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 --- 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%3Ba=shortlog%3Bh=ref...

.../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. + +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. + +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. + +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@linaro.org +M: Sudeep KarkadaNagesha sudeep.karkadanagesha@arm.com +L: cpufreq@vger.kernel.org +L: linux-pm@vger.kernel.org +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@zytor.com 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 + * + * Copyright (C) 2013 ARM Ltd. + * Sudeep KarkadaNagesha sudeep.karkadanagesha@arm.com + * + * 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/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 + +static struct cpufreq_arm_bL_ops *arm_bL_ops; +static struct clk *clk[MAX_CLUSTERS]; +static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS]; +static atomic_t cluster_usage[MAX_CLUSTERS] = {ATOMIC_INIT(0), ATOMIC_INIT(0)}; + +static int cpu_to_cluster(int cpu) +{ + return topology_physical_package_id(cpu); +} + +static unsigned int bL_cpufreq_get(unsigned int cpu) +{ + u32 cur_cluster = cpu_to_cluster(cpu); + + return clk_get_rate(clk[cur_cluster]) / 1000; +} + +/* Validate policy frequency range */ +static int bL_cpufreq_verify_policy(struct cpufreq_policy *policy) +{ + u32 cur_cluster = cpu_to_cluster(policy->cpu); + + return cpufreq_frequency_table_verify(policy, freq_table[cur_cluster]); +} + +/* Set clock frequency */ +static int bL_cpufreq_set_target(struct cpufreq_policy *policy, + unsigned int target_freq, unsigned int relation) +{ + struct cpufreq_freqs freqs; + u32 cpu = policy->cpu, freq_tab_idx, cur_cluster; + int ret = 0; + + cur_cluster = cpu_to_cluster(policy->cpu); + + freqs.old = bL_cpufreq_get(policy->cpu); + + /* Determine valid target frequency using freq_table */ + cpufreq_frequency_table_target(policy, freq_table[cur_cluster], + target_freq, relation, &freq_tab_idx); + freqs.new = freq_table[cur_cluster][freq_tab_idx].frequency; + + freqs.cpu = policy->cpu; + + pr_debug("%s: cpu: %d, cluster: %d, oldfreq: %d, target freq: %d, new freq: %d\n", + __func__, cpu, cur_cluster, freqs.old, target_freq, + freqs.new); + + if (freqs.old == freqs.new) + return 0; + + for_each_cpu(freqs.cpu, policy->cpus) + cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); + + ret = clk_set_rate(clk[cur_cluster], freqs.new * 1000); + if (ret) { + pr_err("clk_set_rate failed: %d\n", ret); + return ret; + } + + policy->cur = freqs.new; + + for_each_cpu(freqs.cpu, policy->cpus) + cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); + + return ret; +} + +static void put_cluster_clk_and_freq_table(struct device *cpu_dev) +{ + u32 cluster = cpu_to_cluster(cpu_dev->id); + + if (!atomic_dec_return(&cluster_usage[cluster])) { + clk_put(clk[cluster]); + opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]); + dev_dbg(cpu_dev, "%s: cluster: %d\n", __func__, cluster); + } +} + +static int get_cluster_clk_and_freq_table(struct device *cpu_dev) +{ + u32 cluster = cpu_to_cluster(cpu_dev->id); + char name[14] = "cpu-cluster."; + int ret; + + if (atomic_inc_return(&cluster_usage[cluster]) != 1) + return 0; + + ret = arm_bL_ops->init_opp_table(cpu_dev); + if (ret) { + dev_err(cpu_dev, "%s: init_opp_table failed, cpu: %d, err: %d\n", + __func__, cpu_dev->id, ret); + goto atomic_dec; + } + + ret = opp_init_cpufreq_table(cpu_dev, &freq_table[cluster]); + if (ret) { + dev_err(cpu_dev, "%s: failed to init cpufreq table, cpu: %d, err: %d\n", + __func__, cpu_dev->id, ret); + goto atomic_dec; + } + + name[12] = cluster + '0'; + clk[cluster] = clk_get_sys(name, NULL); + if (!IS_ERR(clk[cluster])) { + dev_dbg(cpu_dev, "%s: clk: %p & freq table: %p, cluster: %d\n", + __func__, clk[cluster], freq_table[cluster], + cluster); + return 0; + } + + dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d, cluster: %d\n", + __func__, cpu_dev->id, cluster); + ret = PTR_ERR(clk[cluster]); + opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]); + +atomic_dec: + atomic_dec(&cluster_usage[cluster]); + dev_err(cpu_dev, "%s: Failed to get data for cluster: %d\n", __func__, + cluster); + return ret; +} + +/* Per-CPU initialization */ +static int bL_cpufreq_init(struct cpufreq_policy *policy) +{ + u32 cur_cluster = cpu_to_cluster(policy->cpu); + struct device *cpu_dev; + int ret; + + cpu_dev = get_cpu_device(policy->cpu); + if (!cpu_dev) { + pr_err("%s: