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                 rcu_read_lock();
  67                 opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
  68                 if (IS_ERR(opp)) {
  69                         rcu_read_unlock();
  70                         dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
  71                                 __func__, new_freq);
  72                         return -EINVAL;
  73                 }
  74                 volt = dev_pm_opp_get_voltage(opp);
  75                 rcu_read_unlock();
  76                 tol = volt * OPP_TOLERANCE / 100;
  77                 volt_old = regulator_get_voltage(mpu_reg);
  78         }
  79
  80         dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
  81                 old_freq / 1000, volt_old ? volt_old / 1000 : -1,
  82                 new_freq / 1000, volt ? volt / 1000 : -1);
  83
  84         /* scaling up?  scale voltage before frequency */
  85         if (mpu_reg && (new_freq > old_freq)) {
  86                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
  87                 if (r < 0) {
  88                         dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
  89                                  __func__);
  90                         return r;
  91                 }
  92         }
  93
  94         ret = clk_set_rate(policy->clk, new_freq * 1000);
  95
  96         /* scaling down?  scale voltage after frequency */
  97         if (mpu_reg && (new_freq < old_freq)) {
  98                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
  99                 if (r < 0) {
 100                         dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
 101                                  __func__);
 102                         clk_set_rate(policy->clk, old_freq * 1000);
 103                         return r;
 104                 }
 105         }
 106
 107         return ret;
 108 }
 109
 110 static inline void freq_table_free(void)
 111 {
 112         if (atomic_dec_and_test(&freq_table_users))
 113                 dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
 114 }
 115
 116 static int omap_cpu_init(struct cpufreq_policy *policy)
 117 {
 118         int result;
 119
 120         policy->clk = clk_get(NULL, "cpufreq_ck");
 121         if (IS_ERR(policy->clk))
 122                 return PTR_ERR(policy->clk);
 123
 124         if (!freq_table) {
 125                 result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
 126                 if (result) {
 127                         dev_err(mpu_dev,
 128                                 "%s: cpu%d: failed creating freq table[%d]\n",
 129                                 __func__, policy->cpu, result);
 130                         goto fail;
 131                 }
 132         }
 133
 134         atomic_inc_return(&freq_table_users);
 135
 136         /* FIXME: what's the actual transition time? */
 137         result = cpufreq_generic_init(policy, freq_table, 300 * 1000);
 138         if (!result)
 139                 return 0;
 140
 141         freq_table_free();
 142 fail:
 143         clk_put(policy->clk);
 144         return result;
 145 }
 146
 147 static int omap_cpu_exit(struct cpufreq_policy *policy)
 148 {
 149         freq_table_free();
 150         clk_put(policy->clk);
 151         return 0;
 152 }
 153
 154 static struct cpufreq_driver omap_driver = {
 155         .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 156         .verify         = cpufreq_generic_frequency_table_verify,
 157         .target_index   = omap_target,
 158         .get            = cpufreq_generic_get,
 159         .init           = omap_cpu_init,
 160         .exit           = omap_cpu_exit,
 161         .name           = "omap",
 162         .attr           = cpufreq_generic_attr,
 163 };
 164
 165 static int omap_cpufreq_probe(struct platform_device *pdev)
 166 {
 167         mpu_dev = get_cpu_device(0);
 168         if (!mpu_dev) {
 169                 pr_warn("%s: unable to get the MPU device\n", __func__);
 170                 return -EINVAL;
 171         }
 172
 173         mpu_reg = regulator_get(mpu_dev, "vcc");
 174         if (IS_ERR(mpu_reg)) {
 175                 pr_warn("%s: unable to get MPU regulator\n", __func__);
 176                 mpu_reg = NULL;
 177         } else {
 178                 /*
 179                  * Ensure physical regulator is present.
 180                  * (e.g. could be dummy regulator.)
 181                  */
 182                 if (regulator_get_voltage(mpu_reg) < 0) {
 183                         pr_warn("%s: physical regulator not present for MPU\n",
 184                                 __func__);
 185                         regulator_put(mpu_reg);
 186                         mpu_reg = NULL;
 187                 }
 188         }
 189
 190         return cpufreq_register_driver(&omap_driver);
 191 }
 192
 193 static int omap_cpufreq_remove(struct platform_device *pdev)
 194 {
 195         return cpufreq_unregister_driver(&omap_driver);
 196 }
 197
 198 static struct platform_driver omap_cpufreq_platdrv = {
 199         .driver = {
 200                 .name   = "omap-cpufreq",
 201         },
 202         .probe          = omap_cpufreq_probe,
 203         .remove         = omap_cpufreq_remove,
 204 };
 205 module_platform_driver(omap_cpufreq_platdrv);
 206
 207 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
 208 MODULE_LICENSE("GPL");