2 * Pentium 4/Xeon CPU on demand clock modulation/speed scaling
3 * (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
4 * (C) 2002 Zwane Mwaikambo <zwane@commfireservices.com>
5 * (C) 2002 Arjan van de Ven <arjanv@redhat.com>
6 * (C) 2002 Tora T. Engstad
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
14 * The author(s) of this software shall not be held liable for damages
15 * of any nature resulting due to the use of this software. This
16 * software is provided AS-IS with no warranties.
18 * Date Errata Description
19 * 20020525 N44, O17 12.5% or 25% DC causes lockup
23 #include <linux/config.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/init.h>
27 #include <linux/smp.h>
28 #include <linux/cpufreq.h>
29 #include <linux/slab.h>
30 #include <linux/sched.h>
32 #include <asm/processor.h>
34 #include <asm/timex.h>
36 #include "speedstep-lib.h"
38 #define PFX "cpufreq: "
41 * Duty Cycle (3bits), note DC_DISABLE is not specified in
42 * intel docs i just use it to mean disable
45 DC_RESV, DC_DFLT, DC_25PT, DC_38PT, DC_50PT,
46 DC_64PT, DC_75PT, DC_88PT, DC_DISABLE
52 static int has_N44_O17_errata[NR_CPUS];
53 static unsigned int stock_freq;
55 static int cpufreq_p4_setdc(unsigned int cpu, unsigned int newstate)
58 cpumask_t cpus_allowed, affected_cpu_map;
59 struct cpufreq_freqs freqs;
60 int hyperthreading = 0;
63 if (!cpu_online(cpu) || (newstate > DC_DISABLE) ||
64 (newstate == DC_RESV))
67 /* switch to physical CPU where state is to be changed*/
68 cpus_allowed = current->cpus_allowed;
70 /* only run on CPU to be set, or on its sibling */
71 affected_cpu_map = cpumask_of_cpu(cpu);
73 hyperthreading = ((cpu_has_ht) && (smp_num_siblings == 2));
75 sibling = cpu_sibling_map[cpu];
76 cpu_set(sibling, affected_cpu_map);
79 set_cpus_allowed(current, affected_cpu_map);
80 BUG_ON(!cpu_isset(smp_processor_id(), affected_cpu_map));
82 /* get current state */
83 rdmsr(MSR_IA32_THERM_CONTROL, l, h);
91 set_cpus_allowed(current, cpus_allowed);
93 } else if (l == DC_RESV) {
94 printk(KERN_ERR PFX "BIG FAT WARNING: currently in invalid setting\n");
98 freqs.old = stock_freq * l / 8;
99 freqs.new = stock_freq * newstate / 8;
101 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
102 if (hyperthreading) {
104 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
107 rdmsr(MSR_IA32_THERM_STATUS, l, h);
110 printk(KERN_DEBUG PFX "CPU#%d currently thermal throttled\n", cpu);
112 if (has_N44_O17_errata[cpu] && (newstate == DC_25PT || newstate == DC_DFLT))
115 rdmsr(MSR_IA32_THERM_CONTROL, l, h);
116 if (newstate == DC_DISABLE) {
117 /* printk(KERN_INFO PFX "CPU#%d disabling modulation\n", cpu); */
118 wrmsr(MSR_IA32_THERM_CONTROL, l & ~(1<<4), h);
120 /* printk(KERN_INFO PFX "CPU#%d setting duty cycle to %d%%\n",
121 cpu, ((125 * newstate) / 10)); */
122 /* bits 63 - 5 : reserved
123 * bit 4 : enable/disable
124 * bits 3-1 : duty cycle
128 l = l | (1<<4) | ((newstate & 0x7)<<1);
129 wrmsr(MSR_IA32_THERM_CONTROL, l, h);
132 set_cpus_allowed(current, cpus_allowed);
135 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
136 if (hyperthreading) {
138 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
145 static struct cpufreq_frequency_table p4clockmod_table[] = {
146 {DC_RESV, CPUFREQ_ENTRY_INVALID},
155 {DC_RESV, CPUFREQ_TABLE_END},
159 static int cpufreq_p4_target(struct cpufreq_policy *policy,
160 unsigned int target_freq,
161 unsigned int relation)
163 unsigned int newstate = DC_RESV;
