arch/powerpc/cpu/mpc85xx/speed.c

   1 /*
   2  * Copyright 2004, 2007-2011 Freescale Semiconductor, Inc.
   3  *
   4  * (C) Copyright 2003 Motorola Inc.
   5  * Xianghua Xiao, (X.Xiao@motorola.com)
   6  *
   7  * (C) Copyright 2000
   8  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   9  *
  10  * SPDX-License-Identifier:     GPL-2.0+
  11  */
  12
  13 #include <common.h>
  14 #include <ppc_asm.tmpl>
  15 #include <linux/compiler.h>
  16 #include <asm/processor.h>
  17 #include <asm/io.h>
  18
  19 DECLARE_GLOBAL_DATA_PTR;
  20
  21
  22 #ifndef CONFIG_SYS_FSL_NUM_CC_PLLS
  23 #define CONFIG_SYS_FSL_NUM_CC_PLLS      6
  24 #endif
  25 /* --------------------------------------------------------------- */
  26
  27 void get_sys_info(sys_info_t *sys_info)
  28 {
  29         volatile ccsr_gur_t *gur = (void *)(CONFIG_SYS_MPC85xx_GUTS_ADDR);
  30 #ifdef CONFIG_FSL_IFC
  31         struct fsl_ifc *ifc_regs = (void *)CONFIG_SYS_IFC_ADDR;
  32         u32 ccr;
  33 #endif
  34 #ifdef CONFIG_FSL_CORENET
  35         volatile ccsr_clk_t *clk = (void *)(CONFIG_SYS_FSL_CORENET_CLK_ADDR);
  36         unsigned int cpu;
  37 #ifdef CONFIG_SYS_FSL_QORIQ_CHASSIS2
  38         int cc_group[12] = CONFIG_SYS_FSL_CLUSTER_CLOCKS;
  39 #endif
  40
  41         const u8 core_cplx_PLL[16] = {
  42                 [ 0] = 0,       /* CC1 PPL / 1 */
  43                 [ 1] = 0,       /* CC1 PPL / 2 */
  44                 [ 2] = 0,       /* CC1 PPL / 4 */
  45                 [ 4] = 1,       /* CC2 PPL / 1 */
  46                 [ 5] = 1,       /* CC2 PPL / 2 */
  47                 [ 6] = 1,       /* CC2 PPL / 4 */
  48                 [ 8] = 2,       /* CC3 PPL / 1 */
  49                 [ 9] = 2,       /* CC3 PPL / 2 */
  50                 [10] = 2,       /* CC3 PPL / 4 */
  51                 [12] = 3,       /* CC4 PPL / 1 */
  52                 [13] = 3,       /* CC4 PPL / 2 */
  53                 [14] = 3,       /* CC4 PPL / 4 */
  54         };
  55
  56         const u8 core_cplx_pll_div[16] = {
  57                 [ 0] = 1,       /* CC1 PPL / 1 */
  58                 [ 1] = 2,       /* CC1 PPL / 2 */
  59                 [ 2] = 4,       /* CC1 PPL / 4 */
  60                 [ 4] = 1,       /* CC2 PPL / 1 */
  61                 [ 5] = 2,       /* CC2 PPL / 2 */
  62                 [ 6] = 4,       /* CC2 PPL / 4 */
  63                 [ 8] = 1,       /* CC3 PPL / 1 */
  64                 [ 9] = 2,       /* CC3 PPL / 2 */
  65                 [10] = 4,       /* CC3 PPL / 4 */
  66                 [12] = 1,       /* CC4 PPL / 1 */
  67                 [13] = 2,       /* CC4 PPL / 2 */
  68                 [14] = 4,       /* CC4 PPL / 4 */
  69         };
  70         uint i, freq_c_pll[CONFIG_SYS_FSL_NUM_CC_PLLS];
  71 #if !defined(CONFIG_FM_PLAT_CLK_DIV) || !defined(CONFIG_PME_PLAT_CLK_DIV)
  72         uint rcw_tmp;
  73 #endif
  74         uint ratio[CONFIG_SYS_FSL_NUM_CC_PLLS];
  75         unsigned long sysclk = CONFIG_SYS_CLK_FREQ;
  76         uint mem_pll_rat;
  77
  78         sys_info->freq_systembus = sysclk;
  79 #ifdef CONFIG_DDR_CLK_FREQ
  80         sys_info->freq_ddrbus = CONFIG_DDR_CLK_FREQ;
  81 #else
  82         sys_info->freq_ddrbus = sysclk;
  83 #endif
  84
  85         sys_info->freq_systembus *= (in_be32(&gur->rcwsr[0]) >> 25) & 0x1f;
  86         mem_pll_rat = (in_be32(&gur->rcwsr[0]) >>
  87                         FSL_CORENET_RCWSR0_MEM_PLL_RAT_SHIFT)
  88                         & FSL_CORENET_RCWSR0_MEM_PLL_RAT_MASK;
  89         /* T4240/T4160 Rev2.0 MEM_PLL_RAT uses a value which is half of
  90          * T4240/T4160 Rev1.0. eg. It's 12 in Rev1.0, however, for Rev2.0
  91          * it uses 6.
