I am working on a board with: * 1 mpc8270 * 2 Spansion S29JL064H memory devices - connected in parallel [(32x16): 16 MB in 142 Sectors] - seemingly wired as little endian devices
Working with u-boot-1.2.0, I created a unique board type loosely based upon the work done for the mpc8260ads board. Because the flash is CFI compliant I would like to use the common CFI driver rather than a custom driver. By enabling the common CFI driver I have encountered some endian issues that have broken 'saveenv'.
When I first enabled the common CFI driver, it reported that 'CFI detect' failed to identify the flash.
## Unknown FLASH on Bank 1 - Size = 0x00000000 = 0 MB *** failed *** ### ERROR ### Please RESET the board ###
I enabled debugging in the driver directory which pointed to the source of the problem:
FLASH: flash detect cfi ... fwc addr ff000000 cmd 0 00000000 32bit x 16 bit fwc addr ff000154 cmd 98 00980098 32bit x 16 bit is= cmd 51(Q) addr ff000040 is= 00000000 00510051 ...
Using "peak and poke" I was able to ascertain that:
* the CFI query command that works with my board is '98009800', not '00980098' * the data at ff000040 should be '51005100', not '00510051'
==> looks like an Endian problem of some sort.
The CFI flash driver source, drivers/cfi_flash.c, supports little ENDIAN when a preprocessor macro, __LITTLE_ENDIAN, is defined. As quick an dirty hack I edited the Makefile in the drivers directory and added '-D__LITTLE_ENDIAN' to the CFLAGS list. This hack actually 'worked':
[from flinfo] Bank # 1: CFI conformant FLASH (32 x 16) Size: 16 MB in 142 Sectors AMD Standard command set, Manufacturer ID: 0x01, Device ID 0x7E0201 Erase timeout: 8192 ms, write timeout: 1 ms
The driver Makefile hack is far too encompassing, which leads to a question:
"Where is the right place to define this preprocessor macro definition?"
The board configuration header file is the obvious place. However, defining __LITTLE_ENDIAN in a the board configuration header file for a board with a big ENDIAN processor causes all sorts of mischief. Changing the name of the __LITTLE_ENDIAN macro in drivers/cfi_flash.c to something less generic would also be a bad idea.
I used the following approach which 'works' on this particular board.
* in the board configuration header file
#define CFG_FLASH_LITTLE_ENDIAN
* in drivers/cfi_flash.c
--- u-boot-1.2.0/drivers/cfi_flash.c.orig 2007-10-26 14:36:00.060179333 -0400 +++ u-boot-1.2.0/drivers/cfi_flash.c 2007-10-26 15:18:01.485629019 -0400 @@ -56,6 +56,10 @@ * */
+#ifdef CFG_FLASH_LITTLE_ENDIAN +#define __LITTLE_ENDIAN +#endif + #ifndef CFG_FLASH_BANKS_LIST #define CFG_FLASH_BANKS_LIST { CFG_FLASH_BASE } #endif
All seemed well until I ran 'saveenv' from the u-boot prompt. An odd thing happened:
All of the words in u-boot environment stored in flash changed their endianness.
For example,
==> md ffffc000 ffffc000: abb4f7d5 626f6f74 64656c61 793d3500 ....bootdelay=5. ffffc010: 65746861 63743d46 43433120 45544845 ethact=FCC1 ETHE ffffc020: 524e4554 006d7464 70617274 733d7068 RNET.mtdparts=ph ffffc030: 79733a32 35366b40 30287562 6f6f7429 ys:256k@0(uboot) ffffc040: 2c373535 326b4032 35366b28 70617274 ,7552k@256k(part ffffc050: 31292c37 3535326b 40373830 386b2870 1),7552k@7808k(p ffffc060: 61727432 292c3839 366b4031 35333630 art2),896k@15360 ...
became
==> md ffffc000 90 ffffc000: d5f7b4ab 746f6f62 616c6564 00353d79 ....toobaled.5=y ffffc010: 61687465 463d7463 20314343 45485445 ahteF=tc 1CCEHTE ffffc020: 54454e52 64746d00 74726170 68703d73 TENRdtm.traphp=s ffffc030: 323a7379 406b3635 62752830 29746f6f 2:sy@k65bu(0)too ffffc040: 3535372c 32406b32 286b3635 74726170 557,2@k2(k65trap ffffc050: 372c2931 6b323535 30383740 70286b38 7,)1k255087@p(k8 ffffc060: 32747261 39382c29 31406b36 30363335 2tra98,)1@k60635 ...
So... My '__LITTLE_ENDIAN' hack is not correct.
The question is,
"What is the right way to configure/enable the common CFI driver for a board with a big endian processor and little endian wired flash?
Thoughts???
-Joseph