C3 NOR flash /dev/mtd0 write only?

[Cam Mayor]

For those googling later, here's some more info:
-snapshot from March 25/2003
-from utils directory:
	-unlock works
	-mtd_debug (write/read) works
	-erase fails.  (maybe broken driver erase fcn?)

On Wednesday 27 August 2003 11:18, Cam Mayor wrote:
> Hi all,
>
> I've been pounding on this problem for a while, but the answer has so far
> eluded me.  My /dev/mtd0 (NOR flash) that should be rw is acting as ro.
>
> I am using intel C3 NOR flash (two parallel 32Mbit x 16-B) on a guide A07
> (cs89712 processor, similar to the cdb89712 demo board).  It's been working
> fine for a couple of years, but now we want to do some direct writing of
> the flash from user space. (ie.  cat file > /dev/mtd0)
>
> I can accurately read the contents of the flash with 'cat /dev/mtd0 > file'
> and 'cat /dev/mtdr0 > file'.  /dev/mtd0 is supposed to be rw, but when i do
> cat file > /dev/mtd0, the error i get is:
> cat: write: Read-only file system
>
> I cannot find the reason this is happening.  I believe it is getting marked
> as read only somewhere in the kernel/driver, but i'm not sure where.  If
> you have any ideas, please pass them along.  Here's some system data:
>
> # cat /proc/mtd
> dev:    size   er  name
> mtd0: 00800000 00020000 "flash"
> mtd1: 0000c000 00000010 "SRAM"
> mtd2: 00000080 00010000 "BootROM"
> mtd3: 00800000 00020000 "Physically mapped flash"
> mtd4: 09000000 00004000 "guidenand"
>
> (the following was the output when i enabled DEBUG_CFI_FEATURES in the
> driver) Feature/Command Support: 0066
>      - Chip Erase:         unsupported
>      - Suspend Erase:      supported
>      - Suspend Program:    supported
>      - Legacy Lock/Unlock: unsupported
>      - Queued Erase:       unsupported
>      - Instant block lock: supported
>      - Protection Bits:    supported
>      - Page-mode read:     unsupported
>      - Synchronous read:   unsupported
>   Supported functions after Suspend: 01
>      - Program after Erase Suspend: supported
>   Block Status Register Mask: 0003
>      - Lock Bit Active:      yes
>      - Valid Bit Active:     yes
>   Vcc Logic Supply Optimum Program/Erase Voltage: 0.3 V
>   Vpp Programming Supply Optimum Program/Erase Voltage: 12.0 V
>
> when using the 'erase' command that comes in mtd/utils/erase.c, it provided
> the following output:
> # ./erase /dev/mtd0
> Erase Total 1 Units
> Region 0 is at 0 of 8 sector and with sector size 4000
> Region 1 is at 131072 of 63 sector and with sector size 20000
> Performing Flash Erase of length 16384 at offset 0x0
> MTD Erase failue: Read-only file system
>
> Some of my debug code in the driver to tell me what's what says that the
> flash says the following two flags are defined:
> MTD_CLEAR_BITS defined
> MTD_ERASEABLE defined
> and that the erase, unlock, and write functions exist (they have fcn
> pointer locations, not just NULL)
>
> my relevant /dev entries are as follows:
> # ll /dev/mtd*
> crw-------    1 root     root      90,   0 Aug 26 21:57 /dev/mtd0
> crw-------    1 root     root      90,   2 Aug 26 21:57 /dev/mtd1
> crw-------    1 root     root      90,   4 Aug 26 21:57 /dev/mtd2
> crw-------    1 root     root      90,   6 Aug 26 21:57 /dev/mtd3
> crw-------    1 root     root      90,   8 Aug 26 21:57 /dev/mtd4
> brw-------    1 root     root      31,   0 Aug 26 21:57 /dev/mtdblock0
> brw-------    1 root     root      31,   1 Aug 26 21:57 /dev/mtdblock1
> brw-------    1 root     root      31,   2 Aug 26 21:57 /dev/mtdblock2
> brw-------    1 root     root      31,   3 Aug 26 21:57 /dev/mtdblock3
> crw-------    1 root     root      90,   1 Aug 26 21:57 /dev/mtdr0
> crw-------    1 root     root      90,   3 Aug 26 21:57 /dev/mtdr1
> crw-------    1 root     root      90,   5 Aug 26 21:57 /dev/mtdr2
> crw-------    1 root     root      90,   7 Aug 26 21:57 /dev/mtdr3
> crw-------    1 root     root      90,   9 Aug 26 21:57 /dev/mtdr4
>
> I am using linux 2.4.19-rmk7 with an MTD version that i can't confirm the
> exact date (another developer downloaded an arbitrary version from the mtd
> cvs and added it to ours) ...it is approximately from 2003/03/26.
>
> thanks in advance for any tips/help.
>
> cheers,
> cam

-- 
Cameron Mayor
Iders Incorporated
600A Clifton Street
Winnipeg, MB Canada R3G 2X6
http://www.iders.ca
tel: 204-779-5400 ext 29
fax: 204-779-5444

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