- Import the common MII bitbang'ing code from NetBSD and convert drivers to

  take advantage of it instead of duplicating it. This reduces the size of
  the i386 GENERIC kernel by about 4k. The only potential in-tree user left
  unconverted is xe(4), which generally should be changed to use miibus(4)
  instead of implementing PHY handling on its own, as otherwise it makes not
  much sense to add a dependency on miibus(4)/mii_bitbang(4) to xe(4) just
  for the MII bitbang'ing code. The common MII bitbang'ing code also is
  useful in the embedded space for using GPIO pins to implement MII access.
- Based on lessons learnt with dc(4) (see r185750), add bus barriers to the
  MII bitbang read and write functions of the other drivers converted in
  order to ensure the intended ordering. Given that register access via an
  index register as well as register bank/window switching is subject to the
  same problem, also add bus barriers to the respective functions of smc(4),
  tl(4) and xl(4).
- Sprinkle some const.

Thanks to the following testers:
Andrew Bliznak (nge(4)), nwhitehorn@ (bm(4)), yongari@ (sis(4) and ste(4))
Thanks to Hans-Joerg Sirtl for supplying hardware to test stge(4).

Reviewed by:	yongari (subset of drivers)
Obtained from:	NetBSD (partially)

2 files changed, 9 insertions, 6 deletions

diff --git a/sys/conf/NOTES b/sys/conf/NOTES
index ed94494..b80df35 100644
--- a/sys/conf/NOTES
+++ b/sys/conf/NOTES
@@ -1846,13 +1846,15 @@ device		puc
 # MII bus support is required for many PCI Ethernet NICs,
 # namely those which use MII-compliant transceivers or implement
 # transceiver control interfaces that operate like an MII.  Adding
-# "device miibus" to the kernel config pulls in support for
-# the generic miibus API and all of the PHY drivers, including a
-# generic one for PHYs that aren't specifically handled by an
-# individual driver.  Support for specific PHYs may be built by adding
-# "device mii" then adding the appropriate PHY driver.
-device  	miibus		# MII support including all PHYs
+# "device miibus" to the kernel config pulls in support for the generic
+# miibus API, the common support for for bit-bang'ing the MII and all
+# of the PHY drivers, including a generic one for PHYs that aren't
+# specifically handled by an individual driver.  Support for specific
+# PHYs may be built by adding "device mii", "device mii_bitbang" if
+# needed by the NIC driver and then adding the appropriate PHY driver.
 device  	mii		# Minimal MII support
+device  	mii_bitbang	# Common module for bit-bang'ing the MII
+device  	miibus		# MII support w/ bit-bang'ing and all PHYs
 
 device  	acphy		# Altima Communications AC101
 device  	amphy		# AMD AM79c873 / Davicom DM910{1,2}
diff --git a/sys/conf/files b/sys/conf/files
index 90e7b76..e6dfe63 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -1425,6 +1425,7 @@ dev/mii/ip1000phy.c		optional miibus | ip1000phy
 dev/mii/jmphy.c			optional miibus | jmphy
 dev/mii/lxtphy.c		optional miibus | lxtphy
 dev/mii/mii.c			optional miibus | mii
+dev/mii/mii_bitbang.c		optional miibus | mii_bitbang
 dev/mii/mii_physubr.c		optional miibus | mii
 dev/mii/miibus_if.m		optional miibus | mii
 dev/mii/mlphy.c			optional miibus | mlphy