juno: Add SCPI interface and implement the SCP Ready command

The SCP Ready command is sent by the SCP to indicate that the BL3-0 RAM
Firmware image is successfully up and running.
Signed-off-by: Jon Medhurst <tixy@linaro.org>

plat/juno/scpi.c

+/*
+ * Copyright (c) 2014, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <arch_helpers.h>
+#include <mhu.h>
+#include <platform.h>
+#include <scpi.h>
+
+#define MHU_SECURE_SCP_TO_AP_PAYLOAD	(MHU_SECURE_BASE+0x0080)
+#define MHU_SECURE_AP_TO_SCP_PAYLOAD	(MHU_SECURE_BASE+0x0280)
+
+#define SIZE_SHIFT	20	/* Bit position for size value in MHU header */
+#define SIZE_MASK	0x1ff	/* Mask to extract size value in MHU header*/
+
+
+void *scpi_secure_message_start(void)
+{
+	mhu_secure_message_start();
+
+	/* Return address of payload area. */
+	return (void *)MHU_SECURE_AP_TO_SCP_PAYLOAD;
+}
+
+void scpi_secure_message_send(unsigned command, size_t size)
+{
+	/* Make sure payload can be seen by SCP */
+	if (MHU_PAYLOAD_CACHED)
+		flush_dcache_range(MHU_SECURE_AP_TO_SCP_PAYLOAD, size);
+
+	mhu_secure_message_send(command | (size << SIZE_SHIFT));
+}
+
+unsigned scpi_secure_message_receive(void **message_out, size_t *size_out)
+{
+	uint32_t response =  mhu_secure_message_wait();
+
+	/* Get size of payload */
+	size_t size = (response >> SIZE_SHIFT) & SIZE_MASK;
+
+	/* Clear size from response */
+	response &= ~(SIZE_MASK << SIZE_SHIFT);
+
+	/* Make sure we don't read stale data */
+	if (MHU_PAYLOAD_CACHED)
+		inv_dcache_range(MHU_SECURE_SCP_TO_AP_PAYLOAD, size);
+
+	if (size_out)
+		*size_out = size;
+
+	if (message_out)
+		*message_out = (void *)MHU_SECURE_SCP_TO_AP_PAYLOAD;
+
+	return response;
+}
+
+void scpi_secure_message_end(void)
+{
+	mhu_secure_message_end();
+}
+
+static void scpi_secure_send32(unsigned command, uint32_t message)
+{
+	*(__typeof__(message) *)scpi_secure_message_start() = message;
+	scpi_secure_message_send(command, sizeof(message));
+	scpi_secure_message_end();
+}
+
+int scpi_wait_ready(void)
+	{
+	/* Get a message from the SCP */
+	scpi_secure_message_start();
+	size_t size;
+	unsigned command = scpi_secure_message_receive(NULL, &size);
+	scpi_secure_message_end();
+
+	/* We are expecting 'SCP Ready', produce correct error if it's not */
+	spci_status response = SCP_OK;
+	if (command != SCPI_CMD_SCP_READY)
+		response = SCP_E_SUPPORT;
+	else if (size != 0)
+		response = SCP_E_SIZE;
+
+	/* Send our response back to SCP */
+	scpi_secure_send32(command, response);
+
+	return response == SCP_OK ? 0 : -1;
+	}

plat/juno/scpi.h

+/*
+ * Copyright (c) 2014, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __SCPI_H__
+#define __SCPI_H__
+
+#include <stdint.h>
+#include <stddef.h>
+
+extern void *scpi_secure_message_start(void);
+extern void scpi_secure_message_send(unsigned command, size_t size);
+extern unsigned scpi_secure_message_receive(void ** message_out, size_t *size_out);
+extern void scpi_secure_message_end(void);
+
+
+enum {
+	SCP_OK = 0,	/* Success */
+	SCP_E_PARAM,	/* Invalid parameter(s) */
+	SCP_E_ALIGN,	/* Invalid alignment */
+	SCP_E_SIZE,	/* Invalid size */
+	SCP_E_HANDLER,	/* Invalid handler or callback */
+	SCP_E_ACCESS,	/* Invalid access or permission denied */
+	SCP_E_RANGE,	/* Value out of range */
+	SCP_E_TIMEOUT,	/* Time out has ocurred */
+	SCP_E_NOMEM,	/* Invalid memory area or pointer */
+	SCP_E_PWRSTATE,	/* Invalid power state */
+	SCP_E_SUPPORT,	/* Feature not supported or disabled */
+};
+
+typedef uint32_t spci_status;
+
+typedef enum {
+	SCPI_CMD_SCP_READY = 0x01,
+} spci_command;
+
+extern int scpi_wait_ready(void);
+
+#endif	/* __SCPI_H__ */