From: Francesco Lavra <francescolavra.fl@gmail.com> To: Viresh Kumar <viresh.kumar@linaro.org> Cc: rjw@sisk.pl, nicolas.pitre@linaro.org, robin.randhawa@arm.com, linux@arm.linux.org.uk, mark.hambleton@broadcom.com, linux-pm@vger.kernel.org, Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>, devicetree-discuss@lists.ozlabs.org, Liviu.Dudau@arm.com, linux-kernel@vger.kernel.org, cpufreq@vger.kernel.org, linaro-kernel@lists.linaro.org, Steve.Bannister@arm.com, arvind.chauhan@arm.com, linux-arm-kernel@lists.infradead.org, charles.garcia-tobin@arm.com Subject: Re: [PATCH V2] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue Date: Sat, 13 Apr 2013 22:13:58 +0200 [thread overview] Message-ID: <5169BC86.7010905@gmail.com> (raw) In-Reply-To: <1f864ec505cae7c5daea3810a3c26e0f5cda38ea.1364290815.git.viresh.kumar@linaro.org> On 03/26/2013 10:51 AM, Viresh Kumar wrote: > big LITTLE is ARM's new Architecture focussing power/performance needs of modern > world. More information about big LITTLE can be found here: > > http://www.arm.com/products/processors/technologies/biglittleprocessing.php > http://lwn.net/Articles/481055/ > > In order to keep cpufreq support for all big LITTLE platforms simple/generic, > this patch tries to add a generic cpufreq driver layer for all big LITTLE > platforms. > > The driver is divided into two parts: > - Core driver: Generic and shared across all big LITTLE SoC's > - Glue drivers: Per platform drivers providing ops to the core driver > > This patch adds in a generic glue driver which would extract information from > Device Tree. > > Future SoC's can either reuse the DT glue or write their own depending on the > need. > > Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com> > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> [...] > diff --git a/drivers/cpufreq/arm_big_little_dt.c b/drivers/cpufreq/arm_big_little_dt.c > new file mode 100644 > index 0000000..452ff46 > --- /dev/null > +++ b/drivers/cpufreq/arm_big_little_dt.c > @@ -0,0 +1,92 @@ > +/* > + * Generic big.LITTLE CPUFreq Interface driver > + * > + * It provides necessary ops to arm_big_little cpufreq driver and gets > + * Frequency information from Device Tree. Freq table in DT must be in KHz. > + * > + * Copyright (C) 2013 Linaro. > + * Viresh Kumar <viresh.kumar@linaro.org> > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + * > + * This program is distributed "as is" WITHOUT ANY WARRANTY of any > + * kind, whether express or implied; without even the implied warranty > + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + */ > + > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > + > +#include <linux/cpufreq.h> > +#include <linux/device.h> > +#include <linux/export.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/opp.h> > +#include <linux/slab.h> > +#include <linux/types.h> > +#include "arm_big_little.h" > + > +static int dt_init_opp_table(struct device *cpu_dev) > +{ > + struct device_node *np = NULL; > + int count = 0, ret; > + > + for_each_child_of_node(of_find_node_by_path("/cpus"), np) { If of_find_node_by_path() returns NULL, there will be a NULL pointer dereference. > + if (count++ != cpu_dev->id) > + continue; > + if (!of_get_property(np, "operating-points", NULL)) > + return -ENODATA; > + > + cpu_dev->of_node = np; > + > + ret = of_init_opp_table(cpu_dev); > + if (ret) > + return ret; > + > + return 0; of_node_put() should be called on np before returning. Also, the reference count of the parent node should be decremented as well. These comments apply to the below function dt_get_transition_latency() too. > + } > + > + return -ENODEV; > +} > + > +static int dt_get_transition_latency(struct device *cpu_dev) > +{ > + struct device_node *np = NULL; > + u32 transition_latency = CPUFREQ_ETERNAL; > + int count = 0; > + > + for_each_child_of_node(of_find_node_by_path("/cpus"), np) { > + if (count++ != cpu_dev->id) > + continue; > + > + of_property_read_u32(np, "clock-latency", &transition_latency); > + return 0; > + } > + > + return -ENODEV; > +} -- Francesco
WARNING: multiple messages have this Message-ID (diff)
