Blackfin arch: allow people to select the feature that is unavailable to the kernel

 - allow people to select the feature that is unavailable to the kernel: NMI, JTAG, or CYCLES.
 - change default NMI handler to simply dump hardware trace buffer.
 - remove default NMI handler completely as calling into kernel code is not safe
   move example handler to wiki so people dont haphazardly copy and paste this stuff thinking its safe

Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/arch/blackfin/mach-bf537/head.S b/arch/blackfin/mach-bf537/head.S
index 6dbcb77c8d36..0836bfdcc6c5 100644
--- a/arch/blackfin/mach-bf537/head.S
+++ b/arch/blackfin/mach-bf537/head.S
@@ -51,10 +51,12 @@ __INIT
 ENTRY(__start)
         /* R0: argument of command line string, passed from uboot, save it */
         R7 = R0;
-        /* Set the SYSCFG register:
-         * Enable Cycle Counter and Nesting Of Interrupts (3rd Bit)
-         */
-        R0 = 0x36;
+        /* Enable Cycle Counter and Nesting Of Interrupts */
+#ifdef CONFIG_BFIN_SCRATCH_REG_CYCLES
+        R0 = SYSCFG_SNEN;
+#else
+        R0 = SYSCFG_SNEN | SYSCFG_CCEN;
+#endif
         SYSCFG = R0;
         R0 = 0;