unicore2-cpufreq.c 1.73 KB
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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 * clock scaling for the UniCore-II
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 *
 * Code specific to PKUnity SoC and UniCore ISA
 *
 *	Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
 *	Copyright (C) 2001-2010 Guan Xuetao
 */

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#include <linux/err.h>
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#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/clk.h>
#include <linux/cpufreq.h>

#include <mach/hardware.h>

static struct cpufreq_driver ucv2_driver;

/* make sure that only the "userspace" governor is run
 * -- anything else wouldn't make sense on this platform, anyway.
 */
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static int ucv2_verify_speed(struct cpufreq_policy *policy)
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{
	if (policy->cpu)
		return -EINVAL;

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	cpufreq_verify_within_cpu_limits(policy);
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	return 0;
}

static int ucv2_target(struct cpufreq_policy *policy,
			 unsigned int target_freq,
			 unsigned int relation)
{
	struct cpufreq_freqs freqs;
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	int ret;
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	freqs.old = policy->cur;
	freqs.new = target_freq;
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	cpufreq_freq_transition_begin(policy, &freqs);
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	ret = clk_set_rate(policy->clk, target_freq * 1000);
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	cpufreq_freq_transition_end(policy, &freqs, ret);
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	return ret;
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}

static int __init ucv2_cpu_init(struct cpufreq_policy *policy)
{
	if (policy->cpu != 0)
		return -EINVAL;
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	policy->min = policy->cpuinfo.min_freq = 250000;
	policy->max = policy->cpuinfo.max_freq = 1000000;
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	policy->clk = clk_get(NULL, "MAIN_CLK");
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	return PTR_ERR_OR_ZERO(policy->clk);
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}

static struct cpufreq_driver ucv2_driver = {
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	.flags		= CPUFREQ_STICKY | CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
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	.verify		= ucv2_verify_speed,
	.target		= ucv2_target,
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	.get		= cpufreq_generic_get,
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	.init		= ucv2_cpu_init,
	.name		= "UniCore-II",
};

static int __init ucv2_cpufreq_init(void)
{
	return cpufreq_register_driver(&ucv2_driver);
}

arch_initcall(ucv2_cpufreq_init);