arch/avr32/mach-at32ap/cpufreq.c

   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 }
  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);