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>
31 #include <asm/processor.h>
33 #include <asm/timex.h>
35 #include "speedstep-lib.h"
37 #define PFX "p4-clockmod: "
40 * Duty Cycle (3bits), note DC_DISABLE is not specified in
41 * intel docs i just use it to mean disable
44 DC_RESV, DC_DFLT, DC_25PT, DC_38PT, DC_50PT,
45 DC_64PT, DC_75PT, DC_88PT, DC_DISABLE
51 static int has_N44_O17_errata[NR_CPUS];
52 static unsigned int stock_freq;
53 static struct cpufreq_driver p4clockmod_driver;
54 static unsigned int cpufreq_p4_get(unsigned int cpu);
56 static int cpufreq_p4_setdc(unsigned int cpu, unsigned int newstate)
60 if (!cpu_online(cpu) || (newstate > DC_DISABLE) || (newstate == DC_RESV))
63 rdmsr(MSR_IA32_THERM_STATUS, l, h);
66 printk(KERN_DEBUG PFX "CPU#%d currently thermal throttled\n", cpu);
68 if (has_N44_O17_errata[cpu] && (newstate == DC_25PT || newstate == DC_DFLT))
71 rdmsr(MSR_IA32_THERM_CONTROL, l, h);
72 if (newstate == DC_DISABLE) {
73 /* printk(KERN_INFO PFX "CPU#%d disabling modulation\n", cpu); */
74 wrmsr(MSR_IA32_THERM_CONTROL, l & ~(1<<4), h);
76 /* printk(KERN_INFO PFX "CPU#%d setting duty cycle to %d%%\n",
77 cpu, ((125 * newstate) / 10)); */
78 /* bits 63 - 5 : reserved
79 * bit 4 : enable/disable
80 * bits 3-1 : duty cycle
84 l = l | (1<<4) | ((newstate & 0x7)<<1);
85 wrmsr(MSR_IA32_THERM_CONTROL, l, h);
92 static struct cpufreq_frequency_table p4clockmod_table[] = {
93 {DC_RESV, CPUFREQ_ENTRY_INVALID},
102 {DC_RESV, CPUFREQ_TABLE_END},
106 static int cpufreq_p4_target(struct cpufreq_policy *policy,
107 unsigned int target_freq,
108 unsigned int relation)
110 unsigned int newstate = DC_RESV;
111 struct cpufreq_freqs freqs;
112 cpumask_t cpus_allowed, affected_cpu_map;
115 if (cpufreq_frequency_table_target(policy, &p4clockmod_table[0], target_freq, relation, &newstate))
118 freqs.old = cpufreq_p4_get(policy->cpu);
119 freqs.new = stock_freq * p4clockmod_table[newstate].index / 8;
121 if (freqs.new == freqs.old)
124 /* switch to physical CPU where state is to be changed*/
125 cpus_allowed = current->cpus_allowed;
127 /* only run on CPU to be set, or on its sibling */
129 affected_cpu_map = cpu_sibling_map[policy->cpu];
131 affected_cpu_map = cpumask_of_cpu(policy->cpu);
136 if (cpu_isset(i, affected_cpu_map)) {
138 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
142 /* run on each logical CPU, see section 13.15.3 of IA32 Intel Architecture Software
143 * Developer's Manual, Volume 3
146 if (cpu_isset(i, affected_cpu_map)) {
147 cpumask_t this_cpu = cpumask_of_cpu(i);
149 set_cpus_allowed(current, this_cpu);
150 BUG_ON(smp_processor_id() != i);
152 cpufreq_p4_setdc(i, p4clockmod_table[newstate].index);
155 set_cpus_allowed(current, cpus_allowed);
159 if (cpu_isset(i, affected_cpu_map)) {
161 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
169 static int cpufreq_p4_verify(struct cpufreq_policy *policy)
171 return cpufreq_frequency_table_verify(policy, &p4clockmod_table[0]);
175 static unsigned int cpufreq_p4_get_frequency(struct cpuinfo_x86 *c)
177 if ((c->x86 == 0x06) && (c->x86_model == 0x09)) {
178 /* Pentium M (Banias) */
179 printk(KERN_WARNING PFX "Warning: Pentium M detected. "
180 "The speedstep_centrino module offers voltage scaling"
181 " in addition of frequency scaling. You should use "
182 "that instead of p4-clockmod, if possible.\n");
183 return speedstep_get_processor_frequency(SPEEDSTEP_PROCESSOR_PM);
186 if ((c->x86 == 0x06) && (c->x86_model == 0x13)) {
187 /* Pentium M (Dothan) */
188 printk(KERN_WARNING PFX "Warning: Pentium M detected. "
189 "The speedstep_centrino module offers voltage scaling"
190 " in addition of frequency scaling. You should use "
