arch/arm/mach-davinci/cpufreq.c

   1 /*
   2  * CPU frequency scaling for DaVinci
   3  *
   4  * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
   5  *
   6  * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
   7  *
   8  *  Copyright (C) 2005 Nokia Corporation
   9  *  Written by Tony Lindgren <tony@atomide.com>
  10  *
  11  *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
  12  *
  13  * Copyright (C) 2007-2008 Texas Instruments, Inc.
  14  * Updated to support OMAP3
  15  * Rajendra Nayak <rnayak@ti.com>
  16  *
  17  * This program is free software; you can redistribute it and/or modify
  18  * it under the terms of the GNU General Public License version 2 as
  19  * published by the Free Software Foundation.
  20  */
  21 #include <linux/types.h>
  22 #include <linux/cpufreq.h>
  23 #include <linux/init.h>
  24 #include <linux/err.h>
  25 #include <linux/clk.h>
  26 #include <linux/platform_device.h>
  27
  28 #include <mach/hardware.h>
  29 #include <mach/cpufreq.h>
  30 #include <mach/common.h>
  31
  32 #include "clock.h"
  33
  34 struct davinci_cpufreq {
  35         struct device *dev;
  36         struct clk *armclk;
  37 };
  38 static struct davinci_cpufreq cpufreq;
  39
  40 static int davinci_verify_speed(struct cpufreq_policy *policy)
  41 {
  42         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  43         struct cpufreq_frequency_table *freq_table = pdata->freq_table;
  44         struct clk *armclk = cpufreq.armclk;
  45
  46         if (freq_table)
  47                 return cpufreq_frequency_table_verify(policy, freq_table);
  48
  49         if (policy->cpu)
  50                 return -EINVAL;
  51
  52         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  53                                      policy->cpuinfo.max_freq);
  54
  55         policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
  56         policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
  57         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  58                                                 policy->cpuinfo.max_freq);
  59         return 0;
  60 }
  61
  62 static unsigned int davinci_getspeed(unsigned int cpu)
  63 {
  64         if (cpu)
  65                 return 0;
  66
  67         return clk_get_rate(cpufreq.armclk) / 1000;
  68 }
  69
  70 static int davinci_target(struct cpufreq_policy *policy,
  71                                 unsigned int target_freq, unsigned int relation)
  72 {
  73         int ret = 0;
  74         unsigned int idx;
  75         struct cpufreq_freqs freqs;
  76         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  77         struct clk *armclk = cpufreq.armclk;
  78
  79         /*
  80          * Ensure desired rate is within allowed range.  Some govenors
  81          * (ondemand) will just pass target_freq=0 to get the minimum.
  82          */
  83         if (target_freq < policy->cpuinfo.min_freq)
  84                 target_freq = policy->cpuinfo.min_freq;
  85         if (target_freq > policy->cpuinfo.max_freq)
  86                 target_freq = policy->cpuinfo.max_freq;
  87
  88         freqs.old = davinci_getspeed(0);
  89         freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000;
  90         freqs.cpu = 0;
  91
  92         if (freqs.old == freqs.new)
  93                 return ret;
  94
  95         cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER,
  96                         dev_driver_string(cpufreq.dev),
  97                         "transition: %u --> %u\n", freqs.old, freqs.new);
  98
  99         ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
 100                                                 freqs.new, relation, &idx);
 101         if (ret)
 102                 return -EINVAL;
 103
 104         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 105
 106         /* if moving to higher frequency, up the voltage beforehand */
 107         if (pdata->set_voltage && freqs.new > freqs.old) {
 108                 ret = pdata->set_voltage(idx);
 109                 if (ret)
 110                         goto out;
 111         }
 112
 113         ret = clk_set_rate(armclk, idx);
 114         if (ret)
 115                 goto out;
 116
 117         /* if moving to lower freq, lower the voltage after lowering freq */
 118         if (pdata->set_voltage && freqs.new < freqs.old)
 119                 pdata->set_voltage(idx);
 120
 121 out:
 122         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 123
 124         return ret;
 125 }
 126
 127 static int __init davinci_cpu_init(struct cpufreq_policy *policy)
 128 {
 129         int result = 0;
 130         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
 131         struct cpufreq_frequency_table *freq_table = pdata->freq_table;
 132
 133         if (policy->cpu != 0)
 134                 return -EINVAL;
 135
 136         /* Finish platform specific initialization */
 137         if (pdata->init) {
 138                 result = pdata->init();
 139                 if (result)
 140                         return result;
 141         }
 142
 143         policy->cur = policy->min = policy->max = davinci_getspeed(0);
 144
 145         if (freq_table) {
 146                 result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 147                 if (!result)
 148                         cpufreq_frequency_table_get_attr(freq_table,
 149                                                         policy->cpu);
 150         } else {
 151                 policy->cpuinfo.min_freq = policy->min;
 152                 policy->cpuinfo.max_freq = policy->max;
 153         }
 154
 155         policy->min = policy->cpuinfo.min_freq;
 156         policy->max = policy->cpuinfo.max_freq;
 157         policy->cur = davinci_getspeed(0);
 158
 159         /*
 160          * Time measurement across the target() function yields ~1500-1800us
 161          * time taken with no drivers on notification list.
 162          * Setting the latency to 2000 us to accomodate addition of drivers
 163          * to pre/post change notification list.
 164          */
 165         policy->cpuinfo.transition_latency = 2000 * 1000;
 166         return 0;
 167 }
 168
 169 static int davinci_cpu_exit(struct cpufreq_policy *policy)
 170 {
 171         cpufreq_frequency_table_put_attr(policy->cpu);
 172         return 0;
 173 }
 174
 175 static struct freq_attr *davinci_cpufreq_attr[] = {
 176         &cpufreq_freq_attr_scaling_available_freqs,
 177         NULL,
 178 };
 179
 180 static struct cpufreq_driver davinci_driver = {
 181         .flags          = CPUFREQ_STICKY,
 182         .verify         = davinci_verify_speed,
 183         .target         = davinci_target,
 184         .get            = davinci_getspeed,
 185         .init           = davinci_cpu_init,
 186         .exit           = davinci_cpu_exit,
 187         .name           = "davinci",
 188         .attr           = davinci_cpufreq_attr,
 189 };
 190
 191 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
 192 {
 193         struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
 194
 195         if (!pdata)
 196                 return -EINVAL;
 197         if (!pdata->freq_table)
 198                 return -EINVAL;
 199
 200         cpufreq.dev = &pdev->dev;
 201
 202         cpufreq.armclk = clk_get(NULL, "arm");
 203         if (IS_ERR(cpufreq.armclk)) {
 204                 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
 205                 return PTR_ERR(cpufreq.armclk);
 206         }
 207
 208         return cpufreq_register_driver(&davinci_driver);
 209 }
 210
 211 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
 212 {
 213         clk_put(cpufreq.armclk);
 214
 215         return cpufreq_unregister_driver(&davinci_driver);
 216 }
 217
 218 static struct platform_driver davinci_cpufreq_driver = {
 219         .driver = {
 220                 .name    = "cpufreq-davinci",
 221                 .owner   = THIS_MODULE,
 222         },
 223         .remove = __exit_p(davinci_cpufreq_remove),
 224 };
 225
 226 static int __init davinci_cpufreq_init(void)
 227 {
 228         return platform_driver_probe(&davinci_cpufreq_driver,
 229                                                         davinci_cpufreq_probe);
 230 }
 231 late_initcall(davinci_cpufreq_init);
 232