u-boot/arch/powerpc/cpu/mpc8xxx/ddr/main.c
York Sun 0a7c5353a4 powerpc/mpc8xxx: Fix DDR 3-way interleaving
Should check if interleaving is enabled before using interleaving mode.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>
2013-05-14 16:00:27 -05:00

662 lines
19 KiB
C

/*
* Copyright 2008-2012 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.
*/
/*
* Generic driver for Freescale DDR/DDR2/DDR3 memory controller.
* Based on code from spd_sdram.c
* Author: James Yang [at freescale.com]
*/
#include <common.h>
#include <i2c.h>
#include <asm/fsl_ddr_sdram.h>
#include <asm/fsl_law.h>
#include "ddr.h"
void fsl_ddr_set_lawbar(
const common_timing_params_t *memctl_common_params,
unsigned int memctl_interleaved,
unsigned int ctrl_num);
void fsl_ddr_set_intl3r(const unsigned int granule_size);
/* processor specific function */
extern void fsl_ddr_set_memctl_regs(const fsl_ddr_cfg_regs_t *regs,
unsigned int ctrl_num);
#if defined(SPD_EEPROM_ADDRESS) || \
defined(SPD_EEPROM_ADDRESS1) || defined(SPD_EEPROM_ADDRESS2) || \
defined(SPD_EEPROM_ADDRESS3) || defined(SPD_EEPROM_ADDRESS4)
#if (CONFIG_NUM_DDR_CONTROLLERS == 1) && (CONFIG_DIMM_SLOTS_PER_CTLR == 1)
u8 spd_i2c_addr[CONFIG_NUM_DDR_CONTROLLERS][CONFIG_DIMM_SLOTS_PER_CTLR] = {
[0][0] = SPD_EEPROM_ADDRESS,
};
#elif (CONFIG_NUM_DDR_CONTROLLERS == 1) && (CONFIG_DIMM_SLOTS_PER_CTLR == 2)
u8 spd_i2c_addr[CONFIG_NUM_DDR_CONTROLLERS][CONFIG_DIMM_SLOTS_PER_CTLR] = {
[0][0] = SPD_EEPROM_ADDRESS1, /* controller 1 */
[0][1] = SPD_EEPROM_ADDRESS2, /* controller 1 */
};
#elif (CONFIG_NUM_DDR_CONTROLLERS == 2) && (CONFIG_DIMM_SLOTS_PER_CTLR == 1)
u8 spd_i2c_addr[CONFIG_NUM_DDR_CONTROLLERS][CONFIG_DIMM_SLOTS_PER_CTLR] = {
[0][0] = SPD_EEPROM_ADDRESS1, /* controller 1 */
[1][0] = SPD_EEPROM_ADDRESS2, /* controller 2 */
};
#elif (CONFIG_NUM_DDR_CONTROLLERS == 2) && (CONFIG_DIMM_SLOTS_PER_CTLR == 2)
u8 spd_i2c_addr[CONFIG_NUM_DDR_CONTROLLERS][CONFIG_DIMM_SLOTS_PER_CTLR] = {
[0][0] = SPD_EEPROM_ADDRESS1, /* controller 1 */
[0][1] = SPD_EEPROM_ADDRESS2, /* controller 1 */
[1][0] = SPD_EEPROM_ADDRESS3, /* controller 2 */
[1][1] = SPD_EEPROM_ADDRESS4, /* controller 2 */
};
#elif (CONFIG_NUM_DDR_CONTROLLERS == 3) && (CONFIG_DIMM_SLOTS_PER_CTLR == 1)
u8 spd_i2c_addr[CONFIG_NUM_DDR_CONTROLLERS][CONFIG_DIMM_SLOTS_PER_CTLR] = {
[0][0] = SPD_EEPROM_ADDRESS1, /* controller 1 */
[1][0] = SPD_EEPROM_ADDRESS2, /* controller 2 */
[2][0] = SPD_EEPROM_ADDRESS3, /* controller 3 */
};
#elif (CONFIG_NUM_DDR_CONTROLLERS == 3) && (CONFIG_DIMM_SLOTS_PER_CTLR == 2)
u8 spd_i2c_addr[CONFIG_NUM_DDR_CONTROLLERS][CONFIG_DIMM_SLOTS_PER_CTLR] = {
[0][0] = SPD_EEPROM_ADDRESS1, /* controller 1 */
[0][1] = SPD_EEPROM_ADDRESS2, /* controller 1 */
[1][0] = SPD_EEPROM_ADDRESS3, /* controller 2 */
[1][1] = SPD_EEPROM_ADDRESS4, /* controller 2 */
