arch/arm/mach-s3c2412/cpu-freq.c

   1 /* linux/arch/arm/mach-s3c2412/cpu-freq.c
   2  *
   3  * Copyright 2008 Simtec Electronics
   4  *      http://armlinux.simtec.co.uk/
   5  *      Ben Dooks <ben@simtec.co.uk>
   6  *
   7  * S3C2412 CPU Frequency scalling
   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 <asm/mach/arch.h>
  26 #include <asm/mach/map.h>
  27
  28 #include <mach/regs-clock.h>
  29 #include <mach/regs-s3c2412-mem.h>
  30
  31 #include <plat/cpu.h>
  32 #include <plat/clock.h>
  33 #include <plat/cpu-freq-core.h>
  34
  35 /* our clock resources. */
  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 int s3c2412_cpufreq_calcdivs(struct s3c_cpufreq_config *cfg)
  44 {
  45         unsigned int hdiv, pdiv, armdiv, dvs;
  46         unsigned long hclk, fclk, armclk, armdiv_clk;
  47         unsigned long hclk_max;
  48
  49         fclk = cfg->freq.fclk;
  50         armclk = cfg->freq.armclk;
  51         hclk_max = cfg->max.hclk;
  52
  53         /* We can't run hclk above armclk as at the best we have to
  54          * have armclk and hclk in dvs mode. */
  55
  56         if (hclk_max > armclk)
  57                 hclk_max = armclk;
  58
  59         s3c_freq_dbg("%s: fclk=%lu, armclk=%lu, hclk_max=%lu\n",
  60                      __func__, fclk, armclk, hclk_max);
  61         s3c_freq_dbg("%s: want f=%lu, arm=%lu, h=%lu, p=%lu\n",
  62                      __func__, cfg->freq.fclk, cfg->freq.armclk,
  63                      cfg->freq.hclk, cfg->freq.pclk);
  64
  65         armdiv = fclk / armclk;
  66
  67         if (armdiv < 1)
  68                 armdiv = 1;
  69         if (armdiv > 2)
  70                 armdiv = 2;
  71
  72         cfg->divs.arm_divisor = armdiv;
  73         armdiv_clk = fclk / armdiv;
  74
  75         hdiv = armdiv_clk / hclk_max;
  76         if (hdiv < 1)
  77                 hdiv = 1;
  78
  79         cfg->freq.hclk = hclk = armdiv_clk / hdiv;
  80
  81         /* set dvs depending on whether we reached armclk or not. */
  82         cfg->divs.dvs = dvs = armclk < armdiv_clk;
  83
  84         /* update the actual armclk we achieved. */
  85         cfg->freq.armclk = dvs ? hclk : armdiv_clk;
  86
  87         s3c_freq_dbg("%s: armclk %lu, hclk %lu, armdiv %d, hdiv %d, dvs %d\n",
  88                      __func__, armclk, hclk, armdiv, hdiv, cfg->divs.dvs);
  89
  90         if (hdiv > 4)
  91                 goto invalid;
  92
  93         pdiv = (hclk > cfg->max.pclk) ? 2 : 1;
  94
  95         if ((hclk / pdiv) > cfg->max.pclk)
  96                 pdiv++;
  97
  98         cfg->freq.pclk = hclk / pdiv;
  99
 100         s3c_freq_dbg("%s: pdiv %d\n", __func__, pdiv);
 101
 102         if (pdiv > 2)
 103                 goto invalid;
 104
 105         pdiv *= hdiv;
 106
 107         /* store the result, and then return */
 108
 109         cfg->divs.h_divisor = hdiv * armdiv;
 110         cfg->divs.p_divisor = pdiv * armdiv;
 111
 112         return 0;
 113
 114  invalid:
 115         return -EINVAL;
 116 }
 117
 118 static void s3c2412_cpufreq_setdivs(struct s3c_cpufreq_config *cfg)
 119 {
 120         unsigned long clkdiv;
 121         unsigned long olddiv;
 122
 123         olddiv = clkdiv = __raw_readl(S3C2410_CLKDIVN);
 124
 125         /* clear off current clock info */
 126
 127         clkdiv &= ~S3C2412_CLKDIVN_ARMDIVN;
 128         clkdiv &= ~S3C2412_CLKDIVN_HDIVN_MASK;
 129         clkdiv &= ~S3C2412_CLKDIVN_PDIVN;
 130
 131         if (cfg->divs.arm_divisor == 2)
 132                 clkdiv |= S3C2412_CLKDIVN_ARMDIVN;
 133
 134         clkdiv |= ((cfg->divs.h_divisor / cfg->divs.arm_divisor) - 1);
 135
 136         if (cfg->divs.p_divisor != cfg->divs.h_divisor)
 137                 clkdiv |= S3C2412_CLKDIVN_PDIVN;
 138
 139         s3c_freq_dbg("%s: div %08lx => %08lx\n", __func__, olddiv, clkdiv);
 140         __raw_writel(clkdiv, S3C2410_CLKDIVN);
 141
 142         clk_set_parent(armclk, cfg->divs.dvs ? hclk : fclk);
 143 }
 144
 145 static void s3c2412_cpufreq_setrefresh(struct s3c_cpufreq_config *cfg)
 146 {
 147         struct s3c_cpufreq_board *board = cfg->board;
 148         unsigned long refresh;
 149
 150         s3c_freq_dbg("%s: refresh %u ns, hclk %lu\n", __func__,
 151                      board->refresh, cfg->freq.hclk);
 152
 153         /* Reduce both the refresh time (in ns) and the frequency (in MHz)
 154          * by 10 each to ensure that we do not overflow 32 bit numbers. This
 155          * should work for HCLK up to 133MHz and refresh period up to 30usec.
