From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: [PATCH] cpuidle: kirkwood: Move out of mach directory, add DT. Date: Fri, 28 Dec 2012 08:55:31 -0600 Message-ID: <50DDB2E3.103@gmail.com> References: <1356698844-4220-1-git-send-email-andrew@lunn.ch> <50DDAA42.2020101@gmail.com> <20121228143517.GA5172@lunn.ch> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20121228143517.GA5172-g2DYL2Zd6BY@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Andrew Lunn Cc: len.brown-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, rafael.j.wysocki-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, Jason Cooper , linux ARM List-Id: devicetree@vger.kernel.org On 12/28/2012 08:35 AM, Andrew Lunn wrote: > On Fri, Dec 28, 2012 at 08:18:42AM -0600, Rob Herring wrote: >> On 12/28/2012 06:47 AM, Andrew Lunn wrote: >>> Move the Kirkwood cpuidle driver out of arch/arm/mach-kirkwood and >>> into drivers/cpuidle. Convert the driver into a platform driver and >>> add a device tree binding. Add a DT node to instantiate the driver for >>> boards converted to DT, and a platform data for old style boards. >> >> Is this an old comment? I don't see any platform data. > > There is no platform data, since all the driver needs is an address of > the DDR control register. The code to create a platform device entry > is in common.c hunk. So you should say "a platform device for old style boards". >>> + cpuidle@1418 { >>> + compatible = "marvell,kirkwood-cpuidle"; >>> + reg = <0x1418 0x4>; >>> + }; >>> + >> >> This is describing what linux wants, not the hardware. This is a common >> problem with cpuidle drivers in that they use shared registers. I don't >> have a good solution, but this doesn't belong in DTS. > > Do you have a bad solution? Ha! :) I should say I don't have a clear, obvious solution. Don't do a platform driver and just check the machine compatible property which is what I did for highbank. Have the machine code create the platform device. Not *all* platform devices have to be created based on the DTB. Create an MFD driver for the whole block of registers. > I could just hard code the address, since its the same for all > kirkwood SoCs. Also, the register is not being used by any other > code on kirkwood, so its not shared. Then describe it based on the reference manual, but you need to do so assuming you are using all the other registers. I assume there are other registers at say 0x1414 or 0x141c. You have to be careful if you create separate nodes for each register or sub-group of registers. It needs to work no matter what the OS expectation is. Rob