aboutsummaryrefslogtreecommitdiff
path: root/drivers/cpufreq/maple-cpufreq.c
blob: d4c4989823dc4832ac0d80db79bd8ee338ccd54b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
/*
 *  Copyright (C) 2011 Dmitry Eremin-Solenikov
 *  Copyright (C) 2002 - 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
 *  and                       Markus Demleitner <msdemlei@cl.uni-heidelberg.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This driver adds basic cpufreq support for SMU & 970FX based G5 Macs,
 * that is iMac G5 and latest single CPU desktop.
 */

#undef DEBUG

#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/cpufreq.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/mutex.h>
#include <linux/time.h>
#include <linux/of.h>

#define DBG(fmt...) pr_debug(fmt)

/* see 970FX user manual */

#define SCOM_PCR 0x0aa001			/* PCR scom addr */

#define PCR_HILO_SELECT		0x80000000U	/* 1 = PCR, 0 = PCRH */
#define PCR_SPEED_FULL		0x00000000U	/* 1:1 speed value */
#define PCR_SPEED_HALF		0x00020000U	/* 1:2 speed value */
#define PCR_SPEED_QUARTER	0x00040000U	/* 1:4 speed value */
#define PCR_SPEED_MASK		0x000e0000U	/* speed mask */
#define PCR_SPEED_SHIFT		17
#define PCR_FREQ_REQ_VALID	0x00010000U	/* freq request valid */
#define PCR_VOLT_REQ_VALID	0x00008000U	/* volt request valid */
#define PCR_TARGET_TIME_MASK	0x00006000U	/* target time */
#define PCR_STATLAT_MASK	0x00001f00U	/* STATLAT value */
#define PCR_SNOOPLAT_MASK	0x000000f0U	/* SNOOPLAT value */
#define PCR_SNOOPACC_MASK	0x0000000fU	/* SNOOPACC value */

#define SCOM_PSR 0x408001			/* PSR scom addr */
/* warning: PSR is a 64 bits register */
#define PSR_CMD_RECEIVED	0x2000000000000000U   /* command received */
#define PSR_CMD_COMPLETED	0x1000000000000000U   /* command completed */
#define PSR_CUR_SPEED_MASK	0x0300000000000000U   /* current speed */
#define PSR_CUR_SPEED_SHIFT	(56)

/*
 * The G5 only supports two frequencies (Quarter speed is not supported)
 */
#define CPUFREQ_HIGH                  0
#define CPUFREQ_LOW                   1

static struct cpufreq_frequency_table maple_cpu_freqs[] = {
	{CPUFREQ_HIGH,		0},
	{CPUFREQ_LOW,		0},
	{0,			CPUFREQ_TABLE_END},
};

static struct freq_attr *maple_cpu_freqs_attr[] = {
	&cpufreq_freq_attr_scaling_available_freqs,
	NULL,
};

/* Power mode data is an array of the 32 bits PCR values to use for
 * the various frequencies, retrieved from the device-tree
 */
static int maple_pmode_cur;

static DEFINE_MUTEX(maple_switch_mutex);

static const u32 *maple_pmode_data;
static int maple_pmode_max;

/*
 * SCOM based frequency switching for 970FX rev3
 */
static int maple_scom_switch_freq(int speed_mode)
{
	unsigned long flags;
	int to;

	local_irq_save(flags);

	/* Clear PCR high */
	scom970_write(SCOM_PCR, 0);
	/* Clear PCR low */
	scom970_write(SCOM_PCR, PCR_HILO_SELECT | 0);
	/* Set PCR low */
	scom970_write(SCOM_PCR, PCR_HILO_SELECT |
		      maple_pmode_data[speed_mode]);

	/* Wait for completion */
	for (to = 0; to < 10; to++) {
		unsigned long psr = scom970_read(SCOM_PSR);

		if ((psr & PSR_CMD_RECEIVED) == 0 &&
		    (((psr >> PSR_CUR_SPEED_SHIFT) ^
		      (maple_pmode_data[speed_mode] >> PCR_SPEED_SHIFT)) & 0x3)
		    == 0)
			break;
		if (psr & PSR_CMD_COMPLETED)
			break;
		udelay(100);
	}

	local_irq_restore(flags);

	maple_pmode_cur = speed_mode;
	ppc_proc_freq = maple_cpu_freqs[speed_mode].frequency * 1000ul;

	return 0;
}

static int maple_scom_query_freq(void)
{
	unsigned long psr = scom970_read(SCOM_PSR);
	int i;

	for (i = 0; i <= maple_pmode_max; i++)
		if ((((psr >> PSR_CUR_SPEED_SHIFT) ^
		      (maple_pmode_data[i] >> PCR_SPEED_SHIFT)) & 0x3) == 0)
			break;
	return i;
}

/*
 * Common interface to the cpufreq core
 */

static int maple_cpufreq_verify(struct cpufreq_policy *policy)
{
	return cpufreq_frequency_table_verify(policy, maple_cpu_freqs);
}

static int maple_cpufreq_target(struct cpufreq_policy *policy,
	unsigned int target_freq, unsigned int relation)
{
	unsigned int newstate = 0;
	struct cpufreq_freqs freqs;
	int rc;

	if (cpufreq_frequency_table_target(policy, maple_cpu_freqs,
			target_freq, relation, &newstate))
		return -EINVAL;

	if (maple_pmode_cur == newstate)
		return 0;

	mutex_lock(&maple_switch_mutex);

	freqs.old = maple_cpu_freqs[maple_pmode_cur].frequency;
	freqs.new = maple_cpu_freqs[newstate].frequency;
	freqs.cpu = 0;

