usb: typec: tcpm: Add callbacks to mitigate wakeups due to contaminant

On some of the TCPC implementations, when the Type-C port is exposed
to contaminants, such as water, TCPC stops toggling while reporting OPEN
either by the time TCPM reads CC pin status or during CC debounce
window. This causes TCPM to be stuck in TOGGLING state. If TCPM is made
to restart toggling, the behavior recurs causing redundant CPU wakeups
till the USB-C port is free of contaminant.

[206199.287817] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
[206199.640337] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
[206199.985789] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]

(or)

[ 7853.867577] Start toggling
[ 7853.889921] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
[ 7855.698765] CC1: 0 -> 0, CC2: 0 -> 5 [state TOGGLING, polarity 0, connected]
[ 7855.698790] state change TOGGLING -> SNK_ATTACH_WAIT [rev3 NONE_AMS]
[ 7855.698826] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @ 170 ms [rev3 NONE_AMS]
[ 7855.703559] CC1: 0 -> 0, CC2: 5 -> 5 [state SNK_ATTACH_WAIT, polarity 0, connected]
[ 7855.856555] CC1: 0 -> 0, CC2: 5 -> 0 [state SNK_ATTACH_WAIT, polarity 0, disconnected]
[ 7855.856581] state change SNK_ATTACH_WAIT -> SNK_ATTACH_WAIT [rev3 NONE_AMS]
[ 7855.856613] pending state change SNK_ATTACH_WAIT -> SNK_UNATTACHED @ 170 ms [rev3 NONE_AMS]
[ 7856.027744] state change SNK_ATTACH_WAIT -> SNK_UNATTACHED [delayed 170 ms]
[ 7856.181949] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
[ 7856.187896] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
[ 7857.645630] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
[ 7857.647291] CC1: 0 -> 0, CC2: 0 -> 5 [state TOGGLING, polarity 0, connected]
[ 7857.647298] state change TOGGLING -> SNK_ATTACH_WAIT [rev3 NONE_AMS]
[ 7857.647310] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @ 170 ms [rev3 NONE_AMS]
[ 7857.808106] CC1: 0 -> 0, CC2: 5 -> 0 [state SNK_ATTACH_WAIT, polarity 0, disconnected]
[ 7857.808123] state change SNK_ATTACH_WAIT -> SNK_ATTACH_WAIT [rev3 NONE_AMS]
[ 7857.808150] pending state change SNK_ATTACH_WAIT -> SNK_UNATTACHED @ 170 ms [rev3 NONE_AMS]
[ 7857.978727] state change SNK_ATTACH_WAIT -> SNK_UNATTACHED [delayed 170 ms]

To mitigate redundant TCPM wakeups, TCPCs which do have the needed hardware
can implement the check_contaminant callback which is invoked by TCPM
to evaluate for presence of contaminant. Lower level TCPC driver can
restart toggling through TCPM_PORT_CLEAN event when the driver detects
that USB-C port is free of contaminant. check_contaminant callback also
passes the disconnect_while_debounce flag which when true denotes that
the CC pins transitioned to OPEN state during the CC debounce window.

Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20230114093246.1933321-1-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 54 insertions, 1 deletions

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 904c7b4ce2f0..c624747f32df 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -36,6 +36,7 @@
 #define FOREACH_STATE(S)			\
 	S(INVALID_STATE),			\
 	S(TOGGLING),			\
+	S(CHECK_CONTAMINANT),			\
 	S(SRC_UNATTACHED),			\
 	S(SRC_ATTACH_WAIT),			\
 	S(SRC_ATTACHED),			\
@@ -249,6 +250,7 @@ enum frs_typec_current {
 #define TCPM_RESET_EVENT	BIT(2)
 #define TCPM_FRS_EVENT		BIT(3)
 #define TCPM_SOURCING_VBUS	BIT(4)
+#define TCPM_PORT_CLEAN		BIT(5)
 
