ACPI: Set max_cstate to 1 for early Opterons.

AMD Opteron processors before CG revision don't like C-states > 1.

This solves the long standing bugzilla #5303 and probably some more
on affected machines:

  http://bugzilla.kernel.org/show_bug.cgi?id=5303

[ tglx@linutronix.de: reworked the patch so it does not wreck ia64 ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

drivers/acpi/processor_idle.c

@@ -1658,6 +1658,7 @@ int __cpuinit acpi_processor_power_init(struct acpi_processor *pr,
 
 	if (!first_run) {
 		dmi_check_system(processor_power_dmi_table);
+		max_cstate = acpi_processor_cstate_check(max_cstate);
 		if (max_cstate < ACPI_C_STATES_MAX)
 			printk(KERN_NOTICE
 			       "ACPI: processor limited to max C-state %d\n",

include/asm-ia64/acpi.h

@@ -94,6 +94,7 @@ ia64_acpi_release_global_lock (unsigned int *lock)
 #define acpi_noirq 0	/* ACPI always enabled on IA64 */
 #define acpi_pci_disabled 0 /* ACPI PCI always enabled on IA64 */
 #define acpi_strict 1	/* no ACPI spec workarounds on IA64 */
+#define acpi_processor_cstate_check(x) (x) /* no idle limits on IA64 :) */
 static inline void disable_acpi(void) { }
 
 const char *acpi_get_sysname (void);

include/asm-x86/acpi.h

+#ifndef _ASM_X86_ACPI_H
+#define _ASM_X86_ACPI_H
+
 #ifdef CONFIG_X86_32
 # include "acpi_32.h"
 #else
 # include "acpi_64.h"
 #endif
+
+#include <asm/processor.h>
+
+/*
+ * Check if the CPU can handle C2 and deeper
+ */
+static inline unsigned int acpi_processor_cstate_check(unsigned int max_cstate)
+{
+	/*
+	 * Early models (<=5) of AMD Opterons are not supposed to go into
+	 * C2 state.
+	 *
+	 * Steppings 0x0A and later are good
+	 */
+	if (boot_cpu_data.x86 == 0x0F &&
+	    boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
+	    boot_cpu_data.x86_model <= 0x05 &&
+	    boot_cpu_data.x86_mask < 0x0A)
+		return 1;
+	else
+		return max_cstate;
+}
+
+#endif