Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753229Ab2KTWcz (ORCPT ); Tue, 20 Nov 2012 17:32:55 -0500 Received: from mail-pa0-f46.google.com ([209.85.220.46]:34683 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752489Ab2KTWcy (ORCPT ); Tue, 20 Nov 2012 17:32:54 -0500 MIME-Version: 1.0 In-Reply-To: References: From: Grant Likely Date: Tue, 20 Nov 2012 22:32:33 +0000 X-Google-Sender-Auth: vJsjJ5vl5tA0zyUELwkV_54Yziw Message-ID: Subject: Re: Device tree node to major/minor? To: Simon Glass Cc: lk , Devicetree Discuss , Che-liang Chiou Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1251 Lines: 29 On Tue, Nov 20, 2012 at 10:23 PM, Simon Glass wrote: > Hi, > > I hope this is a stupid question with an easy answer, but I cannot find it. > > I have a device tree node for an mmc block device and I want to use > that block device from another driver. I have a phandle which lets me > get the node of the mmc device, but I am not sure how to convert that > into a block_device. In order to do so, I think I need a major/minor > number. Of course the phandle might in fact point to a SCSI driver and > I want that to work correctly also. > > I imagine I might be able to search through the wonders of sysfs in > user space, but is there a better way? Do you /want/ to do it from userspace? What is your use case? Mounting the rootfs? Regardless, userspace can monitor the uevents when devices are added (that's what udev does) and watch for the full path of the node you want in the uevent attribute. Then you can look for the child device with the block major/minor numbers in it. g. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/