Add RTC device file

[vinc]

• Add a device file for the RTC at /dev/rtc
• Allow writing to the device to change the date and time

[vinc]

> read /dev/rtc
2022-08-28 09:23:21

> lisp
MOROS Lisp v0.3.0

> (load "/lib/lisp/core.lsp")
true

> (read-file "/dev/rtc")
"2022-08-28 09:24:47"

[vinc]

Some RTC have a century register at 0x32 but it could be at another port defined in an ACPI table. It can also be absent, or worse, wrong. I experimented with it but had issues with dates in future centuries.

For now dates should be between the beginning of 2000 and the end of 2099:

> print "2099-12-31 23:59:57" => /dev/rtc

> date
2099-12-31 23:59:58 +0000

> date
2099-12-31 23:59:59 +0000

> date
2000-01-01 00:00:00 +0000

Hopefully we'll have a better system by the end of the century :)