  92          */
  93 #if defined(CONFIG_PPC_T4240) || defined(CONFIG_PPC_T4160)
  94         if (SVR_MAJ(get_svr()) >= 2)
  95                 mem_pll_rat *= 2;
  96 #endif
  97         if (mem_pll_rat > 2)
  98                 sys_info->freq_ddrbus *= mem_pll_rat;
  99         else
 100                 sys_info->freq_ddrbus = sys_info->freq_systembus * mem_pll_rat;
 101
 102         for (i = 0; i < CONFIG_SYS_FSL_NUM_CC_PLLS; i++) {
 103                 ratio[i] = (in_be32(&clk->pllcgsr[i].pllcngsr) >> 1) & 0x3f;
 104                 if (ratio[i] > 4)
 105                         freq_c_pll[i] = sysclk * ratio[i];
 106                 else
 107                         freq_c_pll[i] = sys_info->freq_systembus * ratio[i];
 108         }
 109 #ifdef CONFIG_SYS_FSL_QORIQ_CHASSIS2
 110         /*
 111          * As per CHASSIS2 architeture total 12 clusters are posible and
 112          * Each cluster has up to 4 cores, sharing the same PLL selection.
 113          * The cluster clock assignment is SoC defined.
 114          *
 115          * Total 4 clock groups are possible with 3 PLLs each.
 116          * as per array indices, clock group A has 0, 1, 2 numbered PLLs &
 117          * clock group B has 3, 4, 6 and so on.
 118          *
 119          * Clock group A having PLL1, PLL2, PLL3, feeding cores of any cluster
 120          * depends upon the SoC architeture. Same applies to other
 121          * clock groups and clusters.
 122          *
 123          */
 124         for_each_cpu(i, cpu, cpu_numcores(), cpu_mask()) {
 125                 int cluster = fsl_qoriq_core_to_cluster(cpu);
 126                 u32 c_pll_sel = (in_be32(&clk->clkcsr[cluster].clkcncsr) >> 27)
 127                                 & 0xf;
 128                 u32 cplx_pll = core_cplx_PLL[c_pll_sel];
 129                 cplx_pll += cc_group[cluster] - 1;
 130                 sys_info->freq_processor[cpu] =
 131                          freq_c_pll[cplx_pll] / core_cplx_pll_div[c_pll_sel];
 132         }
 133 #if defined(CONFIG_PPC_B4860) || defined(CONFIG_PPC_T2080)
 134 #define FM1_CLK_SEL     0xe0000000
 135 #define FM1_CLK_SHIFT   29
 136 #else
 137 #define PME_CLK_SEL     0xe0000000
 138 #define PME_CLK_SHIFT   29
 139 #define FM1_CLK_SEL     0x1c000000
 140 #define FM1_CLK_SHIFT   26
 141 #endif
 142 #if !defined(CONFIG_FM_PLAT_CLK_DIV) || !defined(CONFIG_PME_PLAT_CLK_DIV)
 143         rcw_tmp = in_be32(&gur->rcwsr[7]);
 144 #endif
 145
 146 #ifdef CONFIG_SYS_DPAA_PME
 147 #ifndef CONFIG_PME_PLAT_CLK_DIV
 148         switch ((rcw_tmp & PME_CLK_SEL) >> PME_CLK_SHIFT) {
 149         case 1:
 150                 sys_info->freq_pme = freq_c_pll[CONFIG_SYS_PME_CLK];
 151                 break;
 152         case 2:
 153                 sys_info->freq_pme = freq_c_pll[CONFIG_SYS_PME_CLK] / 2;
 154                 break;
 155         case 3:
 156                 sys_info->freq_pme = freq_c_pll[CONFIG_SYS_PME_CLK] / 3;
 157                 break;
