NAME
nvram —
Mostek MK48T0x battery-backed realtime
clock
SYNOPSIS
nvram0 at pcctwo0 offset 0xc0000 (MVME1x7)
nvram0 at syscon0 offset 0x80000 (MVME188)
DESCRIPTION
The nvram driver provides support for the
Mostek MK48T02 (on MVME188) or MK48T08 (on MVME1x7) realtime clocks
chips.
In addition to the clock itself, these chips embed 2KB (MK48T02) or 8KB (MK48T08) of battery-backed memory, which is accessible through the special /dev/nvram0 file.
FILES
- /dev/nvram0
SEE ALSO
CAVEATS
The last 8 bytes of the battery-backed memory contains the realtime clock registers. Writing to these locations will interfere with proper clock operation.
The second half of the battery-backed memory (including the clock
registers) is reserved by Motorola for use by the BUG firmware to store its
configuration data. The nvram driver does not
prevent access to this reserved part.