274 lines
6.9 KiB
C
274 lines
6.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Pentium 4/Xeon CPU on demand clock modulation/speed scaling
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* (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
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* (C) 2002 Zwane Mwaikambo <zwane@commfireservices.com>
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* (C) 2002 Arjan van de Ven <arjanv@redhat.com>
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* (C) 2002 Tora T. Engstad
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* All Rights Reserved
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*
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* The author(s) of this software shall not be held liable for damages
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* of any nature resulting due to the use of this software. This
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* software is provided AS-IS with no warranties.
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*
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* Date Errata Description
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* 20020525 N44, O17 12.5% or 25% DC causes lockup
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/cpufreq.h>
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#include <linux/cpumask.h>
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#include <linux/timex.h>
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#include <asm/processor.h>
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#include <asm/msr.h>
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#include <asm/timer.h>
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#include <asm/cpu_device_id.h>
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#include "speedstep-lib.h"
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/*
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* Duty Cycle (3bits), note DC_DISABLE is not specified in
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* intel docs i just use it to mean disable
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*/
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enum {
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DC_RESV, DC_DFLT, DC_25PT, DC_38PT, DC_50PT,
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DC_64PT, DC_75PT, DC_88PT, DC_DISABLE
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};
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#define DC_ENTRIES 8
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static int has_N44_O17_errata[NR_CPUS];
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static unsigned int stock_freq;
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static struct cpufreq_driver p4clockmod_driver;
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static unsigned int cpufreq_p4_get(unsigned int cpu);
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static int cpufreq_p4_setdc(unsigned int cpu, unsigned int newstate)
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{
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u32 l, h;
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if ((newstate > DC_DISABLE) || (newstate == DC_RESV))
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return -EINVAL;
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rdmsr_on_cpu(cpu, MSR_IA32_THERM_STATUS, &l, &h);
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if (l & 0x01)
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pr_debug("CPU#%d currently thermal throttled\n", cpu);
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if (has_N44_O17_errata[cpu] &&
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(newstate == DC_25PT || newstate == DC_DFLT))
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newstate = DC_38PT;
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rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, &l, &h);
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if (newstate == DC_DISABLE) {
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pr_debug("CPU#%d disabling modulation\n", cpu);
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wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l & ~(1<<4), h);
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} else {
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pr_debug("CPU#%d setting duty cycle to %d%%\n",
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cpu, ((125 * newstate) / 10));
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/* bits 63 - 5 : reserved
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* bit 4 : enable/disable
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* bits 3-1 : duty cycle
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* bit 0 : reserved
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*/
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l = (l & ~14);
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l = l | (1<<4) | ((newstate & 0x7)<<1);
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wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l, h);
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}
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return 0;
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}
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static struct cpufreq_frequency_table p4clockmod_table[] = {
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{0, DC_RESV, CPUFREQ_ENTRY_INVALID},
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{0, DC_DFLT, 0},
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{0, DC_25PT, 0},
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{0, DC_38PT, 0},
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{0, DC_50PT, 0},
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{0, DC_64PT, 0},
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{0, DC_75PT, 0},
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{0, DC_88PT, 0},
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{0, DC_DISABLE, 0},
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{0, DC_RESV, CPUFREQ_TABLE_END},
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};
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static int cpufreq_p4_target(struct cpufreq_policy *policy, unsigned int index)
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{
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int i;
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/* run on each logical CPU,
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* see section 13.15.3 of IA32 Intel Architecture Software
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* Developer's Manual, Volume 3
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*/
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for_each_cpu(i, policy->cpus)
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cpufreq_p4_setdc(i, p4clockmod_table[index].driver_data);
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return 0;
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}
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static unsigned int cpufreq_p4_get_frequency(struct cpuinfo_x86 *c)
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{
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if (c->x86 == 0x06) {
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if (cpu_has(c, X86_FEATURE_EST))
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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");
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switch (c->x86_model) {
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case 0x0E: /* Core */
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case 0x0F: /* Core Duo */
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case 0x16: /* Celeron Core */
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case 0x1C: /* Atom */
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p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS;
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return speedstep_get_frequency(SPEEDSTEP_CPU_PCORE);
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case 0x0D: /* Pentium M (Dothan) */
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p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS;
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/* fall through */
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case 0x09: /* Pentium M (Banias) */
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return speedstep_get_frequency(SPEEDSTEP_CPU_PM);
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}
