aboutsummaryrefslogtreecommitdiff
path: root/drivers/cpufreq/elanfreq.c
blob: 960671fd3d7e8c236a5f31f6577b7d174047b01a (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
/*
 *	elanfreq:	cpufreq driver for the AMD ELAN family
 *
 *	(c) Copyright 2002 Robert Schwebel <r.schwebel@pengutronix.de>
 *
 *	Parts of this code are (c) Sven Geggus <sven@geggus.net>
 *
 *      All Rights Reserved.
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 *	2002-02-13: - initial revision for 2.4.18-pre9 by Robert Schwebel
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>

#include <linux/delay.h>
#include <linux/cpufreq.h>

#include <asm/cpu_device_id.h>
#include <asm/msr.h>
#include <linux/timex.h>
#include <linux/io.h>

#define REG_CSCIR 0x22		/* Chip Setup and Control Index Register    */
#define REG_CSCDR 0x23		/* Chip Setup and Control Data  Register    */

/* Module parameter */
static int max_freq;

struct s_elan_multiplier {
	int clock;		/* frequency in kHz                         */
	int val40h;		/* PMU Force Mode register                  */
	int val80h;		/* CPU Clock Speed Register                 */
};

/*
 * It is important that the frequencies
 * are listed in ascending order here!
 */
static struct s_elan_multiplier elan_multiplier[] = {
	{1000,	0x02,	0x18},
	{2000,	0x02,	0x10},
	{4000,	0x02,	0x08},
	{8000,	0x00,	0x00},
	{16000,	0x00,	0x02},
	{33000,	0x00,	0x04},
	{66000,	0x01,	0x04},
	{99000,	0x01,	0x05}
};

static struct cpufreq_frequency_table elanfreq_table[] = {
	{0,	1000},
	{1,	2000},
	{2,	4000},
	{3,	8000},
	{4,	16000},
	{5,	33000},
	{6,	66000},
	{7,	99000},
	{0,	CPUFREQ_TABLE_END},
};


/**
 *	elanfreq_get_cpu_frequency: determine current cpu speed
 *
 *	Finds out at which frequency the CPU of the Elan SOC runs
 *	at the moment. Frequencies from 1 to 33 MHz are generated
 *	the normal way, 66 and 99 MHz are called "Hyperspeed Mode"
 *	and have the rest of the chip running with 33 MHz.
 */

static unsigned int elanfreq_get_cpu_frequency(unsigned int cpu)
{
	u8 clockspeed_reg;    /* Clock Speed Register */

	local_irq_disable();
	outb_p(0x80, REG_CSCIR);
	clockspeed_reg = inb_p(REG_CSCDR);
	local_irq_enable();

	if ((clockspeed_reg & 0xE0) == 0xE0)
		return 0;

	/* Are we in CPU clock multiplied mode (66/99 MHz)? */
	if ((clockspeed_reg & 0xE0) == 0xC0) {
		if ((clockspeed_reg & 0x01) == 0)
			return 66000;
		else
			return 99000;
	}

	/* 33 MHz is not 32 MHz... */
	if ((clockspeed_reg & 0xE0) == 0xA0)
		return 33000;

	return (1<<((clockspeed_reg & 0xE0) >> 5)) * 1000;
}


/**
 *	elanfreq_set_cpu_frequency: Change the CPU core frequency
 *	@cpu: cpu number
 *	@freq: frequency in kHz
 *
 *	This function takes a frequency value and changes the CPU frequency
 *	according to this. Note that the frequency has to be checked by
 *	elanfreq_validatespeed() for correctness!
 *
 *	There is no return value.
 */

static void elanfreq_set_cpu_state(unsigned int state)
{
	struct cpufreq_freqs    freqs;

	freqs.old = elanfreq_get_cpu_frequency(0);
	freqs.new = elan_multiplier[state].clock;
	freqs.cpu = 0; /* elanfreq.c is UP only driver */

	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

	printk(KERN_INFO "elanfreq: attempting to set frequency to %i kHz\n",
			elan_multiplier[state].clock);


	/*
	 * Access to the Elan's internal registers is indexed via
	 * 0x22: Chip Setup & Control Register Index Register (CSCI)
	 * 0x23: Chip Setup & Control Register Data  Register (CSCD)
	 *
	 */

	/*
	 * 0x40 is the Power Management Unit's Force Mode Register.
	 * Bit 6 enables Hyperspeed Mode (66/100 MHz core frequency)
	 */

	local_irq_disable();
	outb_p(0x40, REG_CSCIR);		/* Disable hyperspeed mode */
	outb_p(0x00, REG_CSCDR);
	local_irq_enable();		/* wait till internal pipelines and */
	udelay(1000);			/* buffers have cleaned up          */

	local_irq_disable();

