// SPDX-License-Identifier: GPL-2.0 /* * Copyright 2008 Freescale Semiconductor, Inc. */ #include #include #include #include /* * Calculate the Density of each Physical Rank. * Returned size is in bytes. * * Study these table from Byte 31 of JEDEC SPD Spec. * * DDR I DDR II * Bit Size Size * --- ----- ------ * 7 high 512MB 512MB * 6 256MB 256MB * 5 128MB 128MB * 4 64MB 16GB * 3 32MB 8GB * 2 16MB 4GB * 1 2GB 2GB * 0 low 1GB 1GB * * Reorder Table to be linear by stripping the bottom * 2 or 5 bits off and shifting them up to the top. */ static unsigned long long compute_ranksize(unsigned int mem_type, unsigned char row_dens) { unsigned long long bsize; /* Bottom 2 bits up to the top. */ bsize = ((row_dens >> 2) | ((row_dens & 3) << 6)); bsize <<= 24ULL; debug("DDR: DDR I rank density = 0x%16llx\n", bsize); return bsize; } /* * Convert a two-nibble BCD value into a cycle time. * While the spec calls for nano-seconds, picos are returned. * * This implements the tables for bytes 9, 23 and 25 for both * DDR I and II. No allowance for distinguishing the invalid * fields absent for DDR I yet present in DDR II is made. * (That is, cycle times of .25, .33, .66 and .75 ns are * allowed for both DDR II and I.) */ static unsigned int convert_bcd_tenths_to_cycle_time_ps(unsigned int spd_val) { /* Table look up the lower nibble, allow DDR I & II. */ unsigned int tenths_ps[16] = { 0, 100, 200, 300, 400, 500, 600, 700, 800, 900, 250, /* This and the next 3 entries valid ... */ 330, /* ... only for tCK calculations. */ 660, 750, 0, /* undefined */ 0 /* undefined */ }; unsigned int whole_ns = (spd_val & 0xF0) >> 4; unsigned int tenth_ns = spd_val & 0x0F; unsigned int ps = whole_ns * 1000 + tenths_ps[tenth_ns]; return ps; } static unsigned int convert_bcd_hundredths_to_cycle_time_ps(unsigned int spd_val) { unsigned int tenth_ns = (spd_val & 0xF0) >> 4; unsigned int hundredth_ns = spd_val & 0x0F; unsigned int ps = tenth_ns * 100 + hundredth_ns * 10; return ps; } static unsigned int byte40_table_ps[8] = { 0, 250, 330, 500, 660, 750, 0, /* supposed to be RFC, but not sure what that means */ 0 /* Undefined */ }; static unsigned int compute_trfc_ps_from_spd(unsigned char trctrfc_ext, unsigned char trfc) { return ((trctrfc_ext & 0x1) * 256 + trfc) * 1000 + byte40_table_ps[(trctrfc_ext >> 1) & 0x7]; } static unsigned int compute_trc_ps_from_spd(unsigned char trctrfc_ext, unsigned char trc) { return trc * 1000 + byte40_table_ps[(trctrfc_ext >> 4) & 0x7]; } /* * tCKmax from DDR I SPD Byte 43 * * Bits 7:2 == whole ns * Bits 1:0 == quarter ns * 00 == 0.00 ns * 01 == 0.25 ns * 10 == 0.50 ns * 11 == 0.75 ns * * Returns picoseconds. */ static unsigned int compute_tckmax_from_spd_ps(unsigned int byte43) { return (byte43 >> 2) * 1000 + (byte43 & 0x3) * 250; } /* * Determine Refresh Rate. Ignore self refresh bit on DDR I. * Table from SPD Spec, Byte 12, converted to picoseconds and * filled in with "default" normal values. */ static unsigned int determine_refresh_rate_ps(const unsigned int spd_refresh) { unsigned int refresh_time_ps[8] = { 15625000, /* 0 Normal 1.00x */ 3900000, /* 1 Reduced .25x */ 7800000, /* 2 Extended .50x */ 31300000, /* 3 Extended 2.00x */ 62500000, /* 4 Extended 4.00x */ 125000000, /* 5 Extended 8.00x */ 15625000, /* 6 Normal 1.00x filler */ 15625000, /* 7 Normal 1.00x filler */ }; return refresh_time_ps[spd_refresh & 0x7]; } /* * The purpose of this function is to compute a suitable * CAS latency given the DRAM clock period. The SPD only * defines at most 3 CAS latencies. Typically the slower in * frequency the DIMM runs at, the shorter its CAS latency can be. * If the DIMM is operating at a sufficiently low frequency, * it may be able to run at a CAS latency shorter than the * shortest SPD-defined CAS latency. * * If a CAS latency is not found, 0 is returned. * * Do this by finding in the standard speed bin table the longest * tCKmin that doesn't exceed the value of mclk_ps (tCK). * * An assumption made is that the SDRAM device allows the * CL to be programmed for a value that is lower than those * advertised by the SPD. This is not always the case, * as those modes not defined in the SPD are optional. * * CAS latency de-rating based upon values JEDEC Standard No. 79-E * Table 11. * * ordinal 2, ddr1_speed_bins[1] contains tCK for CL=2 */ /* CL2.0 CL2.5 CL3.0 */ unsigned short ddr1_speed_bins[] = {0, 7500, 6000, 5000 }; unsigned int compute_derated_DDR1_CAS_latency(unsigned int mclk_ps) { const unsigned int num_speed_bins = ARRAY_SIZE(ddr1_speed_bins); unsigned int lowest_tCKmin_found = 0; unsigned int lowest_tCKmin_CL = 0; unsigned int i; debug("mclk_ps = %u\n", mclk_ps); for (i = 0; i < num_speed_bins; i++) { unsigned int x = ddr1_speed_bins[i]; debug("i=%u, x = %u, lowest_tCKmin_found = %u\n", i, x, lowest_tCKmin_found); if (x && lowest_tCKmin_found <= x && x <= mclk_ps) { lowest_tCKmin_found = x; lowest_tCKmin_CL = i + 1; } } debug("lowest_tCKmin_CL = %u\n", lowest_tCKmin_CL); return lowest_tCKmin_CL; } /* * ddr_compute_dimm_parameters for DDR1 SPD * * Compute DIMM parameters based upon the SPD information in spd. * Writes the results to the dimm_params_t structure pointed by pdimm. * * FIXME: use #define for the retvals */ unsigned int ddr_compute_dimm_parameters(const unsigned int ctrl_num, const ddr1_spd_eeprom_t *spd, dimm_params_t *pdimm, unsigned int dimm_number) { unsigned int retval; if (spd->mem_type) { if (spd->mem_type != SPD_MEMTYPE_DDR) { printf("DIMM %u: is not a DDR1 SPD.\n", dimm_number); return 1; } } else { memset(pdimm, 0, sizeof(dimm_params_t)); return 1; } retval = ddr1_spd_check(spd); if (retval) { printf("DIMM %u: failed checksum\n", dimm_number); return 2; } /* * The part name in ASCII in the SPD EEPROM is not null terminated. * Guarantee null termination here by presetting all bytes to 0 * and copying the part name in ASCII from the SPD onto it */ memset(pdimm->mpart, 0, sizeof(pdimm->mpart)); memcpy(pdimm->mpart, spd->mpart, sizeof(pdimm->mpart) - 1); /* DIMM organization parameters */ pdimm->n_ranks = spd->nrows; pdimm->rank_density = compute_ranksize(spd->mem_type, spd->bank_dens); pdimm->capacity = pdimm->n_ranks * pdimm->rank_density; pdimm->data_width = spd->dataw_lsb; pdimm->primary_sdram_width = spd->primw; pdimm->ec_sdram_width = spd->ecw; /* * FIXME: Need to determine registered_dimm status. * 1 == register buffered * 0 == unbuffered */ pdimm->registered_dimm = 0; /* unbuffered */ /* SDRAM device parameters */ pdimm->n_row_addr = spd->nrow_addr; pdimm->n_col_addr = spd->ncol_addr; pdimm->n_banks_per_sdram_device = spd->nbanks; pdimm->edc_config = spd->config; pdimm->burst_lengths_bitmask = spd->burstl; /* * Calculate the Maximum Data Rate based on the Minimum Cycle time. * The SPD clk_cycle field (tCKmin) is measured in tenths of * nanoseconds and represented as BCD. */ pdimm->tckmin_x_ps = convert_bcd_tenths_to_cycle_time_ps(spd->clk_cycle); pdimm->tckmin_x_minus_1_ps = convert_bcd_tenths_to_cycle_time_ps(spd->clk_cycle2); pdimm->tckmin_x_minus_2_ps = convert_bcd_tenths_to_cycle_time_ps(spd->clk_cycle3); pdimm->tckmax_ps = compute_tckmax_from_spd_ps(spd->tckmax); /* * Compute CAS latencies defined by SPD * The SPD caslat_x should have at least 1 and at most 3 bits set. * * If cas_lat after masking is 0, the __ilog2 function returns * 255 into the variable. This behavior is abused once. */ pdimm->caslat_x = __ilog2(spd->cas_lat); pdimm->caslat_x_minus_1 = __ilog2(spd->cas_lat & ~(1 << pdimm->caslat_x)); pdimm->caslat_x_minus_2 = __ilog2(spd->cas_lat & ~(1 << pdimm->caslat_x) & ~(1 << pdimm->caslat_x_minus_1)); /* Compute CAS latencies below that defined by SPD */ pdimm->caslat_lowest_derated = compute_derated_DDR1_CAS_latency( get_memory_clk_period_ps(ctrl_num)); /* Compute timing parameters */ pdimm->trcd_ps = spd->trcd * 250; pdimm->trp_ps = spd->trp * 250; pdimm->tras_ps = spd->tras * 1000; pdimm->twr_ps = mclk_to_picos(ctrl_num, 3); pdimm->twtr_ps = mclk_to_picos(ctrl_num, 1); pdimm->trfc_ps = compute_trfc_ps_from_spd(0, spd->trfc); pdimm->trrd_ps = spd->trrd * 250; pdimm->trc_ps = compute_trc_ps_from_spd(0, spd->trc); pdimm->refresh_rate_ps = determine_refresh_rate_ps(spd->refresh); pdimm->tis_ps = convert_bcd_hundredths_to_cycle_time_ps(spd->ca_setup); pdimm->tih_ps = convert_bcd_hundredths_to_cycle_time_ps(spd->ca_hold); pdimm->tds_ps = convert_bcd_hundredths_to_cycle_time_ps(spd->data_setup); pdimm->tdh_ps = convert_bcd_hundredths_to_cycle_time_ps(spd->data_hold); pdimm->trtp_ps = mclk_to_picos(ctrl_num, 2); /* By the book. */ pdimm->tdqsq_max_ps = spd->tdqsq * 10; pdimm->tqhs_ps = spd->tqhs * 10; return 0; }