e3f91ca481
The loops_per_jiffy variable isn't updated when cpufreq changes the CPU frequency. This could cause udelay() and friends to produce wrong delays. Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
125 lines
3.1 KiB
C
125 lines
3.1 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 <asm/system.h>
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static struct clk *cpuclk;
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static int at32_verify_speed(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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cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
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policy->cpuinfo.max_freq);
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return 0;
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}
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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,
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unsigned int target_freq,
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unsigned int relation)
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{
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struct cpufreq_freqs freqs;
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long freq;
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/* Convert target_freq from kHz to Hz */
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freq = clk_round_rate(cpuclk, target_freq * 1000);
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/* Check if policy->min <= new_freq <= policy->max */
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if(freq < (policy->min * 1000) || freq > (policy->max * 1000))
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return -EINVAL;
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pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
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freqs.old = at32_get_speed(0);
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freqs.new = (freq + 500) / 1000;
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freqs.cpu = 0;
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freqs.flags = 0;
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if (!ref_freq) {
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ref_freq = freqs.old;
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loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
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}
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cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
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if (freqs.old < freqs.new)
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boot_cpu_data.loops_per_jiffy = cpufreq_scale(
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loops_per_jiffy_ref, ref_freq, freqs.new);
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clk_set_rate(cpuclk, freq);
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if (freqs.new < freqs.old)
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boot_cpu_data.loops_per_jiffy = cpufreq_scale(
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loops_per_jiffy_ref, ref_freq, freqs.new);
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cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
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pr_debug("cpufreq: set frequency %lu Hz\n", freq);
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return 0;
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}
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static int __init at32_cpufreq_driver_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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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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return PTR_ERR(cpuclk);
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}
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policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
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policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
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policy->cpuinfo.transition_latency = 0;
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policy->cur = at32_get_speed(0);
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policy->min = policy->cpuinfo.min_freq;
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policy->max = policy->cpuinfo.max_freq;
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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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static struct cpufreq_driver at32_driver = {
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.name = "at32ap",
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.owner = THIS_MODULE,
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.init = at32_cpufreq_driver_init,
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.verify = at32_verify_speed,
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.target = 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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