drivers/cpufreq/s3c2440-cpufreq.c

   1 /*
   2  * Copyright (c) 2006-2009 Simtec Electronics
   3  *      http://armlinux.simtec.co.uk/
   4  *      Ben Dooks <ben@simtec.co.uk>
   5  *      Vincent Sanders <vince@simtec.co.uk>
   6  *
   7  * S3C2440/S3C2442 CPU Frequency scaling
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12 */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/init.h>
  17 #include <linux/module.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/ioport.h>
  20 #include <linux/cpufreq.h>
  21 #include <linux/device.h>
  22 #include <linux/delay.h>
  23 #include <linux/clk.h>
  24 #include <linux/err.h>
  25 #include <linux/io.h>
  26
  27 #include <asm/mach/arch.h>
  28 #include <asm/mach/map.h>
  29
  30 #include <mach/regs-clock.h>
  31
  32 #include <plat/cpu.h>
  33 #include <plat/cpu-freq-core.h>
  34
  35 static struct clk *xtal;
  36 static struct clk *fclk;
  37 static struct clk *hclk;
  38 static struct clk *armclk;
  39
  40 /* HDIV: 1, 2, 3, 4, 6, 8 */
  41
  42 static inline int within_khz(unsigned long a, unsigned long b)
  43 {
  44         long diff = a - b;
  45
  46         return (diff >= -1000 && diff <= 1000);
  47 }
  48
  49 /**
  50  * s3c2440_cpufreq_calcdivs - calculate divider settings
  51  * @cfg: The cpu frequency settings.
  52  *
  53  * Calcualte the divider values for the given frequency settings
  54  * specified in @cfg. The values are stored in @cfg for later use
  55  * by the relevant set routine if the request settings can be reached.
  56  */
  57 static int s3c2440_cpufreq_calcdivs(struct s3c_cpufreq_config *cfg)
  58 {
  59         unsigned int hdiv, pdiv;
  60         unsigned long hclk, fclk, armclk;
  61         unsigned long hclk_max;
  62
  63         fclk = cfg->freq.fclk;
  64         armclk = cfg->freq.armclk;
  65         hclk_max = cfg->max.hclk;
  66
  67         s3c_freq_dbg("%s: fclk is %lu, armclk %lu, max hclk %lu\n",
  68                      __func__, fclk, armclk, hclk_max);
  69
  70         if (armclk > fclk) {
  71                 pr_warn("%s: armclk > fclk\n", __func__);
  72                 armclk = fclk;
  73         }
  74
  75         /* if we are in DVS, we need HCLK to be <= ARMCLK */
  76         if (armclk < fclk && armclk < hclk_max)
  77                 hclk_max = armclk;
  78
  79         for (hdiv = 1; hdiv < 9; hdiv++) {
  80                 if (hdiv == 5 || hdiv == 7)
  81                         hdiv++;
  82
  83                 hclk = (fclk / hdiv);
  84                 if (hclk <= hclk_max || within_khz(hclk, hclk_max))
  85                         break;
  86         }
  87
  88         s3c_freq_dbg("%s: hclk %lu, div %d\n", __func__, hclk, hdiv);
  89
  90         if (hdiv > 8)
  91                 goto invalid;
  92
  93         pdiv = (hclk > cfg->max.pclk) ? 2 : 1;
  94
  95         if ((hclk / pdiv) > cfg->max.pclk)
  96                 pdiv++;
  97
  98         s3c_freq_dbg("%s: pdiv %d\n", __func__, pdiv);
  99
 100         if (pdiv > 2)
 101                 goto invalid;
 102
 103         pdiv *= hdiv;
 104
 105         /* calculate a valid armclk */
 106
 107         if (armclk < hclk)
 108                 armclk = hclk;
 109
 110         /* if we're running armclk lower than fclk, this really means
 111          * that the system should go into dvs mode, which means that
 112          * armclk is connected to hclk. */
 113         if (armclk < fclk) {
 114                 cfg->divs.dvs = 1;
 115                 armclk = hclk;
 116         } else
 117                 cfg->divs.dvs = 0;
 118
 119         cfg->freq.armclk = armclk;
 120
 121         /* store the result, and then return */
 122
 123         cfg->divs.h_divisor = hdiv;
 124         cfg->divs.p_divisor = pdiv;
 125
 126         return 0;
 127
 128  invalid:
 129         return -EINVAL;
 130 }
 131
 132 #define CAMDIVN_HCLK_HALF (S3C2440_CAMDIVN_HCLK3_HALF | \
 133                            S3C2440_CAMDIVN_HCLK4_HALF)
 134
 135 /**
 136  * s3c2440_cpufreq_setdivs - set the cpu frequency divider settings
 137  * @cfg: The cpu frequency settings.
