Changing the current RTC device interface

Abraham vd Merwe (abraham@2d3d.co.za)
Tue, 28 May 2002 16:24:35 +0200


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Hi!

I have a board with multiple RTC chips (Built-in RTC in the processor +
external battery backed RTC).

There are pros and cons to each RTC chip. The CPU's RTC doesn't have a
battery, but have high resolution timing + multiple rtc counters/interrupts,
so it is especially suited for apps that want to use /dev/rtc for high
resolution timing.

On the other hand the external RTC chip can keep time, but its timing is
crap (1hz to 8khz in steps of powers of two), so you don't want to use that
for timing.

At the moment, Linux only allows for a single RTC device, so one can't reap
the benefits of both chips mentioned above.

How about we get a major number assigned to rtc subsystem and then allows
for multiple rtc devices.

The same argument goes for the non-volatile ram found on RTC chips, so we
actually need to change the entire RTC interface so that we can throw away
/dev/nvram

Any objections / suggestions / comments about things that's wrong/right
about the current RTC implementation?

--=20

Regards
Abraham

Never leave anything to chance; make sure all your crimes are premeditated.

__________________________________________________________
Abraham vd Merwe - 2d3D, Inc.

Device Driver Development, Outsourcing, Embedded Systems

Cell: +27 82 565 4451 Snailmail:
Tel: +27 21 761 7549 Block C, Aintree Park
Fax: +27 21 761 7648 Doncaster Road
Email: abraham@2d3d.co.za Kenilworth, 7700
Http: http://www.2d3d.com South Africa

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