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 <plat/cpu.h>
  22
  23#include "exynos-cpufreq.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
  34static int exynos_verify_speed(struct cpufreq_policy *policy)
  35{
  36        return cpufreq_frequency_table_verify(policy,
  37                                              exynos_info->freq_table);
  38}
  39
  40static unsigned int exynos_getspeed(unsigned int cpu)
  41{
  42        return clk_get_rate(exynos_info->cpu_clk) / 1000;
  43}
  44
  45static int exynos_cpufreq_get_index(unsigned int freq)
  46{
  47        struct cpufreq_frequency_table *freq_table = exynos_info->freq_table;
  48        int index;
  49
  50        for (index = 0;
  51                freq_table[index].frequency != CPUFREQ_TABLE_END; index++)
  52                if (freq_table[index].frequency == freq)
  53                        break;
  54
  55        if (freq_table[index].frequency == CPUFREQ_TABLE_END)
  56                return -EINVAL;
  57
  58        return index;
  59}
  60
  61static int exynos_cpufreq_scale(unsigned int target_freq)
  62{
  63        struct cpufreq_frequency_table *freq_table = exynos_info->freq_table;
  64        unsigned int *volt_table = exynos_info->volt_table;
  65        struct cpufreq_policy *policy = cpufreq_cpu_get(0);
  66        unsigned int arm_volt, safe_arm_volt = 0;
  67        unsigned int mpll_freq_khz = exynos_info->mpll_freq_khz;
  68        int index, old_index;
  69        int ret = 0;
  70
  71        freqs.old = policy->cur;
  72        freqs.new = target_freq;
  73
  74        if (freqs.new == freqs.old)
  75                goto out;
  76
  77        /*
  78         * The policy max have been changed so that we cannot get proper
  79         * old_index with cpufreq_frequency_table_target(). Thus, ignore
  80         * policy and get the index from the raw freqeuncy table.
  81         */
  82        old_index = exynos_cpufreq_get_index(freqs.old);
  83        if (old_index < 0) {
  84                ret = old_index;
  85                goto out;
  86        }
  87
  88        index = exynos_cpufreq_get_index(target_freq);
  89        if (index < 0) {
  90                ret = index;
  91                goto out;
  92        }
  93
  94        /*
  95         * ARM clock source will be changed APLL to MPLL temporary
  96         * To support this level, need to control regulator for
  97         * required voltage level
  98         */
  99        if (exynos_info->need_apll_change != NULL) {
 100                if (exynos_info->need_apll_change(old_index, index) &&
 101                   (freq_table[index].frequency < mpll_freq_khz) &&
 102                   (freq_table[old_index].frequency < mpll_freq_khz))
 103                        safe_arm_volt = volt_table[exynos_info->pll_safe_idx];
 104        }
 105        arm_volt = volt_table[index];
 106
 107        cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
 108
 109        /* When the new frequency is higher than current frequency */
 110        if ((freqs.new > freqs.old) && !safe_arm_volt) {
 111                /* Firstly, voltage up to increase frequency */
 112                ret = regulator_set_voltage(arm_regulator, arm_volt, arm_volt);
 113                if (ret) {
 114                        pr_err("%s: failed to set cpu voltage to %d\n",
 115                                __func__, arm_volt);
 116                        freqs.new = freqs.old;
 117                        goto post_notify;
 118                }
 119        }
 120
 121        if (safe_arm_volt) {
 122                ret = regulator_set_voltage(arm_regulator, safe_arm_volt,
 123                                      safe_arm_volt);
 124                if (ret) {
 125                        pr_err("%s: failed to set cpu voltage to %d\n",
 126                                __func__, safe_arm_volt);
 127                        freqs.new = freqs.old;
 128                        goto post_notify;
 129                }
 130        }
 131
 132        exynos_info->set_freq(old_index, index);
 133
 134post_notify:
 135        cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 136
 137        if (ret)
 138                goto out;
 139
 140        /* When the new frequency is lower than current frequency */
 141        if ((freqs.new < freqs.old) ||
 142           ((freqs.new > freqs.old) && safe_arm_volt)) {
 143                /* down the voltage after frequency change */
 144                regulator_set_voltage(arm_regulator, arm_volt,
 145                                arm_volt);
 146                if (ret) {
 147                        pr_err("%s: failed to set cpu voltage to %d\n",
 148                                __func__, arm_volt);
 149                        goto out;
 150                }
 151        }
 152
 153out:
 154
 155        cpufreq_cpu_put(policy);
 156
 157        return ret;
 158}
 159
 160static int exynos_target(struct cpufreq_policy *policy,
 161                          unsigned int target_freq,
 162                          unsigned int relation)
 163{
 164        struct cpufreq_frequency_table *freq_table = exynos_info->freq_table;
 165        unsigned int index;
 166        unsigned int new_freq;
 167        int ret = 0;
 168
 169        mutex_lock(&cpufreq_lock);
 170
 171        if (frequency_locked)
 172                goto out;
 173
 174        if (cpufreq_frequency_table_target(policy, freq_table,
 175                                           target_freq, relation, &index)) {
 176                ret = -EINVAL;
 177                goto out;
 178        }
 179
 180        new_freq = freq_table[index].frequency;
 181
 182        ret = exynos_cpufreq_scale(new_freq);
 183
 184out:
 185        mutex_unlock(&cpufreq_lock);
 186
 187        return ret;
 188}
 189
 190#ifdef CONFIG_PM
 191static int exynos_cpufreq_suspend(struct cpufreq_policy *policy)
 192{
 193        return 0;
 194}
 195
 196static int exynos_cpufreq_resume(struct cpufreq_policy *policy)
 197{
 198        return 0;
 199}
 200#endif
 201
 202/**
 203 * exynos_cpufreq_pm_notifier - block CPUFREQ's activities in suspend-resume
 204 *                      context
 205 * @notifier
 206 * @pm_event
 207 * @v
 208 *
 209 * While frequency_locked == true, target() ignores every frequency but
 210 * locking_frequency. The locking_frequency value is the initial frequency,
 211 * which is set by the bootloader. In order to eliminate possible
 212 * inconsistency in clock values, we save and restore frequencies during
 213 * suspend and resume and block CPUFREQ activities. Note that the standard
 214 * suspend/resume cannot be used as they are too deep (syscore_ops) for
 215 * regulator actions.
