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 #define VERY_HI_RATE    900000000
  29
  30 #ifdef CONFIG_ARCH_OMAP1
  31 #define MPU_CLK         "mpu"
  32 #else
  33 #define MPU_CLK         "virt_prcm_set"
  34 #endif
  35
  36 static struct clk *mpu_clk;
  37
  38 /* TODO: Add support for SDRAM timing changes */
  39
  40 int omap_verify_speed(struct cpufreq_policy *policy)
  41 {
  42         if (policy->cpu)
  43                 return -EINVAL;
  44
  45         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  46                                      policy->cpuinfo.max_freq);
  47
  48         policy->min = clk_round_rate(mpu_clk, policy->min * 1000) / 1000;
  49         policy->max = clk_round_rate(mpu_clk, policy->max * 1000) / 1000;
  50         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  51                                      policy->cpuinfo.max_freq);
  52         return 0;
  53 }
  54
  55 unsigned int omap_getspeed(unsigned int cpu)
  56 {
  57         unsigned long rate;
  58
  59         if (cpu)
  60                 return 0;
  61
  62         rate = clk_get_rate(mpu_clk) / 1000;
  63         return rate;
  64 }
  65
  66 static int omap_target(struct cpufreq_policy *policy,
  67                        unsigned int target_freq,
  68                        unsigned int relation)
  69 {
  70         struct cpufreq_freqs freqs;
  71         int ret = 0;
  72
  73         freqs.old = omap_getspeed(0);
  74         freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
  75         freqs.cpu = 0;
  76
  77         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  78         ret = clk_set_rate(mpu_clk, target_freq * 1000);
  79         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  80
  81         return ret;
  82 }
  83
  84 static int __init omap_cpu_init(struct cpufreq_policy *policy)
  85 {
  86         mpu_clk = clk_get(NULL, MPU_CLK);
  87         if (IS_ERR(mpu_clk))
  88                 return PTR_ERR(mpu_clk);
  89
  90         if (policy->cpu != 0)
  91                 return -EINVAL;
  92         policy->cur = policy->min = policy->max = omap_getspeed(0);
  93         policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
  94         policy->cpuinfo.max_freq = clk_round_rate(mpu_clk, VERY_HI_RATE) / 1000;
  95         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
  96
  97         return 0;
  98 }
  99
 100 static int omap_cpu_exit(struct cpufreq_policy *policy)
 101 {
 102         clk_put(mpu_clk);
 103         return 0;
 104 }
 105
 106 static struct cpufreq_driver omap_driver = {
 107         .flags          = CPUFREQ_STICKY,
 108         .verify         = omap_verify_speed,
 109         .target         = omap_target,
 110         .get            = omap_getspeed,
 111         .init           = omap_cpu_init,
 112         .exit           = omap_cpu_exit,
 113         .name           = "omap",
 114 };
 115
 116 static int __init omap_cpufreq_init(void)
 117 {
 118         return cpufreq_register_driver(&omap_driver);
 119 }
 120
 121 arch_initcall(omap_cpufreq_init);