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