Logo Search packages:      
Sourcecode: linux version File versions  Download package

cpufreq.c

/*
 * Copyright (C) 2010 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
 */

/*
 * 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.
 */

#include <linux/cpufreq.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <mach/hardware.h>
#include <mach/clock.h>

#define CLK32_FREQ      32768
#define NANOSECOND      (1000 * 1000 * 1000)

struct cpu_op *(*get_cpu_op)(int *op);

static int cpu_freq_khz_min;
static int cpu_freq_khz_max;

static struct clk *cpu_clk;
static struct cpufreq_frequency_table *imx_freq_table;

static int cpu_op_nr;
static struct cpu_op *cpu_op_tbl;

static int set_cpu_freq(int freq)
{
      int ret = 0;
      int org_cpu_rate;

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

      ret = clk_set_rate(cpu_clk, freq);
      if (ret != 0) {
            printk(KERN_DEBUG "cannot set CPU clock rate\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 mxc_set_target(struct cpufreq_policy *policy,
                    unsigned int target_freq, unsigned int relation)
{
      struct cpufreq_freqs freqs;
      int freq_Hz;
      int ret = 0;
      unsigned int index;

      cpufreq_frequency_table_target(policy, imx_freq_table,
                  target_freq, relation, &index);
      freq_Hz = imx_freq_table[index].frequency * 1000;

      freqs.old = clk_get_rate(cpu_clk) / 1000;
      freqs.new = freq_Hz / 1000;
      freqs.cpu = 0;
      freqs.flags = 0;
      cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

      ret = set_cpu_freq(freq_Hz);

      cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

      return ret;
}

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

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

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

      if (!get_cpu_op)
            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);
      }

      cpu_op_tbl = get_cpu_op(&cpu_op_nr);

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

      imx_freq_table = kmalloc(
            sizeof(struct cpufreq_frequency_table) * (cpu_op_nr + 1),
                  GFP_KERNEL);
      if (!imx_freq_table) {
            ret = -ENOMEM;
            goto err1;
      }

      for (i = 0; i < cpu_op_nr; i++) {
            imx_freq_table[i].index = i;
            imx_freq_table[i].frequency = cpu_op_tbl[i].cpu_rate / 1000;

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

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

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

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

      /* Manual states, that PLL stabilizes in two CLK32 periods */
      policy->cpuinfo.transition_latency = 2 * NANOSECOND / CLK32_FREQ;

      ret = cpufreq_frequency_table_cpuinfo(policy, imx_freq_table);

      if (ret < 0) {
            printk(KERN_ERR "%s: failed to register i.MXC CPUfreq \
                        with error code %d\n", __func__, ret);
            goto err;
      }

      cpufreq_frequency_table_get_attr(imx_freq_table, policy->cpu);
      return 0;
err:
      kfree(imx_freq_table);
err1:
      clk_put(cpu_clk);
      return ret;
}

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

      set_cpu_freq(cpu_freq_khz_max * 1000);
      clk_put(cpu_clk);
      kfree(imx_freq_table);
      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_init,
      .exit = mxc_cpufreq_exit,
      .name = "imx",
};

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

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

module_init(mxc_cpufreq_driver_init);
module_exit(mxc_cpufreq_driver_exit);

MODULE_AUTHOR("Freescale Semiconductor Inc. Yong Shen <yong.shen@linaro.org>");
MODULE_DESCRIPTION("CPUfreq driver for i.MX");
MODULE_LICENSE("GPL");

Generated by  Doxygen 1.6.0   Back to index