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/pm_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 device *mpu_dev;
  40 static struct regulator *mpu_reg;
  41
  42 static int omap_target(struct cpufreq_policy *policy, unsigned int index)
  43 {
  44         int r, ret;
  45         struct dev_pm_opp *opp;
  46         unsigned long freq, volt = 0, volt_old = 0, tol = 0;
  47         unsigned int old_freq, new_freq;
  48
  49         old_freq = policy->cur;
  50         new_freq = freq_table[index].frequency;
  51
  52         freq = new_freq * 1000;
  53         ret = clk_round_rate(policy->clk, freq);
  54         if (IS_ERR_VALUE(ret)) {
  55                 dev_warn(mpu_dev,
  56                          "CPUfreq: Cannot find matching frequency for %lu\n",
  57                          freq);
  58                 return ret;
  59         }
  60         freq = ret;
  61
  62         if (mpu_reg) {
  63                 rcu_read_lock();
  64                 opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
  65                 if (IS_ERR(opp)) {
  66                         rcu_read_unlock();
  67                         dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
  68                                 __func__, new_freq);
  69                         return -EINVAL;
  70                 }
  71                 volt = dev_pm_opp_get_voltage(opp);
  72                 rcu_read_unlock();
  73                 tol = volt * OPP_TOLERANCE / 100;
  74                 volt_old = regulator_get_voltage(mpu_reg);
  75         }
  76
  77         dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
  78                 old_freq / 1000, volt_old ? volt_old / 1000 : -1,
  79                 new_freq / 1000, volt ? volt / 1000 : -1);
  80
  81         /* scaling up?  scale voltage before frequency */
  82         if (mpu_reg && (new_freq > old_freq)) {
  83                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
  84                 if (r < 0) {
  85                         dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
  86                                  __func__);
  87                         return r;
  88                 }
  89         }
  90
  91         ret = clk_set_rate(policy->clk, new_freq * 1000);
  92
  93         /* scaling down?  scale voltage after frequency */
  94         if (mpu_reg && (new_freq < old_freq)) {
  95                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
  96                 if (r < 0) {
  97                         dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
  98                                  __func__);
  99                         clk_set_rate(policy->clk, old_freq * 1000);
 100                         return r;
 101                 }
 102         }
 103
 104         return ret;
 105 }
 106
 107 static inline void freq_table_free(void)
 108 {
 109         if (atomic_dec_and_test(&freq_table_users))
 110                 dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
 111 }
 112
 113 static int omap_cpu_init(struct cpufreq_policy *policy)
 114 {
 115         int result;
 116
 117         policy->clk = clk_get(NULL, "cpufreq_ck");
 118         if (IS_ERR(policy->clk))
 119                 return PTR_ERR(policy->clk);
 120
 121         if (!freq_table) {
 122                 result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
 123                 if (result) {
 124                         dev_err(mpu_dev,
 125                                 "%s: cpu%d: failed creating freq table[%d]\n",
 126                                 __func__, policy->cpu, result);
 127                         goto fail;
 128                 }
 129         }
 130
 131         atomic_inc_return(&freq_table_users);
 132
 133         /* FIXME: what's the actual transition time? */
 134         result = cpufreq_generic_init(policy, freq_table, 300 * 1000);
 135         if (!result)
 136                 return 0;
 137
 138         freq_table_free();
 139 fail:
 140         clk_put(policy->clk);
 141         return result;
 142 }
 143
 144 static int omap_cpu_exit(struct cpufreq_policy *policy)
 145 {
 146         freq_table_free();
 147         clk_put(policy->clk);
 148         return 0;
 149 }
 150
 151 static struct cpufreq_driver omap_driver = {
 152         .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 153         .verify         = cpufreq_generic_frequency_table_verify,
 154         .target_index   = omap_target,
 155         .get            = cpufreq_generic_get,
 156         .init           = omap_cpu_init,
 157         .exit           = omap_cpu_exit,
 158         .name           = "omap",
 159         .attr           = cpufreq_generic_attr,
 160 };
 161
 162 static int omap_cpufreq_probe(struct platform_device *pdev)
 163 {
 164         mpu_dev = get_cpu_device(0);
 165         if (!mpu_dev) {
 166                 pr_warning("%s: unable to get the mpu device\n", __func__);
 167                 return -EINVAL;
 168         }
 169
 170         mpu_reg = regulator_get(mpu_dev, "vcc");
 171         if (IS_ERR(mpu_reg)) {
 172                 pr_warning("%s: unable to get MPU regulator\n", __func__);
 173                 mpu_reg = NULL;
 174         } else {
 175                 /*
 176                  * Ensure physical regulator is present.
 177                  * (e.g. could be dummy regulator.)
 178                  */
 179                 if (regulator_get_voltage(mpu_reg) < 0) {
 180                         pr_warn("%s: physical regulator not present for MPU\n",
 181                                 __func__);
 182                         regulator_put(mpu_reg);
 183                         mpu_reg = NULL;
 184                 }
 185         }
 186
 187         return cpufreq_register_driver(&omap_driver);
 188 }
 189
 190 static int omap_cpufreq_remove(struct platform_device *pdev)
 191 {
 192         return cpufreq_unregister_driver(&omap_driver);
 193 }
 194
 195 static struct platform_driver omap_cpufreq_platdrv = {
 196         .driver = {
 197                 .name   = "omap-cpufreq",
 198         },
 199         .probe          = omap_cpufreq_probe,
 200         .remove         = omap_cpufreq_remove,
 201 };
 202 module_platform_driver(omap_cpufreq_platdrv);
 203
 204 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
 205 MODULE_LICENSE("GPL");