powernow-k6.c revision bb0a56ecc4ba2a3db1b6ea6949c309886e3447d3 
1/*
2 *  This file was based upon code in Powertweak Linux (http://powertweak.sf.net)
3 *  (C) 2000-2003  Dave Jones, Arjan van de Ven, Janne Pänkälä,
4 *                 Dominik Brodowski.
5 *
6 *  Licensed under the terms of the GNU GPL License version 2.
7 *
8 *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
9 */
10
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/cpufreq.h>
15#include <linux/ioport.h>
16#include <linux/timex.h>
17#include <linux/io.h>
18
19#include <asm/msr.h>
20
21#define POWERNOW_IOPORT 0xfff0          /* it doesn't matter where, as long
22					   as it is unused */
23
24#define PFX "powernow-k6: "
25static unsigned int                     busfreq;   /* FSB, in 10 kHz */
26static unsigned int                     max_multiplier;
27
28
29/* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
30static struct cpufreq_frequency_table clock_ratio[] = {
31	{45,  /* 000 -> 4.5x */ 0},
32	{50,  /* 001 -> 5.0x */ 0},
33	{40,  /* 010 -> 4.0x */ 0},
34	{55,  /* 011 -> 5.5x */ 0},
35	{20,  /* 100 -> 2.0x */ 0},
36	{30,  /* 101 -> 3.0x */ 0},
37	{60,  /* 110 -> 6.0x */ 0},
38	{35,  /* 111 -> 3.5x */ 0},
39	{0, CPUFREQ_TABLE_END}
40};
41
42
43/**
44 * powernow_k6_get_cpu_multiplier - returns the current FSB multiplier
45 *
46 *   Returns the current setting of the frequency multiplier. Core clock
47 * speed is frequency of the Front-Side Bus multiplied with this value.
48 */
49static int powernow_k6_get_cpu_multiplier(void)
50{
51	u64 invalue = 0;
52	u32 msrval;
53
54	msrval = POWERNOW_IOPORT + 0x1;
55	wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
56	invalue = inl(POWERNOW_IOPORT + 0x8);
57	msrval = POWERNOW_IOPORT + 0x0;
58	wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
59
60	return clock_ratio[(invalue >> 5)&7].index;
61}
62
63
64/**
65 * powernow_k6_set_state - set the PowerNow! multiplier
66 * @best_i: clock_ratio[best_i] is the target multiplier
67 *
68 *   Tries to change the PowerNow! multiplier
69 */
70static void powernow_k6_set_state(unsigned int best_i)
71{
72	unsigned long outvalue = 0, invalue = 0;
73	unsigned long msrval;
74	struct cpufreq_freqs freqs;
75
76	if (clock_ratio[best_i].index > max_multiplier) {
77		printk(KERN_ERR PFX "invalid target frequency\n");
78		return;
79	}
80
81	freqs.old = busfreq * powernow_k6_get_cpu_multiplier();
82	freqs.new = busfreq * clock_ratio[best_i].index;
83	freqs.cpu = 0; /* powernow-k6.c is UP only driver */
84
85	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
86
87	/* we now need to transform best_i to the BVC format, see AMD#23446 */
88
89	outvalue = (1<<12) | (1<<10) | (1<<9) | (best_i<<5);
90
91	msrval = POWERNOW_IOPORT + 0x1;
92	wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
93	invalue = inl(POWERNOW_IOPORT + 0x8);
94	invalue = invalue & 0xf;
95	outvalue = outvalue | invalue;
96	outl(outvalue , (POWERNOW_IOPORT + 0x8));
97	msrval = POWERNOW_IOPORT + 0x0;
98	wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
99
100	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
101
102	return;
103}
104
105
106/**
107 * powernow_k6_verify - verifies a new CPUfreq policy
108 * @policy: new policy
109 *
110 * Policy must be within lowest and highest possible CPU Frequency,
111 * and at least one possible state must be within min and max.