 216 */
 217static int exynos_cpufreq_pm_notifier(struct notifier_block *notifier,
 218                                       unsigned long pm_event, void *v)
 219{
 220        int ret;
 221
 222        switch (pm_event) {
 223        case PM_SUSPEND_PREPARE:
 224                mutex_lock(&cpufreq_lock);
 225                frequency_locked = true;
 226                mutex_unlock(&cpufreq_lock);
 227
 228                ret = exynos_cpufreq_scale(locking_frequency);
 229                if (ret < 0)
 230                        return NOTIFY_BAD;
 231
 232                break;
 233
 234        case PM_POST_SUSPEND:
 235                mutex_lock(&cpufreq_lock);
 236                frequency_locked = false;
 237                mutex_unlock(&cpufreq_lock);
 238                break;
 239        }
 240
 241        return NOTIFY_OK;
 242}
 243
 244static struct notifier_block exynos_cpufreq_nb = {
 245        .notifier_call = exynos_cpufreq_pm_notifier,
 246};
 247
 248static int exynos_cpufreq_cpu_init(struct cpufreq_policy *policy)
 249{
 250        policy->cur = policy->min = policy->max = exynos_getspeed(policy->cpu);
 251
 252        cpufreq_frequency_table_get_attr(exynos_info->freq_table, policy->cpu);
 253
 254        /* set the transition latency value */
 255        policy->cpuinfo.transition_latency = 100000;
 256
 257        cpumask_setall(policy->cpus);
 258
 259        return cpufreq_frequency_table_cpuinfo(policy, exynos_info->freq_table);
 260}
 261
 262static int exynos_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 263{
 264        cpufreq_frequency_table_put_attr(policy->cpu);
 265        return 0;
 266}
 267
 268static struct freq_attr *exynos_cpufreq_attr[] = {
 269        &cpufreq_freq_attr_scaling_available_freqs,
 270        NULL,
 271};
 272
 273static struct cpufreq_driver exynos_driver = {
 274        .flags          = CPUFREQ_STICKY,
 275        .verify         = exynos_verify_speed,
 276        .target         = exynos_target,
 277        .get            = exynos_getspeed,
 278        .init           = exynos_cpufreq_cpu_init,
 279        .exit           = exynos_cpufreq_cpu_exit,
 280        .name           = "exynos_cpufreq",
 281        .attr           = exynos_cpufreq_attr,
 282#ifdef CONFIG_PM
 283        .suspend        = exynos_cpufreq_suspend,
 284        .resume         = exynos_cpufreq_resume,
 285#endif
 286};
 287
 288static int __init exynos_cpufreq_init(void)
 289{
 290        int ret = -EINVAL;
 291
 292        exynos_info = kzalloc(sizeof(struct exynos_dvfs_info), GFP_KERNEL);
 293        if (!exynos_info)
 294                return -ENOMEM;
 295
 296        if (soc_is_exynos4210())
 297                ret = exynos4210_cpufreq_init(exynos_info);
 298        else if (soc_is_exynos4212() || soc_is_exynos4412())
 299                ret = exynos4x12_cpufreq_init(exynos_info);
 300        else if (soc_is_exynos5250())
 301                ret = exynos5250_cpufreq_init(exynos_info);
 302        else
 303                return 0;
 304
 305        if (ret)
 306                goto err_vdd_arm;
 307
 308        if (exynos_info->set_freq == NULL) {
 309                pr_err("%s: No set_freq function (ERR)\n", __func__);
 310                goto err_vdd_arm;
 311        }
 312
 313        arm_regulator = regulator_get(NULL, "vdd_arm");
 314        if (IS_ERR(arm_regulator)) {
 315                pr_err("%s: failed to get resource vdd_arm\n", __func__);
 316                goto err_vdd_arm;
 317        }
 318
 319        locking_frequency = exynos_getspeed(0);
 320
 321        register_pm_notifier(&exynos_cpufreq_nb);
 322
 323        if (cpufreq_register_driver(&exynos_driver)) {
 324                pr_err("%s: failed to register cpufreq driver\n", __func__);
 325                goto err_cpufreq;
 326        }
 327
 328        return 0;
 329err_cpufreq:
 330        unregister_pm_notifier(&exynos_cpufreq_nb);
 331
 332        regulator_put(arm_regulator);
 333err_vdd_arm:
 334        kfree(exynos_info);
 335        pr_debug("%s: failed initialization\n", __func__);
 336        return -EINVAL;
 337}
 338late_initcall(exynos_cpufreq_init);
 339
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