On 03/26/2013 04:51 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@xxxxxxx> > Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx> > --- > V1->V2: > - It was reviewed here earlier: https://lkml.org/lkml/2013/3/4/614 > - It supports OPP library now and doesn't create a new binding for cpufreq table > - It doesn't add any dependency on cluster node in DT, rather we work with > existing cpu nodes, Documentation updated. > - cpu_dev used because of OPP library and hence dev_err/dbg/info used at > multiple places. > - Interface with glue driver updated a bit > - IS_ERR_OR_NULL replaced with IS_ERR for clk_get > - clk_get_sys used instead of clk_get and name of clk is also updated > - Few more minor cleanups done. > > It is pushed here: > > http://git.linaro.org/gitweb?p=people/vireshk/linux.git;a=shortlog;h=refs/heads/cpufreq-biglittle > > .../bindings/cpufreq/arm_big_little_dt.txt | 65 +++++ > MAINTAINERS | 11 + > drivers/cpufreq/Kconfig.arm | 12 + > drivers/cpufreq/Makefile | 4 + > drivers/cpufreq/arm_big_little.c | 282 +++++++++++++++++++++ > drivers/cpufreq/arm_big_little.h | 40 +++ > drivers/cpufreq/arm_big_little_dt.c | 92 +++++++ > 7 files changed, 506 insertions(+) > create mode 100644 Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt > create mode 100644 drivers/cpufreq/arm_big_little.c > create mode 100644 drivers/cpufreq/arm_big_little.h > create mode 100644 drivers/cpufreq/arm_big_little_dt.c > > diff --git a/Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt b/Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt > new file mode 100644 > index 0000000..34a460d > --- /dev/null > +++ b/Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt > @@ -0,0 +1,65 @@ > +Generic ARM big LITTLE cpufreq driver's DT glue > +----------------------------------------------- > + > +This is DT specific glue layer for generic cpufreq driver for big LITTLE > +systems. I fail to see anything bL specific here. This is just multi-cluster, but even for that I don't see anything new other than simply allowing per cpu or per cluster opp's. The fact that we have one opp for a cluster is simply an implementation decision in CortexA cores. > + > +Both required and optional properties listed below must be defined > +under node /cpus/cpu@x. Where x is the first cpu inside a cluster. > + > +NOTE: Cpus should boot in the order specified in DT and all cpus for a cluster > +must be present contiguously. Generic DT driver will check only node 'x' for > +cpu:x. The OS cannot necessarily control the order. The OS should be able to boot on which ever core comes up first. > + > +Required properties: > +- operating-points: Refer to Documentation/devicetree/bindings/power/opp.txt > + for details > + > +Optional properties: > +- clock-latency: Specify the possible maximum transition latency for clock, > + in unit of nanoseconds. Don't we already have "transition-latency" defined? Don't create something new. Ideally, this should have had "-ns" appended, but the binding is already defined. > + > +Examples: > + > +cpus { > + #address-cells = <1>; > + #size-cells = <0>; > + > + cpu@0 { > + compatible = "arm,cortex-a15"; > + reg = <0>; > + next-level-cache = <&L2>; > + operating-points = < > + /* kHz uV */ > + 792000 1100000 > + 396000 950000 > + 198000 850000 > + >; > + clock-latency = <61036>; /* two CLK32 periods */ > + }; > + > + cpu@1 { > + compatible = "arm,cortex-a15"; > + reg = <1>; > + next-level-cache = <&L2>; > + }; > + > + cpu@100 { > + compatible = "arm,cortex-a7"; > + reg = <100>; > + next-level-cache = <&L2>; > + operating-points = < > + /* kHz uV */ > + 