drivers/cpufreq/s3c64xx-cpufreq.c

   1 /*
   2  * Copyright 2009 Wolfson Microelectronics plc
   3  *
   4  * S3C64xx CPUfreq Support
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #define pr_fmt(fmt) "cpufreq: " fmt
  12
  13 #include <linux/kernel.h>
  14 #include <linux/types.h>
  15 #include <linux/init.h>
  16 #include <linux/cpufreq.h>
  17 #include <linux/clk.h>
  18 #include <linux/err.h>
  19 #include <linux/regulator/consumer.h>
  20 #include <linux/module.h>
  21
  22 static struct clk *armclk;
  23 static struct regulator *vddarm;
  24 static unsigned long regulator_latency;
  25
  26 #ifdef CONFIG_CPU_S3C6410
  27 struct s3c64xx_dvfs {
  28         unsigned int vddarm_min;
  29         unsigned int vddarm_max;
  30 };
  31
  32 static struct s3c64xx_dvfs s3c64xx_dvfs_table[] = {
  33         [0] = { 1000000, 1150000 },
  34         [1] = { 1050000, 1150000 },
  35         [2] = { 1100000, 1150000 },
  36         [3] = { 1200000, 1350000 },
  37         [4] = { 1300000, 1350000 },
  38 };
  39
  40 static struct cpufreq_frequency_table s3c64xx_freq_table[] = {
  41         { 0,  66000 },
  42         { 0, 100000 },
  43         { 0, 133000 },
  44         { 1, 200000 },
  45         { 1, 222000 },
  46         { 1, 266000 },
  47         { 2, 333000 },
  48         { 2, 400000 },
  49         { 2, 532000 },
  50         { 2, 533000 },
  51         { 3, 667000 },
  52         { 4, 800000 },
  53         { 0, CPUFREQ_TABLE_END },
  54 };
  55 #endif
  56
  57 static int s3c64xx_cpufreq_verify_speed(struct cpufreq_policy *policy)
  58 {
  59         if (policy->cpu != 0)
  60                 return -EINVAL;
  61
  62         return cpufreq_frequency_table_verify(policy, s3c64xx_freq_table);
  63 }
  64
  65 static unsigned int s3c64xx_cpufreq_get_speed(unsigned int cpu)
  66 {
  67         if (cpu != 0)
  68                 return 0;
  69
  70         return clk_get_rate(armclk) / 1000;
  71 }
  72
  73 static int s3c64xx_cpufreq_set_target(struct cpufreq_policy *policy,
  74                                       unsigned int target_freq,
  75                                       unsigned int relation)
  76 {
  77         int ret;
  78         unsigned int i;
  79         struct cpufreq_freqs freqs;
  80         struct s3c64xx_dvfs *dvfs;
  81
  82         ret = cpufreq_frequency_table_target(policy, s3c64xx_freq_table,
  83                                              target_freq, relation, &i);
  84         if (ret != 0)
  85                 return ret;
  86
  87         freqs.cpu = 0;
  88         freqs.old = clk_get_rate(armclk) / 1000;
  89         freqs.new = s3c64xx_freq_table[i].frequency;
  90         freqs.flags = 0;
  91         dvfs = &s3c64xx_dvfs_table[s3c64xx_freq_table[i].index];
  92
  93         if (freqs.old == freqs.new)
  94                 return 0;
  95
  96         pr_debug("Transition %d-%dkHz\n", freqs.old, freqs.new);
  97
  98         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  99
 100 #ifdef CONFIG_REGULATOR
 101         if (vddarm && freqs.new > freqs.old) {
 102                 ret = regulator_set_voltage(vddarm,
 103                                             dvfs->vddarm_min,
 104                                             dvfs->vddarm_max);
 105                 if (ret != 0) {
 106                         pr_err("Failed to set VDDARM for %dkHz: %d\n",
 107                                freqs.new, ret);
 108                         goto err;
 109                 }
 110         }
 111 #endif
 112
 113         ret = clk_set_rate(armclk, freqs.new * 1000);
 114         if (ret < 0) {
 115                 pr_err("Failed to set rate %dkHz: %d\n",
 116                        freqs.new, ret);
 117                 goto err;
 118         }
 119
 120         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 121
 122 #ifdef CONFIG_REGULATOR
 123         if (vddarm && freqs.new < freqs.old) {
 124                 ret = regulator_set_voltage(vddarm,
 125                                             dvfs->vddarm_min,
 126                                             dvfs->vddarm_max);
 127                 if (ret != 0) {
 128                         pr_err("Failed to set VDDARM for %dkHz: %d\n",
 129                                freqs.new, ret);
 130                         goto err_clk;
 131                 }
 132         }
 133 #endif
 134
 135         pr_debug("Set actual frequency %lukHz\n",
 136                  clk_get_rate(armclk) / 1000);
 137
 138         return 0;
 139
 140 err_clk:
 141         if (clk_set_rate(armclk, freqs.old * 1000) < 0)
 142                 pr_err("Failed to restore original clock rate\n");
 143 err:
 144         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 145
 146         return ret;
 147 }
 148
 149 #ifdef CONFIG_REGULATOR
