ARM: msm: platsmp: determine number of CPU cores at boot time

Previously we just assumed there were CONFIG_NR_CPUS cpus present in
the system. Instead, figure out the number of cpus from the MIDR
register.

Signed-off-by: Jeff Ohlstein <johlstei@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>
[arnd: clarified patch title]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 9 insertions, 2 deletions

diff --git a/arch/arm/mach-msm/platsmp.c b/arch/arm/mach-msm/platsmp.c
index 2034098cf015..5ba77d00361c 100644
--- a/arch/arm/mach-msm/platsmp.c
+++ b/arch/arm/mach-msm/platsmp.c
@@ -18,6 +18,7 @@
 
 #include <asm/hardware/gic.h>
 #include <asm/cacheflush.h>
+#include <asm/cputype.h>
 #include <asm/mach-types.h>
 
 #include <mach/msm_iomap.h>
@@ -40,6 +41,12 @@ volatile int pen_release = -1;
 
 static DEFINE_SPINLOCK(boot_lock);
 
+static inline int get_core_count(void)
+{
+        /* 1 + the PART[1:0] field of MIDR */
+        return ((read_cpuid_id() >> 4) & 3) + 1;
+}
+
 void __cpuinit platform_secondary_init(unsigned int cpu)
 {
         /* Configure edge-triggered PPIs */
@@ -147,9 +154,9 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
  */
 void __init smp_init_cpus(void)
 {
-        unsigned int i;
+        unsigned int i, ncores = get_core_count();
 
-        for (i = 0; i < NR_CPUS; i++)
+        for (i = 0; i < ncores; i++)
                 set_cpu_possible(i, true);
 
         set_smp_cross_call(gic_raise_softirq);