From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,T_DKIMWL_WL_HIGH,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 59B82C433EF for ; Wed, 13 Jun 2018 15:00:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0EA95208AF for ; Wed, 13 Jun 2018 15:00:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="q2eB4Rc1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0EA95208AF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935939AbeFMPAk (ORCPT ); Wed, 13 Jun 2018 11:00:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:49422 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935734AbeFMPAi (ORCPT ); Wed, 13 Jun 2018 11:00:38 -0400 Received: from mail-it0-f43.google.com (mail-it0-f43.google.com [209.85.214.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 35294208AF; Wed, 13 Jun 2018 15:00:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1528902038; bh=Ar9qFdvZ18Y7P9v6lgRMmV2DaywiLhTiyRmVQuMCazA=; h=In-Reply-To:References:From:Date:Subject:To:Cc:From; b=q2eB4Rc14sdqTGg2lkr3Y7tFtCMjA6OhP9phPwT//mLHfddwYLCkdPQpMYRtvda3E gyDQTVB8hyPdtoj7Q7Tdk5F+OvWXy2jnzDcGqXJPAOj4Wk9SRFUFmhi3vpoGQjuNBs 7roXJC2ge3CAp28T7H1lWokJkR2SEMXwzl7dPa9I= Received: by mail-it0-f43.google.com with SMTP id p185-v6so4276300itp.4; Wed, 13 Jun 2018 08:00:38 -0700 (PDT) X-Gm-Message-State: APt69E20Pee9/RP3jXty1/X2sLwYTBeOvddCSHL3QLxrrbusUGkORo1p TTYJz7zmx+V/p1PwByu+FplYoNBOLlqFCcm/ew== X-Google-Smtp-Source: ADUXVKLdllfERofpdelI4P35eSJUBsRo6teb+BxUZJwDXWc9cF1bEFGtG9jw5WHEkj+3efnoEAGjBLpvDcxgcShnqYs= X-Received: by 2002:a24:798f:: with SMTP id z137-v6mr4728554itc.19.1528902037645; Wed, 13 Jun 2018 08:00:37 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a4f:6403:0:0:0:0:0 with HTTP; Wed, 13 Jun 2018 08:00:17 -0700 (PDT) In-Reply-To: References: <23be2945b593a36d8fa1970bb579389c0f892a3e.camel@kernel.crashing.org> From: Rob Herring Date: Wed, 13 Jun 2018 09:00:17 -0600 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] drivers/of: Add devm_of_iomap() To: Benjamin Herrenschmidt Cc: devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 12, 2018 at 4:53 PM, Benjamin Herrenschmidt wrote: > On Tue, 2018-06-12 at 11:42 -0600, Rob Herring wrote: >> On Mon, Jun 11, 2018 at 6:01 PM, Benjamin Herrenschmidt >> wrote: >> > There are still quite a few cases where a device might want to get to a >> > different node of the device-tree, obtain the resources and map them. >> > >> > Drivers doing that currently open code the whole thing, which is error >> > proe. >> > >> > We have of_iomap() and of_io_request_and_map() but they both have shortcomings, >> > such as not returning the size of the resource found (which can be necessary) >> > and not being "managed". >> > >> > This adds a devm_of_iomap() that provides all of these and should probably >> > replace uses of the above in most drivers. >> > >> > Signed-off-by: Benjamin Herrenschmidt >> > --- >> > >> > I'm cooking a driver that uses this, if there's no objection I'd like >> > to carry it in my pull request for that driver (it can also exist in >> > the DT tree of course). Just let me know. >> >> We generally only use of_iomap when there is no struct device for any >> new driver. Why can't you use devm_ioremap_resource? Is this a >> non-platform bus device? > > This is just a wrapper on devm_ioremap_resource :-) Basically it's a > "fixed" version of of_iomap, that has the devm* management and will > mark the resource busy. > > My thinking was to then replace most of_iomap users with this. > > As for the specific case of the driver I'm cooking, it's a case where > the SoC contains a little coprocessor (a ColdFire even !) alongside the Wow. Must be the 1 licensee. > main ARM core. I have a driver that offloads the bitbanging of some > GPIOs to it (to implement the FSI bus). I use devm_of_iomap() to map > the registers of the interrupt controller of the coprocessor, it's not > really part of the interrupt tree, it doesn't distribute interrupts to > the ARM or to Linux, it's just a device-node pointed to by a handle. Accessing another processor's interrupt controller. What could go wrong with that. I guess this is fine. There's another problem though. This doesn't work on Sparc because address.c is not built. I'd suggest moving to of/device.c or a new file. > BTW. Another thing that I find a bit annoying is "allocated" reserved- > memory, there's no API to get to it other than via the DMA APIs or a > CMA, which is overkill in a few circumstances (such as the one here > where I just want to dedicate a bit of memory to the coprocessor). > Right now I'm using a fixed reservation (with a reg property) and go to > it "manually" but that somewhat sucks. But that's not really a DT problem. It's a kernel problem if you can't reserve a contiguous range of unmapped pages. But why not just get coherent allocation and ignore that it is mapped. That seems better to me than working around it in DT. Rob