1 /* 2 * Copyright 2008 Freescale Semiconductor, Inc. 3 * 4 * SPDX-License-Identifier: GPL-2.0 5 */ 6 7 #include <common.h> 8 #include <fsl_ddr_sdram.h> 9 10 #include <fsl_ddr.h> 11 /* 12 * Calculate the Density of each Physical Rank. 13 * Returned size is in bytes. 14 * 15 * Study these table from Byte 31 of JEDEC SPD Spec. 16 * 17 * DDR I DDR II 18 * Bit Size Size 19 * --- ----- ------ 20 * 7 high 512MB 512MB 21 * 6 256MB 256MB 22 * 5 128MB 128MB 23 * 4 64MB 16GB 24 * 3 32MB 8GB 25 * 2 16MB 4GB 26 * 1 2GB 2GB 27 * 0 low 1GB 1GB 28 * 29 * Reorder Table to be linear by stripping the bottom 30 * 2 or 5 bits off and shifting them up to the top. 31 * 32 */ 33 static unsigned long long 34 compute_ranksize(unsigned int mem_type, unsigned char row_dens) 35 { 36 unsigned long long bsize; 37 38 /* Bottom 5 bits up to the top. */ 39 bsize = ((row_dens >> 5) | ((row_dens & 31) << 3)); 40 bsize <<= 27ULL; 41 debug("DDR: DDR II rank density = 0x%16llx\n", bsize); 42 43 return bsize; 44 } 45 46 /* 47 * Convert a two-nibble BCD value into a cycle time. 48 * While the spec calls for nano-seconds, picos are returned. 49 * 50 * This implements the tables for bytes 9, 23 and 25 for both 51 * DDR I and II. No allowance for distinguishing the invalid 52 * fields absent for DDR I yet present in DDR II is made. 53 * (That is, cycle times of .25, .33, .66 and .75 ns are 54 * allowed for both DDR II and I.) 55 */ 56 static unsigned int 57 convert_bcd_tenths_to_cycle_time_ps(unsigned int spd_val) 58 { 59 /* Table look up the lower nibble, allow DDR I & II. */ 60 unsigned int tenths_ps[16] = { 61 0, 62 100, 63 200, 64 300, 65 400, 66 500, 67 600, 68 700, 69 800, 70 900, 71 250, /* This and the next 3 entries valid ... */ 72 330, /* ... only for tCK calculations. */ 73 660, 74 750, 75 0, /* undefined */ 76 0 /* undefined */ 77 }; 78 79 unsigned int whole_ns = (spd_val & 0xF0) >> 4; 80 unsigned int tenth_ns = spd_val & 0x0F; 81 unsigned int ps = whole_ns * 1000 + tenths_ps[tenth_ns]; 82 83 return ps; 84 } 85 86 static unsigned int 87 convert_bcd_hundredths_to_cycle_time_ps(unsigned int spd_val) 88 { 89 unsigned int tenth_ns = (spd_val & 0xF0) >> 4; 90 unsigned int hundredth_ns = spd_val & 0x0F; 91 unsigned int ps = tenth_ns * 100 + hundredth_ns * 10; 92 93 return ps; 94 } 95 96 static unsigned int byte40_table_ps[8] = { 97 0, 98 250, 99 330, 100 500, 101 660, 102 750, 103 0, /* supposed to be RFC, but not sure what that means */ 104 0 /* Undefined */ 105 }; 106 107 static unsigned int 108 compute_trfc_ps_from_spd(unsigned char trctrfc_ext, unsigned char trfc) 109 { 110 return (((trctrfc_ext & 0x1) * 256) + trfc) * 1000 111 + byte40_table_ps[(trctrfc_ext >> 1) & 0x7]; 112 } 113 114 static unsigned int 115 compute_trc_ps_from_spd(unsigned char trctrfc_ext, unsigned char trc) 116 { 117 return trc * 1000 + byte40_table_ps[(trctrfc_ext >> 4) & 0x7]; 118 } 119 120 /* 121 * Determine Refresh Rate. Ignore self refresh bit on DDR I. 122 * Table from SPD Spec, Byte 12, converted to picoseconds and 123 * filled in with "default" normal values. 