cpu/mpc8xx/speed.c

   1 /*
   2  * (C) Copyright 2000-2004
   3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 #include <common.h>
  25 #include <mpc8xx.h>
  26 #include <asm/processor.h>
  27
  28 DECLARE_GLOBAL_DATA_PTR;
  29
  30 #if !defined(CONFIG_8xx_CPUCLK_DEFAULT) || defined(CONFIG_SYS_MEASURE_CPUCLK) || defined(DEBUG)
  31
  32 #define PITC_SHIFT 16
  33 #define PITR_SHIFT 16
  34 /* pitc values to time for 58/8192 seconds (about 70.8 milliseconds) */
  35 #define SPEED_PIT_COUNTS 58
  36 #define SPEED_PITC       ((SPEED_PIT_COUNTS - 1) << PITC_SHIFT)
  37 #define SPEED_PITC_INIT  ((SPEED_PIT_COUNTS + 1) << PITC_SHIFT)
  38
  39 /* Access functions for the Machine State Register */
  40 static __inline__ unsigned long get_msr(void)
  41 {
  42         unsigned long msr;
  43
  44         asm volatile("mfmsr %0" : "=r" (msr) :);
  45         return msr;
  46 }
  47
  48 static __inline__ void set_msr(unsigned long msr)
  49 {
  50         asm volatile("mtmsr %0" : : "r" (msr));
  51 }
  52
  53 /* ------------------------------------------------------------------------- */
  54
  55 /*
  56  * Measure CPU clock speed (core clock GCLK1, GCLK2),
  57  * also determine bus clock speed (checking bus divider factor)
  58  *
  59  * (Approx. GCLK frequency in Hz)
  60  *
  61  * Initializes timer 2 and PIT, but disables them before return.
  62  * [Use timer 2, because MPC823 CPUs mask 0.x do not have timers 3 and 4]
  63  *
  64  * When measuring the CPU clock against the PIT, we count cpu clocks
  65  * for 58/8192 seconds with a prescale divide by 177 for the cpu clock.
  66  * These strange values for the timing interval and prescaling are used
  67  * because the formula for the CPU clock is:
  68  *
  69  *    CPU clock = count * (177 * (8192 / 58))
  70  *
  71  *              = count * 24999.7241
  72  *
  73  *    which is very close to
  74  *
  75  *              = count * 25000
  76  *
  77  * Since the count gives the CPU clock divided by 25000, we can get
  78  * the CPU clock rounded to the nearest 0.1 MHz by
  79  *
  80  *    CPU clock = ((count + 2) / 4) * 100000;
  81  *
  82  * The rounding is important since the measurement is sometimes going
  83  * to be high or low by 0.025 MHz, depending on exactly how the clocks
  84  * and counters interact. By rounding we get the exact answer for any
  85  * CPU clock that is an even multiple of 0.1 MHz.
  86  */
  87
  88 unsigned long measure_gclk(void)
  89 {
  90         volatile immap_t *immr = (immap_t *) CONFIG_SYS_IMMR;
  91         volatile cpmtimer8xx_t *timerp = &immr->im_cpmtimer;
  92         ulong timer2_val;
  93         ulong msr_val;
  94
  95 #ifdef CONFIG_SYS_8XX_XIN
  96         /* dont use OSCM, only use EXTCLK/512 */
  97         immr->im_clkrst.car_sccr |= SCCR_RTSEL | SCCR_RTDIV;
  98 #else
  99         immr->im_clkrst.car_sccr &= ~(SCCR_RTSEL | SCCR_RTDIV);
 100 #endif
 101
 102         /* Reset + Stop Timer 2, no cascading
 103          */
 104         timerp->cpmt_tgcr &= ~(TGCR_CAS2 | TGCR_RST2);
 105
 106         /* Keep stopped, halt in debug mode
 107          */
 108         timerp->cpmt_tgcr |= (TGCR_FRZ2 | TGCR_STP2);
 109
 110         /* Timer 2 setup:
 111          * Output ref. interrupt disable, int. clock
 112          * Prescale by 177. Note that prescaler divides by value + 1
 113          * so we must subtract 1 here.
 114          */
 115         timerp->cpmt_tmr2 = ((177 - 1) << TMR_PS_SHIFT) | TMR_ICLK_IN_GEN;
 116
 117         timerp->cpmt_tcn2 = 0;          /* reset state          */
 118         timerp->cpmt_tgcr |= TGCR_RST2; /* enable timer 2       */
 119
 120         /*
 121          * PIT setup:
 122          *
 123          * We want to time for SPEED_PITC_COUNTS counts (of 8192 Hz),
 124          * so the count value would be SPEED_PITC_COUNTS - 1.
