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/cpufreq.h>
  16 #include <linux/err.h>
  17 #include <linux/module.h>
  18 #include <linux/of.h>
  19 #include <linux/opp.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/regulator/consumer.h>
  22 #include <linux/slab.h>
  23
  24 static unsigned int transition_latency;
  25 static unsigned int voltage_tolerance; /* in percentage */
  26
  27 static struct device *cpu_dev;
  28 static struct clk *cpu_clk;
  29 static struct regulator *cpu_reg;
  30 static struct cpufreq_frequency_table *freq_table;
  31
  32 static int cpu0_verify_speed(struct cpufreq_policy *policy)
  33 {
  34         return cpufreq_frequency_table_verify(policy, freq_table);
  35 }
  36
  37 static unsigned int cpu0_get_speed(unsigned int cpu)
  38 {
  39         return clk_get_rate(cpu_clk) / 1000;
  40 }
  41
  42 static int cpu0_set_target(struct cpufreq_policy *policy,
  43                            unsigned int target_freq, unsigned int relation)
  44 {
  45         struct cpufreq_freqs freqs;
  46         struct opp *opp;
  47         unsigned long volt = 0, volt_old = 0, tol = 0;
  48         long freq_Hz, freq_exact;
  49         unsigned int index;
  50         int ret;
  51
  52         ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
  53                                              relation, &index);
  54         if (ret) {
  55                 pr_err("failed to match target freqency %d: %d\n",
  56                        target_freq, ret);
  57                 return ret;
  58         }
  59
  60         freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
  61         if (freq_Hz < 0)
  62                 freq_Hz = freq_table[index].frequency * 1000;
  63         freq_exact = freq_Hz;
  64         freqs.new = freq_Hz / 1000;
  65         freqs.old = clk_get_rate(cpu_clk) / 1000;
  66
  67         if (freqs.old == freqs.new)
  68                 return 0;
  69
  70         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  71
  72         if (cpu_reg) {
  73                 rcu_read_lock();
  74                 opp = opp_find_freq_ceil(cpu_dev, &freq_Hz);
  75                 if (IS_ERR(opp)) {
  76                         rcu_read_unlock();
  77                         pr_err("failed to find OPP for %ld\n", freq_Hz);
  78                         freqs.new = freqs.old;
  79                         ret = PTR_ERR(opp);
  80                         goto post_notify;
  81                 }
  82                 volt = opp_get_voltage(opp);
  83                 rcu_read_unlock();
  84                 tol = volt * voltage_tolerance / 100;
  85                 volt_old = regulator_get_voltage(cpu_reg);
  86         }
  87
  88         pr_debug("%u MHz, %ld mV --> %u MHz, %ld mV\n",
  89                  freqs.old / 1000, volt_old ? volt_old / 1000 : -1,
  90                  freqs.new / 1000, volt ? volt / 1000 : -1);
  91
  92         /* scaling up?  scale voltage before frequency */
  93         if (cpu_reg && freqs.new > freqs.old) {
  94                 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
  95                 if (ret) {
  96                         pr_err("failed to scale voltage up: %d\n", ret);
  97                         freqs.new = freqs.old;
  98                         goto post_notify;
  99                 }
 100         }
 101
 102         ret = clk_set_rate(cpu_clk, freq_exact);
 103         if (ret) {
 104                 pr_err("failed to set clock rate: %d\n", ret);
 105                 if (cpu_reg)
 106                         regulator_set_voltage_tol(cpu_reg, volt_old, tol);
 107                 freqs.new = freqs.old;
 108                 goto post_notify;
 109         }
 110
 111         /* scaling down?  scale voltage after frequency */
 112         if (cpu_reg && freqs.new < freqs.old) {
 113                 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
 114                 if (ret) {
 115                         pr_err("failed to scale voltage down: %d\n", ret);
 116                         clk_set_rate(cpu_clk, freqs.old * 1000);
 117                         freqs.new = freqs.old;
 118                 }
 119         }
 120
 121 post_notify:
 122         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 123
 124         return ret;
 125 }
 126
 127 static int cpu0_cpufreq_init(struct cpufreq_policy *policy)
 128 {
 129         int ret;
 130
 131         ret = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 132         if (ret) {
 133                 pr_err("invalid frequency table: %d\n", ret);
 134                 return ret;
 135         }
 136
 137         policy->cpuinfo.transition_latency = transition_latency;
 138         policy->cur = clk_get_rate(cpu_clk) / 1000;
 139
 140         /*
 141          * The driver only supports the SMP configuartion where all processors
 142          * share the clock and voltage and clock.  Use cpufreq affected_cpus
 143          * interface to have all CPUs scaled together.
