1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
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/param.h>
30#include <sys/systm.h>
31#include <sys/bus.h>
32#include <sys/cpu.h>
33#include <sys/kernel.h>
34#include <sys/module.h>
35
36#include <dev/ofw/ofw_bus.h>
37
38#include "cpufreq_if.h"
39
40struct pcr_softc {
41	device_t dev;
42	uint32_t pcr_vals[3];
43	int nmodes;
44};
45
46static void	pcr_identify(driver_t *driver, device_t parent);
47static int	pcr_probe(device_t dev);
48static int	pcr_attach(device_t dev);
49static int	pcr_settings(device_t dev, struct cf_setting *sets, int *count);
50static int	pcr_set(device_t dev, const struct cf_setting *set);
51static int	pcr_get(device_t dev, struct cf_setting *set);
52static int	pcr_type(device_t dev, int *type);
53
54static device_method_t pcr_methods[] = {
55	/* Device interface */
56	DEVMETHOD(device_identify,	pcr_identify),
57	DEVMETHOD(device_probe,		pcr_probe),
58	DEVMETHOD(device_attach,	pcr_attach),
59
60	/* cpufreq interface */
61	DEVMETHOD(cpufreq_drv_set,	pcr_set),
62	DEVMETHOD(cpufreq_drv_get,	pcr_get),
63	DEVMETHOD(cpufreq_drv_type,	pcr_type),
64	DEVMETHOD(cpufreq_drv_settings,	pcr_settings),
65	{0, 0}
66};
67
68static driver_t pcr_driver = {
69	"pcr",
70	pcr_methods,
71	sizeof(struct pcr_softc)
72};
73
74DRIVER_MODULE(pcr, cpu, pcr_driver, 0, 0);
75
76/*
77 * States
78 */
79
80#define PCR_TO_FREQ(a)	((a >> 17) & 3)
81
82#define	PCR_FULL	0
83#define PCR_HALF	1
84#define PCR_QUARTER	2		/* Only on 970MP */
85
86#define PSR_RECEIVED	(1ULL << 61)
87#define PSR_COMPLETED	(1ULL << 61)
88
89/*
90 * SCOM addresses
91 */
92
93#define	SCOM_PCR	0x0aa00100	/* Power Control Register */
94#define SCOM_PCR_BIT	0x80000000	/* Data bit for PCR */
95#define SCOM_PSR	0x40800100	/* Power Status Register */
96
97/*
98 * SCOM Glue
99 */
100
101#define SCOMC_READ	0x00008000
102#define SCOMC_WRITE	0x00000000
103
104static void
105write_scom(register_t address, uint64_t value)
106{
107	register_t msr;
108	#ifndef __powerpc64__
109	register_t hi, lo, scratch;
110	#endif
111
112	msr = mfmsr();
113	mtmsr(msr & ~PSL_EE); isync();
114
115	#ifdef __powerpc64__
116	mtspr(SPR_SCOMD, value);
117	#else
118	hi = (value >> 32) & 0xffffffff;
119	lo = value & 0xffffffff;
120	mtspr64(SPR_SCOMD, hi, lo, scratch);
121	#endif
122	isync();
123	mtspr(SPR_SCOMC, address | SCOMC_WRITE);
124	isync();
125
126	mtmsr(msr); isync();
127}
128
129static uint64_t
130read_scom(register_t address)
131{
132	register_t msr;
133	uint64_t ret;
134
135	msr = mfmsr();
136	mtmsr(msr & ~PSL_EE); isync();
137
138	mtspr(SPR_SCOMC, address | SCOMC_READ);
139	isync();
140
141	__asm __volatile ("mfspr %0,%1;"
142            " mr %0+1, %0; srdi %0,%0,32" : "=r" (ret) : "K" (SPR_SCOMD));
143
144	(void)mfspr(SPR_SCOMC); /* Complete transcation */
145
146	mtmsr(msr); isync();
147
148	return (ret);
149}
150
151static void
152pcr_identify(driver_t *driver, device_t parent)
153{
154	uint16_t vers;
155	vers = mfpvr() >> 16;
156
157	/* Check for an IBM 970-class CPU */
158	switch (vers) {
159		case IBM970FX:
160		case IBM970GX:
161		case IBM970MP:
162			break;
163		default:
164			return;
165	}
166
167	/* Make sure we're not being doubly invoked. */
168	if (device_find_child(parent, "pcr", -1) != NULL)
169		return;
170
171	/*
172	 * We attach a child for every CPU since settings need to
173	 * be performed on every CPU in the SMP case.
