A20内核编译错误undefined reference to `hwmon_device_register'_三言两语

编译A20内核时出现如下错误

drivers/built-in.o: In function `axp20_init_chip':
/home/linux-sunxi/drivers/power/axp_power/axp20-mfd.h:149: undefined reference to `hwmon_device_register'
drivers/built-in.o: In function `axp_mfd_remove':
/home/linux-sunxi/drivers/power/axp_power/axp-mfd.c:368: undefined reference to `hwmon_device_unregister'
make: *** [.tmp_vmlinux1] Error 1drivers/built-in.o: In functi