sh-cpufreq.c 4.5 KB
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/*
 * cpufreq driver for the SuperH processors.
 *
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 * Copyright (C) 2002 - 2012 Paul Mundt
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 * Copyright (C) 2002 M. R. Brown
 *
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 * Clock framework bits from arch/avr32/mach-at32ap/cpufreq.c
 *
 *   Copyright (C) 2004-2007 Atmel Corporation
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * 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>
#include <linux/cpufreq.h>
#include <linux/kernel.h>
#include <linux/module.h>
#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>
#include <linux/sh_clk.h>
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static DEFINE_PER_CPU(struct clk, sh_cpuclk);
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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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}

/*
 * Here we notify other drivers of the proposed change and the final change.
 */
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static int sh_cpufreq_target(struct cpufreq_policy *policy,
			     unsigned int target_freq,
			     unsigned int relation)
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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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	cpumask_t cpus_allowed;
	struct cpufreq_freqs freqs;
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	struct device *dev;
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	long freq;
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	cpus_allowed = current->cpus_allowed;
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	set_cpus_allowed_ptr(current, cpumask_of(cpu));
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	BUG_ON(smp_processor_id() != cpu);

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	dev = get_cpu_device(cpu);

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	/* Convert target_freq from kHz to Hz */
	freq = clk_round_rate(cpuclk, target_freq * 1000);
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	if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
		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);
	freqs.new	= (freq + 500) / 1000;
	freqs.flags	= 0;

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	cpufreq_freq_transition_begin(policy, &freqs);
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	set_cpus_allowed_ptr(current, &cpus_allowed);
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	clk_set_rate(cpuclk, freq);
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	cpufreq_freq_transition_end(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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static int sh_cpufreq_verify(struct cpufreq_policy *policy)
{
	struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);
	struct cpufreq_frequency_table *freq_table;

	freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
	if (freq_table)
		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;
	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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static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
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	unsigned int cpu = policy->cpu;
	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);

	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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	freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
	if (freq_table) {
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		int result;
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		result = cpufreq_table_validate_and_show(policy, freq_table);
		if (result)
			return result;
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	} else {
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		dev_notice(dev, "no frequency table found, falling back "
			   "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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static int sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
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{
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	unsigned int cpu = policy->cpu;
	struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
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	clk_put(cpuclk);
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	return 0;
}

static struct cpufreq_driver sh_cpufreq_driver = {
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	.name		= "sh",
	.get		= sh_cpufreq_get,
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	.target		= sh_cpufreq_target,
	.verify		= sh_cpufreq_verify,
	.init		= sh_cpufreq_cpu_init,
	.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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{
	cpufreq_unregister_driver(&sh_cpufreq_driver);
}

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module_init(sh_cpufreq_module_init);
module_exit(sh_cpufreq_module_exit);
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MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
MODULE_DESCRIPTION("cpufreq driver for SuperH");
MODULE_LICENSE("GPL");