powerpc/85xx: verify the current address of CCSR before relocating it
Verify that CCSR is actually located where it is supposed to be before
we relocate it. This is useful in detecting U-Boot configurations that
are broken (e.g. an incorrect value for CONFIG_SYS_CCSRBAR_DEFAULT).
If the current value is wrong, we enter an infinite loop, which is handy
for debuggers.
Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/cpu/mpc85xx/start.S b/arch/powerpc/cpu/mpc85xx/start.S
index e519f35..d494528b 100644
--- a/arch/powerpc/cpu/mpc85xx/start.S
+++ b/arch/powerpc/cpu/mpc85xx/start.S
@@ -411,6 +411,33 @@
msync
tlbwe
+ /*
+ * We have a TLB for what we think is the current (old) CCSR. Let's
+ * verify that, otherwise we won't be able to move it.
+ * CONFIG_SYS_CCSRBAR_DEFAULT is always a 32-bit number, so we only
+ * need to compare the lower 32 bits of CCSRBAR on CoreNet systems.
+ */
+verify_old_ccsr:
+ lis r0, CONFIG_SYS_CCSRBAR_DEFAULT@h
+ ori r0, r0, CONFIG_SYS_CCSRBAR_DEFAULT@l
+#ifdef CONFIG_FSL_CORENET
+ lwz r1, 4(r9) /* CCSRBARL */
+#else
+ lwz r1, 0(r9) /* CCSRBAR, shifted right by 12 */
+ slwi r1, r1, 12
+#endif
+
+ cmpl 0, r0, r1
+
+ /*
+ * If the value we read from CCSRBARL is not what we expect, then
+ * enter an infinite loop. This will at least allow a debugger to
+ * halt execution and examine TLBs, etc. There's no point in going
+ * on.
+ */
+infinite_debug_loop:
+ bne infinite_debug_loop
+
#ifdef CONFIG_FSL_CORENET
#define CCSR_LAWBARH0 (CONFIG_SYS_CCSRBAR + 0x1000)