sequoia uarts

I have verified that the Sequoia (440EPx) does not have its UARTs properly configured. The attached patch corrects this by setting three bits in SDR0_PFC1 to enable 4-wire mode, and to select cts/rts functionality for the UARTs. Also, I modified the GPIO settings for pins 34-37 to conform to the tables in section 31 of the 440EPx users manual.

Here is a dump of the registers once the patch was made. I've verified that these match the users manual. Also, my Sequoia board works. :-)

=> getidcr e.f 4101
000e.000f-4101 Read 034c100f
=> md.l ef600c00 1
ef600c00: 00000000 ....
=> md.l ef600c04 1
ef600c04: d6000000 ....
=> md.l ef600c08 1
ef600c08: 52180000 R...
=> md.l ef600c10 1
ef600c10: 00000000 ....
=> md.l ef600c40 1
ef600c40: 00000000 ....
=> md.l ef600c38 1
ef600c38: 04010000 ....
=> md.l ef600c30 1
ef600c30: 00405550 . at UP

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We definitely do NOT want any hardware handshake on the serial console. Never.

Best regards,

Wolfgang Denk

DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
I'm frequently appalled by the low regard you Earthmen have for life.
	-- Spock, "The Galileo Seven", stardate 2822.3

Perhaps my comments were not clear. Please let me try again: The schematic for the Sequoia shows two uarts. U-boot leaves the SDR0_PFC1[U0IM] bit cleared to 0, which means that the 440EPx will only have one uart, operating in 8-wire mode. So, U-boot does not set the CPU to the correct mode to enable two uarts. This is independent of whether you want RTS/CTS or not, and as far as I can see, it must be fixed if both uart ports are going to work.

This also applies to the GPIOs. They are not set correctly to connect the uarts to the I/O pins - the wrong functions and polarities are selected. This too is dictated by the schematic. The wires go where they go, and the GPIOs should be configured to match the schematic (or the schematic should be changed to match the software, but we know that isn't going to happen). :-)

The remaining point is the SDR0_PFC1[U0ME] and SDR0_PFC1[U1ME] bits, which determine whether the control signals are RTS/CTS or DCD/DSR. These signals are wired to the DB-9 jacks on pins 7 and 8. According to the RS232 standard, these pins are RTS/CTS, and there is nothing software can do to change their meaning.

So, I believe my patch should be applied as written, so that the software and hardware agree as to function.

That said, /what we choose to do with the lines is up to us/. If we don't want to enable RTS/CTS processing in the drivers, that is fine. We can leave the function disabled. But the hardware registers must be configured to at least match the schematic wiring. Anything else makes no sense.

Steve

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Ack, we don't want hardware handshake enabled in U-Boot. But if I understand this correctly, then this patch from Steven configures the RTS/CTS lines correctly (they are multiplexed with other signals), so that they *can* be used by the OS if needed. It doesn't enable hardware handshake in U-Boot.

Steven please correct me if I am wrong here.

Thanks.

Best regards,
Stefan

=====================================================================
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-0 Fax: +49-8142-66989-80 Email: office at denx.de
=====================================================================

You are correct. The patch simply configures the lines to match the schematic - it does not activate hardware handshake within U-Boot.

Steve

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Could you please send a git formatted patch (git-format-patch and git-send-email are your friends here :)) with a patch description and a signed-off-by line? This makes it easier for me to apply this patch.

Thanks.

Best regards,
Stefan

=====================================================================
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-0 Fax: +49-8142-66989-80 Email: office at denx.de
=====================================================================