thunderbolt: Read router NVM version before applying quirks

The router NVM version is currently only available after the NVMem devices
have been registered. This is too late for firmware-dependent quirks that
are evaluated during tb_switch_add() before device registration.

Split router NVM handling into two phases:
  - tb_switch_nvm_init() allocates the NVM object and reads the version
  - tb_switch_nvm_add() registers the NVMem devices using the pre-read NVM

This makes the NVM major/minor version available before tb_check_quirks()
without changing when the NVMem devices are registered.

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

Author: Rene Sapiens

drivers/thunderbolt/switch.c

@@ -347,7 +347,7 @@ static int nvm_write(void *priv, unsigned int offset, void *val, size_t bytes)
 	return ret;
 }
 
-static int tb_switch_nvm_add(struct tb_switch *sw)
+static int tb_switch_nvm_init(struct tb_switch *sw)
 {
 	struct tb_nvm *nvm;
 	int ret;
@@ -365,6 +365,26 @@ static int tb_switch_nvm_add(struct tb_switch *sw)
 	if (ret)
 		goto err_nvm;
 
+	sw->nvm = nvm;
+	return 0;
+
+err_nvm:
+	tb_sw_dbg(sw, "NVM upgrade disabled\n");
+	sw->no_nvm_upgrade = true;
+	if (!IS_ERR(nvm))
+		tb_nvm_free(nvm);
+
+	return ret;
+}
+
+static int tb_switch_nvm_add(struct tb_switch *sw)
+{
+	struct tb_nvm *nvm = sw->nvm;
+	int ret;
+
+	if (!nvm)
+		return 0;
+
 	/*
 	 * If the switch is in safe-mode the only accessible portion of
 	 * the NVM is the non-active one where userspace is expected to
@@ -383,14 +403,12 @@ static int tb_switch_nvm_add(struct tb_switch *sw)
 			goto err_nvm;
 	}
 
-	sw->nvm = nvm;
 	return 0;
 
 err_nvm:
 	tb_sw_dbg(sw, "NVM upgrade disabled\n");
 	sw->no_nvm_upgrade = true;
-	if (!IS_ERR(nvm))
-		tb_nvm_free(nvm);
+	tb_nvm_free(nvm);
 
 	return ret;
 }
@@ -3311,6 +3329,10 @@ int tb_switch_add(struct tb_switch *sw)
 		return ret;
 	}
 
+	ret = tb_switch_nvm_init(sw);
+	if (ret)
+		return ret;
+
 	if (!sw->safe_mode) {
 		tb_switch_credits_init(sw);