1 /* 2 * Copyright 2008 Freescale Semiconductor, Inc. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * Version 2 as published by the Free Software Foundation. 7 */ 8 9 #include <common.h> 10 #include <fsl_ddr_sdram.h> 11 12 #include <fsl_ddr.h> 13 /* 14 * Calculate the Density of each Physical Rank. 15 * Returned size is in bytes. 16 * 17 * Study these table from Byte 31 of JEDEC SPD Spec. 18 * 19 * DDR I DDR II 20 * Bit Size Size 21 * --- ----- ------ 22 * 7 high 512MB 512MB 23 * 6 256MB 256MB 24 * 5 128MB 128MB 25 * 4 64MB 16GB 26 * 3 32MB 8GB 27 * 2 16MB 4GB 28 * 1 2GB 2GB 29 * 0 low 1GB 1GB 30 * 31 * Reorder Table to be linear by stripping the bottom 32 * 2 or 5 bits off and shifting them up to the top. 33 * 34 */ 35 static unsigned long long 36 compute_ranksize(unsigned int mem_type, unsigned char row_dens) 37 { 38 unsigned long long bsize; 39 40 /* Bottom 5 bits up to the top. */ 41 bsize = ((row_dens >> 5) | ((row_dens & 31) << 3)); 42 bsize <<= 27ULL; 43 debug("DDR: DDR II rank density = 0x%16llx\n", bsize); 44 45 return bsize; 46 } 47 48 /* 49 * Convert a two-nibble BCD value into a cycle time. 50 * While the spec calls for nano-seconds, picos are returned. 51 * 52 * This implements the tables for bytes 9, 23 and 25 for both 53 * DDR I and II. No allowance for distinguishing the invalid 54 * fields absent for DDR I yet present in DDR II is made. 55 * (That is, cycle times of .25, .33, .66 and .75 ns are 56 * allowed for both DDR II and I.) 57 */ 58 static unsigned int 59 convert_bcd_tenths_to_cycle_time_ps(unsigned int spd_val) 60 { 61 /* Table look up the lower nibble, allow DDR I & II. */ 62 unsigned int tenths_ps[16] = { 63 0, 64 100, 65 200, 66 300, 67 400, 68 500, 69 600, 70 700, 71 800, 72 900, 73 250, /* This and the next 3 entries valid ... */ 74 330, /* ... only for tCK calculations. */ 75 660, 76 750, 77 0, /* undefined */ 78 0 /* undefined */ 79 }; 80 81 unsigned int whole_ns = (spd_val & 0xF0) >> 4; 82 unsigned int tenth_ns = spd_val & 0x0F; 83 unsigned int ps = whole_ns * 1000 + tenths_ps[tenth_ns]; 84 85 return ps; 86 } 87 88 static unsigned int 89 convert_bcd_hundredths_to_cycle_time_ps(unsigned int spd_val) 90 { 91 unsigned int tenth_ns = (spd_val & 0xF0) >> 4; 92 unsigned int hundredth_ns = spd_val & 0x0F; 93 unsigned int ps = tenth_ns * 100 + hundredth_ns * 10; 94 95 return ps; 96 } 97 98 static unsigned int byte40_table_ps[8] = { 99 0, 100 250, 101 330, 102 500, 103 660, 104 750, 105 0, /* supposed to be RFC, but not sure what that means */ 106 0 /* Undefined */ 107 }; 108 109 static unsigned int 110 compute_trfc_ps_from_spd(unsigned char trctrfc_ext, unsigned char trfc) 111 { 112 unsigned int trfc_ps; 113 114 trfc_ps = (((trctrfc_ext & 0x1) * 256) + trfc) * 1000 115 + byte40_table_ps[(trctrfc_ext >> 1) & 0x7]; 116 117 return trfc_ps; 118 } 119 120 static unsigned int 121 compute_trc_ps_from_spd(unsigned char trctrfc_ext, unsigned char trc) 122 { 123 unsigned int trc_ps; 124 125 trc_ps = trc * 1000 + byte40_table_ps[(trctrfc_ext >> 4) & 0x7]; 126 127 return trc_ps; 128 } 129 130 /* 131 * Determine Refresh Rate. Ignore self refresh bit on DDR I. 132 * Table from SPD Spec, Byte 12, converted to picoseconds and 133 * filled in with "default" normal values. 