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cpufreq.c

/*
 * Copyright 2009 Freescale Semiconductor, Inc. All Rights Reserved.
 */

/*
 * The code contained herein is licensed under the GNU General Public
 * License. You may obtain a copy of the GNU General Public License
 * Version 2 or later at the following locations:
 *
 * http://www.opensource.org/licenses/gpl-license.html
 * http://www.gnu.org/copyleft/gpl.html
 */

/*!
 * @file cpufreq.c
 *
 * @brief A driver for the Freescale Semiconductor i.MXC CPUfreq module.
 *
 * The CPUFREQ driver is for controling CPU frequency. It allows you to change
 * the CPU clock speed on the fly.
 *
 * @ingroup PM
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/cpufreq.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/regulator/consumer.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <mach/hardware.h>
#include <asm/setup.h>
#include <mach/clock.h>
#include <asm/cacheflush.h>
#include <linux/hrtimer.h>

int cpu_freq_khz_min;
int cpu_freq_khz_max;
int arm_lpm_clk;
int arm_normal_clk;
int cpufreq_suspended;
int cpufreq_trig_needed;

static struct clk *cpu_clk;
static struct regulator *gp_regulator;
static struct cpu_wp *cpu_wp_tbl;
static struct cpufreq_frequency_table imx_freq_table[4];
extern int low_bus_freq_mode;
extern int high_bus_freq_mode;
extern int dvfs_core_is_active;
extern int cpu_wp_nr;
extern char *gp_reg_id;

extern int set_low_bus_freq(void);
extern int set_high_bus_freq(int high_bus_speed);
extern int low_freq_bus_used(void);

#ifdef CONFIG_ARCH_MX51
extern struct cpu_wp *(*get_cpu_wp)(int *wp);
#endif

int set_cpu_freq(int freq)
{
      int ret = 0;
      int org_cpu_rate;
      int gp_volt = 0;
      int i;

      org_cpu_rate = clk_get_rate(cpu_clk);
      if (org_cpu_rate == freq)
            return ret;

      for (i = 0; i < cpu_wp_nr; i++) {
            if (freq == cpu_wp_tbl[i].cpu_rate)
                  gp_volt = cpu_wp_tbl[i].cpu_voltage;
      }

      if (gp_volt == 0)
            return ret;

      /*Set the voltage for the GP domain. */
      if (freq > org_cpu_rate) {
            ret = regulator_set_voltage(gp_regulator, gp_volt, gp_volt);
            if (ret < 0) {
                  printk(KERN_DEBUG "COULD NOT SET GP VOLTAGE!!!!\n");
                  return ret;
            }
      }
      
      ret = clk_set_rate(cpu_clk, freq);
      if (ret != 0) {
            printk(KERN_DEBUG "cannot set CPU clock rate\n");
            return ret;
      }
      
      if (freq < org_cpu_rate) {
            ret = regulator_set_voltage(gp_regulator, gp_volt, gp_volt);
            if (ret < 0) {
                  printk(KERN_DEBUG "COULD NOT SET GP VOLTAGE!!!!\n");
                  return ret;
            }
      }
      
      return ret;
}

static int mxc_verify_speed(struct cpufreq_policy *policy)
{
      if (policy->cpu != 0)
            return -EINVAL;

      return cpufreq_frequency_table_verify(policy, imx_freq_table);
}

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

      return clk_get_rate(cpu_clk) / 1000;
}

static int calc_frequency_khz(int target, unsigned int relation)
{
      int i;

      if ((target * 1000) == clk_get_rate(cpu_clk))
            return target;

      if (relation == CPUFREQ_RELATION_H) {
            for (i = cpu_wp_nr - 1; i >= 0; i--) {
                  if (imx_freq_table[i].frequency <= target)
                        return imx_freq_table[i].frequency;
            }
      } else if (relation == CPUFREQ_RELATION_L) {
            for (i = 0; i < cpu_wp_nr; i++) {
                  if (imx_freq_table[i].frequency >= target)
                        return imx_freq_table[i].frequency;
            }
      }
      printk(KERN_ERR "Error: No valid cpufreq relation\n");
      return cpu_freq_khz_max;
}

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

      if (dvfs_core_is_active || cpufreq_suspended) {
            target_freq = clk_get_rate(cpu_clk) / 1000;
            freq_Hz = calc_frequency_khz(target_freq, relation) * 1000;
            if (freq_Hz == arm_lpm_clk)
                  freqs.old = cpu_wp_tbl[cpu_wp_nr - 2].cpu_rate / 1000;
            else
                  freqs.old = arm_lpm_clk / 1000;

            freqs.new = freq_Hz / 1000;
            freqs.cpu = 0;
            freqs.flags = 0;
            cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
            cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
            return ret;
      }
      /*
       * Some governors do not respects CPU and policy lower limits
       * which leads to bad things (division by zero etc), ensure
       * that such things do not happen.
       */
      if (target_freq < policy->cpuinfo.min_freq)
            target_freq = policy->cpuinfo.min_freq;

      if (target_freq < policy->min)
            target_freq = policy->min;

      freq_Hz = calc_frequency_khz(target_freq, relation) * 1000;

      freqs.old = clk_get_rate(cpu_clk) / 1000;
      freqs.new = freq_Hz / 1000;
      freqs.cpu = 0;
      freqs.flags = 0;
      low_freq_bus_ready = low_freq_bus_used();
      cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
      if (!dvfs_core_is_active) {
            if ((freq_Hz == arm_lpm_clk) && (!low_bus_freq_mode)
                && (low_freq_bus_ready)) {
                  if (freqs.old != freqs.new)
                        ret = set_cpu_freq(freq_Hz);
                  set_low_bus_freq();

