Introduce support for cpufreq on PowerPC with the dynamic frequency

switching capabilities of the MPC7447A and MPC7448.

1 files changed, 112 insertions, 0 deletions

diff --git a/sys/powerpc/powermac/vcoregpio.c b/sys/powerpc/powermac/vcoregpio.c
new file mode 100644
index 0000000..463e8cd
--- /dev/null
+++ b/sys/powerpc/powermac/vcoregpio.c
@@ -0,0 +1,112 @@
+/*-
+ * Copyright (c) 2009 Nathan Whitehorn
+ * 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.
+ *
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/module.h>
+#include <sys/bus.h>
+#include <sys/conf.h>
+#include <sys/cpu.h>
+#include <sys/kernel.h>
+#include <sys/sysctl.h>
+
+#include <dev/ofw/ofw_bus.h>
+#include <dev/ofw/openfirm.h>
+
+#include <powerpc/powermac/macgpiovar.h>
+
+static int	vcoregpio_probe(device_t);
+static int	vcoregpio_attach(device_t);
+static void	vcoregpio_pre_change(device_t, const struct cf_level *level);
+static void	vcoregpio_post_change(device_t, const struct cf_level *level);
+
+static device_method_t  vcoregpio_methods[] = {
+	/* Device interface */
+	DEVMETHOD(device_probe,		vcoregpio_probe),
+	DEVMETHOD(device_attach,	vcoregpio_attach),
+	{ 0, 0 },
+};
+
+static driver_t vcoregpio_driver = {
+	"vcoregpio",
+	vcoregpio_methods,
+	0
+};
+
+static devclass_t vcoregpio_devclass;
+
+DRIVER_MODULE(vcoregpio, macgpio, vcoregpio_driver, vcoregpio_devclass, 0, 0);
+
+static int
+vcoregpio_probe(device_t dev)
+{
+	const char *name = ofw_bus_get_name(dev);
+
+	if (strcmp(name, "cpu-vcore-select") != 0)
+		return (ENXIO);
+
+	device_set_desc(dev, "CPU Core Voltage Control");
+	return (0);
+}
+
+static int
+vcoregpio_attach(device_t dev)
+{
+	EVENTHANDLER_REGISTER(cpufreq_pre_change, vcoregpio_pre_change, dev,
+	    EVENTHANDLER_PRI_ANY);
+	EVENTHANDLER_REGISTER(cpufreq_post_change, vcoregpio_post_change, dev,
+	    EVENTHANDLER_PRI_ANY);
+
+	return (0);
+}
+
+static void
+vcoregpio_pre_change(device_t dev, const struct cf_level *level)
+{
+	if (level->rel_set[0].freq == 10000 /* max */) {
+		/*
+		 * Make sure the CPU voltage is raised before we raise
+		 * the clock.
+		 */
+		macgpio_write(dev, GPIO_DDR_OUTPUT | 1);
+		DELAY(1000);
+	}
+}
+
+static void
+vcoregpio_post_change(device_t dev, const struct cf_level *level)
+{
+	if (level->rel_set[0].freq < 10000 /* max */) {
+		DELAY(1000);
+		/* We are safe to reduce CPU voltage now */
+		macgpio_write(dev, GPIO_DDR_OUTPUT | 0);
+	}
+}
+