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cpufreq.c

/*
 * CPU frequency scaling for DaVinci
 *
 * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
 *
 * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
 *
 *  Copyright (C) 2005 Nokia Corporation
 *  Written by Tony Lindgren <tony@atomide.com>
 *
 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
 *
 * Copyright (C) 2007-2008 Texas Instruments, Inc.
 * Updated to support OMAP3
 * Rajendra Nayak <rnayak@ti.com>
 *
 * 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/cpufreq.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/platform_device.h>

#include <mach/hardware.h>
#include <mach/cpufreq.h>
#include <mach/common.h>

#include "clock.h"

00034 struct davinci_cpufreq {
      struct device *dev;
      struct clk *armclk;
      struct clk *asyncclk;
      unsigned long asyncrate;
};
static struct davinci_cpufreq cpufreq;

static int davinci_verify_speed(struct cpufreq_policy *policy)
{
      struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
      struct cpufreq_frequency_table *freq_table = pdata->freq_table;
      struct clk *armclk = cpufreq.armclk;

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

static unsigned int davinci_getspeed(unsigned int cpu)
{
      if (cpu)
            return 0;

      return clk_get_rate(cpufreq.armclk) / 1000;
}

static int davinci_target(struct cpufreq_policy *policy,
                        unsigned int target_freq, unsigned int relation)
{
      int ret = 0;
      unsigned int idx;
      struct cpufreq_freqs freqs;
      struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
      struct clk *armclk = cpufreq.armclk;

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

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

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

      cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER,
                  dev_driver_string(cpufreq.dev),
                  "transition: %u --> %u\n", freqs.old, freqs.new);

      ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
                                    freqs.new, relation, &idx);
      if (ret)
            return -EINVAL;

      cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

      /* if moving to higher frequency, up the voltage beforehand */
      if (pdata->set_voltage && freqs.new > freqs.old) {
            ret = pdata->set_voltage(idx);
            if (ret)
                  goto out;
      }

      ret = clk_set_rate(armclk, idx);
      if (ret)
            goto out;

      if (cpufreq.asyncclk) {
            ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
            if (ret)
                  goto out;
      }

      /* if moving to lower freq, lower the voltage after lowering freq */
      if (pdata->set_voltage && freqs.new < freqs.old)
            pdata->set_voltage(idx);

out:
      cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

      return ret;
}

static int __init davinci_cpu_init(struct cpufreq_policy *policy)
{
      int result = 0;
      struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
      struct cpufreq_frequency_table *freq_table = pdata->freq_table;

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

      /* Finish platform specific initialization */
      if (pdata->init) {
            result = pdata->init();
            if (result)
                  return result;
      }

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

      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 = policy->min;
            policy->cpuinfo.max_freq = policy->max;
      }

      policy->min = policy->cpuinfo.min_freq;
      policy->max = policy->cpuinfo.max_freq;
      policy->cur = davinci_getspeed(0);

      /*
       * Time measurement across the target() function yields ~1500-1800us
       * time taken with no drivers on notification list.
       * Setting the latency to 2000 us to accomodate addition of drivers
       * to pre/post change notification list.
       */
      policy->cpuinfo.transition_latency = 2000 * 1000;
      return 0;
}

static int davinci_cpu_exit(struct cpufreq_policy *policy)
{
      cpufreq_frequency_table_put_attr(policy->cpu);
      return 0;
}

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

static struct cpufreq_driver davinci_driver = {
      .flags            = CPUFREQ_STICKY,
      .verify           = davinci_verify_speed,
      .target           = davinci_target,
      .get        = davinci_getspeed,
      .init       = davinci_cpu_init,
      .exit       = davinci_cpu_exit,
      .name       = "davinci",
      .attr       = davinci_cpufreq_attr,
};

static int __init davinci_cpufreq_probe(struct platform_device *pdev)
{
      struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
      struct clk *asyncclk;

      if (!pdata)
            return -EINVAL;
      if (!pdata->freq_table)
            return -EINVAL;

      cpufreq.dev = &pdev->dev;

      cpufreq.armclk = clk_get(NULL, "arm");
      if (IS_ERR(cpufreq.armclk)) {
            dev_err(cpufreq.dev, "Unable to get ARM clock\n");
            return PTR_ERR(cpufreq.armclk);
      }

      asyncclk = clk_get(cpufreq.dev, "async");
      if (!IS_ERR(asyncclk)) {
            cpufreq.asyncclk = asyncclk;
            cpufreq.asyncrate = clk_get_rate(asyncclk);
      }

      return cpufreq_register_driver(&davinci_driver);
}

static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
{
      clk_put(cpufreq.armclk);

      if (cpufreq.asyncclk)
            clk_put(cpufreq.asyncclk);

      return cpufreq_unregister_driver(&davinci_driver);
}

static struct platform_driver davinci_cpufreq_driver = {
      .driver = {
            .name  = "cpufreq-davinci",
            .owner       = THIS_MODULE,
      },
      .remove = __exit_p(davinci_cpufreq_remove),
};

static int __init davinci_cpufreq_init(void)
{
      return platform_driver_probe(&davinci_cpufreq_driver,
                                          davinci_cpufreq_probe);
}
late_initcall(davinci_cpufreq_init);


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