drivers/cpufreq/p4-clockmod.c

   1 /*
   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
   7  *      All Rights Reserved
   8  *
   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.
  13  *
  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.
  17  *
  18  *      Date            Errata                  Description
  19  *      20020525        N44, O17        12.5% or 25% DC causes lockup
  20  *
  21  */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/init.h>
  26 #include <linux/smp.h>
  27 #include <linux/cpufreq.h>
  28 #include <linux/cpumask.h>
  29 #include <linux/timex.h>
  30
  31 #include <asm/processor.h>
  32 #include <asm/msr.h>
  33 #include <asm/timer.h>
  34 #include <asm/cpu_device_id.h>
  35
  36 #include "speedstep-lib.h"
  37
  38 #define PFX     "p4-clockmod: "
  39
  40 /*
  41  * Duty Cycle (3bits), note DC_DISABLE is not specified in
  42  * intel docs i just use it to mean disable
  43  */
  44 enum {
  45         DC_RESV, DC_DFLT, DC_25PT, DC_38PT, DC_50PT,
  46         DC_64PT, DC_75PT, DC_88PT, DC_DISABLE
  47 };
  48
  49 #define DC_ENTRIES      8
  50
  51
  52 static int has_N44_O17_errata[NR_CPUS];
  53 static unsigned int stock_freq;
  54 static struct cpufreq_driver p4clockmod_driver;
  55 static unsigned int cpufreq_p4_get(unsigned int cpu);
  56
  57 static int cpufreq_p4_setdc(unsigned int cpu, unsigned int newstate)
  58 {
  59         u32 l, h;
  60
  61         if ((newstate > DC_DISABLE) || (newstate == DC_RESV))
  62                 return -EINVAL;
  63
  64         rdmsr_on_cpu(cpu, MSR_IA32_THERM_STATUS, &l, &h);
  65
  66         if (l & 0x01)
  67                 pr_debug("CPU#%d currently thermal throttled\n", cpu);
  68
  69         if (has_N44_O17_errata[cpu] &&
  70             (newstate == DC_25PT || newstate == DC_DFLT))
  71                 newstate = DC_38PT;
  72
  73         rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, &l, &h);
  74         if (newstate == DC_DISABLE) {
  75                 pr_debug("CPU#%d disabling modulation\n", cpu);
  76                 wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l & ~(1<<4), h);
  77         } else {
  78                 pr_debug("CPU#%d setting duty cycle to %d%%\n",
  79                         cpu, ((125 * newstate) / 10));
  80                 /* bits 63 - 5  : reserved
  81                  * bit  4       : enable/disable
  82                  * bits 3-1     : duty cycle
  83                  * bit  0       : reserved
  84                  */
  85                 l = (l & ~14);
  86                 l = l | (1<<4) | ((newstate & 0x7)<<1);
  87                 wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l, h);
  88         }
  89
  90         return 0;
  91 }
  92
  93
  94 static struct cpufreq_frequency_table p4clockmod_table[] = {
  95         {0, DC_RESV, CPUFREQ_ENTRY_INVALID},
  96         {0, DC_DFLT, 0},
  97         {0, DC_25PT, 0},
  98         {0, DC_38PT, 0},
  99         {0, DC_50PT, 0},
 100         {0, DC_64PT, 0},
 101         {0, DC_75PT, 0},
 102         {0, DC_88PT, 0},
 103         {0, DC_DISABLE, 0},
 104         {0, DC_RESV, CPUFREQ_TABLE_END},
 105 };
 106
 107
 108 static int cpufreq_p4_target(struct cpufreq_policy *policy, unsigned int index)
 109 {
 110         int i;
 111
 112         /* run on each logical CPU,
 113          * see section 13.15.3 of IA32 Intel Architecture Software
 114          * Developer's Manual, Volume 3
 115          */
 116         for_each_cpu(i, policy->cpus)
 117                 cpufreq_p4_setdc(i, p4clockmod_table[index].driver_data);
 118
 119         return 0;
 120 }
 121
 122
 123 static unsigned int cpufreq_p4_get_frequency(struct cpuinfo_x86 *c)
 124 {
 125         if (c->x86 == 0x06) {
 126                 if (cpu_has(c, X86_FEATURE_EST))
 127                         printk_once(KERN_WARNING PFX "Warning: EST-capable "
 128                                "CPU detected. The acpi-cpufreq module offers "
 129                                "voltage scaling in addition to frequency "
 130                                "scaling. You should use that instead of "
 131                                "p4-clockmod, if possible.\n");
 132                 switch (c->x86_model) {
 133                 case 0x0E: /* Core */
 134                 case 0x0F: /* Core Duo */
 135                 case 0x16: /* Celeron Core */
 136                 case 0x1C: /* Atom */
 137                         p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS;
 138                         return speedstep_get_frequency(SPEEDSTEP_CPU_PCORE);
 139                 case 0x0D: /* Pentium M (Dothan) */
 140                         p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS;
 141                         /* fall through */
 142                 case 0x09: /* Pentium M (Banias) */
 143                         return speedstep_get_frequency(SPEEDSTEP_CPU_PM);
 144                 }
 145         }
 146
