--- /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 phys_size_t
+compute_ranksize(unsigned int mem_type, unsigned char row_dens)
+{
+ phys_size_t 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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