arch/arm/plat-s3c64xx/cpufreq.c

   1 /* linux/arch/arm/plat-s3c64xx/cpufreq.c
   2  *
   3  * Copyright 2009 Wolfson Microelectronics plc
   4  *
   5  * S3C64xx CPUfreq Support
   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 #include <linux/kernel.h>
  13 #include <linux/types.h>
  14 #include <linux/init.h>
  15 #include <linux/cpufreq.h>
  16 #include <linux/clk.h>
  17 #include <linux/err.h>
  18 #include <linux/regulator/consumer.h>
  19
  20 static struct clk *armclk;
  21 static struct regulator *vddarm;
  22
  23 #ifdef CONFIG_CPU_S3C6410
  24 struct s3c64xx_dvfs {
  25         unsigned int vddarm_min;
  26         unsigned int vddarm_max;
  27 };
  28
  29 static struct s3c64xx_dvfs s3c64xx_dvfs_table[] = {
  30         [0] = { 1000000, 1000000 },
  31         [1] = { 1000000, 1050000 },
  32         [2] = { 1050000, 1100000 },
  33         [3] = { 1050000, 1150000 },
  34         [4] = { 1250000, 1350000 },
  35 };
  36
  37 static struct cpufreq_frequency_table s3c64xx_freq_table[] = {
  38         { 0,  66000 },
  39         { 0, 133000 },
  40         { 1, 222000 },
  41         { 1, 266000 },
  42         { 2, 333000 },
  43         { 2, 400000 },
  44         { 3, 532000 },
  45         { 3, 533000 },
  46         { 4, 667000 },
  47         { 0, CPUFREQ_TABLE_END },
  48 };
  49 #endif
  50
  51 static int s3c64xx_cpufreq_verify_speed(struct cpufreq_policy *policy)
  52 {
  53         if (policy->cpu != 0)
  54                 return -EINVAL;
  55
  56         return cpufreq_frequency_table_verify(policy, s3c64xx_freq_table);
  57 }
  58
  59 static unsigned int s3c64xx_cpufreq_get_speed(unsigned int cpu)
  60 {
  61         if (cpu != 0)
  62                 return 0;
  63
  64         return clk_get_rate(armclk) / 1000;
  65 }
  66
  67 static int s3c64xx_cpufreq_set_target(struct cpufreq_policy *policy,
  68                                       unsigned int target_freq,
  69                                       unsigned int relation)
  70 {
  71         int ret;
  72         unsigned int i;
  73         struct cpufreq_freqs freqs;
  74         struct s3c64xx_dvfs *dvfs;
  75
  76         ret = cpufreq_frequency_table_target(policy, s3c64xx_freq_table,
  77                                              target_freq, relation, &i);
  78         if (ret != 0)
  79                 return ret;
  80
  81         freqs.cpu = 0;
  82         freqs.old = clk_get_rate(armclk) / 1000;
  83         freqs.new = s3c64xx_freq_table[i].frequency;
  84         freqs.flags = 0;
  85         dvfs = &s3c64xx_dvfs_table[s3c64xx_freq_table[i].index];
  86
  87         if (freqs.old == freqs.new)
  88                 return 0;
  89
  90         pr_debug("cpufreq: Transition %d-%dkHz\n", freqs.old, freqs.new);
  91
  92         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  93
  94 #ifdef CONFIG_REGULATOR
  95         if (vddarm && freqs.new > freqs.old) {
  96                 ret = regulator_set_voltage(vddarm,
  97                                             dvfs->vddarm_min,
  98                                             dvfs->vddarm_max);
  99                 if (ret != 0) {
 100                         pr_err("cpufreq: Failed to set VDDARM for %dkHz: %d\n",
 101                                freqs.new, ret);
 102                         goto err;
 103                 }
 104         }
 105 #endif
 106
 107         ret = clk_set_rate(armclk, freqs.new * 1000);
 108         if (ret < 0) {
 109                 pr_err("cpufreq: Failed to set rate %dkHz: %d\n",
 110                        freqs.new, ret);
 111                 goto err;
 112         }
 113
 114 #ifdef CONFIG_REGULATOR
 115         if (vddarm && freqs.new < freqs.old) {
 116                 ret = regulator_set_voltage(vddarm,
 117                                             dvfs->vddarm_min,
 118                                             dvfs->vddarm_max);
 119                 if (ret != 0) {
 120                         pr_err("cpufreq: Failed to set VDDARM for %dkHz: %d\n",
 121                                freqs.new, ret);
 122                         goto err_clk;
 123                 }
 124         }
 125 #endif
 126
 127         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 128
 129         pr_debug("cpufreq: Set actual frequency %lukHz\n",
 130                  clk_get_rate(armclk) / 1000);
 131
 132         return 0;
 133
 134 err_clk:
 135         if (clk_set_rate(armclk, freqs.old * 1000) < 0)
 136                 pr_err("Failed to restore original clock rate\n");
 137 err:
 138         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 139
