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![Thomas Gleixner](/assets/img/avatar_default.png)
The target() callback must run on the affected cpu. This is achieved by temporarily setting the affinity of the calling thread to the requested CPU and reset it to the original affinity afterwards. That's racy vs. concurrent affinity settings for that thread resulting in code executing on the wrong CPU. Replace it by work_on_cpu(). All call pathes which invoke the callbacks are already protected against CPU hotplug. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: linux-pm@vger.kernel.org Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Tejun Heo <tj@kernel.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Len Brown <lenb@kernel.org> Link: http://lkml.kernel.org/r/20170412201042.958216363@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
186 lines
4.7 KiB
C
186 lines
4.7 KiB
C
/*
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* cpufreq driver for the SuperH processors.
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*
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* Copyright (C) 2002 - 2012 Paul Mundt
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* Copyright (C) 2002 M. R. Brown
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*
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* Clock framework bits from arch/avr32/mach-at32ap/cpufreq.c
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*
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* Copyright (C) 2004-2007 Atmel Corporation
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#define pr_fmt(fmt) "cpufreq: " fmt
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#include <linux/types.h>
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#include <linux/cpufreq.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/err.h>
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#include <linux/cpumask.h>
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#include <linux/cpu.h>
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#include <linux/smp.h>
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#include <linux/sched.h> /* set_cpus_allowed() */
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#include <linux/clk.h>
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#include <linux/percpu.h>
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#include <linux/sh_clk.h>
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static DEFINE_PER_CPU(struct clk, sh_cpuclk);
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struct cpufreq_target {
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struct cpufreq_policy *policy;
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unsigned int freq;
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};
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static unsigned int sh_cpufreq_get(unsigned int cpu)
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{
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return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 500) / 1000;
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}
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static long __sh_cpufreq_target(void *arg)
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{
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struct cpufreq_target *target = arg;
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struct cpufreq_policy *policy = target->policy;
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int cpu = policy->cpu;
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struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
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struct cpufreq_freqs freqs;
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struct device *dev;
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long freq;
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if (smp_processor_id() != cpu)
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return -ENODEV;
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dev = get_cpu_device(cpu);
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/* Convert target_freq from kHz to Hz */
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freq = clk_round_rate(cpuclk, target->freq * 1000);
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if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
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return -EINVAL;
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dev_dbg(dev, "requested frequency %u Hz\n", target->freq * 1000);
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freqs.old = sh_cpufreq_get(cpu);
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freqs.new = (freq + 500) / 1000;
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freqs.flags = 0;
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cpufreq_freq_transition_begin(target->policy, &freqs);
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clk_set_rate(cpuclk, freq);
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cpufreq_freq_transition_end(target->policy, &freqs, 0);
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dev_dbg(dev, "set frequency %lu Hz\n", freq);
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return 0;
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}
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/*
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* Here we notify other drivers of the proposed change and the final change.
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*/
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static int sh_cpufreq_target(struct cpufreq_policy *policy,
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unsigned int target_freq,
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unsigned int relation)
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{
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struct cpufreq_target data = { .policy = policy, .freq = target_freq };
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return work_on_cpu(policy->cpu, __sh_cpufreq_target, &data);
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}
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static int sh_cpufreq_verify(struct cpufreq_policy *policy)
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{
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struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);
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struct cpufreq_frequency_table *freq_table;
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freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
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if (freq_table)
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return cpufreq_frequency_table_verify(policy, freq_table);
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cpufreq_verify_within_cpu_limits(policy);
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policy->min = (clk_round_rate(cpuclk, 1) + 500) / 1000;
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policy->max = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
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cpufreq_verify_within_cpu_limits(policy);
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return 0;
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}
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static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
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{
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unsigned int cpu = policy->cpu;
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struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
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struct cpufreq_frequency_table *freq_table;
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struct device *dev;
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dev = get_cpu_device(cpu);
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cpuclk = clk_get(dev, "cpu_clk");
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if (IS_ERR(cpuclk)) {
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dev_err(dev, "couldn't get CPU clk\n");
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return PTR_ERR(cpuclk);
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}
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freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
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if (freq_table) {
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int result;
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result = cpufreq_table_validate_and_show(policy, freq_table);
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if (result)
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return result;
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} else {
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dev_notice(dev, "no frequency table found, falling back "
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"to rate rounding.\n");
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policy->min = policy->cpuinfo.min_freq =
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(clk_round_rate(cpuclk, 1) + 500) / 1000;
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policy->max = policy->cpuinfo.max_freq =
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(clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
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}
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policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
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dev_info(dev, "CPU Frequencies - Minimum %u.%03u MHz, "
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"Maximum %u.%03u MHz.\n",
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policy->min / 1000, policy->min % 1000,
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policy->max / 1000, policy->max % 1000);
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return 0;
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}
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static int sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
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{
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unsigned int cpu = policy->cpu;
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struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
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clk_put(cpuclk);
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return 0;
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}
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static struct cpufreq_driver sh_cpufreq_driver = {
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.name = "sh",
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.get = sh_cpufreq_get,
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.target = sh_cpufreq_target,
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.verify = sh_cpufreq_verify,
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.init = sh_cpufreq_cpu_init,
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.exit = sh_cpufreq_cpu_exit,
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.attr = cpufreq_generic_attr,
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};
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static int __init sh_cpufreq_module_init(void)
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{
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pr_notice("SuperH CPU frequency driver.\n");
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return cpufreq_register_driver(&sh_cpufreq_driver);
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}
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static void __exit sh_cpufreq_module_exit(void)
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{
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cpufreq_unregister_driver(&sh_cpufreq_driver);
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}
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module_init(sh_cpufreq_module_init);
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module_exit(sh_cpufreq_module_exit);
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MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
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MODULE_DESCRIPTION("cpufreq driver for SuperH");
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MODULE_LICENSE("GPL");
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