port *port, u8 index, u32 auth_status)
+static int tb_retimer_add(struct tb_port *port, u8 index, u32 auth_status,
+			  bool on_board)
 {
 	struct tb_retimer *rt;
 	u32 vendor, device;
@@ -388,13 +395,6 @@ static int tb_retimer_add(struct tb_port *port, u8 index, u32 auth_status)
 		return ret;
 	}
 
-	/*
-	 * Check that it supports NVM operations. If not then don't add
-	 * the device at all.
-	 */
-	ret = usb4_port_retimer_nvm_sector_size(port, index);
-	if (ret < 0)
-		return ret;
 
 	rt = kzalloc(sizeof(*rt), GFP_KERNEL);
 	if (!rt)
@@ -407,6 +407,13 @@ static int tb_retimer_add(struct tb_port *port, u8 index, u32 auth_status)
 	rt->port = port;
 	rt->tb = port->sw->tb;
 
+	/*
+	 * Only support NVM upgrade for on-board retimers. The retimers
+	 * on the other side of the connection.
+	 */
+	if (!on_board || usb4_port_retimer_nvm_sector_size(port, index) <= 0)
+		rt->no_nvm_upgrade = true;
+
 	rt->dev.parent = &port->usb4->dev;
 	rt->dev.bus = &tb_bus_type;
 	rt->dev.type = &tb_retimer_type;
@@ -487,7 +494,7 @@ static struct tb_retimer *tb_port_find_retimer(struct tb_port *port, u8 index)
 int tb_retimer_scan(struct tb_port *port, bool add)
 {
 	u32 status[TB_MAX_RETIMER_INDEX + 1] = {};
-	int ret, i, last_idx = 0;
+	int ret, i, max, last_idx = 0;
 
 	/*
 	 * Send broadcast RT to make sure retimer indices facing this
@@ -522,26 +529,28 @@ int tb_retimer_scan(struct tb_port *port, bool add)
 			break;
 	}
 
-	tb_retimer_unset_inbound_sbtx(port);
-
-	if (!last_idx)
-		return 0;
-
-	/* Add on-board retimers if they do not exist already */
+	max = i;
 	ret = 0;
-	for (i = 1; i <= last_idx; i++) {
+
+	/* Add retimers if they do not exist already */
+	for (i = 1; i <= max; i++) {
 		struct tb_retimer *rt;
 
+		/* Skip cable retimers */
+		if (usb4_port_retimer_is_cable(port, i))
+			continue;
+
 		rt = tb_port_find_retimer(port, i);
 		if (rt) {
 			put_device(&rt->dev);
 		} else if (add) {
-			ret = tb_retimer_add(port, i, status[i]);
+			ret = tb_retimer_add(port, i, status[i], i <= last_idx);
 			if (ret && ret != -EOPNOTSUPP)
 				break;
 		}
 	}
 
+	tb_retimer_unset_inbound_sbtx(port);
 	return ret;
 }