134 */ 135 static unsigned int 136 determine_refresh_rate_ps(const unsigned int spd_refresh) 137 { 138 unsigned int refresh_time_ps[8] = { 139 15625000, /* 0 Normal 1.00x */ 140 3900000, /* 1 Reduced .25x */ 141 7800000, /* 2 Extended .50x */ 142 31300000, /* 3 Extended 2.00x */ 143 62500000, /* 4 Extended 4.00x */ 144 125000000, /* 5 Extended 8.00x */ 145 15625000, /* 6 Normal 1.00x filler */ 146 15625000, /* 7 Normal 1.00x filler */ 147 }; 148 149 return refresh_time_ps[spd_refresh & 0x7]; 150 } 151 152 /* 153 * The purpose of this function is to compute a suitable 154 * CAS latency given the DRAM clock period. The SPD only 155 * defines at most 3 CAS latencies. Typically the slower in 156 * frequency the DIMM runs at, the shorter its CAS latency can. 157 * be. If the DIMM is operating at a sufficiently low frequency, 158 * it may be able to run at a CAS latency shorter than the 159 * shortest SPD-defined CAS latency. 160 * 161 * If a CAS latency is not found, 0 is returned. 162 * 163 * Do this by finding in the standard speed bin table the longest 164 * tCKmin that doesn't exceed the value of mclk_ps (tCK). 165 * 166 * An assumption made is that the SDRAM device allows the 167 * CL to be programmed for a value that is lower than those 168 * advertised by the SPD. This is not always the case, 169 * as those modes not defined in the SPD are optional. 170 * 171 * CAS latency de-rating based upon values JEDEC Standard No. 79-2C 172 * Table 40, "DDR2 SDRAM stanadard speed bins and tCK, tRCD, tRP, tRAS, 173 * and tRC for corresponding bin" 174 * 175 * ordinal 2, ddr2_speed_bins[1] contains tCK for CL=3 176 * Not certain if any good value exists for CL=2 177 */ 178 /* CL2 CL3 CL4 CL5 CL6 CL7*/ 179 unsigned short ddr2_speed_bins[] = { 0, 5000, 3750, 3000, 2500, 1875 }; 180 181 unsigned int 182 compute_derated_DDR2_CAS_latency(unsigned int mclk_ps) 183 { 184 const unsigned int num_speed_bins = ARRAY_SIZE(ddr2_speed_bins); 185 unsigned int lowest_tCKmin_found = 0; 186 unsigned int lowest_tCKmin_CL = 0; 187 unsigned int i; 188 189 debug("mclk_ps = %u\n", mclk_ps); 190 191 for (i = 0; i < num_speed_bins; i++) { 192 unsigned int x = ddr2_speed_bins[i]; 193 debug("i=%u, x = %u, lowest_tCKmin_found = %u\n", 194 i, x, lowest_tCKmin_found); 195 if (x && x <= mclk_ps && x >= lowest_tCKmin_found ) { 196 lowest_tCKmin_found = x; 197 lowest_tCKmin_CL = i + 2; 198 } 199 } 200 201 debug("lowest_tCKmin_CL = %u\n", lowest_tCKmin_CL); 202 203 return lowest_tCKmin_CL; 204 } 205 206 /* 207 * ddr_compute_dimm_parameters for DDR2 SPD 208 * 209 * Compute DIMM parameters based upon the SPD information in spd. 210 * Writes the results to the dimm_params_t structure pointed by pdimm. 211 * 212 * FIXME: use #define for the retvals 213 */ 214 unsigned int 215 ddr_compute_dimm_parameters(const ddr2_spd_eeprom_t *spd, 216 dimm_params_t *pdimm, 217 unsigned int dimm_number) 218 { 219 unsigned int retval; 220 221 if (spd->mem_type) { 222 if (spd->mem_type != SPD_MEMTYPE_DDR2) { 223 printf("DIMM %u: is not a DDR2 SPD.\n", dimm_number); 224 return 1; 225 } 226 } else { 227 memset(pdimm, 0, sizeof(dimm_params_t)); 228 return 1; 229 } 230 231 retval = ddr2_spd_check(spd); 232 if (retval) { 233 printf("DIMM %u: failed checksum\n", dimm_number); 234 return 2; 235 } 236 237 /* 238 * The part name in ASCII in the SPD EEPROM is not null terminated. 