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, 29 insertions, 2 deletions

diff --git a/include/case_closed_debug.h b/include/case_closed_debug.h
index 0b2ec8b468..77ad0f496f 100644
--- a/include/case_closed_debug.h
+++ b/include/case_closed_debug.h
@@ -46,6 +46,16 @@ enum ccd_mode ccd_get_mode(void);
 /******************************************************************************/
 /* New CCD "V1" configuration.  Eventually this will supersede the above code */
 
+/* Case-closed debugging state */
+enum ccd_state {
+	CCD_STATE_LOCKED = 0,
+	CCD_STATE_UNLOCKED,
+	CCD_STATE_OPENED,
+
+	/* Number of CCD states */
+	CCD_STATE_COUNT
+};
+
 /* Flags */
 enum ccd_flag {
 	/* Flags that can only be set internally; fill from bottom up */
@@ -128,8 +138,13 @@ enum ccd_capability {
  * Initialize CCD configuration at boot.
  *
  * This must be called before any command which gets/sets the configuration.
+ *
+ * @param state		Initial case-closed debugging state.  This should be
+ *			CCD_STATE_LOCKED unless this is a debug build, or if
+ *			a previous value is being restored after a low-power
+ *			resume.
  */
-void ccd_config_init(void);
+void ccd_config_init(enum ccd_state state);
 
 /**
  * Get a single CCD flag.
@@ -149,11 +164,23 @@ int ccd_get_flag(enum ccd_flag flag);
 int ccd_set_flag(enum ccd_flag flag, int value);
 
 /**
- * Check if a CCD capability is enabled in the current CCD mode
+ * Check if a CCD capability is enabled in the current CCD mode.
  *
  * @param cap		Capability to check
  * @return 1 if capability is enabled, 0 if disabled
  */
 int ccd_is_cap_enabled(enum ccd_capability cap);
 
+/**
+ * Get the current CCD state.
+ *
+ * This is intended for use by the board if it needs to back up the CCD state
+ * across low-power states and then restore it when calling ccd_config_init().
+ * Do NOT use this to gate debug capabilities; use ccd_is_cap_enabled() or
+ * ccd_get_flag() instead.
+ *
+ * @return The current CCD state.
+ */
+enum ccd_state ccd_get_state(void);
+
 #endif /* __CROS_EC_CASE_CLOSED_DEBUG_H */