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 KM416S4030CT */
  86                 .name           = "KM416S4030CT",
  87                 .rows           = 13,
  88                 .tck            = 8,
  89                 .trcd           = 24,   /* 3 CLKs */
  90                 .trp            = 24,   /* 3 CLKs */
  91                 .twr            = 16,   /* Trdl: 2 CLKs */
  92                 .refresh        = 64000,
  93                 .cas_latency    = 3,
  94         }, {    /* Winbond W982516AH75L CL3 */
  95                 .name           = "W982516AH75L",
  96                 .rows           = 16,
  97                 .tck            = 8,
  98                 .trcd           = 20,
  99                 .trp            = 20,
 100                 .twr            = 8,
 101                 .refresh        = 64000,
 102                 .cas_latency    = 3,
 103         },
 104 };
 105
 106 static struct sdram_params sdram_params;
 107
 108 /*
 109  * Given a period in ns and frequency in khz, calculate the number of
 110  * cycles of frequency in period.  Note that we round up to the next
 111  * cycle, even if we are only slightly over.
 112  */
 113 static inline u_int ns_to_cycles(u_int ns, u_int khz)
 114 {
 115         return (ns * khz + 999999) / 1000000;
 116 }
 117
 118 /*
 119  * Create the MDCAS register bit pattern.
 120  */
 121 static inline void set_mdcas(u_int *mdcas, int delayed, u_int rcd)
 122 {
 123         u_int shift;
 124
 125         rcd = 2 * rcd - 1;
 126         shift = delayed + 1 + rcd;
 127
 128         mdcas[0]  = (1 << rcd) - 1;
 129         mdcas[0] |= 0x55555555 << shift;
 130         mdcas[1]  = mdcas[2] = 0x55555555 << (shift & 1);
 131 }
 132
 133 static void
 134 sdram_calculate_timing(struct sdram_info *sd, u_int cpu_khz,
 135                        struct sdram_params *sdram)
 136 {
 137         u_int mem_khz, sd_khz, trp, twr;
 138
 139         mem_khz = cpu_khz / 2;
 140         sd_khz = mem_khz;
 141
 142         /*
 143          * If SDCLK would invalidate the SDRAM timings,
 144          * run SDCLK at half speed.
 145          *
 146          * CPU steppings prior to B2 must either run the memory at
 147          * half speed or use delayed read latching (errata 13).
 148          */
 149         if ((ns_to_cycles(sdram->tck, sd_khz) > 1) ||
 150             (CPU_REVISION < CPU_SA1110_B2 && sd_khz < 62000))
 151                 sd_khz /= 2;
 152
 153         sd->mdcnfg = MDCNFG & 0x007f007f;
 154
 155         twr = ns_to_cycles(sdram->twr, mem_khz);
 156
 157         /* trp should always be >1 */
 158         trp = ns_to_cycles(sdram->trp, mem_khz) - 1;
 159         if (trp < 1)
 160                 trp = 1;
 161
 162         sd->mdcnfg |= trp << 8;
 163         sd->mdcnfg |= trp << 24;
 164         sd->mdcnfg |= sdram->cas_latency << 12;
 165         sd->mdcnfg |= sdram->cas_latency << 28;
 166         sd->mdcnfg |= twr << 14;
 167         sd->mdcnfg |= twr << 30;
 168
 169         sd->mdrefr = MDREFR & 0xffbffff0;
 170         sd->mdrefr |= 7;
 171
 172         if (sd_khz != mem_khz)
 173                 sd->mdrefr |= MDREFR_K1DB2;
 174
 175         /* initial number of '1's in MDCAS + 1 */
 176         set_mdcas(sd->mdcas, sd_khz >= 62000, ns_to_cycles(sdram->trcd, mem_khz));
 177
 178 #ifdef DEBUG
 179         printk("MDCNFG: %08x MDREFR: %08x MDCAS0: %08x MDCAS1: %08x MDCAS2: %08x\n",
 180                 sd->mdcnfg, sd->mdrefr, sd->mdcas[0], sd->mdcas[1], sd->mdcas[2]);
 181 #endif
 182 }
 183
 184 /*
 185  * Set the SDRAM refresh rate.
