MPC834x global timers question

I know this isn't the right forum for this but I can't seem to find a 
generic PPC mailing list.

I'm trying to get a global timer going on an MPC834x, and the way I learn 
is to just play with HW, so I've got an Abatron BDI2K hooked up to my 
processor so I can just manipulate registers without having to deal with 
writing code.  However, I seem to be unable to modify certain registers in 
the global timers with this set up and I don't understand why. 
Specifically, if a register has a bit that's a '1' following a reset, I 
can't change that bit to a '0'.  This is happening with the Global Timers 
Reference Registers (GTRFR1 - 4) and the Global Timers Prescale Registers 
(GTPSR1 - 4).  The reset state of the GTRFRs is 0xFFFF and I can't change 
it to any other value.  The reset state of the GTPSRs is 0x3 and I can't 
clear the 2 LSB.  I can change any other bits in the prescale registers, 
but not the two which are a '1' at reset.

Has anyone else seen this behavior?

Bruce

Never mind, I answered my own question.  Sorry for the noise.

Bruce

linuxppc-embedded-bounces+brucle=selinc.com@ozlabs.org wrote on 02/23/2007 
05:20:14 PM:

I know this isn't the right forum for this but I can't seem to find a 
generic PPC mailing list.

I'm trying to get a global timer going on an MPC834x, and the way I 

learn 

is to just play with HW, so I've got an Abatron BDI2K hooked up to my 
processor so I can just manipulate registers without having to deal with 

writing code.  However, I seem to be unable to modify certain registers 

in 

the global timers with this set up and I don't understand why. 
Specifically, if a register has a bit that's a '1' following a reset, I 
can't change that bit to a '0'.  This is happening with the Global 

Timers 

Reference Registers (GTRFR1 - 4) and the Global Timers Prescale 

Registers 

(GTPSR1 - 4).  The reset state of the GTRFRs is 0xFFFF and I can't 

change 

it to any other value.  The reset state of the GTPSRs is 0x3 and I can't 

clear the 2 LSB.  I can change any other bits in the prescale registers, 

but not the two which are a '1' at reset.

Has anyone else seen this behavior?

Bruce
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Linuxppc-embedded@ozlabs.org
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Bruce,

--- Bruce_Leonard@selinc.com wrote:

I know this isn't the right forum for this but I
can't seem to find a 
generic PPC mailing list.

I'm trying to get a global timer going on an
MPC834x, and the way I learn 
is to just play with HW, so I've got an Abatron
BDI2K hooked up to my 
processor so I can just manipulate registers without
having to deal with 
writing code.  However, I seem to be unable to
modify certain registers in 
the global timers with this set up and I don't
understand why. 
Specifically, if a register has a bit that's a '1'
following a reset, I 
can't change that bit to a '0'.  This is happening
with the Global Timers 
Reference Registers (GTRFR1 - 4) and the Global
Timers Prescale Registers 
(GTPSR1 - 4).  The reset state of the GTRFRs is
0xFFFF and I can't change 
it to any other value.  The reset state of the
GTPSRs is 0x3 and I can't 
clear the 2 LSB.  I can change any other bits in the
prescale registers, 
but not the two which are a '1' at reset.

There's a sequence that needs to be followed.  You
need to enable the timer first, then set the mode,
then set the prescaler.  I've attached some expect
code for U-boot that generates a 1Hz output from timer
3 on an MCP8349.  It's not quite what you have, but
hopefully close enough for you to figure it out.  I
also have a simple char driver for Linux if you need
it later on.

COMMENT "Set SICLR so that GPIO1_8 becomes TOUT3"
send "mm.w e0000114\r"
expect $mmPrompt
send "8001\r"
expect $mmPrompt
send "q\r"
expect $mainPrompt

COMMENT "Enable timer 3"
send "mm.b e0000504\r"
expect $mmPrompt
send "01\r"
expect $mmPrompt
send "q\r"
expect $mainPrompt

COMMENT "Set mode register"
send "mm.w e0000520\r"
expect $mmPrompt
send "ff0c\r"
expect $mmPrompt
send "q\r"

COMMENT "Set frequency to 1Hz"
send "mm.w e0000524\r"
expect $mmPrompt
send "1f77\r"
expect $mmPrompt
send "q\r"
expect $mainPrompt

Hope this helps
regards,
Ben

I am having a little trouble with kgdb in an 8541 kernel.=20

The kernel is compiled with CONFIG_DEBUG_KERNEL, CONFIG_KGDB, =
CONFIG_KGDB_TTYS1 all defined and I can boot it to the point where it is =
waiting for a gdb connection and it does make a connection. I have =
kernel command line that contains "kgdb=3DttyS1,115200,halt kgdbwait" in =
it and this appears to be working fine and the output looks like this.

