usb/typec: tcpm: Add generic extcon to tcpm

This patch adds automatic extcon creation to the tcpm driver. This patch
is incomplete and needs some work regarding support of all the available
extcon states and their management.
To make proper use of this extension this patch adds loading of supported
port altmodes from devicetrees, too.

drivers/usb/typec/tcpm/tcpm.c

@@ -1216,6 +1216,7 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
 			modep->svid_index++;
 			if (modep->svid_index < modep->nsvids) {
 				u16 svid = modep->svids[modep->svid_index];
+				tcpm_log(port, "More modes available, sending discover");
 				response[0] = VDO(svid, 1, CMD_DISCOVER_MODES);
 				rlen = 1;
 			} else {
@@ -4548,6 +4549,60 @@ unsigned int default_supported_cables[] = {
 	EXTCON_NONE
 };
 
+static int tcpm_fw_get_caps_late(struct tcpm_port *port,
+			    struct fwnode_handle *fwnode)
+{
+	int ret, i;
+	ret = fwnode_property_count_u32(fwnode, "typec-altmodes");
+	if (ret > 0) {
+		u32 *props;
+		if (ret % 4) {
+			dev_err(port->dev, "Length of typec altmode array must be divisible by 4");
+			return -EINVAL;
+		}
+
+		props = devm_kzalloc(port->dev, sizeof(u32) * ret, GFP_KERNEL);
+		if (!props) {
+			dev_err(port->dev, "Failed to allocate memory for altmode properties");
+			return -ENOMEM;
+		}
+
+		if(fwnode_property_read_u32_array(fwnode, "typec-altmodes", props, ret) < 0) {
+			dev_err(port->dev, "Failed to read altmodes from port");
+			return -EINVAL;
+		}
+
+		i = 0;
+		while (ret > 0 && i < ARRAY_SIZE(port->port_altmode)) {
+			struct typec_altmode *alt;
+			struct typec_altmode_desc alt_desc = {
+				.svid = props[i * 4],
+				.mode = props[i * 4 + 1],
+				.vdo  = props[i * 4 + 2],
+				.roles = props[i * 4 + 3],
+			};
+
+
+			tcpm_log(port, "Adding altmode SVID: 0x%04x, mode: %d, vdo: %u, role: %d",
+				alt_desc.svid, alt_desc.mode, alt_desc.vdo, alt_desc.roles);
+			alt = typec_port_register_altmode(port->typec_port,
+							  &alt_desc);
+			if (IS_ERR(alt)) {
+				tcpm_log(port,
+					 "%s: failed to register port alternate mode 0x%x",
+					 dev_name(port->dev), alt_desc.svid);
+				break;
+			}
+			typec_altmode_set_drvdata(alt, port);
+			alt->ops = &tcpm_altmode_ops;
+			port->port_altmode[i] = alt;
+			i++;
+			ret -= 4;
+		}
+	}
+	return 0;
+}
+
 static int tcpm_fw_get_caps(struct tcpm_port *port,
 			    struct fwnode_handle *fwnode)
 {
@@ -4945,6 +5000,12 @@ struct tcpm_port *tcpm_register_port(struct device *dev, struct tcpc_dev *tcpc)
 		goto out_role_sw_put;
 	}
 
+	err = tcpm_fw_get_caps_late(port, tcpc->fwnode);
+	if (err < 0) {
+		dev_err(dev, "Failed to get altmodes from fwnode");
+		goto out_destroy_wq;
+	}
+
 	mutex_lock(&port->lock);
 	tcpm_init(port);
 	mutex_unlock(&port->lock);