USB4: For AP mode entry, add support for active cables

For AP mode entry, request to enter Thunderbolt cable mode
entry prior to entering USB4 mode if -
1. Thunderbolt Mode SOP' VDO active/passive bit (B25) is
   TBT_CABLE_ACTIVE or
2. It's an active cable with VDM version < 2.0 or
   VDO version < 1.3

BUG=b:181286325
BRANCH=None
TEST=Able to enter USB4 mode with LRD cable

Signed-off-by: Ayushee Shah <ayushee.shah@intel.com>
Change-Id: Ie223fa3d95c2357a0e50aeea93444e6f7639cc3f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2724653
Reviewed-by: Abe Levkoy <alevkoy@chromium.org>

3 files changed, 47 insertions, 18 deletions

diff --git a/common/usbc/tbt_alt_mode.c b/common/usbc/tbt_alt_mode.c
index 793de4c778..3ce66f7e5d 100644
--- a/common/usbc/tbt_alt_mode.c
+++ b/common/usbc/tbt_alt_mode.c
@@ -222,6 +222,37 @@ static void tbt_active_cable_exit_mode(int port)
 		tbt_state[port] = TBT_EXIT_SOP_PRIME;
 }
 
+bool tbt_cable_entry_required_for_usb4(int port)
+{
+	struct pd_discovery *disc_sop_prime;
+	union tbt_mode_resp_cable cable_mode_resp;
+
+	/* Request to enter Thunderbolt mode for the cable prior to entering
+	 * USB4 mode if -
+	 * 1. Thunderbolt Mode SOP' VDO active/passive bit (B25) is
+	 *    TBT_CABLE_ACTIVE or
+	 * 2. It's an active cable with VDM version < 2.0 or
+	 *    VDO version < 1.3
+	 */
+	if (tbt_cable_entry_is_done(port))
+		return false;
+
+	cable_mode_resp.raw_value =
+			pd_get_tbt_mode_vdo(port, TCPC_TX_SOP_PRIME);
+
+	if (cable_mode_resp.tbt_active_passive == TBT_CABLE_ACTIVE)
+		return true;
+
+	if (get_usb_pd_cable_type(port) == IDH_PTYPE_ACABLE) {
+		disc_sop_prime = pd_get_am_discovery(port, TCPC_TX_SOP_PRIME);
+		if (pd_get_vdo_ver(port, TCPC_TX_SOP_PRIME) < VDM_VER20 ||
+		    disc_sop_prime->identity.product_t1.a_rev30.vdo_ver <
+							VDO_VERSION_1_3)
+			return true;
+	}
+	return false;
+}
+
 void intel_vdm_acked(int port, enum tcpm_transmit_type type, int vdo_count,
 		uint32_t *vdm)
 {
diff --git a/common/usbc/usb_pd_dpm.c b/common/usbc/usb_pd_dpm.c
index 716c63d175..7e7c002721 100644
--- a/common/usbc/usb_pd_dpm.c
+++ b/common/usbc/usb_pd_dpm.c
@@ -280,26 +280,14 @@ static void dpm_attempt_mode_entry(int port)
 	    enter_usb_port_partner_is_capable(port) &&
 	    enter_usb_cable_is_capable(port) &&
 	    dpm_mode_entry_requested(port, TYPEC_MODE_USB4)) {
-		struct pd_discovery *disc_sop_prime =
-			pd_get_am_discovery(port, TCPC_TX_SOP_PRIME);
-		union tbt_mode_resp_cable cable_mode_resp = {
-			.raw_value = pd_get_tbt_mode_vdo(port,
-						TCPC_TX_SOP_PRIME) };
 		/*
-		 * Enter USB mode if -
-		 * 1. It's a passive cable and Thunderbolt Mode SOP' VDO
-		 *    active/passive bit (B25) is TBT_CABLE_PASSIVE or
-		 * 2. It's a active cable with VDM version >= 2.0 and
-		 *    VDO version >= 1.3 or
-		 * 3. The cable has entered Thunderbolt mode.
+		 * For certain cables, enter Thunderbolt alt mode with the
+		 * cable and USB4 mode with the port partner.
 		 */
-		if ((get_usb_pd_cable_type(port) == IDH_PTYPE_PCABLE &&
-		     cable_mode_resp.tbt_active_passive == TBT_CABLE_PASSIVE) ||
-		    (get_usb_pd_cable_type(port) == IDH_PTYPE_ACABLE &&
-		     pd_get_vdo_ver(port, TCPC_TX_SOP_PRIME) >= VDM_VER20 &&
-		     disc_sop_prime->identity.product_t1.a_rev30.vdo_ver >=
-							VDO_VERSION_1_3) ||
-		     tbt_cable_entry_is_done(port)) {
+		if (tbt_cable_entry_required_for_usb4(port)) {
+			vdo_count = tbt_setup_next_vdm(port,
+				ARRAY_SIZE(vdm), vdm, &tx_type);
+		} else {
 			pd_dpm_request(port, DPM_REQUEST_ENTER_USB);
 			return;
 		}
diff --git a/include/usb_tbt_alt_mode.h b/include/usb_tbt_alt_mode.h
index 3be7c60205..01604d72ae 100644
--- a/include/usb_tbt_alt_mode.h
+++ b/include/usb_tbt_alt_mode.h
@@ -30,6 +30,16 @@ void tbt_init(int port);
 void tbt_exit_mode_request(int port);
 
 /*
+ * Checks whether Thunderbolt cable mode entry is required prior to entering
+ * USB4.
+ *
+ * @param port      USB-C port number
+ * @return          True if Thunderbolt cable mode entry is required
+ *		    False otherwise
+ */
+bool tbt_cable_entry_required_for_usb4(int port);
+
+/*
  * Checks whether the mode entry sequence for Thunderbolt alternate mode is
  * done for a port.
  *