[2][0] = SPD_EEPROM_ADDRESS5, /* controller 3 */
[2][1] = SPD_EEPROM_ADDRESS6, /* controller 3 */
};
#endif
static void __get_spd(generic_spd_eeprom_t *spd, u8 i2c_address)
{
int ret = i2c_read(i2c_address, 0, 1, (uchar *)spd,
sizeof(generic_spd_eeprom_t));
if (ret) {
if (i2c_address ==
#ifdef SPD_EEPROM_ADDRESS
SPD_EEPROM_ADDRESS
#elif defined(SPD_EEPROM_ADDRESS1)
SPD_EEPROM_ADDRESS1
#endif
) {
printf("DDR: failed to read SPD from address %u\n",
i2c_address);
} else {
debug("DDR: failed to read SPD from address %u\n",
i2c_address);
}
memset(spd, 0, sizeof(generic_spd_eeprom_t));
}
}
__attribute__((weak, alias("__get_spd")))
void get_spd(generic_spd_eeprom_t *spd, u8 i2c_address);
void fsl_ddr_get_spd(generic_spd_eeprom_t *ctrl_dimms_spd,
unsigned int ctrl_num)
{
unsigned int i;
unsigned int i2c_address = 0;
if (ctrl_num >= CONFIG_NUM_DDR_CONTROLLERS) {
printf("%s unexpected ctrl_num = %u\n", __FUNCTION__, ctrl_num);
return;
}
for (i = 0; i < CONFIG_DIMM_SLOTS_PER_CTLR; i++) {
i2c_address = spd_i2c_addr[ctrl_num][i];
get_spd(&(ctrl_dimms_spd[i]), i2c_address);
}
}
#else
void fsl_ddr_get_spd(generic_spd_eeprom_t *ctrl_dimms_spd,
unsigned int ctrl_num)
{
}
#endif /* SPD_EEPROM_ADDRESSx */
/*
* ASSUMPTIONS:
* - Same number of CONFIG_DIMM_SLOTS_PER_CTLR on each controller
* - Same memory data bus width on all controllers
*
* NOTES:
*
* The memory controller and associated documentation use confusing
* terminology when referring to the orgranization of DRAM.
*
* Here is a terminology translation table:
*
* memory controller/documention |industry |this code |signals
* -------------------------------|-----------|-----------|-----------------
* physical bank/bank |rank |rank |chip select (CS)
* logical bank/sub-bank |bank |bank |bank address (BA)
* page/row |row |page |row address
* ??? |column |column |column address
*
* The naming confusion is further exacerbated by the descriptions of the
* memory controller interleaving feature, where accesses are interleaved
* _BETWEEN_ two seperate memory controllers. This is configured only in
* CS0_CONFIG[INTLV_CTL] of each memory controller.
*
* memory controller documentation | number of chip selects
* | per memory controller supported
* --------------------------------|-----------------------------------------
* cache line interleaving | 1 (CS0 only)
* page interleaving | 1 (CS0 only)
* bank interleaving | 1 (CS0 only)
* superbank interleraving | depends on bank (chip select)
* | interleraving [rank interleaving]
* | mode used on every memory controller
*
* Even further confusing is the existence of the interleaving feature
* _WITHIN_ each memory controller. The feature is referred to in
* documentation as chip select interleaving or bank interleaving,
* although it is configured in the DDR_SDRAM_CFG field.
