LXR linux/drivers/cpufreq/sh-cpufreq.c

   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/clk.h>
  27#include <linux/percpu.h>
  28#include <linux/sh_clk.h>
  29
  30static DEFINE_PER_CPU(struct clk, sh_cpuclk);
  31
  32struct cpufreq_target {
  33        struct cpufreq_policy   *policy;
  34        unsigned int            freq;
  35};
  36
  37static unsigned int sh_cpufreq_get(unsigned int cpu)
  38{
  39        return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 500) / 1000;
  40}
  41
  42static long __sh_cpufreq_target(void *arg)
  43{
  44        struct cpufreq_target *target = arg;
  45        struct cpufreq_policy *policy = target->policy;
  46        int cpu = policy->cpu;
  47        struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
  48        struct cpufreq_freqs freqs;
  49        struct device *dev;
  50        long freq;
  51
  52        if (smp_processor_id() != cpu)
  53                return -ENODEV;
  54
  55        dev = get_cpu_device(cpu);
  56
  57        /* Convert target_freq from kHz to Hz */
  58        freq = clk_round_rate(cpuclk, target->freq * 1000);
  59
  60        if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
  61                return -EINVAL;
  62
  63        dev_dbg(dev, "requested frequency %u Hz\n", target->freq * 1000);
  64
  65        freqs.old       = sh_cpufreq_get(cpu);
  66        freqs.new       = (freq + 500) / 1000;
  67        freqs.flags     = 0;
  68
  69        cpufreq_freq_transition_begin(target->policy, &freqs);
  70        clk_set_rate(cpuclk, freq);
  71        cpufreq_freq_transition_end(target->policy, &freqs, 0);
  72
  73        dev_dbg(dev, "set frequency %lu Hz\n", freq);
  74        return 0;
  75}
  76
  77/*
  78 * Here we notify other drivers of the proposed change and the final change.
  79 */
  80static int sh_cpufreq_target(struct cpufreq_policy *policy,
  81                             unsigned int target_freq,
  82                             unsigned int relation)
  83{
  84        struct cpufreq_target data = { .policy = policy, .freq = target_freq };
  85
  86        return work_on_cpu(policy->cpu, __sh_cpufreq_target, &data);
  87}
  88
  89static int sh_cpufreq_verify(struct cpufreq_policy_data *policy)
  90{
  91        struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);
  92        struct cpufreq_frequency_table *freq_table;
  93
  94        freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
  95        if (freq_table)
  96                return cpufreq_frequency_table_verify(policy, freq_table);
  97
  98        cpufreq_verify_within_cpu_limits(policy);
  99
 100        policy->min = (clk_round_rate(cpuclk, 1) + 500) / 1000;
 101        policy->max = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 102
 103        cpufreq_verify_within_cpu_limits(policy);
 104        return 0;
 105}
 106
 107static 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        dev = get_cpu_device(cpu);
 115
 116        cpuclk = clk_get(dev, "cpu_clk");
 117        if (IS_ERR(cpuclk)) {
 118                dev_err(dev, "couldn't get CPU clk\n");
 119                return PTR_ERR(cpuclk);
 120        }
 121
 122        freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
 123        if (freq_table) {
 124                policy->freq_table = freq_table;
 125        } else {
 126                dev_notice(dev, "no frequency table found, falling back "
 127                           "to rate rounding.\n");
 128
 129                policy->min = policy->cpuinfo.min_freq =
 130                        (clk_round_rate(cpuclk, 1) + 500) / 1000;
 131                policy->max = policy->cpuinfo.max_freq =
 132                        (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 133        }
 134
 135        return 0;
 136}
 137
 138static int sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 139{
 140        unsigned int cpu = policy->cpu;
 141        struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 142
 143        clk_put(cpuclk);
 144
 145        return 0;
 146}
 147
 148static struct cpufreq_driver sh_cpufreq_driver = {
 149        .name           = "sh",
 150        .flags          = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
 151        .get            = sh_cpufreq_get,
 152        .target         = sh_cpufreq_target,
 153        .verify         = sh_cpufreq_verify,
 154        .init           = sh_cpufreq_cpu_init,
 155        .exit           = sh_cpufreq_cpu_exit,
 156        .attr           = cpufreq_generic_attr,
 157};
 158
 159static int __init sh_cpufreq_module_init(void)
 160{
 161        pr_notice("SuperH CPU frequency driver.\n");
 162        return cpufreq_register_driver(&sh_cpufreq_driver);
 163}
 164
 165static void __exit sh_cpufreq_module_exit(void)
 166{
 167        cpufreq_unregister_driver(&sh_cpufreq_driver);
 168}
 169
 170module_init(sh_cpufreq_module_init);
 171module_exit(sh_cpufreq_module_exit);
 172
 173MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 174MODULE_DESCRIPTION("cpufreq driver for SuperH");
 175MODULE_LICENSE("GPL");
 176