            } else {
                  set_high_bus_freq(0);
                  ret = set_cpu_freq(freq_Hz);
            }
      }

      cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

      return ret;
}

static int __init mxc_cpufreq_driver_init(struct cpufreq_policy *policy)
{
      int ret;
      int i;

      printk(KERN_INFO "i.MXC CPU frequency driver\n");

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

      cpu_clk = clk_get(NULL, "cpu_clk");
      if (IS_ERR(cpu_clk)) {
            printk(KERN_ERR "%s: failed to get cpu clock\n", __func__);
            return PTR_ERR(cpu_clk);
      }

      gp_regulator = regulator_get(NULL, gp_reg_id);
      if (IS_ERR(gp_regulator)) {
            clk_put(cpu_clk);
            printk(KERN_ERR "%s: failed to get gp regulator\n", __func__);
            return PTR_ERR(gp_regulator);
      }

      /* Set the current working point. */
      cpu_wp_tbl = get_cpu_wp(&cpu_wp_nr);

      cpu_freq_khz_min = cpu_wp_tbl[0].cpu_rate / 1000;
      cpu_freq_khz_max = cpu_wp_tbl[0].cpu_rate / 1000;

      for (i = 0; i < cpu_wp_nr; i++) {
            imx_freq_table[cpu_wp_nr - 1 - i].index = cpu_wp_nr - i;
            imx_freq_table[cpu_wp_nr - 1 - i].frequency =
                cpu_wp_tbl[i].cpu_rate / 1000;

            if ((cpu_wp_tbl[i].cpu_rate / 1000) < cpu_freq_khz_min)
                  cpu_freq_khz_min = cpu_wp_tbl[i].cpu_rate / 1000;

            if ((cpu_wp_tbl[i].cpu_rate / 1000) > cpu_freq_khz_max)
                  cpu_freq_khz_max = cpu_wp_tbl[i].cpu_rate / 1000;
      }

      imx_freq_table[i].index = 0;
      imx_freq_table[i].frequency = CPUFREQ_TABLE_END;

      policy->cur = clk_get_rate(cpu_clk) / 1000;
      policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
      policy->min = policy->cpuinfo.min_freq = cpu_freq_khz_min;
      policy->max = policy->cpuinfo.max_freq = cpu_freq_khz_max;

      arm_lpm_clk = cpu_freq_khz_min * 1000;
      arm_normal_clk = cpu_freq_khz_max * 1000;

      /* Manual states, that PLL stabilizes in two CLK32 periods */
      policy->cpuinfo.transition_latency = 10;

      ret = cpufreq_frequency_table_cpuinfo(policy, imx_freq_table);

      if (ret < 0) {
            clk_put(cpu_clk);
            regulator_put(gp_regulator);
            printk(KERN_ERR "%s: failed to register i.MXC CPUfreq\n",
                   __func__);
            return ret;
      }

      cpufreq_frequency_table_get_attr(imx_freq_table, policy->cpu);
      return 0;
}

static int mxc_cpufreq_suspend(struct cpufreq_policy *policy,
                             pm_message_t state)
{
      return 0;
}

static int mxc_cpufreq_resume(struct cpufreq_policy *policy)
{
      return 0;
}

static int mxc_cpufreq_driver_exit(struct cpufreq_policy *policy)
{
      cpufreq_frequency_table_put_attr(policy->cpu);

      /* Reset CPU to 665MHz */
      if (!dvfs_core_is_active)
            set_cpu_freq(arm_normal_clk);
      if (!high_bus_freq_mode)
            set_high_bus_freq(1);

      clk_put(cpu_clk);
      regulator_put(gp_regulator);
      return 0;
}

static struct cpufreq_driver mxc_driver = {
      .flags = CPUFREQ_STICKY,
      .verify = mxc_verify_speed,
      .target = mxc_set_target,
      .get = mxc_get_speed,
      .init = mxc_cpufreq_driver_init,
      .exit = mxc_cpufreq_driver_exit,
      .suspend = mxc_cpufreq_suspend,
      .resume = mxc_cpufreq_resume,
      .name = "imx",
};

static int __devinit mxc_cpufreq_init(void)
{
      return cpufreq_register_driver(&mxc_driver);
}

static void mxc_cpufreq_exit(void)
{
      cpufreq_unregister_driver(&mxc_driver);
}

module_init(mxc_cpufreq_init);
module_exit(mxc_cpufreq_exit);

MODULE_AUTHOR("Freescale Semiconductor, Inc.");
MODULE_DESCRIPTION("CPUfreq driver for i.MX");
MODULE_LICENSE("GPL");

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