Add an interface for cpufreq. The kernel interface lets other drivers

select the CPU frequency level (say for cooling).  The driver interface
allows hardware drivers to announce themselves as capable of adjusting
an individual frequency setting.

sys/kern/cpufreq_if.m

@@ -0,0 +1,92 @@
+#
+# Copyright (c) 2004 Nate Lawson
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+#
+# $FreeBSD$
+#
+
+#include <sys/bus.h>
+
+INTERFACE cpufreq;
+
+HEADER {
+	struct cf_level;
+	struct cf_setting;
+};
+
+# cpufreq interface methods
+
+#
+# Set the current CPU frequency level.
+#
+METHOD int set {
+	device_t		dev;
+	const struct cf_level	*level;
+	int			priority;
+};
+
+#
+# Get the current active level.
+#
+METHOD int get {
+	device_t		dev;
+	struct cf_level		*level;
+};
+
+#
+# Get the current possible levels, based on all drivers.
+#
+METHOD int levels {
+	device_t		dev;
+	struct cf_level		*levels;
+	int			*count;
+};
+
+# Individual frequency driver methods
+
+#
+# Set an individual driver's setting.
+#
+METHOD int drv_set {
+	device_t		dev;
+	const struct cf_setting	*set;
+};
+
+#
+# Get an individual driver's setting.
+#
+METHOD int drv_get {
+	device_t		dev;
+	struct cf_setting	*set;
+};
+
+#
+# Get the settings supported by a driver.
+#
+METHOD int drv_settings {
+	device_t		dev;
+	struct cf_setting	*sets;
+	int			*count;
+	int			*type;
+};