cr50: Preserve CCD state across deep sleep

Define two bits in a long-life register to hold the current CCD state
across deep sleep.  Update the bits on CCD config change, and restore
them on init.

This is necessary because Cr50 loses RAM contents on deep sleep.  It
would be really inconvenient to open CCD, get a cup of coffee, and
come back to find CCD has locked again because Cr50 was idle too long.

See go/cr50-ccd-wp for more information.

BUG=b:62537474
BRANCH=cr50
TEST=manual with CR50_DEV=1 build
     ccdinfo --> state=opened
     idle d
     ccdunlock
     ccdinfo --> state=unlocked
     (wait for deep sleep)
     sysinfo --> reset flags = hibernate wake-pin
     ccdinfo --> state=unlocked
     reboot
     sysinfo --> reset flags = hard
     ccdinfo --> state=opened

Change-Id: I7864f374af5c159bc9691b094958fb030f3cb8ad
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/575996
Reviewed-by: Mary Ruthven <mruthven@chromium.org>

1 files changed, 12 insertions, 15 deletions

diff --git a/common/ccd_config.c b/common/ccd_config.c
index 2c465c6d68..021ae121f3 100644
--- a/common/ccd_config.c
+++ b/common/ccd_config.c
@@ -14,6 +14,7 @@
 #include "nvmem_vars.h"
 #include "physical_presence.h"
 #include "system.h"
+#include "system_chip.h"
 #include "task.h"
 #include "timer.h"
 #include "trng.h"
@@ -21,15 +22,6 @@
 #define CPRINTS(format, args...) cprints(CC_CCD, format, ## args)
 #define CPRINTF(format, args...) cprintf(CC_CCD, format, ## args)
 
-enum ccd_state {
-	CCD_STATE_LOCKED = 0,
-	CCD_STATE_UNLOCKED,
-	CCD_STATE_OPENED,
-
-	/* Number of CCD states */
-	CCD_STATE_COUNT
-};
-
 /* Restriction state for ccdunlock when no password is set */
 enum ccd_unlock_restrict {
 	/* Unrestricted */
@@ -151,12 +143,7 @@ static const char *ccd_state_names[CCD_STATE_COUNT] = {
 static const char *ccd_cap_state_names[CCD_CAP_STATE_COUNT] = {
 	"Default", "Always", "UnlessLocked", "IfOpened"};
 
-#ifdef CONFIG_CASE_CLOSED_DEBUG_V1_UNSAFE
-static enum ccd_state ccd_state = CCD_STATE_OPENED;
-#else
 static enum ccd_state ccd_state = CCD_STATE_LOCKED;
-#endif
-
 static struct ccd_config config;
 static uint8_t ccd_config_loaded;
 static struct mutex ccd_config_mutex;
@@ -630,8 +617,13 @@ static void ccd_testlab_toggle(void)
 /******************************************************************************/
 /* External interface */
 
-void ccd_config_init(void)
+void ccd_config_init(enum ccd_state state)
 {
+	/* Set initial state, after making sure it's a valid one */
+	if (state != CCD_STATE_UNLOCKED && state != CCD_STATE_OPENED)
+		state = CCD_STATE_LOCKED;
+	ccd_state = state;
+
 	ccd_load_config();
 }
 
@@ -683,6 +675,11 @@ int ccd_is_cap_enabled(enum ccd_capability cap)
 	}
 }
 
+enum ccd_state ccd_get_state(void)
+{
+	return ccd_state;
+}
+
 /******************************************************************************/
 /* Console commands */