drivers/cpufreq/sa1110-cpufreq.c

   1 /*
   2  *  linux/arch/arm/mach-sa1100/cpu-sa1110.c
   3  *
   4  *  Copyright (C) 2001 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Note: there are two erratas that apply to the SA1110 here:
  11  *  7 - SDRAM auto-power-up failure (rev A0)
  12  * 13 - Corruption of internal register reads/writes following
  13  *      SDRAM reads (rev A0, B0, B1)
  14  *
  15  * We ignore rev. A0 and B0 devices; I don't think they're worth supporting.
  16  *
  17  * The SDRAM type can be passed on the command line as cpu_sa1110.sdram=type
  18  */
  19 #include <linux/cpufreq.h>
  20 #include <linux/delay.h>
  21 #include <linux/init.h>
  22 #include <linux/io.h>
  23 #include <linux/kernel.h>
  24 #include <linux/moduleparam.h>
  25 #include <linux/types.h>
  26
  27 #include <asm/cputype.h>
  28 #include <asm/mach-types.h>
  29
  30 #include <mach/generic.h>
  31 #include <mach/hardware.h>
  32
  33 #undef DEBUG
  34
  35 struct sdram_params {
  36         const char name[20];
  37         u_char  rows;           /* bits                          */
  38         u_char  cas_latency;    /* cycles                        */
  39         u_char  tck;            /* clock cycle time (ns)         */
  40         u_char  trcd;           /* activate to r/w (ns)          */
  41         u_char  trp;            /* precharge to activate (ns)    */
  42         u_char  twr;            /* write recovery time (ns)      */
  43         u_short refresh;        /* refresh time for array (us)   */
  44 };
  45
  46 struct sdram_info {
  47         u_int   mdcnfg;
  48         u_int   mdrefr;
  49         u_int   mdcas[3];
  50 };
  51
  52 static struct sdram_params sdram_tbl[] __initdata = {
  53         {       /* Toshiba TC59SM716 CL2 */
  54                 .name           = "TC59SM716-CL2",
  55                 .rows           = 12,
  56                 .tck            = 10,
  57                 .trcd           = 20,
  58                 .trp            = 20,
  59                 .twr            = 10,
  60                 .refresh        = 64000,
  61                 .cas_latency    = 2,
  62         }, {    /* Toshiba TC59SM716 CL3 */
  63                 .name           = "TC59SM716-CL3",
  64                 .rows           = 12,
  65                 .tck            = 8,
  66                 .trcd           = 20,
  67                 .trp            = 20,
  68                 .twr            = 8,
  69                 .refresh        = 64000,
  70                 .cas_latency    = 3,
  71         }, {    /* Samsung K4S641632D TC75 */
  72                 .name           = "K4S641632D",
  73                 .rows           = 14,
  74                 .tck            = 9,
  75                 .trcd           = 27,
  76                 .trp            = 20,
  77                 .twr            = 9,
  78                 .refresh        = 64000,
  79                 .cas_latency    = 3,
  80         }, {    /* Samsung K4S281632B-1H */
  81                 .name           = "K4S281632B-1H",
  82                 .rows           = 12,
  83                 .tck            = 10,
  84                 .trp            = 20,
  85                 .twr            = 10,
  86                 .refresh        = 64000,
  87                 .cas_latency    = 3,
  88         }, {    /* Samsung KM416S4030CT */
  89                 .name           = "KM416S4030CT",
  90                 .rows           = 13,
  91                 .tck            = 8,
  92                 .trcd           = 24,   /* 3 CLKs */
  93                 .trp            = 24,   /* 3 CLKs */
  94                 .twr            = 16,   /* Trdl: 2 CLKs */
  95                 .refresh        = 64000,
  96                 .cas_latency    = 3,
  97         }, {    /* Winbond W982516AH75L CL3 */
  98                 .name           = "W982516AH75L",
  99                 .rows           = 16,
 100                 .tck            = 8,
 101                 .trcd           = 20,
 102                 .trp            = 20,
 103                 .twr            = 8,
 104                 .refresh        = 64000,
 105                 .cas_latency    = 3,
 106         }, {    /* Micron MT48LC8M16A2TG-75 */
 107                 .name           = "MT48LC8M16A2TG-75",
 108                 .rows           = 12,
 109                 .tck            = 8,
 110                 .trcd           = 20,
 111                 .trp            = 20,
 112                 .twr            = 8,
 113                 .refresh        = 64000,
 114                 .cas_latency    = 3,
 115         },
 116 };
 117
 118 static struct sdram_params sdram_params;
 119
 120 /*
 121  * Given a period in ns and frequency in khz, calculate the number of
 122  * cycles of frequency in period.  Note that we round up to the next
 123  * cycle, even if we are only slightly over.
 124  */
 125 static inline u_int ns_to_cycles(u_int ns, u_int khz)
 126 {
 127         return (ns * khz + 999999) / 1000000;
 128 }
 129
 130 /*
 131  * Create the MDCAS register bit pattern.