*
* Name of field | documentation name | this code
* -----------------------------|-----------------------|------------------
* DDR_SDRAM_CFG[BA_INTLV_CTL] | Bank (chip select) | rank interleaving
* | interleaving
*/
const char *step_string_tbl[] = {
"STEP_GET_SPD",
"STEP_COMPUTE_DIMM_PARMS",
"STEP_COMPUTE_COMMON_PARMS",
"STEP_GATHER_OPTS",
"STEP_ASSIGN_ADDRESSES",
"STEP_COMPUTE_REGS",
"STEP_PROGRAM_REGS",
"STEP_ALL"
};
const char * step_to_string(unsigned int step) {
unsigned int s = __ilog2(step);
if ((1 << s) != step)
return step_string_tbl[7];
return step_string_tbl[s];
}
unsigned long long step_assign_addresses(fsl_ddr_info_t *pinfo,
unsigned int dbw_cap_adj[])
{
int i, j;
unsigned long long total_mem, current_mem_base, total_ctlr_mem;
unsigned long long rank_density, ctlr_density = 0;
/*
* If a reduced data width is requested, but the SPD
* specifies a physically wider device, adjust the
* computed dimm capacities accordingly before
* assigning addresses.
*/
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
unsigned int found = 0;
switch (pinfo->memctl_opts[i].data_bus_width) {
case 2:
/* 16-bit */
for (j = 0; j < CONFIG_DIMM_SLOTS_PER_CTLR; j++) {
unsigned int dw;
if (!pinfo->dimm_params[i][j].n_ranks)
continue;
dw = pinfo->dimm_params[i][j].primary_sdram_width;
if ((dw == 72 || dw == 64)) {
dbw_cap_adj[i] = 2;
break;
} else if ((dw == 40 || dw == 32)) {
dbw_cap_adj[i] = 1;
break;
}
}
break;
case 1:
/* 32-bit */
for (j = 0; j < CONFIG_DIMM_SLOTS_PER_CTLR; j++) {
unsigned int dw;
dw = pinfo->dimm_params[i][j].data_width;
if (pinfo->dimm_params[i][j].n_ranks
&& (dw == 72 || dw == 64)) {
/*
* FIXME: can't really do it
* like this because this just
* further reduces the memory
*/
found = 1;
break;
}
}
if (found) {
dbw_cap_adj[i] = 1;
}
break;
case 0:
/* 64-bit */
break;
default:
printf("unexpected data bus width "
"specified controller %u\n", i);
return 1;
}
debug("dbw_cap_adj[%d]=%d\n", i, dbw_cap_adj[i]);
}
current_mem_base = 0ull;
total_mem = 0;
if (pinfo->memctl_opts[0].memctl_interleaving) {
rank_density = pinfo->dimm_params[0][0].rank_density >>
dbw_cap_adj[0];
switch (pinfo->memctl_opts[0].ba_intlv_ctl &
FSL_DDR_CS0_CS1_CS2_CS3) {
case FSL_DDR_CS0_CS1_CS2_CS3:
ctlr_density = 4 * rank_density;
break;
case FSL_DDR_CS0_CS1:
case FSL_DDR_CS0_CS1_AND_CS2_CS3:
ctlr_density = 2 * rank_density;
break;
case FSL_DDR_CS2_CS3:
default:
ctlr_density = rank_density;
break;
}
debug("rank density is 0x%llx, ctlr density is 0x%llx\n",
rank_density, ctlr_density);
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
if (pinfo->memctl_opts[i].memctl_interleaving) {
switch (pinfo->memctl_opts[i].memctl_interleaving_mode) {
case FSL_DDR_CACHE_LINE_INTERLEAVING:
case FSL_DDR_PAGE_INTERLEAVING:
case FSL_DDR_BANK_INTERLEAVING:
case FSL_DDR_SUPERBANK_INTERLEAVING:
total_ctlr_mem = 2 * ctlr_density;
break;
case FSL_DDR_3WAY_1KB_INTERLEAVING:
case FSL_DDR_3WAY_4KB_INTERLEAVING:
case FSL_DDR_3WAY_8KB_INTERLEAVING:
total_ctlr_mem = 3 * ctlr_density;
break;
case FSL_DDR_4WAY_1KB_INTERLEAVING:
