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
  33struct cpufreq_target {
  34        struct cpufreq_policy   *policy;
  35        unsigned int            freq;
  36};
  37
  38static unsigned int sh_cpufreq_get(unsigned int cpu)
  39{
  40        return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 500) / 1000;
  41}
  42
  43static long __sh_cpufreq_target(void *arg)
  44{
  45        struct cpufreq_target *target = arg;
  46        struct cpufreq_policy *policy = target->policy;
  47        int cpu = policy->cpu;
  48        struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
  49        struct cpufreq_freqs freqs;
  50        struct device *dev;
  51        long freq;
  52
  53        if (smp_processor_id() != cpu)
  54                return -ENODEV;
  55
  56        dev = get_cpu_device(cpu);
  57
  58        /* Convert target_freq from kHz to Hz */
  59        freq = clk_round_rate(cpuclk, target->freq * 1000);
  60
  61        if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
  62                return -EINVAL;
  63
  64        dev_dbg(dev, "requested frequency %u Hz\n", target->freq * 1000);
  65
  66        freqs.old       = sh_cpufreq_get(cpu);
  67        freqs.new       = (freq + 500) / 1000;
  68        freqs.flags     = 0;
  69
  70        cpufreq_freq_transition_begin(target->policy, &freqs);
  71        clk_set_rate(cpuclk, freq);
  72        cpufreq_freq_transition_end(target->policy, &freqs, 0);
  73
  74        dev_dbg(dev, "set frequency %lu Hz\n", freq);
  75        return 0;
  76}
  77
  78/*
  79 * Here we notify other drivers of the proposed change and the final change.
  80 */
  81static int sh_cpufreq_target(struct cpufreq_policy *policy,
  82                             unsigned int target_freq,
  83                             unsigned int relation)
  84{
  85        struct cpufreq_target data = { .policy = policy, .freq = target_freq };
  86
  87        return work_on_cpu(policy->cpu, __sh_cpufreq_target, &data);
  88}
  89
  90static int sh_cpufreq_verify(struct cpufreq_policy_data *policy)
  91{
  92        struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);
  93        struct cpufreq_frequency_table *freq_table;
  94
  95        freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
  96        if (freq_table)
  97                return cpufreq_frequency_table_verify(policy, freq_table);
  98
  99        cpufreq_verify_within_cpu_limits(policy);
 100
 101        policy->min = (clk_round_rate(cpuclk, 1) + 500) / 1000;
 102        policy->max = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 103
 104        cpufreq_verify_within_cpu_limits(policy);
 105        return 0;
 106}
 107
 108static 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        dev = get_cpu_device(cpu);
 116
 117        cpuclk = clk_get(dev, "cpu_clk");
 118        if (IS_ERR(cpuclk)) {
 119                dev_err(dev, "couldn't get CPU clk\n");
 120                return PTR_ERR(cpuclk);
 121        }
 122
 123        freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
 124        if (freq_table) {
 125                policy->freq_table = freq_table;
 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        return 0;
 137}
 138
 139static int sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 140{
 141        unsigned int cpu = policy->cpu;
 142        struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 143
 144        clk_put(cpuclk);
 145
 146        return 0;
 147}
 148
 149static void sh_cpufreq_cpu_ready(struct cpufreq_policy *policy)
 150{
 151        struct device *dev = get_cpu_device(policy->cpu);
 152
 153        dev_info(dev, "CPU Frequencies - Minimum %u.%03u MHz, "
 154               "Maximum %u.%03u MHz.\n",
 155               policy->min / 1000, policy->min % 1000,
 156               policy->max / 1000, policy->max % 1000);
 157}
 158
 159static struct cpufreq_driver sh_cpufreq_driver = {
 160        .name           = "sh",
 161        .flags          = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
 162        .get            = sh_cpufreq_get,
 163        .target         = sh_cpufreq_target,
 164        .verify         = sh_cpufreq_verify,
 165        .init           = sh_cpufreq_cpu_init,
 166        .exit           = sh_cpufreq_cpu_exit,
 167        .ready          = sh_cpufreq_cpu_ready,
 168        .attr           = cpufreq_generic_attr,
 169};
 170
 171static int __init sh_cpufreq_module_init(void)
 172{
 173        pr_notice("SuperH CPU frequency driver.\n");
 174        return cpufreq_register_driver(&sh_cpufreq_driver);
 175}
 176
 177static void __exit sh_cpufreq_module_exit(void)
 178{
 179        cpufreq_unregister_driver(&sh_cpufreq_driver);
 180}
 181
 182module_init(sh_cpufreq_module_init);
 183module_exit(sh_cpufreq_module_exit);
 184
 185MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 186MODULE_DESCRIPTION("cpufreq driver for SuperH");
 187MODULE_LICENSE("GPL");
 188