CVS commit: src/sys/dev/i2c

["Jason R Thorpe" <thorpej%netbsd.org@localhost>]

Module Name:    src
Committed By:   thorpej
Date:           Thu Jun  7 13:30:49 UTC 2018

Modified Files:
        src/sys/dev/i2c: i2c.c i2cvar.h

Log Message:
Changes / enhancements to i2c indirect device auto-configuration:

— iic_search() chooses a “probe strategy” based on the
  "i2c-indirect-probe-strategy” property on the “iic” instance.
  Valid values are "smbus-quick-write”, "smbus-receive-byte”, and
  “none”.  If no value is specified, the default is "smbus-quick-write”.

— If the "i2c-indirect-device-whitelist” exists on the “iic” instance,
  iic_search() will first check the driver name in the cfdata_t against
  this list, and only allow the match/probe to move forward if the
  cfdata_t driver name is in the list.  This is primarily to accommodate
  the Intel integrated memory controller neutered-i2c-thing.

— If the cfdata_t specifies a wildcard address, each address of the i2c
  bus will be consulted.  If the cfdata_t contains a nailed-down address,
  then we limit the bus scan to that specific address.

— We explicitly skip reserved / special i2c addresses, such as the
  General-Call address, etc.

— We introduce the notion of a “match quality” for i2c drivers.  From
  lowest-quality to highest-quality: matched by plausible address only,
  matched by plausible address and poking at the bus to see if the
  device looks reasonable, matched by direct-config “compatible” string,
  matched by direct-config “driver name” string.

— If the “match quality” is merely “plausible address only”, then
  iic_search() will use the probe strategy selected above to see if
  a device responds to that address.


To generate a diff of this commit:
cvs rdiff -u -r1.60 -r1.61 src/sys/dev/i2c/i2c.c
cvs rdiff -u -r1.12 -r1.13 src/sys/dev/i2c/i2cvar.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.