|  | Kernel driver raspberrypi-hwmon | 
|  | =============================== | 
|  |  | 
|  | Supported boards: | 
|  |  | 
|  | * Raspberry Pi A+ (via GPIO on SoC) | 
|  | * Raspberry Pi B+ (via GPIO on SoC) | 
|  | * Raspberry Pi 2 B (via GPIO on SoC) | 
|  | * Raspberry Pi 3 B (via GPIO on port expander) | 
|  | * Raspberry Pi 3 B+ (via PMIC) | 
|  |  | 
|  | Author: Stefan Wahren <stefan.wahren@i2se.com> | 
|  |  | 
|  | Description | 
|  | ----------- | 
|  |  | 
|  | This driver periodically polls a mailbox property of the VC4 firmware to detect | 
|  | undervoltage conditions. | 
|  |  | 
|  | Sysfs entries | 
|  | ------------- | 
|  |  | 
|  | ======================= ================== | 
|  | in0_lcrit_alarm		Undervoltage alarm | 
|  | ======================= ================== |