16550 uart without interrupts ?

16550 uart without interrupts ?

[Andreas Schreckenberg]

Hello,

Is there anybody with a serial console uart driver for
ppc systems without using interrupts ?
Is is possible to use any driver in "polling mode" ?
(drivers/char/serial.c or arch/8xx_io/uart.c)

I try to bring up Linux on my custom ppc board
(PPC750, 64M, uart 16550) and my
(selfmade) interrupt controller will not work at this
moment.

But it would be nice to have debug messages on the
serial console. (log_buf is okay but not really the
thing I would like to have)

Can I work with a "polling driver" -> bash input/output ?

I hope that I must not understand the whole driver :-)
(only set the uart I/O range, and set the quartz divider)

bye
Andreas
EMail: ASchreckenberg@dspace.de
--
          Life's not fair. But the root password helps ! :-)
                   http://schrecky.home.pages.de

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

Re: 16550 uart without interrupts ?

[Rabeeh Khoury]

In order to work in polling mode , you have to run a __check__ routine
that runs once, at least, in a constant period of time. The routine
checks if new data has arrived or not and accordingly operates.

I suggest that you hook such a routine to your real time clock interrupt
handler which calls function
'rs_interrupt_single' in file drivers/char/serial.c with the appropriate
parameters.

p.s. the function 'rs_interrupt_single' is suitable in case you are
using one port of the serial controller !

Another option is using the decrementer of the ppc CPU which is usually
also used by the Linux kernel. But you have to find a way how to share
the decrementer with your polling function and the kernel.


Regards,
Rabeeh


Andreas Schreckenberg wrote:

> Hello,
>
> Is there anybody with a serial console uart driver for
> ppc systems without using interrupts ?
> Is is possible to use any driver in "polling mode" ?
> (drivers/char/serial.c or arch/8xx_io/uart.c)
>
> I try to bring up Linux on my custom ppc board
> (PPC750, 64M, uart 16550) and my
> (selfmade) interrupt controller will not work at this
> moment.
>
> But it would be nice to have debug messages on the
> serial console. (log_buf is okay but not really the
> thing I would like to have)
>
> Can I work with a "polling driver" -> bash input/output ?
>
> I hope that I must not understand the whole driver :-)
> (only set the uart I/O range, and set the quartz divider)
>
> bye
> Andreas
> EMail: ASchreckenberg@dspace.de
> --
>           Life's not fair. But the root password helps ! :-)
>                    http://schrecky.home.pages.de
>
>
>
>


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