gfiber / uboot / prism / 9833b086650dbfb7d1cbb5cf11ba6da220681db2 / . / cpu / mpc8xxx / ddr / ddr1_dimm_params.c

/* | |

* Copyright 2008 Freescale Semiconductor, Inc. | |

* | |

* This program is free software; you can redistribute it and/or | |

* modify it under the terms of the GNU General Public License | |

* Version 2 as published by the Free Software Foundation. | |

*/ | |

#include <common.h> | |

#include <asm/fsl_ddr_sdram.h> | |

#include "ddr.h" | |

/* | |

* 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%08x\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) | |

{ | |

unsigned int trfc_ps; | |

trfc_ps = (((trctrfc_ext & 0x1) * 256) + trfc) * 1000 | |

+ byte40_table_ps[(trctrfc_ext >> 1) & 0x7]; | |

return trfc_ps; | |

} | |

static unsigned int | |

compute_trc_ps_from_spd(unsigned char trctrfc_ext, unsigned char trc) | |

{ | |

unsigned int trc_ps; | |

trc_ps = trc * 1000 + byte40_table_ps[(trctrfc_ext >> 4) & 0x7]; | |

return trc_ps; | |

} | |

/* | |

* 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 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; | |

pdimm->row_density = spd->bank_dens; | |

/* | |

* 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()); | |

/* 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(3); | |

pdimm->tWTR_ps = mclk_to_picos(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(2); /* By the book. */ | |

pdimm->tDQSQ_max_ps = spd->tdqsq * 10; | |

pdimm->tQHS_ps = spd->tqhs * 10; | |

return 0; | |

} |