Add initial support for Alpine V2

[mst_semihalf.com]

Summary

• Add compatible string in uart 8250 driver
• Add uart 8250 device to GENERIC arm64 configuration
• Use /soc/uart0 as system console if 'serial0' was not found
• Get memory ranges from FDT if no EFI API is available

[andrew]

sys/arm64/arm64/machdep.c

857

if (efihdr != NULL)

sys/dev/uart/uart_cpu_fdt.c

171–172

This looks too much like a hack. The dtb should provide a chosen node, and we shouldn't guess too much which uart to use if it's missing.

[wma]

I suggest splitting this change into separate patches, i.e. FDT, UART compat string etc. I don't think this patch contain anything specific to Alpine-v2.

Agree with Andrew, /soc/uart0 is not something we can expect to be in other DTSes. Is there anything we can do with DTS? Like ask A. to provide 'chosen' link or do a fixup in uboot?

[mst_semihalf.com]

In D5395#114928, @wma wrote:

I suggest splitting this change into separate patches, i.e. FDT, UART compat string etc. I don't think this patch contain anything specific to Alpine-v2.

Agree with Andrew, /soc/uart0 is not something we can expect to be in other DTSes. Is there anything we can do with DTS? Like ask A. to provide 'chosen' link or do a fixup in uboot?

I will split it into three patches then. I suppose we can ask them to add the chosen node to the DTS as there will be changes needed anyway to fix other boot issues.

[mst_semihalf.com]

I have split this patch into three separate ones: D5404, D5406 and D5408.