174	 */
175	if (BUS_ADD_CHILD(parent, 10, "pcr", -1) == NULL)
176		device_printf(parent, "add pcr child failed\n");
177}
178
179static int
180pcr_probe(device_t dev)
181{
182	if (resource_disabled("pcr", 0))
183		return (ENXIO);
184
185	device_set_desc(dev, "PPC 970 Power Control Register");
186	return (0);
187}
188
189static int
190pcr_attach(device_t dev)
191{
192	struct pcr_softc *sc;
193	phandle_t cpu;
194	uint32_t modes[3];
195	int i;
196
197	sc = device_get_softc(dev);
198	sc->dev = dev;
199
200	cpu = ofw_bus_get_node(device_get_parent(dev));
201
202	if (cpu <= 0) {
203		device_printf(dev,"No CPU device tree node!\n");
204		return (ENXIO);
205	}
206
207	if (OF_getproplen(cpu, "power-mode-data") <= 0) {
208		/* Use the first CPU's node */
209		cpu = OF_child(OF_parent(cpu));
210	}
211
212	/*
213	 * Collect the PCR values for each mode from the device tree.
214	 * These include bus timing information, and so cannot be
215	 * directly computed.
216	 */
217	sc->nmodes = OF_getproplen(cpu, "power-mode-data");
218	if (sc->nmodes <= 0 || sc->nmodes > sizeof(sc->pcr_vals)) {
219		device_printf(dev,"No power mode data in device tree!\n");
220		return (ENXIO);
221	}
222	OF_getprop(cpu, "power-mode-data", modes, sc->nmodes);
223	sc->nmodes /= sizeof(modes[0]);
224
225	/* Sort the modes */
226	for (i = 0; i < sc->nmodes; i++)
227		sc->pcr_vals[PCR_TO_FREQ(modes[i])] = modes[i];
228
229	cpufreq_register(dev);
230	return (0);
231}
232
233static int
234pcr_settings(device_t dev, struct cf_setting *sets, int *count)
235{
236	struct pcr_softc *sc;
237
238	sc = device_get_softc(dev);
239	if (sets == NULL || count == NULL)
240		return (EINVAL);
241	if (*count < sc->nmodes)
242		return (E2BIG);
243
244	/* Return a list of valid settings for this driver. */
245	memset(sets, CPUFREQ_VAL_UNKNOWN, sizeof(*sets) * sc->nmodes);
246
247	sets[0].freq = 10000; sets[0].dev = dev;
248	sets[1].freq = 5000; sets[1].dev = dev;
249	if (sc->nmodes > 2) {
250		sets[2].freq = 2500;
251		sets[2].dev = dev;
252	}
253	*count = sc->nmodes;
254
255	return (0);
256}
257
258static int
259pcr_set(device_t dev, const struct cf_setting *set)
260{
261	struct pcr_softc *sc;
262	register_t pcr, msr;
263	uint64_t psr;
264
265	if (set == NULL)
266		return (EINVAL);
267	sc = device_get_softc(dev);
268
269	/* Construct the new PCR */
270
271	pcr = SCOM_PCR_BIT;
272
273	if (set->freq == 10000)
274		pcr |= sc->pcr_vals[0];
275	else if (set->freq == 5000)
276		pcr |= sc->pcr_vals[1];
277	else if (set->freq == 2500)
278		pcr |= sc->pcr_vals[2];
279
280	msr = mfmsr();
281	mtmsr(msr & ~PSL_EE); isync();
282
283	/* 970MP requires PCR and PCRH to be cleared first */
284
285	write_scom(SCOM_PCR,0);			/* Clear PCRH */
286	write_scom(SCOM_PCR,SCOM_PCR_BIT);	/* Clear PCR */
287
288	/* Set PCR */
289
290	write_scom(SCOM_PCR, pcr);
291
292	/* Wait for completion */
293
294	do {
295		DELAY(100);
296		psr = read_scom(SCOM_PSR);
297	} while ((psr & PSR_RECEIVED) && !(psr & PSR_COMPLETED));
298
299	mtmsr(msr); isync();
300
301	return (0);
302}
303
304static int
305pcr_get(device_t dev, struct cf_setting *set)
306{
307	uint64_t psr;
308
309	if (set == NULL)
310		return (EINVAL);
311
312	memset(set, CPUFREQ_VAL_UNKNOWN, sizeof(*set));
313
314	psr = read_scom(SCOM_PSR);
315
316	/* We want bits 6 and 7 */
317	psr = (psr >> 56) & 3;
318
319	set->freq = 10000;
320	if (psr == PCR_HALF)
321		set->freq = 5000;
322	else if (psr == PCR_QUARTER)
323		set->freq = 2500;
324
325	set->dev = dev;
326
327	return (0);
328}
329
330static int
331pcr_type(device_t dev, int *type)
332{
333
334	if (type == NULL)
335		return (EINVAL);
336
337	*type = CPUFREQ_TYPE_RELATIVE;
338	return (0);
339}
340