 156          */
 157
 158         refresh = (board->refresh / 10);
 159         refresh *= (cfg->freq.hclk / 100);
 160         refresh /= (1 * 1000 * 1000);   /* 10^6 */
 161
 162         s3c_freq_dbg("%s: setting refresh 0x%08lx\n", __func__, refresh);
 163         __raw_writel(refresh, S3C2412_REFRESH);
 164 }
 165
 166 /* set the default cpu frequency information, based on an 200MHz part
 167  * as we have no other way of detecting the speed rating in software.
 168  */
 169
 170 static struct s3c_cpufreq_info s3c2412_cpufreq_info = {
 171         .max            = {
 172                 .fclk   = 200000000,
 173                 .hclk   = 100000000,
 174                 .pclk   =  50000000,
 175         },
 176
 177         .latency        = 5000000, /* 5ms */
 178
 179         .locktime_m     = 150,
 180         .locktime_u     = 150,
 181         .locktime_bits  = 16,
 182
 183         .name           = "s3c2412",
 184         .set_refresh    = s3c2412_cpufreq_setrefresh,
 185         .set_divs       = s3c2412_cpufreq_setdivs,
 186         .calc_divs      = s3c2412_cpufreq_calcdivs,
 187
 188         .calc_iotiming  = s3c2412_iotiming_calc,
 189         .set_iotiming   = s3c2412_iotiming_set,
 190         .get_iotiming   = s3c2412_iotiming_get,
 191
 192         .resume_clocks  = s3c2412_setup_clocks,
 193
 194         .debug_io_show  = s3c_cpufreq_debugfs_call(s3c2412_iotiming_debugfs),
 195 };
 196
 197 static int s3c2412_cpufreq_add(struct device *dev,
 198                                struct subsys_interface *sif)
 199 {
 200         unsigned long fclk_rate;
 201
 202         hclk = clk_get(NULL, "hclk");
 203         if (IS_ERR(hclk)) {
 204                 printk(KERN_ERR "%s: cannot find hclk clock\n", __func__);
 205                 return -ENOENT;
 206         }
 207
 208         fclk = clk_get(NULL, "fclk");
 209         if (IS_ERR(fclk)) {
 210                 printk(KERN_ERR "%s: cannot find fclk clock\n", __func__);
 211                 goto err_fclk;
 212         }
 213
 214         fclk_rate = clk_get_rate(fclk);
 215         if (fclk_rate > 200000000) {
 216                 printk(KERN_INFO
 217                        "%s: fclk %ld MHz, assuming 266MHz capable part\n",
 218                        __func__, fclk_rate / 1000000);
 219                 s3c2412_cpufreq_info.max.fclk = 266000000;
 220                 s3c2412_cpufreq_info.max.hclk = 133000000;
 221                 s3c2412_cpufreq_info.max.pclk =  66000000;
 222         }
 223
 224         armclk = clk_get(NULL, "armclk");
 225         if (IS_ERR(armclk)) {
 226                 printk(KERN_ERR "%s: cannot find arm clock\n", __func__);
 227                 goto err_armclk;
 228         }
 229
 230         xtal = clk_get(NULL, "xtal");
 231         if (IS_ERR(xtal)) {
 232                 printk(KERN_ERR "%s: cannot find xtal clock\n", __func__);
 233                 goto err_xtal;
 234         }
 235
 236         return s3c_cpufreq_register(&s3c2412_cpufreq_info);
 237
 238 err_xtal:
 239         clk_put(armclk);
 240 err_armclk:
 241         clk_put(fclk);
 242 err_fclk:
 243         clk_put(hclk);
 244
 245         return -ENOENT;
 246 }
 247
 248 static struct subsys_interface s3c2412_cpufreq_interface = {
 249         .name           = "s3c2412_cpufreq",
 250         .subsys         = &s3c2412_subsys,
 251         .add_dev        = s3c2412_cpufreq_add,
 252 };
 253
 254 static int s3c2412_cpufreq_init(void)
 255 {
 256         return subsys_interface_register(&s3c2412_cpufreq_interface);
 257 }
 258
 259 arch_initcall(s3c2412_cpufreq_init);