LXR linux/drivers/cpufreq/unicore2-cpufreq.c

   1/*
   2 * clock scaling for the UniCore-II
   3 *
   4 * Code specific to PKUnity SoC and UniCore ISA
   5 *
   6 *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
   7 *      Copyright (C) 2001-2010 Guan Xuetao
   8 *
   9 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License version 2 as
  11 * published by the Free Software Foundation.
  12 */
  13
  14#include <linux/err.h>
  15#include <linux/kernel.h>
  16#include <linux/types.h>
  17#include <linux/init.h>
  18#include <linux/clk.h>
  19#include <linux/cpufreq.h>
  20
  21#include <mach/hardware.h>
  22
  23static struct cpufreq_driver ucv2_driver;
  24
  25/* make sure that only the "userspace" governor is run
  26 * -- anything else wouldn't make sense on this platform, anyway.
  27 */
  28static int ucv2_verify_speed(struct cpufreq_policy *policy)
  29{
  30        if (policy->cpu)
  31                return -EINVAL;
  32
  33        cpufreq_verify_within_cpu_limits(policy);
  34        return 0;
  35}
  36
  37static int ucv2_target(struct cpufreq_policy *policy,
  38                         unsigned int target_freq,
  39                         unsigned int relation)
  40{
  41        struct cpufreq_freqs freqs;
  42        int ret;
  43
  44        freqs.old = policy->cur;
  45        freqs.new = target_freq;
  46
  47        cpufreq_freq_transition_begin(policy, &freqs);
  48        ret = clk_set_rate(policy->clk, target_freq * 1000);
  49        cpufreq_freq_transition_end(policy, &freqs, ret);
  50
  51        return ret;
  52}
  53
  54static int __init ucv2_cpu_init(struct cpufreq_policy *policy)
  55{
  56        if (policy->cpu != 0)
  57                return -EINVAL;
  58
  59        policy->min = policy->cpuinfo.min_freq = 250000;
  60        policy->max = policy->cpuinfo.max_freq = 1000000;
  61        policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
  62        policy->clk = clk_get(NULL, "MAIN_CLK");
  63        return PTR_ERR_OR_ZERO(policy->clk);
  64}
  65
  66static struct cpufreq_driver ucv2_driver = {
  67        .flags          = CPUFREQ_STICKY,
  68        .verify         = ucv2_verify_speed,
  69        .target         = ucv2_target,
  70        .get            = cpufreq_generic_get,
  71        .init           = ucv2_cpu_init,
  72        .name           = "UniCore-II",
  73};
  74
  75static int __init ucv2_cpufreq_init(void)
  76{
  77        return cpufreq_register_driver(&ucv2_driver);
  78}
  79
  80arch_initcall(ucv2_cpufreq_init);
  81