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author | Viresh Kumar <viresh.kumar@linaro.org> | 2013-04-01 12:57:49 +0000 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-04-02 15:26:32 +0200 |
commit | 8a67f0ef2b684b34162d39e8f436fe39e9635a19 (patch) | |
tree | dc997ac3064c69e775485213b824e7c3efeb5b99 /drivers/cpufreq/arm_big_little.c | |
parent | eb2f50ff93f08c8001d0d7e1148948ba80989aaf (diff) | |
download | op-kernel-dev-8a67f0ef2b684b34162d39e8f436fe39e9635a19.zip op-kernel-dev-8a67f0ef2b684b34162d39e8f436fe39e9635a19.tar.gz |
cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
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>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/arm_big_little.c')
-rw-r--r-- | drivers/cpufreq/arm_big_little.c | 282 |
1 files changed, 282 insertions, 0 deletions
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); |