usb: typec: altmodes: add svdm version info for typec cables

Add typec_cable_set_svdm_version and typec_get_cable_svdm version symbols.
Cables can operate under a lower PD revision than the port partner, and the
max SVDM version is tied to the PD revision. So, typec_cable maintains its
own svdm_version.

Add typec_altmode_get_cable_svdm_version to return the cable's negotiated
svdm_version for altmode drivers to use.
Signed-off-by: RD Babiera <rdbabiera@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20240108191620.987785-16-rdbabiera@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/class.c

@@ -2131,6 +2131,46 @@ int typec_get_negotiated_svdm_version(struct typec_port *port)
 }
 EXPORT_SYMBOL_GPL(typec_get_negotiated_svdm_version);
 
+/**
+ * typec_get_cable_svdm_version - Get cable negotiated SVDM Version
+ * @port: USB Type-C Port.
+ *
+ * Get the negotiated SVDM Version for the cable. The Version is set to the port
+ * default value based on the PD Revision during cable registration, and updated
+ * after a successful Discover Identity if the negotiated value is less than the
+ * default.
+ *
+ * Returns usb_pd_svdm_ver if the cable has been registered otherwise -ENODEV.
+ */
+int typec_get_cable_svdm_version(struct typec_port *port)
+{
+	enum usb_pd_svdm_ver svdm_version;
+	struct device *cable_dev;
+
+	cable_dev = device_find_child(&port->dev, NULL, cable_match);
+	if (!cable_dev)
+		return -ENODEV;
+
+	svdm_version = to_typec_cable(cable_dev)->svdm_version;
+	put_device(cable_dev);
+
+	return svdm_version;
+}
+EXPORT_SYMBOL_GPL(typec_get_cable_svdm_version);
+
+/**
+ * typec_cable_set_svdm_version - Set negotiated Structured VDM (SVDM) Version
+ * @cable: USB Type-C Active Cable that supports SVDM
+ * @svdm_version: Negotiated SVDM Version
+ *
+ * This routine is used to save the negotiated SVDM Version.
+ */
+void typec_cable_set_svdm_version(struct typec_cable *cable, enum usb_pd_svdm_ver svdm_version)
+{
+	cable->svdm_version = svdm_version;
+}
+EXPORT_SYMBOL_GPL(typec_cable_set_svdm_version);
+
 /**
  * typec_get_drvdata - Return private driver data pointer
  * @port: USB Type-C port

drivers/usb/typec/class.h

@@ -23,6 +23,7 @@ struct typec_cable {
 	struct usb_pd_identity		*identity;
 	unsigned int			active:1;
 	u16				pd_revision; /* 0300H = "3.0" */
+	enum usb_pd_svdm_ver		svdm_version;
 };
 
 struct typec_partner {

include/linux/usb/typec.h

@@ -337,6 +337,9 @@ void typec_partner_set_svdm_version(struct typec_partner *partner,
 				    enum usb_pd_svdm_ver svdm_version);
 int typec_get_negotiated_svdm_version(struct typec_port *port);
 
+int typec_get_cable_svdm_version(struct typec_port *port);
+void typec_cable_set_svdm_version(struct typec_cable *cable, enum usb_pd_svdm_ver svdm_version);
+
 struct usb_power_delivery *typec_partner_usb_power_delivery_register(struct typec_partner *partner,
 							struct usb_power_delivery_desc *desc);
 

include/linux/usb/typec_altmode.h

@@ -95,6 +95,16 @@ int typec_cable_altmode_exit(struct typec_altmode *altmode, enum typec_plug_inde
 int typec_cable_altmode_vdm(struct typec_altmode *altmode, enum typec_plug_index sop,
 			    const u32 header, const u32 *vdo, int count);
 
+/**
+ * typec_altmode_get_cable_svdm_version - Get negotiated SVDM version for cable plug
+ * @altmode: Handle to the alternate mode
+ */
+static inline int
+typec_altmode_get_cable_svdm_version(struct typec_altmode *altmode)
+{
+	return typec_get_cable_svdm_version(typec_altmode2port(altmode));
+}
+
 /*
  * These are the connector states (USB, Safe and Alt Mode) defined in USB Type-C
  * Specification. SVID specific connector states are expected to follow and