124 */ 125 static unsigned int 126 determine_refresh_rate_ps(const unsigned int spd_refresh) 127 { 128 unsigned int refresh_time_ps[8] = { 129 15625000, /* 0 Normal 1.00x */ 130 3900000, /* 1 Reduced .25x */ 131 7800000, /* 2 Extended .50x */ 132 31300000, /* 3 Extended 2.00x */ 133 62500000, /* 4 Extended 4.00x */ 134 125000000, /* 5 Extended 8.00x */ 135 15625000, /* 6 Normal 1.00x filler */ 136 15625000, /* 7 Normal 1.00x filler */ 137 }; 138 139 return refresh_time_ps[spd_refresh & 0x7]; 140 } 141 142 /* 143 * The purpose of this function is to compute a suitable 144 * CAS latency given the DRAM clock period. The SPD only 145 * defines at most 3 CAS latencies. Typically the slower in 146 * frequency the DIMM runs at, the shorter its CAS latency can. 147 * be. If the DIMM is operating at a sufficiently low frequency, 148 * it may be able to run at a CAS latency shorter than the 149 * shortest SPD-defined CAS latency. 150 * 151 * If a CAS latency is not found, 0 is returned. 152 * 153 * Do this by finding in the standard speed bin table the longest 154 * tCKmin that doesn't exceed the value of mclk_ps (tCK). 155 * 156 * An assumption made is that the SDRAM device allows the 157 * CL to be programmed for a value that is lower than those 158 * advertised by the SPD. This is not always the case, 159 * as those modes not defined in the SPD are optional. 160 * 161 * CAS latency de-rating based upon values JEDEC Standard No. 79-2C 162 * Table 40, "DDR2 SDRAM stanadard speed bins and tCK, tRCD, tRP, tRAS, 163 * and tRC for corresponding bin" 164 * 165 * ordinal 2, ddr2_speed_bins[1] contains tCK for CL=3 166 * Not certain if any good value exists for CL=2 167 */ 168 /* CL2 CL3 CL4 CL5 CL6 CL7*/ 169 unsigned short ddr2_speed_bins[] = { 0, 5000, 3750, 3000, 2500, 1875 }; 170 171 unsigned int 172 compute_derated_DDR2_CAS_latency(unsigned int mclk_ps) 173 { 174 const unsigned int num_speed_bins = ARRAY_SIZE(ddr2_speed_bins); 175 unsigned int lowest_tCKmin_found = 0; 176 unsigned int lowest_tCKmin_CL = 0; 177 unsigned int i; 178 179 debug("mclk_ps = %u\n", mclk_ps); 180 181 for (i = 0; i < num_speed_bins; i++) { 182 unsigned int x = ddr2_speed_bins[i]; 183 debug("i=%u, x = %u, lowest_tCKmin_found = %u\n", 184 i, x, lowest_tCKmin_found); 185 if (x && x <= mclk_ps && x >= lowest_tCKmin_found ) { 186 lowest_tCKmin_found = x; 187 lowest_tCKmin_CL = i + 2; 188 } 189 } 190 191 debug("lowest_tCKmin_CL = %u\n", lowest_tCKmin_CL); 192 193 return lowest_tCKmin_CL; 194 } 195 196 /* 197 * ddr_compute_dimm_parameters for DDR2 SPD 198 * 199 * Compute DIMM parameters based upon the SPD information in spd. 200 * Writes the results to the dimm_params_t structure pointed by pdimm. 201 * 202 * FIXME: use #define for the retvals 203 */ 204 unsigned int ddr_compute_dimm_parameters(const unsigned int ctrl_num, 205 const ddr2_spd_eeprom_t *spd, 206 dimm_params_t *pdimm, 207 unsigned int dimm_number) 208 { 209 unsigned int retval; 210 211 if (spd->mem_type) { 212 if (spd->mem_type != SPD_MEMTYPE_DDR2) { 213 printf("DIMM %u: is not a DDR2 SPD.\n", dimm_number); 214 return 1; 215 } 216 } else { 217 memset(pdimm, 0, sizeof(dimm_params_t)); 218 return 1; 219 } 220 221 retval = ddr2_spd_check(spd); 222 if (retval) { 223 printf("DIMM %u: failed checksum\n", dimm_number); 224 return 2; 225 } 226 227 /* 228 * The part name in ASCII in the SPD EEPROM is not null terminated. 