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/cpumask.h>
31 #include <linux/sched.h> /* current / set_cpus_allowed() */
33 #include <asm/processor.h>
35 #include <asm/timex.h>
37 #include "speedstep-lib.h"
39 #define PFX "p4-clockmod: "
40 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "p4-clockmod", msg)
43 * Duty Cycle (3bits), note DC_DISABLE is not specified in
44 * intel docs i just use it to mean disable
47 DC_RESV
, DC_DFLT
, DC_25PT
, DC_38PT
, DC_50PT
,
48 DC_64PT
, DC_75PT
, DC_88PT
, DC_DISABLE
54 static int has_N44_O17_errata
[NR_CPUS
];
55 static unsigned int stock_freq
;
56 static struct cpufreq_driver p4clockmod_driver
;
57 static unsigned int cpufreq_p4_get(unsigned int cpu
);
59 static int cpufreq_p4_setdc(unsigned int cpu
, unsigned int newstate
)
63 if (!cpu_online(cpu
) || (newstate
> DC_DISABLE
) || (newstate
== DC_RESV
))
66 rdmsr(MSR_IA32_THERM_STATUS
, l
, h
);
69 dprintk("CPU#%d currently thermal throttled\n", cpu
);
71 if (has_N44_O17_errata
[cpu
] && (newstate
== DC_25PT
|| newstate
== DC_DFLT
))
74 rdmsr(MSR_IA32_THERM_CONTROL
, l
, h
);
75 if (newstate
== DC_DISABLE
) {
76 dprintk("CPU#%d disabling modulation\n", cpu
);
77 wrmsr(MSR_IA32_THERM_CONTROL
, l
& ~(1<<4), h
);
79 dprintk("CPU#%d setting duty cycle to %d%%\n",
80 cpu
, ((125 * newstate
) / 10));
81 /* bits 63 - 5 : reserved
82 * bit 4 : enable/disable
83 * bits 3-1 : duty cycle
87 l
= l
| (1<<4) | ((newstate
& 0x7)<<1);
88 wrmsr(MSR_IA32_THERM_CONTROL
, l
, h
);
95 static struct cpufreq_frequency_table p4clockmod_table
[] = {
96 {DC_RESV
, CPUFREQ_ENTRY_INVALID
},
105 {DC_RESV
, CPUFREQ_TABLE_END
},
109 static int cpufreq_p4_target(struct cpufreq_policy
*policy
,
110 unsigned int target_freq
,
111 unsigned int relation
)
113 unsigned int newstate
= DC_RESV
;
114 struct cpufreq_freqs freqs
;
115 cpumask_t cpus_allowed
;
118 if (cpufreq_frequency_table_target(policy
, &p4clockmod_table
[0], target_freq
, relation
, &newstate
))
121 freqs
.old
= cpufreq_p4_get(policy
->cpu
);
122 freqs
.new = stock_freq
* p4clockmod_table
[newstate
].index
/ 8;
124 if (freqs
.new == freqs
.old
)
128 for_each_cpu_mask(i
, policy
->cpus
) {
130 cpufreq_notify_transition(&freqs
, CPUFREQ_PRECHANGE
);
133 /* run on each logical CPU, see section 13.15.3 of IA32 Intel Architecture Software
134 * Developer's Manual, Volume 3
136 cpus_allowed
= current
->cpus_allowed
;
138 for_each_cpu_mask(i
, policy
->cpus
) {
139 cpumask_t this_cpu
= cpumask_of_cpu(i
);
141 set_cpus_allowed(current
, this_cpu
);
142 BUG_ON(smp_processor_id() != i
);
144 cpufreq_p4_setdc(i
, p4clockmod_table
[newstate
].index
);
146 set_cpus_allowed(current
, cpus_allowed
);
149 for_each_cpu_mask(i
, policy
->cpus
) {
151 cpufreq_notify_transition(&freqs
, CPUFREQ_POSTCHANGE
);
158 static int cpufreq_p4_verify(struct cpufreq_policy
*policy
)
160 return cpufreq_frequency_table_verify(policy
, &p4clockmod_table
[0]);
164 static unsigned int cpufreq_p4_get_frequency(struct cpuinfo_x86
*c
)
166 if ((c
->x86
== 0x06) && (c
->x86_model
== 0x09)) {
167 /* Pentium M (Banias) */
168 printk(KERN_WARNING PFX
"Warning: Pentium M detected. "
169 "The speedstep_centrino module offers voltage scaling"
170 " in addition of frequency scaling. You should use "
171 "that instead of p4-clockmod, if possible.\n");
172 return speedstep_get_processor_frequency(SPEEDSTEP_PROCESSOR_PM
);
175 if ((c
->x86
== 0x06) && (c
->x86_model
== 0x0D)) {
