drivers/cpufreq/omap-cpufreq.c

   1 /*
   2  *  CPU frequency scaling for OMAP using OPP information
   3  *
   4  *  Copyright (C) 2005 Nokia Corporation
   5  *  Written by Tony Lindgren <tony@atomide.com>
   6  *
   7  *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
   8  *
   9  * Copyright (C) 2007-2011 Texas Instruments, Inc.
  10  * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License version 2 as
  14  * published by the Free Software Foundation.
  15  */
  16 #include <linux/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/sched.h>
  19 #include <linux/cpufreq.h>
  20 #include <linux/delay.h>
  21 #include <linux/init.h>
  22 #include <linux/err.h>
  23 #include <linux/clk.h>
  24 #include <linux/io.h>
  25 #include <linux/opp.h>
  26 #include <linux/cpu.h>
  27 #include <linux/module.h>
  28 #include <linux/regulator/consumer.h>
  29
  30 #include <asm/smp_plat.h>
  31 #include <asm/cpu.h>
  32
  33 /* OPP tolerance in percentage */
  34 #define OPP_TOLERANCE   4
  35
  36 static struct cpufreq_frequency_table *freq_table;
  37 static atomic_t freq_table_users = ATOMIC_INIT(0);
  38 static struct clk *mpu_clk;
  39 static struct device *mpu_dev;
  40 static struct regulator *mpu_reg;
  41
  42 static int omap_verify_speed(struct cpufreq_policy *policy)
  43 {
  44         if (!freq_table)
  45                 return -EINVAL;
  46         return cpufreq_frequency_table_verify(policy, freq_table);
  47 }
  48
  49 static unsigned int omap_getspeed(unsigned int cpu)
  50 {
  51         unsigned long rate;
  52
  53         if (cpu >= NR_CPUS)
  54                 return 0;
  55
  56         rate = clk_get_rate(mpu_clk) / 1000;
  57         return rate;
  58 }
  59
  60 static int omap_target(struct cpufreq_policy *policy,
  61                        unsigned int target_freq,
  62                        unsigned int relation)
  63 {
  64         unsigned int i;
  65         int r, ret = 0;
  66         struct cpufreq_freqs freqs;
  67         struct opp *opp;
  68         unsigned long freq, volt = 0, volt_old = 0, tol = 0;
  69
  70         if (!freq_table) {
  71                 dev_err(mpu_dev, "%s: cpu%d: no freq table!\n", __func__,
  72                                 policy->cpu);
  73                 return -EINVAL;
  74         }
  75
  76         ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
  77                         relation, &i);
  78         if (ret) {
  79                 dev_dbg(mpu_dev, "%s: cpu%d: no freq match for %d(ret=%d)\n",
  80                         __func__, policy->cpu, target_freq, ret);
  81                 return ret;
  82         }
  83         freqs.new = freq_table[i].frequency;
  84         if (!freqs.new) {
  85                 dev_err(mpu_dev, "%s: cpu%d: no match for freq %d\n", __func__,
  86                         policy->cpu, target_freq);
  87                 return -EINVAL;
  88         }
  89
  90         freqs.old = omap_getspeed(policy->cpu);
  91         freqs.cpu = policy->cpu;
  92
  93         if (freqs.old == freqs.new && policy->cur == freqs.new)
  94                 return ret;
  95
  96         /* notifiers */
  97         for_each_cpu(i, policy->cpus) {
  98                 freqs.cpu = i;
  99                 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 100         }
 101
 102         freq = freqs.new * 1000;
 103         ret = clk_round_rate(mpu_clk, freq);
 104         if (IS_ERR_VALUE(ret)) {
 105                 dev_warn(mpu_dev,
 106                          "CPUfreq: Cannot find matching frequency for %lu\n",
 107                          freq);
 108                 return ret;
 109         }
 110         freq = ret;
 111
 112         if (mpu_reg) {
 113                 rcu_read_lock();
 114                 opp = opp_find_freq_ceil(mpu_dev, &freq);
 115                 if (IS_ERR(opp)) {
 116                         rcu_read_unlock();
 117                         dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
 118                                 __func__, freqs.new);
 119                         return -EINVAL;
 120                 }
 121                 volt = opp_get_voltage(opp);
 122                 rcu_read_unlock();
 123                 tol = volt * OPP_TOLERANCE / 100;
 124                 volt_old = regulator_get_voltage(mpu_reg);
 125         }
 126
 127         dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
 128                 freqs.old / 1000, volt_old ? volt_old / 1000 : -1,
 129                 freqs.new / 1000, volt ? volt / 1000 : -1);
 130
 131         /* scaling up?  scale voltage before frequency */
 132         if (mpu_reg && (freqs.new > freqs.old)) {
 133                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
 134                 if (r < 0) {
 135                         dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
 136                                  __func__);
 137                         freqs.new = freqs.old;
 138                         goto done;
 139                 }
 140         }
 141
 142         ret = clk_set_rate(mpu_clk, freqs.new * 1000);
 143
