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/sched.h>        /* set_cpus_allowed() */
  27 #include <linux/clk.h>
  28 #include <linux/percpu.h>
  29 #include <linux/sh_clk.h>
  30
  31 static DEFINE_PER_CPU(struct clk, sh_cpuclk);
  32
  33 struct cpufreq_target {
  34         struct cpufreq_policy   *policy;
  35         unsigned int            freq;
  36 };
  37
  38 static unsigned int sh_cpufreq_get(unsigned int cpu)
  39 {
  40         return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 500) / 1000;
  41 }
  42
  43 static 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  */
  81 static 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
  90 static int sh_cpufreq_verify(struct cpufreq_policy *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
 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         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                 int result;
 126
 127                 result = cpufreq_table_validate_and_show(policy, freq_table);
 128                 if (result)
 129                         return result;
 130         } else {
 131                 dev_notice(dev, "no frequency table found, falling back "
 132                            "to rate rounding.\n");
 133
 134                 policy->min = policy->cpuinfo.min_freq =
 135                         (clk_round_rate(cpuclk, 1) + 500) / 1000;
 136                 policy->max = policy->cpuinfo.max_freq =
 137                         (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 138         }
 139
 140         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 141
 142         dev_info(dev, "CPU Frequencies - Minimum %u.%03u MHz, "
 143                "Maximum %u.%03u MHz.\n",
 144                policy->min / 1000, policy->min % 1000,
 145                policy->max / 1000, policy->max % 1000);
 146
 147         return 0;
 148 }
 149
 150 static int sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 151 {
 152         unsigned int cpu = policy->cpu;
 153         struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 154
 155         clk_put(cpuclk);
 156
 157         return 0;
 158 }
 159
 160 static struct cpufreq_driver sh_cpufreq_driver = {
 161         .name           = "sh",
 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         .attr           = cpufreq_generic_attr,
 168 };
 169
 170 static int __init sh_cpufreq_module_init(void)
 171 {
 172         pr_notice("SuperH CPU frequency driver.\n");
 173         return cpufreq_register_driver(&sh_cpufreq_driver);
 174 }
 175
 176 static void __exit sh_cpufreq_module_exit(void)
 177 {
 178         cpufreq_unregister_driver(&sh_cpufreq_driver);
 179 }
 180
 181 module_init(sh_cpufreq_module_init);
 182 module_exit(sh_cpufreq_module_exit);
 183
 184 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 185 MODULE_DESCRIPTION("cpufreq driver for SuperH");
 186 MODULE_LICENSE("GPL");