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         cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER,
  98                         dev_driver_string(cpufreq.dev),
  99                         "transition: %u --> %u\n", freqs.old, freqs.new);
 100
 101         ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
 102                                                 freqs.new, relation, &idx);
 103         if (ret)
 104                 return -EINVAL;
 105
 106         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 107
 108         /* if moving to higher frequency, up the voltage beforehand */
 109         if (pdata->set_voltage && freqs.new > freqs.old) {
 110                 ret = pdata->set_voltage(idx);
 111                 if (ret)
 112                         goto out;
 113         }
 114
 115         ret = clk_set_rate(armclk, idx);
 116         if (ret)
 117                 goto out;
 118
 119         if (cpufreq.asyncclk) {
 120                 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
 121                 if (ret)
 122                         goto out;
 123         }
 124
 125         /* if moving to lower freq, lower the voltage after lowering freq */
 126         if (pdata->set_voltage && freqs.new < freqs.old)
 127                 pdata->set_voltage(idx);
 128
 129 out:
 130         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 131
 132         return ret;
 133 }
 134
 135 static int davinci_cpu_init(struct cpufreq_policy *policy)
 136 {
 137         int result = 0;
 138         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
 139         struct cpufreq_frequency_table *freq_table = pdata->freq_table;
 140
 141         if (policy->cpu != 0)
 142                 return -EINVAL;
 143
 144         /* Finish platform specific initialization */
 145         if (pdata->init) {
 146                 result = pdata->init();
 147                 if (result)
 148                         return result;
 149         }
 150
 151         policy->cur = policy->min = policy->max = davinci_getspeed(0);
 152
 153         if (freq_table) {
 154                 result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 155                 if (!result)
 156                         cpufreq_frequency_table_get_attr(freq_table,
 157                                                         policy->cpu);
 158         } else {
 159                 policy->cpuinfo.min_freq = policy->min;
 160                 policy->cpuinfo.max_freq = policy->max;
 161         }
 162
 163         policy->min = policy->cpuinfo.min_freq;
 164         policy->max = policy->cpuinfo.max_freq;
 165         policy->cur = davinci_getspeed(0);
 166
 167         /*
 168          * Time measurement across the target() function yields ~1500-1800us
 169          * time taken with no drivers on notification list.
 170          * Setting the latency to 2000 us to accommodate addition of drivers
 171          * to pre/post change notification list.
 172          */
 173         policy->cpuinfo.transition_latency = 2000 * 1000;
 174         return 0;
 175 }
 176
 177 static int davinci_cpu_exit(struct cpufreq_policy *policy)
 178 {
 179         cpufreq_frequency_table_put_attr(policy->cpu);
 180         return 0;
 181 }
 182
 183 static struct freq_attr *davinci_cpufreq_attr[] = {
 184         &cpufreq_freq_attr_scaling_available_freqs,
 185         NULL,
 186 };
 187
 188 static struct cpufreq_driver davinci_driver = {
 189         .flags          = CPUFREQ_STICKY,
 190         .verify         = davinci_verify_speed,
 191         .target         = davinci_target,
 192         .get            = davinci_getspeed,
 193         .init           = davinci_cpu_init,
 194         .exit           = davinci_cpu_exit,
 195         .name           = "davinci",
 196         .attr           = davinci_cpufreq_attr,
 197 };
 198
 199 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
 200 {
 201         struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
 202         struct clk *asyncclk;
 203
 204         if (!pdata)
 205                 return -EINVAL;
 206         if (!pdata->freq_table)
 207                 return -EINVAL;
 208
 209         cpufreq.dev = &pdev->dev;
 210
 211         cpufreq.armclk = clk_get(NULL, "arm");
 212         if (IS_ERR(cpufreq.armclk)) {
 213                 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
 214                 return PTR_ERR(cpufreq.armclk);
 215         }
 216
 217         asyncclk = clk_get(cpufreq.dev, "async");
 218         if (!IS_ERR(asyncclk)) {
 219                 cpufreq.asyncclk = asyncclk;
 220                 cpufreq.asyncrate = clk_get_rate(asyncclk);
 221         }
 222
 223         return cpufreq_register_driver(&davinci_driver);
 224 }
 225
 226 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
 227 {
 228         clk_put(cpufreq.armclk);
 229
 230         if (cpufreq.asyncclk)
 231                 clk_put(cpufreq.asyncclk);
 232
 233         return cpufreq_unregister_driver(&davinci_driver);
 234 }
 235
 236 static struct platform_driver davinci_cpufreq_driver = {
 237         .driver = {
 238                 .name    = "cpufreq-davinci",
 239                 .owner   = THIS_MODULE,
 240         },
 241         .remove = __exit_p(davinci_cpufreq_remove),
 242 };
 243
 244 static int __init davinci_cpufreq_init(void)
 245 {
 246         return platform_driver_probe(&davinci_cpufreq_driver,
 247                                                         davinci_cpufreq_probe);
 248 }
 249 late_initcall(davinci_cpufreq_init);
 250