system: Implement system safe mode

Basic implementation of system safe mode recovery.

System safe mode is a recovery mode that may be started after
a fault/panic. It allows the AP to collect info about the fault
and system state before the system resets

This CL includes support for Zephyr EC and legacy CrOS EC

BUG=b:249128225
BRANCH=None
TEST=./twister -s
external/platform/ec/zephyr/test/rw_safe_mode/rw_safe_mode.default
Manually tested on skyrim

Change-Id: I15139bb082011485b54e4ca7813839940bf5401a
Signed-off-by: Rob Barnes <robbarnes@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4029604
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Code-Coverage: Zoss <zoss-cl-coverage@prod.google.com>

1 files changed, 66 insertions, 0 deletions

diff --git a/include/system_safe_mode.h b/include/system_safe_mode.h
new file mode 100644
index 0000000000..a8bf23d5b0
--- /dev/null
+++ b/include/system_safe_mode.h
@@ -0,0 +1,66 @@
+/* Copyright 2022 The ChromiumOS Authors
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef __CROS_EC_SYSTEM_SAFE_MODE_H
+#define __CROS_EC_SYSTEM_SAFE_MODE_H
+
+/**
+ * Checks if running in system safe mode
+ *
+ * @return True if system is running in system safe mode
+ */
+bool system_is_in_safe_mode(void);
+
+/**
+ * Checks if command is allowed in system safe mode
+ *
+ * @return True if command is allowed in system safe mode
+ */
+bool command_is_allowed_in_safe_mode(int command);
+
+/**
+ * Checks if current task critical for system safe mode
+ *
+ * @return True if current task is safe mode critical
+ */
+bool current_task_is_safe_mode_critical(void);
+
+/**
+ * Disables tasks that are not critical for safe mode
+ *
+ * @return EC_SUCCESS or EC_xxx on error
+ */
+int disable_non_safe_mode_critical_tasks(void);
+
+/**
+ * Start system safe mode.
+ *
+ * System safe mode can only be started after a panic in RW image.
+ * It will only run briefly so the AP can capture EC state.
+ *
+ * @return EC_SUCCESS or EC_xxx on error
+ */
+int start_system_safe_mode(void);
+
+/**
+ * Schedules safe mode timeout.
+ *
+ * @return EC_SUCCESS or EC_xxx on error
+ */
+int schedule_system_safe_mode_timeout(void);
+
+/**
+ * This handler is called when safe mode times out.
+ */
+void handle_system_safe_mode_timeout(void);
+
+#ifdef TEST_BUILD
+/**
+ * Directly set safe mode flag. Only used in tests.
+ */
+void set_system_safe_mode(bool mode);
+#endif
+
+#endif /* __CROS_EC_SYSTEM_SAFE_MODE_H */