arch/arm/mach-sa1100/cpu-sa1110.c

   1 /*
   2  *  linux/arch/arm/mach-sa1100/cpu-sa1110.c
   3  *
   4  *  Copyright (C) 2001 Russell King
   5  *
   6  *  $Id: cpu-sa1110.c,v 1.9 2002/07/06 16:53:18 rmk Exp $
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * Note: there are two erratas that apply to the SA1110 here:
  13  *  7 - SDRAM auto-power-up failure (rev A0)
  14  * 13 - Corruption of internal register reads/writes following
  15  *      SDRAM reads (rev A0, B0, B1)
  16  *
  17  * We ignore rev. A0 and B0 devices; I don't think they're worth supporting.
  18  *
  19  * The SDRAM type can be passed on the command line as cpu_sa1110.sdram=type
  20  */
  21 #include <linux/moduleparam.h>
  22 #include <linux/types.h>
  23 #include <linux/kernel.h>
  24 #include <linux/sched.h>
  25 #include <linux/cpufreq.h>
  26 #include <linux/delay.h>
  27 #include <linux/init.h>
  28
  29 #include <asm/hardware.h>
  30 #include <asm/mach-types.h>
  31 #include <asm/io.h>
  32 #include <asm/system.h>
  33
  34 #include "generic.h"
  35
  36 #undef DEBUG
  37
  38 static struct cpufreq_driver sa1110_driver;
  39
  40 struct sdram_params {
  41         const char name[16];
  42         u_char  rows;           /* bits                          */
  43         u_char  cas_latency;    /* cycles                        */
  44         u_char  tck;            /* clock cycle time (ns)         */
  45         u_char  trcd;           /* activate to r/w (ns)          */
  46         u_char  trp;            /* precharge to activate (ns)    */
  47         u_char  twr;            /* write recovery time (ns)      */
  48         u_short refresh;        /* refresh time for array (us)   */
  49 };
  50
  51 struct sdram_info {
  52         u_int   mdcnfg;
  53         u_int   mdrefr;
  54         u_int   mdcas[3];
  55 };
  56
  57 static struct sdram_params sdram_tbl[] __initdata = {
  58         {       /* Toshiba TC59SM716 CL2 */
  59                 .name           = "TC59SM716-CL2",
  60                 .rows           = 12,
  61                 .tck            = 10,
  62                 .trcd           = 20,
  63                 .trp            = 20,
  64                 .twr            = 10,
  65                 .refresh        = 64000,
  66                 .cas_latency    = 2,
  67         }, {    /* Toshiba TC59SM716 CL3 */
  68                 .name           = "TC59SM716-CL3",
  69                 .rows           = 12,
  70                 .tck            = 8,
  71                 .trcd           = 20,
  72                 .trp            = 20,
  73                 .twr            = 8,
  74                 .refresh        = 64000,
  75                 .cas_latency    = 3,
  76         }, {    /* Samsung K4S641632D TC75 */
  77                 .name           = "K4S641632D",
  78                 .rows           = 14,
  79                 .tck            = 9,
  80                 .trcd           = 27,
  81                 .trp            = 20,
  82                 .twr            = 9,
  83                 .refresh        = 64000,
  84                 .cas_latency    = 3,
  85         }, {    /* Samsung K4S281632B-1H */
  86                 .name           = "K4S281632B-1H",
  87                 .rows           = 12,
  88                 .tck            = 10,
  89                 .trp            = 20,
  90                 .twr            = 10,
  91                 .refresh        = 64000,
  92                 .cas_latency    = 3,
  93         }, {    /* Samsung KM416S4030CT */
  94                 .name           = "KM416S4030CT",
  95                 .rows           = 13,
  96                 .tck            = 8,
  97                 .trcd           = 24,   /* 3 CLKs */
  98                 .trp            = 24,   /* 3 CLKs */
  99                 .twr            = 16,   /* Trdl: 2 CLKs */
 100                 .refresh        = 64000,
 101                 .cas_latency    = 3,
 102         }, {    /* Winbond W982516AH75L CL3 */
 103                 .name           = "W982516AH75L",
 104                 .rows           = 16,
 105                 .tck            = 8,
 106                 .trcd           = 20,
 107                 .trp            = 20,
 108                 .twr            = 8,
 109                 .refresh        = 64000,
 110                 .cas_latency    = 3,
 111         },
 112 };
 113
 114 static struct sdram_params sdram_params;
 115
 116 /*
 117  * Given a period in ns and frequency in khz, calculate the number of
 118  * cycles of frequency in period.  Note that we round up to the next
 119  * cycle, even if we are only slightly over.
