ARM: EXYNOS: fix the hotplug for Cortex-A15

The sequence of cpu_enter_lowpower() for Cortex-A15 is
different from the sequence for Cortex-A9. This patch
implements cpu_enter_lowpower() for EXYNOS5 SoC which
has Cortex-A15 cores.

Basded on original patch has been submitted by Changhwan Youn

Signed-off-by: Changhwan Youn <chaos.youn@samsung.com>
Signed-off-by: Abhilash Kesavan <a.kesavan@samsung.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
[kgene.kim@samsung.com: use flush_cache_louis() instead of
flush_cache_all() as per Lorenzo and Santosh's suggestion]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

diff --git a/arch/arm/mach-exynos/hotplug.c b/arch/arm/mach-exynos/hotplug.c
index f4d7dd20cdacdb31c2f99ea7b9c05b62e5b0a8ee..c3f825b279473447ebbb06fb0fc4c2ab168b6987 100644 (file)
--- a/arch/arm/mach-exynos/hotplug.c
+++ b/arch/arm/mach-exynos/hotplug.c
@@ -20,10 +20,11 @@
 #include <asm/smp_plat.h>
 
 #include <mach/regs-pmu.h>
+#include <plat/cpu.h>
 
 #include "common.h"
 
-static inline void cpu_enter_lowpower(void)
+static inline void cpu_enter_lowpower_a9(void)
 {
        unsigned int v;
 
@@ -45,6 +46,35 @@ static inline void cpu_enter_lowpower(void)
          : "cc");
 }
 
+static inline void cpu_enter_lowpower_a15(void)
+{
+       unsigned int v;
+
+       asm volatile(
+       "       mrc     p15, 0, %0, c1, c0, 0\n"
+       "       bic     %0, %0, %1\n"
+       "       mcr     p15, 0, %0, c1, c0, 0\n"
+         : "=&r" (v)
+         : "Ir" (CR_C)
+         : "cc");
+
+       flush_cache_louis();
+
+       asm volatile(
+       /*
+       * Turn off coherency
+       */
+       "       mrc     p15, 0, %0, c1, c0, 1\n"
+       "       bic     %0, %0, %1\n"
+       "       mcr     p15, 0, %0, c1, c0, 1\n"
+       : "=&r" (v)
+       : "Ir" (0x40)
+       : "cc");
+
+       isb();
+       dsb();
+}
+
 static inline void cpu_leave_lowpower(void)
 {
        unsigned int v;
@@ -103,11 +133,20 @@ static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
 void __ref exynos_cpu_die(unsigned int cpu)
 {
        int spurious = 0;
+       int primary_part = 0;
 
        /*
-        * we're ready for shutdown now, so do it
+        * we're ready for shutdown now, so do it.
+        * Exynos4 is A9 based while Exynos5 is A15; check the CPU part
+        * number by reading the Main ID register and then perform the
+        * appropriate sequence for entering low power.
         */
-       cpu_enter_lowpower();
+       asm("mrc p15, 0, %0, c0, c0, 0" : "=r"(primary_part) : : "cc");
+       if ((primary_part & 0xfff0) == 0xc0f0)
+               cpu_enter_lowpower_a15();
+       else
+               cpu_enter_lowpower_a9();
+
        platform_do_lowpower(cpu, &spurious);
 
        /*