File System on 64-bit-bus-width Flash memory

File System on 64-bit-bus-width Flash memory

[Sangmoon Kim]

Hi,
I want to make a flash file system on a custom MPC755 board with a 64-bit (bus width) flash memory.
I set CONFIG_MTD_PHYSMAP_BUSWIDTH = 8 at kernel configure, and when it boots the following message appears.

physmap flash device: 400000 at 7c000000
genprobe_new_chip called with unsupported buswidth 8
CFI: Found no Physically mapped flash device at location zero

Is it possible to make a flash file system with a flash memory of  64 bit bus width? If possible, what's the method? Please let me know.

- Sangmoon Kim -

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Re: File System on 64-bit-bus-width Flash memory

[Wolfgang Denk]

In message <000b01c1fb37$50751cf0$1a11efcb@industrialDiv.hanasys.co.kr> you wrote:
>
> Hi,
> I want to make a flash file system on a custom MPC755 board with a 64-bit (bus width) flash memory.
> I set CONFIG_MTD_PHYSMAP_BUSWIDTH = 8 at kernel configure, and when it boots the following message appears.
>
> physmap flash device: 400000 at 7c000000
> genprobe_new_chip called with unsupported buswidth 8

Seems your MTD drivers are missing support for 64 bit buswidth.

> Is it possible to make a flash file system with a flash memory of  64 bit bus width? If possible, what's the method? Please let me know.

We implemented this long ago. See our kernel source tree at
ftp://ftp.denx.de/pub/LinuxPPC/usr/src/

For example:

...
TQM8260 flash bank 0: Using static image partition definition
Creating 4 MTD partitions on "TQM8260 Bank 0":
0x00000000-0x00040000 : "ppcboot"
0x00040000-0x00100000 : "kernel"
0x00100000-0x00400000 : "initrd"
0x00400000-0x00800000 : "jffs"
...

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
There are two ways to write error-free programs. Only the  third  one
works.

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RE: File System on 64-bit-bus-width Flash memory

[Allen Curtis]

MTD has support for 64-bit bus. They have not pushed the code the main tree.
Goto www.infradead.org and checkout the CVS tree. (I have not personally
used this code version. I implemented modified MTD myself last December)

> -----Original Message-----
> From: owner-linuxppc-embedded@lists.linuxppc.org
> [mailto:owner-linuxppc-embedded@lists.linuxppc.org]On Behalf Of Wolfgang
> Denk
> Sent: Tuesday, May 14, 2002 4:14 AM
> To: Sangmoon Kim
> Cc: linuxppc-embedded@lists.linuxppc.org
> Subject: Re: File System on 64-bit-bus-width Flash memory
>
>
>
> In message
> <000b01c1fb37$50751cf0$1a11efcb@industrialDiv.hanasys.co.kr> you wrote:
> >
> > Hi,
> > I want to make a flash file system on a custom MPC755 board
> with a 64-bit (bus width) flash memory.
> > I set CONFIG_MTD_PHYSMAP_BUSWIDTH = 8 at kernel configure, and
> when it boots the following message appears.
> >
> > physmap flash device: 400000 at 7c000000
> > genprobe_new_chip called with unsupported buswidth 8
>
> Seems your MTD drivers are missing support for 64 bit buswidth.
>
> > Is it possible to make a flash file system with a flash memory
> of  64 bit bus width? If possible, what's the method? Please let me know.
>
> We implemented this long ago. See our kernel source tree at
> ftp://ftp.denx.de/pub/LinuxPPC/usr/src/
>
> For example:
>
> ...
> TQM8260 flash bank 0: Using static image partition definition
> Creating 4 MTD partitions on "TQM8260 Bank 0":
> 0x00000000-0x00040000 : "ppcboot"
> 0x00040000-0x00100000 : "kernel"
> 0x00100000-0x00400000 : "initrd"
> 0x00400000-0x00800000 : "jffs"
> ...
>
> Wolfgang Denk
>
> --
> Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
> Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
> There are two ways to write error-free programs. Only the  third  one
> works.
>


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Re: File System on 64-bit-bus-width Flash memory

[Sangmoon Kim]

Hi, all,

Thanks for the helps.
The 64bit buswith MTD support in ftp://ftp.denx.de/pub/LinuxPPC/usr/src/linux-2.4.4-2002-03-21.tar.bz2, which is Wolfgang Denk recommanded, is nice. But... Though it probably works well with MPC8260, it doesn't work with MPC107 which is a memory controller / PCI bridge from motorola. With MPC107 you can't access high 32 bit and low 32 bit separately. Because it doesn't have byte select or word select. Unfortunately my board uses MPC107.
The code in http://www.infradead.org/, which is Allen Curtis recommanded, has a different approach, but with some rack of functionality. First, It did not support probing for 64bit buswidth flash. Second, __raw_readll and __raw_writell, which may be 64bit read write functions, are not exist in kernel.
I changed the infradead code to support 64-bit buswith probing(I referenced the denx code). And made the __raw_writell and __raw_readll using floating load load store operation. I disabled the floating point interrupt to avoid the 'floating point used in kernel' message and re-enabled it. For now I only succeed in probing the chip. Does my approach correct? Is it OK to use floating point operations in kernel or device driver code?
Thank you.
-Sangmoon Kim-

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Re: File System on 64-bit-bus-width Flash memory

[Kenneth Johansson]

Sangmoon Kim wrote:
>
> Hi,
> I want to make a flash file system on a custom MPC755 board with a 64-bit (bus width) flash memory.
> I set CONFIG_MTD_PHYSMAP_BUSWIDTH = 8 at kernel configure, and when it boots the following message appears.
>
> physmap flash device: 400000 at 7c000000
> genprobe_new_chip called with unsupported buswidth 8
> CFI: Found no Physically mapped flash device at location zero
>
> Is it possible to make a flash file system with a flash memory of  64 bit bus width? If possible, what's the method? Please let me know.

You could fix it so it can handle buswith 8 or you could write a mapping
driver that fakes buswidth 4. The simplest is to make the first 32 bits of
the bus one region and the last 32bits another. So if you have 8MiB you get
4MiB only using the first 32 bits followed by 4MiB using the hi 32 bits. This
way the autdetetcion should work ok.


--
Kenneth Johansson
Ericsson AB                       Tel: +46 8 404 71 83
Borgafjordsgatan 9                Fax: +46 8 404 72 72
164 80 Stockholm                  kenneth.johansson@etx.ericsson.se

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