 144         /* scaling down?  scale voltage after frequency */
 145         if (mpu_reg && (freqs.new < freqs.old)) {
 146                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
 147                 if (r < 0) {
 148                         dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
 149                                  __func__);
 150                         ret = clk_set_rate(mpu_clk, freqs.old * 1000);
 151                         freqs.new = freqs.old;
 152                         goto done;
 153                 }
 154         }
 155
 156         freqs.new = omap_getspeed(policy->cpu);
 157
 158 done:
 159         /* notifiers */
 160         for_each_cpu(i, policy->cpus) {
 161                 freqs.cpu = i;
 162                 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 163         }
 164
 165         return ret;
 166 }
 167
 168 static inline void freq_table_free(void)
 169 {
 170         if (atomic_dec_and_test(&freq_table_users))
 171                 opp_free_cpufreq_table(mpu_dev, &freq_table);
 172 }
 173
 174 static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy)
 175 {
 176         int result = 0;
 177
 178         mpu_clk = clk_get(NULL, "cpufreq_ck");
 179         if (IS_ERR(mpu_clk))
 180                 return PTR_ERR(mpu_clk);
 181
 182         if (policy->cpu >= NR_CPUS) {
 183                 result = -EINVAL;
 184                 goto fail_ck;
 185         }
 186
 187         policy->cur = policy->min = policy->max = omap_getspeed(policy->cpu);
 188
 189         if (!freq_table)
 190                 result = opp_init_cpufreq_table(mpu_dev, &freq_table);
 191
 192         if (result) {
 193                 dev_err(mpu_dev, "%s: cpu%d: failed creating freq table[%d]\n",
 194                                 __func__, policy->cpu, result);
 195                 goto fail_ck;
 196         }
 197
 198         atomic_inc_return(&freq_table_users);
 199
 200         result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 201         if (result)
 202                 goto fail_table;
 203
 204         cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 205
 206         policy->min = policy->cpuinfo.min_freq;
 207         policy->max = policy->cpuinfo.max_freq;
 208         policy->cur = omap_getspeed(policy->cpu);
 209
 210         /*
 211          * On OMAP SMP configuartion, both processors share the voltage
 212          * and clock. So both CPUs needs to be scaled together and hence
 213          * needs software co-ordination. Use cpufreq affected_cpus
 214          * interface to handle this scenario. Additional is_smp() check
 215          * is to keep SMP_ON_UP build working.
 216          */
 217         if (is_smp())
 218                 cpumask_setall(policy->cpus);
 219
 220         /* FIXME: what's the actual transition time? */
 221         policy->cpuinfo.transition_latency = 300 * 1000;
 222
 223         return 0;
 224
 225 fail_table:
 226         freq_table_free();
 227 fail_ck:
 228         clk_put(mpu_clk);
 229         return result;
 230 }
 231
 232 static int omap_cpu_exit(struct cpufreq_policy *policy)
 233 {
 234         freq_table_free();
 235         clk_put(mpu_clk);
 236         return 0;
 237 }
 238
 239 static struct freq_attr *omap_cpufreq_attr[] = {
 240         &cpufreq_freq_attr_scaling_available_freqs,
 241         NULL,
 242 };
 243
 244 static struct cpufreq_driver omap_driver = {
 245         .flags          = CPUFREQ_STICKY,
 246         .verify         = omap_verify_speed,
 247         .target         = omap_target,
 248         .get            = omap_getspeed,
 249         .init           = omap_cpu_init,
 250         .exit           = omap_cpu_exit,
 251         .name           = "omap",
 252         .attr           = omap_cpufreq_attr,
 253 };
 254
 255 static int __init omap_cpufreq_init(void)
 256 {
 257         mpu_dev = get_cpu_device(0);
 258         if (!mpu_dev) {
 259                 pr_warning("%s: unable to get the mpu device\n", __func__);
 260                 return -EINVAL;
 261         }
 262
 263         mpu_reg = regulator_get(mpu_dev, "vcc");
 264         if (IS_ERR(mpu_reg)) {
 265                 pr_warning("%s: unable to get MPU regulator\n", __func__);
 266                 mpu_reg = NULL;
 267         } else {
 268                 /*
 269                  * Ensure physical regulator is present.
 270                  * (e.g. could be dummy regulator.)
 271                  */
 272                 if (regulator_get_voltage(mpu_reg) < 0) {
 273                         pr_warn("%s: physical regulator not present for MPU\n",
 274                                 __func__);
 275                         regulator_put(mpu_reg);
 276                         mpu_reg = NULL;
 277                 }
 278         }
 279
 280         return cpufreq_register_driver(&omap_driver);
 281 }
 282
 283 static void __exit omap_cpufreq_exit(void)
 284 {
 285         cpufreq_unregister_driver(&omap_driver);
 286 }
 287
 288 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
 289 MODULE_LICENSE("GPL");
 290 module_init(omap_cpufreq_init);
 291 module_exit(omap_cpufreq_exit);