127 lines
3.1 KiB
C
127 lines
3.1 KiB
C
/*
|
|
* 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 cpufreq_frequency_table *freq_table;
|
|
|
|
static unsigned int ref_freq;
|
|
static unsigned long loops_per_jiffy_ref;
|
|
|
|
static int at32_set_target(struct cpufreq_policy *policy, unsigned int index)
|
|
{
|
|
unsigned int old_freq, new_freq;
|
|
|
|
old_freq = policy->cur;
|
|
new_freq = freq_table[index].frequency;
|
|
|
|
if (!ref_freq) {
|
|
ref_freq = old_freq;
|
|
loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
|
|
}
|
|
|
|
if (old_freq < new_freq)
|
|
boot_cpu_data.loops_per_jiffy = cpufreq_scale(
|
|
loops_per_jiffy_ref, ref_freq, new_freq);
|
|
clk_set_rate(policy->clk, new_freq * 1000);
|
|
if (new_freq < old_freq)
|
|
boot_cpu_data.loops_per_jiffy = cpufreq_scale(
|
|
loops_per_jiffy_ref, ref_freq, new_freq);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int at32_cpufreq_driver_init(struct cpufreq_policy *policy)
|
|
{
|
|
unsigned int frequency, rate, min_freq;
|
|
struct clk *cpuclk;
|
|
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;
|
|
}
|
|
|
|
policy->clk = cpuclk;
|
|
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 = cpufreq_generic_get,
|
|
.flags = CPUFREQ_STICKY,
|
|
};
|
|
|
|
static int __init at32_cpufreq_init(void)
|
|
{
|
|
return cpufreq_register_driver(&at32_driver);
|
|
}
|
|
late_initcall(at32_cpufreq_init);
|