 120  */
 121 static inline u_int ns_to_cycles(u_int ns, u_int khz)
 122 {
 123         return (ns * khz + 999999) / 1000000;
 124 }
 125
 126 /*
 127  * Create the MDCAS register bit pattern.
 128  */
 129 static inline void set_mdcas(u_int *mdcas, int delayed, u_int rcd)
 130 {
 131         u_int shift;
 132
 133         rcd = 2 * rcd - 1;
 134         shift = delayed + 1 + rcd;
 135
 136         mdcas[0]  = (1 << rcd) - 1;
 137         mdcas[0] |= 0x55555555 << shift;
 138         mdcas[1]  = mdcas[2] = 0x55555555 << (shift & 1);
 139 }
 140
 141 static void
 142 sdram_calculate_timing(struct sdram_info *sd, u_int cpu_khz,
 143                        struct sdram_params *sdram)
 144 {
 145         u_int mem_khz, sd_khz, trp, twr;
 146
 147         mem_khz = cpu_khz / 2;
 148         sd_khz = mem_khz;
 149
 150         /*
 151          * If SDCLK would invalidate the SDRAM timings,
 152          * run SDCLK at half speed.
 153          *
 154          * CPU steppings prior to B2 must either run the memory at
 155          * half speed or use delayed read latching (errata 13).
 156          */
 157         if ((ns_to_cycles(sdram->tck, sd_khz) > 1) ||
 158             (CPU_REVISION < CPU_SA1110_B2 && sd_khz < 62000))
 159                 sd_khz /= 2;
 160
 161         sd->mdcnfg = MDCNFG & 0x007f007f;
 162
 163         twr = ns_to_cycles(sdram->twr, mem_khz);
 164
 165         /* trp should always be >1 */
 166         trp = ns_to_cycles(sdram->trp, mem_khz) - 1;
 167         if (trp < 1)
 168                 trp = 1;
 169
 170         sd->mdcnfg |= trp << 8;
 171         sd->mdcnfg |= trp << 24;
 172         sd->mdcnfg |= sdram->cas_latency << 12;
 173         sd->mdcnfg |= sdram->cas_latency << 28;
 174         sd->mdcnfg |= twr << 14;
 175         sd->mdcnfg |= twr << 30;
 176
 177         sd->mdrefr = MDREFR & 0xffbffff0;
 178         sd->mdrefr |= 7;
 179
 180         if (sd_khz != mem_khz)
 181                 sd->mdrefr |= MDREFR_K1DB2;
 182
 183         /* initial number of '1's in MDCAS + 1 */
 184         set_mdcas(sd->mdcas, sd_khz >= 62000, ns_to_cycles(sdram->trcd, mem_khz));
 185
 186 #ifdef DEBUG
 187         printk("MDCNFG: %08x MDREFR: %08x MDCAS0: %08x MDCAS1: %08x MDCAS2: %08x\n",
 188                 sd->mdcnfg, sd->mdrefr, sd->mdcas[0], sd->mdcas[1], sd->mdcas[2]);
 189 #endif
 190 }
 191
 192 /*
 193  * Set the SDRAM refresh rate.
