linux/drivers/cpufreq/exynos-cpufreq.c
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   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 <mach/cpufreq.h>
  22
  23#include <plat/cpu.h>
  24
  25static struct exynos_dvfs_info *exynos_info;
  26
  27static struct regulator *arm_regulator;
  28static struct cpufreq_freqs freqs;
  29
  30static unsigned int locking_frequency;
  31static bool frequency_locked;
  32static DEFINE_MUTEX(cpufreq_lock);
  33
  34int exynos_verify_speed(struct cpufreq_policy *policy)
  35{
  36        return cpufreq_frequency_table_verify(policy,
  37                                              exynos_info->freq_table);
  38}
  39
  40unsigned int exynos_getspeed(unsigned int cpu)
  41{
  42        return clk_get_rate(exynos_info->cpu_clk) / 1000;
  43}
  44
  45static int exynos_target(struct cpufreq_policy *policy,
  46                          unsigned int target_freq,
  47                          unsigned int relation)
  48{
  49        unsigned int index, old_index;
  50        unsigned int arm_volt, safe_arm_volt = 0;
  51        int ret = 0;
  52        struct cpufreq_frequency_table *freq_table = exynos_info->freq_table;
  53        unsigned int *volt_table = exynos_info->volt_table;
  54        unsigned int mpll_freq_khz = exynos_info->mpll_freq_khz;
  55
  56        mutex_lock(&cpufreq_lock);
  57
  58        freqs.old = policy->cur;
  59
  60        if (frequency_locked && target_freq != locking_frequency) {
  61                ret = -EAGAIN;
  62                goto out;
  63        }
  64
  65        /*
  66         * The policy max have been changed so that we cannot get proper
  67         * old_index with cpufreq_frequency_table_target(). Thus, ignore
  68         * policy and get the index from the raw freqeuncy table.
  69         */
  70        for (old_index = 0;
  71                freq_table[old_index].frequency != CPUFREQ_TABLE_END;
  72                old_index++)
  73                if (freq_table[old_index].frequency == freqs.old)
  74                        break;
  75
  76        if (freq_table[old_index].frequency == CPUFREQ_TABLE_END) {
  77                ret = -EINVAL;
  78                goto out;
  79        }
  80
  81        if (cpufreq_frequency_table_target(policy, freq_table,
  82                                           target_freq, relation, &index)) {
  83                ret = -EINVAL;
  84                goto out;
  85        }
  86
  87        freqs.new = freq_table[index].frequency;
  88        freqs.cpu = policy->cpu;
  89
  90        /*
  91         * ARM clock source will be changed APLL to MPLL temporary
  92         * To support this level, need to control regulator for
  93         * required voltage level
  94         */
  95        if (exynos_info->need_apll_change != NULL) {
  96                if (exynos_info->need_apll_change(old_index, index) &&
  97                   (freq_table[index].frequency < mpll_freq_khz) &&
  98                   (freq_table[old_index].frequency < mpll_freq_khz))
  99                        safe_arm_volt = volt_table[exynos_info->pll_safe_idx];
 100        }
 101        arm_volt = volt_table[index];
 102
 103        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 104
 105        /* When the new frequency is higher than current frequency */
 106        if ((freqs.new > freqs.old) && !safe_arm_volt) {
 107                /* Firstly, voltage up to increase frequency */
 108                regulator_set_voltage(arm_regulator, arm_volt,
 109                                arm_volt);
 110        }
 111
 112        if (safe_arm_volt)
 113                regulator_set_voltage(arm_regulator, safe_arm_volt,
 114                                      safe_arm_volt);
 115        if (freqs.new != freqs.old)
 116                exynos_info->set_freq(old_index, index);
 117
 118        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 119
 120        /* When the new frequency is lower than current frequency */
 121        if ((freqs.new < freqs.old) ||
 122           ((freqs.new > freqs.old) && safe_arm_volt)) {
 123                /* down the voltage after frequency change */
 124                regulator_set_voltage(arm_regulator, arm_volt,
 125                                arm_volt);
 126        }
 127
 128out:
 129        mutex_unlock(&cpufreq_lock);
 130
 131        return ret;
 132}
 133
 134#ifdef CONFIG_PM
 135static int exynos_cpufreq_suspend(struct cpufreq_policy *policy)
 136{
 137        return 0;
 138}
 139
 140static int exynos_cpufreq_resume(struct cpufreq_policy *policy)
 141{
 142        return 0;
 143}
 144#endif
 145
 146/**
 147 * exynos_cpufreq_pm_notifier - block CPUFREQ's activities in suspend-resume
 148 *                      context
 149 * @notifier
 150 * @pm_event
 151 * @v
 152 *
 153 * While frequency_locked == true, target() ignores every frequency but
 154 * locking_frequency. The locking_frequency value is the initial frequency,
 155 * which is set by the bootloader. In order to eliminate possible
 156 * inconsistency in clock values, we save and restore frequencies during
 157 * suspend and resume and block CPUFREQ activities. Note that the standard
 158 * suspend/resume cannot be used as they are too deep (syscore_ops) for
 159 * regulator actions.
