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#include <sys/cdefs.h>
30__FBSDID("$FreeBSD$");
31
32#include <sys/param.h>
33#include <sys/systm.h>
34#include <sys/bus.h>
35#include <sys/cpu.h>
36#include <sys/kernel.h>
37#include <sys/module.h>
38
39#include "cpufreq_if.h"
40
41struct dfs_softc {
42	device_t dev;
43	int	 dfs4;
44};
45
46static void	dfs_identify(driver_t *driver, device_t parent);
47static int	dfs_probe(device_t dev);
48static int	dfs_attach(device_t dev);
49static int	dfs_settings(device_t dev, struct cf_setting *sets, int *count);
50static int	dfs_set(device_t dev, const struct cf_setting *set);
51static int	dfs_get(device_t dev, struct cf_setting *set);
52static int	dfs_type(device_t dev, int *type);
53
54static device_method_t dfs_methods[] = {
55	/* Device interface */
56	DEVMETHOD(device_identify,	dfs_identify),
57	DEVMETHOD(device_probe,		dfs_probe),
58	DEVMETHOD(device_attach,	dfs_attach),
59
60	/* cpufreq interface */
61	DEVMETHOD(cpufreq_drv_set,	dfs_set),
62	DEVMETHOD(cpufreq_drv_get,	dfs_get),
63	DEVMETHOD(cpufreq_drv_type,	dfs_type),
64	DEVMETHOD(cpufreq_drv_settings,	dfs_settings),
65	{0, 0}
66};
67
68static driver_t dfs_driver = {
69	"dfs",
70	dfs_methods,
71	sizeof(struct dfs_softc)
72};
73
74static devclass_t dfs_devclass;
75DRIVER_MODULE(dfs, cpu, dfs_driver, dfs_devclass, 0, 0);
76
77/*
78 * Bits of the HID1 register to enable DFS. See page 2-24 of "MPC7450
79 * RISC Microprocessor Family Reference Manual", rev. 5.
80 */
81
82#define	HID1_DFS2	(1UL << 22)
83#define	HID1_DFS4	(1UL << 23)
84
85static void
86dfs_identify(driver_t *driver, device_t parent)
87{
88	uint16_t vers;
89	vers = mfpvr() >> 16;
90
91	/* Check for an MPC 7447A or 7448 CPU */
92	switch (vers) {
93		case MPC7447A:
94		case MPC7448:
95			break;
96		default:
97			return;
98	}
99
100	/* Make sure we're not being doubly invoked. */
101	if (device_find_child(parent, "dfs", -1) != NULL)
102		return;
103
104	/*
105	 * We attach a child for every CPU since settings need to
106	 * be performed on every CPU in the SMP case.
107	 */
108	if (BUS_ADD_CHILD(parent, 10, "dfs", -1) == NULL)
109		device_printf(parent, "add dfs child failed\n");
110}
111
112static int
113dfs_probe(device_t dev)
114{
115	if (resource_disabled("dfs", 0))
116		return (ENXIO);
117
118	device_set_desc(dev, "Dynamic Frequency Switching");
119	return (0);
120}
121
122static int
123dfs_attach(device_t dev)
124{
125	struct dfs_softc *sc;
126	uint16_t vers;
127
128	sc = device_get_softc(dev);
129	sc->dev = dev;
130	sc->dfs4 = 0;
131	vers = mfpvr() >> 16;
132
133	/* The 7448 supports divide-by-four as well */
134	if (vers == MPC7448)
135		sc->dfs4 = 1;
136
137	cpufreq_register(dev);
138	return (0);
139}
140
141static int
142dfs_settings(device_t dev, struct cf_setting *sets, int *count)
143{
144	struct dfs_softc *sc;
145	int states;
146
147	sc = device_get_softc(dev);
148	states = sc->dfs4 ? 3 : 2;
149	if (sets == NULL || count == NULL)
150		return (EINVAL);
151	if (*count < states)
152		return (E2BIG);
153
154	/* Return a list of valid settings for this driver. */
155	memset(sets, CPUFREQ_VAL_UNKNOWN, sizeof(*sets) * states);
156
157	sets[0].freq = 10000; sets[0].dev = dev;
158	sets[1].freq = 5000; sets[1].dev = dev;
159	if (sc->dfs4) {
160		sets[2].freq = 2500;
161		sets[2].dev = dev;
162	}
163	*count = states;
164
165	return (0);
166}
167
168static int
169dfs_set(device_t dev, const struct cf_setting *set)
170{
171	register_t hid1;
172
173	if (set == NULL)
174		return (EINVAL);
175
176	hid1 = mfspr(SPR_HID1);
177	hid1 &= ~(HID1_DFS2 | HID1_DFS4);
178
179	if (set->freq == 5000)
180		hid1 |= HID1_DFS2;
181	else if (set->freq == 2500)
182		hid1 |= HID1_DFS4;
183
184	/*
185	 * Now set the HID1 register with new values. Calling sequence
186	 * taken from page 2-26 of the MPC7450 family CPU manual.
187	 */
188
189	powerpc_sync();
190	mtspr(SPR_HID1, hid1);
191	powerpc_sync(); isync();
192
193	return (0);
194}
195
196static int
197dfs_get(device_t dev, struct cf_setting *set)
198{
199	struct dfs_softc *sc;
200	register_t hid1;
201
202	if (set == NULL)
203		return (EINVAL);
204	sc = device_get_softc(dev);
205
206	memset(set, CPUFREQ_VAL_UNKNOWN, sizeof(*set));
207
208	hid1 = mfspr(SPR_HID1);
209
210	set->freq = 10000;
211	if (hid1 & HID1_DFS2)
212		set->freq = 5000;
213	else if (sc->dfs4 && (hid1 & HID1_DFS4))
214		set->freq = 2500;
215
216	set->dev = dev;
217
218	return (0);
219}
220
221static int
222dfs_type(device_t dev, int *type)
223{
224
225	if (type == NULL)
226		return (EINVAL);
227
228	*type = CPUFREQ_TYPE_RELATIVE;
229	return (0);
230}
231