 158         case 4:
 159                 sys_info->freq_pme = freq_c_pll[CONFIG_SYS_PME_CLK] / 4;
 160                 break;
 161         case 6:
 162                 sys_info->freq_pme = freq_c_pll[CONFIG_SYS_PME_CLK + 1] / 2;
 163                 break;
 164         case 7:
 165                 sys_info->freq_pme = freq_c_pll[CONFIG_SYS_PME_CLK + 1] / 3;
 166                 break;
 167         default:
 168                 printf("Error: Unknown PME clock select!\n");
 169         case 0:
 170                 sys_info->freq_pme = sys_info->freq_systembus / 2;
 171                 break;
 172
 173         }
 174 #else
 175         sys_info->freq_pme = sys_info->freq_systembus / CONFIG_SYS_PME_CLK;
 176
 177 #endif
 178 #endif
 179
 180 #ifdef CONFIG_SYS_DPAA_QBMAN
 181         sys_info->freq_qman = sys_info->freq_systembus / 2;
 182 #endif
 183
 184 #ifdef CONFIG_SYS_DPAA_FMAN
 185 #ifndef CONFIG_FM_PLAT_CLK_DIV
 186         switch ((rcw_tmp & FM1_CLK_SEL) >> FM1_CLK_SHIFT) {
 187         case 1:
 188                 sys_info->freq_fman[0] = freq_c_pll[CONFIG_SYS_FM1_CLK];
 189                 break;
 190         case 2:
 191                 sys_info->freq_fman[0] = freq_c_pll[CONFIG_SYS_FM1_CLK] / 2;
 192                 break;
 193         case 3:
 194                 sys_info->freq_fman[0] = freq_c_pll[CONFIG_SYS_FM1_CLK] / 3;
 195                 break;
 196         case 4:
 197                 sys_info->freq_fman[0] = freq_c_pll[CONFIG_SYS_FM1_CLK] / 4;
 198                 break;
 199         case 5:
 200                 sys_info->freq_fman[0] = sys_info->freq_systembus;
 201                 break;
 202         case 6:
 203                 sys_info->freq_fman[0] = freq_c_pll[CONFIG_SYS_FM1_CLK + 1] / 2;
 204                 break;
 205         case 7:
 206                 sys_info->freq_fman[0] = freq_c_pll[CONFIG_SYS_FM1_CLK + 1] / 3;
 207                 break;
 208         default:
 209                 printf("Error: Unknown FMan1 clock select!\n");
 210         case 0:
 211                 sys_info->freq_fman[0] = sys_info->freq_systembus / 2;
 212                 break;
 213         }
 214 #if (CONFIG_SYS_NUM_FMAN) == 2
 215 #ifdef CONFIG_SYS_FM2_CLK
 216 #define FM2_CLK_SEL     0x00000038
 217 #define FM2_CLK_SHIFT   3
 218         rcw_tmp = in_be32(&gur->rcwsr[15]);
 219         switch ((rcw_tmp & FM2_CLK_SEL) >> FM2_CLK_SHIFT) {
 220         case 1:
 221                 sys_info->freq_fman[1] = freq_c_pll[CONFIG_SYS_FM2_CLK + 1];
 222                 break;
 223         case 2:
 224                 sys_info->freq_fman[1] = freq_c_pll[CONFIG_SYS_FM2_CLK + 1] / 2;
 225                 break;
 226         case 3:
 227                 sys_info->freq_fman[1] = freq_c_pll[CONFIG_SYS_FM2_CLK + 1] / 3;
 228                 break;
 229         case 4:
 230                 sys_info->freq_fman[1] = freq_c_pll[CONFIG_SYS_FM2_CLK + 1] / 4;
 231                 break;
 232         case 5:
 233                 sys_info->freq_fman[1] = sys_info->freq_systembus;