 144          */
 145         cpumask_setall(policy->cpus);
 146
 147         cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 148
 149         return 0;
 150 }
 151
 152 static int cpu0_cpufreq_exit(struct cpufreq_policy *policy)
 153 {
 154         cpufreq_frequency_table_put_attr(policy->cpu);
 155
 156         return 0;
 157 }
 158
 159 static struct freq_attr *cpu0_cpufreq_attr[] = {
 160         &cpufreq_freq_attr_scaling_available_freqs,
 161         NULL,
 162 };
 163
 164 static struct cpufreq_driver cpu0_cpufreq_driver = {
 165         .flags = CPUFREQ_STICKY,
 166         .verify = cpu0_verify_speed,
 167         .target = cpu0_set_target,
 168         .get = cpu0_get_speed,
 169         .init = cpu0_cpufreq_init,
 170         .exit = cpu0_cpufreq_exit,
 171         .name = "generic_cpu0",
 172         .attr = cpu0_cpufreq_attr,
 173 };
 174
 175 static int cpu0_cpufreq_probe(struct platform_device *pdev)
 176 {
 177         struct device_node *np, *parent;
 178         int ret;
 179
 180         parent = of_find_node_by_path("/cpus");
 181         if (!parent) {
 182                 pr_err("failed to find OF /cpus\n");
 183                 return -ENOENT;
 184         }
 185
 186         for_each_child_of_node(parent, np) {
 187                 if (of_get_property(np, "operating-points", NULL))
 188                         break;
 189         }
 190
 191         if (!np) {
 192                 pr_err("failed to find cpu0 node\n");
 193                 ret = -ENOENT;
 194                 goto out_put_parent;
 195         }
 196
 197         cpu_dev = &pdev->dev;
 198         cpu_dev->of_node = np;
 199
 200         cpu_reg = devm_regulator_get(cpu_dev, "cpu0");
 201         if (IS_ERR(cpu_reg)) {
 202                 /*
 203                  * If cpu0 regulator supply node is present, but regulator is
 204                  * not yet registered, we should try defering probe.
 205                  */
 206                 if (PTR_ERR(cpu_reg) == -EPROBE_DEFER) {
 207                         dev_err(cpu_dev, "cpu0 regulator not ready, retry\n");
 208                         ret = -EPROBE_DEFER;
 209                         goto out_put_node;
 210                 }
 211                 pr_warn("failed to get cpu0 regulator: %ld\n",
 212                         PTR_ERR(cpu_reg));
 213                 cpu_reg = NULL;
 214         }
 215
 216         cpu_clk = devm_clk_get(cpu_dev, NULL);
 217         if (IS_ERR(cpu_clk)) {
 218                 ret = PTR_ERR(cpu_clk);
 219                 pr_err("failed to get cpu0 clock: %d\n", ret);
 220                 goto out_put_node;
 221         }
 222
 223         ret = of_init_opp_table(cpu_dev);
 224         if (ret) {
 225                 pr_err("failed to init OPP table: %d\n", ret);
 226                 goto out_put_node;
 227         }
 228
 229         ret = opp_init_cpufreq_table(cpu_dev, &freq_table);
 230         if (ret) {
 231                 pr_err("failed to init cpufreq table: %d\n", ret);
 232                 goto out_put_node;
 233         }
 234
 235         of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
 236
 237         if (of_property_read_u32(np, "clock-latency", &transition_latency))
 238                 transition_latency = CPUFREQ_ETERNAL;
 239
 240         if (cpu_reg) {
 241                 struct opp *opp;
 242                 unsigned long min_uV, max_uV;
 243                 int i;
 244
 245                 /*
 246                  * OPP is maintained in order of increasing frequency, and
 247                  * freq_table initialised from OPP is therefore sorted in the
 248                  * same order.
 249                  */
 250                 for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
 251                         ;
 252                 rcu_read_lock();
 253                 opp = opp_find_freq_exact(cpu_dev,
 254                                 freq_table[0].frequency * 1000, true);
 255                 min_uV = opp_get_voltage(opp);
 256                 opp = opp_find_freq_exact(cpu_dev,
 257                                 freq_table[i-1].frequency * 1000, true);
 258                 max_uV = opp_get_voltage(opp);
 259                 rcu_read_unlock();
 260                 ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
 261                 if (ret > 0)
 262                         transition_latency += ret * 1000;
 263         }
 264
 265         ret = cpufreq_register_driver(&cpu0_cpufreq_driver);
 266         if (ret) {
 267                 pr_err("failed register driver: %d\n", ret);
 268                 goto out_free_table;
 269         }
 270
 271         of_node_put(np);
 272         of_node_put(parent);
 273         return 0;
 274
 275 out_free_table:
 276         opp_free_cpufreq_table(cpu_dev, &freq_table);
 277 out_put_node:
 278         of_node_put(np);
 279 out_put_parent:
 280         of_node_put(parent);
 281         return ret;
 282 }
 283
 284 static int cpu0_cpufreq_remove(struct platform_device *pdev)
 285 {
 286         cpufreq_unregister_driver(&cpu0_cpufreq_driver);
 287         opp_free_cpufreq_table(cpu_dev, &freq_table);
 288
 289         return 0;
 290 }
 291
 292 static struct platform_driver cpu0_cpufreq_platdrv = {
 293         .driver = {
 294                 .name   = "cpufreq-cpu0",
 295                 .owner  = THIS_MODULE,
 296         },
 297         .probe          = cpu0_cpufreq_probe,
 298         .remove         = cpu0_cpufreq_remove,
 299 };
 300 module_platform_driver(cpu0_cpufreq_platdrv);
 301
 302 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
 303 MODULE_DESCRIPTION("Generic CPU0 cpufreq driver");
 304 MODULE_LICENSE("GPL");