- Add driver auto probing for x86 features v4

[linux-flexiantxendom0-3.2.10.git] / drivers / acpi / processor_perflib.c

diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 85b3237..0af48a8 100644 (file)
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -240,6 +240,28 @@ void acpi_processor_ppc_exit(void)
        acpi_processor_ppc_status &= ~PPC_REGISTERED;
 }
 
+/*
+ * Do a quick check if the systems looks like it should use ACPI
+ * cpufreq. We look at a _PCT method being available, but don't
+ * do a whole lot of sanity checks.
+ */
+void acpi_processor_load_module(struct acpi_processor *pr)
+{
+       static int requested;
+       acpi_status status = 0;
+       struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+
+       if (!arch_has_acpi_pdc() || requested)
+               return;
+       status = acpi_evaluate_object(pr->handle, "_PCT", NULL, &buffer);
+       if (!ACPI_FAILURE(status)) {
+               printk(KERN_INFO PREFIX "Requesting acpi_cpufreq\n");
+               request_module_nowait("acpi_cpufreq");
+               requested = 1;
+       }
+       kfree(buffer.pointer);
+}
+
 static int acpi_processor_get_performance_control(struct acpi_processor *pr)
 {
        int result = 0;