drivers/cpufreq/sa1110-cpufreq.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/arch/arm/mach-sa1100/cpu-sa1110.c
   4  *
   5  *  Copyright (C) 2001 Russell King
   6  *
   7  * Note: there are two erratas that apply to the SA1110 here:
   8  *  7 - SDRAM auto-power-up failure (rev A0)
   9  * 13 - Corruption of internal register reads/writes following
  10  *      SDRAM reads (rev A0, B0, B1)
  11  *
  12  * We ignore rev. A0 and B0 devices; I don't think they're worth supporting.
  13  *
  14  * The SDRAM type can be passed on the command line as cpu_sa1110.sdram=type
  15  */
  16 #include <linux/cpufreq.h>
  17 #include <linux/delay.h>
  18 #include <linux/init.h>
  19 #include <linux/io.h>
  20 #include <linux/kernel.h>
  21 #include <linux/moduleparam.h>
  22 #include <linux/types.h>
  23
  24 #include <asm/cputype.h>
  25 #include <asm/mach-types.h>
  26
  27 #include <mach/generic.h>
  28 #include <mach/hardware.h>
  29
  30 #undef DEBUG
  31
  32 struct sdram_params {
  33         const char name[20];
  34         u_char  rows;           /* bits                          */
  35         u_char  cas_latency;    /* cycles                        */
  36         u_char  tck;            /* clock cycle time (ns)         */
  37         u_char  trcd;           /* activate to r/w (ns)          */
  38         u_char  trp;            /* precharge to activate (ns)    */
  39         u_char  twr;            /* write recovery time (ns)      */
  40         u_short refresh;        /* refresh time for array (us)   */
  41 };
  42
  43 struct sdram_info {
  44         u_int   mdcnfg;
  45         u_int   mdrefr;
  46         u_int   mdcas[3];
  47 };
  48
  49 static struct sdram_params sdram_tbl[] __initdata = {
  50         {       /* Toshiba TC59SM716 CL2 */
  51                 .name           = "TC59SM716-CL2",
  52                 .rows           = 12,
  53                 .tck            = 10,
  54                 .trcd           = 20,
  55                 .trp            = 20,
  56                 .twr            = 10,
  57                 .refresh        = 64000,
  58                 .cas_latency    = 2,
  59         }, {    /* Toshiba TC59SM716 CL3 */
  60                 .name           = "TC59SM716-CL3",
  61                 .rows           = 12,
  62                 .tck            = 8,
  63                 .trcd           = 20,
  64                 .trp            = 20,
  65                 .twr            = 8,
  66                 .refresh        = 64000,
  67                 .cas_latency    = 3,
  68         }, {    /* Samsung K4S641632D TC75 */
  69                 .name           = "K4S641632D",
  70                 .rows           = 14,
  71                 .tck            = 9,
  72                 .trcd           = 27,
  73                 .trp            = 20,
  74                 .twr            = 9,
  75                 .refresh        = 64000,
  76                 .cas_latency    = 3,
  77         }, {    /* Samsung K4S281632B-1H */
  78                 .name           = "K4S281632B-1H",
  79                 .rows           = 12,
  80                 .tck            = 10,
  81                 .trp            = 20,
  82                 .twr            = 10,
  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         }, {    /* Micron MT48LC8M16A2TG-75 */
 104                 .name           = "MT48LC8M16A2TG-75",
 105                 .rows           = 12,
 106                 .tck            = 8,
 107                 .trcd           = 20,
 108                 .trp            = 20,
 109                 .twr            = 8,
 110                 .refresh        = 64000,
 111                 .cas_latency    = 3,
 112         },
 113 };
 114
 115 static struct sdram_params sdram_params;
 116
 117 /*
 118  * Given a period in ns and frequency in khz, calculate the number of
 119  * cycles of frequency in period.  Note that we round up to the next
 120  * cycle, even if we are only slightly over.
 121  */
 122 static inline u_int ns_to_cycles(u_int ns, u_int khz)
 123 {
 124         return (ns * khz + 999999) / 1000000;
 125 }
 126
 127 /*
 128  * Create the MDCAS register bit pattern.
 129  */
 130 static inline void set_mdcas(u_int *mdcas, int delayed, u_int rcd)
 131 {
 132         u_int shift;
 133
 134         rcd = 2 * rcd - 1;
 135         shift = delayed + 1 + rcd;
 136
 137         mdcas[0]  = (1 << rcd) - 1;
 138         mdcas[0] |= 0x55555555 << shift;
 139         mdcas[1]  = mdcas[2] = 0x55555555 << (shift & 1);
 140 }
 141
 142 static void
 143 sdram_calculate_timing(struct sdram_info *sd, u_int cpu_khz,
 144                        struct sdram_params *sdram)
 145 {
 146         u_int mem_khz, sd_khz, trp, twr;
 147
 148         mem_khz = cpu_khz / 2;
 149         sd_khz = mem_khz;
 150
 151         /*
 152          * If SDCLK would invalidate the SDRAM timings,
 153          * run SDCLK at half speed.
