UCC UART

[Chuck Meade]

>> Hi Gary,
>>
>> According to the errata, it looks like the MPC8358 is subject to
>> erratum QE_UART6.  You'll need to use soft UART mode and load the
>> microcode patch.  Once that is done you will also need to use two
>> different BRG's, one for tx and one for rx, since the soft UART mode
>> microcode patch requires them to be set to different rates (I believe
>> Rx is 16*baud under soft UART mode, and Tx is 1*baud).
> 
> As I feared!  Can you tell me where/how to get the microcode patch?
> 
>> Also, I don't know if it matters or not, but you should change your
>> dts entry "serial at 4000" to "serial at 2200", just like you recently changed
>> your "reg =" to 0x2200.
> 
> I did that as soon as I sent this and saw the glaring inconsistency :-)
> 
> Thanks

Sure.  Go to opensource.freescale.com/firmware and download (for your MPC8358)
the 8360 soft UART mode microcode patch.  You will need to know if your CPU
is a 2.0 or 2.1 silicon, since there is a different microcode patch for each.

Then in the kernel config I believe I included CONFIG_FW_LOADER and CONFIG_HOTPLUG
(one of those may have autoselected the other).

Make sure in your ucc_uart.c driver that soft uart mode is enabled.

At boot time, the driver will kick off a 10 second timer that will expect
the microcode patch to be loaded before the end of that 10 secs.

Very early in my boot sequence, I have a startup script send the microcode patch
file to the driver through the firmware-loading sysfs entry.  But you need to
be aware that the UCC number in the sysfs path will be offset by one.  Since you
are using UCC3, you should use a '2' in the path as shown below.  This sequence
worked for me (I changed the number for you to '2' in my command sequence, since
I use a different UCC):

  echo 1 > /sys/class/firmware/fsl-ucc-uart2/loading
  cat /root/fsl_qe_ucode_uart_8360_21.bin > /sys/class/firmware/fsl-ucc-uart2/data
  echo 0 > /sys/class/firmware/fsl-ucc-uart2/loading

Note that the above presupposes you are using the file for silicon 2.1.
Also presupposes that you have put the microcode under your rootfs /root directory.

Chuck Meade
chuck at ThePTRGroup.com