drivers/cpufreq/exynos-cpufreq.c

   1 /*
   2  * Copyright (c) 2010-2011 Samsung Electronics Co., Ltd.
   3  *              http://www.samsung.com
   4  *
   5  * EXYNOS - CPU frequency scaling support for EXYNOS series
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10 */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/err.h>
  14 #include <linux/clk.h>
  15 #include <linux/io.h>
  16 #include <linux/slab.h>
  17 #include <linux/regulator/consumer.h>
  18 #include <linux/cpufreq.h>
  19 #include <linux/suspend.h>
  20
  21 #include <plat/cpu.h>
  22
  23 #include "exynos-cpufreq.h"
  24
  25 static struct exynos_dvfs_info *exynos_info;
  26
  27 static struct regulator *arm_regulator;
  28 static struct cpufreq_freqs freqs;
  29
  30 static unsigned int locking_frequency;
  31 static bool frequency_locked;
  32 static DEFINE_MUTEX(cpufreq_lock);
  33
  34 static unsigned int exynos_getspeed(unsigned int cpu)
  35 {
  36         return clk_get_rate(exynos_info->cpu_clk) / 1000;
  37 }
  38
  39 static int exynos_cpufreq_get_index(unsigned int freq)
  40 {
  41         struct cpufreq_frequency_table *freq_table = exynos_info->freq_table;
  42         int index;
  43
  44         for (index = 0;
  45                 freq_table[index].frequency != CPUFREQ_TABLE_END; index++)
  46                 if (freq_table[index].frequency == freq)
  47                         break;
  48
  49         if (freq_table[index].frequency == CPUFREQ_TABLE_END)
  50                 return -EINVAL;
  51
  52         return index;
  53 }
  54
  55 static int exynos_cpufreq_scale(unsigned int target_freq)
  56 {
  57         struct cpufreq_frequency_table *freq_table = exynos_info->freq_table;
  58         unsigned int *volt_table = exynos_info->volt_table;
  59         struct cpufreq_policy *policy = cpufreq_cpu_get(0);
  60         unsigned int arm_volt, safe_arm_volt = 0;
  61         unsigned int mpll_freq_khz = exynos_info->mpll_freq_khz;
  62         int index, old_index;
  63         int ret = 0;
  64
  65         freqs.old = policy->cur;
  66         freqs.new = target_freq;
  67
  68         if (freqs.new == freqs.old)
  69                 goto out;
  70
  71         /*
  72          * The policy max have been changed so that we cannot get proper
  73          * old_index with cpufreq_frequency_table_target(). Thus, ignore
  74          * policy and get the index from the raw frequency table.
  75          */
  76         old_index = exynos_cpufreq_get_index(freqs.old);
  77         if (old_index < 0) {
  78                 ret = old_index;
  79                 goto out;
  80         }
  81
  82         index = exynos_cpufreq_get_index(target_freq);
  83         if (index < 0) {
  84                 ret = index;
  85                 goto out;
  86         }
  87
  88         /*
  89          * ARM clock source will be changed APLL to MPLL temporary
  90          * To support this level, need to control regulator for
  91          * required voltage level
  92          */
  93         if (exynos_info->need_apll_change != NULL) {
  94                 if (exynos_info->need_apll_change(old_index, index) &&
  95                    (freq_table[index].frequency < mpll_freq_khz) &&
  96                    (freq_table[old_index].frequency < mpll_freq_khz))
  97                         safe_arm_volt = volt_table[exynos_info->pll_safe_idx];
  98         }
  99         arm_volt = volt_table[index];
 100
 101         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
 102
 103         /* When the new frequency is higher than current frequency */
 104         if ((freqs.new > freqs.old) && !safe_arm_volt) {
 105                 /* Firstly, voltage up to increase frequency */
 106                 ret = regulator_set_voltage(arm_regulator, arm_volt, arm_volt);
 107                 if (ret) {
 108                         pr_err("%s: failed to set cpu voltage to %d\n",
 109                                 __func__, arm_volt);
 110                         freqs.new = freqs.old;
 111                         goto post_notify;
 112                 }
 113         }
 114
 115         if (safe_arm_volt) {
 116                 ret = regulator_set_voltage(arm_regulator, safe_arm_volt,
 117                                       safe_arm_volt);
 118                 if (ret) {
 119                         pr_err("%s: failed to set cpu voltage to %d\n",
 120                                 __func__, safe_arm_volt);
 121                         freqs.new = freqs.old;
 122                         goto post_notify;
 123                 }
 124         }
 125
 126         exynos_info->set_freq(old_index, index);
 127
 128 post_notify:
 129         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 130
 131         if (ret)
 132                 goto out;
 133
 134         /* When the new frequency is lower than current frequency */
 135         if ((freqs.new < freqs.old) ||
 136            ((freqs.new > freqs.old) && safe_arm_volt)) {
 137                 /* down the voltage after frequency change */
 138                 ret = regulator_set_voltage(arm_regulator, arm_volt,
 139                                 arm_volt);
 140                 if (ret) {
 141                         pr_err("%s: failed to set cpu voltage to %d\n",
 142                                 __func__, arm_volt);
 143                         goto out;
 144                 }
 145         }
 146
 147 out:
 148
