Major changes to the generic device framework for FreeBSD/alpha:

* Eliminate bus_t and make it possible for all devices to have
  attached children.

* Support dynamically extendable interfaces for drivers to replace
  both the function pointers in driver_t and bus_ops_t (which has been
  removed entirely.  Two system defined interfaces have been defined,
  'device' which is mandatory for all devices and 'bus' which is
  recommended for all devices which support attached children.

* In addition, the alpha port defines two simple interfaces 'clock'
  for attaching various real time clocks to the system and 'mcclock'
  for the many different variations of mc146818 clocks which can be
  attached to different alpha platforms.  This eliminates two more
  function pointer tables in favour of the generic method dispatch
  system provided by the device framework.

Future device interfaces may include:

* cdev and bdev interfaces for devfs to use in replacement for specfs
  and the fixed interfaces bdevsw and cdevsw.

* scsi interface to replace struct scsi_adapter (not sure how this
  works in CAM but I imagine there is something similar there).

* various tailored interfaces for different bus types such as pci,
  isa, pccard etc.

1 files changed, 38 insertions, 5 deletions

diff --git a/sys/sys/bus_private.h b/sys/sys/bus_private.h
index 5a9fba9..15d7620 100644
--- a/sys/sys/bus_private.h
+++ b/sys/sys/bus_private.h
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 1997 Doug Rabson
+ * Copyright (c) 1997,1998 Doug Rabson
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -23,7 +23,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id$
+ *	$Id: bus_private.h,v 1.1 1998/06/10 10:57:23 dfr Exp $
  */
 
 #ifndef _SYS_BUS_PRIVATE_H_
@@ -36,6 +36,7 @@
  */
 typedef TAILQ_HEAD(devclass_list, devclass) devclass_list_t;
 typedef TAILQ_HEAD(driver_list, driver) driver_list_t;
+typedef TAILQ_HEAD(device_list, device) device_list_t;
 
 struct devclass {
     TAILQ_ENTRY(devclass) link;
@@ -47,11 +48,40 @@ struct devclass {
 };
 
 /*
+ * Compiled device methods.
+ */
+struct device_ops {
+    int maxoffset;
+    devop_t methods[1];
+};
+
+/*
+ * Helpers for device method wrappers.
+ */
+#define DEVOPDESC(OP)	(&OP##_##desc)
+
+#define DEVOPOFF(DEV, OP)				\
+	((DEVOPDESC(OP)->offset >= DEV->ops->maxoffset	\
+	  || !DEV->ops->methods[DEVOPDESC(OP)->offset])	\
+	 ? 0 : DEVOPDESC(OP)->offset)
+
+#define DEVOPMETH(DEV, OP) (DEV->ops->methods[DEVOPOFF(DEV, OP)])
+
+/*
  * Implementation of device.
  */
 struct device {
-    TAILQ_ENTRY(device)	link;	/* list of devices on a bus */
-    bus_t		parent;
+    /*
+     * Device hierarchy.
+     */
+    TAILQ_ENTRY(device)	link;	/* list of devices in parent */
+    device_t		parent;
+    device_list_t	children; /* list of subordinate devices */
+
+    /*
+     * Details of this device.
+     */
+    device_ops_t	ops;
     driver_t		*driver;
     devclass_t		devclass; /* device class which we are in */
     int			unit;
@@ -66,6 +96,9 @@ struct device {
     void		*softc;
 };
 
-
+struct device_op_desc {
+    unsigned int	offset;	/* offset in driver ops */
+    const char*		name;	/* unique name (for registration) */
+};
 
 #endif /* !_SYS_BUS_PRIVATE_H_ */