init_rom: Add init_rom layer

Create a thin init_rom layer for accessing data objects linked into the
.init_rom section with the CONFIG_CHIP_INIT_ROM_REGION opton and
__init_rom attribute.

BUG=b:160330682
BRANCH=none
TEST=make buildall
TEST=Using the next CL, verify BMI260 config data can be read using both
memory mapped and indirect access.

Signed-off-by: Keith Short <keithshort@chromium.org>
Change-Id: I6cd311637e87cd10ac394ff75c4bfc16bbade3b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2335739
Reviewed-by: caveh jalali <caveh@chromium.org>
Reviewed-by: Abe Levkoy <alevkoy@chromium.org>
Commit-Queue: caveh jalali <caveh@chromium.org>

1 files changed, 53 insertions, 0 deletions

diff --git a/include/init_rom.h b/include/init_rom.h
new file mode 100644
index 0000000000..6d54e6aec4
--- /dev/null
+++ b/include/init_rom.h
@@ -0,0 +1,53 @@
+/* Copyright 2020 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.
+ */
+
+/*
+ * Routines for accessing data objects store in the .init_rom region.
+ * Enabled with the CONFIG_CHIP_INIT_ROM_REGION config option. Data
+ * objects are placed into the .init_rom region using the __init_rom attribute.
+ */
+
+#ifndef __CROS_EC_INIT_ROM_H
+#define __CROS_EC_INIT_ROM_H
+
+#include "stdbool.h"
+
+/**
+ * Get the memory mapped address of an .init_rom data object.
+ *
+ * @param offset	Address of the data object assigned by the linker.
+ *			This is effectively a flash offset when
+ *			CONFIG_CHIP_INIT_ROM_REGION is enabled, otherwise
+ *			it is a regular address.
+ * @param size	        Size of the data object.
+ *
+ * @return Pointer to data object in memory. Return NULL if the object
+ * is not memory mapped.
+ */
+const void *init_rom_map(const void *addr, int size);
+
+/**
+ * Unmaps an .init_rom data object. Must be called when init_rom_map() is
+ * successful.
+ *
+ * @param offset	Address of the data object assigned by the linker.
+ * @param size	        Size of the data object.
+ */
+void init_rom_unmap(const void *addr, int size);
+
+/**
+ * Copy an .init_rom data object into a RAM location. This routine must be used
+ * if init_rom_get_addr() returns NULL. This routine automatically handles
+ * locking of the flash.
+ *
+ * @param offset	Flash offset of the data object.
+ * @param size	        Size of the data object.
+ * @param data		Destination buffer for data.
+ *
+ * @return 0 on success.
+ */
+int init_rom_copy(int offset, int size, char *data);
+
+#endif /* __CROS_EC_INIT_ROM_H */