failed to get cpu%d device\n", __func__, + policy->cpu); + return -ENODEV; + } + + ret = get_cluster_clk_and_freq_table(cpu_dev); + if (ret) + return ret; + + ret = cpufreq_frequency_table_cpuinfo(policy, freq_table[cur_cluster]); + if (ret) { + dev_err(cpu_dev, "CPU %d, cluster: %d invalid freq table\n", + policy->cpu, cur_cluster); + put_cluster_clk_and_freq_table(cpu_dev); + return ret; + } + + cpufreq_frequency_table_get_attr(freq_table[cur_cluster], policy->cpu); + + if (arm_bL_ops->get_transition_latency) + policy->cpuinfo.transition_latency = + arm_bL_ops->get_transition_latency(cpu_dev); + else + policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; + + policy->cur = bL_cpufreq_get(policy->cpu); + + cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu)); + + dev_info(cpu_dev, "CPU %d initialized\n", policy->cpu); + return 0; +} + +static int bL_cpufreq_exit(struct cpufreq_policy *policy) +{ + struct device *cpu_dev; + + cpu_dev = get_cpu_device(policy->cpu); + if (!cpu_dev) { + pr_err("%s: failed to get cpu%d device\n", __func__, + policy->cpu); + return -ENODEV; + } + + put_cluster_clk_and_freq_table(cpu_dev); + dev_dbg(cpu_dev, "%s: Exited, cpu: %d\n", __func__, policy->cpu); + + return 0; +} + +/* Export freq_table to sysfs */ +static struct freq_attr *bL_cpufreq_attr[] = { + &cpufreq_freq_attr_scaling_available_freqs, + NULL, +}; + +static struct cpufreq_driver bL_cpufreq_driver = { + .name = "arm-big-little", + .flags = CPUFREQ_STICKY, + .verify = bL_cpufreq_verify_policy, + .target = bL_cpufreq_set_target, + .get = bL_cpufreq_get, + .init = bL_cpufreq_init, + .exit = bL_cpufreq_exit, + .have_multiple_policies = true, + .attr = bL_cpufreq_attr, +}; + +int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops) +{ + int ret; + + if (arm_bL_ops) { + pr_debug("%s: Already registered: %s, exiting\n", __func__, + arm_bL_ops->name); + return -EBUSY; + } + + if (!ops || !strlen(ops->name) || !ops->init_opp_table) { + pr_err("%s: Invalid arm_bL_ops, exiting\n", __func__); + return -ENODEV; + } + + arm_bL_ops = ops; + + ret = cpufreq_register_driver(&bL_cpufreq_driver); + if (ret) { + pr_info("%s: Failed registering platform driver: %s, err: %d\n", + __func__, ops->name, ret); + arm_bL_ops = NULL; + } else { + pr_info("%s: Registered platform driver: %s\n", __func__, + ops->name); + } + + return ret; +} +EXPORT_SYMBOL_GPL(bL_cpufreq_register); + +void bL_cpufreq_unregister(struct cpufreq_arm_bL_ops *ops) +{ + if (arm_bL_ops != ops) { + pr_err("%s: Registered with: %s, can't unregister, exiting\n", + __func__, arm_bL_ops->name); + return; + } + + cpufreq_unregister_driver(&bL_cpufreq_driver); + pr_info("%s: Un-registered platform driver: %s\n", __func__, + arm_bL_ops->name); + arm_bL_ops = NULL; +} +EXPORT_SYMBOL_GPL(bL_cpufreq_unregister); diff --git a/drivers/cpufreq/arm_big_little.h b/drivers/cpufreq/arm_big_little.h new file mode 100644 index 0000000..70f18fc --- /dev/null +++ b/drivers/cpufreq/arm_big_little.h @@ -0,0 +1,40 @@ +/* + * ARM big.LITTLE platform's CPUFreq header file + * + * Copyright (C) 2013 ARM Ltd. + * Sudeep KarkadaNagesha sudeep.karkadanagesha@arm.com + * + * 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. + */ +#ifndef CPUFREQ_ARM_BIG_LITTLE_H +#define CPUFREQ_ARM_BIG_LITTLE_H + +#include <linux/cpufreq.h> +#include <linux/device.h> +#include <linux/types.h> + +struct cpufreq_arm_bL_ops { + char name[CPUFREQ_NAME_LEN]; + int (*get_transition_latency)(struct device *cpu_dev); + + /* + * This must set opp table for cpu_dev in a similar way as done by + * of_init_opp_table(). + */ + int (*init_opp_table)(struct device *cpu_dev); +}; + +int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops); +void bL_cpufreq_unregister(struct cpufreq_arm_bL_ops *ops); + +#endif /* CPUFREQ_ARM_BIG_LITTLE_H */ 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 (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; + } + + 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; +} + +static struct cpufreq_arm_bL_ops dt_bL_ops = { + .name = "dt-bl", + .get_transition_latency = dt_get_transition_latency, + .init_opp_table = dt_init_opp_table, +}; + +static int generic_bL_init(void) +{ + return bL_cpufreq_register(&dt_bL_ops); +} +module_init(generic_bL_init); + +static void generic_bL_exit(void) +{ + return bL_cpufreq_unregister(&dt_bL_ops); +} +module_exit(generic_bL_exit); + +MODULE_AUTHOR("Viresh Kumar viresh.kumar@linaro.org"); +MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT"); +MODULE_LICENSE("GPL");