u-boot/arch/powerpc/cpu/mpc8xxx/ddr/util.c
Kyle Moffett e820a131f4 fsl_ddr: Don't use full 64-bit divides on 32-bit PowerPC
The current FreeScale MPC-8xxx DDR SPD interpreter is using full 64-bit
integer divide operations to convert between nanoseconds and DDR clock
cycles given arbitrary DDR clock frequencies.

Since all of the inputs to this are 32-bit (nanoseconds, clock cycles,
and DDR frequencies), we can easily restructure the computation to use
the "do_div()" function to perform 64-bit/32-bit divide operations.

On 64-bit this change is basically a no-op, because do_div is
implemented as a literal 64-bit divide operation and the instruction
scheduling works out almost the same.

On 32-bit PowerPC a fully accurate 64/64 divide (__udivdi3 in libgcc) is
over 1.1kB of code and thousands of heavily dependent cycles to compute,
all of which is linked from libgcc.  Another 1.2kB of code comes in for
the function __umoddi3.

It should be noted that nothing else in U-Boot or the Linux kernel seems
to require a full 64-bit divide on my 32-bit PowerPC.

Build-and-boot-tested on the HWW-1U-1A board using DDR2 SPD detection.

Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com>
Acked-by: York Sun <yorksun@freescale.com>
Cc: Andy Fleming <afleming@gmail.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
2011-04-04 09:24:43 -05:00

