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.cpu       = cpu;
  73         freqs.old       = sh_cpufreq_get(cpu);
  74         freqs.new       = (freq + 500) / 1000;
  75         freqs.flags     = 0;
  76
  77         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  78         set_cpus_allowed_ptr(current, &cpus_allowed);
  79         clk_set_rate(cpuclk, freq);
  80         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  81
  82         dev_dbg(dev, "set frequency %lu Hz\n", freq);
  83
  84         return 0;
  85 }
  86
  87 static int sh_cpufreq_verify(struct cpufreq_policy *policy)
  88 {
  89         struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);
  90         struct cpufreq_frequency_table *freq_table;
  91
  92         freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
  93         if (freq_table)
  94                 return cpufreq_frequency_table_verify(policy, freq_table);
  95
  96         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  97                                      policy->cpuinfo.max_freq);
  98
  99         policy->min = (clk_round_rate(cpuclk, 1) + 500) / 1000;
 100         policy->max = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 101
 102         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
 103                                      policy->cpuinfo.max_freq);
 104
 105         return 0;
 106 }
 107
 108 static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
 109 {
 110         unsigned int cpu = policy->cpu;
 111         struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 112         struct cpufreq_frequency_table *freq_table;
 113         struct device *dev;
 114
 115         if (!cpu_online(cpu))
 116                 return -ENODEV;
 117
 118         dev = get_cpu_device(cpu);
 119
 120         cpuclk = clk_get(dev, "cpu_clk");
 121         if (IS_ERR(cpuclk)) {
 122                 dev_err(dev, "couldn't get CPU clk\n");
 123                 return PTR_ERR(cpuclk);
 124         }
 125
 126         policy->cur = policy->min = policy->max = sh_cpufreq_get(cpu);
 127
 128         freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
 129         if (freq_table) {
 130                 int result;
 131
 132                 result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 133                 if (!result)
 134                         cpufreq_frequency_table_get_attr(freq_table, cpu);
 135         } else {
 136                 dev_notice(dev, "no frequency table found, falling back "
 137                            "to rate rounding.\n");
 138
 139                 policy->cpuinfo.min_freq =
 140                         (clk_round_rate(cpuclk, 1) + 500) / 1000;
 141                 policy->cpuinfo.max_freq =
 142                         (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 143         }
 144
 145         policy->min = policy->cpuinfo.min_freq;
 146         policy->max = policy->cpuinfo.max_freq;
 147
 148         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 149
 150         dev_info(dev, "CPU Frequencies - Minimum %u.%03u MHz, "
 151                "Maximum %u.%03u MHz.\n",
 152                policy->min / 1000, policy->min % 1000,
 153                policy->max / 1000, policy->max % 1000);
 154
 155         return 0;
 156 }
 157
 158 static int sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 159 {
 160         unsigned int cpu = policy->cpu;
 161         struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 162
 163         cpufreq_frequency_table_put_attr(cpu);
 164         clk_put(cpuclk);
 165
 166         return 0;
 167 }
 168
 169 static struct freq_attr *sh_freq_attr[] = {
 170         &cpufreq_freq_attr_scaling_available_freqs,
 171         NULL,
 172 };
 173
 174 static struct cpufreq_driver sh_cpufreq_driver = {
 175         .owner          = THIS_MODULE,
 176         .name           = "sh",
 177         .get            = sh_cpufreq_get,
 178         .target         = sh_cpufreq_target,
 179         .verify         = sh_cpufreq_verify,
 180         .init           = sh_cpufreq_cpu_init,
 181         .exit           = sh_cpufreq_cpu_exit,
 182         .attr           = sh_freq_attr,
 183 };
 184
 185 static int __init sh_cpufreq_module_init(void)
 186 {
 187         pr_notice("SuperH CPU frequency driver.\n");
 188         return cpufreq_register_driver(&sh_cpufreq_driver);
 189 }
 190
 191 static void __exit sh_cpufreq_module_exit(void)
 192 {
 193         cpufreq_unregister_driver(&sh_cpufreq_driver);
 194 }
 195
 196 module_init(sh_cpufreq_module_init);
 197 module_exit(sh_cpufreq_module_exit);
 198
 199 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 200 MODULE_DESCRIPTION("cpufreq driver for SuperH");
 201 MODULE_LICENSE("GPL");