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/io.h>
  27 #include <linux/clk.h>
  28 #include <asm/processor.h>
  29 #include <asm/watchdog.h>
  30 #include <asm/freq.h>
  31 #include <asm/clock.h>
  32
  33 static struct clk *cpuclk;
  34
  35 static unsigned int sh_cpufreq_get(unsigned int cpu)
  36 {
  37         return (clk_get_rate(cpuclk) + 500) / 1000;
  38 }
  39
  40 /*
  41  * Here we notify other drivers of the proposed change and the final change.
  42  */
  43 static int sh_cpufreq_target(struct cpufreq_policy *policy,
  44                              unsigned int target_freq,
  45                              unsigned int relation)
  46 {
  47         unsigned int cpu = policy->cpu;
  48         cpumask_t cpus_allowed;
  49         struct cpufreq_freqs freqs;
  50         long freq;
  51
  52         if (!cpu_online(cpu))
  53                 return -ENODEV;
  54
  55         cpus_allowed = current->cpus_allowed;
  56         set_cpus_allowed(current, cpumask_of_cpu(cpu));
  57
  58         BUG_ON(smp_processor_id() != cpu);
  59
  60         /* Convert target_freq from kHz to Hz */
  61         freq = clk_round_rate(cpuclk, target_freq * 1000);
  62
  63         if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
  64                 return -EINVAL;
  65
  66         pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
  67
  68         freqs.cpu       = cpu;
  69         freqs.old       = sh_cpufreq_get(cpu);
  70         freqs.new       = (freq + 500) / 1000;
  71         freqs.flags     = 0;
  72
  73         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  74         set_cpus_allowed(current, cpus_allowed);
  75         clk_set_rate(cpuclk, freq);
  76         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  77
  78         pr_debug("cpufreq: set frequency %lu Hz\n", freq);
  79
  80         return 0;
  81 }
  82
  83 static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
  84 {
  85         printk(KERN_INFO "cpufreq: SuperH CPU frequency driver.\n");
  86
  87         if (!cpu_online(policy->cpu))
  88                 return -ENODEV;
  89
  90         cpuclk = clk_get(NULL, "cpu_clk");
  91         if (IS_ERR(cpuclk)) {
  92                 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
  93                 return PTR_ERR(cpuclk);
  94         }
  95
  96         /* cpuinfo and default policy values */
  97         policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
  98         policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
  99         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 100
 101         policy->governor        = CPUFREQ_DEFAULT_GOVERNOR;
 102         policy->cur             = sh_cpufreq_get(policy->cpu);
 103         policy->min             = policy->cpuinfo.min_freq;
 104         policy->max             = policy->cpuinfo.max_freq;
 105
 106
 107         /*
 108          * Catch the cases where the clock framework hasn't been wired up
 109          * properly to support scaling.
 110          */
 111         if (unlikely(policy->min == policy->max)) {
 112                 printk(KERN_ERR "cpufreq: clock framework rate rounding "
 113                        "not supported on this CPU.\n");
 114
 115                 clk_put(cpuclk);
 116                 return -EINVAL;
 117         }
 118
 119         printk(KERN_INFO "cpufreq: Frequencies - Minimum %u.%03u MHz, "
 120                "Maximum %u.%03u MHz.\n",
 121                policy->min / 1000, policy->min % 1000,
 122                policy->max / 1000, policy->max % 1000);
 123
 124         return 0;
 125 }
 126
 127 static int sh_cpufreq_verify(struct cpufreq_policy *policy)
 128 {
 129         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
 130                                      policy->cpuinfo.max_freq);
 131         return 0;
 132 }
 133
 134 static int sh_cpufreq_exit(struct cpufreq_policy *policy)
 135 {
 136         clk_put(cpuclk);
 137         return 0;
 138 }
 139
 140 static struct cpufreq_driver sh_cpufreq_driver = {
 141         .owner          = THIS_MODULE,
 142         .name           = "sh",
 143         .init           = sh_cpufreq_cpu_init,
 144         .verify         = sh_cpufreq_verify,
 145         .target         = sh_cpufreq_target,
 146         .get            = sh_cpufreq_get,
 147         .exit           = sh_cpufreq_exit,
 148 };
 149
 150 static int __init sh_cpufreq_module_init(void)
 151 {
 152         return cpufreq_register_driver(&sh_cpufreq_driver);
 153 }
 154
 155 static void __exit sh_cpufreq_module_exit(void)
 156 {
 157         cpufreq_unregister_driver(&sh_cpufreq_driver);
 158 }
 159
 160 module_init(sh_cpufreq_module_init);
 161 module_exit(sh_cpufreq_module_exit);
 162
 163 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 164 MODULE_DESCRIPTION("cpufreq driver for SuperH");
 165 MODULE_LICENSE("GPL");