drivers/cpufreq/p4-clockmod.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      Pentium 4/Xeon CPU on demand clock modulation/speed scaling
   4  *      (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
   5  *      (C) 2002 Zwane Mwaikambo <zwane@commfireservices.com>
   6  *      (C) 2002 Arjan van de Ven <arjanv@redhat.com>
   7  *      (C) 2002 Tora T. Engstad
   8  *      All Rights Reserved
   9  *
  10  *      The author(s) of this software shall not be held liable for damages
  11  *      of any nature resulting due to the use of this software. This
  12  *      software is provided AS-IS with no warranties.
  13  *
  14  *      Date            Errata                  Description
  15  *      20020525        N44, O17        12.5% or 25% DC causes lockup
  16  */
  17
  18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/smp.h>
  24 #include <linux/cpufreq.h>
  25 #include <linux/cpumask.h>
  26 #include <linux/timex.h>
  27
  28 #include <asm/processor.h>
  29 #include <asm/msr.h>
  30 #include <asm/timer.h>
  31 #include <asm/cpu_device_id.h>
  32
  33 #include "speedstep-lib.h"
  34
  35 /*
  36  * Duty Cycle (3bits), note DC_DISABLE is not specified in
  37  * intel docs i just use it to mean disable
  38  */
  39 enum {
  40         DC_RESV, DC_DFLT, DC_25PT, DC_38PT, DC_50PT,
  41         DC_64PT, DC_75PT, DC_88PT, DC_DISABLE
  42 };
  43
  44 #define DC_ENTRIES      8
  45
  46
  47 static int has_N44_O17_errata[NR_CPUS];
  48 static unsigned int stock_freq;
  49 static struct cpufreq_driver p4clockmod_driver;
  50 static unsigned int cpufreq_p4_get(unsigned int cpu);
  51
  52 static int cpufreq_p4_setdc(unsigned int cpu, unsigned int newstate)
  53 {
  54         u32 l, h;
  55
  56         if ((newstate > DC_DISABLE) || (newstate == DC_RESV))
  57                 return -EINVAL;
  58
  59         rdmsr_on_cpu(cpu, MSR_IA32_THERM_STATUS, &l, &h);
  60
  61         if (l & 0x01)
  62                 pr_debug("CPU#%d currently thermal throttled\n", cpu);
  63
  64         if (has_N44_O17_errata[cpu] &&
  65             (newstate == DC_25PT || newstate == DC_DFLT))
  66                 newstate = DC_38PT;
  67
  68         rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, &l, &h);
  69         if (newstate == DC_DISABLE) {
  70                 pr_debug("CPU#%d disabling modulation\n", cpu);
  71                 wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l & ~(1<<4), h);
  72         } else {
  73                 pr_debug("CPU#%d setting duty cycle to %d%%\n",
  74                         cpu, ((125 * newstate) / 10));
  75                 /* bits 63 - 5  : reserved
  76                  * bit  4       : enable/disable
  77                  * bits 3-1     : duty cycle
  78                  * bit  0       : reserved
  79                  */
  80                 l = (l & ~14);
  81                 l = l | (1<<4) | ((newstate & 0x7)<<1);
  82                 wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l, h);
  83         }
  84
  85         return 0;
  86 }
  87
  88
  89 static struct cpufreq_frequency_table p4clockmod_table[] = {
  90         {0, DC_RESV, CPUFREQ_ENTRY_INVALID},
  91         {0, DC_DFLT, 0},
  92         {0, DC_25PT, 0},
  93         {0, DC_38PT, 0},
  94         {0, DC_50PT, 0},
  95         {0, DC_64PT, 0},
  96         {0, DC_75PT, 0},
  97         {0, DC_88PT, 0},
  98         {0, DC_DISABLE, 0},
  99         {0, DC_RESV, CPUFREQ_TABLE_END},
 100 };
 101
 102
 103 static int cpufreq_p4_target(struct cpufreq_policy *policy, unsigned int index)
 104 {
 105         int i;
 106
 107         /* run on each logical CPU,
 108          * see section 13.15.3 of IA32 Intel Architecture Software
 109          * Developer's Manual, Volume 3
 110          */
 111         for_each_cpu(i, policy->cpus)
 112                 cpufreq_p4_setdc(i, p4clockmod_table[index].driver_data);
 113
 114         return 0;
 115 }
 116
 117
 118 static unsigned int cpufreq_p4_get_frequency(struct cpuinfo_x86 *c)
 119 {
 120         if (c->x86 == 0x06) {
 121                 if (cpu_has(c, X86_FEATURE_EST))
 122                         pr_warn_once("Warning: EST-capable CPU detected. The acpi-cpufreq module offers voltage scaling in addition to frequency scaling. You should use that instead of p4-clockmod, if possible.\n");
 123                 switch (c->x86_model) {
 124                 case 0x0E: /* Core */
 125                 case 0x0F: /* Core Duo */
 126                 case 0x16: /* Celeron Core */
 127                 case 0x1C: /* Atom */
 128                         p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS;
 129                         return speedstep_get_frequency(SPEEDSTEP_CPU_PCORE);
 130                 case 0x0D: /* Pentium M (Dothan) */
 131                         p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS;
 132                         fallthrough;
