Create an interface for drivers to enable or disable their clocks as listed

in the clocks=<...> properties of their FDT data.  The clock properties
consist of 2-cell tuples, each containing a clock device node reference and
a clock number.  A clock device driver can register itself as providing
this interface, then other drivers can turn the FDT clock node reference
into the corresponding device_t so that they can use the interface to query
and manipulate their clocks.

This provides convenience functions to enable or disable all the clocks
listed in the properties for a device, so most drivers will be able to
manage their clocks with a single call to fdt_clock_enable_all(dev).

4 files changed, 298 insertions, 0 deletions

diff --git a/sys/conf/files b/sys/conf/files
index ecae527..a2c1c69 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -1376,6 +1376,8 @@ dev/fatm/if_fatm.c		optional fatm pci
 dev/fb/fbd.c			optional fbd | vt
 dev/fb/fb_if.m			standard
 dev/fb/splash.c			optional sc splash
+dev/fdt/fdt_clock.c		optional fdt
+dev/fdt/fdt_clock_if.m		optional fdt
 dev/fdt/fdt_common.c		optional fdt
 dev/fdt/fdt_slicer.c		optional fdt cfi | fdt nand
 dev/fdt/fdt_static_dtb.S	optional fdt fdt_dtb_static \
diff --git a/sys/dev/fdt/fdt_clock.c b/sys/dev/fdt/fdt_clock.c
new file mode 100644
index 0000000..8c970bc
--- /dev/null
+++ b/sys/dev/fdt/fdt_clock.c
@@ -0,0 +1,160 @@
+/*-
+ * Copyright (c) 2014 Ian Lepore <ian@freebsd.org>
+ * 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/cdefs.h>
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/queue.h>
+
+#include <dev/ofw/ofw_bus.h>
+#include <dev/ofw/ofw_bus_subr.h>
+
+#include "fdt_clock_if.h"
+#include <dev/fdt/fdt_clock.h>
+
+/*
+ * Loop through all the tuples in the clocks= property for a device, enabling or
+ * disabling each clock.
+ *
+ * Be liberal about errors for now: warn about a failure to enable but keep
+ * trying with any other clocks in the list.  Return ENXIO if any errors were
+ * found, and let the caller decide whether the problem is fatal.
+ */
+static int
+enable_disable_all(device_t consumer, boolean_t enable)
+{
+	phandle_t cnode;
+	device_t clockdev;
+	int clocknum, err, i, ncells;
+	uint32_t *clks;
+	boolean_t anyerrors;
+
+	cnode = ofw_bus_get_node(consumer);
+	ncells = OF_getencprop_alloc(cnode, "clocks", sizeof(*clks),
+	    (void **)&clks);
+	if (enable && ncells < 2) {
+		device_printf(consumer, "Warning: No clocks specified in fdt "
+		    "data; device may not function.");
+		return (ENXIO);
+	}
+	anyerrors = false;
+	for (i = 0; i < ncells; i += 2) {
+		clockdev = OF_device_from_xref(clks[i]);
+		clocknum = clks[i + 1];
+		if (clockdev == NULL) {
+			if (enable)
+				device_printf(consumer, "Warning: can not find "
+				    "driver for clock number %u; device may not "
+				    "function\n", clocknum);
+			anyerrors = true;
+			continue;
+		}
+		if (enable)
+			err = FDT_CLOCK_ENABLE(clockdev, clocknum);
+		else
+			err = FDT_CLOCK_DISABLE(clockdev, clocknum);
+		if (err != 0) {
+			if (enable)
+				device_printf(consumer, "Warning: failed to "
+				    "enable clock number %u; device may not "
+				    "function\n", clocknum);
+			anyerrors = true;
+		}
+	}
+	free(clks, M_OFWPROP);
+	return (anyerrors ? ENXIO : 0);
+}
+
+int
+fdt_clock_get_info(device_t consumer, int n, struct fdt_clock_info *info)
+{
+	phandle_t cnode;
+	device_t clockdev;
+	int clocknum, err, ncells;
+	uint32_t *clks;
+
+	cnode = ofw_bus_get_node(consumer);
+	ncells = OF_getencprop_alloc(cnode, "clocks", sizeof(*clks),
+	    (void **)&clks);
