ARC: [plat-eznps] Use dedicated identity auxiliary register.

With generic "identity" num of CPUs is limited to 256 (8 bit).
We use our alternative AUX register GLOBAL_ID (12 bit).
Now we can support up to 4096 CPUs.

Signed-off-by: Noam Camus <noamc@ezchip.com>

arch/arc/kernel/ctx_sw.c

@@ -16,6 +16,9 @@
 
 #include <asm/asm-offsets.h>
 #include <linux/sched.h>
+#ifdef CONFIG_ARC_PLAT_EZNPS
+#include <plat/ctop.h>
+#endif
 
 #define KSP_WORD_OFF 	((TASK_THREAD + THREAD_KSP) / 4)
 
@@ -66,10 +69,17 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task)
 		 */
 #ifndef CONFIG_SMP
 		"st  %2, [@_current_task]	\n\t"
+#else
+#ifdef CONFIG_ARC_PLAT_EZNPS
+		"lr   r24, [%4]		\n\t"
+#ifndef CONFIG_EZNPS_MTM_EXT
+		"lsr  r24, r24, 4		\n\t"
+#endif
 #else
 		"lr   r24, [identity]		\n\t"
 		"lsr  r24, r24, 8		\n\t"
 		"bmsk r24, r24, 7		\n\t"
+#endif
 		"add2 r24, @_current_task, r24	\n\t"
 		"st   %2,  [r24]		\n\t"
 #endif
@@ -107,6 +117,9 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task)
 
 		: "=r"(tmp)
 		: "n"(KSP_WORD_OFF), "r"(next), "r"(prev)
+#ifdef CONFIG_ARC_PLAT_EZNPS
+		, "i"(CTOP_AUX_LOGIC_GLOBAL_ID)
+#endif
 		: "blink"
 	);