mec1322: add panic backup/restore function for the panic data

From spec, the ROM will use top 8KB memory during ROM execution.
To avoid PANIC_DATA_PTR be corrupted, we need to copy it to
the backup address and restore it at very early stage (RO little fw).

BUG=chrome-os-partner:61241
BRANCH=firmware-glados-7820.B
TEST=On EC console, use use command "crash assert"
     check the panic data is restored from backup address

Change-Id: I48fa7714295086abbca34139d6fb0f9c8daa3a93
Signed-off-by: Zhuo-hao Lee <zhuo-hao.lee@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/430577
Reviewed-by: Shawn N <shawnn@chromium.org>

4 files changed, 66 insertions, 0 deletions

diff --git a/chip/mec1322/lfw/ec_lfw.c b/chip/mec1322/lfw/ec_lfw.c
index 6824d10686..a7ed6ccc37 100644
--- a/chip/mec1322/lfw/ec_lfw.c
+++ b/chip/mec1322/lfw/ec_lfw.c
@@ -22,6 +22,7 @@
 #include "version.h"
 #include "hwtimer.h"
 #include "gpio_list.h"
+#include "panic_extra.h"
 
 #include "ec_lfw.h"
 
@@ -270,6 +271,11 @@ void lfw_main()
 		uart_puts("lfw-RO load\n");
 		spi_image_load(CONFIG_EC_PROTECTED_STORAGE_OFF +
 			       CONFIG_RO_STORAGE_OFF);
+		/*
+		 * Top 8KB of Data RAM will be used by ROM during system reboot.
+		 * Restore the panic data from the panic_backup.
+		 */
+		panic_data_restore();
 		/* fall through */
 	default:
 		MEC1322_VBAT_RAM(MEC1322_IMAGETYPE_IDX) =
diff --git a/chip/mec1322/panic_extra.h b/chip/mec1322/panic_extra.h
new file mode 100644
index 0000000000..e6f2c55ed7
--- /dev/null
+++ b/chip/mec1322/panic_extra.h
@@ -0,0 +1,46 @@
+/* Copyright 2017 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef __CROS_EC_PANIC_EXTRA_H
+#define __CROS_EC_PANIC_EXTRA_H
+
+/*
+* The backup address for the panic data.
+* Set it to CONFIG_RAM_BASE because the panic_backup is put
+* on this address by specifying section .bss.panic_extra
+*/
+
+#define PANIC_DATA_BACKUP_ADDRESS CONFIG_RAM_BASE
+
+/**
+ * Save the panic data to the panic_backup
+ */
+static inline void panic_data_backup(void)
+{
+	uint8_t *src_ptr = (uint8_t *)panic_get_data();
+	uint8_t *dest_ptr;
+	int num_bytes = sizeof(struct panic_data);
+
+	dest_ptr = (uint8_t *)PANIC_DATA_BACKUP_ADDRESS;
+	if (src_ptr) {
+		while (num_bytes--)
+			*dest_ptr++ = *src_ptr++;
+	}
+}
+
+/**
+ * Restore the panic data from the panic_backup
+ */
+static inline void panic_data_restore(void)
+{
+	uint8_t *src_ptr = (uint8_t *)PANIC_DATA_BACKUP_ADDRESS;
+	uint8_t *dest_ptr = (uint8_t *)PANIC_DATA_PTR;
+	int num_bytes = sizeof(struct panic_data);
+
+	while (num_bytes--)
+		*dest_ptr++ = *src_ptr++;
+}
+
+#endif /* __CROS_EC_PANIC_EXTRA_H */
diff --git a/chip/mec1322/system.c b/chip/mec1322/system.c
index c199332f57..3acc3a3acd 100644
--- a/chip/mec1322/system.c
+++ b/chip/mec1322/system.c
@@ -19,6 +19,10 @@
 #include "timer.h"
 #include "util.h"
 #include "spi.h"
+#include "panic_extra.h"
+
+__keep __attribute__ ((section(".bss.panic_extra")))
+struct panic_data panic_backup;
 
 /* Indices for hibernate data registers (RAM backed by VBAT) */
 enum hibdata_index {
@@ -78,6 +82,9 @@ int system_is_reboot_warm(void)
 
 void system_pre_init(void)
 {
+	/* make sure the panic_backup is located to the predefine address */
+	ASSERT(&panic_backup == (struct panic_data *)PANIC_DATA_BACKUP_ADDRESS);
+
 	/* Enable direct NVIC */
 	MEC1322_EC_INT_CTRL |= 1;
 
@@ -118,6 +125,12 @@ void _system_reset(int flags, int wake_from_hibernate)
 
 	chip_save_reset_flags(save_flags);
 
+	/*
+	 * Top 8KB of Data RAM will be used by ROM during system reboot.
+	 * So, copy the panic data to the panic_backup.
+	 */
+	panic_data_backup();
+
 	/* Trigger watchdog in 1ms */
 	MEC1322_WDG_LOAD = 1;
 	MEC1322_WDG_CTL |= 1;
diff --git a/core/cortex-m/ec.lds.S b/core/cortex-m/ec.lds.S
index 34c859b105..c8fc6efad7 100644
--- a/core/cortex-m/ec.lds.S
+++ b/core/cortex-m/ec.lds.S
@@ -237,6 +237,7 @@ SECTIONS
 	 */
         . = ALIGN(512);
         __bss_start = .;
+	*(.bss.panic_extra)
 	*(.bss.big_align)
 	/* Stacks must be 64-bit aligned */
         . = ALIGN(8);