[U-Boot] [PATCH 10/24] arm: Add a prototype for save_boot_params_ret()

Simon Glass
2015-05-04T17:31:03Z

It is convenient for some boards to implement save_boot_params() in C rather
than assembler. Provide a way to return in this case.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

arch/arm/include/asm/system.h | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
index 2a5bed2..e584c3b 100644
--- a/arch/arm/include/asm/system.h
+++ b/arch/arm/include/asm/system.h
@@ -158,6 +158,22 @@ void flush_l3_cache(void);
* void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3);
*/

+/**
+ * save_boot_params_ret() - Return from save_boot_params()
+ *
+ * If you provide save_boot_params(), then you should jump back to this
+ * function when done. Try to preserve all registers.
+ *
+ * If your implementation of save_boot_params() is in C then it is acceptable
+ * to simply call save_boot_params_ret() at the end of your function. Since
+ * there is no link register set up, you cannot just exit the function. U-Boot
+ * will return to the (initialised) value of lr, and likely crash/hang.
+ *
+ * If your implementation of save_boot_params() is in assembler then you
+ * should use 'b' or 'bx' to return to save_boot_params_ret.
+ */
+void save_boot_params_ret(void);
+
#define isb() __asm__ __volatile__ ("" : : : "memory")

#define nop() __asm__ __volatile__("mov\tr0,r0\t@ nop\n\t");
--
2.2.0.rc0.207.ga3a616c