linux/drivers/cpufreq/sh-cpufreq.c
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   1/*
   2 * cpufreq driver for the SuperH processors.
   3 *
   4 * Copyright (C) 2002 - 2012 Paul Mundt
   5 * Copyright (C) 2002 M. R. Brown
   6 *
   7 * Clock framework bits from arch/avr32/mach-at32ap/cpufreq.c
   8 *
   9 *   Copyright (C) 2004-2007 Atmel Corporation
  10 *
  11 * This file is subject to the terms and conditions of the GNU General Public
  12 * License.  See the file "COPYING" in the main directory of this archive
  13 * for more details.
  14 */
  15#define pr_fmt(fmt) "cpufreq: " fmt
  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/cpu.h>
  25#include <linux/smp.h>
  26#include <linux/sched.h>        /* set_cpus_allowed() */
  27#include <linux/clk.h>
  28#include <linux/percpu.h>
  29#include <linux/sh_clk.h>
  30
  31static DEFINE_PER_CPU(struct clk, sh_cpuclk);
  32
  33static unsigned int sh_cpufreq_get(unsigned int cpu)
  34{
  35        return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 500) / 1000;
  36}
  37
  38/*
  39 * Here we notify other drivers of the proposed change and the final change.
  40 */
  41static int sh_cpufreq_target(struct cpufreq_policy *policy,
  42                             unsigned int target_freq,
  43                             unsigned int relation)
  44{
  45        unsigned int cpu = policy->cpu;
  46        struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
  47        cpumask_t cpus_allowed;
  48        struct cpufreq_freqs freqs;
  49        struct device *dev;
  50        long freq;
  51
  52        cpus_allowed = current->cpus_allowed;
  53        set_cpus_allowed_ptr(current, cpumask_of(cpu));
  54
  55        BUG_ON(smp_processor_id() != cpu);
  56
  57        dev = get_cpu_device(cpu);
  58
  59        /* Convert target_freq from kHz to Hz */
  60        freq = clk_round_rate(cpuclk, target_freq * 1000);
  61
  62        if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
  63                return -EINVAL;
  64
  65        dev_dbg(dev, "requested frequency %u Hz\n", target_freq * 1000);
  66
  67        freqs.old       = sh_cpufreq_get(cpu);
  68        freqs.new       = (freq + 500) / 1000;
  69        freqs.flags     = 0;
  70
  71        cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  72        set_cpus_allowed_ptr(current, &cpus_allowed);
  73        clk_set_rate(cpuclk, freq);
  74        cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
  75
  76        dev_dbg(dev, "set frequency %lu Hz\n", freq);
  77
  78        return 0;
  79}
  80
  81static int sh_cpufreq_verify(struct cpufreq_policy *policy)
  82{
  83        struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);
  84        struct cpufreq_frequency_table *freq_table;
  85
  86        freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
  87        if (freq_table)
  88                return cpufreq_frequency_table_verify(policy, freq_table);
  89
  90        cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  91                                     policy->cpuinfo.max_freq);
  92
  93        policy->min = (clk_round_rate(cpuclk, 1) + 500) / 1000;
  94        policy->max = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
  95
  96        cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  97                                     policy->cpuinfo.max_freq);
  98
  99        return 0;
 100}
 101
 102static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
 103{
 104        unsigned int cpu = policy->cpu;
 105        struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 106        struct cpufreq_frequency_table *freq_table;
 107        struct device *dev;
 108
 109        dev = get_cpu_device(cpu);
 110
 111        cpuclk = clk_get(dev, "cpu_clk");
 112        if (IS_ERR(cpuclk)) {
 113                dev_err(dev, "couldn't get CPU clk\n");
 114                return PTR_ERR(cpuclk);
 115        }
 116
 117        policy->cur = sh_cpufreq_get(cpu);
 118
 119        freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
 120        if (freq_table) {
 121                int result;
 122
 123                result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 124                if (!result)
 125                        cpufreq_frequency_table_get_attr(freq_table, cpu);
 126        } else {
 127                dev_notice(dev, "no frequency table found, falling back "
 128                           "to rate rounding.\n");
 129
 130                policy->min = policy->cpuinfo.min_freq =
 131                        (clk_round_rate(cpuclk, 1) + 500) / 1000;
 132                policy->max = policy->cpuinfo.max_freq =
 133                        (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 134        }
 135
 136        policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 137
 138        dev_info(dev, "CPU Frequencies - Minimum %u.%03u MHz, "
 139               "Maximum %u.%03u MHz.\n",
 140               policy->min / 1000, policy->min % 1000,
 141               policy->max / 1000, policy->max % 1000);
 142
 143        return 0;
 144}
 145
 146static int sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 147{
 148        unsigned int cpu = policy->cpu;
 149        struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 150
 151        cpufreq_frequency_table_put_attr(cpu);
 152        clk_put(cpuclk);
 153
 154        return 0;
 155}
 156
 157static struct freq_attr *sh_freq_attr[] = {
 158        &cpufreq_freq_attr_scaling_available_freqs,
 159        NULL,
 160};
 161
 162static struct cpufreq_driver sh_cpufreq_driver = {
 163        .owner          = THIS_MODULE,
 164        .name           = "sh",
 165        .get            = sh_cpufreq_get,
 166        .target         = sh_cpufreq_target,
 167        .verify         = sh_cpufreq_verify,
 168        .init           = sh_cpufreq_cpu_init,
 169        .exit           = sh_cpufreq_cpu_exit,
 170        .attr           = sh_freq_attr,
 171};
 172
 173static int __init sh_cpufreq_module_init(void)
 174{
 175        pr_notice("SuperH CPU frequency driver.\n");
 176        return cpufreq_register_driver(&sh_cpufreq_driver);
 177}
 178
 179static void __exit sh_cpufreq_module_exit(void)
 180{
 181        cpufreq_unregister_driver(&sh_cpufreq_driver);
 182}
 183
 184module_init(sh_cpufreq_module_init);
 185module_exit(sh_cpufreq_module_exit);
 186
 187MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 188MODULE_DESCRIPTION("cpufreq driver for SuperH");
 189MODULE_LICENSE("GPL");
 190
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