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/*
* Copyright (C) 2004-2007 Atmel Corporation
*
* Based on MIPS implementation arch/mips/kernel/time.c
* Copyright 2001 MontaVista Software Inc.
*
* 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.
*/
/*#define DEBUG*/
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/slab.h>
static struct clk *cpuclk;
static struct cpufreq_frequency_table *freq_table;
static unsigned int at32_get_speed(unsigned int cpu)
{
/* No SMP support */
if (cpu)
return 0;
return (unsigned int)((clk_get_rate(cpuclk) + 500) / 1000);
}
static unsigned int ref_freq;
static unsigned long loops_per_jiffy_ref;
static int at32_set_target(struct cpufreq_policy *policy, unsigned int index)
{
struct cpufreq_freqs freqs;
freqs.old = at32_get_speed(0);
freqs.new = freq_table[index].frequency;
if (!ref_freq) {
ref_freq = freqs.old;
loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
}
cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
if (freqs.old < freqs.new)
boot_cpu_data.loops_per_jiffy = cpufreq_scale(
loops_per_jiffy_ref, ref_freq, freqs.new);
clk_set_rate(cpuclk, freqs.new * 1000);
if (freqs.new < freqs.old)
boot_cpu_data.loops_per_jiffy = cpufreq_scale(
loops_per_jiffy_ref, ref_freq, freqs.new);
cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
pr_debug("cpufreq: set frequency %u Hz\n", freqs.new * 1000);
return 0;
}
static int __init at32_cpufreq_driver_init(struct cpufreq_policy *policy)
{
unsigned int frequency, rate, min_freq;
int retval, steps, i;
if (policy->cpu != 0)
return -EINVAL;
cpuclk = clk_get(NULL, "cpu");
if (IS_ERR(cpuclk)) {
pr_debug("cpufreq: could not get CPU clk\n");
retval = PTR_ERR(cpuclk);
goto out_err;
}
min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
frequency = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
policy->cpuinfo.transition_latency = 0;
/*
* AVR32 CPU frequency rate scales in power of two between maximum and
* minimum, also add space for the table end marker.
*
* Further validate that the frequency is usable, and append it to the
* frequency table.
*/
steps = fls(frequency / min_freq) + 1;
freq_table = kzalloc(steps * sizeof(struct cpufreq_frequency_table),
GFP_KERNEL);
if (!freq_table) {
retval = -ENOMEM;
goto out_err_put_clk;
}
for (i = 0; i < (steps - 1); i++) {
rate = clk_round_rate(cpuclk, frequency * 1000) / 1000;
if (rate != frequency)
freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
else
freq_table[i].frequency = frequency;
frequency /= 2;
}
freq_table[steps - 1].frequency = CPUFREQ_TABLE_END;
retval = cpufreq_table_validate_and_show(policy, freq_table);
if (!retval) {
printk("cpufreq: AT32AP CPU frequency driver\n");
return 0;
}
kfree(freq_table);
out_err_put_clk:
clk_put(cpuclk);
out_err:
return retval;
}
static struct cpufreq_driver at32_driver = {
.name = "at32ap",
.init = at32_cpufreq_driver_init,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = at32_set_target,
.get = at32_get_speed,
.flags = CPUFREQ_STICKY,
};
static int __init at32_cpufreq_init(void)
{
return cpufreq_register_driver(&at32_driver);
}
late_initcall(at32_cpufreq_init);
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