 140         return ret;
 141 }
 142
 143 #ifdef CONFIG_REGULATOR
 144 static void __init s3c64xx_cpufreq_constrain_voltages(void)
 145 {
 146         int count, v, i, found;
 147         struct cpufreq_frequency_table *freq;
 148         struct s3c64xx_dvfs *dvfs;
 149
 150         count = regulator_count_voltages(vddarm);
 151         if (count < 0) {
 152                 pr_err("cpufreq: Unable to check supported voltages\n");
 153                 return;
 154         }
 155
 156         freq = s3c64xx_freq_table;
 157         while (freq->frequency != CPUFREQ_TABLE_END) {
 158                 if (freq->frequency == CPUFREQ_ENTRY_INVALID)
 159                         continue;
 160
 161                 dvfs = &s3c64xx_dvfs_table[freq->index];
 162                 found = 0;
 163
 164                 for (i = 0; i < count; i++) {
 165                         v = regulator_list_voltage(vddarm, i);
 166                         if (v >= dvfs->vddarm_min && v <= dvfs->vddarm_max)
 167                                 found = 1;
 168                 }
 169
 170                 if (!found) {
 171                         pr_debug("cpufreq: %dkHz unsupported by regulator\n",
 172                                  freq->frequency);
 173                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 174                 }
 175
 176                 freq++;
 177         }
 178 }
 179 #endif
 180
 181 static int __init s3c64xx_cpufreq_driver_init(struct cpufreq_policy *policy)
 182 {
 183         int ret;
 184         struct cpufreq_frequency_table *freq;
 185
 186         if (policy->cpu != 0)
 187                 return -EINVAL;
 188
 189         if (s3c64xx_freq_table == NULL) {
 190                 pr_err("cpufreq: No frequency information for this CPU\n");
 191                 return -ENODEV;
 192         }
 193
 194         armclk = clk_get(NULL, "armclk");
 195         if (IS_ERR(armclk)) {
 196                 pr_err("cpufreq: Unable to obtain ARMCLK: %ld\n",
 197                        PTR_ERR(armclk));
 198                 return PTR_ERR(armclk);
 199         }
 200
 201 #ifdef CONFIG_REGULATOR
 202         vddarm = regulator_get(NULL, "vddarm");
 203         if (IS_ERR(vddarm)) {
 204                 ret = PTR_ERR(vddarm);
 205                 pr_err("cpufreq: Failed to obtain VDDARM: %d\n", ret);
 206                 pr_err("cpufreq: Only frequency scaling available\n");
 207                 vddarm = NULL;
 208         } else {
 209                 s3c64xx_cpufreq_constrain_voltages();
 210         }
 211 #endif
 212
 213         freq = s3c64xx_freq_table;
 214         while (freq->frequency != CPUFREQ_TABLE_END) {
 215                 unsigned long r;
 216
 217                 /* Check for frequencies we can generate */
 218                 r = clk_round_rate(armclk, freq->frequency * 1000);
 219                 r /= 1000;
 220                 if (r != freq->frequency)
 221                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 222
 223                 /* If we have no regulator then assume startup
 224                  * frequency is the maximum we can support. */
 225                 if (!vddarm && freq->frequency > s3c64xx_cpufreq_get_speed(0))
 226                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 227
 228                 freq++;
 229         }
 230
 231         policy->cur = clk_get_rate(armclk) / 1000;
 232
 233         /* Pick a conservative guess in ns: we'll need ~1 I2C/SPI
 234          * write plus clock reprogramming. */
 235         policy->cpuinfo.transition_latency = 2 * 1000 * 1000;
 236
 237         ret = cpufreq_frequency_table_cpuinfo(policy, s3c64xx_freq_table);
 238         if (ret != 0) {
 239                 pr_err("cpufreq: Failed to configure frequency table: %d\n",
 240                        ret);
 241                 regulator_put(vddarm);
 242                 clk_put(armclk);
 243         }
 244
 245         return ret;
 246 }
 247
 248 static struct cpufreq_driver s3c64xx_cpufreq_driver = {
 249         .owner          = THIS_MODULE,
 250         .flags          = 0,
 251         .verify         = s3c64xx_cpufreq_verify_speed,
 252         .target         = s3c64xx_cpufreq_set_target,
 253         .get            = s3c64xx_cpufreq_get_speed,
 254         .init           = s3c64xx_cpufreq_driver_init,
 255         .name           = "s3c",
 256 };
 257
 258 static int __init s3c64xx_cpufreq_init(void)
 259 {
 260         return cpufreq_register_driver(&s3c64xx_cpufreq_driver);
 261 }
 262 module_init(s3c64xx_cpufreq_init);