linux/drivers/cpufreq/cpufreq-cpu0.c
<<
>>
Prefs
   1/*
   2 * Copyright (C) 2012 Freescale Semiconductor, Inc.
   3 *
   4 * The OPP code in function cpu0_set_target() is reused from
   5 * drivers/cpufreq/omap-cpufreq.c
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 */
  11
  12#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  13
  14#include <linux/clk.h>
  15#include <linux/cpu.h>
  16#include <linux/cpu_cooling.h>
  17#include <linux/cpufreq.h>
  18#include <linux/cpumask.h>
  19#include <linux/err.h>
  20#include <linux/module.h>
  21#include <linux/of.h>
  22#include <linux/pm_opp.h>
  23#include <linux/platform_device.h>
  24#include <linux/regulator/consumer.h>
  25#include <linux/slab.h>
  26#include <linux/thermal.h>
  27
  28static unsigned int transition_latency;
  29static unsigned int voltage_tolerance; /* in percentage */
  30
  31static struct device *cpu_dev;
  32static struct clk *cpu_clk;
  33static struct regulator *cpu_reg;
  34static struct cpufreq_frequency_table *freq_table;
  35static struct thermal_cooling_device *cdev;
  36
  37static int cpu0_set_target(struct cpufreq_policy *policy, unsigned int index)
  38{
  39        struct dev_pm_opp *opp;
  40        unsigned long volt = 0, volt_old = 0, tol = 0;
  41        unsigned int old_freq, new_freq;
  42        long freq_Hz, freq_exact;
  43        int ret;
  44
  45        freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
  46        if (freq_Hz <= 0)
  47                freq_Hz = freq_table[index].frequency * 1000;
  48
  49        freq_exact = freq_Hz;
  50        new_freq = freq_Hz / 1000;
  51        old_freq = clk_get_rate(cpu_clk) / 1000;
  52
  53        if (!IS_ERR(cpu_reg)) {
  54                rcu_read_lock();
  55                opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_Hz);
  56                if (IS_ERR(opp)) {
  57                        rcu_read_unlock();
  58                        pr_err("failed to find OPP for %ld\n", freq_Hz);
  59                        return PTR_ERR(opp);
  60                }
  61                volt = dev_pm_opp_get_voltage(opp);
  62                rcu_read_unlock();
  63                tol = volt * voltage_tolerance / 100;
  64                volt_old = regulator_get_voltage(cpu_reg);
  65        }
  66
  67        pr_debug("%u MHz, %ld mV --> %u MHz, %ld mV\n",
  68                 old_freq / 1000, volt_old ? volt_old / 1000 : -1,
  69                 new_freq / 1000, volt ? volt / 1000 : -1);
  70
  71        /* scaling up?  scale voltage before frequency */
  72        if (!IS_ERR(cpu_reg) && new_freq > old_freq) {
  73                ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
  74                if (ret) {
  75                        pr_err("failed to scale voltage up: %d\n", ret);
  76                        return ret;
  77                }
  78        }
  79
  80        ret = clk_set_rate(cpu_clk, freq_exact);
  81        if (ret) {
  82                pr_err("failed to set clock rate: %d\n", ret);
  83                if (!IS_ERR(cpu_reg))
  84                        regulator_set_voltage_tol(cpu_reg, volt_old, tol);
  85                return ret;
  86        }
  87
  88        /* scaling down?  scale voltage after frequency */
  89        if (!IS_ERR(cpu_reg) && new_freq < old_freq) {
  90                ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
  91                if (ret) {
  92                        pr_err("failed to scale voltage down: %d\n", ret);
  93                        clk_set_rate(cpu_clk, old_freq * 1000);
  94                }
  95        }
  96
  97        return ret;
  98}
  99
 100static int cpu0_cpufreq_init(struct cpufreq_policy *policy)
 101{
 102        policy->clk = cpu_clk;
 103        return cpufreq_generic_init(policy, freq_table, transition_latency);
 104}
 105
 106static struct cpufreq_driver cpu0_cpufreq_driver = {
 107        .flags = CPUFREQ_STICKY,
 108        .verify = cpufreq_generic_frequency_table_verify,
 109        .target_index = cpu0_set_target,
 110        .get = cpufreq_generic_get,
 111        .init = cpu0_cpufreq_init,
 112        .exit = cpufreq_generic_exit,
 113        .name = "generic_cpu0",
 114        .attr = cpufreq_generic_attr,
 115};
 116
 117static int cpu0_cpufreq_probe(struct platform_device *pdev)
 118{
 119        struct device_node *np;
 120        int ret;
 121
 122        cpu_dev = get_cpu_device(0);
 123        if (!cpu_dev) {
 124                pr_err("failed to get cpu0 device\n");
 125                return -ENODEV;
 126        }
 127
 128        np = of_node_get(cpu_dev->of_node);
 129        if (!np) {
 130                pr_err("failed to find cpu0 node\n");
 131                return -ENOENT;
 132        }
 133
 134        cpu_reg = devm_regulator_get_optional(cpu_dev, "cpu0");
 135        if (IS_ERR(cpu_reg)) {
 136                /*
 137                 * If cpu0 regulator supply node is present, but regulator is
 138                 * not yet registered, we should try defering probe.
