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                 opp = opp_find_freq_ceil(mpu_dev, &freq);
 114                 if (IS_ERR(opp)) {
 115                         dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
 116                                 __func__, freqs.new);
 117                         return -EINVAL;
 118                 }
 119                 volt = opp_get_voltage(opp);
 120                 tol = volt * OPP_TOLERANCE / 100;
 121                 volt_old = regulator_get_voltage(mpu_reg);
 122         }
 123
 124         dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
 125                 freqs.old / 1000, volt_old ? volt_old / 1000 : -1,
 126                 freqs.new / 1000, volt ? volt / 1000 : -1);
 127
 128         /* scaling up?  scale voltage before frequency */
 129         if (mpu_reg && (freqs.new > freqs.old)) {
 130                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
 131                 if (r < 0) {
 132                         dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
 133                                  __func__);
 134                         freqs.new = freqs.old;
 135                         goto done;
 136                 }
 137         }
 138
 139         ret = clk_set_rate(mpu_clk, freqs.new * 1000);
 140
 141         /* scaling down?  scale voltage after frequency */
 142         if (mpu_reg && (freqs.new < freqs.old)) {
 143                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
 144                 if (r < 0) {
 145                         dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
 146                                  __func__);
 147                         ret = clk_set_rate(mpu_clk, freqs.old * 1000);
 148                         freqs.new = freqs.old;
 149                         goto done;
 150                 }
 151         }
 152
 153         freqs.new = omap_getspeed(policy->cpu);
 154
 155 done:
 156         /* notifiers */
 157         for_each_cpu(i, policy->cpus) {
 158                 freqs.cpu = i;
 159                 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 160         }
 161
 162         return ret;
 163 }
 164
 165 static inline void freq_table_free(void)
 166 {
 167         if (atomic_dec_and_test(&freq_table_users))
 168                 opp_free_cpufreq_table(mpu_dev, &freq_table);
 169 }
 170
 171 static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy)
 172 {
 173         int result = 0;
 174
 175         mpu_clk = clk_get(NULL, "cpufreq_ck");
 176         if (IS_ERR(mpu_clk))
 177                 return PTR_ERR(mpu_clk);
 178
 179         if (policy->cpu >= NR_CPUS) {
 180                 result = -EINVAL;
 181                 goto fail_ck;
 182         }
 183
 184         policy->cur = policy->min = policy->max = omap_getspeed(policy->cpu);
 185
 186         if (!freq_table)
 187                 result = opp_init_cpufreq_table(mpu_dev, &freq_table);
 188
 189         if (result) {
 190                 dev_err(mpu_dev, "%s: cpu%d: failed creating freq table[%d]\n",
 191                                 __func__, policy->cpu, result);
 192                 goto fail_ck;
 193         }
 194
 195         atomic_inc_return(&freq_table_users);
 196
 197         result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 198         if (result)
 199                 goto fail_table;
 200
 201         cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 202
 203         policy->min = policy->cpuinfo.min_freq;
 204         policy->max = policy->cpuinfo.max_freq;
 205         policy->cur = omap_getspeed(policy->cpu);
 206
 207         /*
 208          * On OMAP SMP configuartion, both processors share the voltage
 209          * and clock. So both CPUs needs to be scaled together and hence
 210          * needs software co-ordination. Use cpufreq affected_cpus
 211          * interface to handle this scenario. Additional is_smp() check
 212          * is to keep SMP_ON_UP build working.
 213          */
 214         if (is_smp()) {
 215                 policy->shared_type = CPUFREQ_SHARED_TYPE_ANY;
 216                 cpumask_setall(policy->cpus);
 217         }
 218
 219         /* FIXME: what's the actual transition time? */
 220         policy->cpuinfo.transition_latency = 300 * 1000;
 221
 222         return 0;
 223
 224 fail_table:
 225         freq_table_free();
 226 fail_ck:
 227         clk_put(mpu_clk);
 228         return result;
 229 }
 230
 231 static int omap_cpu_exit(struct cpufreq_policy *policy)
 232 {
 233         freq_table_free();
 234         clk_put(mpu_clk);
 235         return 0;
 236 }
 237
 238 static struct freq_attr *omap_cpufreq_attr[] = {
 239         &cpufreq_freq_attr_scaling_available_freqs,
 240         NULL,
 241 };
 242
 243 static struct cpufreq_driver omap_driver = {
 244         .flags          = CPUFREQ_STICKY,
 245         .verify         = omap_verify_speed,
 246         .target         = omap_target,
 247         .get            = omap_getspeed,
 248         .init           = omap_cpu_init,
 249         .exit           = omap_cpu_exit,
 250         .name           = "omap",
 251         .attr           = omap_cpufreq_attr,
 252 };
 253
 254 static int __init omap_cpufreq_init(void)
 255 {
 256         mpu_dev = get_cpu_device(0);
 257         if (!mpu_dev) {
 258                 pr_warning("%s: unable to get the mpu device\n", __func__);
 259                 return -EINVAL;
 260         }
 261
 262         mpu_reg = regulator_get(mpu_dev, "vcc");
 263         if (IS_ERR(mpu_reg)) {
 264                 pr_warning("%s: unable to get MPU regulator\n", __func__);
 265                 mpu_reg = NULL;
 266         } else {
 267                 /*
 268                  * Ensure physical regulator is present.
 269                  * (e.g. could be dummy regulator.)
 270                  */
 271                 if (regulator_get_voltage(mpu_reg) < 0) {
 272                         pr_warn("%s: physical regulator not present for MPU\n",
 273                                 __func__);
 274                         regulator_put(mpu_reg);
 275                         mpu_reg = NULL;
 276                 }
 277         }
 278
 279         return cpufreq_register_driver(&omap_driver);
 280 }
 281
 282 static void __exit omap_cpufreq_exit(void)
 283 {
 284         cpufreq_unregister_driver(&omap_driver);
 285 }
 286
 287 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
 288 MODULE_LICENSE("GPL");
 289 module_init(omap_cpufreq_init);
 290 module_exit(omap_cpufreq_exit);