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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/unicore32/kernel/cpu-ucv2.c
10817 views
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/*

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 * linux/arch/unicore32/kernel/cpu-ucv2.c: clock scaling for the UniCore-II

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 *

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 * Code specific to PKUnity SoC and UniCore ISA

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 *

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 *	Maintained by GUAN Xue-tao <[email protected]>

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 *	Copyright (C) 2001-2010 Guan Xuetao

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 *

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 * This program is free software; you can redistribute it and/or modify

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 * it under the terms of the GNU General Public License version 2 as

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 * published by the Free Software Foundation.

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 */

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#include <linux/kernel.h>

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#include <linux/types.h>

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#include <linux/init.h>

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#include <linux/clk.h>

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#include <linux/cpufreq.h>

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#include <mach/hardware.h>

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static struct cpufreq_driver ucv2_driver;

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/* make sure that only the "userspace" governor is run

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 * -- anything else wouldn't make sense on this platform, anyway.

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 */

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int ucv2_verify_speed(struct cpufreq_policy *policy)

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{

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	if (policy->cpu)

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		return -EINVAL;

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	cpufreq_verify_within_limits(policy,

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			policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);

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	return 0;

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}

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static unsigned int ucv2_getspeed(unsigned int cpu)

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{

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	struct clk *mclk = clk_get(NULL, "MAIN_CLK");

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	if (cpu)

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		return 0;

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	return clk_get_rate(mclk)/1000;

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}

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static int ucv2_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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	unsigned int cur = ucv2_getspeed(0);

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	struct cpufreq_freqs freqs;

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	struct clk *mclk = clk_get(NULL, "MAIN_CLK");

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	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

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	if (!clk_set_rate(mclk, target_freq * 1000)) {

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		freqs.old = cur;

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		freqs.new = target_freq;

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		freqs.cpu = 0;

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	}

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	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

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	return 0;

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}

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static int __init ucv2_cpu_init(struct cpufreq_policy *policy)

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{

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	if (policy->cpu != 0)

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		return -EINVAL;

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	policy->cur = ucv2_getspeed(0);

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	policy->min = policy->cpuinfo.min_freq = 250000;

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	policy->max = policy->cpuinfo.max_freq = 1000000;

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	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;

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	return 0;

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}

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static struct cpufreq_driver ucv2_driver = {

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	.flags		= CPUFREQ_STICKY,

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	.verify		= ucv2_verify_speed,

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	.target		= ucv2_target,

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	.get		= ucv2_getspeed,

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	.init		= ucv2_cpu_init,

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	.name		= "UniCore-II",

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};

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static int __init ucv2_cpufreq_init(void)

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{

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	return cpufreq_register_driver(&ucv2_driver);

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}

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arch_initcall(ucv2_cpufreq_init);

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