From: francescolavra.fl@gmail.com (Francesco Lavra) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH V2] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue Date: Sat, 13 Apr 2013 22:13:58 +0200 [thread overview] Message-ID: <5169BC86.7010905@gmail.com> (raw) In-Reply-To: <1f864ec505cae7c5daea3810a3c26e0f5cda38ea.1364290815.git.viresh.kumar@linaro.org> On 03/26/2013 10:51 AM, Viresh Kumar wrote: > big LITTLE is ARM's new Architecture focussing power/performance needs of modern > world. More information about big LITTLE can be found here: > > http://www.arm.com/products/processors/technologies/biglittleprocessing.php > http://lwn.net/Articles/481055/ > > In order to keep cpufreq support for all big LITTLE platforms simple/generic, > this patch tries to add a generic cpufreq driver layer for all big LITTLE > platforms. > > The driver is divided into two parts: > - Core driver: Generic and shared across all big LITTLE SoC's > - Glue drivers: Per platform drivers providing ops to the core driver > > This patch adds in a generic glue driver which would extract information from > Device Tree. > > Future SoC's can either reuse the DT glue or write their own depending on the > need. > > Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com> > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> [...] > diff --git a/drivers/cpufreq/arm_big_little_dt.c b/drivers/cpufreq/arm_big_little_dt.c > new file mode 100644 > index 0000000..452ff46 > --- /dev/null > +++ b/drivers/cpufreq/arm_big_little_dt.c > @@ -0,0 +1,92 @@ > +/* > + * Generic big.LITTLE CPUFreq Interface driver > + * > + * It provides necessary ops to arm_big_little cpufreq driver and gets > + * Frequency information from Device Tree. Freq table in DT must be in KHz. > + * > + * Copyright (C) 2013 Linaro. > + * Viresh Kumar <viresh.kumar@linaro.org> > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + * > + * This program is distributed "as is" WITHOUT ANY WARRANTY of any > + * kind, whether express or implied; without even the implied warranty > + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + */ > + > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > + > +#include <linux/cpufreq.h> > +#include <linux/device.h> > +#include <linux/export.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/opp.h> > +#include <linux/slab.h> > +#include <linux/types.h> > +#include "arm_big_little.h" > + > +static int dt_init_opp_table(struct device *cpu_dev) > +{ > + struct device_node *np = NULL; > + int count = 0, ret; > + > + for_each_child_of_node(of_find_node_by_path("/cpus"), np) { If of_find_node_by_path() returns NULL, there will be a NULL pointer dereference. > + if (count++ != cpu_dev->id) > + continue; > + if (!of_get_property(np, "operating-points", NULL)) > + return -ENODATA; > + > + cpu_dev->of_node = np; > + > + ret = of_init_opp_table(cpu_dev); > + if (ret) > + return ret; > + > + return 0; of_node_put() should be called on np before returning. Also, the reference count of the parent node should be decremented as well. These comments apply to the below function dt_get_transition_latency() too. > + } > + > + return -ENODEV; > +} > + > +static int dt_get_transition_latency(struct device *cpu_dev) > +{ > + struct device_node *np = NULL; > + u32 transition_latency = CPUFREQ_ETERNAL; > + int count = 0; > + > + for_each_child_of_node(of_find_node_by_path("/cpus"), np) { > + if (count++ != cpu_dev->id) > + continue; > + > + of_property_read_u32(np, "clock-latency", &transition_latency); > + return 0; > + } > + > + return -ENODEV; > +} -- Francesco
next prev parent reply other threads:[~2013-04-13 20:13 UTC|newest] Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-03-26 9:51 [PATCH V2] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue Viresh Kumar 2013-03-26 9:51 ` Viresh Kumar 2013-03-26 13:17 ` Rob Herring 2013-03-26 13:17 ` Rob Herring 2013-03-26 14:30 ` Viresh Kumar 2013-03-26 14:30 ` Viresh Kumar 2013-04-13 20:13 ` Francesco Lavra [this message] 2013-04-13 20:13 ` Francesco Lavra 2013-04-15 7:02 ` Viresh Kumar 2013-04-15 7:02 ` Viresh Kumar -- strict thread matches above, loose matches on Subject: below -- 2013-03-07 17:14 Viresh Kumar 2013-03-07 17:14 ` Viresh Kumar 2013-03-07 21:56 ` Guennadi Liakhovetski 2013-03-07 21:56 ` Guennadi Liakhovetski 2013-03-08 4:20 ` Viresh Kumar 2013-03-08 4:20 ` Viresh Kumar 2013-03-08 6:11 ` Guennadi Liakhovetski 2013-03-08 6:11 ` Guennadi Liakhovetski 2013-03-09 3:06 ` Viresh Kumar 2013-03-09 3:06 ` Viresh Kumar 2013-03-10 15:58 ` Francesco Lavra 2013-03-10 15:58 ` Francesco Lavra 2013-03-11 0:57 ` Viresh Kumar 2013-03-11 0:57 ` Viresh Kumar 2013-03-11 0:57 ` Viresh Kumar 2013-03-21 23:50 ` Rafael J. Wysocki 2013-03-21 23:50 ` Rafael J. Wysocki 2013-03-22 2:21 ` Viresh Kumar 2013-03-22 2:21 ` Viresh Kumar
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