 150 static void __init s3c64xx_cpufreq_config_regulator(void)
 151 {
 152         int count, v, i, found;
 153         struct cpufreq_frequency_table *freq;
 154         struct s3c64xx_dvfs *dvfs;
 155
 156         count = regulator_count_voltages(vddarm);
 157         if (count < 0) {
 158                 pr_err("Unable to check supported voltages\n");
 159         }
 160
 161         freq = s3c64xx_freq_table;
 162         while (count > 0 && freq->frequency != CPUFREQ_TABLE_END) {
 163                 if (freq->frequency == CPUFREQ_ENTRY_INVALID)
 164                         continue;
 165
 166                 dvfs = &s3c64xx_dvfs_table[freq->index];
 167                 found = 0;
 168
 169                 for (i = 0; i < count; i++) {
 170                         v = regulator_list_voltage(vddarm, i);
 171                         if (v >= dvfs->vddarm_min && v <= dvfs->vddarm_max)
 172                                 found = 1;
 173                 }
 174
 175                 if (!found) {
 176                         pr_debug("%dkHz unsupported by regulator\n",
 177                                  freq->frequency);
 178                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 179                 }
 180
 181                 freq++;
 182         }
 183
 184         /* Guess based on having to do an I2C/SPI write; in future we
 185          * will be able to query the regulator performance here. */
 186         regulator_latency = 1 * 1000 * 1000;
 187 }
 188 #endif
 189
 190 static int s3c64xx_cpufreq_driver_init(struct cpufreq_policy *policy)
 191 {
 192         int ret;
 193         struct cpufreq_frequency_table *freq;
 194
 195         if (policy->cpu != 0)
 196                 return -EINVAL;
 197
 198         if (s3c64xx_freq_table == NULL) {
 199                 pr_err("No frequency information for this CPU\n");
 200                 return -ENODEV;
 201         }
 202
 203         armclk = clk_get(NULL, "armclk");
 204         if (IS_ERR(armclk)) {
 205                 pr_err("Unable to obtain ARMCLK: %ld\n",
 206                        PTR_ERR(armclk));
 207                 return PTR_ERR(armclk);
 208         }
 209
 210 #ifdef CONFIG_REGULATOR
 211         vddarm = regulator_get(NULL, "vddarm");
 212         if (IS_ERR(vddarm)) {
 213                 ret = PTR_ERR(vddarm);
 214                 pr_err("Failed to obtain VDDARM: %d\n", ret);
 215                 pr_err("Only frequency scaling available\n");
 216                 vddarm = NULL;
 217         } else {
 218                 s3c64xx_cpufreq_config_regulator();
 219         }
 220 #endif
 221
 222         freq = s3c64xx_freq_table;
 223         while (freq->frequency != CPUFREQ_TABLE_END) {
 224                 unsigned long r;
 225
 226                 /* Check for frequencies we can generate */
 227                 r = clk_round_rate(armclk, freq->frequency * 1000);
 228                 r /= 1000;
 229                 if (r != freq->frequency) {
 230                         pr_debug("%dkHz unsupported by clock\n",
 231                                  freq->frequency);
 232                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 233                 }
 234
 235                 /* If we have no regulator then assume startup
 236                  * frequency is the maximum we can support. */
 237                 if (!vddarm && freq->frequency > s3c64xx_cpufreq_get_speed(0))
 238                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 239
 240                 freq++;
 241         }
 242
 243         policy->cur = clk_get_rate(armclk) / 1000;
 244
 245         /* Datasheet says PLL stabalisation time (if we were to use
 246          * the PLLs, which we don't currently) is ~300us worst case,
 247          * but add some fudge.
 248          */
 249         policy->cpuinfo.transition_latency = (500 * 1000) + regulator_latency;
 250
 251         ret = cpufreq_frequency_table_cpuinfo(policy, s3c64xx_freq_table);
 252         if (ret != 0) {
 253                 pr_err("Failed to configure frequency table: %d\n",
 254                        ret);
 255                 regulator_put(vddarm);
 256                 clk_put(armclk);
 257         }
 258
 259         return ret;
 260 }
 261
 262 static struct cpufreq_driver s3c64xx_cpufreq_driver = {
 263         .owner          = THIS_MODULE,
 264         .flags          = 0,
 265         .verify         = s3c64xx_cpufreq_verify_speed,
 266         .target         = s3c64xx_cpufreq_set_target,
 267         .get            = s3c64xx_cpufreq_get_speed,
 268         .init           = s3c64xx_cpufreq_driver_init,
 269         .name           = "s3c",
 270 };
 271
 272 static int __init s3c64xx_cpufreq_init(void)
 273 {
 274         return cpufreq_register_driver(&s3c64xx_cpufreq_driver);
 275 }
 276 module_init(s3c64xx_cpufreq_init);