drivers/cpufreq/unicore2-cpufreq.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * clock scaling for the UniCore-II
   4  *
   5  * Code specific to PKUnity SoC and UniCore ISA
   6  *
   7  *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
   8  *      Copyright (C) 2001-2010 Guan Xuetao
   9  */
  10
  11 #include <linux/err.h>
  12 #include <linux/kernel.h>
  13 #include <linux/types.h>
  14 #include <linux/init.h>
  15 #include <linux/clk.h>
  16 #include <linux/cpufreq.h>
  17
  18 #include <mach/hardware.h>
  19
  20 static struct cpufreq_driver ucv2_driver;
  21
  22 /* make sure that only the "userspace" governor is run
  23  * -- anything else wouldn't make sense on this platform, anyway.
  24  */
  25 static int ucv2_verify_speed(struct cpufreq_policy *policy)
  26 {
  27         if (policy->cpu)
  28                 return -EINVAL;
  29
  30         cpufreq_verify_within_cpu_limits(policy);
  31         return 0;
  32 }
  33
  34 static int ucv2_target(struct cpufreq_policy *policy,
  35                          unsigned int target_freq,
  36                          unsigned int relation)
  37 {
  38         struct cpufreq_freqs freqs;
  39         int ret;
  40
  41         freqs.old = policy->cur;
  42         freqs.new = target_freq;
  43
  44         cpufreq_freq_transition_begin(policy, &freqs);
  45         ret = clk_set_rate(policy->clk, target_freq * 1000);
  46         cpufreq_freq_transition_end(policy, &freqs, ret);
  47
  48         return ret;
  49 }
  50
  51 static int __init ucv2_cpu_init(struct cpufreq_policy *policy)
  52 {
  53         if (policy->cpu != 0)
  54                 return -EINVAL;
  55
  56         policy->min = policy->cpuinfo.min_freq = 250000;
  57         policy->max = policy->cpuinfo.max_freq = 1000000;
  58         policy->clk = clk_get(NULL, "MAIN_CLK");
  59         return PTR_ERR_OR_ZERO(policy->clk);
  60 }
  61
  62 static struct cpufreq_driver ucv2_driver = {
  63         .flags          = CPUFREQ_STICKY | CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
  64         .verify         = ucv2_verify_speed,
  65         .target         = ucv2_target,
  66         .get            = cpufreq_generic_get,
  67         .init           = ucv2_cpu_init,
  68         .name           = "UniCore-II",
  69 };
  70
  71 static int __init ucv2_cpufreq_init(void)
  72 {
  73         return cpufreq_register_driver(&ucv2_driver);
  74 }
  75
  76 arch_initcall(ucv2_cpufreq_init);