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u-boot/doc/README.sbc8548
Paul Gortmaker 3e3262bd14 sbc8548: enable support for hardware SPD errata workaround 
Existing boards by default have an issue where the LBC SDRAM
SPD EEPROM and the DDR2 SDRAM SPD EEPROM both land at 0x51.

After the hardware modification listed in the README is made,
then the DDR2 SPD EEPROM appears at 0x53.  So this implements
a board specific get_spd() by taking advantage of the existing
weak linkage, that 1st tries reading at 0x53 and then if that
fails, it falls back to the old 0x51.

Since the old dependency issue of "SPD implies no LBC SDRAM"
gets removed with the hardware errata fix, remove that restriction
in the code, so both LBC SDRAM and SPD can be selected.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
2012-01-11 13:59:14 -06:00

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Intro:
======
The SBC8548 is a stand alone single board computer with a 1GHz
MPC8548 CPU, 8MB boot flash, 64MB user flash and, 256MB DDR2 400MHz
memory. It also has 128MB SDRAM 100MHz LBC memory, with both a PCI-e,
and a PCI-X slot, dual mini-DB9 for UART, and dual RJ-45 for eTSEC
ethernet connections.
U-boot Configuration:
=====================
The following possible u-boot configuration targets are available:
1) sbc8548_config
2) sbc8548_PCI_33_config
3) sbc8548_PCI_66_config
4) sbc8548_PCI_33_PCIE_config
5) sbc8548_PCI_66_PCIE_config
Generally speaking, most people should choose to use #5. Details
of each choice are listed below.
Choice #1 does not enable CONFIG_PCI, and assumes that the PCI slot
will be left empty (M66EN high), and so the board will operate with
a base clock of 66MHz. Note that you need both PCI enabled in u-boot
and linux in order to have functional PCI under linux.
The second enables PCI support and builds for a 33MHz clock rate. Note
that if a 33MHz 32bit card is inserted in the slot, then the whole board
will clock down to a 33MHz base clock instead of the default 66MHz. This
will change the baud clocks and mess up your serial console output if you
were previously running at 66MHz. If you want to use a 33MHz PCI card,
then you should build a U-Boot with a _PCI_33_ config and store this
to flash prior to powering down the board and inserting the 33MHz PCI
card. [The above discussion assumes that the SW2[1-4] has not been changed
to reflect a different CCB:SYSCLK ratio]
The third option builds PCI support in, and leaves the clocking at the
default 66MHz. Options four and five are just repeats of option two
and three, but with PCI-e support enabled as well.
PCI output listing with an intel e1000 PCI-x and a Syskonnect SK-9Exx
is shown below for sbc8548_PCI_66_PCIE_config. (Note that PCI-e with
a 33MHz PCI configuration is currently untested.)
=> pci 0
Scanning PCI devices on bus 0
BusDevFun VendorId DeviceId Device Class Sub-Class
_____________________________________________________________
00.00.00 0x1057 0x0012 Processor 0x20
00.01.00 0x8086 0x1026 Network controller 0x00
=> pci 1
Scanning PCI devices on bus 1
BusDevFun VendorId DeviceId Device Class Sub-Class
_____________________________________________________________
01.00.00 0x1957 0x0012 Processor 0x20
=> pci 2
Scanning PCI devices on bus 2
BusDevFun VendorId DeviceId Device Class Sub-Class
_____________________________________________________________
02.00.00 0x1148 0x9e00 Network controller 0x00
=>
Memory Size and using SPD:
==========================
The default configuration uses hard coded memory configuration settings
for 256MB of DDR2 @400MHz. It does not by default use the DDR2 SPD
EEPROM data to read what memory is installed.
There is a hardware errata, which causes the older local bus SDRAM
SPD EEPROM to land at the same address as the DDR2 SPD EEPROM, so
that the SPD data can not be read reliably. You can test if your
board has the errata fix by running "i2c probe". If you see 0x53
as a valid device, it has been fixed. If you only see 0x50, 0x51
then your board does not have the fix.
You can also visually inspect the board to see if this hardware
fix has been applied:
1) Remove R314 (RES-R0174-033, 1K, 0603). R314 is located on
the back of the PCB behind the DDR SDRAM SODIMM connector.
2) Solder RES-R0174-033 (1K, 0603) resistor from R314 pin 2 pad
to R313 pin 2. Pin 2 for each resistor is the end of the
resistor closest to the CPU.
Boards without the mod will have R314 and R313 in parallel, like "||".
After the mod, they will be touching and form an "L" shape.
If you want to upgrade to larger RAM size, you can simply enable
#define CONFIG_SPD_EEPROM
#define CONFIG_DDR_SPD
in include/configs/sbc8548.h file. (The lines are already there
but listed as #undef).
If you did the i2c test, and your board does not have the errata
