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         unsigned int cur = ucv2_getspeed(0);
  50         struct cpufreq_freqs freqs;
  51         struct clk *mclk = clk_get(NULL, "MAIN_CLK");
  52
  53         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  54
  55         if (!clk_set_rate(mclk, target_freq * 1000)) {
  56                 freqs.old = cur;
  57                 freqs.new = target_freq;
  58         }
  59
  60         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
  61
  62         return 0;
  63 }
  64
  65 static int __init ucv2_cpu_init(struct cpufreq_policy *policy)
  66 {
  67         if (policy->cpu != 0)
  68                 return -EINVAL;
  69         policy->min = policy->cpuinfo.min_freq = 250000;
  70         policy->max = policy->cpuinfo.max_freq = 1000000;
  71         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
  72         return 0;
  73 }
  74
  75 static struct cpufreq_driver ucv2_driver = {
  76         .flags          = CPUFREQ_STICKY,
  77         .verify         = ucv2_verify_speed,
  78         .target         = ucv2_target,
  79         .get            = ucv2_getspeed,
  80         .init           = ucv2_cpu_init,
  81         .name           = "UniCore-II",
  82 };
  83
  84 static int __init ucv2_cpufreq_init(void)
  85 {
  86         return cpufreq_register_driver(&ucv2_driver);
  87 }
  88
  89 arch_initcall(ucv2_cpufreq_init);