792000 950000 > + 396000 750000 > + 198000 450000 > + >; > + clock-latency = <61036>; /* two CLK32 periods */ > + }; > + > + cpu@101 { > + compatible = "arm,cortex-a7"; > + reg = <101>; > + next-level-cache = <&L2>; > + }; > +}; > diff --git a/MAINTAINERS b/MAINTAINERS > index 4cf5fd3..4071b71 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -2206,6 +2206,17 @@ S: Maintained > F: drivers/cpufreq/ > F: include/linux/cpufreq.h > > +CPU FREQUENCY DRIVERS - ARM BIG LITTLE > +M: Viresh Kumar <viresh.kumar@xxxxxxxxxx> > +M: Sudeep KarkadaNagesha <sudeep.karkadanagesha@xxxxxxx> > +L: cpufreq@xxxxxxxxxxxxxxx > +L: linux-pm@xxxxxxxxxxxxxxx > +W: http://www.arm.com/products/processors/technologies/biglittleprocessing.php > +S: Maintained > +F: drivers/cpufreq/arm_big_little.h > +F: drivers/cpufreq/arm_big_little.c > +F: drivers/cpufreq/arm_big_little_dt.c > + > CPUID/MSR DRIVER > M: "H. Peter Anvin" <hpa@xxxxxxxxx> > S: Maintained > diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm > index 030ddf6..87b7e48 100644 > --- a/drivers/cpufreq/Kconfig.arm > +++ b/drivers/cpufreq/Kconfig.arm > @@ -2,6 +2,18 @@ > # ARM CPU Frequency scaling drivers > # > > +config ARM_BIG_LITTLE_CPUFREQ > + tristate > + depends on ARM_CPU_TOPOLOGY > + > +config ARM_DT_BL_CPUFREQ > + tristate "Generic ARM big LITTLE CPUfreq driver probed via DT" > + select ARM_BIG_LITTLE_CPUFREQ > + depends on OF && HAVE_CLK > + help > + This enables the Generic CPUfreq driver for ARM big.LITTLE platform. > + This gets frequency tables from DT. > + > config ARM_OMAP2PLUS_CPUFREQ > bool "TI OMAP2+" > depends on ARCH_OMAP2PLUS > diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile > index 863fd18..d1b0832 100644 > --- a/drivers/cpufreq/Makefile > +++ b/drivers/cpufreq/Makefile > @@ -44,6 +44,10 @@ obj-$(CONFIG_X86_INTEL_PSTATE) += intel_pstate.o > > ################################################################################## > # ARM SoC drivers > +obj-$(CONFIG_ARM_BIG_LITTLE_CPUFREQ) += arm_big_little.o > +# big LITTLE per platform glues. Keep DT_BL_CPUFREQ as the last entry in all big > +# LITTLE drivers, so that it is probed last. > +obj-$(CONFIG_ARM_DT_BL_CPUFREQ) += arm_big_little_dt.o > obj-$(CONFIG_UX500_SOC_DB8500) += dbx500-cpufreq.o > obj-$(CONFIG_ARM_S3C2416_CPUFREQ) += s3c2416-cpufreq.o > obj-$(CONFIG_ARM_S3C64XX_CPUFREQ) += s3c64xx-cpufreq.o > diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c > new file mode 100644 > index 0000000..1d29d1a > --- /dev/null > +++ b/drivers/cpufreq/arm_big_little.c > @@ -0,0 +1,282 @@ > +/* > + * ARM big.LITTLE Platforms CPUFreq support What is specific to bL? This looks like just a multi-cluster cpufreq driver and should be generalized to that. Also, why can't the existing cpufreq-cpu0 driver be extended to support this? > + * Copyright (C) 2013 ARM Ltd. > + * Sudeep KarkadaNagesha <sudeep.karkadanagesha@xxxxxxx> > + * > + * Copyright (C) 2013 Linaro. > + * Viresh Kumar <viresh.kumar@xxxxxxxxxx> > + * > + * 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/clk.h> > +#include <linux/cpu.h> > +#include <linux/cpufreq.h> > +#include <linux/cpumask.h> > +#include <linux/export.h> > +#include <linux/of_platform.h> > +#include <linux/opp.h> > +#include <linux/slab.h> > +#include <linux/topology.h> > +#include <linux/types.h> > + > +#include "arm_big_little.h" > + > +/* Currently we support only two clusters */ > +#define MAX_CLUSTERS 2 Why? Because that is what the define is or there are other limitations? Seems like this could and should be dynamically discovered with DT. Rob -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
