1/*
2 *	elanfreq:	cpufreq driver for the AMD ELAN family
3 *
4 *	(c) Copyright 2002 Robert Schwebel <r.schwebel@pengutronix.de>
5 *
6 *	Parts of this code are (c) Sven Geggus <sven@geggus.net>
7 *
8 *      All Rights Reserved.
9 *
10 *	This program is free software; you can redistribute it and/or
11 *	modify it under the terms of the GNU General Public License
12 *	as published by the Free Software Foundation; either version
13 *	2 of the License, or (at your option) any later version.
14 *
15 *	2002-02-13: - initial revision for 2.4.18-pre9 by Robert Schwebel
16 *
17 */
18
19#include <linux/kernel.h>
20#include <linux/module.h>
21#include <linux/init.h>
22
23#include <linux/delay.h>
24#include <linux/cpufreq.h>
25
26#include <asm/cpu_device_id.h>
27#include <asm/msr.h>
28#include <linux/timex.h>
29#include <linux/io.h>
30
31#define REG_CSCIR 0x22		/* Chip Setup and Control Index Register    */
32#define REG_CSCDR 0x23		/* Chip Setup and Control Data  Register    */
33
34/* Module parameter */
35static int max_freq;
36
37struct s_elan_multiplier {
38	int clock;		/* frequency in kHz                         */
39	int val40h;		/* PMU Force Mode register                  */
40	int val80h;		/* CPU Clock Speed Register                 */
41};
42
43/*
44 * It is important that the frequencies
45 * are listed in ascending order here!
46 */
47static struct s_elan_multiplier elan_multiplier[] = {
48	{1000,	0x02,	0x18},
49	{2000,	0x02,	0x10},
50	{4000,	0x02,	0x08},
51	{8000,	0x00,	0x00},
52	{16000,	0x00,	0x02},
53	{33000,	0x00,	0x04},
54	{66000,	0x01,	0x04},
55	{99000,	0x01,	0x05}
56};
57
58static struct cpufreq_frequency_table elanfreq_table[] = {
59	{0, 0,	1000},
60	{0, 1,	2000},
61	{0, 2,	4000},
62	{0, 3,	8000},
63	{0, 4,	16000},
64	{0, 5,	33000},
65	{0, 6,	66000},
66	{0, 7,	99000},
67	{0, 0,	CPUFREQ_TABLE_END},
68};
69
70
71/**
72 *	elanfreq_get_cpu_frequency: determine current cpu speed
73 *
74 *	Finds out at which frequency the CPU of the Elan SOC runs
75 *	at the moment. Frequencies from 1 to 33 MHz are generated
76 *	the normal way, 66 and 99 MHz are called "Hyperspeed Mode"
77 *	and have the rest of the chip running with 33 MHz.
78 */
79
80static unsigned int elanfreq_get_cpu_frequency(unsigned int cpu)
81{
82	u8 clockspeed_reg;    /* Clock Speed Register */
83
84	local_irq_disable();
85	outb_p(0x80, REG_CSCIR);
86	clockspeed_reg = inb_p(REG_CSCDR);
87	local_irq_enable();
88
89	if ((clockspeed_reg & 0xE0) == 0xE0)
90		return 0;
91
92	/* Are we in CPU clock multiplied mode (66/99 MHz)? */
93	if ((clockspeed_reg & 0xE0) == 0xC0) {
94		if ((clockspeed_reg & 0x01) == 0)
95			return 66000;
96		else
97			return 99000;
98	}
99
100	/* 33 MHz is not 32 MHz... */
101	if ((clockspeed_reg & 0xE0) == 0xA0)
102		return 33000;
103
104	return (1<<((clockspeed_reg & 0xE0) >> 5)) * 1000;
105}
106
107
108static int elanfreq_target(struct cpufreq_policy *policy,
109			    unsigned int state)
110{
111	/*
112	 * Access to the Elan's internal registers is indexed via
113	 * 0x22: Chip Setup & Control Register Index Register (CSCI)
114	 * 0x23: Chip Setup & Control Register Data  Register (CSCD)
115	 *
116	 */
117
118	/*
119	 * 0x40 is the Power Management Unit's Force Mode Register.
