219 lines
6.0 KiB
C
219 lines
6.0 KiB
C
/*
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* arch/sh/kernel/cpufreq.c
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*
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* cpufreq driver for the SuperH processors.
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*
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* Copyright (C) 2002, 2003, 2004, 2005 Paul Mundt
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* Copyright (C) 2002 M. R. Brown
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include <linux/types.h>
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#include <linux/cpufreq.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/delay.h>
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#include <linux/cpumask.h>
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#include <linux/smp.h>
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#include <asm/processor.h>
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#include <asm/watchdog.h>
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#include <asm/freq.h>
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#include <asm/io.h>
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/*
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* For SuperH, each policy change requires that we change the IFC, BFC, and
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* PFC at the same time. Here we define sane values that won't trash the
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* system.
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*
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* Note the max set is computed at runtime, we use the divisors that we booted
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* with to setup our maximum operating frequencies.
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*/
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struct clock_set {
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unsigned int ifc;
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unsigned int bfc;
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unsigned int pfc;
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} clock_sets[] = {
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#if defined(CONFIG_CPU_SH3) || defined(CONFIG_CPU_SH2)
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{ 0, 0, 0 }, /* not implemented yet */
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#elif defined(CONFIG_CPU_SH4)
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{ 4, 8, 8 }, /* min - IFC: 1/4, BFC: 1/8, PFC: 1/8 */
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{ 1, 2, 2 }, /* max - IFC: 1, BFC: 1/2, PFC: 1/2 */
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#endif
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};
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#define MIN_CLOCK_SET 0
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#define MAX_CLOCK_SET (ARRAY_SIZE(clock_sets) - 1)
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/*
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* For the time being, we only support two frequencies, which in turn are
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* aimed at the POWERSAVE and PERFORMANCE policies, which in turn are derived
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* directly from the respective min/max clock sets. Technically we could
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* support a wider range of frequencies, but these vary far too much for each
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* CPU subtype (and we'd have to construct a frequency table for each subtype).
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*
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* Maybe something to implement in the future..
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*/
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#define SH_FREQ_MAX 0
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#define SH_FREQ_MIN 1
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static struct cpufreq_frequency_table sh_freqs[] = {
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{ SH_FREQ_MAX, 0 },
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{ SH_FREQ_MIN, 0 },
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{ 0, CPUFREQ_TABLE_END },
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};
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static void sh_cpufreq_update_clocks(unsigned int set)
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{
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current_cpu_data.cpu_clock = current_cpu_data.master_clock / clock_sets[set].ifc;
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current_cpu_data.bus_clock = current_cpu_data.master_clock / clock_sets[set].bfc;
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current_cpu_data.module_clock = current_cpu_data.master_clock / clock_sets[set].pfc;
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current_cpu_data.loops_per_jiffy = loops_per_jiffy;
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}
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/* XXX: This needs to be split out per CPU and CPU subtype. */
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/*
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* Here we notify other drivers of the proposed change and the final change.
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*/
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static int sh_cpufreq_setstate(unsigned int cpu, unsigned int set)
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{
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unsigned short frqcr = ctrl_inw(FRQCR);
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cpumask_t cpus_allowed;
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struct cpufreq_freqs freqs;
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if (!cpu_online(cpu))
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return -ENODEV;
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cpus_allowed = current->cpus_allowed;
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set_cpus_allowed(current, cpumask_of_cpu(cpu));
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BUG_ON(smp_processor_id() != cpu);
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freqs.cpu = cpu;
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freqs.old = current_cpu_data.cpu_clock / 1000;
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freqs.new = (current_cpu_data.master_clock / clock_sets[set].ifc) / 1000;
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cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
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#if defined(CONFIG_CPU_SH3)
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frqcr |= (newstate & 0x4000) << 14;
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frqcr |= (newstate & 0x000c) << 2;
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#elif defined(CONFIG_CPU_SH4)
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/*
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* FRQCR.PLL2EN is 1, we need to allow the PLL to stabilize by
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* initializing the WDT.
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*/
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if (frqcr & (1 << 9)) {
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__u8 csr;
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/*
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* Set the overflow period to the highest available,
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* in this case a 1/4096 division ratio yields a 5.25ms
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* overflow period. See asm-sh/watchdog.h for more
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* information and a range of other divisors.
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*/
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csr = sh_wdt_read_csr();
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csr |= WTCSR_CKS_4096;
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sh_wdt_write_csr(csr);
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sh_wdt_write_cnt(0);
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}
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frqcr &= 0x0e00; /* Clear ifc, bfc, pfc */
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frqcr |= get_ifc_value(clock_sets[set].ifc) << 6;
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frqcr |= get_bfc_value(clock_sets[set].bfc) << 3;
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frqcr |= get_pfc_value(clock_sets[set].pfc);
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#endif
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ctrl_outw(frqcr, FRQCR);
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sh_cpufreq_update_clocks(set);
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set_cpus_allowed(current, cpus_allowed);
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cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
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return 0;
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}
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static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
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{
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unsigned int min_freq, max_freq;
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unsigned int ifc, bfc, pfc;
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if (!cpu_online(policy->cpu))
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return -ENODEV;
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/* Update our maximum clock set */
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get_current_frequency_divisors(&ifc, &bfc, &pfc);
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clock_sets[MAX_CLOCK_SET].ifc = ifc;
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clock_sets[MAX_CLOCK_SET].bfc = bfc;
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clock_sets[MAX_CLOCK_SET].pfc = pfc;
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/* Convert from Hz to kHz */
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max_freq = current_cpu_data.cpu_clock / 1000;
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min_freq = (current_cpu_data.master_clock / clock_sets[MIN_CLOCK_SET].ifc) / 1000;
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sh_freqs[SH_FREQ_MAX].frequency = max_freq;
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sh_freqs[SH_FREQ_MIN].frequency = min_freq;
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/* cpuinfo and default policy values */
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policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
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policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
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policy->cur = max_freq;
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return cpufreq_frequency_table_cpuinfo(policy, &sh_freqs[0]);
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}
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static int sh_cpufreq_verify(struct cpufreq_policy *policy)
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{
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return cpufreq_frequency_table_verify(policy, &sh_freqs[0]);
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}
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static int sh_cpufreq_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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unsigned int set, idx = 0;
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if (cpufreq_frequency_table_target(policy, &sh_freqs[0], target_freq, relation, &idx))
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return -EINVAL;
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set = (idx == SH_FREQ_MIN) ? MIN_CLOCK_SET : MAX_CLOCK_SET;
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sh_cpufreq_setstate(policy->cpu, set);
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return 0;
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}
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static struct cpufreq_driver sh_cpufreq_driver = {
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.owner = THIS_MODULE,
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.name = "SH cpufreq",
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.init = sh_cpufreq_cpu_init,
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.verify = sh_cpufreq_verify,
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.target = sh_cpufreq_target,
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};
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static int __init sh_cpufreq_init(void)
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{
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if (!current_cpu_data.cpu_clock)
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return -EINVAL;
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if (cpufreq_register_driver(&sh_cpufreq_driver))
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return -EINVAL;
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return 0;
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}
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static void __exit sh_cpufreq_exit(void)
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{
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cpufreq_unregister_driver(&sh_cpufreq_driver);
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}
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module_init(sh_cpufreq_init);
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module_exit(sh_cpufreq_exit);
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MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
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MODULE_DESCRIPTION("cpufreq driver for SuperH");
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MODULE_LICENSE("GPL");
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