165 if (cpufreq_frequency_table_target(policy, &p4clockmod_table[0], target_freq, relation, &newstate))
168 cpufreq_p4_setdc(policy->cpu, p4clockmod_table[newstate].index);
174 static int cpufreq_p4_verify(struct cpufreq_policy *policy)
176 return cpufreq_frequency_table_verify(policy, &p4clockmod_table[0]);
180 static unsigned int cpufreq_p4_get_frequency(struct cpuinfo_x86 *c)
182 if ((c->x86 == 0x06) && (c->x86_model == 0x09)) {
184 printk(KERN_WARNING PFX "Warning: Pentium M detected. "
185 "The speedstep_centrino module offers voltage scaling"
186 " in addition of frequency scaling. You should use "
187 "that instead of p4-clockmod, if possible.\n");
188 return speedstep_get_processor_frequency(SPEEDSTEP_PROCESSOR_PM);
192 printk(KERN_WARNING PFX "Unknown p4-clockmod-capable CPU. Please send an e-mail to <linux@brodo.de>\n");
196 if (speedstep_detect_processor() == SPEEDSTEP_PROCESSOR_P4M) {
197 printk(KERN_WARNING PFX "Warning: Pentium 4-M detected. "
198 "The speedstep-ich or acpi cpufreq modules offer "
199 "voltage scaling in addition of frequency scaling. "
200 "You should use either one instead of p4-clockmod, "
202 return speedstep_get_processor_frequency(SPEEDSTEP_PROCESSOR_P4M);
205 return speedstep_get_processor_frequency(SPEEDSTEP_PROCESSOR_P4D);
210 static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
212 struct cpuinfo_x86 *c = &cpu_data[policy->cpu];
216 /* Errata workaround */
217 cpuid = (c->x86 << 8) | (c->x86_model << 4) | c->x86_mask;
223 has_N44_O17_errata[policy->cpu] = 1;
226 /* get max frequency */
227 stock_freq = cpufreq_p4_get_frequency(c);
232 for (i=1; (p4clockmod_table[i].frequency != CPUFREQ_TABLE_END); i++) {
233 if ((i<2) && (has_N44_O17_errata[policy->cpu]))
234 p4clockmod_table[i].frequency = CPUFREQ_ENTRY_INVALID;
236 p4clockmod_table[i].frequency = (stock_freq * i)/8;
238 cpufreq_frequency_table_get_attr(p4clockmod_table, policy->cpu);
240 /* cpuinfo and default policy values */
241 policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
242 policy->cpuinfo.transition_latency = 1000000; /* assumed */
243 policy->cur = stock_freq;
245 return cpufreq_frequency_table_cpuinfo(policy, &p4clockmod_table[0]);
249 static int cpufreq_p4_cpu_exit(struct cpufreq_policy *policy)
251 cpufreq_frequency_table_put_attr(policy->cpu);
255 static struct freq_attr* p4clockmod_attr[] = {
256 &cpufreq_freq_attr_scaling_available_freqs,
260 static struct cpufreq_driver p4clockmod_driver = {
261 .verify = cpufreq_p4_verify,
262 .target = cpufreq_p4_target,
263 .init = cpufreq_p4_cpu_init,
264 .exit = cpufreq_p4_cpu_exit,
265 .name = "p4-clockmod",
266 .owner = THIS_MODULE,
267 .attr = p4clockmod_attr,
271 static int __init cpufreq_p4_init(void)
273 struct cpuinfo_x86 *c = cpu_data;
276 * THERM_CONTROL is architectural for IA32 now, so
277 * we can rely on the capability checks
279 if (c->x86_vendor != X86_VENDOR_INTEL)
282 if (!test_bit(X86_FEATURE_ACPI, c->x86_capability) ||
283 !test_bit(X86_FEATURE_ACC, c->x86_capability))
286 printk(KERN_INFO PFX "P4/Xeon(TM) CPU On-Demand Clock Modulation available\n");
288 return cpufreq_register_driver(&p4clockmod_driver);
292 static void __exit cpufreq_p4_exit(void)
294 cpufreq_unregister_driver(&p4clockmod_driver);
298 MODULE_AUTHOR ("Zwane Mwaikambo <zwane@commfireservices.com>");
299 MODULE_DESCRIPTION ("cpufreq driver for Pentium(TM) 4/Xeon(TM)");
300 MODULE_LICENSE ("GPL");
302 late_initcall(cpufreq_p4_init);
303 module_exit(cpufreq_p4_exit);