1: /*
    2:  * Copyright (C) 2004-2007 Atmel Corporation
    3:  *
    4:  * Based on MIPS implementation arch/mips/kernel/time.c
    5:  *   Copyright 2001 MontaVista Software Inc.
    6:  *
    7:  * This program is free software; you can redistribute it and/or modify
    8:  * it under the terms of the GNU General Public License version 2 as
    9:  * published by the Free Software Foundation.
   10:  */
   11: 
   12: /*#define DEBUG*/
   13: 
   14: #include <linux/kernel.h>
   15: #include <linux/types.h>
   16: #include <linux/init.h>
   17: #include <linux/cpufreq.h>
   18: #include <linux/io.h>
   19: #include <linux/clk.h>
   20: #include <linux/err.h>
   21: #include <asm/system.h>
   22: 
   23: static struct clk *cpuclk;
   24: 
   25: static int at32_verify_speed(struct cpufreq_policy *policy)
   26: {
   27:         if (policy->cpu != 0)
   28:                 return -EINVAL;
   29: 
   30:         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
   31:                         policy->cpuinfo.max_freq);
   32:         return 0;
   33: }


guest: linux/2.6.23/arch/avr32/mach-at32ap/cpufreq.c:25-33 on Thu Jun 19 08:51:24 +0900 2008


test test test test


   34: 
   35: static unsigned int at32_get_speed(unsigned int cpu)
   36: {
   37:         /* No SMP support */
   38:         if (cpu)
   39:                 return 0;
   40:         return (unsigned int)((clk_get_rate(cpuclk) + 500) / 1000);
   41: }
   42: 
   43: static int at32_set_target(struct cpufreq_policy *policy,
   44:                           unsigned int target_freq,
   45:                           unsigned int relation)
   46: {
   47:         struct cpufreq_freqs freqs;
   48:         long freq;
   49: 
   50:         /* Convert target_freq from kHz to Hz */
   51:         freq = clk_round_rate(cpuclk, target_freq * 1000);
   52: 
   53:         /* Check if policy->min <= new_freq <= policy->max */
   54:         if(freq < (policy->min * 1000) || freq > (policy->max * 1000))
   55:                 return -EINVAL;
   56: 
   57:         pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
   58: 
   59:         freqs.old = at32_get_speed(0);
   60:         freqs.new = (freq + 500) / 1000;
   61:         freqs.cpu = 0;
   62:         freqs.flags = 0;
   63: 
   64:         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
   65:         clk_set_rate(cpuclk, freq);
   66:         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
   67: 
   68:         pr_debug("cpufreq: set frequency %lu Hz\n", freq);
   69: 
   70:         return 0;
   71: }
   72: 
   73: static int __init at32_cpufreq_driver_init(struct cpufreq_policy *policy)
   74: {
   75:         if (policy->cpu != 0)
   76:                 return -EINVAL;
   77: 
   78:         cpuclk = clk_get(NULL, "cpu");
   79:         if (IS_ERR(cpuclk)) {
   80:                 pr_debug("cpufreq: could not get CPU clk\n");
   81:                 return PTR_ERR(cpuclk);
   82:         }
   83: 
   84:         policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
   85:         policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
   86:         policy->cpuinfo.transition_latency = 0;
   87:         policy->cur = at32_get_speed(0);
   88:         policy->min = policy->cpuinfo.min_freq;
   89:         policy->max = policy->cpuinfo.max_freq;
   90:         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
   91: 
   92:         printk("cpufreq: AT32AP CPU frequency driver\n");
   93: 
   94:         return 0;
   95: }
   96: 
   97: static struct cpufreq_driver at32_driver = {
   98:         .name          = "at32ap",
   99:         .owner         = THIS_MODULE,
  100:         .init          = at32_cpufreq_driver_init,
  101:         .verify                = at32_verify_speed,
  102:         .target                = at32_set_target,
  103:         .get           = at32_get_speed,
  104:         .flags         = CPUFREQ_STICKY,
  105: };
  106: 
  107: static int __init at32_cpufreq_init(void)
  108: {
  109:         return cpufreq_register_driver(&at32_driver);
  110: }
  111: 
  112: arch_initcall(at32_cpufreq_init);