MPC82xx ADS SCC ports initialisation

Laurent Pinchart laurent.pinchart at
Wed Jul 11 00:19:51 EST 2007

Hi everybody,

while checking the availability of MPC8260 support in ARCH=powerpc, I ran 
across a possible issue in SCC ports initialisation for the MPC82xx ADS 

init_scc1_uart_ioports and init_scc4_uart_ioports in 
arch/powerpc/platforms/mpc82xx/mpx82xx_ads.c use the following code to 
configure the SCC clocks:

clrbits32(&immap->im_cpmux.cmx_scr, (0x00000007 << (4 - data->clk_tx)));
clrbits32(&immap->im_cpmux.cmx_scr, (0x00000038 << (4 - data->clk_rx)));
          ((data->clk_tx - 1) << (4 - data->clk_tx)));
          ((data->clk_rx - 1) << (4 - data->clk_rx)));

The shift right-hand operand doesn't seem to be correct. Could anyone confirm 
this ? If my assumption is right, could anyone tell me if the MPC82xx 
processors are actually supported by the powerpc architecture, or if the 
MPC82xx ADS code is just a non-functional work in progress.

I also noticed that U-Boot doesn't have flatten device tree support for the 
MPC82xx family. There seem to be still a lot of work to do to support the 
MPC82xx in the powerpc tree, and the effort is much bigger than just porting 
a board from ppc to powerpc.

Laurent Pinchart

More information about the Linuxppc-embedded mailing list