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 #include <linux/init.h>
  15 #include <linux/module.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/ioport.h>
  18 #include <linux/cpufreq.h>
  19 #include <linux/device.h>
  20 #include <linux/delay.h>
  21 #include <linux/clk.h>
  22 #include <linux/err.h>
  23 #include <linux/io.h>
  24
  25 #include <mach/hardware.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 #include <plat/clock.h>
  35
  36 static struct clk *xtal;
  37 static struct clk *fclk;
  38 static struct clk *hclk;
  39 static struct clk *armclk;
  40
  41 /* HDIV: 1, 2, 3, 4, 6, 8 */
  42
  43 static inline int within_khz(unsigned long a, unsigned long b)
  44 {
  45         long diff = a - b;
  46
  47         return (diff >= -1000 && diff <= 1000);
  48 }
  49
  50 /**
  51  * s3c2440_cpufreq_calcdivs - calculate divider settings
  52  * @cfg: The cpu frequency settings.
  53  *
  54  * Calcualte the divider values for the given frequency settings
  55  * specified in @cfg. The values are stored in @cfg for later use
  56  * by the relevant set routine if the request settings can be reached.
  57  */
  58 int s3c2440_cpufreq_calcdivs(struct s3c_cpufreq_config *cfg)
  59 {
  60         unsigned int hdiv, pdiv;
  61         unsigned long hclk, fclk, armclk;
  62         unsigned long hclk_max;
  63
  64         fclk = cfg->freq.fclk;
  65         armclk = cfg->freq.armclk;
  66         hclk_max = cfg->max.hclk;
  67
  68         s3c_freq_dbg("%s: fclk is %lu, armclk %lu, max hclk %lu\n",
  69                      __func__, fclk, armclk, hclk_max);
  70
  71         if (armclk > fclk) {
  72                 printk(KERN_WARNING "%s: armclk > fclk\n", __func__);
  73                 armclk = fclk;
  74         }
  75
  76         /* if we are in DVS, we need HCLK to be <= ARMCLK */
  77         if (armclk < fclk && armclk < hclk_max)
  78                 hclk_max = armclk;
  79
  80         for (hdiv = 1; hdiv < 9; hdiv++) {
  81                 if (hdiv == 5 || hdiv == 7)
  82                         hdiv++;
  83
  84                 hclk = (fclk / hdiv);
  85                 if (hclk <= hclk_max || within_khz(hclk, hclk_max))
  86                         break;
  87         }
  88
  89         s3c_freq_dbg("%s: hclk %lu, div %d\n", __func__, hclk, hdiv);
  90
  91         if (hdiv > 8)
  92                 goto invalid;
  93
  94         pdiv = (hclk > cfg->max.pclk) ? 2 : 1;
  95
  96         if ((hclk / pdiv) > cfg->max.pclk)
  97                 pdiv++;
  98
  99         s3c_freq_dbg("%s: pdiv %d\n", __func__, pdiv);
 100
 101         if (pdiv > 2)
 102                 goto invalid;
 103
 104         pdiv *= hdiv;
 105
 106         /* calculate a valid armclk */
 107
 108         if (armclk < hclk)
 109                 armclk = hclk;
 110
 111         /* if we're running armclk lower than fclk, this really means
 112          * that the system should go into dvs mode, which means that
 113          * armclk is connected to hclk. */
 114         if (armclk < fclk) {
 115                 cfg->divs.dvs = 1;
 116                 armclk = hclk;
 117         } else
 118                 cfg->divs.dvs = 0;
 119
 120         cfg->freq.armclk = armclk;
 121
 122         /* store the result, and then return */
 123
 124         cfg->divs.h_divisor = hdiv;
 125         cfg->divs.p_divisor = pdiv;
 126
 127         return 0;
 128
 129  invalid:
 130         return -EINVAL;
 131 }
 132
 133 #define CAMDIVN_HCLK_HALF (S3C2440_CAMDIVN_HCLK3_HALF | \
 134                            S3C2440_CAMDIVN_HCLK4_HALF)
 135
 136 /**
 137  * s3c2440_cpufreq_setdivs - set the cpu frequency divider settings
 138  * @cfg: The cpu frequency settings.
 139  *
 140  * Set the divisors from the settings in @cfg, which where generated
 141  * during the calculation phase by s3c2440_cpufreq_calcdivs().
 142  */
 143 static void s3c2440_cpufreq_setdivs(struct s3c_cpufreq_config *cfg)
 144 {
 145         unsigned long clkdiv, camdiv;
 146
 147         s3c_freq_dbg("%s: divsiors: h=%d, p=%d\n", __func__,
 148                      cfg->divs.h_divisor, cfg->divs.p_divisor);
 149
 150         clkdiv = __raw_readl(S3C2410_CLKDIVN);
 151         camdiv = __raw_readl(S3C2440_CAMDIVN);
 152
 153         clkdiv &= ~(S3C2440_CLKDIVN_HDIVN_MASK | S3C2440_CLKDIVN_PDIVN);
 154         camdiv &= ~CAMDIVN_HCLK_HALF;
 155
 156         switch (cfg->divs.h_divisor) {
 157         case 1:
 158                 clkdiv |= S3C2440_CLKDIVN_HDIVN_1;
 159                 break;
 160
 161         case 2:
 162                 clkdiv |= S3C2440_CLKDIVN_HDIVN_2;
 163                 break;
 164
 165         case 6:
 166                 camdiv |= S3C2440_CAMDIVN_HCLK3_HALF;
 167         case 3:
 168                 clkdiv |= S3C2440_CLKDIVN_HDIVN_3_6;
 169                 break;
 170
 171         case 8:
 172                 camdiv |= S3C2440_CAMDIVN_HCLK4_HALF;
 173         case 4:
 174                 clkdiv |= S3C2440_CLKDIVN_HDIVN_4_8;
 175                 break;
 176
 177         default:
 178                 BUG();  /* we don't expect to get here. */
 179         }
 180
 181         if (cfg->divs.p_divisor != cfg->divs.h_divisor)
 182                 clkdiv |= S3C2440_CLKDIVN_PDIVN;
 183
 184         /* todo - set pclk. */
 185
 186         /* Write the divisors first with hclk intentionally halved so that
 187          * when we write clkdiv we will under-frequency instead of over. We
 188          * then make a short delay and remove the hclk halving if necessary.