176 /* Pentium M (Dothan) */
177 printk(KERN_WARNING PFX
"Warning: Pentium M detected. "
178 "The speedstep_centrino module offers voltage scaling"
179 " in addition of frequency scaling. You should use "
180 "that instead of p4-clockmod, if possible.\n");
181 /* on P-4s, the TSC runs with constant frequency independent whether
182 * throttling is active or not. */
183 p4clockmod_driver
.flags
|= CPUFREQ_CONST_LOOPS
;
184 return speedstep_get_processor_frequency(SPEEDSTEP_PROCESSOR_PM
);
188 printk(KERN_WARNING PFX
"Unknown p4-clockmod-capable CPU. Please send an e-mail to <linux@brodo.de>\n");
192 /* on P-4s, the TSC runs with constant frequency independent whether
193 * throttling is active or not. */
194 p4clockmod_driver
.flags
|= CPUFREQ_CONST_LOOPS
;
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
];
217 policy
->cpus
= cpu_sibling_map
[policy
->cpu
];
220 /* Errata workaround */
221 cpuid
= (c
->x86
<< 8) | (c
->x86_model
<< 4) | c
->x86_mask
;
227 has_N44_O17_errata
[policy
->cpu
] = 1;
228 dprintk("has errata -- disabling low frequencies\n");
231 /* get max frequency */
232 stock_freq
= cpufreq_p4_get_frequency(c
);
237 for (i
=1; (p4clockmod_table
[i
].frequency
!= CPUFREQ_TABLE_END
); i
++) {
238 if ((i
<2) && (has_N44_O17_errata
[policy
->cpu
]))
239 p4clockmod_table
[i
].frequency
= CPUFREQ_ENTRY_INVALID
;
241 p4clockmod_table
[i
].frequency
= (stock_freq
* i
)/8;
243 cpufreq_frequency_table_get_attr(p4clockmod_table
, policy
->cpu
);
245 /* cpuinfo and default policy values */
246 policy
->governor
= CPUFREQ_DEFAULT_GOVERNOR
;
247 policy
->cpuinfo
.transition_latency
= 1000000; /* assumed */
248 policy
->cur
= stock_freq
;
250 return cpufreq_frequency_table_cpuinfo(policy
, &p4clockmod_table
[0]);
254 static int cpufreq_p4_cpu_exit(struct cpufreq_policy
*policy
)
256 cpufreq_frequency_table_put_attr(policy
->cpu
);
260 static unsigned int cpufreq_p4_get(unsigned int cpu
)
262 cpumask_t cpus_allowed
;
265 cpus_allowed
= current
->cpus_allowed
;
267 set_cpus_allowed(current
, cpumask_of_cpu(cpu
));
268 BUG_ON(smp_processor_id() != cpu
);
270 rdmsr(MSR_IA32_THERM_CONTROL
, l
, h
);
272 set_cpus_allowed(current
, cpus_allowed
);
281 return (stock_freq
* l
/ 8);
286 static struct freq_attr
* p4clockmod_attr
[] = {
287 &cpufreq_freq_attr_scaling_available_freqs
,
291 static struct cpufreq_driver p4clockmod_driver
= {
292 .verify
= cpufreq_p4_verify
,
293 .target
= cpufreq_p4_target
,
294 .init
= cpufreq_p4_cpu_init
,
295 .exit
= cpufreq_p4_cpu_exit
,
296 .get
= cpufreq_p4_get
,
297 .name
= "p4-clockmod",
298 .owner
= THIS_MODULE
,
299 .attr
= p4clockmod_attr
,
303 static int __init
cpufreq_p4_init(void)
305 struct cpuinfo_x86
*c
= cpu_data
;
309 * THERM_CONTROL is architectural for IA32 now, so
310 * we can rely on the capability checks
312 if (c
->x86_vendor
!= X86_VENDOR_INTEL
)
315 if (!test_bit(X86_FEATURE_ACPI
, c
->x86_capability
) ||
316 !test_bit(X86_FEATURE_ACC
, c
->x86_capability
))
319 ret
= cpufreq_register_driver(&p4clockmod_driver
);
321 printk(KERN_INFO PFX
"P4/Xeon(TM) CPU On-Demand Clock Modulation available\n");
327 static void __exit
cpufreq_p4_exit(void)
329 cpufreq_unregister_driver(&p4clockmod_driver
);
333 MODULE_AUTHOR ("Zwane Mwaikambo <zwane@commfireservices.com>");
334 MODULE_DESCRIPTION ("cpufreq driver for Pentium(TM) 4/Xeon(TM)");
335 MODULE_LICENSE ("GPL");
337 late_initcall(cpufreq_p4_init
);
338 module_exit(cpufreq_p4_exit
);