arch/arm/plat-omap/cpu-omap.c

   1 /*
   2  *  linux/arch/arm/plat-omap/cpu-omap.c
   3  *
   4  *  CPU frequency scaling for OMAP
   5  *
   6  *  Copyright (C) 2005 Nokia Corporation
   7  *  Written by Tony Lindgren <tony@atomide.com>
   8  *
   9  *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  */
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/sched.h>
  18 #include <linux/cpufreq.h>
  19 #include <linux/delay.h>
  20 #include <linux/init.h>
  21 #include <linux/err.h>
  22
  23 #include <asm/hardware.h>
  24 #include <asm/io.h>
  25 #include <asm/system.h>
  26
  27 #include <asm/hardware/clock.h>
  28
  29 /* TODO: Add support for SDRAM timing changes */
  30
  31 int omap_verify_speed(struct cpufreq_policy *policy)
  32 {
  33         struct clk * mpu_clk;
  34
  35         if (policy->cpu)
  36                 return -EINVAL;
  37
  38         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  39                                      policy->cpuinfo.max_freq);
  40         mpu_clk = clk_get(NULL, "mpu");
  41         if (IS_ERR(mpu_clk))
  42                 return PTR_ERR(mpu_clk);
  43         policy->min = clk_round_rate(mpu_clk, policy->min * 1000) / 1000;
  44         policy->max = clk_round_rate(mpu_clk, policy->max * 1000) / 1000;
  45         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  46                                      policy->cpuinfo.max_freq);
  47         clk_put(mpu_clk);
  48
  49         return 0;
  50 }
  51
  52 unsigned int omap_getspeed(unsigned int cpu)
  53 {
  54         struct clk * mpu_clk;
  55         unsigned long rate;
  56
  57         if (cpu)
  58                 return 0;
  59
  60         mpu_clk = clk_get(NULL, "mpu");
  61         if (IS_ERR(mpu_clk))
  62                 return 0;
  63         rate = clk_get_rate(mpu_clk) / 1000;
  64         clk_put(mpu_clk);
  65
  66         return rate;
  67 }
  68
  69 static int omap_target(struct cpufreq_policy *policy,
  70                        unsigned int target_freq,
  71                        unsigned int relation)
  72 {
  73         struct clk * mpu_clk;
  74         struct cpufreq_freqs freqs;
  75         int ret = 0;
  76
  77         mpu_clk = clk_get(NULL, "mpu");
  78         if (IS_ERR(mpu_clk))
  79                 return PTR_ERR(mpu_clk);
  80
  81         freqs.old = omap_getspeed(0);
  82         freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
  83         freqs.cpu = 0;
  84
  85         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  86         ret = clk_set_rate(mpu_clk, target_freq * 1000);
  87         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  88         clk_put(mpu_clk);
  89
  90         return ret;
  91 }
  92
  93 static int __init omap_cpu_init(struct cpufreq_policy *policy)
  94 {
  95         struct clk * mpu_clk;
  96
  97         mpu_clk = clk_get(NULL, "mpu");
  98         if (IS_ERR(mpu_clk))
  99                 return PTR_ERR(mpu_clk);
 100
 101         if (policy->cpu != 0)
 102                 return -EINVAL;
 103         policy->cur = policy->min = policy->max = omap_getspeed(0);
 104         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 105         policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
 106         policy->cpuinfo.max_freq = clk_round_rate(mpu_clk, 216000000) / 1000;
 107         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 108         clk_put(mpu_clk);
 109
 110         return 0;
 111 }
 112
 113 static struct cpufreq_driver omap_driver = {
 114         .flags          = CPUFREQ_STICKY,
 115         .verify         = omap_verify_speed,
 116         .target         = omap_target,
 117         .get            = omap_getspeed,
 118         .init           = omap_cpu_init,
 119         .name           = "omap",
 120 };
 121
 122 static int __init omap_cpufreq_init(void)
 123 {
 124         return cpufreq_register_driver(&omap_driver);
 125 }
 126
 127 arch_initcall(omap_cpufreq_init);