112 */
113static int powernow_k6_verify(struct cpufreq_policy *policy)
114{
115	return cpufreq_frequency_table_verify(policy, &clock_ratio[0]);
116}
117
118
119/**
120 * powernow_k6_setpolicy - sets a new CPUFreq policy
121 * @policy: new policy
122 * @target_freq: the target frequency
123 * @relation: how that frequency relates to achieved frequency
124 *  (CPUFREQ_RELATION_L or CPUFREQ_RELATION_H)
125 *
126 * sets a new CPUFreq policy
127 */
128static int powernow_k6_target(struct cpufreq_policy *policy,
129			       unsigned int target_freq,
130			       unsigned int relation)
131{
132	unsigned int newstate = 0;
133
134	if (cpufreq_frequency_table_target(policy, &clock_ratio[0],
135				target_freq, relation, &newstate))
136		return -EINVAL;
137
138	powernow_k6_set_state(newstate);
139
140	return 0;
141}
142
143
144static int powernow_k6_cpu_init(struct cpufreq_policy *policy)
145{
146	unsigned int i, f;
147	int result;
148
149	if (policy->cpu != 0)
150		return -ENODEV;
151
152	/* get frequencies */
153	max_multiplier = powernow_k6_get_cpu_multiplier();
154	busfreq = cpu_khz / max_multiplier;
155
156	/* table init */
157	for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
158		f = clock_ratio[i].index;
159		if (f > max_multiplier)
160			clock_ratio[i].frequency = CPUFREQ_ENTRY_INVALID;
161		else
162			clock_ratio[i].frequency = busfreq * f;
163	}
164
165	/* cpuinfo and default policy values */
166	policy->cpuinfo.transition_latency = 200000;
167	policy->cur = busfreq * max_multiplier;
168
169	result = cpufreq_frequency_table_cpuinfo(policy, clock_ratio);
170	if (result)
171		return result;
172
173	cpufreq_frequency_table_get_attr(clock_ratio, policy->cpu);
174
175	return 0;
176}
177
178
179static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
180{
181	unsigned int i;
182	for (i = 0; i < 8; i++) {
183		if (i == max_multiplier)
184			powernow_k6_set_state(i);
185	}
186	cpufreq_frequency_table_put_attr(policy->cpu);
187	return 0;
188}
189
190static unsigned int powernow_k6_get(unsigned int cpu)
191{
192	unsigned int ret;
193	ret = (busfreq * powernow_k6_get_cpu_multiplier());
194	return ret;
195}
196
197static struct freq_attr *powernow_k6_attr[] = {
198	&cpufreq_freq_attr_scaling_available_freqs,
199	NULL,
200};
201
202static struct cpufreq_driver powernow_k6_driver = {
203	.verify		= powernow_k6_verify,
204	.target		= powernow_k6_target,
205	.init		= powernow_k6_cpu_init,
206	.exit		= powernow_k6_cpu_exit,
207	.get		= powernow_k6_get,
208	.name		= "powernow-k6",
209	.owner		= THIS_MODULE,
210	.attr		= powernow_k6_attr,
211};
212
213
214/**
215 * powernow_k6_init - initializes the k6 PowerNow! CPUFreq driver
216 *
217 *   Initializes the K6 PowerNow! support. Returns -ENODEV on unsupported
218 * devices, -EINVAL or -ENOMEM on problems during initiatization, and zero
219 * on success.
220 */
221static int __init powernow_k6_init(void)
222{
223	struct cpuinfo_x86 *c = &cpu_data(0);
224
225	if ((c->x86_vendor != X86_VENDOR_AMD) || (c->x86 != 5) ||
226		((c->x86_model != 12) && (c->x86_model != 13)))
227		return -ENODEV;
228
229	if (!request_region(POWERNOW_IOPORT, 16, "PowerNow!")) {
230		printk(KERN_INFO PFX "PowerNow IOPORT region already used.\n");
231		return -EIO;
232	}
233
234	if (cpufreq_register_driver(&powernow_k6_driver)) {
235		release_region(POWERNOW_IOPORT, 16);
236		return -EINVAL;
237	}
238
239	return 0;
240}
241
242
243/**
244 * powernow_k6_exit - unregisters AMD K6-2+/3+ PowerNow! support
245 *
246 *   Unregisters AMD K6-2+ / K6-3+ PowerNow! support.
247 */
248static void __exit powernow_k6_exit(void)
249{
250	cpufreq_unregister_driver(&powernow_k6_driver);
251	release_region(POWERNOW_IOPORT, 16);
252}
253
254
255MODULE_AUTHOR("Arjan van de Ven, Dave Jones <davej@redhat.com>, "
256		"Dominik Brodowski <linux@brodo.de>");
257MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
258MODULE_LICENSE("GPL");
259
260module_init(powernow_k6_init);
261module_exit(powernow_k6_exit);
262