 154          *
 155          * CPU steppings prior to B2 must either run the memory at
 156          * half speed or use delayed read latching (errata 13).
 157          */
 158         if ((ns_to_cycles(sdram->tck, sd_khz) > 1) ||
 159             (read_cpuid_revision() < ARM_CPU_REV_SA1110_B2 && sd_khz < 62000))
 160                 sd_khz /= 2;
 161
 162         sd->mdcnfg = MDCNFG & 0x007f007f;
 163
 164         twr = ns_to_cycles(sdram->twr, mem_khz);
 165
 166         /* trp should always be >1 */
 167         trp = ns_to_cycles(sdram->trp, mem_khz) - 1;
 168         if (trp < 1)
 169                 trp = 1;
 170
 171         sd->mdcnfg |= trp << 8;
 172         sd->mdcnfg |= trp << 24;
 173         sd->mdcnfg |= sdram->cas_latency << 12;
 174         sd->mdcnfg |= sdram->cas_latency << 28;
 175         sd->mdcnfg |= twr << 14;
 176         sd->mdcnfg |= twr << 30;
 177
 178         sd->mdrefr = MDREFR & 0xffbffff0;
 179         sd->mdrefr |= 7;
 180
 181         if (sd_khz != mem_khz)
 182                 sd->mdrefr |= MDREFR_K1DB2;
 183
 184         /* initial number of '1's in MDCAS + 1 */
 185         set_mdcas(sd->mdcas, sd_khz >= 62000,
 186                 ns_to_cycles(sdram->trcd, mem_khz));
 187
 188 #ifdef DEBUG
 189         printk(KERN_DEBUG "MDCNFG: %08x MDREFR: %08x MDCAS0: %08x MDCAS1: %08x MDCAS2: %08x\n",
 190                 sd->mdcnfg, sd->mdrefr, sd->mdcas[0], sd->mdcas[1],
 191                 sd->mdcas[2]);
 192 #endif
 193 }
 194
 195 /*
 196  * Set the SDRAM refresh rate.
 197  */
 198 static inline void sdram_set_refresh(u_int dri)
 199 {
 200         MDREFR = (MDREFR & 0xffff000f) | (dri << 4);
 201         (void) MDREFR;
 202 }
 203
 204 /*
 205  * Update the refresh period.  We do this such that we always refresh
 206  * the SDRAMs within their permissible period.  The refresh period is
 207  * always a multiple of the memory clock (fixed at cpu_clock / 2).
 208  *
 209  * FIXME: we don't currently take account of burst accesses here,
 210  * but neither do Intels DM nor Angel.
 211  */
 212 static void
 213 sdram_update_refresh(u_int cpu_khz, struct sdram_params *sdram)
 214 {
 215         u_int ns_row = (sdram->refresh * 1000) >> sdram->rows;
 216         u_int dri = ns_to_cycles(ns_row, cpu_khz / 2) / 32;
 217
 218 #ifdef DEBUG
 219         mdelay(250);
 220         printk(KERN_DEBUG "new dri value = %d\n", dri);
 221 #endif
 222
 223         sdram_set_refresh(dri);
 224 }
 225
 226 /*
 227  * Ok, set the CPU frequency.
 228  */
 229 static int sa1110_target(struct cpufreq_policy *policy, unsigned int ppcr)
 230 {
 231         struct sdram_params *sdram = &sdram_params;
 232         struct sdram_info sd;
 233         unsigned long flags;
 234         unsigned int unused;
 235
 236         sdram_calculate_timing(&sd, sa11x0_freq_table[ppcr].frequency, sdram);
 237
 238 #if 0
 239         /*
 240          * These values are wrong according to the SA1110 documentation
 241          * and errata, but they seem to work.  Need to get a storage
 242          * scope on to the SDRAM signals to work out why.
 243          */
 244         if (policy->max < 147500) {
 245                 sd.mdrefr |= MDREFR_K1DB2;
 246                 sd.mdcas[0] = 0xaaaaaa7f;
 247         } else {
 248                 sd.mdrefr &= ~MDREFR_K1DB2;
 249                 sd.mdcas[0] = 0xaaaaaa9f;
 250         }
 251         sd.mdcas[1] = 0xaaaaaaaa;
 252         sd.mdcas[2] = 0xaaaaaaaa;
 253 #endif
 254
 255         /*
 256          * The clock could be going away for some time.  Set the SDRAMs
 257          * to refresh rapidly (every 64 memory clock cycles).  To get
 258          * through the whole array, we need to wait 262144 mclk cycles.
