Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755583Ab3GQOam (ORCPT ); Wed, 17 Jul 2013 10:30:42 -0400 Received: from mail-qe0-f48.google.com ([209.85.128.48]:60884 "EHLO mail-qe0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755155Ab3GQOaO (ORCPT ); Wed, 17 Jul 2013 10:30:14 -0400 Date: Wed, 17 Jul 2013 10:30:10 -0400 (EDT) From: Nicolas Pitre To: Sudeep.KarkadaNagesha@arm.com cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, cpufreq@vger.kernel.org, linux-pm@vger.kernel.org, devicetree-discuss@lists.ozlabs.org, Lorenzo Pieralisi , Russell King , Greg Kroah-Hartman , Rob Herring , "Rafael J. Wysocki" , Grant Likely , Viresh Kumar Subject: Re: [RFC PATCH v2 01/15] of: add support for retrieving cpu node for a given logical cpu index In-Reply-To: <1374069984-20567-2-git-send-email-Sudeep.KarkadaNagesha@arm.com> Message-ID: References: <1374069984-20567-1-git-send-email-Sudeep.KarkadaNagesha@arm.com> <1374069984-20567-2-git-send-email-Sudeep.KarkadaNagesha@arm.com> User-Agent: Alpine 2.03 (LFD 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5397 Lines: 157 On Wed, 17 Jul 2013, Sudeep.KarkadaNagesha@arm.com wrote: > From: Sudeep KarkadaNagesha > > Currently different drivers requiring to access cpu device node are > parsing the device tree themselves. Since the ordering in the DT need > not match the logical cpu ordering, the parsing logic needs to consider > that. However, this has resulted in lots of code duplication and in some > cases even incorrect logic. > > It's better to consolidate them by adding support for getting cpu > device node for a given logical cpu index in DT core library. However > logical to physical index mapping can be architecture specific. > > This patch adds of_get_cpu_node to retrieve a cpu device node for a > given logical cpu index. The default matching of the physical id to the > logical cpu index can be overridden by architecture specific code. > > It is recommended to use these helper function only in pre-SMP/early > initialisation stages to retrieve CPU device node pointers in logical > ordering. Once the cpu devices are registered, it can be retrieved easily > from cpu device of_node which avoids unnecessary parsing and matching. > > Cc: Rob Herring > Signed-off-by: Sudeep KarkadaNagesha > --- > drivers/of/base.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/of.h | 5 +++++ > 2 files changed, 71 insertions(+) > > diff --git a/drivers/of/base.c b/drivers/of/base.c > index 5c54279..363b8f9 100644 > --- a/drivers/of/base.c > +++ b/drivers/of/base.c > @@ -230,6 +230,72 @@ const void *of_get_property(const struct device_node *np, const char *name, > } > EXPORT_SYMBOL(of_get_property); > > +/* > + * arch_match_cpu_phys_id - Match the given logical CPU and physical id > + * > + * @cpu: logical index of a cpu > + * @phys_id: physical identifier of a cpu > + * > + * CPU logical to physical index mapping is architecure specific. Typo. > + * However this __weak function provides a default match of physical > + * id to logical cpu index. > + * > + * Returns 1 if the physical identifier and the logical index correspond > + * to the same cpu, 0 otherwise. > + */ > +int __weak arch_match_cpu_phys_id(int cpu, u64 phys_id) Please use a bool return type, and use true/false rather than 1/0 in the comment. > +{ > + return (u32)phys_id == cpu; > +} > + > +/** > + * of_get_cpu_node - Get device node associated with the given logical CPU > + * > + * @cpu: CPU number(logical index) for which device node is required > + * > + * The main purpose of this function is to retrieve the device node for the > + * given logical CPU index. It should be used to intialise the of_node in Typo. > + * cpu device. Once of_node in cpu device is populated, all the further > + * references can use that instead. > + * > + * CPU logical to physical index mapping is architecure specific and is built Typo. > + * before booting secondary cores. This function uses arch_match_cpu_phys_id > + * which can be overridden by architecture specific implementation. > + * > + * Returns a node pointer for the logical cpu if found, else NULL. > + */ > +struct device_node *of_get_cpu_node(int cpu) > +{ > + struct device_node *cpun, *cpus; > + const u32 *cell; > + u64 hwid; > + int ac, prop_len; > + > + 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", &prop_len); > + if (WARN(!cell, "%s: missing reg property\n", cpun->full_name)) > + continue; > + > + while (prop_len) { > + hwid = of_read_number(cell, ac); > + prop_len -= ac; > + if (arch_match_cpu_phys_id(cpu, hwid)) > + return cpun; > + } > + } > + > + return NULL; > +} > + > /** Checks if the given "compat" string matches one of the strings in > * the device's "compatible" property > */ > diff --git a/include/linux/of.h b/include/linux/of.h > index 1fd08ca..150b48e 100644 > --- a/include/linux/of.h > +++ b/include/linux/of.h > @@ -266,6 +266,7 @@ extern int of_device_is_available(const struct device_node *device); > extern const void *of_get_property(const struct device_node *node, > const char *name, > int *lenp); > +extern struct device_node *of_get_cpu_node(int cpu); > #define for_each_property_of_node(dn, pp) \ > for (pp = dn->properties; pp != NULL; pp = pp->next) > > @@ -458,6 +459,10 @@ static inline const void *of_get_property(const struct device_node *node, > { > return NULL; > } > +static inline struct device_node *of_get_cpu_node(int cpu) > +{ > + return NULL; > +} > > static inline int of_property_read_u64(const struct device_node *np, > const char *propname, u64 *out_value) > -- > 1.8.1.2 > > > _______________________________________________ > devicetree-discuss mailing list > devicetree-discuss@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/devicetree-discuss > -- 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/