usb: typec: tcpm: Add Callback to Usb Communication capable partner

The USB Communications Capable bit indicates if port
partner is capable of communication over the USB data lines
(e.g. D+/- or SS Tx/Rx). Notify the status of the bit to low
level drivers to perform chip specific operation.
For instance, low level driver enables USB switches on D+/D-
lines to set up data path when the bit is set.

Refactored from patch initially authored by
Kyle Tso <kyletso@google.com>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Link: https://lore.kernel.org/r/20210202003101.221145-1-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpm.c

@@ -3430,6 +3430,14 @@ static void tcpm_unregister_altmodes(struct tcpm_port *port)
 	memset(modep, 0, sizeof(*modep));
 }
 
+static void tcpm_set_partner_usb_comm_capable(struct tcpm_port *port, bool capable)
+{
+	tcpm_log(port, "Setting usb_comm capable %s", capable ? "true" : "false");
+
+	if (port->tcpc->set_partner_usb_comm_capable)
+		port->tcpc->set_partner_usb_comm_capable(port->tcpc, capable);
+}
+
 static void tcpm_reset_port(struct tcpm_port *port)
 {
 	int ret;
@@ -3446,6 +3454,7 @@ static void tcpm_reset_port(struct tcpm_port *port)
 	port->attached = false;
 	port->pd_capable = false;
 	port->pps_data.supported = false;
+	tcpm_set_partner_usb_comm_capable(port, false);
 
 	/*
 	 * First Rx ID should be 0; set this to a sentinel of -1 so that
@@ -3786,6 +3795,8 @@ static void run_state_machine(struct tcpm_port *port)
 			}
 		} else {
 			tcpm_pd_send_control(port, PD_CTRL_ACCEPT);
+			tcpm_set_partner_usb_comm_capable(port,
+							  !!(port->sink_request & RDO_USB_COMM));
 			tcpm_set_state(port, SRC_TRANSITION_SUPPLY,
 				       PD_T_SRC_TRANSITION);
 		}
@@ -4005,6 +4016,8 @@ static void run_state_machine(struct tcpm_port *port)
 		break;
 	case SNK_NEGOTIATE_CAPABILITIES:
 		port->pd_capable = true;
+		tcpm_set_partner_usb_comm_capable(port,
+						  !!(port->source_caps[0] & PDO_FIXED_USB_COMM));
 		port->hard_reset_count = 0;
 		ret = tcpm_pd_send_request(port);
 		if (ret < 0) {

include/linux/usb/tcpm.h

@@ -108,6 +108,10 @@ enum tcpm_transmit_type {
  *		is supported by TCPC, set this callback for TCPM to query
  *		whether vbus is at VSAFE0V when needed.
  *		Returns true when vbus is at VSAFE0V, false otherwise.
+ * @set_partner_usb_comm_capable:
+ *              Optional; The USB Communications Capable bit indicates if port
+ *              partner is capable of communication over the USB data lines
+ *              (e.g. D+/- or SS Tx/Rx). Called to notify the status of the bit.
  */
 struct tcpc_dev {
 	struct fwnode_handle *fwnode;
@@ -139,6 +143,7 @@ struct tcpc_dev {
 	int (*set_auto_vbus_discharge_threshold)(struct tcpc_dev *dev, enum typec_pwr_opmode mode,
 						 bool pps_active, u32 requested_vbus_voltage);
 	bool (*is_vbus_vsafe0v)(struct tcpc_dev *dev);
+	void (*set_partner_usb_comm_capable)(struct tcpc_dev *dev, bool enable);
 };
 
 struct tcpm_port;