platform/chrome: cros_ec_typec: Thunderbolt support

Add support for entering and exiting Thunderbolt alt-mode using AP
driven alt-mode.

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Reviewed-by: Benson Leung <bleung@chromium.org>
Link: https://lore.kernel.org/r/20241213153543.v5.7.Ic61ced3cdfb5d6776435356061f12307da719829@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/platform/chrome/Kconfig

@@ -249,6 +249,7 @@ config CROS_EC_TYPEC
 	depends on USB_ROLE_SWITCH
 	default MFD_CROS_EC_DEV
 	select CROS_EC_TYPEC_ALTMODES if TYPEC_DP_ALTMODE
+	select CROS_EC_TYPEC_ALTMODES if TYPEC_TBT_ALTMODE
 	help
 	  If you say Y here, you get support for accessing Type C connector
 	  information from the Chrome OS EC.

drivers/platform/chrome/cros_ec_typec.c

@@ -303,18 +303,19 @@ static int cros_typec_register_port_altmodes(struct cros_typec_data *typec,
 
 	/*
 	 * Register TBT compatibility alt mode. The EC will not enter the mode
-	 * if it doesn't support it, so it's safe to register it unconditionally
-	 * here for now.
+	 * if it doesn't support it and it will not enter automatically by
+	 * design so we can use the |ap_driven_altmode| feature to check if we
+	 * should register it.
 	 */
-	memset(&desc, 0, sizeof(desc));
-	desc.svid = USB_TYPEC_TBT_SID;
-	desc.mode = TYPEC_ANY_MODE;
-	amode = typec_port_register_altmode(port->port, &desc);
-	if (IS_ERR(amode))
-		return PTR_ERR(amode);
-	port->port_altmode[CROS_EC_ALTMODE_TBT] = amode;
-	typec_altmode_set_drvdata(amode, port);
-	amode->ops = &port_amode_ops;
+	if (typec->ap_driven_altmode) {
+		memset(&desc, 0, sizeof(desc));
+		desc.svid = USB_TYPEC_TBT_SID;
+		desc.mode = TBT_MODE;
+		amode = cros_typec_register_thunderbolt(port, &desc);
+		if (IS_ERR(amode))
+			return PTR_ERR(amode);
+		port->port_altmode[CROS_EC_ALTMODE_TBT] = amode;
+	}
 
 	port->state.alt = NULL;
 	port->state.mode = TYPEC_STATE_USB;

drivers/platform/chrome/cros_typec_altmode.c

@@ -10,6 +10,7 @@
 #include <linux/mutex.h>
 #include <linux/workqueue.h>
 #include <linux/usb/typec_dp.h>
+#include <linux/usb/typec_tbt.h>
 #include <linux/usb/pd_vdo.h>
 
 #include "cros_typec_altmode.h"
@@ -72,6 +73,8 @@ static int cros_typec_altmode_enter(struct typec_altmode *alt, u32 *vdo)
 
 	if (adata->sid == USB_TYPEC_DP_SID)
 		req.mode_to_enter = CROS_EC_ALTMODE_DP;
+	else if (adata->sid == USB_TYPEC_TBT_SID)
+		req.mode_to_enter = CROS_EC_ALTMODE_TBT;
 	else
 		return -EOPNOTSUPP;
 
@@ -196,6 +199,56 @@ static int cros_typec_displayport_vdm(struct typec_altmode *alt, u32 header,
 	return 0;
 }
 
+static int cros_typec_thunderbolt_vdm(struct typec_altmode *alt, u32 header,
+				      const u32 *data, int count)
+{
+	struct cros_typec_altmode_data *adata = typec_altmode_get_drvdata(alt);
+
+	int cmd_type = PD_VDO_CMDT(header);
+	int cmd = PD_VDO_CMD(header);
+	int svdm_version;
+
+	svdm_version = typec_altmode_get_svdm_version(alt);
+	if (svdm_version < 0)
+		return svdm_version;
+
+	mutex_lock(&adata->lock);
+
+	switch (cmd_type) {
+	case CMDT_INIT:
+		if (PD_VDO_SVDM_VER(header) < svdm_version) {
+			typec_partner_set_svdm_version(adata->port->partner,
+						       PD_VDO_SVDM_VER(header));
+			svdm_version = PD_VDO_SVDM_VER(header);
+		}
+
+		adata->header = VDO(adata->sid, 1, svdm_version, cmd);
+		adata->header |= VDO_OPOS(adata->mode);
+
+		switch (cmd) {
+		case CMD_ENTER_MODE:
+			/* Don't respond to the enter mode vdm because it
+			 * triggers mux configuration. This is handled directly
+			 * by the cros_ec_typec driver so the Thunderbolt driver
+			 * doesn't need to be involved.
+			 */
+			break;
+		default:
+			adata->header |= VDO_CMDT(CMDT_RSP_ACK);
+			schedule_work(&adata->work);
+			break;
+		}
+
+		break;
+	default:
+		break;
+	}
+
+	mutex_unlock(&adata->lock);
+	return 0;
+}
+
+
 static int cros_typec_altmode_vdm(struct typec_altmode *alt, u32 header,
 				      const u32 *data, int count)
 {
@@ -207,6 +260,9 @@ static int cros_typec_altmode_vdm(struct typec_altmode *alt, u32 header,
 	if (adata->sid == USB_TYPEC_DP_SID)
 		return cros_typec_displayport_vdm(alt, header, data, count);
 
+	if (adata->sid == USB_TYPEC_TBT_SID)
+		return cros_typec_thunderbolt_vdm(alt, header, data, count);
+
 	return -EINVAL;
 }
 
@@ -283,3 +339,35 @@ cros_typec_register_displayport(struct cros_typec_port *port,
 	return alt;
 }
 #endif
+
+#if IS_ENABLED(CONFIG_TYPEC_TBT_ALTMODE)
+struct typec_altmode *
+cros_typec_register_thunderbolt(struct cros_typec_port *port,
+				struct typec_altmode_desc *desc)
+{
+	struct typec_altmode *alt;
+	struct cros_typec_altmode_data *adata;
+
+	alt = typec_port_register_altmode(port->port, desc);
+	if (IS_ERR(alt))
+		return alt;
+
+	adata = devm_kzalloc(&alt->dev, sizeof(*adata), GFP_KERNEL);
+	if (!adata) {
+		typec_unregister_altmode(alt);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	INIT_WORK(&adata->work, cros_typec_altmode_work);
+	adata->alt = alt;
+	adata->port = port;
+	adata->ap_mode_entry = true;
+	adata->sid = desc->svid;
+	adata->mode = desc->mode;
+
+	typec_altmode_set_ops(alt, &cros_typec_altmode_ops);
+	typec_altmode_set_drvdata(alt, adata);
+
+	return alt;
+}
+#endif

drivers/platform/chrome/cros_typec_altmode.h

@@ -34,4 +34,18 @@ static inline int cros_typec_displayport_status_update(struct typec_altmode *alt
 	return 0;
 }
 #endif
+
+#if IS_ENABLED(CONFIG_TYPEC_TBT_ALTMODE)
+struct typec_altmode *
+cros_typec_register_thunderbolt(struct cros_typec_port *port,
+				struct typec_altmode_desc *desc);
+#else
+static inline struct typec_altmode *
+cros_typec_register_thunderbolt(struct cros_typec_port *port,
+				struct typec_altmode_desc *desc)
+{
+	return typec_port_register_altmode(port->port, desc);
+}
+#endif
+
 #endif /* __CROS_TYPEC_ALTMODE_H__ */