drivers/cpufreq/s3c64xx-cpufreq.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright 2009 Wolfson Microelectronics plc
   4  *
   5  * S3C64xx CPUfreq Support
   6  */
   7
   8 #define pr_fmt(fmt) "cpufreq: " fmt
   9
  10 #include <linux/kernel.h>
  11 #include <linux/types.h>
  12 #include <linux/init.h>
  13 #include <linux/cpufreq.h>
  14 #include <linux/clk.h>
  15 #include <linux/err.h>
  16 #include <linux/regulator/consumer.h>
  17 #include <linux/module.h>
  18
  19 static struct regulator *vddarm;
  20 static unsigned long regulator_latency;
  21
  22 #ifdef CONFIG_CPU_S3C6410
  23 struct s3c64xx_dvfs {
  24         unsigned int vddarm_min;
  25         unsigned int vddarm_max;
  26 };
  27
  28 static struct s3c64xx_dvfs s3c64xx_dvfs_table[] = {
  29         [0] = { 1000000, 1150000 },
  30         [1] = { 1050000, 1150000 },
  31         [2] = { 1100000, 1150000 },
  32         [3] = { 1200000, 1350000 },
  33         [4] = { 1300000, 1350000 },
  34 };
  35
  36 static struct cpufreq_frequency_table s3c64xx_freq_table[] = {
  37         { 0, 0,  66000 },
  38         { 0, 0, 100000 },
  39         { 0, 0, 133000 },
  40         { 0, 1, 200000 },
  41         { 0, 1, 222000 },
  42         { 0, 1, 266000 },
  43         { 0, 2, 333000 },
  44         { 0, 2, 400000 },
  45         { 0, 2, 532000 },
  46         { 0, 2, 533000 },
  47         { 0, 3, 667000 },
  48         { 0, 4, 800000 },
  49         { 0, 0, CPUFREQ_TABLE_END },
  50 };
  51 #endif
  52
  53 static int s3c64xx_cpufreq_set_target(struct cpufreq_policy *policy,
  54                                       unsigned int index)
  55 {
  56         struct s3c64xx_dvfs *dvfs;
  57         unsigned int old_freq, new_freq;
  58         int ret;
  59
  60         old_freq = clk_get_rate(policy->clk) / 1000;
  61         new_freq = s3c64xx_freq_table[index].frequency;
  62         dvfs = &s3c64xx_dvfs_table[s3c64xx_freq_table[index].driver_data];
  63
  64 #ifdef CONFIG_REGULATOR
  65         if (vddarm && new_freq > old_freq) {
  66                 ret = regulator_set_voltage(vddarm,
  67                                             dvfs->vddarm_min,
  68                                             dvfs->vddarm_max);
  69                 if (ret != 0) {
  70                         pr_err("Failed to set VDDARM for %dkHz: %d\n",
  71                                new_freq, ret);
  72                         return ret;
  73                 }
  74         }
  75 #endif
  76
  77         ret = clk_set_rate(policy->clk, new_freq * 1000);
  78         if (ret < 0) {
  79                 pr_err("Failed to set rate %dkHz: %d\n",
  80                        new_freq, ret);
  81                 return ret;
  82         }
  83
  84 #ifdef CONFIG_REGULATOR
  85         if (vddarm && new_freq < old_freq) {
  86                 ret = regulator_set_voltage(vddarm,
  87                                             dvfs->vddarm_min,
  88                                             dvfs->vddarm_max);
  89                 if (ret != 0) {
  90                         pr_err("Failed to set VDDARM for %dkHz: %d\n",
  91                                new_freq, ret);
  92                         if (clk_set_rate(policy->clk, old_freq * 1000) < 0)
  93                                 pr_err("Failed to restore original clock rate\n");
  94
  95                         return ret;
  96                 }
  97         }
  98 #endif
  99
 100         pr_debug("Set actual frequency %lukHz\n",
 101                  clk_get_rate(policy->clk) / 1000);
 102
 103         return 0;
 104 }
 105
 106 #ifdef CONFIG_REGULATOR
 107 static void s3c64xx_cpufreq_config_regulator(void)
 108 {
 109         int count, v, i, found;
 110         struct cpufreq_frequency_table *freq;
 111         struct s3c64xx_dvfs *dvfs;
 112
 113         count = regulator_count_voltages(vddarm);
 114         if (count < 0) {
 115                 pr_err("Unable to check supported voltages\n");
 116         }
 117
 118         if (!count)
 119                 goto out;
 120
 121         cpufreq_for_each_valid_entry(freq, s3c64xx_freq_table) {
