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 #include <linux/clk.h>
  23
  24 #include <asm/hardware.h>
  25 #include <asm/io.h>
  26 #include <asm/system.h>
  27
  28 /* TODO: Add support for SDRAM timing changes */
  29
  30 int omap_verify_speed(struct cpufreq_policy *policy)
  31 {
  32         struct clk * mpu_clk;
  33
  34         if (policy->cpu)
  35                 return -EINVAL;
  36
  37         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  38                                      policy->cpuinfo.max_freq);
  39         mpu_clk = clk_get(NULL, "mpu");
  40         if (IS_ERR(mpu_clk))
  41                 return PTR_ERR(mpu_clk);
  42         policy->min = clk_round_rate(mpu_clk, policy->min * 1000) / 1000;
  43         policy->max = clk_round_rate(mpu_clk, policy->max * 1000) / 1000;
  44         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  45                                      policy->cpuinfo.max_freq);
  46         clk_put(mpu_clk);
  47
  48         return 0;
  49 }
  50
  51 unsigned int omap_getspeed(unsigned int cpu)
  52 {
  53         struct clk * mpu_clk;
  54         unsigned long rate;
  55
  56         if (cpu)
  57                 return 0;
  58
  59         mpu_clk = clk_get(NULL, "mpu");
  60         if (IS_ERR(mpu_clk))
  61                 return 0;
  62         rate = clk_get_rate(mpu_clk) / 1000;
  63         clk_put(mpu_clk);
  64
  65         return rate;
  66 }
  67
  68 static int omap_target(struct cpufreq_policy *policy,
  69                        unsigned int target_freq,
  70                        unsigned int relation)
  71 {
  72         struct clk * mpu_clk;
  73         struct cpufreq_freqs freqs;
  74         int ret = 0;
  75
  76         mpu_clk = clk_get(NULL, "mpu");
  77         if (IS_ERR(mpu_clk))
  78                 return PTR_ERR(mpu_clk);
  79
  80         freqs.old = omap_getspeed(0);
  81         freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
  82         freqs.cpu = 0;
  83
  84         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  85         ret = clk_set_rate(mpu_clk, target_freq * 1000);
  86         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  87         clk_put(mpu_clk);
  88
  89         return ret;
  90 }
  91
  92 static int __init omap_cpu_init(struct cpufreq_policy *policy)
  93 {
  94         struct clk * mpu_clk;
  95
  96         mpu_clk = clk_get(NULL, "mpu");
  97         if (IS_ERR(mpu_clk))
  98                 return PTR_ERR(mpu_clk);
  99
 100         if (policy->cpu != 0)
 101                 return -EINVAL;
 102         policy->cur = policy->min = policy->max = omap_getspeed(0);
 103         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 104         policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
 105         policy->cpuinfo.max_freq = clk_round_rate(mpu_clk, 216000000) / 1000;
 106         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 107         clk_put(mpu_clk);
 108
 109         return 0;
 110 }
 111
 112 static struct cpufreq_driver omap_driver = {
 113         .flags          = CPUFREQ_STICKY,
 114         .verify         = omap_verify_speed,
 115         .target         = omap_target,
 116         .get            = omap_getspeed,
 117         .init           = omap_cpu_init,
 118         .name           = "omap",
 119 };
 120
 121 static int __init omap_cpufreq_init(void)
 122 {
 123         return cpufreq_register_driver(&omap_driver);
 124 }
 125
 126 arch_initcall(omap_cpufreq_init);