* MPC8260 SCC UART hardware flow control
@ 2006-07-19 15:18 Laurent Pinchart
2006-07-19 18:37 ` Wolfgang Denk
2006-07-20 8:18 ` Mathieu Deschamps
0 siblings, 2 replies; 5+ messages in thread
From: Laurent Pinchart @ 2006-07-19 15:18 UTC (permalink / raw)
To: linuxppc-embedded
Hi everybody,
I was wondering if anyone had implemented hardware flow control support in the
cpm_uart driver. If not, I would appreciate pointers regarding how to do so.
Best regards,
Laurent Pinchart
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: MPC8260 SCC UART hardware flow control
2006-07-19 15:18 MPC8260 SCC UART hardware flow control Laurent Pinchart
@ 2006-07-19 18:37 ` Wolfgang Denk
2006-07-20 14:30 ` Laurent Pinchart
2006-07-20 8:18 ` Mathieu Deschamps
1 sibling, 1 reply; 5+ messages in thread
From: Wolfgang Denk @ 2006-07-19 18:37 UTC (permalink / raw)
To: Laurent Pinchart; +Cc: linuxppc-embedded
In message <200607191718.00328.laurent.pinchart@tbox.biz> you wrote:
>
> I was wondering if anyone had implemented hardware flow control support in the
> cpm_uart driver. If not, I would appreciate pointers regarding how to do so.
You can probably take our 2.4 kernel code as a starting point. But be
aware of the inherent restrictions of the CPM, see
http://www.denx.de/wiki/view/DULG/UseSCCUARTWithHardwareHandshake
[In the end, you might want to configure the handshake signals as
GPIO lines and controll these manually. But then you will have to ask
yourself why you are using a CPM...]
Best regards,
Wolfgang Denk
--
Software Engineering: Embedded and Realtime Systems, Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de
The average woman would rather have beauty than brains, because the
average man can see better than he can think.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: MPC8260 SCC UART hardware flow control
2006-07-19 18:37 ` Wolfgang Denk
@ 2006-07-20 14:30 ` Laurent Pinchart
0 siblings, 0 replies; 5+ messages in thread
From: Laurent Pinchart @ 2006-07-20 14:30 UTC (permalink / raw)
To: Wolfgang Denk; +Cc: linuxppc-embedded
On Wednesday 19 July 2006 20:37, Wolfgang Denk wrote:
> In message <200607191718.00328.laurent.pinchart@tbox.biz> you wrote:
> > I was wondering if anyone had implemented hardware flow control support
> > in the cpm_uart driver. If not, I would appreciate pointers regarding how
> > to do so.
>
> You can probably take our 2.4 kernel code as a starting point. But be
> aware of the inherent restrictions of the CPM, see
> http://www.denx.de/wiki/view/DULG/UseSCCUARTWithHardwareHandshake
I didn't know the CPM implemented hardware flow control as a DTE only. Thanks
for the information. As our hardware connects to DCE devices this shouldn't
be a problem.
> [In the end, you might want to configure the handshake signals as
> GPIO lines and controll these manually. But then you will have to ask
> yourself why you are using a CPM...]
Laurent Pinchart
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: MPC8260 SCC UART hardware flow control
2006-07-19 15:18 MPC8260 SCC UART hardware flow control Laurent Pinchart
2006-07-19 18:37 ` Wolfgang Denk
@ 2006-07-20 8:18 ` Mathieu Deschamps
2006-07-20 14:32 ` Laurent Pinchart
1 sibling, 1 reply; 5+ messages in thread
From: Mathieu Deschamps @ 2006-07-20 8:18 UTC (permalink / raw)
To: Laurent Pinchart; +Cc: linuxppc-embedded
Hi Laurent,
On Wednesday 19 July 2006 17:18, Laurent Pinchart wrote:
> Hi everybody,
>
> I was wondering if anyone had implemented hardware flow control support in
> the cpm_uart driver. If not, I would appreciate pointers regarding how to
> do so.
>
> Best regards,
>
> Laurent Pinchart
>
I had. PQ2 CPM is a dedicated part which handles this aspect for you via
its microcode. This also means you can't play with it the old way and making
your own HHS with a CD/DSR :). Back to seriousness, rather this means you
needn't adding modem signal handling in cpm_uart driver. So don't define
modem_something that's an ancient reliq from the times, I guess, no CPM was
put auxillary.
So how to tell CPM to cope with HHS ? Simple, you "just" have to put SCC's
Dedicated pins the right way which depends on your board type. Remember you
can't do any HHS with SMC. Refer to Dedicated Pins chapter in the litterature
[41.4.2]. Also take a look at SCC GSMR register [20.8] and to SCC UART mode
PSMR register [21-14] to maybe use protocol specificities.
When you'll have your kernel ready, you would do probably something like :
stty -F $port crtscts $SPEED
As Wolfgang said HHS works for DTE-DCE only (roughly but visually you must
have plugs opposite gender on both ends), trying DTE-DTE HHS dialog is bound
to failure despite time spend on it.
Cdy,
Mathieu Deschamps
Com2gether Design Center
Electronic and Embedded Engineering Services
www.com2gether.net
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: MPC8260 SCC UART hardware flow control
2006-07-20 8:18 ` Mathieu Deschamps
@ 2006-07-20 14:32 ` Laurent Pinchart
0 siblings, 0 replies; 5+ messages in thread
From: Laurent Pinchart @ 2006-07-20 14:32 UTC (permalink / raw)
To: Mathieu Deschamps; +Cc: linuxppc-embedded
Hi Mathieu,
> > Hi everybody,
> >
> > I was wondering if anyone had implemented hardware flow control support
> > in the cpm_uart driver. If not, I would appreciate pointers regarding how
> > to do so.
> >
> > Best regards,
> >
> > Laurent Pinchart
>
> I had. PQ2 CPM is a dedicated part which handles this aspect for you via
> its microcode. This also means you can't play with it the old way and
> making your own HHS with a CD/DSR :). Back to seriousness, rather this
> means you needn't adding modem signal handling in cpm_uart driver. So don't
> define modem_something that's an ancient reliq from the times, I guess, no
> CPM was put auxillary.
>
> So how to tell CPM to cope with HHS ? Simple, you "just" have to put SCC's
> Dedicated pins the right way which depends on your board type. Remember you
> can't do any HHS with SMC. Refer to Dedicated Pins chapter in the
> litterature [41.4.2]. Also take a look at SCC GSMR register [20.8] and to
> SCC UART mode PSMR register [21-14] to maybe use protocol specificities.
Thanks.
> When you'll have your kernel ready, you would do probably something like :
> stty -F $port crtscts $SPEED
I suppose I also have to add support for the CRTSCTS flag in set_termios.
> As Wolfgang said HHS works for DTE-DCE only (roughly but visually you must
> have plugs opposite gender on both ends), trying DTE-DTE HHS dialog is
> bound to failure despite time spend on it.
I'll disable hardware flow control if I need DTE-DTE communication.
Thanks for your help.
Laurent Pinchart
^ permalink raw reply [flat|nested] 5+ messages in thread
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2006-07-19 15:18 MPC8260 SCC UART hardware flow control Laurent Pinchart
2006-07-19 18:37 ` Wolfgang Denk
2006-07-20 14:30 ` Laurent Pinchart
2006-07-20 8:18 ` Mathieu Deschamps
2006-07-20 14:32 ` Laurent Pinchart
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