it8xxx2: add support option CONFIG_PRESERVE_LOGS

On it8xxx2 chips, assert WRST# to reset itself will clear memory
content to default value, this is a HW mechanism. So if
CONFIG_PRESERVE_LOGS and CONFIG_IT83XX_HARD_RESET_BY_GPG1 are enabled
at the same time, we have to save EC logs into flash before reset.
We will restore logs from flash on the next initialization before
jumping to main routine.

BUG=b:183899510, b:183466169
BRANCH=none
TEST=1) __image_size is same as ec.RW.bin size.
     2) buildall.
     3) manually verify reboot, poweroff, and sysjump from AP console:
localhost ~ # ectool uptimeinfo
EC uptime: 64.755 seconds
AP resets since EC boot: 0
Most recent AP reset causes:
EC reset flags at last EC boot: reset-pin | power-on
localhost ~ # reboot
...
localhost ~ # ectool uptimeinfo
EC uptime: 19.334 seconds
AP resets since EC boot: 0
Most recent AP reset causes:
	71.609: reset: at AP's request
EC reset flags at last EC boot: reset-pin | power-on | hard
localhost ~ # poweroff
...
localhost ~ # ectool uptimeinfo
EC uptime: 20.627 seconds
AP resets since EC boot: 0
Most recent AP reset causes:
	71.609: reset: at AP's request
	32.149: reset: at AP's request
EC reset flags at last EC boot: reset-pin | power-on | hard
localhost ~ # ectool reboot_ec RW
localhost ~ # ectool uptimeinfo
EC uptime: 37.998 seconds
AP resets since EC boot: 0
Most recent AP reset causes:
	71.609: reset: at AP's request
	32.149: reset: at AP's request
EC reset flags at last EC boot: reset-pin | power-on | sysjump | hard
localhost ~ #

Change-Id: I76b5f172b7728dc5ce9bf3a965cb7b2d638f8fc3
Signed-off-by: Dino Li <Dino.Li@ite.com.tw>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2794322
Reviewed-by: Eric Yilun Lin <yllin@chromium.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/chip/it83xx/system.c b/chip/it83xx/system.c
index 25907d1191..2f6fbd504b 100644
--- a/chip/it83xx/system.c
+++ b/chip/it83xx/system.c
@@ -13,6 +13,7 @@
 #include "hooks.h"
 #include "host_command.h"
 #include "intc.h"
+#include "link_defs.h"
 #include "registers.h"
 #include "system.h"
 #include "task.h"
@@ -260,6 +261,16 @@ void chip_bram_valid(void)
 		BRAM_VALID_FLAGS2 = BRAM_VALID_MAGIC_FIELD2;
 		BRAM_VALID_FLAGS3 = BRAM_VALID_MAGIC_FIELD3;
 	}
+
+#if defined(CONFIG_PRESERVE_LOGS) && defined(CONFIG_IT83XX_HARD_RESET_BY_GPG1)
+	if (BRAM_EC_LOG_STATUS == EC_LOG_SAVED_IN_FLASH) {
+		/* Restore EC logs from flash. */
+		memcpy((void *)__preserved_logs_start,
+			(const void *)CHIP_FLASH_PRESERVE_LOGS_BASE,
+			(uintptr_t)__preserved_logs_size);
+	}
+	BRAM_EC_LOG_STATUS = 0;
+#endif
 }
 
 void system_pre_init(void)
@@ -296,6 +307,15 @@ void system_reset(int flags)
 		cflush();
 	}
 
+#if defined(CONFIG_PRESERVE_LOGS) && defined(CONFIG_IT83XX_HARD_RESET_BY_GPG1)
+	/* Saving EC logs into flash before reset. */
+	flash_physical_erase(CHIP_FLASH_PRESERVE_LOGS_BASE,
+		CHIP_FLASH_PRESERVE_LOGS_SIZE);
+	flash_physical_write(CHIP_FLASH_PRESERVE_LOGS_BASE,
+		(uintptr_t)__preserved_logs_size, __preserved_logs_start);
+	BRAM_EC_LOG_STATUS = EC_LOG_SAVED_IN_FLASH;
+#endif
+
 	/* Disable interrupts to avoid task swaps during reboot. */
 	interrupt_disable();