 234                 break;
 235         case 6:
 236                 sys_info->freq_fman[1] = freq_c_pll[CONFIG_SYS_FM2_CLK] / 2;
 237                 break;
 238         case 7:
 239                 sys_info->freq_fman[1] = freq_c_pll[CONFIG_SYS_FM2_CLK] / 3;
 240                 break;
 241         default:
 242                 printf("Error: Unknown FMan2 clock select!\n");
 243         case 0:
 244                 sys_info->freq_fman[1] = sys_info->freq_systembus / 2;
 245                 break;
 246         }
 247 #endif
 248 #endif  /* CONFIG_SYS_NUM_FMAN == 2 */
 249 #else
 250         sys_info->freq_fman[0] = sys_info->freq_systembus / CONFIG_SYS_FM1_CLK;
 251 #endif
 252 #endif
 253
 254 #else /* CONFIG_SYS_FSL_QORIQ_CHASSIS2 */
 255
 256         for_each_cpu(i, cpu, cpu_numcores(), cpu_mask()) {
 257                 u32 c_pll_sel = (in_be32(&clk->clkcsr[cpu].clkcncsr) >> 27)
 258                                 & 0xf;
 259                 u32 cplx_pll = core_cplx_PLL[c_pll_sel];
 260
 261                 sys_info->freq_processor[cpu] =
 262                          freq_c_pll[cplx_pll] / core_cplx_pll_div[c_pll_sel];
 263         }
 264 #define PME_CLK_SEL     0x80000000
 265 #define FM1_CLK_SEL     0x40000000
 266 #define FM2_CLK_SEL     0x20000000
 267 #define HWA_ASYNC_DIV   0x04000000
 268 #if (CONFIG_SYS_FSL_NUM_CC_PLLS == 2)
 269 #define HWA_CC_PLL      1
 270 #elif (CONFIG_SYS_FSL_NUM_CC_PLLS == 3)
 271 #define HWA_CC_PLL      2
 272 #elif (CONFIG_SYS_FSL_NUM_CC_PLLS == 4)
 273 #define HWA_CC_PLL      2
 274 #else
 275 #error CONFIG_SYS_FSL_NUM_CC_PLLS not set or unknown case
 276 #endif
 277         rcw_tmp = in_be32(&gur->rcwsr[7]);
 278
 279 #ifdef CONFIG_SYS_DPAA_PME
 280         if (rcw_tmp & PME_CLK_SEL) {
 281                 if (rcw_tmp & HWA_ASYNC_DIV)
 282                         sys_info->freq_pme = freq_c_pll[HWA_CC_PLL] / 4;
 283                 else
 284                         sys_info->freq_pme = freq_c_pll[HWA_CC_PLL] / 2;
 285         } else {
 286                 sys_info->freq_pme = sys_info->freq_systembus / 2;
 287         }
 288 #endif
 289
 290 #ifdef CONFIG_SYS_DPAA_FMAN
 291         if (rcw_tmp & FM1_CLK_SEL) {
 292                 if (rcw_tmp & HWA_ASYNC_DIV)
 293                         sys_info->freq_fman[0] = freq_c_pll[HWA_CC_PLL] / 4;
 294                 else
 295                         sys_info->freq_fman[0] = freq_c_pll[HWA_CC_PLL] / 2;
 296         } else {
 297                 sys_info->freq_fman[0] = sys_info->freq_systembus / 2;
 298         }
 299 #if (CONFIG_SYS_NUM_FMAN) == 2
 300         if (rcw_tmp & FM2_CLK_SEL) {
 301                 if (rcw_tmp & HWA_ASYNC_DIV)
 302                         sys_info->freq_fman[1] = freq_c_pll[HWA_CC_PLL] / 4;
 303                 else
 304                         sys_info->freq_fman[1] = freq_c_pll[HWA_CC_PLL] / 2;
 305         } else {
 306                 sys_info->freq_fman[1] = sys_info->freq_systembus / 2;
