Hi Tim,
On Wed, Oct 7, 2015 at 11:26 PM, Timothy Scott tescott425@gmail.com wrote:
Bin,
Thanks for the response. I've got things working with v2015.04, but it took some tweaking. Here's what I learned:
- PCI is initialized AFTER the code was attempting to configure hsuart0.
Since hsuart0 is on the PCI bus, the various registers being read were coming up 0xFFFF and therefore hsuart0 access was invalid.
Yes, in v2015.04, Intel Crown Bay codes did this by defining CONFIG_SYS_EARLY_PCI_INIT and calling the PCI enumeration in arch_cpu_init() manually. With DM conversion on the latest u-boot/master branch, this is not needed as the enumeration will be triggered as needed.
- I'm swapping between PCU_UART (legac y) and SIO_UART at run-time, while
using the ns16550 driver in both instances. The code that underlies ns16550_writeb() and ns16550_readb() expects things to be configured at compile time via CONFIG options instead of something you can jack with at run-time.
This can be enhanced by converting the ns16550 CONFIG options to a device tree bindings, however I don't know if there is any plan to do this. My only concern of doing it via device tree is that some performance degradation might be observed.
My workarounds:
- created hsuart_init() in serial-uclass.c, patterned off of
serial_find_console_or_panic(). This references a unique chosen option I named "hsuart-path" and loads up hsuart device for me. I do this to get the hsuart0 probed and loaded. (If there's a better way to force a device probe, please let me know.)
- created initr_hsuart_serial() in board_r.c, and invoked this via the
init_sequence_r[] table, after initr_pci.
- updated ns16550.c's ns16550_platdata with a "mem_map" parameter. I added
a "mem-map" parm to the hsuart DTS entry, and load this value in via ns16550_serial_ofdata_to_platdata. This is then referenced in ns16550_writeb() and ns16550_readb() to perform a memory mapped access, instead of whatever the CONFIG options have defined. In my case, CONFIG options result in a port mapped access.
All this is pretty hackish but works for my purposes.
Thanks again, --tim
Regards, Bin