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cpu-omap.c

/*
 *  linux/arch/arm/plat-omap/cpu-omap.c
 *
 *  CPU frequency scaling for OMAP
 *
 *  Copyright (C) 2005 Nokia Corporation
 *  Written by Tony Lindgren <tony@atomide.com>
 *
 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <plat/clock.h>
#include <asm/system.h>

#define VERY_HI_RATE    900000000

static struct cpufreq_frequency_table *freq_table;

#ifdef CONFIG_ARCH_OMAP1
#define MPU_CLK         "mpu"
#else
#define MPU_CLK         "virt_prcm_set"
#endif

static struct clk *mpu_clk;

/* TODO: Add support for SDRAM timing changes */

static int omap_verify_speed(struct cpufreq_policy *policy)
{
      if (freq_table)
            return cpufreq_frequency_table_verify(policy, freq_table);

      if (policy->cpu)
            return -EINVAL;

      cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
                             policy->cpuinfo.max_freq);

      policy->min = clk_round_rate(mpu_clk, policy->min * 1000) / 1000;
      policy->max = clk_round_rate(mpu_clk, policy->max * 1000) / 1000;
      cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
                             policy->cpuinfo.max_freq);
      return 0;
}

static unsigned int omap_getspeed(unsigned int cpu)
{
      unsigned long rate;

      if (cpu)
            return 0;

      rate = clk_get_rate(mpu_clk) / 1000;
      return rate;
}

static int omap_target(struct cpufreq_policy *policy,
                   unsigned int target_freq,
                   unsigned int relation)
{
      struct cpufreq_freqs freqs;
      int ret = 0;

      /* Ensure desired rate is within allowed range.  Some govenors
       * (ondemand) will just pass target_freq=0 to get the minimum. */
      if (target_freq < policy->min)
            target_freq = policy->min;
      if (target_freq > policy->max)
            target_freq = policy->max;

      freqs.old = omap_getspeed(0);
      freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
      freqs.cpu = 0;

      if (freqs.old == freqs.new)
            return ret;

      cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
#ifdef CONFIG_CPU_FREQ_DEBUG
      printk(KERN_DEBUG "cpufreq-omap: transition: %u --> %u\n",
             freqs.old, freqs.new);
#endif
      ret = clk_set_rate(mpu_clk, freqs.new * 1000);
      cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

      return ret;
}

static int __init omap_cpu_init(struct cpufreq_policy *policy)
{
      int result = 0;

      mpu_clk = clk_get(NULL, MPU_CLK);
      if (IS_ERR(mpu_clk))
            return PTR_ERR(mpu_clk);

      if (policy->cpu != 0)
            return -EINVAL;

      policy->cur = policy->min = policy->max = omap_getspeed(0);

      clk_init_cpufreq_table(&freq_table);
      if (freq_table) {
            result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
            if (!result)
                  cpufreq_frequency_table_get_attr(freq_table,
                                          policy->cpu);
      } else {
            policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
            policy->cpuinfo.max_freq = clk_round_rate(mpu_clk,
                                          VERY_HI_RATE) / 1000;
      }

      /* FIXME: what's the actual transition time? */
      policy->cpuinfo.transition_latency = 300 * 1000;

      return 0;
}

static int omap_cpu_exit(struct cpufreq_policy *policy)
{
      clk_exit_cpufreq_table(&freq_table);
      clk_put(mpu_clk);
      return 0;
}

static struct freq_attr *omap_cpufreq_attr[] = {
      &cpufreq_freq_attr_scaling_available_freqs,
      NULL,
};

static struct cpufreq_driver omap_driver = {
      .flags            = CPUFREQ_STICKY,
      .verify           = omap_verify_speed,
      .target           = omap_target,
      .get        = omap_getspeed,
      .init       = omap_cpu_init,
      .exit       = omap_cpu_exit,
      .name       = "omap",
      .attr       = omap_cpufreq_attr,
};

static int __init omap_cpufreq_init(void)
{
      return cpufreq_register_driver(&omap_driver);
}

arch_initcall(omap_cpufreq_init);

/*
 * if ever we want to remove this, upon cleanup call:
 *
 * cpufreq_unregister_driver()
 * cpufreq_frequency_table_put_attr()
 */


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