fix, then you will have to physically remove the LBC 128MB DIMM
from the board's socket to resolve the above i2c address overlap
issue and allow SPD autodetection of RAM to work.
Updating U-boot with U-boot:
============================
Note that versions of u-boot up to and including 2009.08 had u-boot stored
at 0xfff8_0000 -> 0xffff_ffff (512k). Currently it is being stored from
0xfffa_0000 -> 0xffff_ffff (384k). If you use an old macro/script to
update u-boot with u-boot and it uses the old address, you will render
your board inoperable, and you will require JTAG recovery.
The following steps list how to update with the current address:
tftp u-boot.bin
md 200000 10
protect off all
erase fffa0000 ffffffff
cp.b 200000 fffa0000 60000
md fffa0000 10
protect on all
The "md" steps in the above are just a precautionary step that allow
you to confirm the u-boot version that was downloaded, and then confirm
that it was copied to flash.
The above assumes that you are using the default board settings which
have u-boot in the 8MB flash, tied to /CS0.
If you are running the default 8MB /CS0 settings but want to store an
image in the SODIMM that is built with CONFIG_SYS_ALT_BOOT enabled,
(as a backup, etc) then the steps will become:
tftp u-boot.bin
md 200000 10
protect off all
era eff00000 efffffff
cp.b 200000 eff00000 100000
md eff00000 10
protect on all
Finally, if you are running the alternate 64MB /CS0 settings and want
to update the in-use u-boot image, then (again with CONFIG_SYS_ALT_BOOT
enabled) the steps will become:
tftp u-boot.bin
md 200000 10
protect off all
era fff00000 ffffffff
cp.b 200000 fff00000 100000
md fff00000 10
protect on all
Hardware Reference:
===================
The following contains some summary information on hardware settings
that are relevant to u-boot, based on the board manual. For the
most up to date and complete details of the board, please request the
reference manual ERG-00327-001.pdf from www.windriver.com
Boot flash:
intel V28F640Jx, 8192x8 (one device) at 0xff80_0000
Sodimm flash:
intel V28F128Jx, 16384x8 (4 devices) at 0xfb80_0000
Note that this address reflects the default setting for
the JTAG debugging tools, but since the alignment is
rather inconvenient, u-boot puts it at 0xec00_0000.
Jumpers:
Jumper Name ON OFF
----------------------------------------------------------------
JP12 CS0/CS6 swap see note[*] see note[*]
JP13 SODIMM flash write OK writes disabled
write prot.
JP14 HRESET/TRST joined isolated
JP15 PWR ON when AC pwr use S1 for on/off
JP16 Demo LEDs lit not lit
JP19 PCI mode PCI PCI-X
[*]JP12, when jumpered parallel to the SODIMM, puts the boot flash
onto /CS0 and the SODIMM flash on /CS6 (default). When JP12
is jumpered parallel to the LBC-SDRAM, then /CS0 is for the
SODIMM flash and /CS6 is for the boot flash. Note that in this
alternate setting, you also need to switch SW2.8 to ON.
See the setting CONFIG_SYS_ALT_BOOT if you want to use this setting
and boot u-boot from the 64MB SODIMM
Switches:
The defaults are marked with a *
Name Desc. ON OFF
------------------------------------------------------------------
S1 Pwr toggle n/a n/a
SW2.1 CFG_SYS_PLL0 1 0*
SW2.2 CFG_SYS_PLL1 1* 0
SW2.3 CFG_SYS_PLL2 1* 0
SW2.4 CFG_SYS_PLL3 1 0*
SW2.5 CFG_CORE_PLL0 1* 0
SW2.6 CFG_CORE_PLL1 1 0*
SW2.7 CFG_CORE_PLL2 1* 0
SW2.8 CFG_ROM_LOC1 1 0*
SW3.1 CFG_HOST_AGT0 1* 0
SW3.2 CFG_HOST_AGT1 1* 0
SW3.3 CFG_HOST_AGT2 1* 0
SW3.4 CFG_IO_PORTS0 1* 0
SW3.5 CFG_IO_PORTS0 1 0*
SW3.6 CFG_IO_PORTS0 1 0*
SerDes CLK(MHz) SW5.1 SW5.2
----------------------------------------------
25 0 0
100* 1 0
125 0 1
200 1 1
SerDes CLK spread SW5.3 SW5.4
----------------------------------------------
+/- 0.25% 0 0
-0.50% 1 0
-0.75% 0 1
No Spread* 1 1
SW4 settings are readable from the EPLD and are currently not used for
any hardware settings (i.e. user configuration switches).
LEDs:
Name Desc. ON OFF
------------------------------------------------------------------
D13 PCI/PCI-X PCI-X PCI
D14 3.3V PWR 3.3V no power
D15 SYSCLK 66MHz 33MHz
Default Memory Map:
start end CS<n> width Desc.
----------------------------------------------------------------------
0000_0000 0fff_ffff MCS0,1 64 DDR2 (256MB)
f000_0000 f7ff_ffff CS3,4 32 LB SDRAM (128MB)
f800_0000 f8b0_1fff CS5 - EPLD
fb80_0000 ff7f_ffff CS6 32 SODIMM flash (64MB) [*]
ff80_0000 ffff_ffff CS0 8 Boot flash (8MB)
[*] fb80 represents the default programmed by WR JTAG register files,
but u-boot places the flash at either ec00 or fc00 based on JP12.
The EPLD on CS5 demuxes the following devices at the following offsets:
offset size width device
--------------------------------------------------------
0 1fff 8 7 segment display LED
10_0000 1fff 4 user switches
30_0000 1fff 4 HW Rev. register
b0_0000 1fff 8 8kB EEPROM
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