 147         if (c->x86 != 0xF)
 148                 return 0;
 149
 150         /* on P-4s, the TSC runs with constant frequency independent whether
 151          * throttling is active or not. */
 152         p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS;
 153
 154         if (speedstep_detect_processor() == SPEEDSTEP_CPU_P4M) {
 155                 printk(KERN_WARNING PFX "Warning: Pentium 4-M detected. "
 156                        "The speedstep-ich or acpi cpufreq modules offer "
 157                        "voltage scaling in addition of frequency scaling. "
 158                        "You should use either one instead of p4-clockmod, "
 159                        "if possible.\n");
 160                 return speedstep_get_frequency(SPEEDSTEP_CPU_P4M);
 161         }
 162
 163         return speedstep_get_frequency(SPEEDSTEP_CPU_P4D);
 164 }
 165
 166
 167
 168 static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
 169 {
 170         struct cpuinfo_x86 *c = &cpu_data(policy->cpu);
 171         int cpuid = 0;
 172         unsigned int i;
 173
 174 #ifdef CONFIG_SMP
 175         cpumask_copy(policy->cpus, topology_sibling_cpumask(policy->cpu));
 176 #endif
 177
 178         /* Errata workaround */
 179         cpuid = (c->x86 << 8) | (c->x86_model << 4) | c->x86_mask;
 180         switch (cpuid) {
 181         case 0x0f07:
 182         case 0x0f0a:
 183         case 0x0f11:
 184         case 0x0f12:
 185                 has_N44_O17_errata[policy->cpu] = 1;
 186                 pr_debug("has errata -- disabling low frequencies\n");
 187         }
 188
 189         if (speedstep_detect_processor() == SPEEDSTEP_CPU_P4D &&
 190             c->x86_model < 2) {
 191                 /* switch to maximum frequency and measure result */
 192                 cpufreq_p4_setdc(policy->cpu, DC_DISABLE);
 193                 recalibrate_cpu_khz();
 194         }
 195         /* get max frequency */
 196         stock_freq = cpufreq_p4_get_frequency(c);
 197         if (!stock_freq)
 198                 return -EINVAL;
 199
 200         /* table init */
 201         for (i = 1; (p4clockmod_table[i].frequency != CPUFREQ_TABLE_END); i++) {
 202                 if ((i < 2) && (has_N44_O17_errata[policy->cpu]))
 203                         p4clockmod_table[i].frequency = CPUFREQ_ENTRY_INVALID;
 204                 else
 205                         p4clockmod_table[i].frequency = (stock_freq * i)/8;
 206         }
 207
 208         /* cpuinfo and default policy values */
 209
 210         /* the transition latency is set to be 1 higher than the maximum
 211          * transition latency of the ondemand governor */
 212         policy->cpuinfo.transition_latency = 10000001;
 213
 214         return cpufreq_table_validate_and_show(policy, &p4clockmod_table[0]);
 215 }
 216
 217
 218 static unsigned int cpufreq_p4_get(unsigned int cpu)
 219 {
 220         u32 l, h;
 221
 222         rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, &l, &h);
 223
 224         if (l & 0x10) {
 225                 l = l >> 1;
 226                 l &= 0x7;
 227         } else
 228                 l = DC_DISABLE;
 229
 230         if (l != DC_DISABLE)
 231                 return stock_freq * l / 8;
 232
 233         return stock_freq;
 234 }
 235
 236 static struct cpufreq_driver p4clockmod_driver = {
 237         .verify         = cpufreq_generic_frequency_table_verify,
 238         .target_index   = cpufreq_p4_target,
 239         .init           = cpufreq_p4_cpu_init,
 240         .get            = cpufreq_p4_get,
 241         .name           = "p4-clockmod",
 242         .attr           = cpufreq_generic_attr,
 243 };
 244
 245 static const struct x86_cpu_id cpufreq_p4_id[] = {
 246         { X86_VENDOR_INTEL, X86_FAMILY_ANY, X86_MODEL_ANY, X86_FEATURE_ACC },
 247         {}
 248 };
 249
 250 /*
 251  * Intentionally no MODULE_DEVICE_TABLE here: this driver should not
 252  * be auto loaded.  Please don't add one.
 253  */
 254
 255 static int __init cpufreq_p4_init(void)
 256 {
 257         int ret;
 258
 259         /*
 260          * THERM_CONTROL is architectural for IA32 now, so
 261          * we can rely on the capability checks
 262          */
 263         if (!x86_match_cpu(cpufreq_p4_id) || !boot_cpu_has(X86_FEATURE_ACPI))
 264                 return -ENODEV;
 265
 266         ret = cpufreq_register_driver(&p4clockmod_driver);
 267         if (!ret)
 268                 printk(KERN_INFO PFX "P4/Xeon(TM) CPU On-Demand Clock "
 269                                 "Modulation available\n");
 270
 271         return ret;
 272 }
 273
 274
 275 static void __exit cpufreq_p4_exit(void)
 276 {
 277         cpufreq_unregister_driver(&p4clockmod_driver);
 278 }
 279
 280
 281 MODULE_AUTHOR("Zwane Mwaikambo <zwane@commfireservices.com>");
 282 MODULE_DESCRIPTION("cpufreq driver for Pentium(TM) 4/Xeon(TM)");
 283 MODULE_LICENSE("GPL");
 284
 285 late_initcall(cpufreq_p4_init);
 286 module_exit(cpufreq_p4_exit);