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 #include <linux/export.h>
  28
  29 #include <mach/hardware.h>
  30 #include <mach/cpufreq.h>
  31 #include <mach/common.h>
  32
  33 #include "clock.h"
  34
  35 struct davinci_cpufreq {
  36         struct device *dev;
  37         struct clk *armclk;
  38         struct clk *asyncclk;
  39         unsigned long asyncrate;
  40 };
  41 static struct davinci_cpufreq cpufreq;
  42
  43 static int davinci_verify_speed(struct cpufreq_policy *policy)
  44 {
  45         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  46         struct cpufreq_frequency_table *freq_table = pdata->freq_table;
  47         struct clk *armclk = cpufreq.armclk;
  48
  49         if (freq_table)
  50                 return cpufreq_frequency_table_verify(policy, freq_table);
  51
  52         if (policy->cpu)
  53                 return -EINVAL;
  54
  55         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  56                                      policy->cpuinfo.max_freq);
  57
  58         policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
  59         policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
  60         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  61                                                 policy->cpuinfo.max_freq);
  62         return 0;
  63 }
  64
  65 static unsigned int davinci_getspeed(unsigned int cpu)
  66 {
  67         if (cpu)
  68                 return 0;
  69
  70         return clk_get_rate(cpufreq.armclk) / 1000;
  71 }
  72
  73 static int davinci_target(struct cpufreq_policy *policy,
  74                                 unsigned int target_freq, unsigned int relation)
  75 {
  76         int ret = 0;
  77         unsigned int idx;
  78         struct cpufreq_freqs freqs;
  79         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  80         struct clk *armclk = cpufreq.armclk;
  81
  82         /*
  83          * Ensure desired rate is within allowed range.  Some govenors
  84          * (ondemand) will just pass target_freq=0 to get the minimum.
  85          */
  86         if (target_freq < policy->cpuinfo.min_freq)
  87                 target_freq = policy->cpuinfo.min_freq;
  88         if (target_freq > policy->cpuinfo.max_freq)
  89                 target_freq = policy->cpuinfo.max_freq;
  90
  91         freqs.old = davinci_getspeed(0);
  92         freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000;
  93         freqs.cpu = 0;
  94
  95         if (freqs.old == freqs.new)
  96                 return ret;
  97
  98         dev_dbg(&cpufreq.dev, "transition: %u --> %u\n", freqs.old, freqs.new);
  99
 100         ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
 101                                                 freqs.new, relation, &idx);
 102         if (ret)
 103                 return -EINVAL;
 104
 105         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 106
 107         /* if moving to higher frequency, up the voltage beforehand */
 108         if (pdata->set_voltage && freqs.new > freqs.old) {
 109                 ret = pdata->set_voltage(idx);
 110                 if (ret)
 111                         goto out;
 112         }
 113
 114         ret = clk_set_rate(armclk, idx);
 115         if (ret)
 116                 goto out;
 117
 118         if (cpufreq.asyncclk) {
 119                 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
 120                 if (ret)
 121                         goto out;
 122         }
 123
 124         /* if moving to lower freq, lower the voltage after lowering freq */
 125         if (pdata->set_voltage && freqs.new < freqs.old)
 126                 pdata->set_voltage(idx);
 127
 128 out:
 129         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 130
 131         return ret;
 132 }
 133
 134 static int davinci_cpu_init(struct cpufreq_policy *policy)
 135 {
 136         int result = 0;
 137         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
 138         struct cpufreq_frequency_table *freq_table = pdata->freq_table;
 139
 140         if (policy->cpu != 0)
 141                 return -EINVAL;
 142
 143         /* Finish platform specific initialization */
 144         if (pdata->init) {
 145                 result = pdata->init();
 146                 if (result)
 147                         return result;
 148         }
 149
 150         policy->cur = policy->min = policy->max = davinci_getspeed(0);
 151
 152         if (freq_table) {
 153                 result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 154                 if (!result)
 155                         cpufreq_frequency_table_get_attr(freq_table,
 156                                                         policy->cpu);
 157         } else {
 158                 policy->cpuinfo.min_freq = policy->min;
 159                 policy->cpuinfo.max_freq = policy->max;
 160         }
 161
 162         policy->min = policy->cpuinfo.min_freq;
 163         policy->max = policy->cpuinfo.max_freq;
 164         policy->cur = davinci_getspeed(0);
 165
 166         /*
 167          * Time measurement across the target() function yields ~1500-1800us
 168          * time taken with no drivers on notification list.
 169          * Setting the latency to 2000 us to accommodate addition of drivers
 170          * to pre/post change notification list.
 171          */
 172         policy->cpuinfo.transition_latency = 2000 * 1000;
 173         return 0;
 174 }
 175
 176 static int davinci_cpu_exit(struct cpufreq_policy *policy)
 177 {
 178         cpufreq_frequency_table_put_attr(policy->cpu);
 179         return 0;
 180 }
 181
 182 static struct freq_attr *davinci_cpufreq_attr[] = {
 183         &cpufreq_freq_attr_scaling_available_freqs,
 184         NULL,
 185 };
 186
 187 static struct cpufreq_driver davinci_driver = {
 188         .flags          = CPUFREQ_STICKY,
 189         .verify         = davinci_verify_speed,
 190         .target         = davinci_target,
 191         .get            = davinci_getspeed,
 192         .init           = davinci_cpu_init,
 193         .exit           = davinci_cpu_exit,
 194         .name           = "davinci",
 195         .attr           = davinci_cpufreq_attr,
 196 };
 197
 198 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
 199 {
 200         struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
 201         struct clk *asyncclk;
 202
 203         if (!pdata)
 204                 return -EINVAL;
 205         if (!pdata->freq_table)
 206                 return -EINVAL;
 207
 208         cpufreq.dev = &pdev->dev;
 209
 210         cpufreq.armclk = clk_get(NULL, "arm");
 211         if (IS_ERR(cpufreq.armclk)) {
 212                 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
 213                 return PTR_ERR(cpufreq.armclk);
 214         }
 215
 216         asyncclk = clk_get(cpufreq.dev, "async");
 217         if (!IS_ERR(asyncclk)) {
 218                 cpufreq.asyncclk = asyncclk;
 219                 cpufreq.asyncrate = clk_get_rate(asyncclk);
 220         }
 221
 222         return cpufreq_register_driver(&davinci_driver);
 223 }
 224
 225 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
 226 {
 227         clk_put(cpufreq.armclk);
 228
 229         if (cpufreq.asyncclk)
 230                 clk_put(cpufreq.asyncclk);
 231
 232         return cpufreq_unregister_driver(&davinci_driver);
 233 }
 234
 235 static struct platform_driver davinci_cpufreq_driver = {
 236         .driver = {
 237                 .name    = "cpufreq-davinci",
 238                 .owner   = THIS_MODULE,
 239         },
 240         .remove = __exit_p(davinci_cpufreq_remove),
 241 };
 242
 243 static int __init davinci_cpufreq_init(void)
 244 {
 245         return platform_driver_probe(&davinci_cpufreq_driver,
 246                                                         davinci_cpufreq_probe);
 247 }
 248 late_initcall(davinci_cpufreq_init);
 249