chromeos: Add option to back up VBNV CMOS into flash

This adds a new kconfig option that will back up the VBNV data
from CMOS to flash, and restore it if the CMOS data is invalid
during boot.

This allows special flags to not get lost when power is lost,
RTC reset is triggered, or CMOS is corrupted.

BUG=chrome-os-partner:47915
BRANCH=glados
TEST=manually tested on chell:
1-boot and run "enable_dev_usb_boot"
2-reboot and check that it is enabled with crossystem
3-run "mosys nvram clear"
4-reboot and check that it is still enabled

Change-Id: I38103d100117da34471734a6dd31eb7058735c12
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 8a356e616c6885d5ae3b776691929675d48a28f9
Original-Change-Id: I06e7ddff7b272e579c704914a0cf8cc14d6994e8
Original-Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/324122
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/13600
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

3 files changed, 44 insertions, 0 deletions

diff --git a/src/vendorcode/google/chromeos/Kconfig b/src/vendorcode/google/chromeos/Kconfig
index 79d6918e96..4a889b1956 100644
--- a/src/vendorcode/google/chromeos/Kconfig
+++ b/src/vendorcode/google/chromeos/Kconfig
@@ -50,6 +50,14 @@ config CHROMEOS_VBNV_CMOS
 	help
 	  VBNV is stored in CMOS
 
+config CHROMEOS_VBNV_CMOS_BACKUP_TO_FLASH
+	bool "Backup Vboot non-volatile storage from CMOS to flash."
+	default n
+	depends on CHROMEOS_VBNV_CMOS
+	help
+	  Vboot non-volatile storage data will be backed up from CMOS to flash
+	  and restored from flash if the CMOS is invalid due to power loss.
+
 config CHROMEOS_VBNV_EC
 	bool "Vboot non-volatile storage in EC."
 	default n
diff --git a/src/vendorcode/google/chromeos/Makefile.inc b/src/vendorcode/google/chromeos/Makefile.inc
index ee8b50d9b6..7d62b5b530 100644
--- a/src/vendorcode/google/chromeos/Makefile.inc
+++ b/src/vendorcode/google/chromeos/Makefile.inc
@@ -28,6 +28,11 @@ verstage-$(CONFIG_CHROMEOS_VBNV_CMOS) += vbnv_cmos.c
 romstage-$(CONFIG_CHROMEOS_VBNV_CMOS) += vbnv_cmos.c
 ramstage-$(CONFIG_CHROMEOS_VBNV_CMOS) += vbnv_cmos.c
 
+bootblock-$(CONFIG_CHROMEOS_VBNV_CMOS_BACKUP_TO_FLASH) += vbnv_flash.c
+verstage-$(CONFIG_CHROMEOS_VBNV_CMOS_BACKUP_TO_FLASH) += vbnv_flash.c
+romstage-$(CONFIG_CHROMEOS_VBNV_CMOS_BACKUP_TO_FLASH) += vbnv_flash.c
+ramstage-$(CONFIG_CHROMEOS_VBNV_CMOS_BACKUP_TO_FLASH) += vbnv_flash.c
+
 bootblock-$(CONFIG_CHROMEOS_VBNV_EC) += vbnv_ec.c
 verstage-$(CONFIG_CHROMEOS_VBNV_EC) += vbnv_ec.c
 romstage-$(CONFIG_CHROMEOS_VBNV_EC) += vbnv_ec.c
diff --git a/src/vendorcode/google/chromeos/vbnv_cmos.c b/src/vendorcode/google/chromeos/vbnv_cmos.c
index e0d7ba1ea3..22acefa517 100644
--- a/src/vendorcode/google/chromeos/vbnv_cmos.c
+++ b/src/vendorcode/google/chromeos/vbnv_cmos.c
@@ -13,6 +13,8 @@
  * GNU General Public License for more details.
  */
 
+#include <bootstate.h>
+#include <console/console.h>
 #include <types.h>
 #include <pc80/mc146818rtc.h>
 #include "vbnv.h"
@@ -24,6 +26,21 @@ void read_vbnv_cmos(uint8_t *vbnv_copy)
 
 	for (i = 0; i < VBNV_BLOCK_SIZE; i++)
 		vbnv_copy[i] = cmos_read(CONFIG_VBNV_OFFSET + 14 + i);
+
+	if (IS_ENABLED(CONFIG_CHROMEOS_VBNV_CMOS_BACKUP_TO_FLASH)) {
+		if (verify_vbnv(vbnv_copy))
+			return;
+
+		printk(BIOS_INFO, "VBNV: CMOS invalid, restoring from flash\n");
+		read_vbnv_flash(vbnv_copy);
+
+		if (verify_vbnv(vbnv_copy)) {
+			save_vbnv_cmos(vbnv_copy);
+			printk(BIOS_INFO, "VBNV: Flash backup restored\n");
+		} else {
+			printk(BIOS_INFO, "VBNV: Restore from flash failed\n");
+		}
+	}
 }
 
 void save_vbnv_cmos(const uint8_t *vbnv_copy)
@@ -33,3 +50,17 @@ void save_vbnv_cmos(const uint8_t *vbnv_copy)
 	for (i = 0; i < VBNV_BLOCK_SIZE; i++)
 		cmos_write(vbnv_copy[i], CONFIG_VBNV_OFFSET + 14 + i);
 }
+
+#if IS_ENABLED(CONFIG_CHROMEOS_VBNV_CMOS_BACKUP_TO_FLASH)
+static void backup_vbnv_cmos(void *unused)
+{
+	uint8_t vbnv_cmos[VBNV_BLOCK_SIZE];
+
+	/* Read current VBNV from CMOS. */
+	read_vbnv_cmos(vbnv_cmos);
+
+	/* Save to flash, will only be saved if different. */
+	save_vbnv_flash(vbnv_cmos);
+}
+BOOT_STATE_INIT_ENTRY(BS_POST_DEVICE, BS_ON_EXIT, backup_vbnv_cmos, NULL);
+#endif