 194  */
 195 static inline void sdram_set_refresh(u_int dri)
 196 {
 197         MDREFR = (MDREFR & 0xffff000f) | (dri << 4);
 198         (void) MDREFR;
 199 }
 200
 201 /*
 202  * Update the refresh period.  We do this such that we always refresh
 203  * the SDRAMs within their permissible period.  The refresh period is
 204  * always a multiple of the memory clock (fixed at cpu_clock / 2).
 205  *
 206  * FIXME: we don't currently take account of burst accesses here,
 207  * but neither do Intels DM nor Angel.
 208  */
 209 static void
 210 sdram_update_refresh(u_int cpu_khz, struct sdram_params *sdram)
 211 {
 212         u_int ns_row = (sdram->refresh * 1000) >> sdram->rows;
 213         u_int dri = ns_to_cycles(ns_row, cpu_khz / 2) / 32;
 214
 215 #ifdef DEBUG
 216         mdelay(250);
 217         printk("new dri value = %d\n", dri);
 218 #endif
 219
 220         sdram_set_refresh(dri);
 221 }
 222
 223 /*
 224  * Ok, set the CPU frequency.
 225  */
 226 static int sa1110_target(struct cpufreq_policy *policy,
 227                          unsigned int target_freq,
 228                          unsigned int relation)
 229 {
 230         struct sdram_params *sdram = &sdram_params;
 231         struct cpufreq_freqs freqs;
 232         struct sdram_info sd;
 233         unsigned long flags;
 234         unsigned int ppcr, unused;
 235
 236         switch(relation){
 237         case CPUFREQ_RELATION_L:
 238                 ppcr = sa11x0_freq_to_ppcr(target_freq);
 239                 if (sa11x0_ppcr_to_freq(ppcr) > policy->max)
 240                         ppcr--;
 241                 break;
 242         case CPUFREQ_RELATION_H:
 243                 ppcr = sa11x0_freq_to_ppcr(target_freq);
 244                 if (ppcr && (sa11x0_ppcr_to_freq(ppcr) > target_freq) &&
 245                     (sa11x0_ppcr_to_freq(ppcr-1) >= policy->min))
 246                         ppcr--;
 247                 break;
 248         default:
 249                 return -EINVAL;
 250         }
 251
 252         freqs.old = sa11x0_getspeed(0);
 253         freqs.new = sa11x0_ppcr_to_freq(ppcr);
 254         freqs.cpu = 0;
 255
 256         sdram_calculate_timing(&sd, freqs.new, sdram);
 257
 258 #if 0
 259         /*
 260          * These values are wrong according to the SA1110 documentation
 261          * and errata, but they seem to work.  Need to get a storage
 262          * scope on to the SDRAM signals to work out why.
 263          */
 264         if (policy->max < 147500) {
 265                 sd.mdrefr |= MDREFR_K1DB2;
 266                 sd.mdcas[0] = 0xaaaaaa7f;
 267         } else {
 268                 sd.mdrefr &= ~MDREFR_K1DB2;
 269                 sd.mdcas[0] = 0xaaaaaa9f;
 270         }
 271         sd.mdcas[1] = 0xaaaaaaaa;
 272         sd.mdcas[2] = 0xaaaaaaaa;
 273 #endif
 274
 275         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 276
 277         /*
 278          * The clock could be going away for some time.  Set the SDRAMs
 279          * to refresh rapidly (every 64 memory clock cycles).  To get
 280          * through the whole array, we need to wait 262144 mclk cycles.
 281          * We wait 20ms to be safe.
 282          */
 283         sdram_set_refresh(2);
 284         if (!irqs_disabled()) {
 285                 msleep(20);
 286         } else {
 287                 mdelay(20);
 288         }
 289
 290         /*
 291          * Reprogram the DRAM timings with interrupts disabled, and
 292          * ensure that we are doing this within a complete cache line.
 293          * This means that we won't access SDRAM for the duration of
 294          * the programming.
