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/*
* CPU frequency scaling for DaVinci
*
* Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
*
* Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
*
* Copyright (C) 2005 Nokia Corporation
* Written by Tony Lindgren <tony@atomide.com>
*
* Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
*
* Copyright (C) 2007-2008 Texas Instruments, Inc.
* Updated to support OMAP3
* Rajendra Nayak <rnayak@ti.com>
*
* 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.
*/
#include <linux/types.h>
#include <linux/cpufreq.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/platform_data/davinci-cpufreq.h>
#include <linux/platform_device.h>
#include <linux/export.h>
struct davinci_cpufreq {
struct device *dev;
struct clk *armclk;
struct clk *asyncclk;
unsigned long asyncrate;
};
static struct davinci_cpufreq cpufreq;
static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)
{
struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
struct clk *armclk = cpufreq.armclk;
unsigned int old_freq, new_freq;
int ret = 0;
old_freq = policy->cur;
new_freq = pdata->freq_table[idx].frequency;
/* if moving to higher frequency, up the voltage beforehand */
if (pdata->set_voltage && new_freq > old_freq) {
ret = pdata->set_voltage(idx);
if (ret)
return ret;
}
ret = clk_set_rate(armclk, new_freq * 1000);
if (ret)
return ret;
if (cpufreq.asyncclk) {
ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
if (ret)
return ret;
}
/* if moving to lower freq, lower the voltage after lowering freq */
if (pdata->set_voltage && new_freq < old_freq)
pdata->set_voltage(idx);
return 0;
}
static int davinci_cpu_init(struct cpufreq_policy *policy)
{
int result = 0;
struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
struct cpufreq_frequency_table *freq_table = pdata->freq_table;
if (policy->cpu != 0)
return -EINVAL;
/* Finish platform specific initialization */
if (pdata->init) {
result = pdata->init();
if (result)
return result;
}
policy->clk = cpufreq.armclk;
/*
* Time measurement across the target() function yields ~1500-1800us
* time taken with no drivers on notification list.
* Setting the latency to 2000 us to accommodate addition of drivers
* to pre/post change notification list.
*/
return cpufreq_generic_init(policy, freq_table, 2000 * 1000);
}
static struct cpufreq_driver davinci_driver = {
.flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = davinci_target,
.get = cpufreq_generic_get,
.init = davinci_cpu_init,
.name = "davinci",
.attr = cpufreq_generic_attr,
};
static int __init davinci_cpufreq_probe(struct platform_device *pdev)
{
struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
struct clk *asyncclk;
if (!pdata)
return -EINVAL;
if (!pdata->freq_table)
return -EINVAL;
cpufreq.dev = &pdev->dev;
cpufreq.armclk = clk_get(NULL, "arm");
if (IS_ERR(cpufreq.armclk)) {
dev_err(cpufreq.dev, "Unable to get ARM clock\n");
return PTR_ERR(cpufreq.armclk);
}
asyncclk = clk_get(cpufreq.dev, "async");
if (!IS_ERR(asyncclk)) {
cpufreq.asyncclk = asyncclk;
cpufreq.asyncrate = clk_get_rate(asyncclk);
}
return cpufreq_register_driver(&davinci_driver);
}
static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
{
clk_put(cpufreq.armclk);
if (cpufreq.asyncclk)
clk_put(cpufreq.asyncclk);
return cpufreq_unregister_driver(&davinci_driver);
}
static struct platform_driver davinci_cpufreq_driver = {
.driver = {
.name = "cpufreq-davinci",
},
.remove = __exit_p(davinci_cpufreq_remove),
};
int __init davinci_cpufreq_init(void)
{
return platform_driver_probe(&davinci_cpufreq_driver,
davinci_cpufreq_probe);
}
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