firmware: arm_scmi: Add core raw transmission support

Add SCMI raw mode support which exposes a userspace interface to allow for
bare SCMI command injection and snooping from userspace.
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230118121426.492864-13-cristian.marussi@arm.comSigned-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/Kconfig

@@ -30,6 +30,21 @@ config ARM_SCMI_NEED_DEBUGFS
 	  which needs debugfs support. When selected causess the creation
 	  of a common SCMI debugfs root directory.
 
+config ARM_SCMI_RAW_MODE_SUPPORT
+	bool "Enable support for SCMI Raw transmission mode"
+	depends on DEBUG_FS
+	select ARM_SCMI_NEED_DEBUGFS
+	help
+	  Enable support for SCMI Raw transmission mode.
+
+	  If enabled allows the direct injection and snooping of SCMI bare
+	  messages through a dedicated debugfs interface.
+	  It is meant to be used by SCMI compliance/testing suites.
+
+	  When enabled regular SCMI drivers interactions are inhibited in
+	  order to avoid unexpected interactions with the SCMI Raw message
+	  flow. If unsure say N.
+
 config ARM_SCMI_HAVE_TRANSPORT
 	bool
 	help

drivers/firmware/arm_scmi/Makefile

@@ -3,6 +3,7 @@ scmi-bus-y = bus.o
 scmi-core-objs := $(scmi-bus-y)
 
 scmi-driver-y = driver.o notify.o
+scmi-driver-$(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT) += raw_mode.o
 scmi-transport-$(CONFIG_ARM_SCMI_HAVE_SHMEM) = shmem.o
 scmi-transport-$(CONFIG_ARM_SCMI_TRANSPORT_MAILBOX) += mailbox.o
 scmi-transport-$(CONFIG_ARM_SCMI_TRANSPORT_SMC) += smc.o

drivers/firmware/arm_scmi/driver.c

@@ -920,7 +920,8 @@ static void scmi_handle_response(struct scmi_chan_info *cinfo,
 	trace_scmi_msg_dump(info->id, cinfo->id, xfer->hdr.protocol_id,
 			    xfer->hdr.id,
 			    xfer->hdr.type == MSG_TYPE_DELAYED_RESP ?
-			    "DLYD" : "RESP",
+			    (!SCMI_XFER_IS_RAW(xfer) ? "DLYD" : "dlyd") :
+			    (!SCMI_XFER_IS_RAW(xfer) ? "RESP" : "resp"),
 			    xfer->hdr.seq, xfer->hdr.status,
 			    xfer->rx.buf, xfer->rx.len);
 
@@ -1045,7 +1046,8 @@ static int scmi_wait_for_reply(struct device *dev, const struct scmi_desc *desc,
 			/* Trace polled replies. */
 			trace_scmi_msg_dump(info->id, cinfo->id,
 					    xfer->hdr.protocol_id, xfer->hdr.id,
-					    "RESP",
+					    !SCMI_XFER_IS_RAW(xfer) ?
+					    "RESP" : "resp",
 					    xfer->hdr.seq, xfer->hdr.status,
 					    xfer->rx.buf, xfer->rx.len);
 		}

drivers/firmware/arm_scmi/raw_mode.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * System Control and Management Interface (SCMI) Message Protocol
+ * Raw mode support header.
+ *
+ * Copyright (C) 2022 ARM Ltd.
+ */
+#ifndef _SCMI_RAW_MODE_H
+#define _SCMI_RAW_MODE_H
+
+#include "common.h"
+
+enum {
+	SCMI_RAW_REPLY_QUEUE,
+	SCMI_RAW_NOTIF_QUEUE,
+	SCMI_RAW_ERRS_QUEUE,
+	SCMI_RAW_MAX_QUEUE
+};
+
+void *scmi_raw_mode_init(const struct scmi_handle *handle,
+			 struct dentry *top_dentry, int instance_id,
+			 const struct scmi_desc *desc, int tx_max_msg);
+void scmi_raw_mode_cleanup(void *raw);
+
+void scmi_raw_message_report(void *raw, struct scmi_xfer *xfer,
+			     unsigned int idx);
+void scmi_raw_error_report(void *raw, struct scmi_chan_info *cinfo,
+			   u32 msg_hdr, void *priv);
+
+#endif /* _SCMI_RAW_MODE_H */