 138  *
 139  * Set the divisors from the settings in @cfg, which where generated
 140  * during the calculation phase by s3c2440_cpufreq_calcdivs().
 141  */
 142 static void s3c2440_cpufreq_setdivs(struct s3c_cpufreq_config *cfg)
 143 {
 144         unsigned long clkdiv, camdiv;
 145
 146         s3c_freq_dbg("%s: divisors: h=%d, p=%d\n", __func__,
 147                      cfg->divs.h_divisor, cfg->divs.p_divisor);
 148
 149         clkdiv = __raw_readl(S3C2410_CLKDIVN);
 150         camdiv = __raw_readl(S3C2440_CAMDIVN);
 151
 152         clkdiv &= ~(S3C2440_CLKDIVN_HDIVN_MASK | S3C2440_CLKDIVN_PDIVN);
 153         camdiv &= ~CAMDIVN_HCLK_HALF;
 154
 155         switch (cfg->divs.h_divisor) {
 156         case 1:
 157                 clkdiv |= S3C2440_CLKDIVN_HDIVN_1;
 158                 break;
 159
 160         case 2:
 161                 clkdiv |= S3C2440_CLKDIVN_HDIVN_2;
 162                 break;
 163
 164         case 6:
 165                 camdiv |= S3C2440_CAMDIVN_HCLK3_HALF;
 166         case 3:
 167                 clkdiv |= S3C2440_CLKDIVN_HDIVN_3_6;
 168                 break;
 169
 170         case 8:
 171                 camdiv |= S3C2440_CAMDIVN_HCLK4_HALF;
 172         case 4:
 173                 clkdiv |= S3C2440_CLKDIVN_HDIVN_4_8;
 174                 break;
 175
 176         default:
 177                 BUG();  /* we don't expect to get here. */
 178         }
 179
 180         if (cfg->divs.p_divisor != cfg->divs.h_divisor)
 181                 clkdiv |= S3C2440_CLKDIVN_PDIVN;
 182
 183         /* todo - set pclk. */
 184
 185         /* Write the divisors first with hclk intentionally halved so that
 186          * when we write clkdiv we will under-frequency instead of over. We
 187          * then make a short delay and remove the hclk halving if necessary.
