microblaze: Add checking mechanism for MSR instruction

It was necessary to use fourth parameter(r8) in early_printk
to show messages on console.

Signed-off-by: Michal Simek <monstr@monstr.eu>

1 files changed, 15 insertions, 2 deletions

diff --git a/arch/microblaze/kernel/head.S b/arch/microblaze/kernel/head.S
index e41c6ce2a7be..bfc7ea801cc4 100644
--- a/arch/microblaze/kernel/head.S
+++ b/arch/microblaze/kernel/head.S
@@ -55,6 +55,19 @@ ENTRY(_start)
         andi    r1, r1, ~2
         mts     rmsr, r1
 
+/*
+ * Here is checking mechanism which check if Microblaze has msr instructions
+ * We load msr and compare it with previous r1 value - if is the same,
+ * msr instructions works if not - cpu don't have them.
+ */
+        or      r8, r0, r0 /* 0 - I have msr instr, 1 - I don't have */
+        or      r12, r0, r0
+        msrset  r12, 0  /* set nothing - just read msr for test */
+        cmpu    r12, r12, r1
+        beqi    r12, 1f
+        ori     r8, r0, 1 /* I don't have msr */
+1:
+
 /* r7 may point to an FDT, or there may be one linked in.
    if it's in r7, we've got to save it away ASAP.
    We ensure r7 points to a valid FDT, just in case the bootloader
@@ -209,8 +222,8 @@ start_here:
          * Please see $(ARCH)/mach-$(SUBARCH)/setup.c for
          * the function.
          */
-        la      r8, r0, machine_early_init
-        brald   r15, r8
+        la      r9, r0, machine_early_init
+        brald   r15, r9
         nop
 
 #ifndef CONFIG_MMU