usb: typec: tcpm: allow sink (ufp) to toggle into accessory mode debug

JIRA: https://issues.redhat.com/browse/RHEL-116016

commit 8db73e6
Author: Michael Grzeschik <m.grzeschik@pengutronix.de>
Date: Fri, 4 Apr 2025 00:43:05 +0200

  This patch extends the is_debug macro to cover the sink case (ufp). It
  also handles the transition to access the DEBUG_ACC_ATTACHED state in
  the sink case. It also handles the debounce case in which the cc
  pins are not immediately valid after the plug event.

  Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
  Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
  Link: https://lore.kernel.org/r/20250404-ml-topic-tcpm-v1-2-b99f44badce8@pengutronix.de
  Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Desnes Nunes <desnesn@redhat.com>

Author: Desnes Nunes

drivers/usb/typec/tcpm/tcpm.c

@@ -67,6 +67,7 @@
 						\
 	S(ACC_UNATTACHED),			\
 	S(DEBUG_ACC_ATTACHED),			\
+	S(DEBUG_ACC_DEBOUNCE),			\
 	S(AUDIO_ACC_ATTACHED),			\
 	S(AUDIO_ACC_DEBOUNCE),			\
 						\
@@ -621,7 +622,8 @@ static const char * const pd_rev[] = {
 	  !tcpm_cc_is_source((port)->cc1)))
 
 #define tcpm_port_is_debug(port) \
-	(tcpm_cc_is_source((port)->cc1) && tcpm_cc_is_source((port)->cc2))
+	((tcpm_cc_is_source((port)->cc1) && tcpm_cc_is_source((port)->cc2)) || \
+	 (tcpm_cc_is_sink((port)->cc1) && tcpm_cc_is_sink((port)->cc2)))
 
 #define tcpm_port_is_audio(port) \
 	(tcpm_cc_is_audio((port)->cc1) && tcpm_cc_is_audio((port)->cc2))
@@ -4969,7 +4971,13 @@ static void run_state_machine(struct tcpm_port *port)
 			tcpm_set_state(port, SRC_UNATTACHED, PD_T_DRP_SRC);
 		break;
 	case SNK_ATTACH_WAIT:
-		if ((port->cc1 == TYPEC_CC_OPEN &&
+		if (tcpm_port_is_debug(port))
+			tcpm_set_state(port, DEBUG_ACC_ATTACHED,
+				       PD_T_CC_DEBOUNCE);
+		else if (tcpm_port_is_audio(port))
+			tcpm_set_state(port, AUDIO_ACC_ATTACHED,
+				       PD_T_CC_DEBOUNCE);
+		else if ((port->cc1 == TYPEC_CC_OPEN &&
 		     port->cc2 != TYPEC_CC_OPEN) ||
 		    (port->cc1 != TYPEC_CC_OPEN &&
 		     port->cc2 == TYPEC_CC_OPEN))
@@ -4983,6 +4991,12 @@ static void run_state_machine(struct tcpm_port *port)
 		if (tcpm_port_is_disconnected(port))
 			tcpm_set_state(port, SNK_UNATTACHED,
 				       PD_T_PD_DEBOUNCE);
+		else if (tcpm_port_is_debug(port))
+			tcpm_set_state(port, DEBUG_ACC_ATTACHED,
+				       PD_T_CC_DEBOUNCE);
+		else if (tcpm_port_is_audio(port))
+			tcpm_set_state(port, AUDIO_ACC_ATTACHED,
+				       PD_T_CC_DEBOUNCE);
 		else if (port->vbus_present)
 			tcpm_set_state(port,
 				       tcpm_try_src(port) ? SRC_TRY
@@ -5281,14 +5295,18 @@ static void run_state_machine(struct tcpm_port *port)
 	/* Accessory states */
 	case ACC_UNATTACHED:
 		tcpm_acc_detach(port);
-		tcpm_set_state(port, SRC_UNATTACHED, 0);
+		if (port->port_type == TYPEC_PORT_SRC)
+			tcpm_set_state(port, SRC_UNATTACHED, 0);
+		else
+			tcpm_set_state(port, SNK_UNATTACHED, 0);
 		break;
 	case DEBUG_ACC_ATTACHED:
 	case AUDIO_ACC_ATTACHED:
 		ret = tcpm_acc_attach(port);
 		if (ret < 0)
 			tcpm_set_state(port, ACC_UNATTACHED, 0);
 		break;
+	case DEBUG_ACC_DEBOUNCE:
 	case AUDIO_ACC_DEBOUNCE:
 		tcpm_set_state(port, ACC_UNATTACHED, port->timings.cc_debounce_time);
 		break;
@@ -5880,7 +5898,8 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
 		}
 		break;
 	case SNK_UNATTACHED:
-		if (tcpm_port_is_sink(port))
+		if (tcpm_port_is_debug(port) || tcpm_port_is_audio(port) ||
+		    tcpm_port_is_sink(port))
 			tcpm_set_state(port, SNK_ATTACH_WAIT, 0);
 		break;
 	case SNK_ATTACH_WAIT:
@@ -5943,7 +5962,12 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
 
 	case DEBUG_ACC_ATTACHED:
 		if (cc1 == TYPEC_CC_OPEN || cc2 == TYPEC_CC_OPEN)
-			tcpm_set_state(port, ACC_UNATTACHED, 0);
+			tcpm_set_state(port, DEBUG_ACC_DEBOUNCE, 0);
+		break;
+
+	case DEBUG_ACC_DEBOUNCE:
+		if (tcpm_port_is_debug(port))
+			tcpm_set_state(port, DEBUG_ACC_ATTACHED, 0);
 		break;
 
 	case SNK_TRY: