platform: mips: cpu_hwmon: Disable driver on unsupported hardware

commit f4d430db17b4ef4e9c3c352a04b2fe3c93011978 upstream.

cpu_hwmon is unsupported on CPUs without loongson_chiptemp
register and csr.

Cc: stable@vger.kernel.org
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 0818a768c96a10343d08a622906adab54da6e014)
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>

drivers/platform/mips/cpu_hwmon.c

@@ -163,6 +163,9 @@ static int __init loongson_hwmon_init(void)
 		goto fail_hwmon_device_register;
 	}
 
+	if (!csr_temp_enable && !loongson_chiptemp[0])
+		return -ENODEV;
+
 	nr_packages = loongson_sysconf.nr_cpus /
 		loongson_sysconf.cores_per_package;