drivers/cpufreq/cpufreq-cpu0.c

   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/cpufreq.h>
  17 #include <linux/err.h>
  18 #include <linux/module.h>
  19 #include <linux/of.h>
  20 #include <linux/pm_opp.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/regulator/consumer.h>
  23 #include <linux/slab.h>
  24
  25 static unsigned int transition_latency;
  26 static unsigned int voltage_tolerance; /* in percentage */
  27
  28 static struct device *cpu_dev;
  29 static struct clk *cpu_clk;
  30 static struct regulator *cpu_reg;
  31 static struct cpufreq_frequency_table *freq_table;
  32
  33 static int cpu0_set_target(struct cpufreq_policy *policy, unsigned int index)
  34 {
  35         struct dev_pm_opp *opp;
  36         unsigned long volt = 0, volt_old = 0, tol = 0;
  37         unsigned int old_freq, new_freq;
  38         long freq_Hz, freq_exact;
  39         int ret;
  40
  41         freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
  42         if (freq_Hz <= 0)
  43                 freq_Hz = freq_table[index].frequency * 1000;
  44
  45         freq_exact = freq_Hz;
  46         new_freq = freq_Hz / 1000;
  47         old_freq = clk_get_rate(cpu_clk) / 1000;
  48
  49         if (!IS_ERR(cpu_reg)) {
  50                 rcu_read_lock();
  51                 opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_Hz);
  52                 if (IS_ERR(opp)) {
  53                         rcu_read_unlock();
  54                         pr_err("failed to find OPP for %ld\n", freq_Hz);
  55                         return PTR_ERR(opp);
  56                 }
  57                 volt = dev_pm_opp_get_voltage(opp);
  58                 rcu_read_unlock();
  59                 tol = volt * voltage_tolerance / 100;
  60                 volt_old = regulator_get_voltage(cpu_reg);
  61         }
  62
  63         pr_debug("%u MHz, %ld mV --> %u MHz, %ld mV\n",
  64                  old_freq / 1000, volt_old ? volt_old / 1000 : -1,
  65                  new_freq / 1000, volt ? volt / 1000 : -1);
  66
  67         /* scaling up?  scale voltage before frequency */
  68         if (!IS_ERR(cpu_reg) && new_freq > old_freq) {
  69                 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
  70                 if (ret) {
  71                         pr_err("failed to scale voltage up: %d\n", ret);
  72                         return ret;
  73                 }
  74         }
  75
  76         ret = clk_set_rate(cpu_clk, freq_exact);
  77         if (ret) {
  78                 pr_err("failed to set clock rate: %d\n", ret);
  79                 if (!IS_ERR(cpu_reg))
  80                         regulator_set_voltage_tol(cpu_reg, volt_old, tol);
  81                 return ret;
  82         }
  83
  84         /* scaling down?  scale voltage after frequency */
  85         if (!IS_ERR(cpu_reg) && new_freq < old_freq) {
  86                 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
  87                 if (ret) {
  88                         pr_err("failed to scale voltage down: %d\n", ret);
  89                         clk_set_rate(cpu_clk, old_freq * 1000);
  90                 }
  91         }
  92
  93         return ret;
  94 }
  95
  96 static int cpu0_cpufreq_init(struct cpufreq_policy *policy)
  97 {
  98         policy->clk = cpu_clk;
  99         return cpufreq_generic_init(policy, freq_table, transition_latency);
 100 }
 101
 102 static struct cpufreq_driver cpu0_cpufreq_driver = {
 103         .flags = CPUFREQ_STICKY,
 104         .verify = cpufreq_generic_frequency_table_verify,
 105         .target_index = cpu0_set_target,
 106         .get = cpufreq_generic_get,
 107         .init = cpu0_cpufreq_init,
 108         .exit = cpufreq_generic_exit,
 109         .name = "generic_cpu0",
 110         .attr = cpufreq_generic_attr,
 111 };
 112
 113 static int cpu0_cpufreq_probe(struct platform_device *pdev)
 114 {
 115         struct device_node *np;
 116         int ret;
 117
 118         cpu_dev = get_cpu_device(0);
 119         if (!cpu_dev) {
 120                 pr_err("failed to get cpu0 device\n");
 121                 return -ENODEV;
 122         }
 123
 124         np = of_node_get(cpu_dev->of_node);
 125         if (!np) {
 126                 pr_err("failed to find cpu0 node\n");
 127                 return -ENOENT;
 128         }
 129
 130         cpu_reg = devm_regulator_get_optional(cpu_dev, "cpu0");
 131         if (IS_ERR(cpu_reg)) {
 132                 /*
 133                  * If cpu0 regulator supply node is present, but regulator is
 134                  * not yet registered, we should try defering probe.