 259          * We wait 20ms to be safe.
 260          */
 261         sdram_set_refresh(2);
 262         if (!irqs_disabled())
 263                 msleep(20);
 264         else
 265                 mdelay(20);
 266
 267         /*
 268          * Reprogram the DRAM timings with interrupts disabled, and
 269          * ensure that we are doing this within a complete cache line.
 270          * This means that we won't access SDRAM for the duration of
 271          * the programming.
 272          */
 273         local_irq_save(flags);
 274         asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (0));
 275         udelay(10);
 276         __asm__ __volatile__("\n\
 277                 b       2f                                      \n\
 278                 .align  5                                       \n\
 279 1:              str     %3, [%1, #0]            @ MDCNFG        \n\
 280                 str     %4, [%1, #28]           @ MDREFR        \n\
 281                 str     %5, [%1, #4]            @ MDCAS0        \n\
 282                 str     %6, [%1, #8]            @ MDCAS1        \n\
 283                 str     %7, [%1, #12]           @ MDCAS2        \n\
 284                 str     %8, [%2, #0]            @ PPCR          \n\
 285                 ldr     %0, [%1, #0]                            \n\
 286                 b       3f                                      \n\
 287 2:              b       1b                                      \n\
 288 3:              nop                                             \n\
 289                 nop"
 290                 : "=&r" (unused)
 291                 : "r" (&MDCNFG), "r" (&PPCR), "0" (sd.mdcnfg),
 292                   "r" (sd.mdrefr), "r" (sd.mdcas[0]),
 293                   "r" (sd.mdcas[1]), "r" (sd.mdcas[2]), "r" (ppcr));
 294         local_irq_restore(flags);
 295
 296         /*
 297          * Now, return the SDRAM refresh back to normal.
 298          */
 299         sdram_update_refresh(sa11x0_freq_table[ppcr].frequency, sdram);
 300
 301         return 0;
 302 }
 303
 304 static int __init sa1110_cpu_init(struct cpufreq_policy *policy)
 305 {
 306         cpufreq_generic_init(policy, sa11x0_freq_table, 0);
 307         return 0;
 308 }
 309
 310 /* sa1110_driver needs __refdata because it must remain after init registers
 311  * it with cpufreq_register_driver() */
 312 static struct cpufreq_driver sa1110_driver __refdata = {
 313         .flags          = CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 314                           CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
 315         .verify         = cpufreq_generic_frequency_table_verify,
 316         .target_index   = sa1110_target,
 317         .get            = sa11x0_getspeed,
 318         .init           = sa1110_cpu_init,
 319         .name           = "sa1110",
 320 };
 321
 322 static struct sdram_params *sa1110_find_sdram(const char *name)
 323 {
 324         struct sdram_params *sdram;
 325
 326         for (sdram = sdram_tbl; sdram < sdram_tbl + ARRAY_SIZE(sdram_tbl);
 327              sdram++)
 328                 if (strcmp(name, sdram->name) == 0)
 329                         return sdram;
 330
 331         return NULL;
 332 }
 333
 334 static char sdram_name[16];
 335
 336 static int __init sa1110_clk_init(void)
 337 {
 338         struct sdram_params *sdram;
 339         const char *name = sdram_name;
 340
 341         if (!cpu_is_sa1110())
 342                 return -ENODEV;
 343
 344         if (!name[0]) {
 345                 if (machine_is_assabet())
 346                         name = "TC59SM716-CL3";
 347                 if (machine_is_jornada720() || machine_is_h3600())
 348                         name = "K4S281632B-1H";
 349         }
 350
 351         sdram = sa1110_find_sdram(name);
 352         if (sdram) {
 353                 printk(KERN_DEBUG "SDRAM: tck: %d trcd: %d trp: %d"
 354                         " twr: %d refresh: %d cas_latency: %d\n",
 355                         sdram->tck, sdram->trcd, sdram->trp,
 356                         sdram->twr, sdram->refresh, sdram->cas_latency);
 357
 358                 memcpy(&sdram_params, sdram, sizeof(sdram_params));
 359
 360                 return cpufreq_register_driver(&sa1110_driver);
 361         }
 362
 363         return 0;
 364 }
 365
 366 module_param_string(sdram, sdram_name, sizeof(sdram_name), 0);
 367 arch_initcall(sa1110_clk_init);