Required for Apple and Microsoft -compatible HID-over-SPI drivers.
Most logic was already implemented in commit 3c08673438
"spibus: extend API: add cs_delay ivar, KEEP_CS and NO_SLEEP flags".
It dissallowed driver sleeps in the interrupt context. This commit
extends this feature to handle ddb/kdb context with following:
- Skip driver locking if SPI functions were called from kdb/ddb.
- Reinitialize controller if kdb/ddb initiated SPI transfer has
interrupted another already running one. Does not work very
reliable yet.
Reviewed by: manu
Differential Revision: https://reviews.freebsd.org/D41247
Also adds fixups and cleanups:
- apply the child's mode/speed
- implement suspend/resume support
- use RF_SHAREABLE interrupts
- use bus_delayed_attach_children since the transfer can use interrupts
- add support for newly added spibus features (cs_delay and flags)
Operation tested on Broadwell (Wildcat Point) MacBookPro12,1.
Attachment also tested on Kaby Lake (Sunrise Point) Pixelbook.
Reviewed by: wulf
MFC after: 1 month
Differential revision: https://reviews.freebsd.org/D29249
