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,
6 * Licensed under the terms of the GNU GPL License version 2.
8 * BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
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>
19 #include <asm/cpu_device_id.h>
22 #define POWERNOW_IOPORT 0xfff0 /* it doesn't matter where, as long
25 #define PFX "powernow-k6: "
26 static unsigned int busfreq; /* FSB, in 10 kHz */
27 static unsigned int max_multiplier;
29 static unsigned int param_busfreq = 0;
30 static unsigned int param_max_multiplier = 0;
32 module_param_named(max_multiplier, param_max_multiplier, uint, S_IRUGO);
33 MODULE_PARM_DESC(max_multiplier, "Maximum multiplier (allowed values: 20 30 35 40 45 50 55 60)");
35 module_param_named(bus_frequency, param_busfreq, uint, S_IRUGO);
36 MODULE_PARM_DESC(bus_frequency, "Bus frequency in kHz");
38 /* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
39 static struct cpufreq_frequency_table clock_ratio[] = {
40 {45, /* 000 -> 4.5x */ 0},
41 {50, /* 001 -> 5.0x */ 0},
42 {40, /* 010 -> 4.0x */ 0},
43 {55, /* 011 -> 5.5x */ 0},
44 {20, /* 100 -> 2.0x */ 0},
45 {30, /* 101 -> 3.0x */ 0},
46 {60, /* 110 -> 6.0x */ 0},
47 {35, /* 111 -> 3.5x */ 0},
48 {0, CPUFREQ_TABLE_END}
54 } usual_frequency_table[] = {
55 { 400000, 40 }, // 100 * 4
56 { 450000, 45 }, // 100 * 4.5
57 { 475000, 50 }, // 95 * 5
58 { 500000, 50 }, // 100 * 5
59 { 506250, 45 }, // 112.5 * 4.5
60 { 533500, 55 }, // 97 * 5.5
61 { 550000, 55 }, // 100 * 5.5
62 { 562500, 50 }, // 112.5 * 5
63 { 570000, 60 }, // 95 * 6
64 { 600000, 60 }, // 100 * 6
65 { 618750, 55 }, // 112.5 * 5.5
66 { 660000, 55 }, // 120 * 5.5
67 { 675000, 60 }, // 112.5 * 6
68 { 720000, 60 }, // 120 * 6
71 #define FREQ_RANGE 3000
74 * powernow_k6_get_cpu_multiplier - returns the current FSB multiplier
76 * Returns the current setting of the frequency multiplier. Core clock
77 * speed is frequency of the Front-Side Bus multiplied with this value.
79 static int powernow_k6_get_cpu_multiplier(void)
81 unsigned long invalue = 0;
86 msrval = POWERNOW_IOPORT + 0x1;
87 wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
88 invalue = inl(POWERNOW_IOPORT + 0x8);
89 msrval = POWERNOW_IOPORT + 0x0;
90 wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
94 return clock_ratio[(invalue >> 5)&7].driver_data;
97 static void powernow_k6_set_cpu_multiplier(unsigned int best_i)
99 unsigned long outvalue, invalue;
100 unsigned long msrval;
103 /* we now need to transform best_i to the BVC format, see AMD#23446 */
106 * The processor doesn't respond to inquiry cycles while changing the
107 * frequency, so we must disable cache.
