From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755956Ab2ICCxC (ORCPT ); Sun, 2 Sep 2012 22:53:02 -0400 Received: from co1ehsobe004.messaging.microsoft.com ([216.32.180.187]:12590 "EHLO co1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755799Ab2ICCxA (ORCPT ); Sun, 2 Sep 2012 22:53:00 -0400 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: 1 X-BigFish: VS1(zz98dI1432Izz1202h1082kzzz2dh2a8h668h839h944hd25hf0ah107ah1220h1155h) Date: Mon, 3 Sep 2012 10:31:03 +0800 From: Dong Aisheng To: Shawn Guo CC: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linus.walleij@stericsson.com" , "s.hauer@pengutronix.de" , "kernel@pengutronix.de" , "grant.likely@secretlab.ca" , "rob.herring@calxeda.com" , "sameo@linux.intel.com" , "lrg@ti.com" , "broonie@opensource.wolfsonmicro.com" , Zhao Richard-B20223 , "devicetree-discuss@lists.ozlabs.org" , "swarren@wwwdotorg.org" Subject: Re: [PATCH v4 1/7] mfd: add syscon driver based on regmap Message-ID: <20120903023102.GA11891@shlinux2.ap.freescale.net> References: <1346237818-9498-1-git-send-email-b29396@freescale.com> <1346237818-9498-2-git-send-email-b29396@freescale.com> <20120831012626.GA7726@r65073-Latitude-D630> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20120831012626.GA7726@r65073-Latitude-D630> User-Agent: Mutt/1.5.20 (2009-06-14) X-OriginatorOrg: freescale.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 31, 2012 at 09:26:29AM +0800, Shawn Guo wrote: > On Wed, Aug 29, 2012 at 06:56:52PM +0800, Dong Aisheng wrote: > > +config MFD_SYSCON > > + bool "System Controller Register R/W Based on Regmap" > > If the driver only compiles and works for device tree probe, we should > have the following? > > depends on OF > Correct. For currently it only supports dt. > > + select REGMAP_MMIO > > + help > > + Select this option to enable accessing system control registers > > + via regmap. > > + > > > > > +struct regmap *syscon_node_to_regmap(struct device_node *np) > > +{ > > + struct syscon *syscon; > > + struct device *dev; > > + > > + dev = driver_find_device(&syscon_driver.driver, NULL, np, > > + syscon_match); > > + of_node_put(np); > > This looks a little unnatural to me. Function syscon_node_to_regmap > becomes an API visible to clients, who might never know that np will > be put inside the API. I'm saying the client may also call of_node_put > to put the node they get. We probably could add a comment here for the API to avoid this happen. > > I think of_node_put should be moved out from here and put into > syscon_node_to_regmap and syscon_regmap_lookup_by_compatible. > I guess no, if you want to move of_node_put into syscon_regmap_lookup_by_phandle, then syscon_regmap_lookup_by_phandle has the same issue. Actually i had considered your concern when writing this API... The original purpose of doing like that is saving some duplicated 'of_node_put' and make the API easy to use. I searched the kernel dt code and found it existed some similar cases. e.g: of_irq_find_parent, of_get_next_parent So it looks to me that it may be usually to do like that for the cases that the conversion from a node to other thing since the client may only care about the things converted. For our case, it's regmap. So i can't think it make too much sense for all client driver have to write duplicated and meaningless 'of_node_put' code. Regards Dong Aisheng > > + > > + if (!dev) > > + return ERR_PTR(-EPROBE_DEFER); > > + > > + syscon = dev_get_drvdata(dev); > > + > > + return syscon->regmap; > > +} > > +EXPORT_SYMBOL_GPL(syscon_node_to_regmap); > > + > > +struct regmap *syscon_regmap_lookup_by_compatible(const char *s) > > +{ > > + struct device_node *syscon_np; > > + > > + syscon_np = of_find_compatible_node(NULL, NULL, s); > > + if (!syscon_np) > > + return ERR_PTR(-ENODEV); > > + > > + return syscon_node_to_regmap(syscon_np); > > +} > > +EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible); > > + > > +struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np, > > + const char *property) > > +{ > > + struct device_node *syscon_np; > > + > > + syscon_np = of_parse_phandle(np, property, 0); > > + if (!syscon_np) > > + return ERR_PTR(-ENODEV); > > + > > + return syscon_node_to_regmap(syscon_np); > > +} > > +EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);