From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Gamari Subject: [RFC PATCH] GPIO chip select support for McSPI Date: Tue, 21 Dec 2010 12:56:34 -0500 Message-ID: <1292954195-20204-1-git-send-email-bgamari.foss__28446.0686882541$1292954246$gmane$org@gmail.com> References: <1b68c6791001272033q60dd31dbif4de285cd9bac83d@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: beagleboard , linux-omap , David Brownell , Eric Miao , Michael Henn Return-path: In-Reply-To: <1b68c6791001272033q60dd31dbif4de285cd9bac83d-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org As you may recall, about a year ago I wrote wondering whether it was possible to use GPIO lines as chip selects in the McSPI driver. A few of you pointed out that this functionality had been added to other drivers and it should be quite simple to do the same for McSPI. Two semesters then passed without a followup from me. Thankfully, classes are over and I've had some downtime due to sickness, finally freeing up some time to look at this (just in time as we'll soon need this functionality). This morning I looked through the relevant code and put together this patch to add support for GPIO CSs. As was suggested, I modelled this after the approach taken in the s3c24xx-spi driver. Let me know whether this looks sane. It has yet to see hardware, but in principle things look alright (famous last words). Cheers, - Ben P.S. In case people are curious to see an example of usage I have a patch adding support for multiplexed chip selects to support a data acquisition board for the BeagleBoard that I've been working on[1]. I can send these out if people are interested. [1] http://goldnerlab.physics.umass.edu/wiki/BeagleBoardDaq ------------------------------------------------------------------------------ Forrester recently released a report on the Return on Investment (ROI) of Google Apps. They found a 300% ROI, 38%-56% cost savings, and break-even within 7 months. Over 3 million businesses have gone Google with Google Apps: an online email calendar, and document program that's accessible from your browser. Read the Forrester report: http://p.sf.net/sfu/googleapps-sfnew