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cpufreq.c

/*
 * CPU frequency scaling for u8500
 * Inspired by linux/arch/arm/mach-davinci/cpufreq.c
 *
 * Copyright (C) STMicroelectronics 2009
 * Copyright (C) ST-Ericsson SA 2010
 *
 * License Terms: GNU General Public License v2
 *
 * Author: Sundar Iyer <sundar.iyer@stericsson.com>
 * Author: Martin Persson <martin.persson@stericsson.com>
 * Author: Jonas Aaberg <jonas.aberg@stericsson.com>
 *
 */

#include <linux/platform_device.h>
#include <linux/kernel.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>

#include <mach/hardware.h>
#include <mach/prcmu.h>
#include <mach/prcmu-defs.h>

#define DRIVER_NAME "cpufreq-u8500"
#define CPUFREQ_NAME "u8500"

static struct device *dev;

static struct cpufreq_frequency_table freq_table[] = {
      [0] = {
            .index = 0,
            .frequency = 200000,
      },
      [1] = {
            .index = 1,
            .frequency = 300000,
      },
      [2] = {
            .index = 2,
            .frequency = 600000,
      },
      [3] = {
            /* Used for CPU_OPP_MAX, if available */
            .index = 3,
            .frequency = CPUFREQ_TABLE_END,
      },
      [4] = {
            .index = 4,
            .frequency = CPUFREQ_TABLE_END,
      },
};

static enum prcmu_cpu_opp index2opp[] = {
      CPU_OPP_EXT_CLK,
      CPU_OPP_50,
      CPU_OPP_100,
      CPU_OPP_MAX
};

static int u8500_cpufreq_verify_speed(struct cpufreq_policy *policy)
{
      return cpufreq_frequency_table_verify(policy, freq_table);
}

static int u8500_cpufreq_target(struct cpufreq_policy *policy,
                        unsigned int target_freq,
                        unsigned int relation)
{
      struct cpufreq_freqs freqs;
      unsigned int index;
      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->cpuinfo.min_freq)
            target_freq = policy->cpuinfo.min_freq;
      if (target_freq > policy->cpuinfo.max_freq)
            target_freq = policy->cpuinfo.max_freq;

      ret = cpufreq_frequency_table_target(policy, freq_table,
                                   target_freq, relation, &index);
      if (ret < 0) {
            dev_err(dev, "Could not look up next frequency\n");
            return ret;
      }

      freqs.old = policy->cur;
      freqs.new = freq_table[index].frequency;
      freqs.cpu = policy->cpu;

      if (freqs.old == freqs.new) {
            dev_dbg(dev, "Current and target frequencies are equal\n");
            return 0;
      }

      dev_dbg(dev, "transition: %u --> %u\n", freqs.old, freqs.new);
      cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

      ret = prcmu_set_cpu_opp(index2opp[index]);
      if (ret < 0) {
            dev_err(dev, "Failed to set OPP level\n");
            return ret;
      }

      cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

      return ret;
}

static unsigned int u8500_cpufreq_getspeed(unsigned int cpu)
{
      int i;

      for (i = 0; prcmu_get_cpu_opp() != index2opp[i]; i++)
            ;
      return freq_table[i].frequency;
}

static int __cpuinit u8500_cpu_init(struct cpufreq_policy *policy)
{
      int res;

      BUILD_BUG_ON(ARRAY_SIZE(index2opp) + 1 != ARRAY_SIZE(freq_table));

      if (cpu_is_u8500v2()) {
            freq_table[1].frequency = 400000;
            freq_table[2].frequency = 800000;
            if (prcmu_has_arm_maxopp())
                  freq_table[3].frequency = 1000000;
      }

      /* get policy fields based on the table */
      res = cpufreq_frequency_table_cpuinfo(policy, freq_table);
      if (!res)
            cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
      else {
            dev_err(dev, "u8500-cpufreq : Failed to read policy table\n");
            return res;
      }

      policy->min = policy->cpuinfo.min_freq;
      policy->max = policy->cpuinfo.max_freq;
      policy->cur = u8500_cpufreq_getspeed(policy->cpu);
      policy->governor = CPUFREQ_DEFAULT_GOVERNOR;

      /*
       * FIXME : Need to take time measurement across the target()
       *       function with no/some/all drivers in the notification
       *       list.
       */
      policy->cpuinfo.transition_latency = 200 * 1000; /* in ns */

      /* policy sharing between dual CPUs */
      cpumask_copy(policy->cpus, &cpu_present_map);

      policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;

      return res;
}

static struct freq_attr *u8500_cpufreq_attr[] = {
      &cpufreq_freq_attr_scaling_available_freqs,
      NULL,
};
static int u8500_cpu_exit(struct cpufreq_policy *policy)
{
      cpufreq_frequency_table_put_attr(policy->cpu);
      return 0;
}

static struct cpufreq_driver u8500_driver = {
      .owner = THIS_MODULE,
      .flags = CPUFREQ_STICKY,
      .verify = u8500_cpufreq_verify_speed,
      .target = u8500_cpufreq_target,
      .get = u8500_cpufreq_getspeed,
      .init = u8500_cpu_init,
      .exit = u8500_cpu_exit,
      .name = CPUFREQ_NAME,
      .attr = u8500_cpufreq_attr,
};

static int __init u8500_cpufreq_probe(struct platform_device *pdev)
{
      dev = &pdev->dev;
      return cpufreq_register_driver(&u8500_driver);
}

static int __exit u8500_cpufreq_remove(struct platform_device *pdev)
{
      return cpufreq_unregister_driver(&u8500_driver);
}

static struct platform_driver u8500_cpufreq_driver = {
      .driver = {
            .name  = DRIVER_NAME,
            .owner       = THIS_MODULE,
      },
      .remove = __exit_p(u8500_cpufreq_remove),
};

static int __init u8500_cpufreq_init(void)
{
      return platform_driver_probe(&u8500_cpufreq_driver,
                             &u8500_cpufreq_probe);
}

device_initcall(u8500_cpufreq_init);

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