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/opp.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 freq_Hz, volt = 0, volt_old = 0, tol = 0;
  48         unsigned int index, cpu;
  49         int ret;
  50
  51         ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
  52                                              relation, &index);
  53         if (ret) {
  54                 pr_err("failed to match target freqency %d: %d\n",
  55                        target_freq, ret);
  56                 return ret;
  57         }
  58
  59         freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
  60         if (freq_Hz < 0)
  61                 freq_Hz = freq_table[index].frequency * 1000;
  62         freqs.new = freq_Hz / 1000;
  63         freqs.old = clk_get_rate(cpu_clk) / 1000;
  64
  65         if (freqs.old == freqs.new)
  66                 return 0;
  67
  68         for_each_online_cpu(cpu) {
  69                 freqs.cpu = cpu;
  70                 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  71         }
  72
  73         if (cpu_reg) {
  74                 opp = opp_find_freq_ceil(cpu_dev, &freq_Hz);
  75                 if (IS_ERR(opp)) {
  76                         pr_err("failed to find OPP for %ld\n", freq_Hz);
  77                         return PTR_ERR(opp);
  78                 }
  79                 volt = opp_get_voltage(opp);
  80                 tol = volt * voltage_tolerance / 100;
  81                 volt_old = regulator_get_voltage(cpu_reg);
  82         }
  83
  84         pr_debug("%u MHz, %ld mV --> %u MHz, %ld mV\n",
  85                  freqs.old / 1000, volt_old ? volt_old / 1000 : -1,
  86                  freqs.new / 1000, volt ? volt / 1000 : -1);
  87
  88         /* scaling up?  scale voltage before frequency */
  89         if (cpu_reg && freqs.new > freqs.old) {
  90                 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
  91                 if (ret) {
  92                         pr_err("failed to scale voltage up: %d\n", ret);
  93                         freqs.new = freqs.old;
  94                         return ret;
  95                 }
  96         }
  97
  98         ret = clk_set_rate(cpu_clk, freqs.new * 1000);
  99         if (ret) {
 100                 pr_err("failed to set clock rate: %d\n", ret);
 101                 if (cpu_reg)
 102                         regulator_set_voltage_tol(cpu_reg, volt_old, tol);
 103                 return ret;
 104         }
 105
 106         /* scaling down?  scale voltage after frequency */
 107         if (cpu_reg && freqs.new < freqs.old) {
 108                 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
 109                 if (ret) {
 110                         pr_err("failed to scale voltage down: %d\n", ret);
 111                         clk_set_rate(cpu_clk, freqs.old * 1000);
 112                         freqs.new = freqs.old;
 113                         return ret;
 114                 }
 115         }
 116
 117         for_each_online_cpu(cpu) {
 118                 freqs.cpu = cpu;
 119                 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 120         }
 121
 122         return 0;
 123 }
 124
 125 static int cpu0_cpufreq_init(struct cpufreq_policy *policy)
 126 {
 127         int ret;
 128
 129         if (policy->cpu != 0)
 130                 return -EINVAL;
 131
 132         ret = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 133         if (ret) {
 134                 pr_err("invalid frequency table: %d\n", ret);
 135                 return ret;
 136         }
 137
 138         policy->cpuinfo.transition_latency = transition_latency;
 139         policy->cur = clk_get_rate(cpu_clk) / 1000;
 140
 141         /*
 142          * The driver only supports the SMP configuartion where all processors
 143          * share the clock and voltage and clock.  Use cpufreq affected_cpus
 144          * interface to have all CPUs scaled together.
