[coreboot] F2M85 serial port not working (was: Re: AMD AGESA board removals)

[Michael Büchler]

Hi Denis,

On Wed, 2019-12-11 at 01:35 +0100, Denis 'GNUtoo' Carikli wrote:
> As the serial port doesn't work (it needs to be fixed in Coreboot), I
> need to look for an alternative way to get the logs (I'll probably
> try
> finding the EHCI debug port or setting up a PCIe serial port card).

I'm using the F2M85 port as a basis for trying to port to ASUS M5A97.
Serial console works, at least until AmdInitEarly, after these changes:

- make sure the LPC controller is enabled, see hudson_lpc_port80().
Until 657d68bddc030e38bc19eb4eef07f59b5e5258e4 this was called in
f2a85-m/romstage.c

- don't set HUDSON_LEGACY_FREE (default y), otherwise
FchInitResetLpcProgram() will clear bit 6 on the LPC controller's
PCI_Reg 44h that enables serial port decoding.

I also changed the second part of sbxxx_enable_48mhzout() a bit, but
that might be specific to my board:

+       /* [1:0] clk1_sel = b10 --> 48 MHz
+        * [2]   clk1_OutputEnB = b1 --> 14M_25M_48M_OSC output
+        *                           enabled */
        reg32 = SB_MMIO_MISC32(0x40);
-       reg32 &= ~0x80u;
+       reg32 |= (1 << 1);
+       reg32 &= ~((1 << 0) | (1 << 2));
        SB_MMIO_MISC32(0x40) = reg32;

I Hope this helps.

Michael