 #define LOG_BUFFER_ENTRIES	1024
 #define LOG_BUFFER_ENTRY_SIZE	128
@@ -483,6 +485,13 @@ struct tcpm_port {
 	 * SNK_READY for non-pd link.
 	 */
 	bool slow_charger_loop;
+
+	/*
+	 * When true indicates that the lower level drivers indicate potential presence
+	 * of contaminant in the connector pins based on the tcpm state machine
+	 * transitions.
+	 */
+	bool potential_contaminant;
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *dentry;
 	struct mutex logbuffer_lock;	/* log buffer access lock */
@@ -647,7 +656,7 @@ static void tcpm_log(struct tcpm_port *port, const char *fmt, ...)
 	/* Do not log while disconnected and unattached */
 	if (tcpm_port_is_disconnected(port) &&
 	    (port->state == SRC_UNATTACHED || port->state == SNK_UNATTACHED ||
-	     port->state == TOGGLING))
+	     port->state == TOGGLING || port->state == CHECK_CONTAMINANT))
 		return;
 
 	va_start(args, fmt);
@@ -3904,15 +3913,28 @@ static void run_state_machine(struct tcpm_port *port)
 	unsigned int msecs;
 	enum tcpm_state upcoming_state;
 
+	if (port->tcpc->check_contaminant && port->state != CHECK_CONTAMINANT)
+		port->potential_contaminant = ((port->enter_state == SRC_ATTACH_WAIT &&
+						port->state == SRC_UNATTACHED) ||
+					       (port->enter_state == SNK_ATTACH_WAIT &&
+						port->state == SNK_UNATTACHED));
+
 	port->enter_state = port->state;
 	switch (port->state) {
 	case TOGGLING:
 		break;
+	case CHECK_CONTAMINANT:
+		port->tcpc->check_contaminant(port->tcpc);
+		break;
 	/* SRC states */
 	case SRC_UNATTACHED:
 		if (!port->non_pd_role_swap)
 			tcpm_swap_complete(port, -ENOTCONN);
 		tcpm_src_detach(port);
+		if (port->potential_contaminant) {
+			tcpm_set_state(port, CHECK_CONTAMINANT, 0);
+			break;
+		}
 		if (tcpm_start_toggling(port, tcpm_rp_cc(port))) {
 			tcpm_set_state(port, TOGGLING, 0);
 			break;
@@ -4150,6 +4172,10 @@ static void run_state_machine(struct tcpm_port *port)
 			tcpm_swap_complete(port, -ENOTCONN);
 		tcpm_pps_complete(port, -ENOTCONN);
 		tcpm_snk_detach(port);
+		if (port->potential_contaminant) {
+			tcpm_set_state(port, CHECK_CONTAMINANT, 0);
+			break;
+		}
 		if (tcpm_start_toggling(port, TYPEC_CC_RD)) {
 			tcpm_set_state(port, TOGGLING, 0);
 			break;
@@ -4926,6 +4952,9 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
 		else if (tcpm_port_is_sink(port))
 			tcpm_set_state(port, SNK_ATTACH_WAIT, 0);
 		break;
+	case CHECK_CONTAMINANT:
+		/* Wait for Toggling to be resumed */
+		break;
 	case SRC_UNATTACHED:
 	case ACC_UNATTACHED:
 		if (tcpm_port_is_debug(port) || tcpm_port_is_audio(port) ||
@@ -5425,6 +5454,15 @@ static void tcpm_pd_event_handler(struct kthread_work *work)
 			port->vbus_source = true;
 			_tcpm_pd_vbus_on(port);
 		}
+		if (events & TCPM_PORT_CLEAN) {
+			tcpm_log(port, "port clean");
+			if (port->state == CHECK_CONTAMINANT) {
+				if (tcpm_start_toggling(port, tcpm_rp_cc(port)))
+					tcpm_set_state(port, TOGGLING, 0);
+				else
+					tcpm_set_state(port, tcpm_default_state(port), 0);
+			}
+		}
 
 		spin_lock(&port->pd_event_lock);
 	}
@@ -5477,6 +5515,21 @@ void tcpm_sourcing_vbus(struct tcpm_port *port)
 }
 EXPORT_SYMBOL_GPL(tcpm_sourcing_vbus);
 
+void tcpm_port_clean(struct tcpm_port *port)
+{
+	spin_lock(&port->pd_event_lock);
+	port->pd_events |= TCPM_PORT_CLEAN;
+	spin_unlock(&port->pd_event_lock);
+	kthread_queue_work(port->wq, &port->event_work);
+}
+EXPORT_SYMBOL_GPL(tcpm_port_clean);
+
+bool tcpm_port_is_toggling(struct tcpm_port *port)
+{
+	return port->port_type == TYPEC_PORT_DRP && port->state == TOGGLING;
+}
+EXPORT_SYMBOL_GPL(tcpm_port_is_toggling);
+
 static void tcpm_enable_frs_work(struct kthread_work *work)
 {
 	struct tcpm_port *port = container_of(work, struct tcpm_port, enable_frs);