 133                 case 0x09: /* Pentium M (Banias) */
 134                         return speedstep_get_frequency(SPEEDSTEP_CPU_PM);
 135                 }
 136         }
 137
 138         if (c->x86 != 0xF)
 139                 return 0;
 140
 141         /* on P-4s, the TSC runs with constant frequency independent whether
 142          * throttling is active or not. */
 143         p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS;
 144
 145         if (speedstep_detect_processor() == SPEEDSTEP_CPU_P4M) {
 146                 pr_warn("Warning: Pentium 4-M detected. The speedstep-ich or acpi cpufreq modules offer voltage scaling in addition of frequency scaling. You should use either one instead of p4-clockmod, if possible.\n");
 147                 return speedstep_get_frequency(SPEEDSTEP_CPU_P4M);
 148         }
 149
 150         return speedstep_get_frequency(SPEEDSTEP_CPU_P4D);
 151 }
 152
 153
 154
 155 static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
 156 {
 157         struct cpuinfo_x86 *c = &cpu_data(policy->cpu);
 158         int cpuid = 0;
 159         unsigned int i;
 160
 161 #ifdef CONFIG_SMP
 162         cpumask_copy(policy->cpus, topology_sibling_cpumask(policy->cpu));
 163 #endif
 164
 165         /* Errata workaround */
 166         cpuid = (c->x86 << 8) | (c->x86_model << 4) | c->x86_stepping;
 167         switch (cpuid) {
 168         case 0x0f07:
 169         case 0x0f0a:
 170         case 0x0f11:
 171         case 0x0f12:
 172                 has_N44_O17_errata[policy->cpu] = 1;
 173                 pr_debug("has errata -- disabling low frequencies\n");
 174         }
 175
 176         if (speedstep_detect_processor() == SPEEDSTEP_CPU_P4D &&
 177             c->x86_model < 2) {
 178                 /* switch to maximum frequency and measure result */
 179                 cpufreq_p4_setdc(policy->cpu, DC_DISABLE);
 180                 recalibrate_cpu_khz();
 181         }
 182         /* get max frequency */
 183         stock_freq = cpufreq_p4_get_frequency(c);
 184         if (!stock_freq)
 185                 return -EINVAL;
 186
 187         /* table init */
 188         for (i = 1; (p4clockmod_table[i].frequency != CPUFREQ_TABLE_END); i++) {
 189                 if ((i < 2) && (has_N44_O17_errata[policy->cpu]))
 190                         p4clockmod_table[i].frequency = CPUFREQ_ENTRY_INVALID;
 191                 else
 192                         p4clockmod_table[i].frequency = (stock_freq * i)/8;
 193         }
 194
 195         /* cpuinfo and default policy values */
 196
 197         /* the transition latency is set to be 1 higher than the maximum
 198          * transition latency of the ondemand governor */
 199         policy->cpuinfo.transition_latency = 10000001;
 200         policy->freq_table = &p4clockmod_table[0];
 201
 202         return 0;
 203 }
 204
 205
 206 static unsigned int cpufreq_p4_get(unsigned int cpu)
 207 {
 208         u32 l, h;
 209
 210         rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, &l, &h);
 211
 212         if (l & 0x10) {
 213                 l = l >> 1;
 214                 l &= 0x7;
 215         } else
 216                 l = DC_DISABLE;
 217
 218         if (l != DC_DISABLE)
 219                 return stock_freq * l / 8;
 220
 221         return stock_freq;
 222 }
 223
 224 static struct cpufreq_driver p4clockmod_driver = {
 225         .verify         = cpufreq_generic_frequency_table_verify,
 226         .target_index   = cpufreq_p4_target,
 227         .init           = cpufreq_p4_cpu_init,
 228         .get            = cpufreq_p4_get,
 229         .name           = "p4-clockmod",
 230         .attr           = cpufreq_generic_attr,
 231 };
 232
 233 static const struct x86_cpu_id cpufreq_p4_id[] = {
 234         X86_MATCH_VENDOR_FEATURE(INTEL, X86_FEATURE_ACC, NULL),
 235         {}
 236 };
 237
 238 /*
 239  * Intentionally no MODULE_DEVICE_TABLE here: this driver should not
 240  * be auto loaded.  Please don't add one.
 241  */
 242
 243 static int __init cpufreq_p4_init(void)
 244 {
 245         int ret;
 246
 247         /*
 248          * THERM_CONTROL is architectural for IA32 now, so
 249          * we can rely on the capability checks
 250          */
 251         if (!x86_match_cpu(cpufreq_p4_id) || !boot_cpu_has(X86_FEATURE_ACPI))
 252                 return -ENODEV;
 253
 254         ret = cpufreq_register_driver(&p4clockmod_driver);
 255         if (!ret)
 256                 pr_info("P4/Xeon(TM) CPU On-Demand Clock Modulation available\n");
 257
 258         return ret;
 259 }
 260
 261
 262 static void __exit cpufreq_p4_exit(void)
 263 {
 264         cpufreq_unregister_driver(&p4clockmod_driver);
 265 }
 266
 267
 268 MODULE_AUTHOR("Zwane Mwaikambo <zwane@commfireservices.com>");
 269 MODULE_DESCRIPTION("cpufreq driver for Pentium(TM) 4/Xeon(TM)");
 270 MODULE_LICENSE("GPL");
 271
 272 late_initcall(cpufreq_p4_init);
 273 module_exit(cpufreq_p4_exit);