bank switching
hello linux mtd-guys,
I use the blackfin embedded uClinux environment. I want to change a flash chip-driver to support all four memory banks which are available. Right now, I have a driver which supports 1 memory bank of 2MB. I want to be able to use the other three memory banks also 2-4Mb, 4-6MB and 6-8MB.
Memory bank selection is done by using general io pf4 and pf5. For instance: when pf4 is enabled and pf5 is disabled I am writing in the region 2-4MB.
What would be the correct way to change the chip driver? Do you have a template or tutorial on bank switching?
The driver I want to change is: cfi_cmdset_0001.c
I hope someone can help me.
regards,
Servaes Joordens
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Servaes Joordens ------------------------------------------- M8 Tappersweg 29 2031ET Haarlem The Netherlands Tel: +31 23 5311122 Mob: +31 6 51183379 Fax: +31 23 5322388 VAT-ID: nl-813029090B01 kvk: 34131430 Haarlem
Quoted 5 lines · On Mon, 2007-10-29 at 17:14 +0100, M8 (Servaes Joordens) wrote:
I use the blackfin embedded uClinux environment. I want to change a flash chip-driver to support all four memory banks which are available. Right now, I have a driver which supports 1 memory bank of 2MB. I want to be able to use the other three memory banks also 2-4Mb, 4-6MB and 6-8MB.
Quoted 8 lines
Memory bank selection is done by using general io pf4 and pf5. For
instance: when pf4 is enabled and pf5 is disabled I am writing in the region 2-4MB.What would be the correct way to change the chip driver? Do you have a template or tutorial on bank switching?
The driver I want to change is:
cfi_cmdset_0001.c
No, that's the "chip driver". What you need to provide is a "map driver" which enables physical access (read/write cycles) to the flash device in question.
See the MTD_COMPLEX_MAPPINGS config option, which turns simple things like 'read word' and 'write word' into out-of-line function calls in your map driver. And see the map drivers which do this already, like maps/sbc_gxx.c
Signature · 1 line
dwmw2
Quoted 11 lines · David Woodhouse
Quoted 8 lines · On Mon, 2007-10-29 at 17:14 +0100, M8 (Servaes Joordens) wrote:
I use the blackfin embedded uClinux environment. I want to change a flash chip-driver to support all four memory banks which are available. Right now, I have a driver which supports 1 memory bank of 2MB. I want to be able to use the other three memory banks also 2-4Mb, 4-6MB and 6-8MB.
Memory bank selection is done by using general io pf4 and pf5. For instance: when pf4 is enabled and pf5 is disabled I am writing in the region 2-4MB.
What would be the correct way to change the chip driver? Do you have a template or tutorial on bank switching?
The driver I want to change is:
cfi_cmdset_0001.c
Quoted 10 lines
No, that's the "chip driver". What you need to provide is a "map driver" which enables physical access (read/write cycles) to the flash device in question.
See the
MTD_COMPLEX_MAPPINGSconfig option, which turns simple things like 'read word' and 'write word' into out-of-line function calls in your map driver. And see the map drivers which do this already, likemaps/sbc_gxx.c
Now I enabled the MTD_COMPLEX_MAPPINGS. I changed the code in map_funcs.c for the bank switching, but I get a problem with my ext2 partition in RAM. The RAM memory has another memory mapping (of course). In what file should I make the changes?
I use the following files:
- mtd/cmdlinepart.c
- mtd/chips/cfi_probe.c
- mtd/chips/cfi_cmdset_0001.c
- mtd/maps/uclinux.c (for the root fs in RAM)
- mtd/maps/physmap.c (for the flash_memory)
- mtd/maps/map_funcs.c
My idea is:
- I change the call to simple_map_init(xxx) in physmap.c to my_simple_map_init(xxx)
- I add the bank-switching routines in physmap.c and link them via my_simple_map_init(xxx)
Is this the correct way to do it?
Signature · 13 lines
Servaes Joordens ------------------------------------------- M8 Tappersweg 29 2031ET Haarlem The Netherlands Tel: +31 23 5311122 Mob: +31 6 51183379 Fax: +31 23 5322388 VAT-ID: nl-813029090B01 kvk: 34131430 Haarlem