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