191 "that instead of p4-clockmod, if possible.\n");
192 /* on P-4s, the TSC runs with constant frequency independent wether
193 * throttling is active or not. */
194 p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS;
195 return speedstep_get_processor_frequency(SPEEDSTEP_PROCESSOR_PM);
199 printk(KERN_WARNING PFX "Unknown p4-clockmod-capable CPU. Please send an e-mail to <linux@brodo.de>\n");
203 /* on P-4s, the TSC runs with constant frequency independent wether
204 * throttling is active or not. */
205 p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS;
207 if (speedstep_detect_processor() == SPEEDSTEP_PROCESSOR_P4M) {
208 printk(KERN_WARNING PFX "Warning: Pentium 4-M detected. "
209 "The speedstep-ich or acpi cpufreq modules offer "
210 "voltage scaling in addition of frequency scaling. "
211 "You should use either one instead of p4-clockmod, "
213 return speedstep_get_processor_frequency(SPEEDSTEP_PROCESSOR_P4M);
216 return speedstep_get_processor_frequency(SPEEDSTEP_PROCESSOR_P4D);
221 static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
223 struct cpuinfo_x86 *c = &cpu_data[policy->cpu];
227 /* Errata workaround */
228 cpuid = (c->x86 << 8) | (c->x86_model << 4) | c->x86_mask;
234 has_N44_O17_errata[policy->cpu] = 1;
237 /* get max frequency */
238 stock_freq = cpufreq_p4_get_frequency(c);
243 for (i=1; (p4clockmod_table[i].frequency != CPUFREQ_TABLE_END); i++) {
244 if ((i<2) && (has_N44_O17_errata[policy->cpu]))
245 p4clockmod_table[i].frequency = CPUFREQ_ENTRY_INVALID;
247 p4clockmod_table[i].frequency = (stock_freq * i)/8;
249 cpufreq_frequency_table_get_attr(p4clockmod_table, policy->cpu);
251 /* cpuinfo and default policy values */
252 policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
253 policy->cpuinfo.transition_latency = 1000000; /* assumed */
254 policy->cur = stock_freq;
256 return cpufreq_frequency_table_cpuinfo(policy, &p4clockmod_table[0]);
260 static int cpufreq_p4_cpu_exit(struct cpufreq_policy *policy)
262 cpufreq_frequency_table_put_attr(policy->cpu);
266 static unsigned int cpufreq_p4_get(unsigned int cpu)
268 cpumask_t cpus_allowed, affected_cpu_map;
271 cpus_allowed = current->cpus_allowed;
272 affected_cpu_map = cpumask_of_cpu(cpu);
274 set_cpus_allowed(current, affected_cpu_map);
275 BUG_ON(!cpu_isset(smp_processor_id(), affected_cpu_map));
277 rdmsr(MSR_IA32_THERM_CONTROL, l, h);
279 set_cpus_allowed(current, cpus_allowed);
288 return (stock_freq * l / 8);
293 static struct freq_attr* p4clockmod_attr[] = {
294 &cpufreq_freq_attr_scaling_available_freqs,
298 static struct cpufreq_driver p4clockmod_driver = {
299 .verify = cpufreq_p4_verify,
300 .target = cpufreq_p4_target,
301 .init = cpufreq_p4_cpu_init,
302 .exit = cpufreq_p4_cpu_exit,
303 .get = cpufreq_p4_get,
304 .name = "p4-clockmod",
305 .owner = THIS_MODULE,
306 .attr = p4clockmod_attr,
310 static int __init cpufreq_p4_init(void)
312 struct cpuinfo_x86 *c = cpu_data;
315 * THERM_CONTROL is architectural for IA32 now, so
316 * we can rely on the capability checks
318 if (c->x86_vendor != X86_VENDOR_INTEL)
321 if (!test_bit(X86_FEATURE_ACPI, c->x86_capability) ||
322 !test_bit(X86_FEATURE_ACC, c->x86_capability))
325 printk(KERN_INFO PFX "P4/Xeon(TM) CPU On-Demand Clock Modulation available\n");
327 return cpufreq_register_driver(&p4clockmod_driver);
331 static void __exit cpufreq_p4_exit(void)
333 cpufreq_unregister_driver(&p4clockmod_driver);
337 MODULE_AUTHOR ("Zwane Mwaikambo <zwane@commfireservices.com>");
338 MODULE_DESCRIPTION ("cpufreq driver for Pentium(TM) 4/Xeon(TM)");
339 MODULE_LICENSE ("GPL");
341 late_initcall(cpufreq_p4_init);
342 module_exit(cpufreq_p4_exit);