Logo Search packages:      
Sourcecode: linux version File versions

cpufreq.c

/*
 * arch/sh/kernel/cpufreq.c
 *
 * cpufreq driver for the SuperH processors.
 *
 * Copyright (C) 2002 - 2007 Paul Mundt
 * Copyright (C) 2002 M. R. Brown
 *
 * Clock framework bits from arch/avr32/mach-at32ap/cpufreq.c
 *
 *   Copyright (C) 2004-2007 Atmel Corporation
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/types.h>
#include <linux/cpufreq.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/cpumask.h>
#include <linux/smp.h>
#include <linux/sched.h>      /* set_cpus_allowed() */
#include <linux/clk.h>

static struct clk *cpuclk;

static unsigned int sh_cpufreq_get(unsigned int cpu)
{
      return (clk_get_rate(cpuclk) + 500) / 1000;
}

/*
 * Here we notify other drivers of the proposed change and the final change.
 */
static int sh_cpufreq_target(struct cpufreq_policy *policy,
                       unsigned int target_freq,
                       unsigned int relation)
{
      unsigned int cpu = policy->cpu;
      cpumask_t cpus_allowed;
      struct cpufreq_freqs freqs;
      long freq;

      if (!cpu_online(cpu))
            return -ENODEV;

      cpus_allowed = current->cpus_allowed;
      set_cpus_allowed(current, cpumask_of_cpu(cpu));

      BUG_ON(smp_processor_id() != cpu);

      /* Convert target_freq from kHz to Hz */
      freq = clk_round_rate(cpuclk, target_freq * 1000);

      if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
            return -EINVAL;

      pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);

      freqs.cpu   = cpu;
      freqs.old   = sh_cpufreq_get(cpu);
      freqs.new   = (freq + 500) / 1000;
      freqs.flags = 0;

      cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
      set_cpus_allowed(current, cpus_allowed);
      clk_set_rate(cpuclk, freq);
      cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

      pr_debug("cpufreq: set frequency %lu Hz\n", freq);

      return 0;
}

static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
      if (!cpu_online(policy->cpu))
            return -ENODEV;

      cpuclk = clk_get(NULL, "cpu_clk");
      if (IS_ERR(cpuclk)) {
            printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
            return PTR_ERR(cpuclk);
      }

      /* cpuinfo and default policy values */
      policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
      policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
      policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;

      policy->cur       = sh_cpufreq_get(policy->cpu);
      policy->min       = policy->cpuinfo.min_freq;
      policy->max       = policy->cpuinfo.max_freq;


      /*
       * Catch the cases where the clock framework hasn't been wired up
       * properly to support scaling.
       */
      if (unlikely(policy->min == policy->max)) {
            printk(KERN_ERR "cpufreq: clock framework rate rounding "
                   "not supported on this CPU.\n");

            clk_put(cpuclk);
            return -EINVAL;
      }

      printk(KERN_INFO "cpufreq: Frequencies - Minimum %u.%03u MHz, "
             "Maximum %u.%03u MHz.\n",
             policy->min / 1000, policy->min % 1000,
             policy->max / 1000, policy->max % 1000);

      return 0;
}

static int sh_cpufreq_verify(struct cpufreq_policy *policy)
{
      cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
                             policy->cpuinfo.max_freq);
      return 0;
}

static int sh_cpufreq_exit(struct cpufreq_policy *policy)
{
      clk_put(cpuclk);
      return 0;
}

static struct cpufreq_driver sh_cpufreq_driver = {
      .owner            = THIS_MODULE,
      .name       = "sh",
      .init       = sh_cpufreq_cpu_init,
      .verify           = sh_cpufreq_verify,
      .target           = sh_cpufreq_target,
      .get        = sh_cpufreq_get,
      .exit       = sh_cpufreq_exit,
};

static int __init sh_cpufreq_module_init(void)
{
      printk(KERN_INFO "cpufreq: SuperH CPU frequency driver.\n");
      return cpufreq_register_driver(&sh_cpufreq_driver);
}

static void __exit sh_cpufreq_module_exit(void)
{
      cpufreq_unregister_driver(&sh_cpufreq_driver);
}

module_init(sh_cpufreq_module_init);
module_exit(sh_cpufreq_module_exit);

MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
MODULE_DESCRIPTION("cpufreq driver for SuperH");
MODULE_LICENSE("GPL");

Generated by  Doxygen 1.6.0   Back to index