case FSL_DDR_4WAY_4KB_INTERLEAVING:
case FSL_DDR_4WAY_8KB_INTERLEAVING:
total_ctlr_mem = 4 * ctlr_density;
break;
default:
panic("Unknown interleaving mode");
}
pinfo->common_timing_params[i].base_address =
current_mem_base;
pinfo->common_timing_params[i].total_mem =
total_ctlr_mem;
total_mem = current_mem_base + total_ctlr_mem;
debug("ctrl %d base 0x%llx\n", i, current_mem_base);
debug("ctrl %d total 0x%llx\n", i, total_ctlr_mem);
} else {
/* when 3rd controller not interleaved */
current_mem_base = total_mem;
total_ctlr_mem = 0;
pinfo->common_timing_params[i].base_address =
current_mem_base;
for (j = 0; j < CONFIG_DIMM_SLOTS_PER_CTLR; j++) {
unsigned long long cap =
pinfo->dimm_params[i][j].capacity >> dbw_cap_adj[i];
pinfo->dimm_params[i][j].base_address =
current_mem_base;
debug("ctrl %d dimm %d base 0x%llx\n", i, j, current_mem_base);
current_mem_base += cap;
total_ctlr_mem += cap;
}
debug("ctrl %d total 0x%llx\n", i, total_ctlr_mem);
pinfo->common_timing_params[i].total_mem =
total_ctlr_mem;
total_mem += total_ctlr_mem;
}
}
} else {
/*
* Simple linear assignment if memory
* controllers are not interleaved.
*/
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
total_ctlr_mem = 0;
pinfo->common_timing_params[i].base_address =
current_mem_base;
for (j = 0; j < CONFIG_DIMM_SLOTS_PER_CTLR; j++) {
/* Compute DIMM base addresses. */
unsigned long long cap =
pinfo->dimm_params[i][j].capacity >> dbw_cap_adj[i];
pinfo->dimm_params[i][j].base_address =
current_mem_base;
debug("ctrl %d dimm %d base 0x%llx\n", i, j, current_mem_base);
current_mem_base += cap;
total_ctlr_mem += cap;
}
debug("ctrl %d total 0x%llx\n", i, total_ctlr_mem);
pinfo->common_timing_params[i].total_mem =
total_ctlr_mem;
total_mem += total_ctlr_mem;
}
}
debug("Total mem by %s is 0x%llx\n", __func__, total_mem);
return total_mem;
}
unsigned long long
fsl_ddr_compute(fsl_ddr_info_t *pinfo, unsigned int start_step,
unsigned int size_only)
{
unsigned int i, j;
unsigned long long total_mem = 0;
fsl_ddr_cfg_regs_t *ddr_reg = pinfo->fsl_ddr_config_reg;
common_timing_params_t *timing_params = pinfo->common_timing_params;
/* data bus width capacity adjust shift amount */
unsigned int dbw_capacity_adjust[CONFIG_NUM_DDR_CONTROLLERS];
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
dbw_capacity_adjust[i] = 0;
}
debug("starting at step %u (%s)\n",
start_step, step_to_string(start_step));
switch (start_step) {
case STEP_GET_SPD:
#if defined(CONFIG_DDR_SPD) || defined(CONFIG_SPD_EEPROM)
/* STEP 1: Gather all DIMM SPD data */
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
fsl_ddr_get_spd(pinfo->spd_installed_dimms[i], i);
}
case STEP_COMPUTE_DIMM_PARMS:
/* STEP 2: Compute DIMM parameters from SPD data */
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
for (j = 0; j < CONFIG_DIMM_SLOTS_PER_CTLR; j++) {
unsigned int retval;
generic_spd_eeprom_t *spd =
&(pinfo->spd_installed_dimms[i][j]);
dimm_params_t *pdimm =
&(pinfo->dimm_params[i][j]);
retval = compute_dimm_parameters(spd, pdimm, i);
#ifdef CONFIG_SYS_DDR_RAW_TIMING
