ACPI: processor: introduce arch_has_acpi_pdc

arch dependent helper function that tells us if we should attempt to
evaluate _PDC on this machine or not.

The x86 implementation assumes that the CPUs in the machine must be
homogeneous, and that you cannot mix CPUs of different vendors.

Cc: Tony Luck <tony.luck@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

arch/ia64/include/asm/acpi.h

@@ -132,6 +132,8 @@ extern int __devinitdata pxm_to_nid_map[MAX_PXM_DOMAINS];
 extern int __initdata nid_to_pxm_map[MAX_NUMNODES];
 #endif
 
+static inline bool arch_has_acpi_pdc(void) { return true; }
+
 #define acpi_unlazy_tlb(x)
 
 #ifdef CONFIG_ACPI_NUMA

arch/x86/include/asm/acpi.h

@@ -142,6 +142,13 @@ static inline unsigned int acpi_processor_cstate_check(unsigned int max_cstate)
 		return max_cstate;
 }
 
+static inline bool arch_has_acpi_pdc(void)
+{
+	struct cpuinfo_x86 *c = &cpu_data(0);
+	return (c->x86_vendor == X86_VENDOR_INTEL ||
+		c->x86_vendor == X86_VENDOR_CENTAUR);
+}
+
 #else /* !CONFIG_ACPI */
 
 #define acpi_lapic 0

arch/x86/kernel/acpi/processor.c

@@ -79,8 +79,6 @@ void arch_acpi_processor_init_pdc(struct acpi_processor *pr)
 	struct cpuinfo_x86 *c = &cpu_data(pr->id);
 
 	pr->pdc = NULL;
-	if (c->x86_vendor == X86_VENDOR_INTEL ||
-	    c->x86_vendor == X86_VENDOR_CENTAUR)
 	init_intel_pdc(pr, c);
 
 	return;

drivers/acpi/processor_pdc.c

@@ -69,6 +69,9 @@ static int acpi_processor_eval_pdc(struct acpi_processor *pr)
 
 void acpi_processor_set_pdc(struct acpi_processor *pr)
 {
+	if (arch_has_acpi_pdc() == false)
+		return;
+
 	arch_acpi_processor_init_pdc(pr);
 	acpi_processor_eval_pdc(pr);
 	arch_acpi_processor_cleanup_pdc(pr);