 189          */
 190
 191         __raw_writel(camdiv | CAMDIVN_HCLK_HALF, S3C2440_CAMDIVN);
 192         __raw_writel(clkdiv, S3C2410_CLKDIVN);
 193
 194         ndelay(20);
 195         __raw_writel(camdiv, S3C2440_CAMDIVN);
 196
 197         clk_set_parent(armclk, cfg->divs.dvs ? hclk : fclk);
 198 }
 199
 200 static int run_freq_for(unsigned long max_hclk, unsigned long fclk,
 201                         int *divs,
 202                         struct cpufreq_frequency_table *table,
 203                         size_t table_size)
 204 {
 205         unsigned long freq;
 206         int index = 0;
 207         int div;
 208
 209         for (div = *divs; div > 0; div = *divs++) {
 210                 freq = fclk / div;
 211
 212                 if (freq > max_hclk && div != 1)
 213                         continue;
 214
 215                 freq /= 1000; /* table is in kHz */
 216                 index = s3c_cpufreq_addfreq(table, index, table_size, freq);
 217                 if (index < 0)
 218                         break;
 219         }
 220
 221         return index;
 222 }
 223
 224 static int hclk_divs[] = { 1, 2, 3, 4, 6, 8, -1 };
 225
 226 static int s3c2440_cpufreq_calctable(struct s3c_cpufreq_config *cfg,
 227                                      struct cpufreq_frequency_table *table,
 228                                      size_t table_size)
 229 {
 230         int ret;
 231
 232         WARN_ON(cfg->info == NULL);
 233         WARN_ON(cfg->board == NULL);
 234
 235         ret = run_freq_for(cfg->info->max.hclk,
 236                            cfg->info->max.fclk,
 237                            hclk_divs,
 238                            table, table_size);
 239
 240         s3c_freq_dbg("%s: returning %d\n", __func__, ret);
 241
 242         return ret;
 243 }
 244
 245 struct s3c_cpufreq_info s3c2440_cpufreq_info = {
 246         .max            = {
 247                 .fclk   = 400000000,
 248                 .hclk   = 133333333,
 249                 .pclk   =  66666666,
 250         },
 251
 252         .locktime_m     = 300,
 253         .locktime_u     = 300,
 254         .locktime_bits  = 16,
 255
 256         .name           = "s3c244x",
 257         .calc_iotiming  = s3c2410_iotiming_calc,
 258         .set_iotiming   = s3c2410_iotiming_set,
 259         .get_iotiming   = s3c2410_iotiming_get,
 260         .set_fvco       = s3c2410_set_fvco,
 261
 262         .set_refresh    = s3c2410_cpufreq_setrefresh,
 263         .set_divs       = s3c2440_cpufreq_setdivs,
 264         .calc_divs      = s3c2440_cpufreq_calcdivs,
 265         .calc_freqtable = s3c2440_cpufreq_calctable,
 266
 267         .resume_clocks  = s3c244x_setup_clocks,
 268
 269         .debug_io_show  = s3c_cpufreq_debugfs_call(s3c2410_iotiming_debugfs),
 270 };
 271
 272 static int s3c2440_cpufreq_add(struct device *dev,
 273                                struct subsys_interface *sif)
 274 {
 275         xtal = s3c_cpufreq_clk_get(NULL, "xtal");
 276         hclk = s3c_cpufreq_clk_get(NULL, "hclk");
 277         fclk = s3c_cpufreq_clk_get(NULL, "fclk");
 278         armclk = s3c_cpufreq_clk_get(NULL, "armclk");
 279
 280         if (IS_ERR(xtal) || IS_ERR(hclk) || IS_ERR(fclk) || IS_ERR(armclk)) {
 281                 printk(KERN_ERR "%s: failed to get clocks\n", __func__);
 282                 return -ENOENT;
 283         }
 284
 285         return s3c_cpufreq_register(&s3c2440_cpufreq_info);
 286 }
 287
 288 static struct subsys_interface s3c2440_cpufreq_interface = {
 289         .name           = "s3c2440_cpufreq",
 290         .subsys         = &s3c2440_subsys,
 291         .add_dev        = s3c2440_cpufreq_add,
 292 };
 293
 294 static int s3c2440_cpufreq_init(void)
 295 {
 296         return subsys_interface_register(&s3c2440_cpufreq_interface);
 297 }
 298
 299 /* arch_initcall adds the clocks we need, so use subsys_initcall. */
 300 subsys_initcall(s3c2440_cpufreq_init);
 301
 302 static struct subsys_interface s3c2442_cpufreq_interface = {
 303         .name           = "s3c2442_cpufreq",
 304         .subsys         = &s3c2442_subsys,
 305         .add_dev        = s3c2440_cpufreq_add,
 306 };
 307
 308 static int s3c2442_cpufreq_init(void)
 309 {
 310         return subsys_interface_register(&s3c2442_cpufreq_interface);
 311 }
 312 subsys_initcall(s3c2442_cpufreq_init);