 145          */
 146         policy->shared_type = CPUFREQ_SHARED_TYPE_ANY;
 147         cpumask_setall(policy->cpus);
 148
 149         cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 150
 151         return 0;
 152 }
 153
 154 static int cpu0_cpufreq_exit(struct cpufreq_policy *policy)
 155 {
 156         cpufreq_frequency_table_put_attr(policy->cpu);
 157
 158         return 0;
 159 }
 160
 161 static struct freq_attr *cpu0_cpufreq_attr[] = {
 162         &cpufreq_freq_attr_scaling_available_freqs,
 163         NULL,
 164 };
 165
 166 static struct cpufreq_driver cpu0_cpufreq_driver = {
 167         .flags = CPUFREQ_STICKY,
 168         .verify = cpu0_verify_speed,
 169         .target = cpu0_set_target,
 170         .get = cpu0_get_speed,
 171         .init = cpu0_cpufreq_init,
 172         .exit = cpu0_cpufreq_exit,
 173         .name = "generic_cpu0",
 174         .attr = cpu0_cpufreq_attr,
 175 };
 176
 177 static int cpu0_cpufreq_driver_init(void)
 178 {
 179         struct device_node *np;
 180         int ret;
 181
 182         np = of_find_node_by_path("/cpus/cpu@0");
 183         if (!np) {
 184                 pr_err("failed to find cpu0 node\n");
 185                 return -ENOENT;
 186         }
 187
 188         cpu_dev = get_cpu_device(0);
 189         if (!cpu_dev) {
 190                 pr_err("failed to get cpu0 device\n");
 191                 ret = -ENODEV;
 192                 goto out_put_node;
 193         }
 194
 195         cpu_dev->of_node = np;
 196
 197         cpu_clk = clk_get(cpu_dev, NULL);
 198         if (IS_ERR(cpu_clk)) {
 199                 ret = PTR_ERR(cpu_clk);
 200                 pr_err("failed to get cpu0 clock: %d\n", ret);
 201                 goto out_put_node;
 202         }
 203
 204         cpu_reg = regulator_get(cpu_dev, "cpu0");
 205         if (IS_ERR(cpu_reg)) {
 206                 pr_warn("failed to get cpu0 regulator\n");
 207                 cpu_reg = NULL;
 208         }
 209
 210         ret = of_init_opp_table(cpu_dev);
 211         if (ret) {
 212                 pr_err("failed to init OPP table: %d\n", ret);
 213                 goto out_put_node;
 214         }
 215
 216         ret = opp_init_cpufreq_table(cpu_dev, &freq_table);
 217         if (ret) {
 218                 pr_err("failed to init cpufreq table: %d\n", ret);
 219                 goto out_put_node;
 220         }
 221
 222         of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
 223
 224         if (of_property_read_u32(np, "clock-latency", &transition_latency))
 225                 transition_latency = CPUFREQ_ETERNAL;
 226
 227         if (cpu_reg) {
 228                 struct opp *opp;
 229                 unsigned long min_uV, max_uV;
 230                 int i;
 231
 232                 /*
 233                  * OPP is maintained in order of increasing frequency, and
 234                  * freq_table initialised from OPP is therefore sorted in the
 235                  * same order.
 236                  */
 237                 for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
 238                         ;
 239                 opp = opp_find_freq_exact(cpu_dev,
 240                                 freq_table[0].frequency * 1000, true);
 241                 min_uV = opp_get_voltage(opp);
 242                 opp = opp_find_freq_exact(cpu_dev,
 243                                 freq_table[i-1].frequency * 1000, true);
 244                 max_uV = opp_get_voltage(opp);
 245                 ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
 246                 if (ret > 0)
 247                         transition_latency += ret * 1000;
 248         }
 249
 250         ret = cpufreq_register_driver(&cpu0_cpufreq_driver);
 251         if (ret) {
 252                 pr_err("failed register driver: %d\n", ret);
 253                 goto out_free_table;
 254         }
 255
 256         of_node_put(np);
 257         return 0;
 258
 259 out_free_table:
 260         opp_free_cpufreq_table(cpu_dev, &freq_table);
 261 out_put_node:
 262         of_node_put(np);
 263         return ret;
 264 }
 265 late_initcall(cpu0_cpufreq_driver_init);
 266
 267 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
 268 MODULE_DESCRIPTION("Generic CPU0 cpufreq driver");
 269 MODULE_LICENSE("GPL");