ARM: 8130/1: cpuidle/cpuidle-big_little: fix reading cpu id part number

Commit af040ffc9ba1 ("ARM: make it easier to check the CPU part number
correctly") changed ARM_CPU_PART_X masks, and the way they are returned and
checked against. Usage of read_cpuid_part_number() is now deprecated, and
calling places updated accordingly. This actually broke cpuidle-big_little
initialization, as bl_idle_driver_init() performs a check using an hardcoded
mask on cpu_id.

Create an interface to perform the check (that is now even easier to read).
Define also a proper mask (ARM_CPU_PART_MASK) that makes this kind of checks
cleaner and helps preventing bugs in the future. Update usage accordingly.

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 20 insertions, 11 deletions

diff --git a/arch/arm/include/asm/cputype.h b/arch/arm/include/asm/cputype.h
index 963a2515906d..819777d0e91f 100644
--- a/arch/arm/include/asm/cputype.h
+++ b/arch/arm/include/asm/cputype.h
@@ -74,6 +74,7 @@
 #define ARM_CPU_PART_CORTEX_A12         0x4100c0d0
 #define ARM_CPU_PART_CORTEX_A17         0x4100c0e0
 #define ARM_CPU_PART_CORTEX_A15         0x4100c0f0
+#define ARM_CPU_PART_MASK               0xff00fff0
 
 #define ARM_CPU_XSCALE_ARCH_MASK        0xe000
 #define ARM_CPU_XSCALE_ARCH_V1          0x2000
@@ -179,7 +180,7 @@ static inline unsigned int __attribute_const__ read_cpuid_implementor(void)
  */
 static inline unsigned int __attribute_const__ read_cpuid_part(void)
 {
-        return read_cpuid_id() & 0xff00fff0;
+        return read_cpuid_id() & ARM_CPU_PART_MASK;
 }
 
 static inline unsigned int __attribute_const__ __deprecated read_cpuid_part_number(void)
diff --git a/arch/arm/include/asm/smp_plat.h b/arch/arm/include/asm/smp_plat.h
index a252c0bfacf5..0ad7d490ee6f 100644
--- a/arch/arm/include/asm/smp_plat.h
+++ b/arch/arm/include/asm/smp_plat.h
@@ -8,6 +8,7 @@
 #include <linux/cpumask.h>
 #include <linux/err.h>
 
+#include <asm/cpu.h>
 #include <asm/cputype.h>
 
 /*
@@ -25,6 +26,20 @@ static inline bool is_smp(void)
 #endif
 }
 
+/**
+ * smp_cpuid_part() - return part id for a given cpu
+ * @cpu:        logical cpu id.
+ *
+ * Return: part id of logical cpu passed as argument.
+ */
+static inline unsigned int smp_cpuid_part(int cpu)
+{
+        struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpu);
+
+        return is_smp() ? cpu_info->cpuid & ARM_CPU_PART_MASK :
+                          read_cpuid_part();
+}
+
 /* all SMP configurations have the extended CPUID registers */
 #ifndef CONFIG_MMU
 #define tlb_ops_need_broadcast()        0
diff --git a/drivers/cpuidle/cpuidle-big_little.c b/drivers/cpuidle/cpuidle-big_little.c
index 344d79fa3407..ef94c3b81f18 100644
--- a/drivers/cpuidle/cpuidle-big_little.c
+++ b/drivers/cpuidle/cpuidle-big_little.c
@@ -138,25 +138,18 @@ static int bl_enter_powerdown(struct cpuidle_device *dev,
         return idx;
 }
 
-static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int cpu_id)
+static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id)
 {
-        struct cpuinfo_arm *cpu_info;
         struct cpumask *cpumask;
-        unsigned long cpuid;
         int cpu;
 
         cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
         if (!cpumask)
                 return -ENOMEM;
 
-        for_each_possible_cpu(cpu) {
-                cpu_info = &per_cpu(cpu_data, cpu);
-                cpuid = is_smp() ? cpu_info->cpuid : read_cpuid_id();
-
-                /* read cpu id part number */
-                if ((cpuid & 0xFFF0) == cpu_id)
+        for_each_possible_cpu(cpu)
+                if (smp_cpuid_part(cpu) == part_id)
                         cpumask_set_cpu(cpu, cpumask);
-        }
 
         drv->cpumask = cpumask;