Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755523Ab3GQOQ6 (ORCPT ); Wed, 17 Jul 2013 10:16:58 -0400 Received: from service87.mimecast.com ([91.220.42.44]:58735 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755407Ab3GQOQ4 convert rfc822-to-8bit (ORCPT ); Wed, 17 Jul 2013 10:16:56 -0400 Message-ID: <51E6A756.1000300@arm.com> Date: Wed, 17 Jul 2013 15:16:54 +0100 From: Sudeep KarkadaNagesha User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130623 Thunderbird/17.0.7 MIME-Version: 1.0 To: Rob Herring CC: Sudeep KarkadaNagesha , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Lorenzo Pieralisi , "linux@arm.linux.org.uk" , "arnd@arndb.de" , "viresh.kumar@linaro.org" , "rob.herring@calxeda.com" , "rjw@sisk.pl" , "grant.likely@linaro.org" , "cpufreq@vger.kernel.org" , "kernel@pengutronix.de" , "gregkh@linuxfoundation.org" , "olof@lixom.net" , "gregory.clement@free-electrons.com" , "shawn.guo@linaro.org" Subject: Re: [RFC PATCH 02/11] ARM: DT/kernel: define ARM specific arch_of_get_cpu_node References: <1373883732-26303-1-git-send-email-Sudeep.KarkadaNagesha@arm.com> <1373883732-26303-3-git-send-email-Sudeep.KarkadaNagesha@arm.com> <51E44943.7000600@gmail.com> <51E50C59.50900@arm.com> In-Reply-To: <51E50C59.50900@arm.com> X-OriginalArrivalTime: 17 Jul 2013 14:16:50.0938 (UTC) FILETIME=[47DB55A0:01CE82F8] X-MC-Unique: 113071715165400901 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2929 Lines: 73 On 16/07/13 10:03, Sudeep KarkadaNagesha wrote: > On 15/07/13 20:10, Rob Herring wrote: >> On 07/15/2013 05:22 AM, Sudeep.KarkadaNagesha@arm.com wrote: >>> From: Sudeep KarkadaNagesha >>> >>> CPU subsystem now provides architecture specific hook to retrieve the >>> of_node. Most of the cpu DT node parsing and initialisation is contained >>> in devtree.c. It's better to contain all CPU device node parsing there. >>> >>> arch_of_get_cpu_node is mainly used to assign cpu->of_node when CPUs get >>> registered. This patch overrides the defination of the same. It can also >>> act as the helper function in pre-SMP/early initialisation stages to >>> retrieve CPU device node pointers in logical ordering. >>> >>> This mainly helps to avoid replication of the code doing CPU node parsing >>> and physical(MPIDR) to logical mapping. >>> >>> Signed-off-by: Sudeep KarkadaNagesha >> >> [snip] >> >>> +struct device_node * __init arch_of_get_cpu_node(int cpu) >>> +{ >>> + struct device_node *cpun, *cpus; >>> + const u32 *cell; >>> + u64 hwid; >>> + int ac; >>> + >>> + cpus = of_find_node_by_path("/cpus"); >>> + if (WARN(!cpus, "Missing cpus node, bailing out\n")) >>> + return NULL; >>> + >>> + if (WARN_ON(of_property_read_u32(cpus, "#address-cells", &ac))) >>> + ac = of_n_addr_cells(cpus); >>> + >>> + for_each_child_of_node(cpus, cpun) { >>> + if (of_node_cmp(cpun->type, "cpu")) >>> + continue; >>> + cell = of_get_property(cpun, "reg", NULL); >>> + if (WARN(!cell, "%s: missing reg property\n", cpun->full_name)) >>> + continue; >>> + >>> + hwid = of_read_number(cell, ac); >>> + if ((hwid & MPIDR_HWID_BITMASK) == cpu_logical_map(cpu)) >> >> Most of this function is not ARM specific, so it would be nice if we >> could shrink the arch specific part down to just this match. A default >> match of reg == logical cpu number might be useful. >> > I completely agree, in fact that was my initial idea too. > > But when I had a look at powerpc implementation of "of_get_cpu_node" in > arch/powerpc/kernel/prom.c, it looked like PPC is using some > compatibles(e.g. ibm,ppc-interrupt-server#s) which are not specified in > ePAPR. I am not sure is that's allowed or not, if allowed then we can't > have generic of_get_cpu_node with just arch specific hwid matching function. I meant property names not compatibles. Looks like PPC and SPARC seem to use non-standard property names like "cpuid", "ibm,ppc-interrupt-server#s" instead of single "reg" property for all cpus/threads Since the cpufreq driver doesn't depend on those properties, I moved arch_of_get_cpu_node to OF/DT core in v2. Regards, Sudeep -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/