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/mach-types.h>
  25 #include <asm/io.h>
  26 #include <asm/system.h>
  27
  28 #include <asm/hardware/clock.h>
  29
  30 /* TODO: Add support for SDRAM timing changes */
  31
  32 int omap_verify_speed(struct cpufreq_policy *policy)
  33 {
  34         struct clk * mpu_clk;
  35
  36         if (policy->cpu)
  37                 return -EINVAL;
  38
  39         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  40                                      policy->cpuinfo.max_freq);
  41         mpu_clk = clk_get(NULL, "mpu");
  42         if (IS_ERR(mpu_clk))
  43                 return PTR_ERR(mpu_clk);
  44         policy->min = clk_round_rate(mpu_clk, policy->min * 1000) / 1000;
  45         policy->max = clk_round_rate(mpu_clk, policy->max * 1000) / 1000;
  46         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  47                                      policy->cpuinfo.max_freq);
  48         clk_put(mpu_clk);
  49
  50         return 0;
  51 }
  52
  53 unsigned int omap_getspeed(unsigned int cpu)
  54 {
  55         struct clk * mpu_clk;
  56         unsigned long rate;
  57
  58         if (cpu)
  59                 return 0;
  60
  61         mpu_clk = clk_get(NULL, "mpu");
  62         if (IS_ERR(mpu_clk))
  63                 return 0;
  64         rate = clk_get_rate(mpu_clk) / 1000;
  65         clk_put(mpu_clk);
  66
  67         return rate;
  68 }
  69
  70 static int omap_target(struct cpufreq_policy *policy,
  71                        unsigned int target_freq,
  72                        unsigned int relation)
  73 {
  74         struct clk * mpu_clk;
  75         struct cpufreq_freqs freqs;
  76         int ret = 0;
  77
  78         mpu_clk = clk_get(NULL, "mpu");
  79         if (IS_ERR(mpu_clk))
  80                 return PTR_ERR(mpu_clk);
  81
  82         freqs.old = omap_getspeed(0);
  83         freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
  84         freqs.cpu = 0;
  85
  86         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  87         ret = clk_set_rate(mpu_clk, target_freq * 1000);
  88         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  89         clk_put(mpu_clk);
  90
  91         return ret;
  92 }
  93
  94 static int __init omap_cpu_init(struct cpufreq_policy *policy)
  95 {
  96         struct clk * mpu_clk;
  97
  98         mpu_clk = clk_get(NULL, "mpu");
  99         if (IS_ERR(mpu_clk))
 100                 return PTR_ERR(mpu_clk);
 101
 102         if (policy->cpu != 0)
 103                 return -EINVAL;
 104         policy->cur = policy->min = policy->max = omap_getspeed(0);
 105         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 106         policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
 107         policy->cpuinfo.max_freq = clk_round_rate(mpu_clk, 216000000) / 1000;
 108         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 109         clk_put(mpu_clk);
 110
 111         return 0;
 112 }
 113
 114 static struct cpufreq_driver omap_driver = {
 115         .flags          = CPUFREQ_STICKY,
 116         .verify         = omap_verify_speed,
 117         .target         = omap_target,
 118         .get            = omap_getspeed,
 119         .init           = omap_cpu_init,
 120         .name           = "omap",
 121 };
 122
 123 static int __init omap_cpufreq_init(void)
 124 {
 125         return cpufreq_register_driver(&omap_driver);
 126 }
 127
 128 arch_initcall(omap_cpufreq_init);