From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dong Aisheng Subject: Re: [PATCH v4 1/7] mfd: add syscon driver based on regmap Date: Mon, 3 Sep 2012 10:31:03 +0800 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-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20120831012626.GA7726@r65073-Latitude-D630> 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: Shawn Guo Cc: Zhao Richard-B20223 , "linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org" , "devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , "s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org" , "broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org" , "kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org" , "lrg-l0cyMroinI0@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "sameo-VuQAYsv1563Yd54FQh9/CA@public.gmane.org" List-Id: devicetree@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);