@@ -92,6 +92,24 @@ static void mxl862xx_flash_notify(struct devlink *dl, const char *status,
 	devlink_flash_update_status_notify(dl, status, NULL, done, total);
 }
 
+/**
+ * mxl862xx_rescue_mode_detect - check whether the switch sits in MCUboot
+ * @priv: driver private data
+ *
+ * MCUboot signals readiness for a firmware download with the SB PDI
+ * ready magic; only the clause-22 SMDIO interface works in this state.
+ *
+ * Return: true if MCUboot is waiting for a firmware download.
+ */
+bool mxl862xx_rescue_mode_detect(struct mxl862xx_priv *priv)
+{
+	int ret;
+
+	ret = mxl862xx_smdio_read(priv, MXL862XX_SB_PDI_STAT);
+
+	return ret == MXL862XX_SB_PDI_READY;
+}
+
 /* device_reprobe() -> remove() frees priv while the work runs, so
  * the work struct cannot live in mxl862xx_priv.
  */

@@ -172,13 +190,15 @@ static int mxl862xx_flash_firmware(struct mxl862xx_priv *priv,
 	}
 
 	/* Step 1: reboot the firmware into MCUboot rescue mode */
-	ret = mxl862xx_api_wrap(priv, SYS_MISC_FW_UPDATE, NULL, 0,
-				false, false);
-	if (ret) {
-		dev_err(&priv->mdiodev->dev,
-			"flash: FW_UPDATE command failed: %pe\n",
-			ERR_PTR(ret));
-		return ret;
+	if (!priv->rescue_mode) {
+		ret = mxl862xx_api_wrap(priv, SYS_MISC_FW_UPDATE, NULL, 0,
+					false, false);
+		if (ret) {
+			dev_err(&priv->mdiodev->dev,
+				"flash: FW_UPDATE command failed: %pe\n",
+				ERR_PTR(ret));
+			return ret;
+		}
 	}
 
 	/* Failures from here on must go through end_magic so MCUboot

@@ -328,6 +348,10 @@ int mxl862xx_devlink_info_get(struct dsa_switch *ds,
 			return ret;
 	}
 
+	if (priv->rescue_mode)
+		return devlink_info_version_running_put(req, "fw",
+							"mcuboot-rescue");
+
 	snprintf(ver_str, sizeof(ver_str), "%u.%u.%u",
 		 priv->fw_version.major, priv->fw_version.minor,
 		 priv->fw_version.revision);

@@ -350,9 +374,13 @@ int mxl862xx_devlink_flash_update(struct dsa_switch *ds,
 		return -EOPNOTSUPP;
 	}
 
-	dev_info(ds->dev, "flash: running firmware %u.%u.%u\n",
-		 priv->fw_version.major, priv->fw_version.minor,
-		 priv->fw_version.revision);
+	if (priv->rescue_mode)
+		dev_info(ds->dev,
+			 "flash: recovering switch from MCUboot rescue mode\n");
+	else
+		dev_info(ds->dev, "flash: running firmware %u.%u.%u\n",
+			 priv->fw_version.major, priv->fw_version.minor,
+			 priv->fw_version.revision);
 
 	/* Close ports while the firmware is still alive so the DSA
 	 * core's MDB/FDB tracking is drained, and detach user ports

@@ -383,6 +411,7 @@ int mxl862xx_devlink_flash_update(struct dsa_switch *ds,
 	if (!ret) {
 		/* lift the block to query the new firmware version */
 		priv->block_host = false;
+		priv->rescue_mode = false;
 		memset(&ver, 0, sizeof(ver));
 		if (!MXL862XX_API_READ_QUIET(priv, SYS_MISC_FW_VERSION, ver) &&
 		    ver.iv_major)

@@ -5,6 +5,9 @@
 
 #include <net/dsa.h>
 
+struct mxl862xx_priv;
+
+bool mxl862xx_rescue_mode_detect(struct mxl862xx_priv *priv);
 int mxl862xx_devlink_info_get(struct dsa_switch *ds,
 			      struct devlink_info_req *req,
 			      struct netlink_ext_ack *extack);

@@ -340,6 +340,9 @@ int mxl862xx_api_wrap(struct mxl862xx_priv *priv, u16 cmd, void *_data,
 	if (priv->skip_teardown)
 		return 0;
 
