release/src-rt-6.x.4708/linux/linux-2.6.36/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 #include <linux/io.h>
  24
  25 #include <mach/hardware.h>
  26 #include <plat/clock.h>
  27 #include <asm/system.h>
  28
  29 #define VERY_HI_RATE    900000000
  30
  31 static struct cpufreq_frequency_table *freq_table;
  32
  33 #ifdef CONFIG_ARCH_OMAP1
  34 #define MPU_CLK         "mpu"
  35 #else
  36 #define MPU_CLK         "virt_prcm_set"
  37 #endif
  38
  39 static struct clk *mpu_clk;
  40
  41 /* TODO: Add support for SDRAM timing changes */
  42
  43 int omap_verify_speed(struct cpufreq_policy *policy)
  44 {
  45         if (freq_table)
  46                 return cpufreq_frequency_table_verify(policy, freq_table);
  47
  48         if (policy->cpu)
  49                 return -EINVAL;
  50
  51         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  52                                      policy->cpuinfo.max_freq);
  53
  54         policy->min = clk_round_rate(mpu_clk, policy->min * 1000) / 1000;
  55         policy->max = clk_round_rate(mpu_clk, policy->max * 1000) / 1000;
  56         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  57                                      policy->cpuinfo.max_freq);
  58         return 0;
  59 }
  60
  61 unsigned int omap_getspeed(unsigned int cpu)
  62 {
  63         unsigned long rate;
  64
  65         if (cpu)
  66                 return 0;
  67
  68         rate = clk_get_rate(mpu_clk) / 1000;
  69         return rate;
  70 }
  71
  72 static int omap_target(struct cpufreq_policy *policy,
  73                        unsigned int target_freq,
  74                        unsigned int relation)
  75 {
  76         struct cpufreq_freqs freqs;
  77         int ret = 0;
  78
  79         /* Ensure desired rate is within allowed range.  Some govenors
  80          * (ondemand) will just pass target_freq=0 to get the minimum. */
  81         if (target_freq < policy->min)
  82                 target_freq = policy->min;
  83         if (target_freq > policy->max)
  84                 target_freq = policy->max;
  85
  86         freqs.old = omap_getspeed(0);
  87         freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
  88         freqs.cpu = 0;
  89
  90         if (freqs.old == freqs.new)
  91                 return ret;
  92
  93         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  94 #ifdef CONFIG_CPU_FREQ_DEBUG
  95         printk(KERN_DEBUG "cpufreq-omap: transition: %u --> %u\n",
  96                freqs.old, freqs.new);
  97 #endif
  98         ret = clk_set_rate(mpu_clk, freqs.new * 1000);
  99         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 100
 101         return ret;
 102 }
 103
 104 static int __init omap_cpu_init(struct cpufreq_policy *policy)
 105 {
 106         int result = 0;
 107
 108         mpu_clk = clk_get(NULL, MPU_CLK);
 109         if (IS_ERR(mpu_clk))
 110                 return PTR_ERR(mpu_clk);
 111
 112         if (policy->cpu != 0)
 113                 return -EINVAL;
 114
 115         policy->cur = policy->min = policy->max = omap_getspeed(0);
 116
 117         clk_init_cpufreq_table(&freq_table);
 118         if (freq_table) {
 119                 result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 120                 if (!result)
 121                         cpufreq_frequency_table_get_attr(freq_table,
 122                                                         policy->cpu);
 123         } else {
 124                 policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
 125                 policy->cpuinfo.max_freq = clk_round_rate(mpu_clk,
 126                                                         VERY_HI_RATE) / 1000;
 127         }
 128
 129         policy->cpuinfo.transition_latency = 300 * 1000;
 130
 131         return 0;
 132 }
 133
 134 static int omap_cpu_exit(struct cpufreq_policy *policy)
 135 {
 136         clk_exit_cpufreq_table(&freq_table);
 137         clk_put(mpu_clk);
 138         return 0;
 139 }
 140
 141 static struct freq_attr *omap_cpufreq_attr[] = {
 142         &cpufreq_freq_attr_scaling_available_freqs,
 143         NULL,
 144 };
 145
 146 static struct cpufreq_driver omap_driver = {
 147         .flags          = CPUFREQ_STICKY,
 148         .verify         = omap_verify_speed,
 149         .target         = omap_target,
 150         .get            = omap_getspeed,
 151         .init           = omap_cpu_init,
 152         .exit           = omap_cpu_exit,
 153         .name           = "omap",
 154         .attr           = omap_cpufreq_attr,
 155 };
 156
 157 static int __init omap_cpufreq_init(void)
 158 {
 159         return cpufreq_register_driver(&omap_driver);
 160 }
 161
 162 arch_initcall(omap_cpufreq_init);
 163
 164 /*
 165  * if ever we want to remove this, upon cleanup call:
 166  *
 167  * cpufreq_unregister_driver()
 168  * cpufreq_frequency_table_put_attr()
 169  */