Blackfin arch: Print out debug info, as early as possible

Print out debug info, as early as possible - even before the
kernel initializes the interrupt vectors. Now we can print out debug
messages almost anytime during the boot process.

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

1 files changed, 41 insertions, 2 deletions

diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index e2239361cac3..a56b231d94ce 100644
--- a/arch/blackfin/mach-common/entry.S
+++ b/arch/blackfin/mach-common/entry.S
@@ -835,12 +835,13 @@ ENTRY(_ex_trace_buff_full)
         P2 = [sp++];
         P3 = [sp++];
         jump _return_from_exception;
+ENDPROC(_ex_trace_buff_full)
 
 #if CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN == 4
 .data
 #else
 .section .l1.data.B
-#endif
+#endif /* CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN */
 ENTRY(_trace_buff_offset)
         .long 0;
 ALIGN
@@ -848,7 +849,45 @@ ENTRY(_software_trace_buff)
         .rept ((1 << CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN)*256);
         .long 0
         .endr
-#endif
+#endif /* CONFIG_DEBUG_BFIN_HWTRACE_EXPAND */
+
+#if CONFIG_EARLY_PRINTK
+.section .init.text
+ENTRY(_early_trap)
+        SAVE_ALL_SYS
+        trace_buffer_stop(p0,r0);
+
+        /* Turn caches off, to ensure we don't get double exceptions */
+
+        P4.L = LO(IMEM_CONTROL);
+        P4.H = HI(IMEM_CONTROL);
+
+        R5 = [P4];              /* Control Register*/
+        BITCLR(R5,ENICPLB_P);
+        CLI R1;
+        SSYNC;          /* SSYNC required before writing to IMEM_CONTROL. */
+        .align 8;
+        [P4] = R5;
+        SSYNC;
+
+        P4.L = LO(DMEM_CONTROL);
+        P4.H = HI(DMEM_CONTROL);
+        R5 = [P4];
+        BITCLR(R5,ENDCPLB_P);
+        SSYNC;          /* SSYNC required before writing to DMEM_CONTROL. */
+        .align 8;
+        [P4] = R5;
+        SSYNC;
+        STI R1;
+
+        r0 = sp;        /* stack frame pt_regs pointer argument ==> r0 */
+        r1 = RETX;
+
+        SP += -12;
+        call _early_trap_c;
+        SP += 12;
+ENDPROC(_early_trap)
+#endif /* CONFIG_EARLY_PRINTK */
 
 /*
  * Put these in the kernel data section - that should always be covered by