Re: [ECOS] creating serial driver

[venkat ande <venkat_ande at yahoo dot com>]

Hello Andrew sir,

i have already included the <cyg/io/serial.h> in both
the driver code (serial.c) and application code
(serial_app.c). Just now i did one exp. , i commented
the header <cyg/io/serial.h> in application file, but
even after that i am getting the same errors. Where as
i think it must give some error like :symbol
cyg_devtab_entry_t not found or unknown. 

Please suggest, what could be the problem.

And many many thanks for the immediate response sir.

Regards,
VENKAT
--- Andrew Lunn <andrew@lunn.ch> wrote:

> On Fri, Oct 28, 2005 at 02:50:50AM -0700, venkat
> ande wrote:
> > Hello all,
> > 
> > I am having a x86 PC board with running redboot in
> > it.I have to add around 16 serial ports to my x86
> PC
> > board using PCI bus. But as a rookie i am first
> trying
> > to make a driver for  a single port.So what i did,
> i
> > created a driver by using the generic driver of
> 16x5x.
> > But i didn't place it inside the ecos tree. I made
> it
> > as an application in which i used all those macros
> > DEVTAB_ENTRY, SERIAL_CHANNEL_USING_INTERRUPTS,
> > SERIAL_FUNS and then filled the api's with
> reference
> > to the pattern of 16x5x driver.
> > 
> > Then i made one more application to test this
> driver
> > using the ?ecos-2.0\examples\serial.c? (i replaced
> the
> > ?/dev/haldiag? by ?/dev/FT_ser_drv?), FT_ser_drv
> is
> > the string name that i given to my driver.
> > 
> > Now how i am building my last output file (srec).
> > Actually i found this method in ecos discuss
> archives,
> > i am pasting that part here:
> > 
> > -------------------------------------
> > 
> > >Anyway, build your device driver library just
> like an
> > eCos
> > >application, but instead of linking it to eCos
> just
> > use ar to create a
> > >library from the object file. There is nothing
> > special needed, so just
> > >look at normal examples for building libraries.
> > >
> > >To link the libarary to the application and eCos
> just
> > add -lmylib to
> > >the command line when linking. ie nothing special
> or
> > magical needed.
> > >
> > >OK, now the thing to be careful of. When building
> a
> > device driver
> > >within the eCos tree there is normally a cdl
> option: 
> > >
> > >  compile       -library=libextras.a   foobar.c
> > >
> > >ie the object file is put into the library
> > libextras.a not the normal
> > >libtarget.a. At the end of the build process
> > libextras.a is linked to
> > >extras.o and this is then linked to your
> application,
> > not
> > >libextras.a. This is becasue the linker throws
> away
> > any symbols not
> > >referenced in libraries. Normally there is no
> > reference to a device
> > >driver because of the use of linker tables. So if
> the
> > device driver
> > >was inside a library it would not be pulled into
> the
> > final application
> > >executable. 
> > >
> > >For your device driver in your library you cannot
> use
> > the same
> > >trick. So instead your application must reference
> > something in the
> > >device driver so that it is pulled in. Typically
> a
> > device driver has a
> > >DEVTAB_ENTRY, eg
> > >
> > >DEVTAB_ENTRY(ebsa285_serial_io,
> > >            
> > CYGDAT_IO_SERIAL_ARM_EBSA285_SERIAL_NAME,
> > >             0,                     // Does not
> > depend on a lower level interface
> > >             &cyg_io_serial_devio,
> > >             ebsa285_serial_init,
> > >             ebsa285_serial_lookup,     // Serial
> > driver may need initializing
> > >             &ebsa285_serial_channel
> > >    );
> > >
> > >Doing something like:
> > >
> > >  extern cyg_devtab_entry_t *ebsa285_serial_io;
> > >  ebsa285_serial_io = ebsa285_serial_io;
> > >
> > >will probably be enought.
> > -----------------------------------------------
> > 
> > 
> > in my case i am using ?FT_ser_ent? in place of
> > ?ebsa285_serial_io? & FT_SER_DRV_NAME in place of
> > CYGDAT_IO_SERIAL_ARM_EBSA285_SERIAL_NAME.
> > 
> > Where as FT_SER_DRV_NAME is defined as:
> > 
> > #define FT_SER_DRV_NAME	"\"/dev/FT_ser_drv\""
> > 
> > 
> > 
> > and also i have added this in my application file 
> :
> > ------------------------------------------
> >  extern cyg_devtab_entry_t *FT_ser_ent
> >  FT_ser_ent = FT_ser_ent;
> > ------------------------------------------
> 
> 
> > serial_app.c:80: warning: type defaults to `int'
> in
> > declaration of `FT_ser_ent'
> > serial_app.c:80: conflicting types for
> `FT_ser_ent'
> > serial_app.c:79: previous declaration of
> `FT_ser_ent'
> > serial_app.c:80: initializer element is not
> constant
> > serial_app.c:80: warning: data definition has no
> type
> > or storage class
> > make: *** [serial_app.o] Error 1
> 
> You need to fix this. My guess is cyg_devtab_entry_t
> is not known
> because you are missing a header file. Try including
> <cyg/io/serial.h>
> 
>         Andrew
> 



	
		
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