if (!i && !j && retval) {
printf("SPD error on controller %d! "
"Trying fallback to raw timing "
"calculation\n", i);
fsl_ddr_get_dimm_params(pdimm, i, j);
}
#else
if (retval == 2) {
printf("Error: compute_dimm_parameters"
" non-zero returned FATAL value "
"for memctl=%u dimm=%u\n", i, j);
return 0;
}
#endif
if (retval) {
debug("Warning: compute_dimm_parameters"
" non-zero return value for memctl=%u "
"dimm=%u\n", i, j);
}
}
}
#elif defined(CONFIG_SYS_DDR_RAW_TIMING)
case STEP_COMPUTE_DIMM_PARMS:
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
for (j = 0; j < CONFIG_DIMM_SLOTS_PER_CTLR; j++) {
dimm_params_t *pdimm =
&(pinfo->dimm_params[i][j]);
fsl_ddr_get_dimm_params(pdimm, i, j);
}
}
debug("Filling dimm parameters from board specific file\n");
#endif
case STEP_COMPUTE_COMMON_PARMS:
/*
* STEP 3: Compute a common set of timing parameters
* suitable for all of the DIMMs on each memory controller
*/
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
debug("Computing lowest common DIMM"
" parameters for memctl=%u\n", i);
compute_lowest_common_dimm_parameters(
pinfo->dimm_params[i],
&timing_params[i],
CONFIG_DIMM_SLOTS_PER_CTLR);
}
case STEP_GATHER_OPTS:
/* STEP 4: Gather configuration requirements from user */
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
debug("Reloading memory controller "
"configuration options for memctl=%u\n", i);
/*
* This "reloads" the memory controller options
* to defaults. If the user "edits" an option,
* next_step points to the step after this,
* which is currently STEP_ASSIGN_ADDRESSES.
*/
populate_memctl_options(
timing_params[i].all_DIMMs_registered,
&pinfo->memctl_opts[i],
pinfo->dimm_params[i], i);
}
case STEP_ASSIGN_ADDRESSES:
/* STEP 5: Assign addresses to chip selects */
check_interleaving_options(pinfo);
total_mem = step_assign_addresses(pinfo, dbw_capacity_adjust);
case STEP_COMPUTE_REGS:
/* STEP 6: compute controller register values */
debug("FSL Memory ctrl register computation\n");
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
if (timing_params[i].ndimms_present == 0) {
memset(&ddr_reg[i], 0,
sizeof(fsl_ddr_cfg_regs_t));
continue;
}
compute_fsl_memctl_config_regs(
&pinfo->memctl_opts[i],
&ddr_reg[i], &timing_params[i],
pinfo->dimm_params[i],
dbw_capacity_adjust[i],
size_only);
}
default:
break;
}
{
/*
* Compute the amount of memory available just by
* looking for the highest valid CSn_BNDS value.
* This allows us to also experiment with using
* only CS0 when using dual-rank DIMMs.
*/
unsigned int max_end = 0;
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
for (j = 0; j < CONFIG_CHIP_SELECTS_PER_CTRL; j++) {
fsl_ddr_cfg_regs_t *reg = &ddr_reg[i];
if (reg->cs[j].config & 0x80000000) {
unsigned int end;
end = reg->cs[j].bnds & 0xFFF;
if (end > max_end) {
max_end = end;
}
}
}
}
total_mem = 1 + (((unsigned long long)max_end << 24ULL)
| 0xFFFFFFULL);
}
return total_mem;
}
/*
* fsl_ddr_sdram() -- this is the main function to be called by
* initdram() in the board file.
*
* It returns amount of memory configured in bytes.
