[PATCH v3 15/18] ARC: [plat-eznps] Use dedicated identity auxiliary register.

From: Noam Camus
Date: Tue Dec 01 2015 - 08:09:38 EST


From: Noam Camus <noamc@xxxxxxxxxx>

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@xxxxxxxxxx>
---
arch/arc/include/asm/entry-compact.h | 8 ++++++++
arch/arc/kernel/ctx_sw.c | 13 +++++++++++++
2 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/arch/arc/include/asm/entry-compact.h b/arch/arc/include/asm/entry-compact.h
index 1aff3be..bf9a6a1 100644
--- a/arch/arc/include/asm/entry-compact.h
+++ b/arch/arc/include/asm/entry-compact.h
@@ -35,6 +35,7 @@
#include <asm/asm-offsets.h>
#include <asm/irqflags-compact.h>
#include <asm/thread_info.h> /* For THREAD_SIZE */
+#include <plat/ctop.h>

/*--------------------------------------------------------------
* Switch to Kernel Mode stack if SP points to User Mode stack
@@ -298,9 +299,16 @@

/* Get CPU-ID of this core */
.macro GET_CPU_ID reg
+#ifdef CONFIG_ARC_PLAT_EZNPS
+ lr \reg, [CTOP_AUX_LOGIC_GLOBAL_ID]
+#ifndef CONFIG_EZNPS_MTM_EXT
+ lsr \reg, \reg, 4
+#endif
+#else
lr \reg, [identity]
lsr \reg, \reg, 8
bmsk \reg, \reg, 7
+#endif
.endm

#endif /* __ASM_ARC_ENTRY_COMPACT_H */
diff --git a/arch/arc/kernel/ctx_sw.c b/arch/arc/kernel/ctx_sw.c
index 5d446df..6f4cb0d 100644
--- a/arch/arc/kernel/ctx_sw.c
+++ b/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)

@@ -67,9 +70,16 @@ __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"
);

--
1.7.1

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