Commit f301bba0 authored by Peter Hilber's avatar Peter Hilber Committed by Sudeep Holla
Browse files

firmware: arm_scmi: Add message passing abstractions for transports 

Add abstractions for future transports using message passing, such as
virtio. Derive the abstractions from the shared memory abstractions.

Abstract the transport SDU through the opaque struct scmi_msg_payld.
Also enable the transport to determine all other required information
about the transport SDU.

Link: https://lore.kernel.org/r/20210803131024.40280-12-cristian.marussi@arm.com


Signed-off-by: default avatarPeter Hilber <peter.hilber@opensynergy.com>
[ Cristian: Adapted to new SCMI Kconfig layout, updated Copyrights ]
Signed-off-by: default avatarCristian Marussi <cristian.marussi@arm.com>
Signed-off-by: default avatarSudeep Holla <sudeep.holla@arm.com>
parent c92c3e38

drivers/firmware/arm_scmi/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -36,6 +36,12 @@ config ARM_SCMI_HAVE_SHMEM 
	  This declares whether a shared memory based transport for SCMI is

	  available.



config ARM_SCMI_HAVE_MSG

	bool

	help

	  This declares whether a message passing based transport for SCMI is

	  available.



config ARM_SCMI_TRANSPORT_MAILBOX

	bool "SCMI transport based on Mailbox"

	depends on MAILBOX

drivers/firmware/arm_scmi/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ scmi-driver-y = driver.o notify.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

scmi-transport-$(CONFIG_ARM_SCMI_HAVE_MSG) += msg.o

scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o voltage.o

scmi-module-objs := $(scmi-bus-y) $(scmi-driver-y) $(scmi-protocols-y) \

		    $(scmi-transport-y)

drivers/firmware/arm_scmi/common.h

+15 −0
Original line number Diff line number Diff line
@@ -432,6 +432,21 @@ void shmem_clear_channel(struct scmi_shared_mem __iomem *shmem); 
bool shmem_poll_done(struct scmi_shared_mem __iomem *shmem,

		     struct scmi_xfer *xfer);



/* declarations for message passing transports */

struct scmi_msg_payld;



/* Maximum overhead of message w.r.t. struct scmi_desc.max_msg_size */

#define SCMI_MSG_MAX_PROT_OVERHEAD (2 * sizeof(__le32))



size_t msg_response_size(struct scmi_xfer *xfer);

size_t msg_command_size(struct scmi_xfer *xfer);

void msg_tx_prepare(struct scmi_msg_payld *msg, struct scmi_xfer *xfer);

u32 msg_read_header(struct scmi_msg_payld *msg);

void msg_fetch_response(struct scmi_msg_payld *msg, size_t len,

			struct scmi_xfer *xfer);

void msg_fetch_notification(struct scmi_msg_payld *msg, size_t len,

			    size_t max_len, struct scmi_xfer *xfer);



void scmi_notification_instance_data_set(const struct scmi_handle *handle,

					 void *priv);

void *scmi_notification_instance_data_get(const struct scmi_handle *handle);

drivers/firmware/arm_scmi/msg.c

0 → 100644
+111 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * For transports using message passing.

 *

 * Derived from shm.c.

 *

 * Copyright (C) 2019-2021 ARM Ltd.

 * Copyright (C) 2020-2021 OpenSynergy GmbH

 */



#include <linux/types.h>



#include "common.h"



/*

 * struct scmi_msg_payld - Transport SDU layout

 *

 * The SCMI specification requires all parameters, message headers, return

 * arguments or any protocol data to be expressed in little endian format only.

 */

struct scmi_msg_payld {

	__le32 msg_header;

	__le32 msg_payload[];

};



/**

 * msg_command_size() - Actual size of transport SDU for command.

 *

 * @xfer: message which core has prepared for sending

 *

 * Return: transport SDU size.

 */

size_t msg_command_size(struct scmi_xfer *xfer)

{

	return sizeof(struct scmi_msg_payld) + xfer->tx.len;

}



/**

 * msg_response_size() - Maximum size of transport SDU for response.

 *

 * @xfer: message which core has prepared for sending

 *

 * Return: transport SDU size.

 */

size_t msg_response_size(struct scmi_xfer *xfer)

{

	return sizeof(struct scmi_msg_payld) + sizeof(__le32) + xfer->rx.len;

}



/**

 * msg_tx_prepare() - Set up transport SDU for command.

 *

 * @msg: transport SDU for command

 * @xfer: message which is being sent

 */

void msg_tx_prepare(struct scmi_msg_payld *msg, struct scmi_xfer *xfer)

{

	msg->msg_header = cpu_to_le32(pack_scmi_header(&xfer->hdr));

	if (xfer->tx.buf)

		memcpy(msg->msg_payload, xfer->tx.buf, xfer->tx.len);

}



/**

 * msg_read_header() - Read SCMI header from transport SDU.

 *

 * @msg: transport SDU

 *

 * Return: SCMI header

 */

u32 msg_read_header(struct scmi_msg_payld *msg)

{

	return le32_to_cpu(msg->msg_header);

}



/**

 * msg_fetch_response() - Fetch response SCMI payload from transport SDU.

 *

 * @msg: transport SDU with response

 * @len: transport SDU size

 * @xfer: message being responded to

 */

void msg_fetch_response(struct scmi_msg_payld *msg, size_t len,

			struct scmi_xfer *xfer)

{

	size_t prefix_len = sizeof(*msg) + sizeof(msg->msg_payload[0]);



	xfer->hdr.status = le32_to_cpu(msg->msg_payload[0]);

	xfer->rx.len = min_t(size_t, xfer->rx.len,

			     len >= prefix_len ? len - prefix_len : 0);



	/* Take a copy to the rx buffer.. */

	memcpy(xfer->rx.buf, &msg->msg_payload[1], xfer->rx.len);

}



/**

 * msg_fetch_notification() - Fetch notification payload from transport SDU.

 *

 * @msg: transport SDU with notification

 * @len: transport SDU size

 * @max_len: maximum SCMI payload size to fetch

 * @xfer: notification message

 */

void msg_fetch_notification(struct scmi_msg_payld *msg, size_t len,

			    size_t max_len, struct scmi_xfer *xfer)

{

	xfer->rx.len = min_t(size_t, max_len,

			     len >= sizeof(*msg) ? len - sizeof(*msg) : 0);



	/* Take a copy to the rx buffer.. */

	memcpy(xfer->rx.buf, msg->msg_payload, xfer->rx.len);

}