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}
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if (c->x86 != 0xF)
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return 0;
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/* on P-4s, the TSC runs with constant frequency independent whether
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* throttling is active or not. */
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p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS;
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if (speedstep_detect_processor() == SPEEDSTEP_CPU_P4M) {
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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");
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return speedstep_get_frequency(SPEEDSTEP_CPU_P4M);
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}
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return speedstep_get_frequency(SPEEDSTEP_CPU_P4D);
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}
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static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
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{
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struct cpuinfo_x86 *c = &cpu_data(policy->cpu);
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int cpuid = 0;
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unsigned int i;
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#ifdef CONFIG_SMP
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cpumask_copy(policy->cpus, topology_sibling_cpumask(policy->cpu));
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#endif
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/* Errata workaround */
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cpuid = (c->x86 << 8) | (c->x86_model << 4) | c->x86_stepping;
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switch (cpuid) {
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case 0x0f07:
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case 0x0f0a:
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case 0x0f11:
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case 0x0f12:
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has_N44_O17_errata[policy->cpu] = 1;
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pr_debug("has errata -- disabling low frequencies\n");
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}
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if (speedstep_detect_processor() == SPEEDSTEP_CPU_P4D &&
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c->x86_model < 2) {
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/* switch to maximum frequency and measure result */
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cpufreq_p4_setdc(policy->cpu, DC_DISABLE);
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recalibrate_cpu_khz();
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}
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/* get max frequency */
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stock_freq = cpufreq_p4_get_frequency(c);
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if (!stock_freq)
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return -EINVAL;
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/* table init */
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for (i = 1; (p4clockmod_table[i].frequency != CPUFREQ_TABLE_END); i++) {
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if ((i < 2) && (has_N44_O17_errata[policy->cpu]))
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p4clockmod_table[i].frequency = CPUFREQ_ENTRY_INVALID;
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else
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p4clockmod_table[i].frequency = (stock_freq * i)/8;
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}
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/* cpuinfo and default policy values */
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/* the transition latency is set to be 1 higher than the maximum
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* transition latency of the ondemand governor */
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policy->cpuinfo.transition_latency = 10000001;
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policy->freq_table = &p4clockmod_table[0];
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return 0;
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}
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static unsigned int cpufreq_p4_get(unsigned int cpu)
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{
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u32 l, h;
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rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, &l, &h);
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if (l & 0x10) {
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l = l >> 1;
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l &= 0x7;
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} else
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l = DC_DISABLE;
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if (l != DC_DISABLE)
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return stock_freq * l / 8;
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return stock_freq;
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}
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static struct cpufreq_driver p4clockmod_driver = {
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.verify = cpufreq_generic_frequency_table_verify,
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.target_index = cpufreq_p4_target,
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.init = cpufreq_p4_cpu_init,
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.get = cpufreq_p4_get,
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.name = "p4-clockmod",
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.attr = cpufreq_generic_attr,
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};
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static const struct x86_cpu_id cpufreq_p4_id[] = {
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X86_MATCH_VENDOR_FEATURE(INTEL, X86_FEATURE_ACC, NULL),
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{}
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};
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/*
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* Intentionally no MODULE_DEVICE_TABLE here: this driver should not
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* be auto loaded. Please don't add one.
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*/
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static int __init cpufreq_p4_init(void)
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{
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int ret;
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/*
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* THERM_CONTROL is architectural for IA32 now, so
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* we can rely on the capability checks
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*/
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if (!x86_match_cpu(cpufreq_p4_id) || !boot_cpu_has(X86_FEATURE_ACPI))
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return -ENODEV;
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ret = cpufreq_register_driver(&p4clockmod_driver);
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if (!ret)
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pr_info("P4/Xeon(TM) CPU On-Demand Clock Modulation available\n");
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return ret;
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}
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static void __exit cpufreq_p4_exit(void)
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{
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cpufreq_unregister_driver(&p4clockmod_driver);
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}
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MODULE_AUTHOR("Zwane Mwaikambo <zwane@commfireservices.com>");
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MODULE_DESCRIPTION("cpufreq driver for Pentium(TM) 4/Xeon(TM)");
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MODULE_LICENSE("GPL");
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late_initcall(cpufreq_p4_init);
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module_exit(cpufreq_p4_exit);
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