 188          */
 189
 190         __raw_writel(camdiv | CAMDIVN_HCLK_HALF, S3C2440_CAMDIVN);
 191         __raw_writel(clkdiv, S3C2410_CLKDIVN);
 192
 193         ndelay(20);
 194         __raw_writel(camdiv, S3C2440_CAMDIVN);
 195
 196         clk_set_parent(armclk, cfg->divs.dvs ? hclk : fclk);
 197 }
 198
 199 static int run_freq_for(unsigned long max_hclk, unsigned long fclk,
 200                         int *divs,
 201                         struct cpufreq_frequency_table *table,
 202                         size_t table_size)
 203 {
 204         unsigned long freq;
 205         int index = 0;
 206         int div;
 207
 208         for (div = *divs; div > 0; div = *divs++) {
 209                 freq = fclk / div;
 210
 211                 if (freq > max_hclk && div != 1)
 212                         continue;
 213
 214                 freq /= 1000; /* table is in kHz */
 215                 index = s3c_cpufreq_addfreq(table, index, table_size, freq);
 216                 if (index < 0)
 217                         break;
 218         }
 219
 220         return index;
 221 }
 222
 223 static int hclk_divs[] = { 1, 2, 3, 4, 6, 8, -1 };
 224
 225 static int s3c2440_cpufreq_calctable(struct s3c_cpufreq_config *cfg,
 226                                      struct cpufreq_frequency_table *table,
 227                                      size_t table_size)
 228 {
 229         int ret;
 230
 231         WARN_ON(cfg->info == NULL);
 232         WARN_ON(cfg->board == NULL);
 233
 234         ret = run_freq_for(cfg->info->max.hclk,
 235                            cfg->info->max.fclk,
 236                            hclk_divs,
 237                            table, table_size);
 238
 239         s3c_freq_dbg("%s: returning %d\n", __func__, ret);
 240
 241         return ret;
 242 }
 243
 244 static struct s3c_cpufreq_info s3c2440_cpufreq_info = {
 245         .max            = {
 246                 .fclk   = 400000000,
 247                 .hclk   = 133333333,
 248                 .pclk   =  66666666,
 249         },
 250
 251         .locktime_m     = 300,
 252         .locktime_u     = 300,
 253         .locktime_bits  = 16,
 254
 255         .name           = "s3c244x",
 256         .calc_iotiming  = s3c2410_iotiming_calc,
 257         .set_iotiming   = s3c2410_iotiming_set,
 258         .get_iotiming   = s3c2410_iotiming_get,
 259         .set_fvco       = s3c2410_set_fvco,
 260
 261         .set_refresh    = s3c2410_cpufreq_setrefresh,
 262         .set_divs       = s3c2440_cpufreq_setdivs,
 263         .calc_divs      = s3c2440_cpufreq_calcdivs,
 264         .calc_freqtable = s3c2440_cpufreq_calctable,
 265
 266         .debug_io_show  = s3c_cpufreq_debugfs_call(s3c2410_iotiming_debugfs),
 267 };
 268
 269 static int s3c2440_cpufreq_add(struct device *dev,
 270                                struct subsys_interface *sif)
 271 {
 272         xtal = s3c_cpufreq_clk_get(NULL, "xtal");
 273         hclk = s3c_cpufreq_clk_get(NULL, "hclk");
 274         fclk = s3c_cpufreq_clk_get(NULL, "fclk");
 275         armclk = s3c_cpufreq_clk_get(NULL, "armclk");
 276
 277         if (IS_ERR(xtal) || IS_ERR(hclk) || IS_ERR(fclk) || IS_ERR(armclk)) {
 278                 pr_err("%s: failed to get clocks\n", __func__);
 279                 return -ENOENT;
 280         }
 281
 282         return s3c_cpufreq_register(&s3c2440_cpufreq_info);
 283 }
 284
 285 static struct subsys_interface s3c2440_cpufreq_interface = {
 286         .name           = "s3c2440_cpufreq",
 287         .subsys         = &s3c2440_subsys,
 288         .add_dev        = s3c2440_cpufreq_add,
 289 };
 290
 291 static int s3c2440_cpufreq_init(void)
 292 {
 293         return subsys_interface_register(&s3c2440_cpufreq_interface);
 294 }
 295
 296 /* arch_initcall adds the clocks we need, so use subsys_initcall. */
 297 subsys_initcall(s3c2440_cpufreq_init);
 298
 299 static struct subsys_interface s3c2442_cpufreq_interface = {
 300         .name           = "s3c2442_cpufreq",
 301         .subsys         = &s3c2442_subsys,
 302         .add_dev        = s3c2440_cpufreq_add,
 303 };
 304
 305 static int s3c2442_cpufreq_init(void)
 306 {
 307         return subsys_interface_register(&s3c2442_cpufreq_interface);
 308 }
 309 subsys_initcall(s3c2442_cpufreq_init);