 122                 dvfs = &s3c64xx_dvfs_table[freq->driver_data];
 123                 found = 0;
 124
 125                 for (i = 0; i < count; i++) {
 126                         v = regulator_list_voltage(vddarm, i);
 127                         if (v >= dvfs->vddarm_min && v <= dvfs->vddarm_max)
 128                                 found = 1;
 129                 }
 130
 131                 if (!found) {
 132                         pr_debug("%dkHz unsupported by regulator\n",
 133                                  freq->frequency);
 134                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 135                 }
 136         }
 137
 138 out:
 139         /* Guess based on having to do an I2C/SPI write; in future we
 140          * will be able to query the regulator performance here. */
 141         regulator_latency = 1 * 1000 * 1000;
 142 }
 143 #endif
 144
 145 static int s3c64xx_cpufreq_driver_init(struct cpufreq_policy *policy)
 146 {
 147         int ret;
 148         struct cpufreq_frequency_table *freq;
 149
 150         if (policy->cpu != 0)
 151                 return -EINVAL;
 152
 153         if (s3c64xx_freq_table == NULL) {
 154                 pr_err("No frequency information for this CPU\n");
 155                 return -ENODEV;
 156         }
 157
 158         policy->clk = clk_get(NULL, "armclk");
 159         if (IS_ERR(policy->clk)) {
 160                 pr_err("Unable to obtain ARMCLK: %ld\n",
 161                        PTR_ERR(policy->clk));
 162                 return PTR_ERR(policy->clk);
 163         }
 164
 165 #ifdef CONFIG_REGULATOR
 166         vddarm = regulator_get(NULL, "vddarm");
 167         if (IS_ERR(vddarm)) {
 168                 ret = PTR_ERR(vddarm);
 169                 pr_err("Failed to obtain VDDARM: %d\n", ret);
 170                 pr_err("Only frequency scaling available\n");
 171                 vddarm = NULL;
 172         } else {
 173                 s3c64xx_cpufreq_config_regulator();
 174         }
 175 #endif
 176
 177         cpufreq_for_each_entry(freq, s3c64xx_freq_table) {
 178                 unsigned long r;
 179
 180                 /* Check for frequencies we can generate */
 181                 r = clk_round_rate(policy->clk, freq->frequency * 1000);
 182                 r /= 1000;
 183                 if (r != freq->frequency) {
 184                         pr_debug("%dkHz unsupported by clock\n",
 185                                  freq->frequency);
 186                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 187                 }
 188
 189                 /* If we have no regulator then assume startup
 190                  * frequency is the maximum we can support. */
 191                 if (!vddarm && freq->frequency > clk_get_rate(policy->clk) / 1000)
 192                         freq->frequency = CPUFREQ_ENTRY_INVALID;
 193         }
 194
 195         /* Datasheet says PLL stabalisation time (if we were to use
 196          * the PLLs, which we don't currently) is ~300us worst case,
 197          * but add some fudge.
 198          */
 199         ret = cpufreq_generic_init(policy, s3c64xx_freq_table,
 200                         (500 * 1000) + regulator_latency);
 201         if (ret != 0) {
 202                 pr_err("Failed to configure frequency table: %d\n",
 203                        ret);
 204                 regulator_put(vddarm);
 205                 clk_put(policy->clk);
 206         }
 207
 208         return ret;
 209 }
 210
 211 static struct cpufreq_driver s3c64xx_cpufreq_driver = {
 212         .flags          = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 213         .verify         = cpufreq_generic_frequency_table_verify,
 214         .target_index   = s3c64xx_cpufreq_set_target,
 215         .get            = cpufreq_generic_get,
 216         .init           = s3c64xx_cpufreq_driver_init,
 217         .name           = "s3c",
 218 };
 219
 220 static int __init s3c64xx_cpufreq_init(void)
 221 {
 222         return cpufreq_register_driver(&s3c64xx_cpufreq_driver);
 223 }
 224 module_init(s3c64xx_cpufreq_init);