ACPI: thermal: create "thermal.off=1" to disable ACPI thermal support

"thermal.off=1" disables all ACPI thermal support at boot time.

CONFIG_ACPI_THERMAL=n can do this at build time.
"# rmmod thermal" can do this at run time,
as long as thermal is built as a module.

WARNING: On some systems, disabling ACPI thermal support
will cause the system to run hotter and reduce the
lifetime of the hardware.
Signed-off-by: NLen Brown <len.brown@intel.com>

Documentation/kernel-parameters.txt

@@ -1820,6 +1820,9 @@ and is between 256 and 4096 characters. It is defined in the file
 	thash_entries=	[KNL,NET]
 			Set number of hash buckets for TCP connection
 
+	thermal.off=	[HW,ACPI]
+			1: disable ACPI thermal control
+
 	time		Show timing data prefixed to each printk message line
 			[deprecated, see 'printk.time']
 

drivers/acpi/thermal.c

@@ -78,6 +78,10 @@ static int tzp;
 module_param(tzp, int, 0);
 MODULE_PARM_DESC(tzp, "Thermal zone polling frequency, in 1/10 seconds.\n");
 
+static int off;
+module_param(off, int, 0);
+MODULE_PARM_DESC(off, "Set to disable ACPI thermal support.\n");
+
 static int acpi_thermal_add(struct acpi_device *device);
 static int acpi_thermal_remove(struct acpi_device *device, int type);
 static int acpi_thermal_resume(struct acpi_device *device);
@@ -1285,7 +1289,10 @@ static int __init acpi_thermal_init(void)
 {
 	int result = 0;
 
-
+	if (off) {
+		printk(KERN_NOTICE "ACPI: thermal control disabled\n");
+		return -ENODEV;
+	}
 	acpi_thermal_dir = proc_mkdir(ACPI_THERMAL_CLASS, acpi_root_dir);
 	if (!acpi_thermal_dir)
 		return -ENODEV;