ppc_ide_md.insw

ppc_ide_md.insw

[Adrian Cox]

Do ppc_ide_md.insw and .outsw actually do anything in recent 2.2
kernels? My grepping has left me unclear.

I need to implement a driver for a compact flash interface which can't
take 16-bit cycles. Do I need to invent my own mechanism to replace the
insw and outsw operations in drivers/block/ide.c?

- Adrian Cox, AG Electronics

** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/

Re: ppc_ide_md.insw

[Neil Russell]

They are used by macros in include/asm-ppc/ide.h called "insw" and "outsw".
I know they are called because I have traced them.  You can just fix the
versions in the arch/ppc/kernel directory to do what you want.

Normally, there is logic to convert 16-bit accesses from a CPU into a pair
of 8-bit accesses for IDE (a hangover from the ISA bus).  Our hardware does
this but I'm not entirely convinced that this is necessary.  Anyhow, if you
are using one of the PPCs in the 8xx family, or the 8260 you can define a
chip select line for IDE that has an 8-bit bus width, obviating any need
to change software.


Neil


On Thu, Oct 19, 2000 at 01:44:21PM +0100, Adrian Cox wrote:
> Do ppc_ide_md.insw and .outsw actually do anything in recent 2.2
> kernels? My grepping has left me unclear.
>
> I need to implement a driver for a compact flash interface which can't
> take 16-bit cycles. Do I need to invent my own mechanism to replace the
> insw and outsw operations in drivers/block/ide.c?
>
> - Adrian Cox, AG Electronics
>

--
Neil Russell <caret@c-side.com>

** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/

Re: ppc_ide_md.insw

[Adrian Cox]

Neil Russell wrote:

> They are used by macros in include/asm-ppc/ide.h called "insw" and "outsw".
> I know they are called because I have traced them.  You can just fix the
> versions in the arch/ppc/kernel directory to do what you want.

I'm using the 2.2 bitkeeper kernel, and there are no macros in
include/asm-ppc/ide.h:
~/linux-bk/linuxppc_2_2> grep insw include/asm-ppc/*
grep: include/asm-ppc/SCCS: Is a directory
include/asm-ppc/ide.h:        void        (*insw)(ide_ioreg_t port, void
*buf, int ns);
include/asm-ppc/ide.h:void ide_insw(ide_ioreg_t port, void *buf, int
ns);
include/asm-ppc/io.h:#define insw(port, buf, ns)	_insw_ns((unsigned
short *)((port)+_IO_BASE), (buf), (ns))
include/asm-ppc/io.h:extern void _insw(volatile unsigned short *port,
void *buf, int ns);
include/asm-ppc/io.h:#define insw_ns(port, buf, ns)	_insw_ns((unsigned
short *)((port)+_IO_BASE), (buf), (ns))
include/asm-ppc/io.h:extern void _insw_ns(volatile unsigned short *port,
void *buf, int ns);

> Normally, there is logic to convert 16-bit accesses from a CPU into a pair
> of 8-bit accesses for IDE (a hangover from the ISA bus).  Our hardware does
> this but I'm not entirely convinced that this is necessary.  Anyhow, if you
> are using one of the PPCs in the 8xx family, or the 8260 you can define a
> chip select line for IDE that has an 8-bit bus width, obviating any need
> to change software.

I've got a CF card on PortX of an MPC107. The MPC107 breaks the 16-bit
read into two 8-bit reads, in the wrong order. This is not a simple
endianness problem, as this ordering doesn't correctly advance the
internal counter of the CF card.

- Adrian Cox, AG Electronics

** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/