rpi3: Detect board revision

Implement VideoCore mailbox interface driver and use it to get the board
revision identifier.

For now it is only used to print the model for debug purposes.

This wiki contains the documentation of the mailbox interface:

https://github.com/raspberrypi/firmware/wiki



Change-Id: I11943b99b52cc1409f4a195ebe58eb44ae5b1d6c
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

plat/rpi3/platform.mk

@@ -20,7 +20,8 @@ BL1_SOURCES		+=	drivers/io/io_fip.c			\
 				plat/common/aarch64/platform_mp_stack.S	\
 				plat/rpi3/aarch64/plat_helpers.S	\
 				plat/rpi3/rpi3_bl1_setup.c		\
-				plat/rpi3/rpi3_io_storage.c
+				plat/rpi3/rpi3_io_storage.c		\
+				plat/rpi3/rpi3_mbox.c
 
 BL2_SOURCES		+=	common/desc_image_load.c		\
 				drivers/io/io_fip.c			\

plat/rpi3/rpi3_bl1_setup.c

@@ -7,6 +7,7 @@
 #include <arch.h>
 #include <arch_helpers.h>
 #include <bl_common.h>
+#include <debug.h>
 #include <platform_def.h>
 #include <xlat_mmu_helpers.h>
 #include <xlat_tables_defs.h>
@@ -56,6 +57,39 @@ void bl1_plat_arch_setup(void)
 
 void bl1_platform_setup(void)
 {
+	uint32_t __unused rev;
+	int __unused rc;
+
+	rc = rpi3_vc_hardware_get_board_revision(&rev);
+
+	if (rc == 0) {
+		const char __unused *model, __unused *info;
+
+		switch (rev) {
+		case 0xA02082:
+			model = "Raspberry Pi 3 Model B";
+			info = "(1GB, Sony, UK)";
+			break;
+		case 0xA22082:
+			model = "Raspberry Pi 3 Model B";
+			info = "(1GB, Embest, China)";
+			break;
+		case 0xA020D3:
+			model = "Raspberry Pi 3 Model B+";
+			info = "(1GB, Sony, UK)";
+			break;
+		default:
+			model = "Unknown";
+			info = "(Unknown)";
+			ERROR("rpi3: Unknown board revision 0x%08x\n", rev);
+			break;
+		}
+
+		NOTICE("rpi3: Detected: %s %s [0x%08x]\n", model, info, rev);
+	} else {
+		ERROR("rpi3: Unable to detect board revision\n");
+	}
+
 	/* Initialise the IO layer and register platform IO devices */
 	plat_rpi3_io_setup();
 }

plat/rpi3/rpi3_hw.h

@@ -16,6 +16,27 @@
 #define RPI3_IO_BASE			ULL(0x3F000000)
 #define RPI3_IO_SIZE			ULL(0x01000000)
 
+/*
+ * ARM <-> VideoCore mailboxes
+ */
+#define RPI3_MBOX_OFFSET		ULL(0x0000B880)
+#define RPI3_MBOX_BASE			(RPI3_IO_BASE + RPI3_MBOX_OFFSET)
+/* VideoCore -> ARM */
+#define RPI3_MBOX0_READ_OFFSET		ULL(0x00000000)
+#define RPI3_MBOX0_PEEK_OFFSET		ULL(0x00000010)
+#define RPI3_MBOX0_SENDER_OFFSET	ULL(0x00000014)
+#define RPI3_MBOX0_STATUS_OFFSET	ULL(0x00000018)
+#define RPI3_MBOX0_CONFIG_OFFSET	ULL(0x0000001C)
+/* ARM -> VideoCore */
+#define RPI3_MBOX1_WRITE_OFFSET		ULL(0x00000020)
+#define RPI3_MBOX1_PEEK_OFFSET		ULL(0x00000030)
+#define RPI3_MBOX1_SENDER_OFFSET	ULL(0x00000034)
+#define RPI3_MBOX1_STATUS_OFFSET	ULL(0x00000038)
+#define RPI3_MBOX1_CONFIG_OFFSET	ULL(0x0000003C)
+/* Mailbox status constants */
+#define RPI3_MBOX_STATUS_FULL_MASK	U(0x80000000) /* Set if full */
+#define RPI3_MBOX_STATUS_EMPTY_MASK	U(0x40000000) /* Set if empty */
+
 /*
  * Power management, reset controller, watchdog.
  */