 307         }
 308 #endif
 309 #endif
 310
 311 #ifdef CONFIG_SYS_DPAA_QBMAN
 312         sys_info->freq_qman = sys_info->freq_systembus / 2;
 313 #endif
 314
 315 #endif /* CONFIG_SYS_FSL_QORIQ_CHASSIS2 */
 316
 317 #else /* CONFIG_FSL_CORENET */
 318         uint plat_ratio, e500_ratio, half_freq_systembus;
 319         int i;
 320 #ifdef CONFIG_QE
 321         __maybe_unused u32 qe_ratio;
 322 #endif
 323
 324         plat_ratio = (gur->porpllsr) & 0x0000003e;
 325         plat_ratio >>= 1;
 326         sys_info->freq_systembus = plat_ratio * CONFIG_SYS_CLK_FREQ;
 327
 328         /* Divide before multiply to avoid integer
 329          * overflow for processor speeds above 2GHz */
 330         half_freq_systembus = sys_info->freq_systembus/2;
 331         for (i = 0; i < cpu_numcores(); i++) {
 332                 e500_ratio = ((gur->porpllsr) >> (i * 8 + 16)) & 0x3f;
 333                 sys_info->freq_processor[i] = e500_ratio * half_freq_systembus;
 334         }
 335
 336         /* Note: freq_ddrbus is the MCLK frequency, not the data rate. */
 337         sys_info->freq_ddrbus = sys_info->freq_systembus;
 338
 339 #ifdef CONFIG_DDR_CLK_FREQ
 340         {
 341                 u32 ddr_ratio = ((gur->porpllsr) & MPC85xx_PORPLLSR_DDR_RATIO)
 342                         >> MPC85xx_PORPLLSR_DDR_RATIO_SHIFT;
 343                 if (ddr_ratio != 0x7)
 344                         sys_info->freq_ddrbus = ddr_ratio * CONFIG_DDR_CLK_FREQ;
 345         }
 346 #endif
 347
 348 #ifdef CONFIG_QE
 349 #if defined(CONFIG_P1012) || defined(CONFIG_P1021) || defined(CONFIG_P1025)
 350         sys_info->freq_qe =  sys_info->freq_systembus;
 351 #else
 352         qe_ratio = ((gur->porpllsr) & MPC85xx_PORPLLSR_QE_RATIO)
 353                         >> MPC85xx_PORPLLSR_QE_RATIO_SHIFT;
 354         sys_info->freq_qe = qe_ratio * CONFIG_SYS_CLK_FREQ;
 355 #endif
 356 #endif
 357
 358 #ifdef CONFIG_SYS_DPAA_FMAN
 359                 sys_info->freq_fman[0] = sys_info->freq_systembus;
 360 #endif
 361
 362 #endif /* CONFIG_FSL_CORENET */
 363
 364 #if defined(CONFIG_FSL_LBC)
 365         uint lcrr_div;
 366 #if defined(CONFIG_SYS_LBC_LCRR)
 367         /* We will program LCRR to this value later */
 368         lcrr_div = CONFIG_SYS_LBC_LCRR & LCRR_CLKDIV;
 369 #else
 370         lcrr_div = in_be32(&(LBC_BASE_ADDR)->lcrr) & LCRR_CLKDIV;
 371 #endif
 372         if (lcrr_div == 2 || lcrr_div == 4 || lcrr_div == 8) {
 373 #if defined(CONFIG_FSL_CORENET)
 374                 /* If this is corenet based SoC, bit-representation
 375                  * for four times the clock divider values.
 376                  */
 377                 lcrr_div *= 4;
 378 #elif !defined(CONFIG_MPC8540) && !defined(CONFIG_MPC8541) && \
 379     !defined(CONFIG_MPC8555) && !defined(CONFIG_MPC8560)
 380                 /*
 381                  * Yes, the entire PQ38 family use the same
 382                  * bit-representation for twice the clock divider values.
