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/platform_device.h>
  29 #include <linux/regulator/consumer.h>
  30
  31 #include <asm/smp_plat.h>
  32 #include <asm/cpu.h>
  33
  34 /* OPP tolerance in percentage */
  35 #define OPP_TOLERANCE   4
  36
  37 static struct cpufreq_frequency_table *freq_table;
  38 static atomic_t freq_table_users = ATOMIC_INIT(0);
  39 static struct clk *mpu_clk;
  40 static struct device *mpu_dev;
  41 static struct regulator *mpu_reg;
  42
  43 static int omap_verify_speed(struct cpufreq_policy *policy)
  44 {
  45         if (!freq_table)
  46                 return -EINVAL;
  47         return cpufreq_frequency_table_verify(policy, freq_table);
  48 }
  49
  50 static unsigned int omap_getspeed(unsigned int cpu)
  51 {
  52         unsigned long rate;
  53
  54         if (cpu >= NR_CPUS)
  55                 return 0;
  56
  57         rate = clk_get_rate(mpu_clk) / 1000;
  58         return rate;
  59 }
  60
  61 static int omap_target(struct cpufreq_policy *policy,
  62                        unsigned int target_freq,
  63                        unsigned int relation)
  64 {
  65         unsigned int i;
  66         int r, ret = 0;
  67         struct cpufreq_freqs freqs;
  68         struct opp *opp;
  69         unsigned long freq, volt = 0, volt_old = 0, tol = 0;
  70
  71         if (!freq_table) {
  72                 dev_err(mpu_dev, "%s: cpu%d: no freq table!\n", __func__,
  73                                 policy->cpu);
  74                 return -EINVAL;
  75         }
  76
  77         ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
  78                         relation, &i);
  79         if (ret) {
  80                 dev_dbg(mpu_dev, "%s: cpu%d: no freq match for %d(ret=%d)\n",
  81                         __func__, policy->cpu, target_freq, ret);
  82                 return ret;
  83         }
  84         freqs.new = freq_table[i].frequency;
  85         if (!freqs.new) {
  86                 dev_err(mpu_dev, "%s: cpu%d: no match for freq %d\n", __func__,
  87                         policy->cpu, target_freq);
  88                 return -EINVAL;
  89         }
  90
  91         freqs.old = omap_getspeed(policy->cpu);
  92
  93         if (freqs.old == freqs.new && policy->cur == freqs.new)
  94                 return ret;
  95
  96         /* notifiers */
  97         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  98
  99         freq = freqs.new * 1000;
 100         ret = clk_round_rate(mpu_clk, freq);
 101         if (IS_ERR_VALUE(ret)) {
 102                 dev_warn(mpu_dev,
 103                          "CPUfreq: Cannot find matching frequency for %lu\n",
 104                          freq);
 105                 return ret;
 106         }
 107         freq = ret;
 108
 109         if (mpu_reg) {
 110                 rcu_read_lock();
 111                 opp = opp_find_freq_ceil(mpu_dev, &freq);
 112                 if (IS_ERR(opp)) {
 113                         rcu_read_unlock();
 114                         dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
 115                                 __func__, freqs.new);
 116                         return -EINVAL;
 117                 }
 118                 volt = opp_get_voltage(opp);
 119                 rcu_read_unlock();
 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         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 158
 159         return ret;
 160 }
 161
 162 static inline void freq_table_free(void)
 163 {
 164         if (atomic_dec_and_test(&freq_table_users))
 165                 opp_free_cpufreq_table(mpu_dev, &freq_table);
 166 }
 167
 168 static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy)
 169 {
 170         int result = 0;
 171
 172         mpu_clk = clk_get(NULL, "cpufreq_ck");
 173         if (IS_ERR(mpu_clk))
 174                 return PTR_ERR(mpu_clk);
 175
 176         if (policy->cpu >= NR_CPUS) {
 177                 result = -EINVAL;
 178                 goto fail_ck;
 179         }
 180
 181         policy->cur = omap_getspeed(policy->cpu);
 182
 183         if (!freq_table)
 184                 result = opp_init_cpufreq_table(mpu_dev, &freq_table);
 185
 186         if (result) {
 187                 dev_err(mpu_dev, "%s: cpu%d: failed creating freq table[%d]\n",
 188                                 __func__, policy->cpu, result);
 189                 goto fail_ck;
 190         }
 191
 192         atomic_inc_return(&freq_table_users);
 193
 194         result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 195         if (result)
 196                 goto fail_table;
 197
 198         cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 199
 200         policy->cur = omap_getspeed(policy->cpu);
 201
 202         /*
 203          * On OMAP SMP configuartion, both processors share the voltage
 204          * and clock. So both CPUs needs to be scaled together and hence
 205          * needs software co-ordination. Use cpufreq affected_cpus
 206          * interface to handle this scenario. Additional is_smp() check
 207          * is to keep SMP_ON_UP build working.
