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 static 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  */
  41 static 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
  81 static 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_cpu_limits(policy);
  91
  92         policy->min = (clk_round_rate(cpuclk, 1) + 500) / 1000;
  93         policy->max = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
  94
  95         cpufreq_verify_within_cpu_limits(policy);
  96         return 0;
  97 }
  98
  99 static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
 100 {
 101         unsigned int cpu = policy->cpu;
 102         struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 103         struct cpufreq_frequency_table *freq_table;
 104         struct device *dev;
 105
 106         dev = get_cpu_device(cpu);
 107
 108         cpuclk = clk_get(dev, "cpu_clk");
 109         if (IS_ERR(cpuclk)) {
 110                 dev_err(dev, "couldn't get CPU clk\n");
 111                 return PTR_ERR(cpuclk);
 112         }
 113
 114         freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
 115         if (freq_table) {
 116                 int result;
 117
 118                 result = cpufreq_table_validate_and_show(policy, freq_table);
 119                 if (result)
 120                         return result;
 121         } else {
 122                 dev_notice(dev, "no frequency table found, falling back "
 123                            "to rate rounding.\n");
 124
 125                 policy->min = policy->cpuinfo.min_freq =
 126                         (clk_round_rate(cpuclk, 1) + 500) / 1000;
 127                 policy->max = policy->cpuinfo.max_freq =
 128                         (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 129         }
 130
 131         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 132
 133         dev_info(dev, "CPU Frequencies - Minimum %u.%03u MHz, "
 134                "Maximum %u.%03u MHz.\n",
 135                policy->min / 1000, policy->min % 1000,
 136                policy->max / 1000, policy->max % 1000);
 137
 138         return 0;
 139 }
 140
 141 static int sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 142 {
 143         unsigned int cpu = policy->cpu;
 144         struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 145
 146         cpufreq_frequency_table_put_attr(cpu);
 147         clk_put(cpuclk);
 148
 149         return 0;
 150 }
 151
 152 static struct cpufreq_driver sh_cpufreq_driver = {
 153         .name           = "sh",
 154         .get            = sh_cpufreq_get,
 155         .target         = sh_cpufreq_target,
 156         .verify         = sh_cpufreq_verify,
 157         .init           = sh_cpufreq_cpu_init,
 158         .exit           = sh_cpufreq_cpu_exit,
 159         .attr           = cpufreq_generic_attr,
 160 };
 161
 162 static int __init sh_cpufreq_module_init(void)
 163 {
 164         pr_notice("SuperH CPU frequency driver.\n");
 165         return cpufreq_register_driver(&sh_cpufreq_driver);
 166 }
 167
 168 static void __exit sh_cpufreq_module_exit(void)
 169 {
 170         cpufreq_unregister_driver(&sh_cpufreq_driver);
 171 }
 172
 173 module_init(sh_cpufreq_module_init);
 174 module_exit(sh_cpufreq_module_exit);
 175
 176 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
 177 MODULE_DESCRIPTION("cpufreq driver for SuperH");
 178 MODULE_LICENSE("GPL");