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                 pdata->set_voltage(idx);
 109
 110         ret = clk_set_rate(armclk, idx);
 111
 112         /* if moving to lower freq, lower the voltage after lowering freq */
 113         if (pdata->set_voltage && freqs.new < freqs.old)
 114                 pdata->set_voltage(idx);
 115
 116         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 117
 118         return ret;
 119 }
 120
 121 static int __init davinci_cpu_init(struct cpufreq_policy *policy)
 122 {
 123         int result = 0;
 124         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
 125         struct cpufreq_frequency_table *freq_table = pdata->freq_table;
 126
 127         if (policy->cpu != 0)
 128                 return -EINVAL;
 129
 130         /* Finish platform specific initialization */
 131         if (pdata->init) {
 132                 result = pdata->init();
 133                 if (result)
 134                         return result;
 135         }
 136
 137         policy->cur = policy->min = policy->max = davinci_getspeed(0);
 138
 139         if (freq_table) {
 140                 result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 141                 if (!result)
 142                         cpufreq_frequency_table_get_attr(freq_table,
 143                                                         policy->cpu);
 144         } else {
 145                 policy->cpuinfo.min_freq = policy->min;
 146                 policy->cpuinfo.max_freq = policy->max;
 147         }
 148
 149         policy->min = policy->cpuinfo.min_freq;
 150         policy->max = policy->cpuinfo.max_freq;
 151         policy->cur = davinci_getspeed(0);
 152
 153         /*
 154          * Time measurement across the target() function yields ~1500-1800us
 155          * time taken with no drivers on notification list.
 156          * Setting the latency to 2000 us to accomodate addition of drivers
 157          * to pre/post change notification list.
 158          */
 159         policy->cpuinfo.transition_latency = 2000 * 1000;
 160         return 0;
 161 }
 162
 163 static int davinci_cpu_exit(struct cpufreq_policy *policy)
 164 {
 165         cpufreq_frequency_table_put_attr(policy->cpu);
 166         return 0;
 167 }
 168
 169 static struct freq_attr *davinci_cpufreq_attr[] = {
 170         &cpufreq_freq_attr_scaling_available_freqs,
 171         NULL,
 172 };
 173
 174 static struct cpufreq_driver davinci_driver = {
 175         .flags          = CPUFREQ_STICKY,
 176         .verify         = davinci_verify_speed,
 177         .target         = davinci_target,
 178         .get            = davinci_getspeed,
 179         .init           = davinci_cpu_init,
 180         .exit           = davinci_cpu_exit,
 181         .name           = "davinci",
 182         .attr           = davinci_cpufreq_attr,
 183 };
 184
 185 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
 186 {
 187         struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
 188
 189         if (!pdata)
 190                 return -EINVAL;
 191         if (!pdata->freq_table)
 192                 return -EINVAL;
 193
 194         cpufreq.dev = &pdev->dev;
 195
 196         cpufreq.armclk = clk_get(NULL, "arm");
 197         if (IS_ERR(cpufreq.armclk)) {
 198                 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
 199                 return PTR_ERR(cpufreq.armclk);
 200         }
 201
 202         return cpufreq_register_driver(&davinci_driver);
 203 }
 204
 205 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
 206 {
 207         clk_put(cpufreq.armclk);
 208
 209         return cpufreq_unregister_driver(&davinci_driver);
 210 }
 211
 212 static struct platform_driver davinci_cpufreq_driver = {
 213         .driver = {
 214                 .name    = "cpufreq-davinci",
 215                 .owner   = THIS_MODULE,
 216         },
 217         .remove = __exit_p(davinci_cpufreq_remove),
 218 };
 219
 220 static int __init davinci_cpufreq_init(void)
 221 {
 222         return platform_driver_probe(&davinci_cpufreq_driver,
 223                                                         davinci_cpufreq_probe);
 224 }
 225 late_initcall(davinci_cpufreq_init);
 226