Add a new device control utility for new-bus devices called devctl. This

allows the user to request administrative changes to individual devices
such as attach or detaching drivers or disabling and re-enabling devices.
- Add a new /dev/devctl2 character device which uses ioctls for device
  requests.  The ioctls use a common 'struct devreq' which is somewhat
  similar to 'struct ifreq'.
- The ioctls identify the device to operate on via a string.  This
  string can either by the device's name, or it can be a bus-specific
  address.  (For unattached devices, a bus address is the only way to
  locate a device.)  Bus drivers register an eventhandler to claim
  unrecognized device names that the driver recognizes as a valid address.
  Two buses currently support addresses: ACPI recognizes any device
  in the ACPI namespace via its full path starting with "\" and
  the PCI bus driver recognizes an address specification of
  'pci[<domain>:]<bus>:<slot>:<func>' (identical to the PCI selector
  strings supported by pciconf).
- To make it easier to cut and paste, change the PnP location string
  in the PCI bus driver to output a full PCI selector string rather
  than 'slot=<slot> function=<func>'.
- Add a devctl(3) interface in libdevctl which provides a wrapper around
  the ioctls and is the preferred interface for other userland code.
- Add a devctl(8) program which is a simple wrapper around the requests
  supported by devctl(3).
- Add a device_is_suspended() function to check DF_SUSPENDED.
- Add a resource_unset_value() function that can be used to remove a
  hint from the kernel environment.  This is used to clear a
  hint.<driver>.<unit>.disabled hint when re-enabling a boot-time
  disabled device.

Reviewed by:	imp (parts)
Requested by:	imp (changing PCI location string)
Relnotes:	yes

1 files changed, 28 insertions, 0 deletions

diff --git a/sys/kern/subr_hints.c b/sys/kern/subr_hints.c
index 25838ee..00cfbf1 100644
--- a/sys/kern/subr_hints.c
+++ b/sys/kern/subr_hints.c
@@ -461,3 +461,31 @@ resource_disabled(const char *name, int unit)
 	       return (0);
 	return (value);
 }
+
+/*
+ * Clear a value associated with a device by removing it from
+ * the kernel environment.  This only removes a hint for an
+ * exact unit.
+ */
+int
+resource_unset_value(const char *name, int unit, const char *resname)
+{
+	char varname[128];
+	const char *retname, *retvalue;
+	int error, line;
+	size_t len;
+
+	line = 0;
+	error = resource_find(&line, NULL, name, &unit, resname, NULL,
+	    &retname, NULL, NULL, NULL, NULL, &retvalue);
+	if (error)
+		return (error);
+
+	retname -= strlen("hint.");
+	len = retvalue - retname - 1;
+	if (len > sizeof(varname) - 1)
+		return (ENAMETOOLONG);
+	memcpy(varname, retname, len);
+	varname[len] = '\0';
+	return (kern_unsetenv(varname));
+}