zephyr: cortex-m: Add software panic support

Software panic implementation is needed to support system.c's
system_common_pre_init. For reference, this code was taken from
core/cortex-m/panic.c.

BRANCH=none
BUG=b:167392037
TEST=zmake testall

Change-Id: I91232b297c9933d48e3b7c59d7d8befe84cdecc5
Signed-off-by: Yuval Peress <peress@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2693687
Reviewed-by: Keith Short <keithshort@chromium.org>

6 files changed, 98 insertions, 2 deletions

diff --git a/include/panic.h b/include/panic.h
index 664c3c58f0..4d462a1bfb 100644
--- a/include/panic.h
+++ b/include/panic.h
@@ -192,7 +192,15 @@ void panic_set_reason(uint32_t reason, uint32_t info, uint8_t exception);
  * Retrieve the currently stored panic reason + info.
  */
 void panic_get_reason(uint32_t *reason, uint32_t *info, uint8_t *exception);
-#endif
+
+#ifdef CONFIG_ZEPHYR
+/**
+ * Zephyr utility for architecture specific logic to run when setting panic
+ * reason.
+ */
+void arch_panic_set_reason(uint32_t reason, uint32_t info, uint8_t exception);
+#endif /* CONFIG_ZEPHYR */
+#endif /* CONFIG_SOFTWARE_PANIC */
 
 /**
  * Enable/disable bus fault handler
diff --git a/zephyr/shim/CMakeLists.txt b/zephyr/shim/CMakeLists.txt
index 3add679c23..e36101756a 100644
--- a/zephyr/shim/CMakeLists.txt
+++ b/zephyr/shim/CMakeLists.txt
@@ -2,5 +2,6 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-add_subdirectory("src")
 add_subdirectory("chip")
+add_subdirectory("core")
+add_subdirectory("src")
diff --git a/zephyr/shim/core/CMakeLists.txt b/zephyr/shim/core/CMakeLists.txt
new file mode 100644
index 0000000000..e1b13f21f4
--- /dev/null
+++ b/zephyr/shim/core/CMakeLists.txt
@@ -0,0 +1,7 @@
+# Copyright 2021 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+if (DEFINED CONFIG_CPU_CORTEX_M)
+    add_subdirectory(cortex-m)
+endif()
diff --git a/zephyr/shim/core/cortex-m/CMakeLists.txt b/zephyr/shim/core/cortex-m/CMakeLists.txt
new file mode 100644
index 0000000000..9dc2defce4
--- /dev/null
+++ b/zephyr/shim/core/cortex-m/CMakeLists.txt
@@ -0,0 +1,5 @@
+# Copyright 2021 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+zephyr_sources_ifdef(CONFIG_PLATFORM_EC_SOFTWARE_PANIC software_panic.c)
diff --git a/zephyr/shim/core/cortex-m/software_panic.c b/zephyr/shim/core/cortex-m/software_panic.c
new file mode 100644
index 0000000000..6bedce5506
--- /dev/null
+++ b/zephyr/shim/core/cortex-m/software_panic.c
@@ -0,0 +1,28 @@
+/* Copyright 2021 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/*
+ * Content of this file are taken directly from
+ * platform/ec/core/cortex-m/panic.c. The code is replicated deliberately to
+ * allow future refactors into Zephyr specific APIs.
+ */
+
+#include "common.h"
+#include "panic.h"
+
+void software_panic(uint32_t reason, uint32_t info)
+{
+	/* TODO(b:180422087) Zephyrize this. */
+	__asm__("mov " STRINGIFY(SOFTWARE_PANIC_INFO_REG) ", %0\n"
+		"mov " STRINGIFY(SOFTWARE_PANIC_REASON_REG) ", %1\n"
+		"bl exception_panic\n"
+		: : "r"(info), "r"(reason));
+	__builtin_unreachable();
+}
+
+void arch_panic_set_reason(uint32_t reason, uint32_t info, uint8_t exception)
+{
+	/* No cortex-m architecture specific logic. */
+}
diff --git a/zephyr/shim/src/panic.c b/zephyr/shim/src/panic.c
index e556fcbcca..6d39ada928 100644
--- a/zephyr/shim/src/panic.c
+++ b/zephyr/shim/src/panic.c
@@ -9,6 +9,7 @@
 #include <logging/log_ctrl.h>
 #include <zephyr.h>
 
+#include "common.h"
 #include "panic.h"
 
 /*
@@ -35,10 +36,21 @@
 	M(basic.lr, cm.frame[5], lr)  \
 	M(basic.pc, cm.frame[6], pc)  \
 	M(basic.xpsr, cm.frame[7], xpsr)
+#define PANIC_REG_EXCEPTION(pdata) pdata->cm.regs[1]
+#define PANIC_REG_REASON(pdata) pdata->cm.regs[3]
+#define PANIC_REG_INFO(pdata) pdata->cm.regs[4]
 #else
 /* Not implemented for this arch */
 #define PANIC_ARCH 0
 #define PANIC_REG_LIST(M)
+#ifdef CONFIG_PLATFORM_EC_SOFTWARE_PANIC
+static uint8_t placeholder_exception_reg;
+static uint32_t placeholder_reason_reg;
+static uint32_t placeholder_info_reg;
+#define PANIC_REG_EXCEPTION(unused) placeholder_exception_reg
+#define PANIC_REG_REASON(unused) placeholder_reason_reg
+#define PANIC_REG_INFO(unused) placeholder_info_reg
+#endif /* CONFIG_PLATFORM_EC_SOFTWARE_PANIC */
 #endif
 
 /* Macros to be applied to PANIC_REG_LIST as M */
@@ -78,3 +90,38 @@ void k_sys_fatal_error_handler(unsigned int reason, const z_arch_esf_t *esf)
 	k_fatal_halt(reason);
 	CODE_UNREACHABLE;
 }
+
+#ifdef CONFIG_PLATFORM_EC_SOFTWARE_PANIC
+void panic_set_reason(uint32_t reason, uint32_t info, uint8_t exception)
+{
+	struct panic_data * const pdata = get_panic_data_write();
+
+	/* Setup panic data structure */
+	memset(pdata, 0, CONFIG_PANIC_DATA_SIZE);
+	pdata->magic = PANIC_DATA_MAGIC;
+	pdata->struct_size = CONFIG_PANIC_DATA_SIZE;
+	pdata->struct_version = 2;
+	pdata->arch = PANIC_ARCH;
+
+	/* Log panic cause */
+	PANIC_REG_EXCEPTION(pdata) = exception;
+	PANIC_REG_REASON(pdata) = reason;
+	PANIC_REG_INFO(pdata) = info;
+
+	/* Allow architecture specific logic */
+	arch_panic_set_reason(reason, info, exception);
+}
+
+void panic_get_reason(uint32_t *reason, uint32_t *info, uint8_t *exception)
+{
+	struct panic_data * const pdata = panic_get_data();
+
+	if (pdata && pdata->struct_version == 2) {
+		*exception = PANIC_REG_EXCEPTION(pdata);
+		*reason = PANIC_REG_REASON(pdata);
+		*info = PANIC_REG_INFO(pdata);
+	} else {
+		*exception = *reason = *info = 0;
+	}
+}
+#endif /* CONFIG_PLATFORM_EC_SOFTWARE_PANIC */