 186  */
 187 static inline void sdram_set_refresh(u_int dri)
 188 {
 189         MDREFR = (MDREFR & 0xffff000f) | (dri << 4);
 190         (void) MDREFR;
 191 }
 192
 193 /*
 194  * Update the refresh period.  We do this such that we always refresh
 195  * the SDRAMs within their permissible period.  The refresh period is
 196  * always a multiple of the memory clock (fixed at cpu_clock / 2).
 197  *
 198  * FIXME: we don't currently take account of burst accesses here,
 199  * but neither do Intels DM nor Angel.
 200  */
 201 static void
 202 sdram_update_refresh(u_int cpu_khz, struct sdram_params *sdram)
 203 {
 204         u_int ns_row = (sdram->refresh * 1000) >> sdram->rows;
 205         u_int dri = ns_to_cycles(ns_row, cpu_khz / 2) / 32;
 206
 207 #ifdef DEBUG
 208         mdelay(250);
 209         printk("new dri value = %d\n", dri);
 210 #endif
 211
 212         sdram_set_refresh(dri);
 213 }
 214
 215 /*
 216  * Ok, set the CPU frequency.
 217  */
 218 static int sa1110_target(struct cpufreq_policy *policy,
 219                          unsigned int target_freq,
 220                          unsigned int relation)
 221 {
 222         struct sdram_params *sdram = &sdram_params;
 223         struct cpufreq_freqs freqs;
 224         struct sdram_info sd;
 225         unsigned long flags;
 226         unsigned int ppcr, unused;
 227
 228         switch(relation){
 229         case CPUFREQ_RELATION_L:
 230                 ppcr = sa11x0_freq_to_ppcr(target_freq);
 231                 if (sa11x0_ppcr_to_freq(ppcr) > policy->max)
 232                         ppcr--;
 233                 break;
 234         case CPUFREQ_RELATION_H:
 235                 ppcr = sa11x0_freq_to_ppcr(target_freq);
 236                 if (ppcr && (sa11x0_ppcr_to_freq(ppcr) > target_freq) &&
 237                     (sa11x0_ppcr_to_freq(ppcr-1) >= policy->min))
 238                         ppcr--;
 239                 break;
 240         default:
 241                 return -EINVAL;
 242         }
 243
 244         freqs.old = sa11x0_getspeed(0);
 245         freqs.new = sa11x0_ppcr_to_freq(ppcr);
 246         freqs.cpu = 0;
 247
 248         sdram_calculate_timing(&sd, freqs.new, sdram);
 249
 250 #if 0
 251         /*
 252          * These values are wrong according to the SA1110 documentation
 253          * and errata, but they seem to work.  Need to get a storage
 254          * scope on to the SDRAM signals to work out why.
 255          */
 256         if (policy->max < 147500) {
 257                 sd.mdrefr |= MDREFR_K1DB2;
 258                 sd.mdcas[0] = 0xaaaaaa7f;
 259         } else {
 260                 sd.mdrefr &= ~MDREFR_K1DB2;
 261                 sd.mdcas[0] = 0xaaaaaa9f;
 262         }
 263         sd.mdcas[1] = 0xaaaaaaaa;
 264         sd.mdcas[2] = 0xaaaaaaaa;
 265 #endif
 266
 267         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 268
 269         /*
 270          * The clock could be going away for some time.  Set the SDRAMs
 271          * to refresh rapidly (every 64 memory clock cycles).  To get
 272          * through the whole array, we need to wait 262144 mclk cycles.
 273          * We wait 20ms to be safe.
 274          */
 275         sdram_set_refresh(2);
 276         if (!irqs_disabled()) {
 277                 msleep(20);
 278         } else {
 279                 mdelay(20);
 280         }
 281
 282         /*
 283          * Reprogram the DRAM timings with interrupts disabled, and
 284          * ensure that we are doing this within a complete cache line.
