On Wed, Apr 2, 2014 at 2:06 PM, Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx> wrote:
- For the 68[EZ|VZ|SZ]328 you will need to fix up the PLL settings and
do the fixes from Luis Alves at
https://github.com/ljalves/alce68k/commit/4ef1df317c7acb6dfcd0fe9e87be9b4a60b141a4
It would be nice if that work was pushed upstream. Of course, there are
some hurdles to overcome (see Documentation/SubmittingPatches).
If your chip isn't running at 16MHz you have to fix up the serial driver
as it seems to assume a clock of 16MHz for it's baud rate setting.
It's hard to comment without seeing patches, but Kconfig might help here.
At the moment the only specific PLL settings are for PILOT. Everyone
else gets 16MHz.
All I needed to do was take out the bit that enables a second divider
on the 66MHz clock
from the PLL.
--- a/arch/m68k/platform/68000/head.S
+++ b/arch/m68k/platform/68000/head.S
@@ -94,9 +94,9 @@ _start:
#ifdef CONFIG_PILOT
movew #0x2410, 0xfffff200 /* PLLCR */
#else
- movew #0x2400, 0xfffff200 /* PLLCR */
+ movew #0x2493, 0xfffff200 /* PLLCR */
#endif
- movew #0x0123, 0xfffff202 /* PLLFSR */
+ movew #0x0347, 0xfffff202 /* PLLFSR */
moveq #0, %d0
movew #16384, %d0 /* PLL settle wait loop */
_pll_settle:
@@ -230,6 +230,13 @@ _clear_bss:
cmpl %a0, %a1 /* check if at end */
bne _clear_bss
For both the PLL and UART baud rate issue I think a Kconfig setting
for the system clock would work.
For the EZ it should only allow <= 16MHz, for the VZ <= 32MHz and for
the SZ <= 66MHz ...
If it was a choice between 16, 33 or 66 then
drivers/tty/serial/68328serial.c could compile in the right table.
At the moment it assumes the VZ is running at 33MHz but the PLL
settings configure it for 16MHz.
If I get time I'll try to put together a patch set that fixes the
various issues, add a defconfig for this dev kit etc.
I'd assume that GCC developers don't have the hardware. But I've found
that they are generally inclined to help. You'd need to build and test
your patches though. Crosstool-NG or OpenEmbedded can help with this.
Here is the bug: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53386
They say to use the target m68k-uclinuxoldabi but that was deprecated
in GCC 4.6 so it doesn't exist any more.
I'm happy with GCC 4.5 for now.
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