 125          * But there would be an uncertainty in the start time of 1/4
 126          * count since when we enable the PIT the count is not
 127          * synchronized to the 32768 Hz oscillator. The trick here is
 128          * to start the count higher and wait until the PIT count
 129          * changes to the required value before starting timer 2.
 130          *
 131          * One count high should be enough, but occasionally the start
 132          * is off by 1 or 2 counts of 32768 Hz. With the start value
 133          * set two counts high it seems very reliable.
 134          */
 135
 136         immr->im_sitk.sitk_pitck = KAPWR_KEY;   /* PIT initialization */
 137         immr->im_sit.sit_pitc = SPEED_PITC_INIT;
 138
 139         immr->im_sitk.sitk_piscrk = KAPWR_KEY;
 140         immr->im_sit.sit_piscr = CONFIG_SYS_PISCR;
 141
 142         /*
 143          * Start measurement - disable interrupts, just in case
 144          */
 145         msr_val = get_msr ();
 146         set_msr (msr_val & ~MSR_EE);
 147
 148         immr->im_sit.sit_piscr |= PISCR_PTE;
 149
 150         /* spin until get exact count when we want to start */
 151         while (immr->im_sit.sit_pitr > SPEED_PITC);
 152
 153         timerp->cpmt_tgcr &= ~TGCR_STP2;        /* Start Timer 2        */
 154         while ((immr->im_sit.sit_piscr & PISCR_PS) == 0);
 155         timerp->cpmt_tgcr |= TGCR_STP2;         /* Stop  Timer 2        */
 156
 157         /* re-enable external interrupts if they were on */
 158         set_msr (msr_val);
 159
 160         /* Disable timer and PIT
 161          */
 162         timer2_val = timerp->cpmt_tcn2;         /* save before reset timer */
 163
 164         timerp->cpmt_tgcr &= ~(TGCR_RST2 | TGCR_FRZ2 | TGCR_STP2);
 165         immr->im_sit.sit_piscr &= ~PISCR_PTE;
 166
 167 #if defined(CONFIG_SYS_8XX_XIN)
 168         /* not using OSCM, using XIN, so scale appropriately */
 169         return (((timer2_val + 2) / 4) * (CONFIG_SYS_8XX_XIN/512))/8192 * 100000L;
 170 #else
 171         return ((timer2_val + 2) / 4) * 100000L;        /* convert to Hz        */
 172 #endif
 173 }
 174
 175 #endif
 176
 177 void get_brgclk(uint sccr)
 178 {
 179         uint divider = 0;
 180
 181         switch((sccr&SCCR_DFBRG11)>>11){
 182                 case 0:
 183                         divider = 1;
 184                         break;
 185                 case 1:
 186                         divider = 4;
 187                         break;
 188                 case 2:
 189                         divider = 16;
 190                         break;
 191                 case 3:
 192                         divider = 64;
 193                         break;
 194         }
 195         gd->brg_clk = gd->cpu_clk/divider;
 196 }
 197
 198 #if !defined(CONFIG_8xx_CPUCLK_DEFAULT)
 199
 200 /*
 201  * get_clocks() fills in gd->cpu_clock depending on CONFIG_8xx_GCLK_FREQ
 202  * or (if it is not defined) measure_gclk() (which uses the ref clock)
 203  * from above.
 204  */
 205 int get_clocks (void)
 206 {
 207         uint immr = get_immr (0);       /* Return full IMMR contents */
 208         volatile immap_t *immap = (immap_t *) (immr & 0xFFFF0000);
 209         uint sccr = immap->im_clkrst.car_sccr;
 210         /*
 211          * If for some reason measuring the gclk frequency won't
 212          * work, we return the hardwired value.
