diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/cpufreq/p4-clockmod.c | 273 |
1 files changed, 273 insertions, 0 deletions
diff --git a/drivers/cpufreq/p4-clockmod.c b/drivers/cpufreq/p4-clockmod.c new file mode 100644 index 000000000..ef0a3216a --- /dev/null +++ b/drivers/cpufreq/p4-clockmod.c @@ -0,0 +1,273 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Pentium 4/Xeon CPU on demand clock modulation/speed scaling + * (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de> + * (C) 2002 Zwane Mwaikambo <zwane@commfireservices.com> + * (C) 2002 Arjan van de Ven <arjanv@redhat.com> + * (C) 2002 Tora T. Engstad + * All Rights Reserved + * + * The author(s) of this software shall not be held liable for damages + * of any nature resulting due to the use of this software. This + * software is provided AS-IS with no warranties. + * + * Date Errata Description + * 20020525 N44, O17 12.5% or 25% DC causes lockup + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/smp.h> +#include <linux/cpufreq.h> +#include <linux/cpumask.h> +#include <linux/timex.h> + +#include <asm/processor.h> +#include <asm/msr.h> +#include <asm/timer.h> +#include <asm/cpu_device_id.h> + +#include "speedstep-lib.h" + +/* + * Duty Cycle (3bits), note DC_DISABLE is not specified in + * intel docs i just use it to mean disable + */ +enum { + DC_RESV, DC_DFLT, DC_25PT, DC_38PT, DC_50PT, + DC_64PT, DC_75PT, DC_88PT, DC_DISABLE +}; + +#define DC_ENTRIES 8 + + +static int has_N44_O17_errata[NR_CPUS]; +static unsigned int stock_freq; +static struct cpufreq_driver p4clockmod_driver; +static unsigned int cpufreq_p4_get(unsigned int cpu); + +static int cpufreq_p4_setdc(unsigned int cpu, unsigned int newstate) +{ + u32 l, h; + + if ((newstate > DC_DISABLE) || (newstate == DC_RESV)) + return -EINVAL; + + rdmsr_on_cpu(cpu, MSR_IA32_THERM_STATUS, &l, &h); + + if (l & 0x01) + pr_debug("CPU#%d currently thermal throttled\n", cpu); + + if (has_N44_O17_errata[cpu] && + (newstate == DC_25PT || newstate == DC_DFLT)) + newstate = DC_38PT; + + rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, &l, &h); + if (newstate == DC_DISABLE) { + pr_debug("CPU#%d disabling modulation\n", cpu); + wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l & ~(1<<4), h); + } else { + pr_debug("CPU#%d setting duty cycle to %d%%\n", + cpu, ((125 * newstate) / 10)); + /* bits 63 - 5 : reserved + * bit 4 : enable/disable + * bits 3-1 : duty cycle + * bit 0 : reserved + */ + l = (l & ~14); + l = l | (1<<4) | ((newstate & 0x7)<<1); + wrmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, l, h); + } + + return 0; +} + + +static struct cpufreq_frequency_table p4clockmod_table[] = { + {0, DC_RESV, CPUFREQ_ENTRY_INVALID}, + {0, DC_DFLT, 0}, + {0, DC_25PT, 0}, + {0, DC_38PT, 0}, + {0, DC_50PT, 0}, + {0, DC_64PT, 0}, + {0, DC_75PT, 0}, + {0, DC_88PT, 0}, + {0, DC_DISABLE, 0}, + {0, DC_RESV, CPUFREQ_TABLE_END}, +}; + + +static int cpufreq_p4_target(struct cpufreq_policy *policy, unsigned int index) +{ + int i; + + /* run on each logical CPU, + * see section 13.15.3 of IA32 Intel Architecture Software + * