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 - 2012 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 #define pr_fmt(fmt) "cpufreq: " fmt
  18
  19 #include <linux/types.h>
  20 #include <linux/cpufreq.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/init.h>
  24 #include <linux/err.h>
  25 #include <linux/cpumask.h>
  26 #include <linux/cpu.h>
  27 #include <linux/smp.h>
  28 #include <linux/sched.h>        /* set_cpus_allowed() */
  29 #include <linux/clk.h>
  30 #include <linux/percpu.h>
  31 #include <linux/sh_clk.h>
  32
  33 static DEFINE_PER_CPU(struct clk, sh_cpuclk);
  34
  35 static unsigned int sh_cpufreq_get(unsigned int cpu)
  36 {
  37         return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 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         struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
  49         cpumask_t cpus_allowed;
  50         struct cpufreq_freqs freqs;
  51         struct device *dev;
  52         long freq;
  53
  54         if (!cpu_online(cpu))
  55                 return -ENODEV;
  56
  57         cpus_allowed = current->cpus_allowed;
  58         set_cpus_allowed_ptr(current, cpumask_of(cpu));
  59
  60         BUG_ON(smp_processor_id() != cpu);
  61
  62         dev = get_cpu_device(cpu);
  63
  64         /* Convert target_freq from kHz to Hz */
  65         freq = clk_round_rate(cpuclk, target_freq * 1000);
  66
  67         if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
  68                 return -EINVAL;
  69
  70         dev_dbg(dev, "requested frequency %u Hz\n", target_freq * 1000);
  71
  72         freqs.old       = sh_cpufreq_get(cpu);
  73         freqs.new       = (freq + 500) / 1000;
  74         freqs.flags     = 0;
  75
  76         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  77         set_cpus_allowed_ptr(current, &cpus_allowed);
  78         clk_set_rate(cpuclk, freq);
  79         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
  80
  81         dev_dbg(dev, "set frequency %lu Hz\n", freq);
  82
  83         return 0;
  84 }
  85
  86 static int sh_cpufreq_verify(struct cpufreq_policy *policy)
  87 {
  88         struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);
  89         struct cpufreq_frequency_table *freq_table;
  90
  91         freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
  92         if (freq_table)
  93                 return cpufreq_frequency_table_verify(policy, freq_table);
  94
  95         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  96                                      policy->cpuinfo.max_freq);
  97
  98         policy->min = (clk_round_rate(cpuclk, 1) + 500) / 1000;
  99         policy->max = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 100
 101         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
 102                                      policy->cpuinfo.max_freq);
 103
 104         return 0;
 105 }
 106
 107 static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
 108 {
 109         unsigned int cpu = policy->cpu;
 110         struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 111         struct cpufreq_frequency_table *freq_table;
 112         struct device *dev;
 113
 114         if (!cpu_online(cpu))
 115                 return -ENODEV;
 116
 117         dev = get_cpu_device(cpu);
 118
 119         cpuclk = clk_get(dev, "cpu_clk");
 120         if (IS_ERR(cpuclk)) {
 121                 dev_err(dev, "couldn't get CPU clk\n");
 122                 return PTR_ERR(cpuclk);
 123         }
 124
 125         policy->cur = policy->min = policy->max = sh_cpufreq_get(cpu);
 126
 127         freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
 128         if (freq_table) {
 129                 int result;
 130
 131                 result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 132                 if (!result)
 133                         cpufreq_frequency_table_get_attr(freq_table, cpu);
 134         } else {
 135                 dev_notice(dev, "no frequency table found, falling back "
 136                            "to rate rounding.\n");
 137
 138                 policy->cpuinfo.min_freq =
 139                         (clk_round_rate(cpuclk, 1) + 500) / 1000;
 140                 policy->cpuinfo.max_freq =
 141                         (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 142         }
 143
 144         policy->min = policy->cpuinfo.min_freq;
 145         policy->max = policy->cpuinfo.max_freq;
 146
 147         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 148
 149         dev_info(dev, "CPU Frequencies - Minimum %u.%03u MHz, "
 150                "Maximum %u.%03u MHz.\n",
 151                policy->min / 1000, policy->min % 1000,
 152                policy->max / 1000, policy->max % 1000);
 153
 154         return 0;
 155 }
 156
 157 static int sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 158 {
 159         unsigned int cpu = policy->cpu;
 160         struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 161
 162         cpufreq_frequency_table_put_attr(cpu);
 163         clk_put(cpuclk);
 164
 165         return 0;
 166 }
 167
 168 static struct freq_attr *sh_freq_attr[] = {
 169         &cpufreq_freq_attr_scaling_available_freqs,
 170         NULL,
 171 };
 172
 173 static struct cpufreq_driver sh_cpufreq_driver = {
 174         .owner          = THIS_MODULE,
 175         .name           = "sh",
 176         .get            = sh_cpufreq_get,
 177         .target         = sh_cpufreq_target,
 178         .verify         = sh_cpufreq_verify,
 179         .init           = sh_cpufreq_cpu_init,
 180         .exit           = sh_cpufreq_cpu_exit,
 181         .attr           = sh_freq_attr,
 182 };
 183
 184 static int __init sh_cpufreq_module_init(void)
 185 {
 186         pr_notice("SuperH CPU frequency driver.\n");
 187         return cpufreq_register_driver(&sh_cpufreq_driver);
 188 }
 189
 190 static void __exit sh_cpufreq_module_exit(void)
 191 {
 192         cpufreq_unregister_driver(&sh_cpufreq_driver);
 193 }
 194
 195 module_init(sh_cpufreq_module_init);
 196 module_exit(sh_cpufreq_module_exit);
 197
 198 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 199 MODULE_DESCRIPTION("cpufreq driver for SuperH");
 200 MODULE_LICENSE("GPL");