plat/rpi3/rpi3_mbox.c

+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <arch_helpers.h>
+#include <debug.h>
+#include <mmio.h>
+#include <platform_def.h>
+
+#include "rpi3_hw.h"
+
+/* This struct must be aligned to 16 bytes */
+typedef struct __packed __aligned(16) rpi3_mbox_request {
+	uint32_t	size; /* Buffer size in bytes */
+	uint32_t	code; /* Request/response code */
+	uint32_t	tags[0];
+} rpi3_mbox_request_t;
+
+#define RPI3_MBOX_BUFFER_SIZE		U(256)
+static uint8_t __aligned(16) rpi3_mbox_buffer[RPI3_MBOX_BUFFER_SIZE];
+
+/* Constants to perform a request/check the status of a request. */
+#define RPI3_MBOX_PROCESS_REQUEST	U(0x00000000)
+#define RPI3_MBOX_REQUEST_SUCCESSFUL	U(0x80000000)
+#define RPI3_MBOX_REQUEST_ERROR		U(0x80000001)
+
+/* Command constants */
+#define RPI3_TAG_HARDWARE_GET_BOARD_REVISION	U(0x00010002)
+#define RPI3_TAG_END				U(0x00000000)
+
+#define RPI3_TAG_REQUEST		U(0x00000000)
+#define RPI3_TAG_IS_RESPONSE		U(0x80000000) /* Set if response */
+#define RPI3_TAG_RESPONSE_LENGTH_MASK	U(0x7FFFFFFF)
+
+#define RPI3_CHANNEL_ARM_TO_VC		U(0x8)
+#define RPI3_CHANNEL_MASK		U(0xF)
+
+#define RPI3_MAILBOX_MAX_RETRIES	U(1000000)
+
+/*******************************************************************************
+ * Helpers to send requests to the VideoCore using the mailboxes.
+ ******************************************************************************/
+static void rpi3_vc_mailbox_request_send(void)
+{
+	uint32_t st, data;
+	uintptr_t resp_addr, addr;
+	unsigned int retries;
+
+	/* This is the location of the request buffer */
+	addr = (uintptr_t) &rpi3_mbox_buffer;
+
+	/* Make sure that the changes are seen by the VideoCore */
+	flush_dcache_range(addr, RPI3_MBOX_BUFFER_SIZE);
+
+	/* Wait until the outbound mailbox is empty */
+	retries = 0U;
+
+	do {
+		st = mmio_read_32(RPI3_MBOX_BASE + RPI3_MBOX1_STATUS_OFFSET);
+
+		retries++;
+		if (retries == RPI3_MAILBOX_MAX_RETRIES) {
+			ERROR("rpi3: mbox: Send request timeout\n");
+			return;
+		}
+
+	} while ((st & RPI3_MBOX_STATUS_EMPTY_MASK) == 0U);
+
+	/* Send base address of this message to start request */
+	mmio_write_32(RPI3_MBOX_BASE + RPI3_MBOX1_WRITE_OFFSET,
+		      RPI3_CHANNEL_ARM_TO_VC | (uint32_t) addr);
+
+	/* Wait until the inbound mailbox isn't empty */
+	retries = 0U;
+
+	do {
+		st = mmio_read_32(RPI3_MBOX_BASE + RPI3_MBOX0_STATUS_OFFSET);
+
+		retries++;
+		if (retries == RPI3_MAILBOX_MAX_RETRIES) {
+			ERROR("rpi3: mbox: Receive response timeout\n");
+			return;
+		}
+
+	} while ((st & RPI3_MBOX_STATUS_EMPTY_MASK) != 0U);
+
+	/* Get location and channel */
+	data = mmio_read_32(RPI3_MBOX_BASE + RPI3_MBOX0_READ_OFFSET);
+
+	if ((data & RPI3_CHANNEL_MASK) != RPI3_CHANNEL_ARM_TO_VC) {
+		ERROR("rpi3: mbox: Wrong channel: 0x%08x\n", data);
+		panic();
+	}
+
+	resp_addr = (uintptr_t)(data & ~RPI3_CHANNEL_MASK);
+	if (addr != resp_addr) {
+		ERROR("rpi3: mbox: Unexpected address: 0x%08x\n", data);
+		panic();
+	}
+
+	/* Make sure that the data seen by the CPU is up to date */
+	inv_dcache_range(addr, RPI3_MBOX_BUFFER_SIZE);
+}
+
+/*******************************************************************************
+ * Request board revision. Returns the revision and 0 on success, -1 on error.
+ ******************************************************************************/
+int rpi3_vc_hardware_get_board_revision(uint32_t *revision)
+{
+	uint32_t tag_request_size = sizeof(uint32_t);
+	rpi3_mbox_request_t *req = (rpi3_mbox_request_t *) rpi3_mbox_buffer;
+
+	assert(revision != NULL);
+
+	VERBOSE("rpi3: mbox: Sending request at %p\n", (void *)req);
+
+	req->size = sizeof(rpi3_mbox_buffer);
+	req->code = RPI3_MBOX_PROCESS_REQUEST;
+
+	req->tags[0] = RPI3_TAG_HARDWARE_GET_BOARD_REVISION;
+	req->tags[1] = tag_request_size; /* Space available for the response */
+	req->tags[2] = RPI3_TAG_REQUEST;
+	req->tags[3] = 0; /* Placeholder for the response */
+
+	req->tags[4] = RPI3_TAG_END;
+
+	rpi3_vc_mailbox_request_send();
+
+	if (req->code != RPI3_MBOX_REQUEST_SUCCESSFUL) {
+		ERROR("rpi3: mbox: Code = 0x%08x\n", req->code);
+		return -1;
+	}
+
+	if (req->tags[2] != (RPI3_TAG_IS_RESPONSE | tag_request_size)) {
+		ERROR("rpi3: mbox: get board revision failed (0x%08x)\n",
+		      req->tags[2]);
+		return -1;
+	}
+
+	*revision = req->tags[3];
+
+	return 0;
+}

plat/rpi3/rpi3_private.h

@@ -33,4 +33,7 @@ uint32_t rpi3_get_spsr_for_bl33_entry(void);
 /* IO storage utility functions */
 void plat_rpi3_io_setup(void);
 
+/* VideoCore firmware commands */
+int rpi3_vc_hardware_get_board_revision(uint32_t *revision);
+
 #endif /*__RPI3_PRIVATE_H__ */