LXR linux/arch/sh/kernel/cpufreq.c

   1/*
   2 * arch/sh/kernel/cpufreq.c
   3 *
   4 * cpufreq driver for the SuperH processors.
   5 *
   6 * Copyright (C) 2002 - 2007 Paul Mundt
   7 * Copyright (C) 2002 M. R. Brown
   8 *
   9 * Clock framework bits from arch/avr32/mach-at32ap/cpufreq.c
  10 *
  11 *   Copyright (C) 2004-2007 Atmel Corporation
  12 *
  13 * This file is subject to the terms and conditions of the GNU General Public
  14 * License.  See the file "COPYING" in the main directory of this archive
  15 * for more details.
  16 */
  17#include <linux/types.h>
  18#include <linux/cpufreq.h>
  19#include <linux/kernel.h>
  20#include <linux/module.h>
  21#include <linux/init.h>
  22#include <linux/err.h>
  23#include <linux/cpumask.h>
  24#include <linux/smp.h>
  25#include <linux/sched.h>        /* set_cpus_allowed() */
  26#include <linux/clk.h>
  27
  28static struct clk *cpuclk;
  29
  30static unsigned int sh_cpufreq_get(unsigned int cpu)
  31{
  32        return (clk_get_rate(cpuclk) + 500) / 1000;
  33}
  34
  35/*
  36 * Here we notify other drivers of the proposed change and the final change.
  37 */
  38static int sh_cpufreq_target(struct cpufreq_policy *policy,
  39                             unsigned int target_freq,
  40                             unsigned int relation)
  41{
  42        unsigned int cpu = policy->cpu;
  43        cpumask_t cpus_allowed;
  44        struct cpufreq_freqs freqs;
  45        long freq;
  46
  47        if (!cpu_online(cpu))
  48                return -ENODEV;
  49
  50        cpus_allowed = current->cpus_allowed;
  51        set_cpus_allowed(current, cpumask_of_cpu(cpu));
  52
  53        BUG_ON(smp_processor_id() != cpu);
  54
  55        /* Convert target_freq from kHz to Hz */
  56        freq = clk_round_rate(cpuclk, target_freq * 1000);
  57
  58        if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
  59                return -EINVAL;
  60
  61        pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
  62
  63        freqs.cpu       = cpu;
  64        freqs.old       = sh_cpufreq_get(cpu);
  65        freqs.new       = (freq + 500) / 1000;
  66        freqs.flags     = 0;
  67
  68        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  69        set_cpus_allowed(current, cpus_allowed);
  70        clk_set_rate(cpuclk, freq);
  71        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  72
  73        pr_debug("cpufreq: set frequency %lu Hz\n", freq);
  74
  75        return 0;
  76}
  77
  78static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
  79{
  80        if (!cpu_online(policy->cpu))
  81                return -ENODEV;
  82
  83        cpuclk = clk_get(NULL, "cpu_clk");
  84        if (IS_ERR(cpuclk)) {
  85                printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
  86                return PTR_ERR(cpuclk);
  87        }
  88
  89        /* cpuinfo and default policy values */
  90        policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
  91        policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
  92        policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
  93
  94        policy->cur             = sh_cpufreq_get(policy->cpu);
  95        policy->min             = policy->cpuinfo.min_freq;
  96        policy->max             = policy->cpuinfo.max_freq;
  97
  98
  99        /*
 100         * Catch the cases where the clock framework hasn't been wired up
 101         * properly to support scaling.
 102         */
 103        if (unlikely(policy->min == policy->max)) {
 104                printk(KERN_ERR "cpufreq: clock framework rate rounding "
 105                       "not supported on this CPU.\n");
 106
 107                clk_put(cpuclk);
 108                return -EINVAL;
 109        }
 110
 111        printk(KERN_INFO "cpufreq: Frequencies - Minimum %u.%03u MHz, "
 112               "Maximum %u.%03u MHz.\n",
 113               policy->min / 1000, policy->min % 1000,
 114               policy->max / 1000, policy->max % 1000);
 115
 116        return 0;
 117}
 118
 119static int sh_cpufreq_verify(struct cpufreq_policy *policy)
 120{
 121        cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
 122                                     policy->cpuinfo.max_freq);
 123        return 0;
 124}
 125
 126static int sh_cpufreq_exit(struct cpufreq_policy *policy)
 127{
 128        clk_put(cpuclk);
 129        return 0;
 130}
 131
 132static struct cpufreq_driver sh_cpufreq_driver = {
 133        .owner          = THIS_MODULE,
 134        .name           = "sh",
 135        .init           = sh_cpufreq_cpu_init,
 136        .verify         = sh_cpufreq_verify,
 137        .target         = sh_cpufreq_target,
 138        .get            = sh_cpufreq_get,
 139        .exit           = sh_cpufreq_exit,
 140};
 141
 142static int __init sh_cpufreq_module_init(void)
 143{
 144        printk(KERN_INFO "cpufreq: SuperH CPU frequency driver.\n");
 145        return cpufreq_register_driver(&sh_cpufreq_driver);
 146}
 147
 148static void __exit sh_cpufreq_module_exit(void)
 149{
 150        cpufreq_unregister_driver(&sh_cpufreq_driver);
 151}
 152
 153module_init(sh_cpufreq_module_init);
 154module_exit(sh_cpufreq_module_exit);
 155
 156MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 157MODULE_DESCRIPTION("cpufreq driver for SuperH");
 158MODULE_LICENSE("GPL");
 159