 383                  */
 384                 lcrr_div *= 2;
 385 #endif
 386                 sys_info->freq_localbus = sys_info->freq_systembus / lcrr_div;
 387         } else {
 388                 /* In case anyone cares what the unknown value is */
 389                 sys_info->freq_localbus = lcrr_div;
 390         }
 391 #endif
 392
 393 #if defined(CONFIG_FSL_IFC)
 394         ccr = in_be32(&ifc_regs->ifc_ccr);
 395         ccr = ((ccr & IFC_CCR_CLK_DIV_MASK) >> IFC_CCR_CLK_DIV_SHIFT) + 1;
 396
 397         sys_info->freq_localbus = sys_info->freq_systembus / ccr;
 398 #endif
 399 }
 400
 401
 402 int get_clocks (void)
 403 {
 404         sys_info_t sys_info;
 405 #ifdef CONFIG_MPC8544
 406         volatile ccsr_gur_t *gur = (void *) CONFIG_SYS_MPC85xx_GUTS_ADDR;
 407 #endif
 408 #if defined(CONFIG_CPM2)
 409         volatile ccsr_cpm_t *cpm = (ccsr_cpm_t *)CONFIG_SYS_MPC85xx_CPM_ADDR;
 410         uint sccr, dfbrg;
 411
 412         /* set VCO = 4 * BRG */
 413         cpm->im_cpm_intctl.sccr &= 0xfffffffc;
 414         sccr = cpm->im_cpm_intctl.sccr;
 415         dfbrg = (sccr & SCCR_DFBRG_MSK) >> SCCR_DFBRG_SHIFT;
 416 #endif
 417         get_sys_info (&sys_info);
 418         gd->cpu_clk = sys_info.freq_processor[0];
 419         gd->bus_clk = sys_info.freq_systembus;
 420         gd->mem_clk = sys_info.freq_ddrbus;
 421         gd->arch.lbc_clk = sys_info.freq_localbus;
 422
 423 #ifdef CONFIG_QE
 424         gd->arch.qe_clk = sys_info.freq_qe;
 425         gd->arch.brg_clk = gd->arch.qe_clk / 2;
 426 #endif
 427         /*
 428          * The base clock for I2C depends on the actual SOC.  Unfortunately,
 429          * there is no pattern that can be used to determine the frequency, so
 430          * the only choice is to look up the actual SOC number and use the value
 431          * for that SOC. This information is taken from application note
 432          * AN2919.
 433          */
 434 #if defined(CONFIG_MPC8540) || defined(CONFIG_MPC8541) || \
 435         defined(CONFIG_MPC8560) || defined(CONFIG_MPC8555) || \
 436         defined(CONFIG_P1022)
 437         gd->arch.i2c1_clk = sys_info.freq_systembus;
 438 #elif defined(CONFIG_MPC8544)
 439         /*
 440          * On the 8544, the I2C clock is the same as the SEC clock.  This can be
 441          * either CCB/2 or CCB/3, depending on the value of cfg_sec_freq. See
 442          * 4.4.3.3 of the 8544 RM.  Note that this might actually work for all
 443          * 85xx, but only the 8544 has cfg_sec_freq, so it's unknown if the
 444          * PORDEVSR2_SEC_CFG bit is 0 on all 85xx boards that are not an 8544.
 445          */
 446         if (gur->pordevsr2 & MPC85xx_PORDEVSR2_SEC_CFG)
 447                 gd->arch.i2c1_clk = sys_info.freq_systembus / 3;
 448         else
 449                 gd->arch.i2c1_clk = sys_info.freq_systembus / 2;
 450 #else
 451         /* Most 85xx SOCs use CCB/2, so this is the default behavior. */
 452         gd->arch.i2c1_clk = sys_info.freq_systembus / 2;
 453 #endif
 454         gd->arch.i2c2_clk = gd->arch.i2c1_clk;
 455
 456 #if defined(CONFIG_FSL_ESDHC)
 457 #if defined(CONFIG_MPC8569) || defined(CONFIG_P1010) ||\
 458        defined(CONFIG_P1014)
 459         gd->arch.sdhc_clk = gd->bus_clk;
 460 #else
 461         gd->arch.sdhc_clk = gd->bus_clk / 2;
 462 #endif
 463 #endif /* defined(CONFIG_FSL_ESDHC) */
 464
 465 #if defined(CONFIG_CPM2)
 466         gd->arch.vco_out = 2*sys_info.freq_systembus;
 467         gd->arch.cpm_clk = gd->arch.vco_out / 2;
 468         gd->arch.scc_clk = gd->arch.vco_out / 4;
 469         gd->arch.brg_clk = gd->arch.vco_out / (1 << (2 * (dfbrg + 1)));
 470 #endif
 471
 472         if(gd->cpu_clk != 0) return (0);
 473         else return (1);
 474 }
 475
 476
 477 /********************************************
 478  * get_bus_freq
 479  * return system bus freq in Hz
 480  *********************************************/
 481 ulong get_bus_freq (ulong dummy)
 482 {
 483         return gd->bus_clk;
 484 }
 485
 486 /********************************************
 487  * get_ddr_freq
 488  * return ddr bus freq in Hz
 489  *********************************************/
 490 ulong get_ddr_freq (ulong dummy)
 491 {
 492         return gd->mem_clk;
 493 }