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
  17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19 #include <linux/types.h>
  20 #include <linux/kernel.h>
  21 #include <linux/sched.h>
  22 #include <linux/cpufreq.h>
  23 #include <linux/delay.h>
  24 #include <linux/init.h>
  25 #include <linux/err.h>
  26 #include <linux/clk.h>
  27 #include <linux/io.h>
  28 #include <linux/pm_opp.h>
  29 #include <linux/cpu.h>
  30 #include <linux/module.h>
  31 #include <linux/platform_device.h>
  32 #include <linux/regulator/consumer.h>
  33
  34 #include <asm/smp_plat.h>
  35 #include <asm/cpu.h>
  36
  37 /* OPP tolerance in percentage */
  38 #define OPP_TOLERANCE   4
  39
  40 static struct cpufreq_frequency_table *freq_table;
  41 static atomic_t freq_table_users = ATOMIC_INIT(0);
  42 static struct device *mpu_dev;
  43 static struct regulator *mpu_reg;
  44
  45 static int omap_target(struct cpufreq_policy *policy, unsigned int index)
  46 {
  47         int r, ret;
  48         struct dev_pm_opp *opp;
  49         unsigned long freq, volt = 0, volt_old = 0, tol = 0;
  50         unsigned int old_freq, new_freq;
  51
  52         old_freq = policy->cur;
  53         new_freq = freq_table[index].frequency;
  54
  55         freq = new_freq * 1000;
  56         ret = clk_round_rate(policy->clk, freq);
  57         if (ret < 0) {
  58                 dev_warn(mpu_dev,
  59                          "CPUfreq: Cannot find matching frequency for %lu\n",
  60                          freq);
  61                 return ret;
  62         }
  63         freq = ret;
  64
  65         if (mpu_reg) {
  66                 opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
  67                 if (IS_ERR(opp)) {
  68                         dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
  69                                 __func__, new_freq);
  70                         return -EINVAL;
  71                 }
  72                 volt = dev_pm_opp_get_voltage(opp);
  73                 dev_pm_opp_put(opp);
  74                 tol = volt * OPP_TOLERANCE / 100;
  75                 volt_old = regulator_get_voltage(mpu_reg);
  76         }
  77
  78         dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
  79                 old_freq / 1000, volt_old ? volt_old / 1000 : -1,
  80                 new_freq / 1000, volt ? volt / 1000 : -1);
  81
  82         /* scaling up?  scale voltage before frequency */
  83         if (mpu_reg && (new_freq > old_freq)) {
  84                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
  85                 if (r < 0) {
  86                         dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
  87                                  __func__);
  88                         return r;
  89                 }
  90         }
  91
  92         ret = clk_set_rate(policy->clk, new_freq * 1000);
  93
  94         /* scaling down?  scale voltage after frequency */
  95         if (mpu_reg && (new_freq < old_freq)) {
  96                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
  97                 if (r < 0) {
  98                         dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
  99                                  __func__);
 100                         clk_set_rate(policy->clk, old_freq * 1000);
 101                         return r;
 102                 }
 103         }
 104
 105         return ret;
 106 }
 107
 108 static inline void freq_table_free(void)
 109 {
 110         if (atomic_dec_and_test(&freq_table_users))
 111                 dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
 112 }
 113
 114 static int omap_cpu_init(struct cpufreq_policy *policy)
 115 {
 116         int result;
 117
 118         policy->clk = clk_get(NULL, "cpufreq_ck");
 119         if (IS_ERR(policy->clk))
 120                 return PTR_ERR(policy->clk);
 121
 122         if (!freq_table) {
 123                 result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
 124                 if (result) {
 125                         dev_err(mpu_dev,
 126                                 "%s: cpu%d: failed creating freq table[%d]\n",
 127                                 __func__, policy->cpu, result);
 128                         goto fail;
 129                 }
 130         }
 131
 132         atomic_inc_return(&freq_table_users);
 133
 134         /* FIXME: what's the actual transition time? */
 135         result = cpufreq_generic_init(policy, freq_table, 300 * 1000);
 136         if (!result)
 137                 return 0;
 138
 139         freq_table_free();
 140 fail:
 141         clk_put(policy->clk);
 142         return result;
 143 }
 144
 145 static int omap_cpu_exit(struct cpufreq_policy *policy)
 146 {
 147         freq_table_free();
 148         clk_put(policy->clk);
 149         return 0;
 150 }
 151
 152 static struct cpufreq_driver omap_driver = {
 153         .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 154         .verify         = cpufreq_generic_frequency_table_verify,
 155         .target_index   = omap_target,
 156         .get            = cpufreq_generic_get,
 157         .init           = omap_cpu_init,
 158         .exit           = omap_cpu_exit,
 159         .name           = "omap",
 160         .attr           = cpufreq_generic_attr,
 161 };
 162
 163 static int omap_cpufreq_probe(struct platform_device *pdev)
 164 {
 165         mpu_dev = get_cpu_device(0);
 166         if (!mpu_dev) {
 167                 pr_warn("%s: unable to get the MPU device\n", __func__);
 168                 return -EINVAL;
 169         }
 170
 171         mpu_reg = regulator_get(mpu_dev, "vcc");
 172         if (IS_ERR(mpu_reg)) {
 173                 pr_warn("%s: unable to get MPU regulator\n", __func__);
 174                 mpu_reg = NULL;
 175         } else {
 176                 /*
 177                  * Ensure physical regulator is present.
 178                  * (e.g. could be dummy regulator.)
 179                  */
 180                 if (regulator_get_voltage(mpu_reg) < 0) {
 181                         pr_warn("%s: physical regulator not present for MPU\n",
 182                                 __func__);
 183                         regulator_put(mpu_reg);
 184                         mpu_reg = NULL;
 185                 }
 186         }
 187
 188         return cpufreq_register_driver(&omap_driver);
 189 }
 190
 191 static int omap_cpufreq_remove(struct platform_device *pdev)
 192 {
 193         return cpufreq_unregister_driver(&omap_driver);
 194 }
 195
 196 static struct platform_driver omap_cpufreq_platdrv = {
 197         .driver = {
 198                 .name   = "omap-cpufreq",
 199         },
 200         .probe          = omap_cpufreq_probe,
 201         .remove         = omap_cpufreq_remove,
 202 };
 203 module_platform_driver(omap_cpufreq_platdrv);
 204
 205 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
 206 MODULE_LICENSE("GPL");