usb: typec: tcpci: add attempt_vconn_swap_discovery callback

Add attempt_vconn_swap_discovery callback to determine whether the TCPM
should perform a Vconn swap following Discover Identity on SOP. The tcpci
will return false unless chip level drivers implement the callback.

Maxim based TCPCs will return true unless the last connection resulted in
a Vconn Over Current Fault, which may be the result of the Vconn swap. In
addition to the port resetting, the TCPCI will veto the next Vconn swap
from occurring.

Signed-off-by: RD Babiera <rdbabiera@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20240108191620.987785-21-rdbabiera@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/usb/tcpm.h b/include/linux/usb/tcpm.h
index 41d1ac9c8bbf..6671427f7eeb 100644
--- a/include/linux/usb/tcpm.h
+++ b/include/linux/usb/tcpm.h
@@ -122,6 +122,14 @@ enum tcpm_transmit_type {
  * @cable_comm_capable
  *		Optional; Returns whether cable communication over SOP' is supported
  *		by the tcpc
+ * @attempt_vconn_swap_discovery:
+ *		Optional; The callback is called by the TCPM when the result of
+ *		a Discover Identity request indicates that the port partner is
+ *		a receptacle capable of modal operation. Chip level TCPCI drivers
+ *		can implement their own policy to determine if and when a Vconn
+ *		swap following Discover Identity on SOP' occurs.
+ *		Return true when the TCPM is allowed to request a Vconn swap
+ *		after Discovery Identity on SOP.
  */
 struct tcpc_dev {
 	struct fwnode_handle *fwnode;
@@ -158,6 +166,7 @@ struct tcpc_dev {
 	void (*set_partner_usb_comm_capable)(struct tcpc_dev *dev, bool enable);
 	void (*check_contaminant)(struct tcpc_dev *dev);
 	bool (*cable_comm_capable)(struct tcpc_dev *dev);
+	bool (*attempt_vconn_swap_discovery)(struct tcpc_dev *dev);
 };
 
 struct tcpm_port;