*/
phys_size_t fsl_ddr_sdram(void)
{
unsigned int i;
unsigned int law_memctl = LAW_TRGT_IF_DDR_1;
unsigned long long total_memory;
fsl_ddr_info_t info;
/* Reset info structure. */
memset(&info, 0, sizeof(fsl_ddr_info_t));
/* Compute it once normally. */
#ifdef CONFIG_FSL_DDR_INTERACTIVE
if (tstc() && (getc() == 'd')) { /* we got a key press of 'd' */
total_memory = fsl_ddr_interactive(&info, 0);
} else if (fsl_ddr_interactive_env_var_exists()) {
total_memory = fsl_ddr_interactive(&info, 1);
} else
#endif
total_memory = fsl_ddr_compute(&info, STEP_GET_SPD, 0);
/* setup 3-way interleaving before enabling DDRC */
if (info.memctl_opts[0].memctl_interleaving) {
switch (info.memctl_opts[0].memctl_interleaving_mode) {
case FSL_DDR_3WAY_1KB_INTERLEAVING:
case FSL_DDR_3WAY_4KB_INTERLEAVING:
case FSL_DDR_3WAY_8KB_INTERLEAVING:
fsl_ddr_set_intl3r(
info.memctl_opts[0].memctl_interleaving_mode);
break;
default:
break;
}
}
/* Program configuration registers. */
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
debug("Programming controller %u\n", i);
if (info.common_timing_params[i].ndimms_present == 0) {
debug("No dimms present on controller %u; "
"skipping programming\n", i);
continue;
}
fsl_ddr_set_memctl_regs(&(info.fsl_ddr_config_reg[i]), i);
}
/* program LAWs */
for (i = 0; i < CONFIG_NUM_DDR_CONTROLLERS; i++) {
if (info.memctl_opts[i].memctl_interleaving) {
switch (info.memctl_opts[i].memctl_interleaving_mode) {
case FSL_DDR_CACHE_LINE_INTERLEAVING:
case FSL_DDR_PAGE_INTERLEAVING:
case FSL_DDR_BANK_INTERLEAVING:
case FSL_DDR_SUPERBANK_INTERLEAVING:
if (i == 0) {
law_memctl = LAW_TRGT_IF_DDR_INTRLV;
fsl_ddr_set_lawbar(&info.common_timing_params[i],
law_memctl, i);
} else if (i == 2) {
law_memctl = LAW_TRGT_IF_DDR_INTLV_34;
fsl_ddr_set_lawbar(&info.common_timing_params[i],
law_memctl, i);
}
break;
case FSL_DDR_3WAY_1KB_INTERLEAVING:
case FSL_DDR_3WAY_4KB_INTERLEAVING:
case FSL_DDR_3WAY_8KB_INTERLEAVING:
law_memctl = LAW_TRGT_IF_DDR_INTLV_123;
if (i == 0) {
fsl_ddr_set_lawbar(&info.common_timing_params[i],
law_memctl, i);
}
break;
case FSL_DDR_4WAY_1KB_INTERLEAVING:
case FSL_DDR_4WAY_4KB_INTERLEAVING:
case FSL_DDR_4WAY_8KB_INTERLEAVING:
law_memctl = LAW_TRGT_IF_DDR_INTLV_1234;
if (i == 0)
fsl_ddr_set_lawbar(&info.common_timing_params[i],
law_memctl, i);
/* place holder for future 4-way interleaving */
break;
default:
break;
}
} else {
switch (i) {
case 0:
law_memctl = LAW_TRGT_IF_DDR_1;
break;
case 1:
law_memctl = LAW_TRGT_IF_DDR_2;
break;
case 2:
law_memctl = LAW_TRGT_IF_DDR_3;
break;
case 3:
law_memctl = LAW_TRGT_IF_DDR_4;
break;
default:
break;
}
fsl_ddr_set_lawbar(&info.common_timing_params[i],
law_memctl, i);
}
}
debug("total_memory by %s = %llu\n", __func__, total_memory);
#if !defined(CONFIG_PHYS_64BIT)
/* Check for 4G or more. Bad. */
if (total_memory >= (1ull << 32)) {
printf("Detected %lld MB of memory\n", total_memory >> 20);
printf(" This U-Boot only supports < 4G of DDR\n");
printf(" You could rebuild it with CONFIG_PHYS_64BIT\n");
printf(" "); /* re-align to match init_func_ram print */
total_memory = CONFIG_MAX_MEM_MAPPED;
}
#endif
return total_memory;
}
/*
* fsl_ddr_sdram_size() - This function only returns the size of the total
* memory without setting ddr control registers.
*/
phys_size_t
fsl_ddr_sdram_size(void)
{
fsl_ddr_info_t info;
unsigned long long total_memory = 0;
memset(&info, 0 , sizeof(fsl_ddr_info_t));
/* Compute it once normally. */
total_memory = fsl_ddr_compute(&info, STEP_GET_SPD, 1);
return total_memory;
}