 213          * (For example, the cogent CMA286-60 CPU module has no
 214          * separate oscillator for PITRTCLK)
 215          */
 216 #if defined(CONFIG_8xx_GCLK_FREQ)
 217         gd->cpu_clk = CONFIG_8xx_GCLK_FREQ;
 218 #elif defined(CONFIG_8xx_OSCLK)
 219 #define PLPRCR_val(a) ((pll & PLPRCR_ ## a ## _MSK) >> PLPRCR_ ## a ## _SHIFT)
 220         uint pll = immap->im_clkrst.car_plprcr;
 221         uint clk;
 222
 223         if ((immr & 0x0FFF) >= MPC8xx_NEW_CLK) { /* MPC866/87x/88x series */
 224                 clk = ((CONFIG_8xx_OSCLK / (PLPRCR_val(PDF)+1)) *
 225                        (PLPRCR_val(MFI) + PLPRCR_val(MFN) / (PLPRCR_val(MFD)+1))) /
 226                         (1<<PLPRCR_val(S));
 227         } else {
 228                 clk = CONFIG_8xx_OSCLK * (PLPRCR_val(MF)+1);
 229         }
 230         if (pll & PLPRCR_CSRC) {        /* Low frequency division factor is used  */
 231                 gd->cpu_clk = clk / (2 << ((sccr >> 8) & 7));
 232         } else {                        /* High frequency division factor is used */
 233                 gd->cpu_clk = clk / (1 << ((sccr >> 5) & 7));
 234         }
 235 #else
 236         gd->cpu_clk = measure_gclk();
 237 #endif /* CONFIG_8xx_GCLK_FREQ */
 238
 239         if ((sccr & SCCR_EBDF11) == 0) {
 240                 /* No Bus Divider active */
 241                 gd->bus_clk = gd->cpu_clk;
 242         } else {
 243                 /* The MPC8xx has only one BDF: half clock speed */
 244                 gd->bus_clk = gd->cpu_clk / 2;
 245         }
 246
 247         get_brgclk(sccr);
 248
 249         return (0);
 250 }
 251
 252 #else /* CONFIG_8xx_CPUCLK_DEFAULT defined, use dynamic clock setting */
 253
 254 static long init_pll_866 (long clk);
 255
 256 /* This function sets up PLL (init_pll_866() is called) and
 257  * fills gd->cpu_clk and gd->bus_clk according to the environment
 258  * variable 'cpuclk' or to CONFIG_8xx_CPUCLK_DEFAULT (if 'cpuclk'
 259  * contains invalid value).
 260  * This functions requires an MPC866 or newer series CPU.
 261  */
 262 int get_clocks_866 (void)
 263 {
 264         volatile immap_t *immr = (immap_t *) CONFIG_SYS_IMMR;
 265         char              tmp[64];
 266         long              cpuclk = 0;
 267         long              sccr_reg;
 268
 269         if (getenv_r ("cpuclk", tmp, sizeof (tmp)) > 0)
 270                 cpuclk = simple_strtoul (tmp, NULL, 10) * 1000000;
 271
 272         if ((CONFIG_SYS_8xx_CPUCLK_MIN > cpuclk) || (CONFIG_SYS_8xx_CPUCLK_MAX < cpuclk))
 273                 cpuclk = CONFIG_8xx_CPUCLK_DEFAULT;
 274
 275         gd->cpu_clk = init_pll_866 (cpuclk);
 276 #if defined(CONFIG_SYS_MEASURE_CPUCLK)
 277         gd->cpu_clk = measure_gclk ();
 278 #endif
 279
 280         get_brgclk(immr->im_clkrst.car_sccr);
 281
 282         /* if cpu clock <= 66 MHz then set bus division factor to 1,
 283          * otherwise set it to 2
 284          */
 285         sccr_reg = immr->im_clkrst.car_sccr;
 286         sccr_reg &= ~SCCR_EBDF11;
 287
 288         if (gd->cpu_clk <= 66000000) {
 289                 sccr_reg |= SCCR_EBDF00;        /* bus division factor = 1 */
 290                 gd->bus_clk = gd->cpu_clk;
 291         } else {
 292                 sccr_reg |= SCCR_EBDF01;        /* bus division factor = 2 */
 293                 gd->bus_clk = gd->cpu_clk / 2;
 294         }
 295         immr->im_clkrst.car_sccr = sccr_reg;
 296
 297         return (0);
 298 }
 299
 300 /* Adjust sdram refresh rate to actual CPU clock.
 301  */
 302 int sdram_adjust_866 (void)
 303 {
 304         volatile immap_t *immr = (immap_t *) CONFIG_SYS_IMMR;
 305         long              mamr;
 306
 307         mamr = immr->im_memctl.memc_mamr;
 308         mamr &= ~MAMR_PTA_MSK;
 309         mamr |= ((gd->cpu_clk / CONFIG_SYS_PTA_PER_CLK) << MAMR_PTA_SHIFT);
 310         immr->im_memctl.memc_mamr = mamr;
 311
 312         return (0);
 313 }
 314
 315 /* Configure PLL for MPC866/859/885 CPU series
 316  * PLL multiplication factor is set to the value nearest to the desired clk,
 317  * assuming a oscclk of 10 MHz.
