From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751118AbdKHIcK (ORCPT ); Wed, 8 Nov 2017 03:32:10 -0500 Received: from fllnx209.ext.ti.com ([198.47.19.16]:63073 "EHLO fllnx209.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750727AbdKHIcI (ORCPT ); Wed, 8 Nov 2017 03:32:08 -0500 Subject: Re: [PATCH] rtc: omap: Support scratch registers To: Alexandre Belloni CC: Sekhar Nori , , , Linux OMAP List References: <20171031162731.27019-1-alexandre.belloni@free-electrons.com> <600fd106-9f79-0f5a-a2fd-e6b067785c17@ti.com> <4741d4c7-d6f7-ecdb-1eed-1293175f38d9@ti.com> <9a383f74-e049-885b-4705-93968f4c75d4@ti.com> <20171108062738.cml7qaek324rvc4e@piout.net> <775d3cfc-95ca-1dff-d146-64efbdd71e1f@ti.com> <20171108071612.65wrw7mhoip55lia@piout.net> <898f67e7-5d65-9067-f40d-0d80462324d5@ti.com> <20171108082145.kpd3c45x5skce5wd@piout.net> From: Keerthy Message-ID: <79f52c27-1c6a-c4ec-9635-d05eec635661@ti.com> Date: Wed, 8 Nov 2017 14:01:37 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171108082145.kpd3c45x5skce5wd@piout.net> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 08 November 2017 01:51 PM, Alexandre Belloni wrote: > On 08/11/2017 at 13:36:15 +0530, Keerthy wrote: >> >> >> On Wednesday 08 November 2017 12:46 PM, Alexandre Belloni wrote: >>> On 08/11/2017 at 12:38:05 +0530, Keerthy wrote: >>>> >>>> >>>> On Wednesday 08 November 2017 11:57 AM, Alexandre Belloni wrote: >>>>> Hi, >>>>> >>>>> On 08/11/2017 at 11:30:45 +0530, Keerthy wrote: >>>>>>>>> +static int omap_rtc_scratch_read(void *priv, unsigned int offset, void *_val, >>>>>>>>> + size_t bytes) >>>>>>>>> +{ >>>>>>>>> + struct omap_rtc *rtc = priv; >>>>>>>>> + u32 *val = _val; >>>>>>>>> + int i; >>>>>>>>> + >>>>>>>>> + for (i = 0; i < bytes / 4; i++) >>>>>>>>> + val[i] = rtc_readl(rtc, >>>>>>>>> + OMAP_RTC_SCRATCH0_REG + offset + (i * 4)); >>>>>> >>>>>> Can the offset be the Scratch register number instead of bytes offset? >>>>>> More intuitive to me. >>>>>> >>>>>> So that one can request using offset as 0, 1, 2 instead of 0, 4, 8? >>>>>> >>>>> >>>>> Well, the offset is coming from the nvmem core, itself getting it from >>>>> the Linux file API (and it is in bytes). However, you have the guarantee >>>>> that it will be aligned on a word, see: >>>>> http://elixir.free-electrons.com/linux/latest/source/drivers/nvmem/core.c#L88 >>>> >>>> Okay Alexandre. Thanks for clarifying. Looks good to me. >>>> I have tested on AM437X-GP-EVM. >>>> >>> >>> If needed, you can define nvmem cells (and I guess that is what you >>> want): >>> http://elixir.free-electrons.com/linux/latest/source/Documentation/devicetree/bindings/nvmem/nvmem.txt >> >> With this patch we cannot still use nvmem_device_write and >> nvmem_device_read as the nvmem_device is still not registered. >> >> How can a driver write to scratch pad registers? Should we be calling >> nvmem_register in the probe? > > It is not needed, it is registered by rtc_nvmem_register(). Let me go through the chain: rtc_register_device -> __rtc_register_device --> rtc_nvmem_register -> rtc_nvram_register I am seeing that for rtc-omap driver there is rtc_register_device call and i see that rtc_nvmem_register is not getting called. Should we add rtc_register_device in probe of rtc-omap? > > nvmem_device_read/write are working because that is what I'm using to > implement the old sysfs ABI with rtc_nvram_read/write. >