drivers/cpufreq/omap-cpufreq.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  CPU frequency scaling for OMAP using OPP information
   4  *
   5  *  Copyright (C) 2005 Nokia Corporation
   6  *  Written by Tony Lindgren <tony@atomide.com>
   7  *
   8  *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
   9  *
  10  * Copyright (C) 2007-2011 Texas Instruments, Inc.
  11  * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar
  12  */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  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 (ret < 0) {
  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                 opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
  64                 if (IS_ERR(opp)) {
  65                         dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
  66                                 __func__, new_freq);
  67                         return -EINVAL;
  68                 }
  69                 volt = dev_pm_opp_get_voltage(opp);
  70                 dev_pm_opp_put(opp);
  71                 tol = volt * OPP_TOLERANCE / 100;
  72                 volt_old = regulator_get_voltage(mpu_reg);
  73         }
  74
  75         dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
  76                 old_freq / 1000, volt_old ? volt_old / 1000 : -1,
  77                 new_freq / 1000, volt ? volt / 1000 : -1);
  78
  79         /* scaling up?  scale voltage before frequency */
  80         if (mpu_reg && (new_freq > old_freq)) {
  81                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
  82                 if (r < 0) {
  83                         dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
  84                                  __func__);
  85                         return r;
  86                 }
  87         }
  88
  89         ret = clk_set_rate(policy->clk, new_freq * 1000);
  90
  91         /* scaling down?  scale voltage after frequency */
  92         if (mpu_reg && (new_freq < old_freq)) {
  93                 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
  94                 if (r < 0) {
  95                         dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
  96                                  __func__);
  97                         clk_set_rate(policy->clk, old_freq * 1000);
  98                         return r;
  99                 }
 100         }
 101
 102         return ret;
 103 }
 104
 105 static inline void freq_table_free(void)
 106 {
 107         if (atomic_dec_and_test(&freq_table_users))
 108                 dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
 109 }
 110
 111 static int omap_cpu_init(struct cpufreq_policy *policy)
 112 {
 113         int result;
 114
 115         policy->clk = clk_get(NULL, "cpufreq_ck");
 116         if (IS_ERR(policy->clk))
 117                 return PTR_ERR(policy->clk);
 118
 119         if (!freq_table) {
 120                 result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
 121                 if (result) {
 122                         dev_err(mpu_dev,
 123                                 "%s: cpu%d: failed creating freq table[%d]\n",
 124                                 __func__, policy->cpu, result);
 125                         clk_put(policy->clk);
 126                         return result;
 127                 }
 128         }
 129
 130         atomic_inc_return(&freq_table_users);
 131
 132         /* FIXME: what's the actual transition time? */
 133         cpufreq_generic_init(policy, freq_table, 300 * 1000);
 134         dev_pm_opp_of_register_em(policy->cpus);
 135
 136         return 0;
 137 }
 138
 139 static int omap_cpu_exit(struct cpufreq_policy *policy)
 140 {
 141         freq_table_free();
 142         clk_put(policy->clk);
 143         return 0;
 144 }
 145
 146 static struct cpufreq_driver omap_driver = {
 147         .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 148         .verify         = cpufreq_generic_frequency_table_verify,
 149         .target_index   = omap_target,
 150         .get            = cpufreq_generic_get,
 151         .init           = omap_cpu_init,
 152         .exit           = omap_cpu_exit,
 153         .name           = "omap",
 154         .attr           = cpufreq_generic_attr,
 155 };
 156
 157 static int omap_cpufreq_probe(struct platform_device *pdev)
 158 {
 159         mpu_dev = get_cpu_device(0);
 160         if (!mpu_dev) {
 161                 pr_warn("%s: unable to get the MPU device\n", __func__);
 162                 return -EINVAL;
 163         }
 164
 165         mpu_reg = regulator_get(mpu_dev, "vcc");
 166         if (IS_ERR(mpu_reg)) {
 167                 pr_warn("%s: unable to get MPU regulator\n", __func__);
 168                 mpu_reg = NULL;
 169         } else {
 170                 /*
 171                  * Ensure physical regulator is present.
 172                  * (e.g. could be dummy regulator.)
 173                  */
 174                 if (regulator_get_voltage(mpu_reg) < 0) {
 175                         pr_warn("%s: physical regulator not present for MPU\n",
 176                                 __func__);
 177                         regulator_put(mpu_reg);
 178                         mpu_reg = NULL;
 179                 }
 180         }
 181
 182         return cpufreq_register_driver(&omap_driver);
 183 }
 184
 185 static int omap_cpufreq_remove(struct platform_device *pdev)
 186 {
 187         return cpufreq_unregister_driver(&omap_driver);
 188 }
 189
 190 static struct platform_driver omap_cpufreq_platdrv = {
 191         .driver = {
 192                 .name   = "omap-cpufreq",
 193         },
 194         .probe          = omap_cpufreq_probe,
 195         .remove         = omap_cpufreq_remove,
 196 };
 197 module_platform_driver(omap_cpufreq_platdrv);
 198
 199 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
 200 MODULE_LICENSE("GPL");