230 lines
5.4 KiB
C

/*
* Copyright 2008-2011 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_law.h>
#include <div64.h>
#include "ddr.h"
/* To avoid 64-bit full-divides, we factor this here */
#define ULL_2e12 2000000000000ULL
#define UL_5pow12 244140625UL
#define UL_2pow13 (1UL << 13)
#define ULL_8Fs 0xFFFFFFFFULL
/*
* Round mclk_ps to nearest 10 ps in memory controller code.
*
* If an imprecise data rate is too high due to rounding error
* propagation, compute a suitably rounded mclk_ps to compute
* a working memory controller configuration.
*/
unsigned int get_memory_clk_period_ps(void)
{
unsigned int data_rate = get_ddr_freq(0);
unsigned int result;
/* Round to nearest 10ps, being careful about 64-bit multiply/divide */
unsigned long long mclk_ps = ULL_2e12;
/* Add 5*data_rate, for rounding */
mclk_ps += 5*(unsigned long long)data_rate;
/* Now perform the big divide, the result fits in 32-bits */
do_div(mclk_ps, data_rate);
result = mclk_ps;
/* We still need to round to 10ps */
return 10 * (result/10);
}
/* Convert picoseconds into DRAM clock cycles (rounding up if needed). */
unsigned int picos_to_mclk(unsigned int picos)
{
unsigned long long clks, clks_rem;
/* Short circuit for zero picos */
if (!picos)
return 0;
/* First multiply the time by the data rate (32x32 => 64) */
clks = picos * (unsigned long long)get_ddr_freq(0);
/*
* Now divide by 5^12 and track the 32-bit remainder, then divide
* by 2*(2^12) using shifts (and updating the remainder).
*/
clks_rem = do_div(clks, UL_5pow12);
clks_rem <<= 13;
clks_rem |= clks & (UL_2pow13-1);
clks >>= 13;
/* If we had a remainder, then round up */
if (clks_rem)
clks++;
/* Clamp to the maximum representable value */
if (clks > ULL_8Fs)
clks = ULL_8Fs;
return (unsigned int) clks;
}
unsigned int mclk_to_picos(unsigned int mclk)
{
return get_memory_clk_period_ps() * mclk;
}
void
__fsl_ddr_set_lawbar(const common_timing_params_t *memctl_common_params,
unsigned int memctl_interleaved,
unsigned int ctrl_num)
{
unsigned long long base = memctl_common_params->base_address;
unsigned long long size = memctl_common_params->total_mem;
/*
* If no DIMMs on this controller, do not proceed any further.
*/
if (!memctl_common_params->ndimms_present) {
return;
}
#if !defined(CONFIG_PHYS_64BIT)
if (base >= CONFIG_MAX_MEM_MAPPED)
return;
if ((base + size) >= CONFIG_MAX_MEM_MAPPED)
size = CONFIG_MAX_MEM_MAPPED - base;
#endif
if (ctrl_num == 0) {
/*
* Set up LAW for DDR controller 1 space.
*/
unsigned int lawbar1_target_id = memctl_interleaved
? LAW_TRGT_IF_DDR_INTRLV : LAW_TRGT_IF_DDR_1;
if (set_ddr_laws(base, size, lawbar1_target_id) < 0) {
printf("%s: ERROR (ctrl #0, intrlv=%d)\n", __func__,
memctl_interleaved);
return ;
}
} else if (ctrl_num == 1) {
if (set_ddr_laws(base, size, LAW_TRGT_IF_DDR_2) < 0) {
printf("%s: ERROR (ctrl #1)\n", __func__);
return ;
}
} else {
printf("%s: unexpected DDR controller number (%u)\n", __func__,
ctrl_num);
}
}
__attribute__((weak, alias("__fsl_ddr_set_lawbar"))) void
fsl_ddr_set_lawbar(const common_timing_params_t *memctl_common_params,
unsigned int memctl_interleaved,
unsigned int ctrl_num);
void board_add_ram_info(int use_default)
{
#if defined(CONFIG_MPC85xx)
volatile ccsr_ddr_t *ddr = (void *)(CONFIG_SYS_MPC85xx_DDR_ADDR);
#elif defined(CONFIG_MPC86xx)
volatile ccsr_ddr_t *ddr = (void *)(CONFIG_SYS_MPC86xx_DDR_ADDR);
#endif
#if (CONFIG_NUM_DDR_CONTROLLERS > 1)
uint32_t cs0_config = in_be32(&ddr->cs0_config);
#endif
uint32_t sdram_cfg = in_be32(&ddr->sdram_cfg);
int cas_lat;
puts(" (DDR");
switch ((sdram_cfg & SDRAM_CFG_SDRAM_TYPE_MASK) >>
SDRAM_CFG_SDRAM_TYPE_SHIFT) {
case SDRAM_TYPE_DDR1:
puts("1");
break;
case SDRAM_TYPE_DDR2:
puts("2");
break;
case SDRAM_TYPE_DDR3:
puts("3");
break;
default:
puts("?");
break;
}
if (sdram_cfg & SDRAM_CFG_32_BE)
puts(", 32-bit");
else if (sdram_cfg & SDRAM_CFG_16_BE)
puts(", 16-bit");
else
puts(", 64-bit");
/* Calculate CAS latency based on timing cfg values */
cas_lat = ((in_be32(&ddr->timing_cfg_1) >> 16) & 0xf) + 1;
if ((in_be32(&ddr->timing_cfg_3) >> 12) & 1)
cas_lat += (8 << 1);
printf(", CL=%d", cas_lat >> 1);
if (cas_lat & 0x1)
puts(".5");
if (sdram_cfg & SDRAM_CFG_ECC_EN)
puts(", ECC on)");
else
puts(", ECC off)");
#if (CONFIG_NUM_DDR_CONTROLLERS > 1)
if (cs0_config & 0x20000000) {
puts("\n");
puts(" DDR Controller Interleaving Mode: ");
switch ((cs0_config >> 24) & 0xf) {
case FSL_DDR_CACHE_LINE_INTERLEAVING:
puts("cache line");
break;
case FSL_DDR_PAGE_INTERLEAVING:
puts("page");
break;
case FSL_DDR_BANK_INTERLEAVING:
puts("bank");
break;
case FSL_DDR_SUPERBANK_INTERLEAVING:
puts("super-bank");
break;
default:
puts("invalid");
break;
}
}
#endif
if ((sdram_cfg >> 8) & 0x7f) {
puts("\n");
puts(" DDR Chip-Select Interleaving Mode: ");
switch(sdram_cfg >> 8 & 0x7f) {
case FSL_DDR_CS0_CS1_CS2_CS3:
puts("CS0+CS1+CS2+CS3");
break;
case FSL_DDR_CS0_CS1:
puts("CS0+CS1");
break;
case FSL_DDR_CS2_CS3:
puts("CS2+CS3");
break;
case FSL_DDR_CS0_CS1_AND_CS2_CS3:
puts("CS0+CS1 and CS2+CS3");
break;
default:
puts("invalid");
break;
}
}
}