+++ /dev/null
-/*
- * 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 5 bits up to the top. */
- bsize = ((row_dens >> 5) | ((row_dens & 31) << 3));
- bsize <<= 27ULL;
- debug("DDR: DDR II 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;
-}
-
-/*
- * 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. 79-2C
- * Table 40, "DDR2 SDRAM stanadard speed bins and tCK, tRCD, tRP, tRAS,
- * and tRC for corresponding bin"
- *
- * ordinal 2, ddr2_speed_bins[1] contains tCK for CL=3
- * Not certain if any good value exists for CL=2
- */
- /* CL2 CL3 CL4 CL5 CL6 */
-unsigned short ddr2_speed_bins[] = { 0, 5000, 3750, 3000, 2500 };
-
-unsigned int
-compute_derated_DDR2_CAS_latency(unsigned int mclk_ps)
-{
- const unsigned int num_speed_bins = ARRAY_SIZE(ddr2_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 = ddr2_speed_bins[i];
- debug("i=%u, x = %u, lowest_tCKmin_found = %u\n",
- i, x, lowest_tCKmin_found);
- if (x && x <= mclk_ps && x >= lowest_tCKmin_found ) {
- lowest_tCKmin_found = x;
- lowest_tCKmin_CL = i + 2;
- }
- }
-
- debug("lowest_tCKmin_CL = %u\n", lowest_tCKmin_CL);
-
- return lowest_tCKmin_CL;
-}
-
-/*
- * ddr_compute_dimm_parameters for DDR2 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 ddr2_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_DDR2) {
- printf("DIMM %u: is not a DDR2 SPD.\n", dimm_number);
- return 1;
- }
- } else {
- memset(pdimm, 0, sizeof(dimm_params_t));
- return 1;
- }
-
- retval = ddr2_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->mod_ranks & 0x7) + 1;
- pdimm->rank_density = compute_ranksize(spd->mem_type, spd->rank_dens);
- pdimm->capacity = pdimm->n_ranks * pdimm->rank_density;
- pdimm->data_width = spd->dataw;
- pdimm->primary_sdram_width = spd->primw;
- pdimm->ec_sdram_width = spd->ecw;
-
- /* FIXME: what about registered SO-DIMM? */
- switch (spd->dimm_type) {
- case 0x01: /* RDIMM */
- case 0x10: /* Mini-RDIMM */
- pdimm->registered_dimm = 1; /* register buffered */
- break;
-
- case 0x02: /* UDIMM */
- case 0x04: /* SO-DIMM */
- case 0x08: /* Micro-DIMM */
- case 0x20: /* Mini-UDIMM */
- pdimm->registered_dimm = 0; /* unbuffered */
- break;
-
- default:
- printf("unknown dimm_type 0x%02X\n", spd->dimm_type);
- return 1;
- break;
- }
-
- /* 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->rank_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 = convert_bcd_tenths_to_cycle_time_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_DDR2_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 = spd->twr * 250;
- pdimm->tWTR_ps = spd->twtr * 250;
- pdimm->tRFC_ps = compute_trfc_ps_from_spd(spd->trctrfc_ext, spd->trfc);
-
- pdimm->tRRD_ps = spd->trrd * 250;
- pdimm->tRC_ps = compute_trc_ps_from_spd(spd->trctrfc_ext, 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 = spd->trtp * 250;
- pdimm->tDQSQ_max_ps = spd->tdqsq * 10;
- pdimm->tQHS_ps = spd->tqhs * 10;
-
- return 0;
-}
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