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 clk *mpu_clk;
  40 static struct device *mpu_dev;
  41 static struct regulator *mpu_reg;
  42
  43 static unsigned int omap_getspeed(unsigned int cpu)
  44 {
  45         unsigned long rate;
  46
  47         if (cpu >= NR_CPUS)
  48                 return 0;
  49
  50         rate = clk_get_rate(mpu_clk) / 1000;
  51         return rate;
  52 }
  53
  54 static int omap_target(struct cpufreq_policy *policy, unsigned int index)
  55 {
  56         int r, ret;
  57         struct dev_pm_opp *opp;
  58         unsigned long freq, volt = 0, volt_old = 0, tol = 0;
  59         unsigned int old_freq, new_freq;
  60
  61         old_freq = omap_getspeed(policy->cpu);
  62         new_freq = freq_table[index].frequency;
  63
  64         freq = new_freq * 1000;
  65         ret = clk_round_rate(mpu_clk, freq);
  66         if (IS_ERR_VALUE(ret)) {
  67                 dev_warn(mpu_dev,
  68                          "CPUfreq: Cannot find matching frequency for %lu\n",
  69                          freq);
  70                 return ret;
  71         }
  72         freq = ret;
  73
  74         if (mpu_reg) {
  75                 rcu_read_lock();
  76                 opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
  77                 if (IS_ERR(opp)) {
  78                         rcu_read_unlock();
  79                         dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
  80                                 __func__, new_freq);
  81                         return -EINVAL;
  82                 }
  83                 volt = dev_pm_opp_get_voltage(opp);
  84                 rcu_read_unlock();
  85                 tol = volt * OPP_TOLERANCE / 100;
  86                 volt_old = regulator_get_voltage(mpu_reg);
  87         }
  88
  89         dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
  90                 old_freq / 1000, volt_old ? volt_old / 1000 : -1,
  91                 new_freq / 1000, volt ? volt / 1000 : -1);
  92
  93         /* scaling up?  scale voltage before 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 up.\n",
  98                                  __func__);
  99                         return r;
 100                 }
 101         }
 102
 103         ret = clk_set_rate(mpu_clk, new_freq * 1000);
 104
 105         /* scaling down?  scale voltage after frequency */
 106         if (mpu_reg && (new_freq < old_freq)) {
 107                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
 108                 if (r < 0) {
 109                         dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
 110                                  __func__);
 111                         clk_set_rate(mpu_clk, old_freq * 1000);
 112                         return r;
 113                 }
 114         }
 115
 116         return ret;
 117 }
 118
 119 static inline void freq_table_free(void)
 120 {
 121         if (atomic_dec_and_test(&freq_table_users))
 122                 dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
 123 }
 124
 125 static int omap_cpu_init(struct cpufreq_policy *policy)
 126 {
 127         int result;
 128
 129         mpu_clk = clk_get(NULL, "cpufreq_ck");
 130         if (IS_ERR(mpu_clk))
 131                 return PTR_ERR(mpu_clk);
 132
 133         if (!freq_table) {
 134                 result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
 135                 if (result) {
 136                         dev_err(mpu_dev,
 137                                 "%s: cpu%d: failed creating freq table[%d]\n",
 138                                 __func__, policy->cpu, result);
 139                         goto fail;
 140                 }
 141         }
 142
 143         atomic_inc_return(&freq_table_users);
 144
 145         /* FIXME: what's the actual transition time? */
 146         result = cpufreq_generic_init(policy, freq_table, 300 * 1000);
 147         if (!result)
 148                 return 0;
 149
 150         freq_table_free();
 151 fail:
 152         clk_put(mpu_clk);
 153         return result;
 154 }
 155
 156 static int omap_cpu_exit(struct cpufreq_policy *policy)
 157 {
 158         cpufreq_frequency_table_put_attr(policy->cpu);
 159         freq_table_free();
 160         clk_put(mpu_clk);
 161         return 0;
 162 }
 163
 164 static struct cpufreq_driver omap_driver = {
 165         .flags          = CPUFREQ_STICKY,
 166         .verify         = cpufreq_generic_frequency_table_verify,
 167         .target_index   = omap_target,
 168         .get            = omap_getspeed,
 169         .init           = omap_cpu_init,
 170         .exit           = omap_cpu_exit,
 171         .name           = "omap",
 172         .attr           = cpufreq_generic_attr,
 173 };
 174
 175 static int omap_cpufreq_probe(struct platform_device *pdev)
 176 {
 177         mpu_dev = get_cpu_device(0);
 178         if (!mpu_dev) {
 179                 pr_warning("%s: unable to get the mpu device\n", __func__);
 180                 return -EINVAL;
 181         }
 182
 183         mpu_reg = regulator_get(mpu_dev, "vcc");
 184         if (IS_ERR(mpu_reg)) {
 185                 pr_warning("%s: unable to get MPU regulator\n", __func__);
 186                 mpu_reg = NULL;
 187         } else {
 188                 /*
 189                  * Ensure physical regulator is present.
 190                  * (e.g. could be dummy regulator.)
 191                  */
 192                 if (regulator_get_voltage(mpu_reg) < 0) {
 193                         pr_warn("%s: physical regulator not present for MPU\n",
 194                                 __func__);
 195                         regulator_put(mpu_reg);
 196                         mpu_reg = NULL;
 197                 }
 198         }
 199
 200         return cpufreq_register_driver(&omap_driver);
 201 }
 202
 203 static int omap_cpufreq_remove(struct platform_device *pdev)
 204 {
 205         return cpufreq_unregister_driver(&omap_driver);
 206 }
 207
 208 static struct platform_driver omap_cpufreq_platdrv = {
 209         .driver = {
 210                 .name   = "omap-cpufreq",
 211                 .owner  = THIS_MODULE,
 212         },
 213         .probe          = omap_cpufreq_probe,
 214         .remove         = omap_cpufreq_remove,
 215 };
 216 module_platform_driver(omap_cpufreq_platdrv);
 217
 218 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
 219 MODULE_LICENSE("GPL");