 132  */
 133 static inline void set_mdcas(u_int *mdcas, int delayed, u_int rcd)
 134 {
 135         u_int shift;
 136
 137         rcd = 2 * rcd - 1;
 138         shift = delayed + 1 + rcd;
 139
 140         mdcas[0]  = (1 << rcd) - 1;
 141         mdcas[0] |= 0x55555555 << shift;
 142         mdcas[1]  = mdcas[2] = 0x55555555 << (shift & 1);
 143 }
 144
 145 static void
 146 sdram_calculate_timing(struct sdram_info *sd, u_int cpu_khz,
 147                        struct sdram_params *sdram)
 148 {
 149         u_int mem_khz, sd_khz, trp, twr;
 150
 151         mem_khz = cpu_khz / 2;
 152         sd_khz = mem_khz;
 153
 154         /*
 155          * If SDCLK would invalidate the SDRAM timings,
 156          * run SDCLK at half speed.
 157          *
 158          * CPU steppings prior to B2 must either run the memory at
 159          * half speed or use delayed read latching (errata 13).
 160          */
 161         if ((ns_to_cycles(sdram->tck, sd_khz) > 1) ||
 162             (CPU_REVISION < CPU_SA1110_B2 && sd_khz < 62000))
 163                 sd_khz /= 2;
 164
 165         sd->mdcnfg = MDCNFG & 0x007f007f;
 166
 167         twr = ns_to_cycles(sdram->twr, mem_khz);
 168
 169         /* trp should always be >1 */
 170         trp = ns_to_cycles(sdram->trp, mem_khz) - 1;
 171         if (trp < 1)
 172                 trp = 1;
 173
 174         sd->mdcnfg |= trp << 8;
 175         sd->mdcnfg |= trp << 24;
 176         sd->mdcnfg |= sdram->cas_latency << 12;
 177         sd->mdcnfg |= sdram->cas_latency << 28;
 178         sd->mdcnfg |= twr << 14;
 179         sd->mdcnfg |= twr << 30;
 180
 181         sd->mdrefr = MDREFR & 0xffbffff0;
 182         sd->mdrefr |= 7;
 183
 184         if (sd_khz != mem_khz)
 185                 sd->mdrefr |= MDREFR_K1DB2;
 186
 187         /* initial number of '1's in MDCAS + 1 */
 188         set_mdcas(sd->mdcas, sd_khz >= 62000,
 189                 ns_to_cycles(sdram->trcd, mem_khz));
 190
 191 #ifdef DEBUG
 192         printk(KERN_DEBUG "MDCNFG: %08x MDREFR: %08x MDCAS0: %08x MDCAS1: %08x MDCAS2: %08x\n",
 193                 sd->mdcnfg, sd->mdrefr, sd->mdcas[0], sd->mdcas[1],
 194                 sd->mdcas[2]);
 195 #endif
 196 }
 197
 198 /*
 199  * Set the SDRAM refresh rate.
 200  */
 201 static inline void sdram_set_refresh(u_int dri)
 202 {
 203         MDREFR = (MDREFR & 0xffff000f) | (dri << 4);
 204         (void) MDREFR;
 205 }
 206
 207 /*
 208  * Update the refresh period.  We do this such that we always refresh
 209  * the SDRAMs within their permissible period.  The refresh period is
 210  * always a multiple of the memory clock (fixed at cpu_clock / 2).
 211  *
 212  * FIXME: we don't currently take account of burst accesses here,
 213  * but neither do Intels DM nor Angel.
 214  */
 215 static void
 216 sdram_update_refresh(u_int cpu_khz, struct sdram_params *sdram)
 217 {
 218         u_int ns_row = (sdram->refresh * 1000) >> sdram->rows;
 219         u_int dri = ns_to_cycles(ns_row, cpu_khz / 2) / 32;
 220
 221 #ifdef DEBUG
 222         mdelay(250);
 223         printk(KERN_DEBUG "new dri value = %d\n", dri);
 224 #endif
 225
 226         sdram_set_refresh(dri);
 227 }
 228
 229 /*
 230  * Ok, set the CPU frequency.
 231  */
 232 static int sa1110_target(struct cpufreq_policy *policy, unsigned int ppcr)
 233 {
 234         struct sdram_params *sdram = &sdram_params;
 235         struct sdram_info sd;
 236         unsigned long flags;
 237         unsigned int unused;
 238
 239         sdram_calculate_timing(&sd, sa11x0_freq_table[ppcr].frequency, sdram);
 240
 241 #if 0
 242         /*
 243          * These values are wrong according to the SA1110 documentation
 244          * and errata, but they seem to work.  Need to get a storage
 245          * scope on to the SDRAM signals to work out why.