 295          */
 296         local_irq_save(flags);
 297         asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (0));
 298         udelay(10);
 299         __asm__ __volatile__("                                  \n\
 300                 b       2f                                      \n\
 301                 .align  5                                       \n\
 302 1:              str     %3, [%1, #0]            @ MDCNFG        \n\
 303                 str     %4, [%1, #28]           @ MDREFR        \n\
 304                 str     %5, [%1, #4]            @ MDCAS0        \n\
 305                 str     %6, [%1, #8]            @ MDCAS1        \n\
 306                 str     %7, [%1, #12]           @ MDCAS2        \n\
 307                 str     %8, [%2, #0]            @ PPCR          \n\
 308                 ldr     %0, [%1, #0]                            \n\
 309                 b       3f                                      \n\
 310 2:              b       1b                                      \n\
 311 3:              nop                                             \n\
 312                 nop"
 313                 : "=&r" (unused)
 314                 : "r" (&MDCNFG), "r" (&PPCR), "0" (sd.mdcnfg),
 315                   "r" (sd.mdrefr), "r" (sd.mdcas[0]),
 316                   "r" (sd.mdcas[1]), "r" (sd.mdcas[2]), "r" (ppcr));
 317         local_irq_restore(flags);
 318
 319         /*
 320          * Now, return the SDRAM refresh back to normal.
 321          */
 322         sdram_update_refresh(freqs.new, sdram);
 323
 324         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 325
 326         return 0;
 327 }
 328
 329 static int __init sa1110_cpu_init(struct cpufreq_policy *policy)
 330 {
 331         if (policy->cpu != 0)
 332                 return -EINVAL;
 333         policy->cur = policy->min = policy->max = sa11x0_getspeed(0);
 334         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 335         policy->cpuinfo.min_freq = 59000;
 336         policy->cpuinfo.max_freq = 287000;
 337         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 338         return 0;
 339 }
 340
 341 static struct cpufreq_driver sa1110_driver = {
 342         .flags          = CPUFREQ_STICKY,
 343         .verify         = sa11x0_verify_speed,
 344         .target         = sa1110_target,
 345         .get            = sa11x0_getspeed,
 346         .init           = sa1110_cpu_init,
 347         .name           = "sa1110",
 348 };
 349
 350 static struct sdram_params *sa1110_find_sdram(const char *name)
 351 {
 352         struct sdram_params *sdram;
 353
 354         for (sdram = sdram_tbl; sdram < sdram_tbl + ARRAY_SIZE(sdram_tbl); sdram++)
 355                 if (strcmp(name, sdram->name) == 0)
 356                         return sdram;
 357
 358         return NULL;
 359 }
 360
 361 static char sdram_name[16];
 362
 363 static int __init sa1110_clk_init(void)
 364 {
 365         struct sdram_params *sdram;
 366         const char *name = sdram_name;
 367
 368         if (!name[0]) {
 369                 if (machine_is_assabet())
 370                         name = "TC59SM716-CL3";
 371
 372                 if (machine_is_pt_system3())
 373                         name = "K4S641632D";
 374
 375                 if (machine_is_h3100())
 376                         name = "KM416S4030CT";
 377                 if (machine_is_jornada720())
 378                         name = "K4S281632B-1H";
 379         }
 380
 381         sdram = sa1110_find_sdram(name);
 382         if (sdram) {
 383                 printk(KERN_DEBUG "SDRAM: tck: %d trcd: %d trp: %d"
 384                         " twr: %d refresh: %d cas_latency: %d\n",
 385                         sdram->tck, sdram->trcd, sdram->trp,
 386                         sdram->twr, sdram->refresh, sdram->cas_latency);
 387
 388                 memcpy(&sdram_params, sdram, sizeof(sdram_params));
 389
 390                 return cpufreq_register_driver(&sa1110_driver);
 391         }
 392
 393         return 0;
 394 }
 395
 396 module_param_string(sdram, sdram_name, sizeof(sdram_name), 0);
 397 arch_initcall(sa1110_clk_init);