 318  */
 319 static long init_pll_866 (long clk)
 320 {
 321         extern void plprcr_write_866 (long);
 322
 323         volatile immap_t *immr = (immap_t *) CONFIG_SYS_IMMR;
 324         long              n, plprcr;
 325         char              mfi, mfn, mfd, s, pdf;
 326         long              step_mfi, step_mfn;
 327
 328         if (clk < 20000000) {
 329                 clk *= 2;
 330                 pdf = 1;
 331         } else {
 332                 pdf = 0;
 333         }
 334
 335         if (clk < 40000000) {
 336                 s = 2;
 337                 step_mfi = CONFIG_8xx_OSCLK / 4;
 338                 mfd = 7;
 339                 step_mfn = CONFIG_8xx_OSCLK / 30;
 340         } else if (clk < 80000000) {
 341                 s = 1;
 342                 step_mfi = CONFIG_8xx_OSCLK / 2;
 343                 mfd = 14;
 344                 step_mfn = CONFIG_8xx_OSCLK / 30;
 345         } else {
 346                 s = 0;
 347                 step_mfi = CONFIG_8xx_OSCLK;
 348                 mfd = 29;
 349                 step_mfn = CONFIG_8xx_OSCLK / 30;
 350         }
 351
 352         /* Calculate integer part of multiplication factor
 353          */
 354         n = clk / step_mfi;
 355         mfi = (char)n;
 356
 357         /* Calculate numerator of fractional part of multiplication factor
 358          */
 359         n = clk - (n * step_mfi);
 360         mfn = (char)(n / step_mfn);
 361
 362         /* Calculate effective clk
 363          */
 364         n = ((mfi * step_mfi) + (mfn * step_mfn)) / (pdf + 1);
 365
 366         immr->im_clkrstk.cark_plprcrk = KAPWR_KEY;
 367
 368         plprcr = (immr->im_clkrst.car_plprcr & ~(PLPRCR_MFN_MSK
 369                         | PLPRCR_MFD_MSK | PLPRCR_S_MSK
 370                         | PLPRCR_MFI_MSK | PLPRCR_DBRMO
 371                         | PLPRCR_PDF_MSK))
 372                         | (mfn << PLPRCR_MFN_SHIFT)
 373                         | (mfd << PLPRCR_MFD_SHIFT)
 374                         | (s << PLPRCR_S_SHIFT)
 375                         | (mfi << PLPRCR_MFI_SHIFT)
 376                         | (pdf << PLPRCR_PDF_SHIFT);
 377
 378         if( (mfn > 0) && ((mfd / mfn) > 10) )
 379                 plprcr |= PLPRCR_DBRMO;
 380
 381         plprcr_write_866 (plprcr);              /* set value using SIU4/9 workaround */
 382         immr->im_clkrstk.cark_plprcrk = 0x00000000;
 383
 384         return (n);
 385 }
 386
 387 #endif /* CONFIG_8xx_CPUCLK_DEFAULT */
 388
 389 #if defined(CONFIG_TQM8xxL) && !defined(CONFIG_TQM866M) \
 390     && !defined(CONFIG_TQM885D)
 391 /*
 392  * Adjust sdram refresh rate to actual CPU clock
 393  * and set timebase source according to actual CPU clock
 394  */
 395 int adjust_sdram_tbs_8xx (void)
 396 {
 397         volatile immap_t *immr = (immap_t *) CONFIG_SYS_IMMR;
 398         long              mamr;
 399         long              sccr;
 400
 401         mamr = immr->im_memctl.memc_mamr;
 402         mamr &= ~MAMR_PTA_MSK;
 403         mamr |= ((gd->cpu_clk / CONFIG_SYS_PTA_PER_CLK) << MAMR_PTA_SHIFT);
 404         immr->im_memctl.memc_mamr = mamr;
 405
 406         if (gd->cpu_clk < 67000000) {
 407                 sccr = immr->im_clkrst.car_sccr;
 408                 sccr |= SCCR_TBS;
 409                 immr->im_clkrst.car_sccr = sccr;
 410         }
 411
 412         return (0);
 413 }
 414 #endif /* CONFIG_TQM8xxL/M, !TQM866M, !TQM885D */
 415
 416 /* ------------------------------------------------------------------------- */