Recent Raspberry Pi firmware provides a mailbox property to detect
under-voltage conditions. Here is the current definition.
The u32 value returned by the firmware is divided into 2 parts:
- lower 16-bits are the live value
- upper 16-bits are the history or sticky value
Bits:
0: undervoltage
1: arm frequency capped
2: currently throttled
16: undervoltage has occurred
17: arm frequency capped has occurred
18: throttling has occurred
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
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