 285          * This means that we won't access SDRAM for the duration of
 286          * the programming.
 287          */
 288         local_irq_save(flags);
 289         asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (0));
 290         udelay(10);
 291         __asm__ __volatile__("                                  \n\
 292                 b       2f                                      \n\
 293                 .align  5                                       \n\
 294 1:              str     %3, [%1, #0]            @ MDCNFG        \n\
 295                 str     %4, [%1, #28]           @ MDREFR        \n\
 296                 str     %5, [%1, #4]            @ MDCAS0        \n\
 297                 str     %6, [%1, #8]            @ MDCAS1        \n\
 298                 str     %7, [%1, #12]           @ MDCAS2        \n\
 299                 str     %8, [%2, #0]            @ PPCR          \n\
 300                 ldr     %0, [%1, #0]                            \n\
 301                 b       3f                                      \n\
 302 2:              b       1b                                      \n\
 303 3:              nop                                             \n\
 304                 nop"
 305                 : "=&r" (unused)
 306                 : "r" (&MDCNFG), "r" (&PPCR), "0" (sd.mdcnfg),
 307                   "r" (sd.mdrefr), "r" (sd.mdcas[0]),
 308                   "r" (sd.mdcas[1]), "r" (sd.mdcas[2]), "r" (ppcr));
 309         local_irq_restore(flags);
 310
 311         /*
 312          * Now, return the SDRAM refresh back to normal.
 313          */
 314         sdram_update_refresh(freqs.new, sdram);
 315
 316         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 317
 318         return 0;
 319 }
 320
 321 static int __init sa1110_cpu_init(struct cpufreq_policy *policy)
 322 {
 323         if (policy->cpu != 0)
 324                 return -EINVAL;
 325         policy->cur = policy->min = policy->max = sa11x0_getspeed(0);
 326         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 327         policy->cpuinfo.min_freq = 59000;
 328         policy->cpuinfo.max_freq = 287000;
 329         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 330         return 0;
 331 }
 332
 333 static struct cpufreq_driver sa1110_driver = {
 334         .flags          = CPUFREQ_STICKY,
 335         .verify         = sa11x0_verify_speed,
 336         .target         = sa1110_target,
 337         .get            = sa11x0_getspeed,
 338         .init           = sa1110_cpu_init,
 339         .name           = "sa1110",
 340 };
 341
 342 static struct sdram_params *sa1110_find_sdram(const char *name)
 343 {
 344         struct sdram_params *sdram;
 345
 346         for (sdram = sdram_tbl; sdram < sdram_tbl + ARRAY_SIZE(sdram_tbl); sdram++)
 347                 if (strcmp(name, sdram->name) == 0)
 348                         return sdram;
 349
 350         return NULL;
 351 }
 352
 353 static char sdram_name[16];
 354
 355 static int __init sa1110_clk_init(void)
 356 {
 357         struct sdram_params *sdram;
 358         const char *name = sdram_name;
 359
 360         if (!name[0]) {
 361                 if (machine_is_assabet())
 362                         name = "TC59SM716-CL3";
 363
 364                 if (machine_is_pt_system3())
 365                         name = "K4S641632D";
 366
 367                 if (machine_is_h3100())
 368                         name = "KM416S4030CT";
 369         }
 370
 371         sdram = sa1110_find_sdram(name);
 372         if (sdram) {
 373                 printk(KERN_DEBUG "SDRAM: tck: %d trcd: %d trp: %d"
 374                         " twr: %d refresh: %d cas_latency: %d\n",
 375                         sdram->tck, sdram->trcd, sdram->trp,
 376                         sdram->twr, sdram->refresh, sdram->cas_latency);
 377
 378                 memcpy(&sdram_params, sdram, sizeof(sdram_params));
 379
 380                 return cpufreq_register_driver(&sa1110_driver);
 381         }
 382
 383         return 0;
 384 }
 385
 386 module_param_string(sdram, sdram_name, sizeof(sdram_name), 0);
 387 arch_initcall(sa1110_clk_init);