 135                  */
 136                 if (PTR_ERR(cpu_reg) == -EPROBE_DEFER) {
 137                         dev_err(cpu_dev, "cpu0 regulator not ready, retry\n");
 138                         ret = -EPROBE_DEFER;
 139                         goto out_put_node;
 140                 }
 141                 pr_warn("failed to get cpu0 regulator: %ld\n",
 142                         PTR_ERR(cpu_reg));
 143         }
 144
 145         cpu_clk = devm_clk_get(cpu_dev, NULL);
 146         if (IS_ERR(cpu_clk)) {
 147                 ret = PTR_ERR(cpu_clk);
 148                 pr_err("failed to get cpu0 clock: %d\n", ret);
 149                 goto out_put_node;
 150         }
 151
 152         ret = of_init_opp_table(cpu_dev);
 153         if (ret) {
 154                 pr_err("failed to init OPP table: %d\n", ret);
 155                 goto out_put_node;
 156         }
 157
 158         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
 159         if (ret) {
 160                 pr_err("failed to init cpufreq table: %d\n", ret);
 161                 goto out_put_node;
 162         }
 163
 164         of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
 165
 166         if (of_property_read_u32(np, "clock-latency", &transition_latency))
 167                 transition_latency = CPUFREQ_ETERNAL;
 168
 169         if (!IS_ERR(cpu_reg)) {
 170                 struct dev_pm_opp *opp;
 171                 unsigned long min_uV, max_uV;
 172                 int i;
 173
 174                 /*
 175                  * OPP is maintained in order of increasing frequency, and
 176                  * freq_table initialised from OPP is therefore sorted in the
 177                  * same order.
 178                  */
 179                 for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
 180                         ;
 181                 rcu_read_lock();
 182                 opp = dev_pm_opp_find_freq_exact(cpu_dev,
 183                                 freq_table[0].frequency * 1000, true);
 184                 min_uV = dev_pm_opp_get_voltage(opp);
 185                 opp = dev_pm_opp_find_freq_exact(cpu_dev,
 186                                 freq_table[i-1].frequency * 1000, true);
 187                 max_uV = dev_pm_opp_get_voltage(opp);
 188                 rcu_read_unlock();
 189                 ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
 190                 if (ret > 0)
 191                         transition_latency += ret * 1000;
 192         }
 193
 194         ret = cpufreq_register_driver(&cpu0_cpufreq_driver);
 195         if (ret) {
 196                 pr_err("failed register driver: %d\n", ret);
 197                 goto out_free_table;
 198         }
 199
 200         of_node_put(np);
 201         return 0;
 202
 203 out_free_table:
 204         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
 205 out_put_node:
 206         of_node_put(np);
 207         return ret;
 208 }
 209
 210 static int cpu0_cpufreq_remove(struct platform_device *pdev)
 211 {
 212         cpufreq_unregister_driver(&cpu0_cpufreq_driver);
 213         dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
 214
 215         return 0;
 216 }
 217
 218 static struct platform_driver cpu0_cpufreq_platdrv = {
 219         .driver = {
 220                 .name   = "cpufreq-cpu0",
 221                 .owner  = THIS_MODULE,
 222         },
 223         .probe          = cpu0_cpufreq_probe,
 224         .remove         = cpu0_cpufreq_remove,
 225 };
 226 module_platform_driver(cpu0_cpufreq_platdrv);
 227
 228 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
 229 MODULE_DESCRIPTION("Generic CPU0 cpufreq driver");
 230 MODULE_LICENSE("GPL");