 160 */
 161static int exynos_cpufreq_pm_notifier(struct notifier_block *notifier,
 162                                       unsigned long pm_event, void *v)
 163{
 164        struct cpufreq_policy *policy = cpufreq_cpu_get(0); /* boot CPU */
 165        static unsigned int saved_frequency;
 166        unsigned int temp;
 167
 168        mutex_lock(&cpufreq_lock);
 169        switch (pm_event) {
 170        case PM_SUSPEND_PREPARE:
 171                if (frequency_locked)
 172                        goto out;
 173
 174                frequency_locked = true;
 175
 176                if (locking_frequency) {
 177                        saved_frequency = exynos_getspeed(0);
 178
 179                        mutex_unlock(&cpufreq_lock);
 180                        exynos_target(policy, locking_frequency,
 181                                      CPUFREQ_RELATION_H);
 182                        mutex_lock(&cpufreq_lock);
 183                }
 184                break;
 185
 186        case PM_POST_SUSPEND:
 187                if (saved_frequency) {
 188                        /*
 189                         * While frequency_locked, only locking_frequency
 190                         * is valid for target(). In order to use
 191                         * saved_frequency while keeping frequency_locked,
 192                         * we temporarly overwrite locking_frequency.
 193                         */
 194                        temp = locking_frequency;
 195                        locking_frequency = saved_frequency;
 196
 197                        mutex_unlock(&cpufreq_lock);
 198                        exynos_target(policy, locking_frequency,
 199                                      CPUFREQ_RELATION_H);
 200                        mutex_lock(&cpufreq_lock);
 201
 202                        locking_frequency = temp;
 203                }
 204                frequency_locked = false;
 205                break;
 206        }
 207out:
 208        mutex_unlock(&cpufreq_lock);
 209
 210        return NOTIFY_OK;
 211}
 212
 213static struct notifier_block exynos_cpufreq_nb = {
 214        .notifier_call = exynos_cpufreq_pm_notifier,
 215};
 216
 217static int exynos_cpufreq_cpu_init(struct cpufreq_policy *policy)
 218{
 219        policy->cur = policy->min = policy->max = exynos_getspeed(policy->cpu);
 220
 221        cpufreq_frequency_table_get_attr(exynos_info->freq_table, policy->cpu);
 222
 223        locking_frequency = exynos_getspeed(0);
 224
 225        /* set the transition latency value */
 226        policy->cpuinfo.transition_latency = 100000;
 227
 228        /*
 229         * EXYNOS4 multi-core processors has 2 cores
 230         * that the frequency cannot be set independently.
 231         * Each cpu is bound to the same speed.
 232         * So the affected cpu is all of the cpus.
 233         */
 234        if (num_online_cpus() == 1) {
 235                cpumask_copy(policy->related_cpus, cpu_possible_mask);
 236                cpumask_copy(policy->cpus, cpu_online_mask);
 237        } else {
 238                cpumask_setall(policy->cpus);
 239        }
 240
 241        return cpufreq_frequency_table_cpuinfo(policy, exynos_info->freq_table);
 242}
 243
 244static struct cpufreq_driver exynos_driver = {
 245        .flags          = CPUFREQ_STICKY,
 246        .verify         = exynos_verify_speed,
 247        .target         = exynos_target,
 248        .get            = exynos_getspeed,
 249        .init           = exynos_cpufreq_cpu_init,
 250        .name           = "exynos_cpufreq",
 251#ifdef CONFIG_PM
 252        .suspend        = exynos_cpufreq_suspend,
 253        .resume         = exynos_cpufreq_resume,
 254#endif
 255};
 256
 257static int __init exynos_cpufreq_init(void)
 258{
 259        int ret = -EINVAL;
 260
 261        exynos_info = kzalloc(sizeof(struct exynos_dvfs_info), GFP_KERNEL);
 262        if (!exynos_info)
 263                return -ENOMEM;
 264
 265        if (soc_is_exynos4210())
 266                ret = exynos4210_cpufreq_init(exynos_info);
 267        else if (soc_is_exynos4212() || soc_is_exynos4412())
 268                ret = exynos4x12_cpufreq_init(exynos_info);
 269        else if (soc_is_exynos5250())
 270                ret = exynos5250_cpufreq_init(exynos_info);
 271        else
 272                pr_err("%s: CPU type not found\n", __func__);
 273
 274        if (ret)
 275                goto err_vdd_arm;
 276
 277        if (exynos_info->set_freq == NULL) {
 278                pr_err("%s: No set_freq function (ERR)\n", __func__);
 279                goto err_vdd_arm;
 280        }
 281
 282        arm_regulator = regulator_get(NULL, "vdd_arm");
 283        if (IS_ERR(arm_regulator)) {
 284                pr_err("%s: failed to get resource vdd_arm\n", __func__);
 285                goto err_vdd_arm;
 286        }
 287
 288        register_pm_notifier(&exynos_cpufreq_nb);
 289
 290        if (cpufreq_register_driver(&exynos_driver)) {
 291                pr_err("%s: failed to register cpufreq driver\n", __func__);
 292                goto err_cpufreq;
 293        }
 294
 295        return 0;
 296err_cpufreq:
 297        unregister_pm_notifier(&exynos_cpufreq_nb);
 298
 299        if (!IS_ERR(arm_regulator))
 300                regulator_put(arm_regulator);
 301err_vdd_arm:
 302        kfree(exynos_info);
 303        pr_debug("%s: failed initialization\n", __func__);
 304        return -EINVAL;
 305}
 306late_initcall(exynos_cpufreq_init);
 307
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