229 * Guarantee null termination here by presetting all bytes to 0 230 * and copying the part name in ASCII from the SPD onto it 231 */ 232 memset(pdimm->mpart, 0, sizeof(pdimm->mpart)); 233 memcpy(pdimm->mpart, spd->mpart, sizeof(pdimm->mpart) - 1); 234 235 /* DIMM organization parameters */ 236 pdimm->n_ranks = (spd->mod_ranks & 0x7) + 1; 237 pdimm->rank_density = compute_ranksize(spd->mem_type, spd->rank_dens); 238 pdimm->capacity = pdimm->n_ranks * pdimm->rank_density; 239 pdimm->data_width = spd->dataw; 240 pdimm->primary_sdram_width = spd->primw; 241 pdimm->ec_sdram_width = spd->ecw; 242 243 /* These are all the types defined by the JEDEC DDR2 SPD 1.3 spec */ 244 switch (spd->dimm_type) { 245 case DDR2_SPD_DIMMTYPE_RDIMM: 246 case DDR2_SPD_DIMMTYPE_72B_SO_RDIMM: 247 case DDR2_SPD_DIMMTYPE_MINI_RDIMM: 248 /* Registered/buffered DIMMs */ 249 pdimm->registered_dimm = 1; 250 break; 251 252 case DDR2_SPD_DIMMTYPE_UDIMM: 253 case DDR2_SPD_DIMMTYPE_SO_DIMM: 254 case DDR2_SPD_DIMMTYPE_MICRO_DIMM: 255 case DDR2_SPD_DIMMTYPE_MINI_UDIMM: 256 /* Unbuffered DIMMs */ 257 pdimm->registered_dimm = 0; 258 break; 259 260 case DDR2_SPD_DIMMTYPE_72B_SO_CDIMM: 261 default: 262 printf("unknown dimm_type 0x%02X\n", spd->dimm_type); 263 return 1; 264 } 265 266 /* SDRAM device parameters */ 267 pdimm->n_row_addr = spd->nrow_addr; 268 pdimm->n_col_addr = spd->ncol_addr; 269 pdimm->n_banks_per_sdram_device = spd->nbanks; 270 pdimm->edc_config = spd->config; 271 pdimm->burst_lengths_bitmask = spd->burstl; 272 pdimm->row_density = spd->rank_dens; 273 274 /* 275 * Calculate the Maximum Data Rate based on the Minimum Cycle time. 276 * The SPD clk_cycle field (tCKmin) is measured in tenths of 277 * nanoseconds and represented as BCD. 278 */ 279 pdimm->tckmin_x_ps 280 = convert_bcd_tenths_to_cycle_time_ps(spd->clk_cycle); 281 pdimm->tckmin_x_minus_1_ps 282 = convert_bcd_tenths_to_cycle_time_ps(spd->clk_cycle2); 283 pdimm->tckmin_x_minus_2_ps 284 = convert_bcd_tenths_to_cycle_time_ps(spd->clk_cycle3); 285 286 pdimm->tckmax_ps = convert_bcd_tenths_to_cycle_time_ps(spd->tckmax); 287 288 /* 289 * Compute CAS latencies defined by SPD 290 * The SPD caslat_x should have at least 1 and at most 3 bits set. 291 * 292 * If cas_lat after masking is 0, the __ilog2 function returns 293 * 255 into the variable. This behavior is abused once. 294 */ 295 pdimm->caslat_x = __ilog2(spd->cas_lat); 296 pdimm->caslat_x_minus_1 = __ilog2(spd->cas_lat 297 & ~(1 << pdimm->caslat_x)); 298 pdimm->caslat_x_minus_2 = __ilog2(spd->cas_lat 299 & ~(1 << pdimm->caslat_x) 300 & ~(1 << pdimm->caslat_x_minus_1)); 301 302 /* Compute CAS latencies below that defined by SPD */ 303 pdimm->caslat_lowest_derated = compute_derated_DDR2_CAS_latency( 304 get_memory_clk_period_ps(ctrl_num)); 305 306 /* Compute timing parameters */ 307 pdimm->trcd_ps = spd->trcd * 250; 308 pdimm->trp_ps = spd->trp * 250; 309 pdimm->tras_ps = spd->tras * 1000; 310 311 pdimm->twr_ps = spd->twr * 250; 312 pdimm->twtr_ps = spd->twtr * 250; 313 pdimm->trfc_ps = compute_trfc_ps_from_spd(spd->trctrfc_ext, spd->trfc); 314 315 pdimm->trrd_ps = spd->trrd * 250; 316 pdimm->trc_ps = compute_trc_ps_from_spd(spd->trctrfc_ext, spd->trc); 317 318 pdimm->refresh_rate_ps = determine_refresh_rate_ps(spd->refresh); 319 320 pdimm->tis_ps = convert_bcd_hundredths_to_cycle_time_ps(spd->ca_setup); 321 pdimm->tih_ps = convert_bcd_hundredths_to_cycle_time_ps(spd->ca_hold); 322 pdimm->tds_ps 323 = convert_bcd_hundredths_to_cycle_time_ps(spd->data_setup); 324 pdimm->tdh_ps 325 = convert_bcd_hundredths_to_cycle_time_ps(spd->data_hold); 326 327 pdimm->trtp_ps = spd->trtp * 250; 328 pdimm->tdqsq_max_ps = spd->tdqsq * 10; 329 pdimm->tqhs_ps = spd->tqhs * 10; 330 331 return 0; 332 } 333