 208          */
 209         if (is_smp())
 210                 cpumask_setall(policy->cpus);
 211
 212         /* FIXME: what's the actual transition time? */
 213         policy->cpuinfo.transition_latency = 300 * 1000;
 214
 215         return 0;
 216
 217 fail_table:
 218         freq_table_free();
 219 fail_ck:
 220         clk_put(mpu_clk);
 221         return result;
 222 }
 223
 224 static int omap_cpu_exit(struct cpufreq_policy *policy)
 225 {
 226         freq_table_free();
 227         clk_put(mpu_clk);
 228         return 0;
 229 }
 230
 231 static struct freq_attr *omap_cpufreq_attr[] = {
 232         &cpufreq_freq_attr_scaling_available_freqs,
 233         NULL,
 234 };
 235
 236 static struct cpufreq_driver omap_driver = {
 237         .flags          = CPUFREQ_STICKY,
 238         .verify         = omap_verify_speed,
 239         .target         = omap_target,
 240         .get            = omap_getspeed,
 241         .init           = omap_cpu_init,
 242         .exit           = omap_cpu_exit,
 243         .name           = "omap",
 244         .attr           = omap_cpufreq_attr,
 245 };
 246
 247 static int omap_cpufreq_probe(struct platform_device *pdev)
 248 {
 249         mpu_dev = get_cpu_device(0);
 250         if (!mpu_dev) {
 251                 pr_warning("%s: unable to get the mpu device\n", __func__);
 252                 return -EINVAL;
 253         }
 254
 255         mpu_reg = regulator_get(mpu_dev, "vcc");
 256         if (IS_ERR(mpu_reg)) {
 257                 pr_warning("%s: unable to get MPU regulator\n", __func__);
 258                 mpu_reg = NULL;
 259         } else {
 260                 /*
 261                  * Ensure physical regulator is present.
 262                  * (e.g. could be dummy regulator.)
 263                  */
 264                 if (regulator_get_voltage(mpu_reg) < 0) {
 265                         pr_warn("%s: physical regulator not present for MPU\n",
 266                                 __func__);
 267                         regulator_put(mpu_reg);
 268                         mpu_reg = NULL;
 269                 }
 270         }
 271
 272         return cpufreq_register_driver(&omap_driver);
 273 }
 274
 275 static int omap_cpufreq_remove(struct platform_device *pdev)
 276 {
 277         return cpufreq_unregister_driver(&omap_driver);
 278 }
 279
 280 static struct platform_driver omap_cpufreq_platdrv = {
 281         .driver = {
 282                 .name   = "omap-cpufreq",
 283                 .owner  = THIS_MODULE,
 284         },
 285         .probe          = omap_cpufreq_probe,
 286         .remove         = omap_cpufreq_remove,
 287 };
 288 module_platform_driver(omap_cpufreq_platdrv);
 289
 290 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
 291 MODULE_LICENSE("GPL");