platform/chrome: cros_ec_typec: Add initial VDM support

Add ops to support USB PD VDM (Vendor Defined Message) from the port
driver. This enables the port driver to interface with alternate mode
drivers and communicate with connected peripherals.

The initial support just contains an implementation of the Enter
Mode command.

Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Prashant Malani <pmalani@chromium.org>
[pmalani: Fixed trivial conflict in Makefile]
Reviewed-by: Benson Leung <bleung@chromium.org>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20221228004648.793339-9-pmalani@chromium.org

MAINTAINERS

@@ -5007,6 +5007,7 @@ L:	chrome-platform@lists.linux.dev
 S:	Maintained
 F:	drivers/platform/chrome/cros_ec_typec.*
 F:	drivers/platform/chrome/cros_typec_switch.c
+F:	drivers/platform/chrome/cros_typec_vdm.*
 
 CHROMEOS EC USB PD NOTIFY DRIVER
 M:	Prashant Malani <pmalani@chromium.org>

drivers/platform/chrome/Makefile

@@ -17,7 +17,7 @@ obj-$(CONFIG_CROS_EC_RPMSG)		+= cros_ec_rpmsg.o
 obj-$(CONFIG_CROS_EC_SPI)		+= cros_ec_spi.o
 obj-$(CONFIG_CROS_EC_UART)		+= cros_ec_uart.o
 cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_mec.o
-cros-ec-typec-objs			:= cros_ec_typec.o
+cros-ec-typec-objs			:= cros_ec_typec.o cros_typec_vdm.o
 obj-$(CONFIG_CROS_EC_TYPEC)		+= cros-ec-typec.o
 obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
 obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o cros_ec_trace.o

drivers/platform/chrome/cros_ec_typec.c

@@ -17,6 +17,7 @@
 #include <linux/usb/typec_tbt.h>
 
 #include "cros_ec_typec.h"
+#include "cros_typec_vdm.h"
 
 #define DRV_NAME "cros-ec-typec"
 
@@ -272,6 +273,7 @@ static int cros_typec_register_port_altmodes(struct cros_typec_data *typec,
 		return PTR_ERR(amode);
 	port->port_altmode[CROS_EC_ALTMODE_DP] = amode;
 	typec_altmode_set_drvdata(amode, port);
+	amode->ops = &port_amode_ops;
 
 	/*
 	 * Register TBT compatibility alt mode. The EC will not enter the mode
@@ -286,6 +288,7 @@ static int cros_typec_register_port_altmodes(struct cros_typec_data *typec,
 		return PTR_ERR(amode);
 	port->port_altmode[CROS_EC_ALTMODE_TBT] = amode;
 	typec_altmode_set_drvdata(amode, port);
+	amode->ops = &port_amode_ops;
 
 	port->state.alt = NULL;
 	port->state.mode = TYPEC_STATE_USB;

drivers/platform/chrome/cros_typec_vdm.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * USB Power Delivery Vendor Defined Message (VDM) support code.
+ *
+ * Copyright 2023 Google LLC
+ * Author: Prashant Malani <pmalani@chromium.org>
+ */
+
+#include <linux/module.h>
+#include <linux/platform_data/cros_ec_commands.h>
+#include <linux/usb/pd_vdo.h>
+
+#include "cros_ec_typec.h"
+#include "cros_typec_vdm.h"
+
+static int cros_typec_port_amode_enter(struct typec_altmode *amode, u32 *vdo)
+{
+	struct cros_typec_port *port = typec_altmode_get_drvdata(amode);
+	struct ec_params_typec_control req = {
+		.port = port->port_num,
+		.command = TYPEC_CONTROL_COMMAND_SEND_VDM_REQ,
+	};
+	struct typec_vdm_req vdm_req = {};
+	u32 hdr;
+
+	hdr = VDO(amode->svid, 1, SVDM_VER_2_0, CMD_ENTER_MODE);
+	hdr |= VDO_OPOS(amode->mode);
+
+	vdm_req.vdm_data[0] = hdr;
+	vdm_req.vdm_data_objects = 1;
+	vdm_req.partner_type = TYPEC_PARTNER_SOP;
+	req.vdm_req_params = vdm_req;
+
+	dev_dbg(port->typec_data->dev, "Sending EnterMode VDM, hdr: %x, port: %d\n",
+		hdr, port->port_num);
+
+	return cros_ec_cmd(port->typec_data->ec, 0, EC_CMD_TYPEC_CONTROL, &req,
+			   sizeof(req), NULL, 0);
+}
+
+struct typec_altmode_ops port_amode_ops = {
+	.enter = cros_typec_port_amode_enter,
+};

drivers/platform/chrome/cros_typec_vdm.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __CROS_TYPEC_VDM__
+#define __CROS_TYPEC_VDM__
+
+#include <linux/usb/typec_altmode.h>
+
+extern struct typec_altmode_ops port_amode_ops;
+
+#endif /*  __CROS_TYPEC_VDM__ */