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