111 write_cr0(cr0 | X86_CR0_CD);
114 outvalue = (1<<12) | (1<<10) | (1<<9) | (best_i<<5);
116 msrval = POWERNOW_IOPORT + 0x1;
117 wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
118 invalue = inl(POWERNOW_IOPORT + 0x8);
119 invalue = invalue & 0x1f;
120 outvalue = outvalue | invalue;
121 outl(outvalue, (POWERNOW_IOPORT + 0x8));
122 msrval = POWERNOW_IOPORT + 0x0;
123 wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
130 * powernow_k6_target - set the PowerNow! multiplier
131 * @best_i: clock_ratio[best_i] is the target multiplier
133 * Tries to change the PowerNow! multiplier
135 static int powernow_k6_target(struct cpufreq_policy *policy,
138 struct cpufreq_freqs freqs;
140 if (clock_ratio[best_i].driver_data > max_multiplier) {
141 printk(KERN_ERR PFX "invalid target frequency\n");
145 freqs.old = busfreq * powernow_k6_get_cpu_multiplier();
146 freqs.new = busfreq * clock_ratio[best_i].driver_data;
148 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
150 powernow_k6_set_cpu_multiplier(best_i);
152 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
157 static int powernow_k6_cpu_init(struct cpufreq_policy *policy)
162 if (policy->cpu != 0)
167 for (i = 0; i < ARRAY_SIZE(usual_frequency_table); i++) {
168 if (khz >= usual_frequency_table[i].freq - FREQ_RANGE &&
169 khz <= usual_frequency_table[i].freq + FREQ_RANGE) {
170 khz = usual_frequency_table[i].freq;
171 max_multiplier = usual_frequency_table[i].mult;
175 if (param_max_multiplier) {
176 for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
177 if (clock_ratio[i].driver_data == param_max_multiplier) {
178 max_multiplier = param_max_multiplier;
179 goto have_max_multiplier;
182 printk(KERN_ERR "powernow-k6: invalid max_multiplier parameter, valid parameters 20, 30, 35, 40, 45, 50, 55, 60\n");
186 if (!max_multiplier) {
187 printk(KERN_WARNING "powernow-k6: unknown frequency %u, cannot determine current multiplier\n", khz);
188 printk(KERN_WARNING "powernow-k6: use module parameters max_multiplier and bus_frequency\n");
193 param_max_multiplier = max_multiplier;
196 if (param_busfreq >= 50000 && param_busfreq <= 150000) {
197 busfreq = param_busfreq / 10;
200 printk(KERN_ERR "powernow-k6: invalid bus_frequency parameter, allowed range 50000 - 150000 kHz\n");
204 busfreq = khz / max_multiplier;
206 param_busfreq = busfreq * 10;
209 for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
210 f = clock_ratio[i].driver_data;
211 if (f > max_multiplier)
212 clock_ratio[i].frequency = CPUFREQ_ENTRY_INVALID;
214 clock_ratio[i].frequency = busfreq * f;
217 /* cpuinfo and default policy values */
218 policy->cpuinfo.transition_latency = 500000;
220 return cpufreq_table_validate_and_show(policy, clock_ratio);
224 static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
227 for (i = 0; i < 8; i++) {
228 if (i == max_multiplier)
229 powernow_k6_target(policy, i);
231 cpufreq_frequency_table_put_attr(policy->cpu);
235 static unsigned int powernow_k6_get(unsigned int cpu)
238 ret = (busfreq * powernow_k6_get_cpu_multiplier());
242 static struct cpufreq_driver powernow_k6_driver = {
243 .verify = cpufreq_generic_frequency_table_verify,
244 .target_index = powernow_k6_target,
245 .init = powernow_k6_cpu_init,
246 .exit = powernow_k6_cpu_exit,
247 .get = powernow_k6_get,
248 .name = "powernow-k6",
249 .attr = cpufreq_generic_attr,
252 static const struct x86_cpu_id powernow_k6_ids[] = {
253 { X86_VENDOR_AMD, 5, 12 },
254 { X86_VENDOR_AMD, 5, 13 },
257 MODULE_DEVICE_TABLE(x86cpu, powernow_k6_ids);
260 * powernow_k6_init - initializes the k6 PowerNow! CPUFreq driver
262 * Initializes the K6 PowerNow! support. Returns -ENODEV on unsupported
263 * devices, -EINVAL or -ENOMEM on problems during initiatization, and zero
266 static int __init powernow_k6_init(void)
268 if (!x86_match_cpu(powernow_k6_ids))
271 if (!request_region(POWERNOW_IOPORT, 16, "PowerNow!")) {
272 printk(KERN_INFO PFX "PowerNow IOPORT region already used.\n");
276 if (cpufreq_register_driver(&powernow_k6_driver)) {
277 release_region(POWERNOW_IOPORT, 16);
286 * powernow_k6_exit - unregisters AMD K6-2+/3+ PowerNow! support
288 * Unregisters AMD K6-2+ / K6-3+ PowerNow! support.
290 static void __exit powernow_k6_exit(void)
292 cpufreq_unregister_driver(&powernow_k6_driver);
293 release_region(POWERNOW_IOPORT, 16);
297 MODULE_AUTHOR("Arjan van de Ven, Dave Jones <davej@redhat.com>, "
298 "Dominik Brodowski <linux@brodo.de>");
299 MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
300 MODULE_LICENSE("GPL");
302 module_init(powernow_k6_init);
303 module_exit(powernow_k6_exit);