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cpu-tegra.c

/*
 * arch/arm/mach-tegra/cpu-tegra.c
 *
 * Copyright (C) 2010 Google, Inc.
 *
 * Author:
 *    Colin Cross <ccross@google.com>
 *    Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.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 <asm/system.h>

#include <mach/hardware.h>
#include <mach/clk.h>

/* Frequency table index must be sequential starting at 0 */
static struct cpufreq_frequency_table freq_table[] = {
      { 0, 312000 },
      { 1, 456000 },
      { 2, 608000 },
      { 3, 760000 },
      { 4, 816000 },
      { 5, 912000 },
      { 6, 1000000 },
      { 7, CPUFREQ_TABLE_END },
};

#define NUM_CPUS  2

static struct clk *cpu_clk;

static unsigned long target_cpu_speed[NUM_CPUS];

int tegra_verify_speed(struct cpufreq_policy *policy)
{
      return cpufreq_frequency_table_verify(policy, freq_table);
}

unsigned int tegra_getspeed(unsigned int cpu)
{
      unsigned long rate;

      if (cpu >= NUM_CPUS)
            return 0;

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

static int tegra_update_cpu_speed(void)
{
      int i;
      unsigned long rate = 0;
      int ret = 0;
      struct cpufreq_freqs freqs;

      for_each_online_cpu(i)
            rate = max(rate, target_cpu_speed[i]);

      freqs.old = tegra_getspeed(0);
      freqs.new = rate;

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

      for_each_online_cpu(freqs.cpu)
            cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

#ifdef CONFIG_CPU_FREQ_DEBUG
      printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n",
             freqs.old, freqs.new);
#endif

      ret = clk_set_rate_cansleep(cpu_clk, freqs.new * 1000);
      if (ret) {
            pr_err("cpu-tegra: Failed to set cpu frequency to %d kHz\n",
                  freqs.new);
            return ret;
      }

      for_each_online_cpu(freqs.cpu)
            cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

      return 0;
}

static int tegra_target(struct cpufreq_policy *policy,
                   unsigned int target_freq,
                   unsigned int relation)
{
      int idx;
      unsigned int freq;

      cpufreq_frequency_table_target(policy, freq_table, target_freq,
            relation, &idx);

      freq = freq_table[idx].frequency;

      target_cpu_speed[policy->cpu] = freq;

      return tegra_update_cpu_speed();
}

static int tegra_cpu_init(struct cpufreq_policy *policy)
{
      if (policy->cpu >= NUM_CPUS)
            return -EINVAL;

      cpu_clk = clk_get_sys(NULL, "cpu");
      if (IS_ERR(cpu_clk))
            return PTR_ERR(cpu_clk);

      cpufreq_frequency_table_cpuinfo(policy, freq_table);
      cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
      policy->cur = tegra_getspeed(policy->cpu);
      target_cpu_speed[policy->cpu] = policy->cur;

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

      policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
      cpumask_copy(policy->related_cpus, cpu_possible_mask);

      return 0;
}

static int tegra_cpu_exit(struct cpufreq_policy *policy)
{
      cpufreq_frequency_table_cpuinfo(policy, freq_table);
      clk_put(cpu_clk);
      return 0;
}

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

static struct cpufreq_driver tegra_cpufreq_driver = {
      .verify           = tegra_verify_speed,
      .target           = tegra_target,
      .get        = tegra_getspeed,
      .init       = tegra_cpu_init,
      .exit       = tegra_cpu_exit,
      .name       = "tegra",
      .attr       = tegra_cpufreq_attr,
};

static int __init tegra_cpufreq_init(void)
{
      return cpufreq_register_driver(&tegra_cpufreq_driver);
}

static void __exit tegra_cpufreq_exit(void)
{
        cpufreq_unregister_driver(&tegra_cpufreq_driver);
}


MODULE_AUTHOR("Colin Cross <ccross@android.com>");
MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2");
MODULE_LICENSE("GPL");
module_init(tegra_cpufreq_init);
module_exit(tegra_cpufreq_exit);

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