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

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