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/kernel.h>
  15 #include <linux/types.h>
  16 #include <linux/init.h>
  17 #include <linux/clk.h>
  18 #include <linux/cpufreq.h>
  19
  20 #include <mach/hardware.h>
  21
  22 static struct cpufreq_driver ucv2_driver;
  23
  24 /* make sure that only the "userspace" governor is run
  25  * -- anything else wouldn't make sense on this platform, anyway.
  26  */
  27 static int ucv2_verify_speed(struct cpufreq_policy *policy)
  28 {
  29         if (policy->cpu)
  30                 return -EINVAL;
  31
  32         cpufreq_verify_within_cpu_limits(policy);
  33         return 0;
  34 }
  35
  36 static unsigned int ucv2_getspeed(unsigned int cpu)
  37 {
  38         struct clk *mclk = clk_get(NULL, "MAIN_CLK");
  39
  40         if (cpu)
  41                 return 0;
  42         return clk_get_rate(mclk)/1000;
  43 }
  44
  45 static int ucv2_target(struct cpufreq_policy *policy,
  46                          unsigned int target_freq,
  47                          unsigned int relation)
  48 {
  49         struct cpufreq_freqs freqs;
  50         struct clk *mclk = clk_get(NULL, "MAIN_CLK");
  51         int ret;
  52
  53         freqs.old = policy->cur;
  54         freqs.new = target_freq;
  55
  56         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  57         ret = clk_set_rate(mclk, target_freq * 1000);
  58         cpufreq_notify_post_transition(policy, &freqs, ret);
  59
  60         return ret;
  61 }
  62
  63 static int __init ucv2_cpu_init(struct cpufreq_policy *policy)
  64 {
  65         if (policy->cpu != 0)
  66                 return -EINVAL;
  67         policy->min = policy->cpuinfo.min_freq = 250000;
  68         policy->max = policy->cpuinfo.max_freq = 1000000;
  69         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
  70         return 0;
  71 }
  72
  73 static struct cpufreq_driver ucv2_driver = {
  74         .flags          = CPUFREQ_STICKY,
  75         .verify         = ucv2_verify_speed,
  76         .target         = ucv2_target,
  77         .get            = ucv2_getspeed,
  78         .init           = ucv2_cpu_init,
  79         .name           = "UniCore-II",
  80 };
  81
  82 static int __init ucv2_cpufreq_init(void)
  83 {
  84         return cpufreq_register_driver(&ucv2_driver);
  85 }
  86
  87 arch_initcall(ucv2_cpufreq_init);