+	if (priv->rescue_mode)
+		return -ENODEV;
+
 	if (priv->block_host && cmd != SYS_MISC_FW_UPDATE)
 		return -EBUSY;
 

@@ -406,6 +406,8 @@ mxl862xx_phylink_mac_select_pcs(struct phylink_config *config,
 
 	switch (port) {
 	case 9 ... 16:
+		if (priv->rescue_mode)
+			return NULL;
 		if (!MXL862XX_FW_VER_MIN(priv, 1, 0, 84)) {
 			dev_warn_once(dp->ds->dev,
 				      "SerDes PCS unsupported on old firmware.\n");

@@ -629,9 +629,22 @@ static int mxl862xx_setup(struct dsa_switch *ds)
 	if (ret)
 		return ret;
 
-	ret = mxl862xx_wait_ready(ds);
-	if (ret)
-		return ret;
+	priv->rescue_mode = mxl862xx_rescue_mode_detect(priv);
+	if (!priv->rescue_mode) {
+		ret = mxl862xx_wait_ready(ds);
+		if (ret) {
+			/* the reset may only now have triggered rescue mode */
+			priv->rescue_mode = mxl862xx_rescue_mode_detect(priv);
+			if (!priv->rescue_mode)
+				return ret;
+		}
+	}
+
+	if (priv->rescue_mode) {
+		dev_warn(ds->dev,
+			 "switch stuck in MCUboot rescue mode, use devlink to flash new firmware\n");
+		return 0;
+	}
 
 	mutex_init(&priv->serdes_lock);
 	for (i = 0; i < ARRAY_SIZE(priv->serdes_ports); i++)

@@ -716,11 +729,21 @@ static int mxl862xx_port_state(struct dsa_switch *ds, int port, bool enable)
 static int mxl862xx_port_enable(struct dsa_switch *ds, int port,
 				struct phy_device *phydev)
 {
+	struct mxl862xx_priv *priv = ds->priv;
+
+	if (priv->rescue_mode)
+		return 0;
+
 	return mxl862xx_port_state(ds, port, true);
 }
 
 static void mxl862xx_port_disable(struct dsa_switch *ds, int port)
 {
+	struct mxl862xx_priv *priv = ds->priv;
+
+	if (priv->rescue_mode)
+		return;
+
 	if (mxl862xx_port_state(ds, port, false))
 		dev_err(ds->dev, "failed to disable port %d\n", port);
 }

@@ -1338,6 +1361,12 @@ static int mxl862xx_port_setup(struct dsa_switch *ds, int port)
 	bool is_cpu_port = dsa_port_is_cpu(dp);
 	int ret;
 
+	/* DSA reinits failed user ports as unused; shared ports must
+	 * succeed for the tree to register.
+	 */
+	if (priv->rescue_mode)
+		return dsa_port_is_user(dp) ? -ENODEV : 0;
+
 	ret = mxl862xx_port_state(ds, port, false);
 	if (ret)
 		return ret;

@@ -1629,6 +1658,9 @@ static void mxl862xx_port_stp_state_set(struct dsa_switch *ds, int port,
 	struct mxl862xx_priv *priv = ds->priv;
 	int ret;
 
+	if (priv->rescue_mode)
+		return;
+
 	switch (state) {
 	case BR_STATE_DISABLED:
 		param.port_state = cpu_to_le32(MXL862XX_STP_PORT_STATE_DISABLE);

@@ -323,6 +323,8 @@ struct mxl862xx_fw_version {
  *                      during a firmware flash
  * @skip_teardown:      discard firmware API commands during the teardown
  *                      triggered by the post-flash reprobe
+ * @rescue_mode:        switch is stuck in MCUboot; firmware API commands
+ *                      fail fast, only clause-22 SMDIO works
  * @stats_work:         periodic work item that polls RMON hardware counters
  *                      and accumulates them into 64-bit per-port stats
  */

@@ -343,6 +345,7 @@ struct mxl862xx_priv {
 	u16 vf_block_size;
 	bool block_host;
 	bool skip_teardown;
+	bool rescue_mode;
 	struct delayed_work stats_work;
 };