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authorSimon Glass <sjg@chromium.org>2015-05-13 07:02:24 -0600
committerSimon Glass <sjg@chromium.org>2015-06-10 19:26:54 -0600
commit32ba8952cb449f8b151c4c1a27b9e9c3b4995dee (patch)
tree6d3096b9cfc1a51bd5dcd7aededdc5ed0978aabb /include
parent0c5dd9ae2f2e731c5c961fd92fa974aaa3cbdc27 (diff)
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arm: spl: Add an API to detect when U-Boot is started from SPL
For secure boot systems it is common to have a read-only U-Boot which starts the machine and jumps to a read-write U-Boot for actual booting the OS. This allows the read-write U-Boot to be upgraded without risk of permanently bricking the machine. In the event that the read-write U-Boot is corrupted, the read-only U-Boot can detect this with a checksum and boot into a recovery flow. To support this, add a way to detect when U-Boot is run from SPL as opposed to some other method, such as booted directly (no SPL) or started from another source (e.g. a primary U-Boot). This works by putting a special value in r0. For now we rely on board-specific code to actually check the register and set a flag. At some point this could be generalised, perhaps by using a spare register and passing a flag to _main and/or board_init_f(). This commit does not implement any feature, but merely provides the API for boards to implement. Signed-off-by: Simon Glass <sjg@chromium.org>
Diffstat (limited to 'include')
-rw-r--r--include/spl.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/spl.h b/include/spl.h
index b2e5bf7..d19940f 100644
--- a/include/spl.h
+++ b/include/spl.h
@@ -11,6 +11,8 @@
#include <linux/compiler.h>
#include <asm/spl.h>
+/* Value in r0 indicates we booted from U-Boot */
+#define UBOOT_NOT_LOADED_FROM_SPL 0x13578642
/* Boot type */
#define MMCSD_MODE_UNDEFINED 0
@@ -82,4 +84,15 @@ int spl_load_image_ext_os(block_dev_desc_t *block_dev, int partition);
#ifdef CONFIG_SPL_BOARD_INIT
void spl_board_init(void);
#endif
+
+/**
+ * spl_was_boot_source() - check if U-Boot booted from SPL
+ *
+ * This will normally be true, but if U-Boot jumps to second U-Boot, it will
+ * be false. This should be implemented by board-specific code.
+ *
+ * @return true if U-Boot booted from SPL, else false
+ */
+bool spl_was_boot_source(void);
+
#endif