MMU:enterJCSSU'=EB=81init
MMU:mapin
MMU:setio
MMU:exit
begin start_kernel
setup_arch: enter
setup_arch: kgdb breakpoint

At this point, from the cross-compiled gdb on a host, if I invoke gdb =
with vmlinux as an argument, the PC is zero.

$ ppc-gdb vmlinux

(gdb)set remotebaud 115200

(gdb)target remote /dev/ttyUSB0

(gdb)0x00000000 in ?? ()

If I invoke the cross-compiled gdb without vmlinux as an argument, I get =
a better looking pc, like this

$ ppc-gdb=20

(gdb)set remotebaud 115200

(gdb)target remote /dev/ttyUSB0

(gdb)0xc00071f4 in ?? ()

But in neither case can I 'step' or 'next' as gdb merely replies

Cannot find bounds of current function.

Can someone offer a spot of advice to this despicable condition?

Charles

p.s. I apologize if this comes out html as I am using the companies =
webmail interface from home.

=20

=20

In our design for an 8541 board, we are going to be using FCC1 & FCC2 in =
addition to the FAST controller.
=20
I have been looking through the Linux-2.6.17.11 source we are using and =
although I can find some references to MPC85xx_CPM_FCC1, I cannot quite =
identify the driver used with the 85xx in Linux.
=20
Can someone help me determine the name of the appropriate driver for the =
two FCC sections of the 8541 please?
=20
Charles
=20
=20

Hi Charles

The kernel is compiled with CONFIG_DEBUG_KERNEL, CONFIG_KGDB,
CONFIG_KGDB_TTYS1 all defined and I can boot it to the point
where it is waiting for a gdb connection and it does make a
connection. I have kernel command line that contains
"kgdb=3DttyS1,115200,halt kgdbwait" in it and this appears to
be working fine and the output looks like this.
=20
MMU:enterJCSSU'=EB=81init
MMU:mapin
MMU:setio
MMU:exit
begin start_kernel
setup_arch: enter
setup_arch: kgdb breakpoint
=20
At this point, from the cross-compiled gdb on a host, if I
invoke gdb with vmlinux as an argument, the PC is zero.
=20
$ ppc-gdb vmlinux
=20
(gdb)set remotebaud 115200
=20

At this point, try setting the architecture as below (you can
show the current architecture first, to check that it is
wrongly set to "e500", which doesn't work properly)

(gdb) show architecture
The target architecture is set automatically (currently powerpc:e500)

(gdb) set architecture powerpc:common
The target architecture is assumed to be powerpc:common

(gdb)target remote /dev/ttyUSB0
...

More explanation can be found here:
http://www.ultsol.com/faq_p311.htm
[I would prefer to reference an explanation on this
mailing list, but I did not find one.]

I hope this solves your problem.

Clive

On 25 =CE=A6=CE=B5=CE=B2 2007, at 12:19 =CE=A0=CE=9C, Charles Krinke =
wrote:

In our design for an 8541 board, we are going to be using FCC1 & =20
FCC2 in addition to the FAST controller.

I have been looking through the Linux-2.6.17.11 source we are using =20=

and although I can find some references to MPC85xx_CPM_FCC1, I =20
cannot quite identify the driver used with the 85xx in Linux.

Can someone help me determine the name of the appropriate driver =20
for the two FCC sections of the 8541 please?

Charles

Hi Charles,

There's FCC support in the fs_enet driver, but I'm afraid it's not being
ported to the 85xx yet I'm afraid. The only supported family for the =20
fcc's is 82xx.

It shouldn't be very hard to add this, and I'd be glad to help with =20
some pointers.

Regards

-- Pantelis