 149         cpufreq_cpu_put(policy);
 150
 151         return ret;
 152 }
 153
 154 static int exynos_target(struct cpufreq_policy *policy,
 155                           unsigned int target_freq,
 156                           unsigned int relation)
 157 {
 158         struct cpufreq_frequency_table *freq_table = exynos_info->freq_table;
 159         unsigned int index;
 160         unsigned int new_freq;
 161         int ret = 0;
 162
 163         mutex_lock(&cpufreq_lock);
 164
 165         if (frequency_locked)
 166                 goto out;
 167
 168         if (cpufreq_frequency_table_target(policy, freq_table,
 169                                            target_freq, relation, &index)) {
 170                 ret = -EINVAL;
 171                 goto out;
 172         }
 173
 174         new_freq = freq_table[index].frequency;
 175
 176         ret = exynos_cpufreq_scale(new_freq);
 177
 178 out:
 179         mutex_unlock(&cpufreq_lock);
 180
 181         return ret;
 182 }
 183
 184 #ifdef CONFIG_PM
 185 static int exynos_cpufreq_suspend(struct cpufreq_policy *policy)
 186 {
 187         return 0;
 188 }
 189
 190 static int exynos_cpufreq_resume(struct cpufreq_policy *policy)
 191 {
 192         return 0;
 193 }
 194 #endif
 195
 196 /**
 197  * exynos_cpufreq_pm_notifier - block CPUFREQ's activities in suspend-resume
 198  *                      context
 199  * @notifier
 200  * @pm_event
 201  * @v
 202  *
 203  * While frequency_locked == true, target() ignores every frequency but
 204  * locking_frequency. The locking_frequency value is the initial frequency,
 205  * which is set by the bootloader. In order to eliminate possible
 206  * inconsistency in clock values, we save and restore frequencies during
 207  * suspend and resume and block CPUFREQ activities. Note that the standard
 208  * suspend/resume cannot be used as they are too deep (syscore_ops) for
 209  * regulator actions.
 210  */
 211 static int exynos_cpufreq_pm_notifier(struct notifier_block *notifier,
 212                                        unsigned long pm_event, void *v)
 213 {
 214         int ret;
 215
 216         switch (pm_event) {
 217         case PM_SUSPEND_PREPARE:
 218                 mutex_lock(&cpufreq_lock);
 219                 frequency_locked = true;
 220                 mutex_unlock(&cpufreq_lock);
 221
 222                 ret = exynos_cpufreq_scale(locking_frequency);
 223                 if (ret < 0)
 224                         return NOTIFY_BAD;
 225
 226                 break;
 227
 228         case PM_POST_SUSPEND:
 229                 mutex_lock(&cpufreq_lock);
 230                 frequency_locked = false;
 231                 mutex_unlock(&cpufreq_lock);
 232                 break;
 233         }
 234
 235         return NOTIFY_OK;
 236 }
 237
 238 static struct notifier_block exynos_cpufreq_nb = {
 239         .notifier_call = exynos_cpufreq_pm_notifier,
 240 };
 241
 242 static int exynos_cpufreq_cpu_init(struct cpufreq_policy *policy)
 243 {
 244         return cpufreq_generic_init(policy, exynos_info->freq_table, 100000);
 245 }
 246
 247 static struct cpufreq_driver exynos_driver = {
 248         .flags          = CPUFREQ_STICKY,
 249         .verify         = cpufreq_generic_frequency_table_verify,
 250         .target         = exynos_target,
 251         .get            = exynos_getspeed,
 252         .init           = exynos_cpufreq_cpu_init,
 253         .exit           = cpufreq_generic_exit,
 254         .name           = "exynos_cpufreq",
 255         .attr           = cpufreq_generic_attr,
 256 #ifdef CONFIG_PM
 257         .suspend        = exynos_cpufreq_suspend,
 258         .resume         = exynos_cpufreq_resume,
 259 #endif
 260 };
 261
 262 static int __init exynos_cpufreq_init(void)
 263 {
 264         int ret = -EINVAL;
 265
 266         exynos_info = kzalloc(sizeof(*exynos_info), GFP_KERNEL);
 267         if (!exynos_info)
 268                 return -ENOMEM;
 269
 270         if (soc_is_exynos4210())
 271                 ret = exynos4210_cpufreq_init(exynos_info);
 272         else if (soc_is_exynos4212() || soc_is_exynos4412())
 273                 ret = exynos4x12_cpufreq_init(exynos_info);
 274         else if (soc_is_exynos5250())
 275                 ret = exynos5250_cpufreq_init(exynos_info);
 276         else
 277                 return 0;
 278
 279         if (ret)
 280                 goto err_vdd_arm;
 281
 282         if (exynos_info->set_freq == NULL) {
 283                 pr_err("%s: No set_freq function (ERR)\n", __func__);
 284                 goto err_vdd_arm;
 285         }
 286
 287         arm_regulator = regulator_get(NULL, "vdd_arm");
 288         if (IS_ERR(arm_regulator)) {
 289                 pr_err("%s: failed to get resource vdd_arm\n", __func__);
 290                 goto err_vdd_arm;
 291         }
 292
 293         locking_frequency = exynos_getspeed(0);
 294
 295         register_pm_notifier(&exynos_cpufreq_nb);
 296
 297         if (cpufreq_register_driver(&exynos_driver)) {
 298                 pr_err("%s: failed to register cpufreq driver\n", __func__);
 299                 goto err_cpufreq;
 300         }
 301
 302         return 0;
 303 err_cpufreq:
 304         unregister_pm_notifier(&exynos_cpufreq_nb);
 305
 306         regulator_put(arm_regulator);
 307 err_vdd_arm:
 308         kfree(exynos_info);
 309         return -EINVAL;
 310 }
 311 late_initcall(exynos_cpufreq_init);