239 * Guarantee null termination here by presetting all bytes to 0 240 * and copying the part name in ASCII from the SPD onto it 241 */ 242 memset(pdimm->mpart, 0, sizeof(pdimm->mpart)); 243 memcpy(pdimm->mpart, spd->mpart, sizeof(pdimm->mpart) - 1); 244 245 /* DIMM organization parameters */ 246 pdimm->n_ranks = (spd->mod_ranks & 0x7) + 1; 247 pdimm->rank_density = compute_ranksize(spd->mem_type, spd->rank_dens); 248 pdimm->capacity = pdimm->n_ranks * pdimm->rank_density; 249 pdimm->data_width = spd->dataw; 250 pdimm->primary_sdram_width = spd->primw; 251 pdimm->ec_sdram_width = spd->ecw; 252 253 /* These are all the types defined by the JEDEC DDR2 SPD 1.3 spec */ 254 switch (spd->dimm_type) { 255 case DDR2_SPD_DIMMTYPE_RDIMM: 256 case DDR2_SPD_DIMMTYPE_72B_SO_RDIMM: 257 case DDR2_SPD_DIMMTYPE_MINI_RDIMM: 258 /* Registered/buffered DIMMs */ 259 pdimm->registered_dimm = 1; 260 break; 261 262 case DDR2_SPD_DIMMTYPE_UDIMM: 263 case DDR2_SPD_DIMMTYPE_SO_DIMM: 264 case DDR2_SPD_DIMMTYPE_MICRO_DIMM: 265 case DDR2_SPD_DIMMTYPE_MINI_UDIMM: 266 /* Unbuffered DIMMs */ 267 pdimm->registered_dimm = 0; 268 break; 269 270 case DDR2_SPD_DIMMTYPE_72B_SO_CDIMM: 271 default: 272 printf("unknown dimm_type 0x%02X\n", spd->dimm_type); 273 return 1; 274 } 275 276 /* SDRAM device parameters */ 277 pdimm->n_row_addr = spd->nrow_addr; 278 pdimm->n_col_addr = spd->ncol_addr; 279 pdimm->n_banks_per_sdram_device = spd->nbanks; 280 pdimm->edc_config = spd->config; 281 pdimm->burst_lengths_bitmask = spd->burstl; 282 pdimm->row_density = spd->rank_dens; 283 284 /* 285 * Calculate the Maximum Data Rate based on the Minimum Cycle time. 286 * The SPD clk_cycle field (tCKmin) is measured in tenths of 287 * nanoseconds and represented as BCD. 288 */ 289 pdimm->tckmin_x_ps 290 = convert_bcd_tenths_to_cycle_time_ps(spd->clk_cycle); 291 pdimm->tckmin_x_minus_1_ps 292 = convert_bcd_tenths_to_cycle_time_ps(spd->clk_cycle2); 293 pdimm->tckmin_x_minus_2_ps 294 = convert_bcd_tenths_to_cycle_time_ps(spd->clk_cycle3); 295 296 pdimm->tckmax_ps = convert_bcd_tenths_to_cycle_time_ps(spd->tckmax); 297 298 /* 299 * Compute CAS latencies defined by SPD 300 * The SPD caslat_x should have at least 1 and at most 3 bits set. 301 * 302 * If cas_lat after masking is 0, the __ilog2 function returns 303 * 255 into the variable. This behavior is abused once. 304 */ 305 pdimm->caslat_x = __ilog2(spd->cas_lat); 306 pdimm->caslat_x_minus_1 = __ilog2(spd->cas_lat 307 & ~(1 << pdimm->caslat_x)); 308 pdimm->caslat_x_minus_2 = __ilog2(spd->cas_lat 309 & ~(1 << pdimm->caslat_x) 310 & ~(1 << pdimm->caslat_x_minus_1)); 311 312 /* Compute CAS latencies below that defined by SPD */ 313 pdimm->caslat_lowest_derated 314 = compute_derated_DDR2_CAS_latency(get_memory_clk_period_ps()); 315 316 /* Compute timing parameters */ 317 pdimm->trcd_ps = spd->trcd * 250; 318 pdimm->trp_ps = spd->trp * 250; 319 pdimm->tras_ps = spd->tras * 1000; 320 321 pdimm->twr_ps = spd->twr * 250; 322 pdimm->twtr_ps = spd->twtr * 250; 323 pdimm->trfc_ps = compute_trfc_ps_from_spd(spd->trctrfc_ext, spd->trfc); 324 325 pdimm->trrd_ps = spd->trrd * 250; 326 pdimm->trc_ps = compute_trc_ps_from_spd(spd->trctrfc_ext, spd->trc); 327 328 pdimm->refresh_rate_ps = determine_refresh_rate_ps(spd->refresh); 329 330 pdimm->tis_ps = convert_bcd_hundredths_to_cycle_time_ps(spd->ca_setup); 331 pdimm->tih_ps = convert_bcd_hundredths_to_cycle_time_ps(spd->ca_hold); 332 pdimm->tds_ps 333 = convert_bcd_hundredths_to_cycle_time_ps(spd->data_setup); 334 pdimm->tdh_ps 335 = convert_bcd_hundredths_to_cycle_time_ps(spd->data_hold); 336 337 pdimm->trtp_ps = spd->trtp * 250; 338 pdimm->tdqsq_max_ps = spd->tdqsq * 10; 339 pdimm->tqhs_ps = spd->tqhs * 10; 340 341 return 0; 342 } 343