120	 * Bit 6 enables Hyperspeed Mode (66/100 MHz core frequency)
121	 */
122
123	local_irq_disable();
124	outb_p(0x40, REG_CSCIR);		/* Disable hyperspeed mode */
125	outb_p(0x00, REG_CSCDR);
126	local_irq_enable();		/* wait till internal pipelines and */
127	udelay(1000);			/* buffers have cleaned up          */
128
129	local_irq_disable();
130
131	/* now, set the CPU clock speed register (0x80) */
132	outb_p(0x80, REG_CSCIR);
133	outb_p(elan_multiplier[state].val80h, REG_CSCDR);
134
135	/* now, the hyperspeed bit in PMU Force Mode Register (0x40) */
136	outb_p(0x40, REG_CSCIR);
137	outb_p(elan_multiplier[state].val40h, REG_CSCDR);
138	udelay(10000);
139	local_irq_enable();
140
141	return 0;
142}
143/*
144 *	Module init and exit code
145 */
146
147static int elanfreq_cpu_init(struct cpufreq_policy *policy)
148{
149	struct cpuinfo_x86 *c = &cpu_data(0);
150	struct cpufreq_frequency_table *pos;
151
152	/* capability check */
153	if ((c->x86_vendor != X86_VENDOR_AMD) ||
154	    (c->x86 != 4) || (c->x86_model != 10))
155		return -ENODEV;
156
157	/* max freq */
158	if (!max_freq)
159		max_freq = elanfreq_get_cpu_frequency(0);
160
161	/* table init */
162	cpufreq_for_each_entry(pos, elanfreq_table)
163		if (pos->frequency > max_freq)
164			pos->frequency = CPUFREQ_ENTRY_INVALID;
165
166	/* cpuinfo and default policy values */
167	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
168
169	return cpufreq_table_validate_and_show(policy, elanfreq_table);
170}
171
172
173#ifndef MODULE
174/**
175 * elanfreq_setup - elanfreq command line parameter parsing
176 *
177 * elanfreq command line parameter.  Use:
178 *  elanfreq=66000
179 * to set the maximum CPU frequency to 66 MHz. Note that in
180 * case you do not give this boot parameter, the maximum
181 * frequency will fall back to _current_ CPU frequency which
182 * might be lower. If you build this as a module, use the
183 * max_freq module parameter instead.
184 */
185static int __init elanfreq_setup(char *str)
186{
187	max_freq = simple_strtoul(str, &str, 0);
188	printk(KERN_WARNING "You're using the deprecated elanfreq command line option. Use elanfreq.max_freq instead, please!\n");
189	return 1;
190}
191__setup("elanfreq=", elanfreq_setup);
192#endif
193
194
195static struct cpufreq_driver elanfreq_driver = {
196	.get		= elanfreq_get_cpu_frequency,
197	.verify		= cpufreq_generic_frequency_table_verify,
198	.target_index	= elanfreq_target,
199	.init		= elanfreq_cpu_init,
200	.name		= "elanfreq",
201	.attr		= cpufreq_generic_attr,
202};
203
204static const struct x86_cpu_id elan_id[] = {
205	{ X86_VENDOR_AMD, 4, 10, },
206	{}
207};
208MODULE_DEVICE_TABLE(x86cpu, elan_id);
209
210static int __init elanfreq_init(void)
211{
212	if (!x86_match_cpu(elan_id))
213		return -ENODEV;
214	return cpufreq_register_driver(&elanfreq_driver);
215}
216
217
218static void __exit elanfreq_exit(void)
219{
220	cpufreq_unregister_driver(&elanfreq_driver);
221}
222
223
224module_param(max_freq, int, 0444);
225
226MODULE_LICENSE("GPL");
227MODULE_AUTHOR("Robert Schwebel <r.schwebel@pengutronix.de>, "
228		"Sven Geggus <sven@geggus.net>");
229MODULE_DESCRIPTION("cpufreq driver for AMD's Elan CPUs");
230
231module_init(elanfreq_init);
232module_exit(elanfreq_exit);
233