From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Barada Subject: RE: Question on how to best access a chip on init that needs VAUX1 power? Date: Fri, 16 Jan 2009 16:05:02 -0500 Message-ID: <1232139902.347.64.camel@blackhole> References: <1232134287.347.44.camel@blackhole> <13B9B4C6EF24D648824FF11BE8967162036D6A1527@dlee02.ent.ti.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from mail.logicpd.com ([66.162.60.3]:22166 "EHLO smtp.logicpd.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1759726AbZAPVFF (ORCPT ); Fri, 16 Jan 2009 16:05:05 -0500 In-Reply-To: <13B9B4C6EF24D648824FF11BE8967162036D6A1527@dlee02.ent.ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Woodruff, Richard" Cc: linux-omap On Fri, 2009-01-16 at 14:17 -0600, Woodruff, Richard wrote: > Subject: Question on how to best access a chip on init that needs VAUX1 power? > > > > On the OMAP board I have, I want to access production information > > (model, serial number, MAC addresses, etc), and the part requires 3v > > which is powered off of VAUX1. > > > > I need to pull this out at initialization time, but I have to wait until > > the twl4030 driver is running or I get "twl4030: client 3 is not > > initialized" when I try to turn on the power. Looking at the > > twl4030-core.c code, I see its invoked via initcall_subsys(). I'd like > > to have my code invoked before the other devices come up (so I can > > provide a MAC address to the ethernet, etc). I'm trying > > initcall_sysbys_sync() to have my code called after the twl4040 > > initializes, but before the devices come up. > > You can access this info from u-boot with i2c api. For development you want the mac address available at that time anyway. > When you program it into Ethernet chip for many it will stick so kernel will see the right thing. That is if I initialize the ethernet in u-boot. To save on power, I'd like to leave the ethernet alone until the user needs it(and at that point can modprobe the driver). I still need the data to setup wireless in the kernel (its mac address, trim values, etc)... > u-boot also has simple utility to read from mtd which has u-boot environment where you could have stored it away. Ultimately I should just pull the block of data in u-boot, extract what I need for u-boot, and then pass it to the kernel. Outside of creating a specific ATAG for this, what's the best way to pass a block of data from u-boot to the kernel? > Regards, > Richard W. -- Peter Barada