+	if (ncells <= 0)
+		return (ENXIO);
+	n *= 2;
+	if (ncells <= n)
+		err = ENXIO;
+	else {
+		clockdev = OF_device_from_xref(clks[n]);
+		if (clockdev == NULL)
+			err = ENXIO;
+		else  {
+			/*
+			 * Make struct contents minimally valid, then call
+			 * provider to fill in what it knows (provider can
+			 * override anything it wants to).
+			 */
+			clocknum = clks[n + 1];
+			memset(info, 0, sizeof(*info));
+			info->provider = clockdev;
+			info->index = clocknum;
+			info->name = "";
+			err = FDT_CLOCK_GET_INFO(clockdev, clocknum, info);
+		}
+	}
+	free(clks, M_OFWPROP);
+	return (err);
+}
+
+int
+fdt_clock_enable_all(device_t consumer)
+{
+
+	return (enable_disable_all(consumer, true));
+}
+
+int
+fdt_clock_disable_all(device_t consumer)
+{
+
+	return (enable_disable_all(consumer, false));
+}
+
+void
+fdt_clock_register_provider(device_t provider)
+{
+
+	OF_device_register_xref(OF_xref_from_node(provider), provider);
+}
+
+void
+fdt_clock_unregister_provider(device_t provider)
+{
+
+	OF_device_register_xref(OF_xref_from_node(provider), NULL);
+}
+
diff --git a/sys/dev/fdt/fdt_clock.h b/sys/dev/fdt/fdt_clock.h
new file mode 100644
index 0000000..1d904cf
--- /dev/null
+++ b/sys/dev/fdt/fdt_clock.h
@@ -0,0 +1,55 @@
+/*-
+ * Copyright (c) 2014 Ian Lepore <ian@freebsd.org>
+ * 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 ``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 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef DEV_FDT_CLOCK_H
+#define DEV_FDT_CLOCK_H
+
+#include "fdt_clock_if.h"
+
+/*
+ * Get info about the Nth clock listed in consumer's "clocks" property.
+ *
+ * Returns 0 on success, ENXIO if clock #n not found.
+ */
+int fdt_clock_get_info(device_t consumer, int n, struct fdt_clock_info *info);
+
+/*
+ * Look up "clocks" property in consumer's fdt data and enable or disable all
+ * configured clocks.
+ */
+int fdt_clock_enable_all(device_t consumer);
+int fdt_clock_disable_all(device_t consumer);
+
+/*
+ * [Un]register the given device instance as a driver that implements the
+ * fdt_clock interface.
+ */
+void fdt_clock_register_provider(device_t provider);
+void fdt_clock_unregister_provider(device_t provider);
+
+#endif /* DEV_FDT_CLOCK_H */
+
diff --git a/sys/dev/fdt/fdt_clock_if.m b/sys/dev/fdt/fdt_clock_if.m
new file mode 100644
index 0000000..68e4e49
--- /dev/null
+++ b/sys/dev/fdt/fdt_clock_if.m
@@ -0,0 +1,81 @@
+#-
+# Copyright (c) 2014 Ian Lepore
+# 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/types.h>
+
+#
+# This is the interface that fdt_clock drivers provide to other drivers.
+# In this context, clock refers to a clock signal provided to some other
+# hardware component within the system.  They are most often found within
+# embedded processors that have on-chip IO controllers.
+#
+
+INTERFACE fdt_clock;
+
+HEADER {
+
+	enum {
+		FDT_CIFLAG_RUNNING =	0x01,
+	};
+
+	struct fdt_clock_info {
+		device_t	provider;
+		uint32_t	index;
+		const char *	name;         /* May be "", will not be NULL. */
+		uint32_t	flags;
+		uint64_t	frequency;    /* In Hz. */
+	};
+}
+
+#
+# Enable the specified clock.
+# Returns 0 on success or a standard errno value.
+#
+METHOD int enable {
+	device_t	provider;
+	int		index;
+};
+
+#
+# Disable the specified clock.
+# Returns 0 on success or a standard errno value.
+#
+METHOD int disable {
+	device_t	provider;
+	int		index;
+};
+
+#
+# Returns information about the current operational state of specified clock.
+#
+METHOD int get_info {
+	device_t	provider;
+	int		index;
+	struct fdt_clock_info *info;
+};
+