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authorNoam Camus <noamca@mellanox.com>2017-05-28 09:52:06 +0300
committerVineet Gupta <vgupta@synopsys.com>2017-08-29 01:17:36 +0300
commit644fa02b392e25d7592951da2b2b64b4d533d1be (patch)
tree478eb451af152ed2ea0349f8c217602af9405523 /arch/arc
parent64f42cec84deb32fdaf24649481c72fcd7800dc1 (diff)
downloadlinux-644fa02b392e25d7592951da2b2b64b4d533d1be.tar.xz
ARC: [plat-eznps] use schd.wft instruction instead of sleep at idle task
When HW threads are active we want CPU to enter idle state only for the calling HW thread and not to put on sleep all HW threads sharing this core. For this need the NPS400 got dedicated instruction so only calling thread is entring sleep and all other are still awake and can execute instructions. Signed-off-by: Noam Camus <noamca@mellanox.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> [vgupta: reworked patch to not use inline ifdef but a new function itself]
Diffstat (limited to 'arch/arc')
-rw-r--r--arch/arc/kernel/process.c13
-rw-r--r--arch/arc/plat-eznps/include/plat/ctop.h1
2 files changed, 13 insertions, 1 deletions
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c
index fd5b2190a957..5c631a111240 100644
--- a/arch/arc/kernel/process.c
+++ b/arch/arc/kernel/process.c
@@ -92,7 +92,18 @@ void arch_cpu_idle(void)
:"I"(arg)); /* can't be "r" has to be embedded const */
}
-#else
+#elif defined(CONFIG_EZNPS_MTM_EXT) /* ARC700 variant in NPS */
+
+void arch_cpu_idle(void)
+{
+ /* only the calling HW thread needs to sleep */
+ __asm__ __volatile__(
+ ".word %0 \n"
+ :
+ :"i"(CTOP_INST_HWSCHD_WFT_IE12));
+}
+
+#else /* ARC700 */
void arch_cpu_idle(void)
{
diff --git a/arch/arc/plat-eznps/include/plat/ctop.h b/arch/arc/plat-eznps/include/plat/ctop.h
index ee2e32df5e90..7729d3d18300 100644
--- a/arch/arc/plat-eznps/include/plat/ctop.h
+++ b/arch/arc/plat-eznps/include/plat/ctop.h
@@ -46,6 +46,7 @@
#define CTOP_AUX_UDMC (CTOP_AUX_BASE + 0x300)
/* EZchip core instructions */
+#define CTOP_INST_HWSCHD_WFT_IE12 0x3E6F7344
#define CTOP_INST_HWSCHD_OFF_R4 0x3C6F00BF
#define CTOP_INST_HWSCHD_RESTORE_R4 0x3E6F7103
#define CTOP_INST_SCHD_RW 0x3E6F7004