	/* now, set the CPU clock speed register (0x80) */
	outb_p(0x80, REG_CSCIR);
	outb_p(elan_multiplier[state].val80h, REG_CSCDR);

	/* now, the hyperspeed bit in PMU Force Mode Register (0x40) */
	outb_p(0x40, REG_CSCIR);
	outb_p(elan_multiplier[state].val40h, REG_CSCDR);
	udelay(10000);
	local_irq_enable();

	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
};


/**
 *	elanfreq_validatespeed: test if frequency range is valid
 *	@policy: the policy to validate
 *
 *	This function checks if a given frequency range in kHz is valid
 *	for the hardware supported by the driver.
 */

static int elanfreq_verify(struct cpufreq_policy *policy)
{
	return cpufreq_frequency_table_verify(policy, &elanfreq_table[0]);
}

static int elanfreq_target(struct cpufreq_policy *policy,
			    unsigned int target_freq,
			    unsigned int relation)
{
	unsigned int newstate = 0;

	if (cpufreq_frequency_table_target(policy, &elanfreq_table[0],
				target_freq, relation, &newstate))
		return -EINVAL;

	elanfreq_set_cpu_state(newstate);

	return 0;
}


/*
 *	Module init and exit code
 */

static int elanfreq_cpu_init(struct cpufreq_policy *policy)
{
	struct cpuinfo_x86 *c = &cpu_data(0);
	unsigned int i;
	int result;

	/* capability check */
	if ((c->x86_vendor != X86_VENDOR_AMD) ||
	    (c->x86 != 4) || (c->x86_model != 10))
		return -ENODEV;

	/* max freq */
	if (!max_freq)
		max_freq = elanfreq_get_cpu_frequency(0);

	/* table init */
	for (i = 0; (elanfreq_table[i].frequency != CPUFREQ_TABLE_END); i++) {
		if (elanfreq_table[i].frequency > max_freq)
			elanfreq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
	}

	/* cpuinfo and default policy values */
	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
	policy->cur = elanfreq_get_cpu_frequency(0);

	result = cpufreq_frequency_table_cpuinfo(policy, elanfreq_table);
	if (result)
		return result;

	cpufreq_frequency_table_get_attr(elanfreq_table, policy->cpu);
	return 0;
}


static int elanfreq_cpu_exit(struct cpufreq_policy *policy)
{
	cpufreq_frequency_table_put_attr(policy->cpu);
	return 0;
}


#ifndef MODULE
/**
 * elanfreq_setup - elanfreq command line parameter parsing
 *
 * elanfreq command line parameter.  Use:
 *  elanfreq=66000
 * to set the maximum CPU frequency to 66 MHz. Note that in
 * case you do not give this boot parameter, the maximum
 * frequency will fall back to _current_ CPU frequency which
 * might be lower. If you build this as a module, use the
 * max_freq module parameter instead.
 */
static int __init elanfreq_setup(char *str)
{
	max_freq = simple_strtoul(str, &str, 0);
	printk(KERN_WARNING "You're using the deprecated elanfreq command line option. Use elanfreq.max_freq instead, please!\n");
	return 1;
}
__setup("elanfreq=", elanfreq_setup);
#endif


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


static struct cpufreq_driver elanfreq_driver = {
	.get		= elanfreq_get_cpu_frequency,
	.verify		= elanfreq_verify,
	.target		= elanfreq_target,
	.init		= elanfreq_cpu_init,
	.exit		= elanfreq_cpu_exit,
	.name		= "elanfreq",
	.owner		= THIS_MODULE,
	.attr		= elanfreq_attr,
};

static const struct x86_cpu_id elan_id[] = {
	{ X86_VENDOR_AMD, 4, 10, },
	{}
};
MODULE_DEVICE_TABLE(x86cpu, elan_id);

static int __init elanfreq_init(void)
{
	if (!x86_match_cpu(elan_id))
		return -ENODEV;
	return cpufreq_register_driver(&elanfreq_driver);
}


static void __exit elanfreq_exit(void)
{
	cpufreq_unregister_driver(&elanfreq_driver);
}


module_param(max_freq, int, 0444);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Robert Schwebel <r.schwebel@pengutronix.de>, "
		"Sven Geggus <sven@geggus.net>");
MODULE_DESCRIPTION("cpufreq driver for AMD's Elan CPUs");

module_init(elanfreq_init);
module_exit(elanfreq_exit);