linux/drivers/cpufreq/omap-cpufreq.c
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   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
  37static struct cpufreq_frequency_table *freq_table;
  38static atomic_t freq_table_users = ATOMIC_INIT(0);
  39static struct device *mpu_dev;
  40static struct regulator *mpu_reg;
  41
  42static 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
 105static 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
 111static 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(mpu_dev, policy->cpus);
 135
 136        return 0;
 137}
 138
 139static int omap_cpu_exit(struct cpufreq_policy *policy)
 140{
 141        freq_table_free();
 142        clk_put(policy->clk);
 143        return 0;
 144}
 145
 146static struct cpufreq_driver omap_driver = {
 147        .flags          = 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
 157static 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
 185static int omap_cpufreq_remove(struct platform_device *pdev)
 186{
 187        return cpufreq_unregister_driver(&omap_driver);
 188}
 189
 190static struct platform_driver omap_cpufreq_platdrv = {
 191        .driver = {
 192                .name   = "omap-cpufreq",
 193        },
 194        .probe          = omap_cpufreq_probe,
 195        .remove         = omap_cpufreq_remove,
 196};
 197module_platform_driver(omap_cpufreq_platdrv);
 198
 199MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
 200MODULE_LICENSE("GPL");
 201