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
  28 static struct clk *cpuclk;
  29
  30 static 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  */
  38 static 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
  78 static 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
 119 static 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
 126 static int sh_cpufreq_exit(struct cpufreq_policy *policy)
 127 {
 128         clk_put(cpuclk);
 129         return 0;
 130 }
 131
 132 static 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
 142 static 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
 148 static void __exit sh_cpufreq_module_exit(void)
 149 {
 150         cpufreq_unregister_driver(&sh_cpufreq_driver);
 151 }
 152
 153 module_init(sh_cpufreq_module_init);
 154 module_exit(sh_cpufreq_module_exit);
 155
 156 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 157 MODULE_DESCRIPTION("cpufreq driver for SuperH");
 158 MODULE_LICENSE("GPL");