	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
	rc = maple_scom_switch_freq(newstate);
	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

	mutex_unlock(&maple_switch_mutex);

	return rc;
}

static unsigned int maple_cpufreq_get_speed(unsigned int cpu)
{
	return maple_cpu_freqs[maple_pmode_cur].frequency;
}

static int maple_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
	policy->cpuinfo.transition_latency = 12000;
	policy->cur = maple_cpu_freqs[maple_scom_query_freq()].frequency;
	/* secondary CPUs are tied to the primary one by the
	 * cpufreq core if in the secondary policy we tell it that
	 * it actually must be one policy together with all others. */
	cpumask_setall(policy->cpus);
	cpufreq_frequency_table_get_attr(maple_cpu_freqs, policy->cpu);

	return cpufreq_frequency_table_cpuinfo(policy,
		maple_cpu_freqs);
}


static struct cpufreq_driver maple_cpufreq_driver = {
	.name		= "maple",
	.owner		= THIS_MODULE,
	.flags		= CPUFREQ_CONST_LOOPS,
	.init		= maple_cpufreq_cpu_init,
	.verify		= maple_cpufreq_verify,
	.target		= maple_cpufreq_target,
	.get		= maple_cpufreq_get_speed,
	.attr		= maple_cpu_freqs_attr,
};

static int __init maple_cpufreq_init(void)
{
	struct device_node *cpus;
	struct device_node *cpunode;
	unsigned int psize;
	unsigned long max_freq;
	const u32 *valp;
	u32 pvr_hi;
	int rc = -ENODEV;

	/*
	 * Behave here like powermac driver which checks machine compatibility
	 * to ease merging of two drivers in future.
	 */
	if (!of_machine_is_compatible("Momentum,Maple") &&
	    !of_machine_is_compatible("Momentum,Apache"))
		return 0;

	cpus = of_find_node_by_path("/cpus");
	if (cpus == NULL) {
		DBG("No /cpus node !\n");
		return -ENODEV;
	}

	/* Get first CPU node */
	for (cpunode = NULL;
	     (cpunode = of_get_next_child(cpus, cpunode)) != NULL;) {
		const u32 *reg = of_get_property(cpunode, "reg", NULL);
		if (reg == NULL || (*reg) != 0)
			continue;
		if (!strcmp(cpunode->type, "cpu"))
			break;
	}
	if (cpunode == NULL) {
		printk(KERN_ERR "cpufreq: Can't find any CPU 0 node\n");
		goto bail_cpus;
	}

	/* Check 970FX for now */
	/* we actually don't care on which CPU to access PVR */
	pvr_hi = PVR_VER(mfspr(SPRN_PVR));
	if (pvr_hi != 0x3c && pvr_hi != 0x44) {
		printk(KERN_ERR "cpufreq: Unsupported CPU version (%x)\n",
				pvr_hi);
		goto bail_noprops;
	}

	/* Look for the powertune data in the device-tree */
	/*
	 * On Maple this property is provided by PIBS in dual-processor config,
	 * not provided by PIBS in CPU0 config and also not provided by SLOF,
	 * so YMMV
	 */
	maple_pmode_data = of_get_property(cpunode, "power-mode-data", &psize);
	if (!maple_pmode_data) {
		DBG("No power-mode-data !\n");
		goto bail_noprops;
	}
	maple_pmode_max = psize / sizeof(u32) - 1;

	/*
	 * From what I see, clock-frequency is always the maximal frequency.
	 * The current driver can not slew sysclk yet, so we really only deal
	 * with powertune steps for now. We also only implement full freq and
	 * half freq in this version. So far, I haven't yet seen a machine
	 * supporting anything else.
	 */
	valp = of_get_property(cpunode, "clock-frequency", NULL);
	if (!valp)
		return -ENODEV;
	max_freq = (*valp)/1000;
	maple_cpu_freqs[0].frequency = max_freq;
	maple_cpu_freqs[1].frequency = max_freq/2;

	/* Force apply current frequency to make sure everything is in
	 * sync (voltage is right for example). Firmware may leave us with
	 * a strange setting ...
	 */
	msleep(10);
	maple_pmode_cur = -1;
	maple_scom_switch_freq(maple_scom_query_freq());

	printk(KERN_INFO "Registering Maple CPU frequency driver\n");
	printk(KERN_INFO "Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n",
		maple_cpu_freqs[1].frequency/1000,
		maple_cpu_freqs[0].frequency/1000,
		maple_cpu_freqs[maple_pmode_cur].frequency/1000);

	rc = cpufreq_register_driver(&maple_cpufreq_driver);

	of_node_put(cpunode);
	of_node_put(cpus);

	return rc;

bail_noprops:
	of_node_put(cpunode);
bail_cpus:
	of_node_put(cpus);

	return rc;
}

module_init(maple_cpufreq_init);


MODULE_LICENSE("GPL");