1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2009 Nathan Whitehorn
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD$");
32
33#include <sys/param.h>
34#include <sys/systm.h>
35#include <sys/module.h>
36#include <sys/bus.h>
37#include <sys/conf.h>
38#include <sys/cpu.h>
39#include <sys/eventhandler.h>
40#include <sys/kernel.h>
41#include <sys/sysctl.h>
42
43#include <dev/ofw/ofw_bus.h>
44#include <dev/ofw/openfirm.h>
45
46#include <powerpc/powermac/macgpiovar.h>
47
48static int	vcoregpio_probe(device_t);
49static int	vcoregpio_attach(device_t);
50static void	vcoregpio_pre_change(device_t, const struct cf_level *level);
51static void	vcoregpio_post_change(device_t, const struct cf_level *level);
52
53static device_method_t  vcoregpio_methods[] = {
54	/* Device interface */
55	DEVMETHOD(device_probe,		vcoregpio_probe),
56	DEVMETHOD(device_attach,	vcoregpio_attach),
57	{ 0, 0 },
58};
59
60static driver_t vcoregpio_driver = {
61	"vcoregpio",
62	vcoregpio_methods,
63	0
64};
65
66static devclass_t vcoregpio_devclass;
67
68DRIVER_MODULE(vcoregpio, macgpio, vcoregpio_driver, vcoregpio_devclass, 0, 0);
69
70static int
71vcoregpio_probe(device_t dev)
72{
73	const char *name = ofw_bus_get_name(dev);
74
75	if (strcmp(name, "cpu-vcore-select") != 0)
76		return (ENXIO);
77
78	device_set_desc(dev, "CPU Core Voltage Control");
79	return (0);
80}
81
82static int
83vcoregpio_attach(device_t dev)
84{
85	EVENTHANDLER_REGISTER(cpufreq_pre_change, vcoregpio_pre_change, dev,
86	    EVENTHANDLER_PRI_ANY);
87	EVENTHANDLER_REGISTER(cpufreq_post_change, vcoregpio_post_change, dev,
88	    EVENTHANDLER_PRI_ANY);
89
90	return (0);
91}
92
93static void
94vcoregpio_pre_change(device_t dev, const struct cf_level *level)
95{
96	if (level->rel_set[0].freq == 10000 /* max */) {
97		/*
98		 * Make sure the CPU voltage is raised before we raise
99		 * the clock.
100		 */
101		macgpio_write(dev, GPIO_DDR_OUTPUT | 1);
102		DELAY(1000);
103	}
104}
105
106static void
107vcoregpio_post_change(device_t dev, const struct cf_level *level)
108{
109	if (level->rel_set[0].freq < 10000 /* max */) {
110		DELAY(1000);
111		/* We are safe to reduce CPU voltage now */
112		macgpio_write(dev, GPIO_DDR_OUTPUT | 0);
113	}
114}
115