platform/chrome: cros_typec_vdm: Add VDM reply support

Handle response VDMs which are sent by the partner (replying to VDMs
sent by the host system itself). These get forwarded to the altmode
driver.

Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Prashant Malani <pmalani@chromium.org>
Reviewed-by: Benson Leung <bleung@chromium.org>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20221228004648.793339-10-pmalani@chromium.org

drivers/platform/chrome/cros_ec_typec.c

@@ -1000,6 +1000,13 @@ static void cros_typec_handle_status(struct cros_typec_data *typec, int port_num
 					 "Failed SOP Disc event clear, port: %d\n", port_num);
 		}
 	}
+
+	if (resp.events & PD_STATUS_EVENT_VDM_REQ_REPLY) {
+		cros_typec_handle_vdm_response(typec, port_num);
+		ret = cros_typec_send_clear_event(typec, port_num, PD_STATUS_EVENT_VDM_REQ_REPLY);
+		if (ret < 0)
+			dev_warn(typec->dev, "Failed VDM Reply event clear, port: %d\n", port_num);
+	}
 }
 
 static int cros_typec_port_update(struct cros_typec_data *typec, int port_num)

drivers/platform/chrome/cros_typec_vdm.c

@@ -13,6 +13,45 @@
 #include "cros_ec_typec.h"
 #include "cros_typec_vdm.h"
 
+/*
+ * Retrieves a VDM response from the EC and forwards it to the altmode driver based on SVID.
+ */
+void cros_typec_handle_vdm_response(struct cros_typec_data *typec, int port_num)
+{
+	struct ec_response_typec_vdm_response resp;
+	struct ec_params_typec_vdm_response req = {
+		.port = port_num,
+	};
+	struct typec_altmode *amode;
+	u16 svid;
+	u32 hdr;
+	int ret;
+
+	ret = cros_ec_cmd(typec->ec, 0, EC_CMD_TYPEC_VDM_RESPONSE, &req,
+			  sizeof(req), &resp, sizeof(resp));
+	if (ret < 0) {
+		dev_warn(typec->dev, "Failed VDM response fetch, port: %d\n", port_num);
+		return;
+	}
+
+	hdr = resp.vdm_response[0];
+	svid = PD_VDO_VID(hdr);
+	dev_dbg(typec->dev, "Received VDM header: %x, port: %d\n", hdr, port_num);
+
+	amode = typec_match_altmode(typec->ports[port_num]->port_altmode, CROS_EC_ALTMODE_MAX,
+				    svid, PD_VDO_OPOS(hdr));
+	if (!amode) {
+		dev_err(typec->dev, "Received VDM for unregistered altmode (SVID:%x), port: %d\n",
+			svid, port_num);
+		return;
+	}
+
+	ret = typec_altmode_vdm(amode, hdr, &resp.vdm_response[1], resp.vdm_data_objects);
+	if (ret)
+		dev_err(typec->dev, "Failed to forward VDM to altmode (SVID:%x), port: %d\n",
+			svid, port_num);
+}
+
 static int cros_typec_port_amode_enter(struct typec_altmode *amode, u32 *vdo)
 {
 	struct cros_typec_port *port = typec_altmode_get_drvdata(amode);

drivers/platform/chrome/cros_typec_vdm.h

@@ -7,4 +7,6 @@
 
 extern struct typec_altmode_ops port_amode_ops;
 
+void cros_typec_handle_vdm_response(struct cros_typec_data *typec, int port_num);
+
 #endif /*  __CROS_TYPEC_VDM__ */