usb: typec: Add attribute file showing the supported USB modes of the port

This attribute file, named "usb_capability", will show the
supported USB modes, which are USB 2.0, USB 3.2 and USB4.
These modes are defined in the USB Type-C (R2.0) and USB
Power Delivery (R3.0 V2.0) Specifications.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20241016131834.898599-2-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 82 insertions, 0 deletions

diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
index 9262fcd4144f..2f12269d1465 100644
--- a/drivers/usb/typec/class.c
+++ b/drivers/usb/typec/class.c
@@ -219,6 +219,13 @@ static ssize_t usb_power_delivery_revision_show(struct device *dev,
 						char *buf);
 static DEVICE_ATTR_RO(usb_power_delivery_revision);
 
+static const char * const usb_modes[] = {
+	[USB_MODE_NONE] = "none",
+	[USB_MODE_USB2] = "usb2",
+	[USB_MODE_USB3] = "usb3",
+	[USB_MODE_USB4] = "usb4"
+};
+
 /* ------------------------------------------------------------------------- */
 /* Alternate Modes */
 
@@ -1290,6 +1297,67 @@ EXPORT_SYMBOL_GPL(typec_unregister_cable);
 /* USB Type-C ports */
 
 /**
+ * typec_port_set_usb_mode - Set the operational USB mode for the port
+ * @port: USB Type-C port
+ * @mode: USB Mode (USB2, USB3 or USB4)
+ *
+ * @mode will be used with the next Enter_USB message. Existing connections are
+ * not affected.
+ */
+void typec_port_set_usb_mode(struct typec_port *port, enum usb_mode mode)
+{
+	port->usb_mode = mode;
+}
+EXPORT_SYMBOL_GPL(typec_port_set_usb_mode);
+
+static ssize_t
+usb_capability_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct typec_port *port = to_typec_port(dev);
+	int len = 0;
+	int i;
+
+	for (i = USB_MODE_USB2; i < USB_MODE_USB4 + 1; i++) {
+		if (!(BIT(i - 1) & port->cap->usb_capability))
+			continue;
+
+		if (i == port->usb_mode)
+			len += sysfs_emit_at(buf, len, "[%s] ", usb_modes[i]);
+		else
+			len += sysfs_emit_at(buf, len, "%s ", usb_modes[i]);
+	}
+
+	sysfs_emit_at(buf, len - 1, "\n");
+
+	return len;
+}
+
+static ssize_t
+usb_capability_store(struct device *dev, struct device_attribute *attr,
+		     const char *buf, size_t size)
+{
+	struct typec_port *port = to_typec_port(dev);
+	int ret = 0;
+	int mode;
+
+	if (!port->ops || !port->ops->default_usb_mode_set)
+		return -EOPNOTSUPP;
+
+	mode = sysfs_match_string(usb_modes, buf);
+	if (mode < 0)
+		return mode;
+
+	ret = port->ops->default_usb_mode_set(port, mode);
+	if (ret)
+		return ret;
+
+	port->usb_mode = mode;
+
+	return size;
+}
+static DEVICE_ATTR_RW(usb_capability);
+
+/**
  * typec_port_set_usb_power_delivery - Assign USB PD for port.
  * @port: USB Type-C port.
  * @pd: USB PD instance.
@@ -1757,6 +1825,7 @@ static struct attribute *typec_attrs[] = {
 	&dev_attr_vconn_source.attr,
 	&dev_attr_port_type.attr,
 	&dev_attr_orientation.attr,
+	&dev_attr_usb_capability.attr,
 	NULL,
 };
 
@@ -1790,6 +1859,11 @@ static umode_t typec_attr_is_visible(struct kobject *kobj,
 		if (port->cap->orientation_aware)
 			return 0444;
 		return 0;
+	} else if (attr == &dev_attr_usb_capability.attr) {
+		if (!port->cap->usb_capability)
+			return 0;
+		if (!port->ops || !port->ops->default_usb_mode_set)
+			return 0444;
 	}
 
 	return attr->mode;
@@ -2428,6 +2502,13 @@ struct typec_port *typec_register_port(struct device *parent,
 	port->con.attach = typec_partner_attach;
 	port->con.deattach = typec_partner_deattach;
 
+	if (cap->usb_capability & USB_CAPABILITY_USB4)
+		port->usb_mode = USB_MODE_USB4;
+	else if (cap->usb_capability & USB_CAPABILITY_USB3)
+		port->usb_mode = USB_MODE_USB3;
+	else if (cap->usb_capability & USB_CAPABILITY_USB2)
+		port->usb_mode = USB_MODE_USB2;
+
 	device_initialize(&port->dev);
 	port->dev.class = &typec_class;
 	port->dev.parent = parent;
diff --git a/drivers/usb/typec/class.h b/drivers/usb/typec/class.h
index 7485cdb9dd20..85bc50aa54f7 100644
--- a/drivers/usb/typec/class.h
+++ b/drivers/usb/typec/class.h
@@ -55,6 +55,7 @@ struct typec_port {
 	enum typec_role			vconn_role;
 	enum typec_pwr_opmode		pwr_opmode;
 	enum typec_port_type		port_type;
+	enum usb_mode			usb_mode;
 	struct mutex			port_type_lock;
 
 	enum typec_orientation		orientation;