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
  30 static DEFINE_PER_CPU(struct clk, sh_cpuclk);
  31
  32 struct cpufreq_target {
  33         struct cpufreq_policy   *policy;
  34         unsigned int            freq;
  35 };
  36
  37 static unsigned int sh_cpufreq_get(unsigned int cpu)
  38 {
  39         return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 500) / 1000;
  40 }
  41
  42 static 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  */
  80 static 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
  89 static 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
 107 static 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
 138 static void 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
 146 static struct cpufreq_driver sh_cpufreq_driver = {
 147         .name           = "sh",
 148         .flags          = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
 149         .get            = sh_cpufreq_get,
 150         .target         = sh_cpufreq_target,
 151         .verify         = sh_cpufreq_verify,
 152         .init           = sh_cpufreq_cpu_init,
 153         .exit           = sh_cpufreq_cpu_exit,
 154         .attr           = cpufreq_generic_attr,
 155 };
 156
 157 static int __init sh_cpufreq_module_init(void)
 158 {
 159         pr_notice("SuperH CPU frequency driver.\n");
 160         return cpufreq_register_driver(&sh_cpufreq_driver);
 161 }
 162
 163 static void __exit sh_cpufreq_module_exit(void)
 164 {
 165         cpufreq_unregister_driver(&sh_cpufreq_driver);
 166 }
 167
 168 module_init(sh_cpufreq_module_init);
 169 module_exit(sh_cpufreq_module_exit);
 170
 171 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 172 MODULE_DESCRIPTION("cpufreq driver for SuperH");
 173 MODULE_LICENSE("GPL");