[dev/cfi] add support for flashes with different bus-vs-device address width

[mizhka]

Summary

The target of this fix is CFI-compatible Macronix MX29GL @ Asus RT-N16 wifi router. This board has 16bit parallel flash and 8bit bus. To enable query mode, we need to use bus_space_write_1 (8bit) to write to location 55x2 (16bit).

This patch adds bus width parameter and way to auto-identify it. It uses this parameter for query mode requests.

It works for me, but I don't have any other CFI devices to test it. I'll appreciate if somebody can test it.

Test Plan

1. Apply patch, build cfi driver
2. Try to probe&attach.

Expected result: driver has been attached.

Tested on Macronix MX29GL chip / ASUS RT-N16.

[ray]

I'm afraid JEDEC CFI standard do not allow simple omit of upper byte(s), you have to try bus and chip data width and get temporary configuration, til required data read from chip.

[mizhka]

• new sc_buswidth parameter to softc
• scan of configuration for new sc_buswidth parameter

[landonf]

It works for me, but I don't have any other CFI devices to test it. I'll appreciate if somebody can test it.

It's still another Broadcom SoC, but I tested against a previously working WGT634U (BCM4716) and saw no regressions.

It'd be nice to get this committed so we can support RT-N16's CFI out of the box.

[adrian]

i'm okay with this, but let's get imp's feedback.

[adrian]

i'm okay with this, but let's get imp's feedback.