From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 28 May 2002 10:44:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 28 May 2002 10:44:45 -0400 Received: from pc2-cwma1-5-cust12.swa.cable.ntl.com ([80.5.121.12]:48378 "EHLO irongate.swansea.linux.org.uk") by vger.kernel.org with ESMTP id ; Tue, 28 May 2002 10:44:44 -0400 Subject: Re: Changing the current RTC device interface From: Alan Cox To: Abraham vd Merwe Cc: Linux Kernel Development In-Reply-To: <20020528162435.A4917@crystal.2d3d.co.za> Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Ximian Evolution 1.0.3 (1.0.3-6) Date: 28 May 2002 16:46:35 +0100 Message-Id: <1022600795.4123.91.camel@irongate.swansea.linux.org.uk> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2002-05-28 at 15:24, Abraham vd Merwe wrote: > 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. I think you should wait until 2.5 has reached the point we have a finished devicefs and 32bit dev_t. Basically we don't have enough device numbering left for such trivialities right now.