 139                 */
 140                if (PTR_ERR(cpu_reg) == -EPROBE_DEFER) {
 141                        dev_err(cpu_dev, "cpu0 regulator not ready, retry\n");
 142                        ret = -EPROBE_DEFER;
 143                        goto out_put_node;
 144                }
 145                pr_warn("failed to get cpu0 regulator: %ld\n",
 146                        PTR_ERR(cpu_reg));
 147        }
 148
 149        cpu_clk = devm_clk_get(cpu_dev, NULL);
 150        if (IS_ERR(cpu_clk)) {
 151                ret = PTR_ERR(cpu_clk);
 152                pr_err("failed to get cpu0 clock: %d\n", ret);
 153                goto out_put_node;
 154        }
 155
 156        ret = of_init_opp_table(cpu_dev);
 157        if (ret) {
 158                pr_err("failed to init OPP table: %d\n", ret);
 159                goto out_put_node;
 160        }
 161
 162        ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
 163        if (ret) {
 164                pr_err("failed to init cpufreq table: %d\n", ret);
 165                goto out_put_node;
 166        }
 167
 168        of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
 169
 170        if (of_property_read_u32(np, "clock-latency", &transition_latency))
 171                transition_latency = CPUFREQ_ETERNAL;
 172
 173        if (!IS_ERR(cpu_reg)) {
 174                struct dev_pm_opp *opp;
 175                unsigned long min_uV, max_uV;
 176                int i;
 177
 178                /*
 179                 * OPP is maintained in order of increasing frequency, and
 180                 * freq_table initialised from OPP is therefore sorted in the
 181                 * same order.
 182                 */
 183                for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
 184                        ;
 185                rcu_read_lock();
 186                opp = dev_pm_opp_find_freq_exact(cpu_dev,
 187                                freq_table[0].frequency * 1000, true);
 188                min_uV = dev_pm_opp_get_voltage(opp);
 189                opp = dev_pm_opp_find_freq_exact(cpu_dev,
 190                                freq_table[i-1].frequency * 1000, true);
 191                max_uV = dev_pm_opp_get_voltage(opp);
 192                rcu_read_unlock();
 193                ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
 194                if (ret > 0)
 195                        transition_latency += ret * 1000;
 196        }
 197
 198        ret = cpufreq_register_driver(&cpu0_cpufreq_driver);
 199        if (ret) {
 200                pr_err("failed register driver: %d\n", ret);
 201                goto out_free_table;
 202        }
 203
 204        /*
 205         * For now, just loading the cooling device;
 206         * thermal DT code takes care of matching them.
 207         */
 208        if (of_find_property(np, "#cooling-cells", NULL)) {
 209                cdev = of_cpufreq_cooling_register(np, cpu_present_mask);
 210                if (IS_ERR(cdev))
 211                        pr_err("running cpufreq without cooling device: %ld\n",
 212                               PTR_ERR(cdev));
 213        }
 214
 215        of_node_put(np);
 216        return 0;
 217
 218out_free_table:
 219        dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
 220out_put_node:
 221        of_node_put(np);
 222        return ret;
 223}
 224
 225static int cpu0_cpufreq_remove(struct platform_device *pdev)
 226{
 227        cpufreq_cooling_unregister(cdev);
 228        cpufreq_unregister_driver(&cpu0_cpufreq_driver);
 229        dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
 230
 231        return 0;
 232}
 233
 234static struct platform_driver cpu0_cpufreq_platdrv = {
 235        .driver = {
 236                .name   = "cpufreq-cpu0",
 237                .owner  = THIS_MODULE,
 238        },
 239        .probe          = cpu0_cpufreq_probe,
 240        .remove         = cpu0_cpufreq_remove,
 241};
 242module_platform_driver(cpu0_cpufreq_platdrv);
 243
 244MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
 245MODULE_DESCRIPTION("Generic CPU0 cpufreq driver");
 246MODULE_LICENSE("GPL");
 247
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.