 246          */
 247         if (policy->max < 147500) {
 248                 sd.mdrefr |= MDREFR_K1DB2;
 249                 sd.mdcas[0] = 0xaaaaaa7f;
 250         } else {
 251                 sd.mdrefr &= ~MDREFR_K1DB2;
 252                 sd.mdcas[0] = 0xaaaaaa9f;
 253         }
 254         sd.mdcas[1] = 0xaaaaaaaa;
 255         sd.mdcas[2] = 0xaaaaaaaa;
 256 #endif
 257
 258         /*
 259          * The clock could be going away for some time.  Set the SDRAMs
 260          * to refresh rapidly (every 64 memory clock cycles).  To get
 261          * through the whole array, we need to wait 262144 mclk cycles.
 262          * We wait 20ms to be safe.
 263          */
 264         sdram_set_refresh(2);
 265         if (!irqs_disabled())
 266                 msleep(20);
 267         else
 268                 mdelay(20);
 269
 270         /*
 271          * Reprogram the DRAM timings with interrupts disabled, and
 272          * ensure that we are doing this within a complete cache line.
 273          * This means that we won't access SDRAM for the duration of
 274          * the programming.
 275          */
 276         local_irq_save(flags);
 277         asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (0));
 278         udelay(10);
 279         __asm__ __volatile__("\n\
 280                 b       2f                                      \n\
 281                 .align  5                                       \n\
 282 1:              str     %3, [%1, #0]            @ MDCNFG        \n\
 283                 str     %4, [%1, #28]           @ MDREFR        \n\
 284                 str     %5, [%1, #4]            @ MDCAS0        \n\
 285                 str     %6, [%1, #8]            @ MDCAS1        \n\
 286                 str     %7, [%1, #12]           @ MDCAS2        \n\
 287                 str     %8, [%2, #0]            @ PPCR          \n\
 288                 ldr     %0, [%1, #0]                            \n\
 289                 b       3f                                      \n\
 290 2:              b       1b                                      \n\
 291 3:              nop                                             \n\
 292                 nop"
 293                 : "=&r" (unused)
 294                 : "r" (&MDCNFG), "r" (&PPCR), "0" (sd.mdcnfg),
 295                   "r" (sd.mdrefr), "r" (sd.mdcas[0]),
 296                   "r" (sd.mdcas[1]), "r" (sd.mdcas[2]), "r" (ppcr));
 297         local_irq_restore(flags);
 298
 299         /*
 300          * Now, return the SDRAM refresh back to normal.
 301          */
 302         sdram_update_refresh(sa11x0_freq_table[ppcr].frequency, sdram);
 303
 304         return 0;
 305 }
 306
 307 static int __init sa1110_cpu_init(struct cpufreq_policy *policy)
 308 {
 309         return cpufreq_generic_init(policy, sa11x0_freq_table, CPUFREQ_ETERNAL);
 310 }
 311
 312 /* sa1110_driver needs __refdata because it must remain after init registers
 313  * it with cpufreq_register_driver() */
 314 static struct cpufreq_driver sa1110_driver __refdata = {
 315         .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 316         .verify         = cpufreq_generic_frequency_table_verify,
 317         .target_index   = sa1110_target,
 318         .get            = sa11x0_getspeed,
 319         .init           = sa1110_cpu_init,
 320         .name           = "sa1110",
 321 };
 322
 323 static struct sdram_params *sa1110_find_sdram(const char *name)
 324 {
 325         struct sdram_params *sdram;
 326
 327         for (sdram = sdram_tbl; sdram < sdram_tbl + ARRAY_SIZE(sdram_tbl);
 328              sdram++)
 329                 if (strcmp(name, sdram->name) == 0)
 330                         return sdram;
 331
 332         return NULL;
 333 }
 334
 335 static char sdram_name[16];
 336
 337 static int __init sa1110_clk_init(void)
 338 {
 339         struct sdram_params *sdram;
 340         const char *name = sdram_name;
 341
 342         if (!cpu_is_sa1110())
 343                 return -ENODEV;
 344
 345         if (!name[0]) {
 346                 if (machine_is_assabet())
 347                         name = "TC59SM716-CL3";
 348                 if (machine_is_pt_system3())
 349                         name = "K4S641632D";
 350                 if (machine_is_h3100())
 351                         name = "KM416S4030CT";
 352                 if (machine_is_jornada720() || machine_is_h3600())
 353                         name = "K4S281632B-1H";
 354                 if (machine_is_nanoengine())
 355                         name = "MT48LC8M16A2TG-75";
 356         }
 357
 358         sdram = sa1110_find_sdram(name);
 359         if (sdram) {
 360                 printk(KERN_DEBUG "SDRAM: tck: %d trcd: %d trp: %d"
 361                         " twr: %d refresh: %d cas_latency: %d\n",
 362                         sdram->tck, sdram->trcd, sdram->trp,
 363                         sdram->twr, sdram->refresh, sdram->cas_latency);
 364
 365                 memcpy(&sdram_params, sdram, sizeof(sdram_params));
 366
 367                 return cpufreq_register_driver(&sa1110_driver);
 368         }
 369
 370         return 0;
 371 }
 372
 373 module_param_string(sdram, sdram_name, sizeof(sdram_name), 0);
 374 arch_initcall(sa1110_clk_init);