[ACPI] Tell the BIOS Linux can handle

Enhanced Speed Step (EST). (Venkatesh Pallipadi)
http://bugzilla.kernel.org/show_bug.cgi?id=2712

arch/i386/kernel/cpu/cpufreq/acpi.c

@@ -286,6 +286,69 @@ acpi_cpufreq_guess_freq (
 	
 }
 
+
+/* 
+ * acpi_processor_cpu_init_pdc_est - let BIOS know about the SMP capabilities
+ * of this driver
+ * @perf: processor-specific acpi_io_data struct
+ * @cpu: CPU being initialized
+ *
+ * To avoid issues with legacy OSes, some BIOSes require to be informed of
+ * the SMP capabilities of OS P-state driver. Here we set the bits in _PDC 
+ * accordingly, for Enhanced Speedstep. Actual call to _PDC is done in
+ * driver/acpi/processor.c
+ */
+static void 
+acpi_processor_cpu_init_pdc_est(
+		struct acpi_processor_performance *perf, 
+		unsigned int cpu,
+		struct acpi_object_list *obj_list
+		)
+{
+	union acpi_object *obj;
+	u32 *buf;
+	struct cpuinfo_x86 *c = cpu_data + cpu;
+	ACPI_FUNCTION_TRACE("acpi_processor_cpu_init_pdc_est");
+
+	if (!cpu_has(c, X86_FEATURE_EST))
+		return_VOID;
+
+	/* Initialize pdc. It will be used later. */
+	if (!obj_list)
+		return_VOID;
+		
+	if (!(obj_list->count && obj_list->pointer))
+		return_VOID;
+
+	obj = obj_list->pointer;
+	if ((obj->buffer.length == 12) && obj->buffer.pointer) {
+		buf = (u32 *)obj->buffer.pointer;
+       		buf[0] = ACPI_PDC_REVISION_ID;
+       		buf[1] = 1;
+       		buf[2] = ACPI_PDC_EST_CAPABILITY_SMP;
+		perf->pdc = obj_list;
+	}
+	return_VOID;
+}
+ 
+
+/* CPU specific PDC initialization */
+static void 
+acpi_processor_cpu_init_pdc(
+		struct acpi_processor_performance *perf, 
+		unsigned int cpu,
+		struct acpi_object_list *obj_list
+		)
+{
+	struct cpuinfo_x86 *c = cpu_data + cpu;
+	ACPI_FUNCTION_TRACE("acpi_processor_cpu_init_pdc");
+	perf->pdc = NULL;
+	if (cpu_has(c, X86_FEATURE_EST))
+		acpi_processor_cpu_init_pdc_est(perf, cpu, obj_list);
+	return_VOID;
+}
+
+
 static int
 acpi_cpufreq_cpu_init (
 	struct cpufreq_policy   *policy)
@@ -295,7 +358,14 @@ acpi_cpufreq_cpu_init (
 	struct cpufreq_acpi_io	*data;
 	unsigned int		result = 0;
 
+	union acpi_object		arg0 = {ACPI_TYPE_BUFFER};
+	u32				arg0_buf[3];
+	struct acpi_object_list 	arg_list = {1, &arg0};
+
 	ACPI_FUNCTION_TRACE("acpi_cpufreq_cpu_init");
+	/* setup arg_list for _PDC settings */
+        arg0.buffer.length = 12;
+        arg0.buffer.pointer = (u8 *) arg0_buf;
 
 	data = kmalloc(sizeof(struct cpufreq_acpi_io), GFP_KERNEL);
 	if (!data)
@@ -304,7 +374,10 @@ acpi_cpufreq_cpu_init (
 
 	acpi_io_data[cpu] = data;
 
+	acpi_processor_cpu_init_pdc(&data->acpi_data, cpu, &arg_list);
 	result = acpi_processor_register_performance(&data->acpi_data, cpu);
+	data->acpi_data.pdc = NULL;
+
 	if (result)
 		goto err_free;
 

drivers/acpi/processor.c

@@ -1049,6 +1049,8 @@ acpi_processor_get_performance_info (
 	if (!pr || !pr->performance || !pr->handle)
 		return_VALUE(-EINVAL);
 
+	acpi_processor_set_pdc(pr);
+
 	status = acpi_get_handle(pr->handle, "_PCT", &handle);
 	if (ACPI_FAILURE(status)) {
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, 
@@ -1056,8 +1058,6 @@ acpi_processor_get_performance_info (
 		return_VALUE(-ENODEV);
 	}
 
-	acpi_processor_set_pdc(pr);
-
 	result = acpi_processor_get_performance_control(pr);
 	if (result)
 		return_VALUE(result);

include/asm-i386/acpi.h

@@ -102,6 +102,12 @@ __acpi_release_global_lock (unsigned int *lock)
         :"0"(n_hi), "1"(n_lo))
 
 
+/*
+ * Refer Intel ACPI _PDC support document for bit definitions
+ */
+#define ACPI_PDC_EST_CAPABILITY_SMP 	0xa
+#define ACPI_PDC_EST_CAPABILITY_MSR	0x1
+
 #ifdef CONFIG_ACPI_BOOT 
 extern int acpi_lapic;
 extern int acpi_ioapic;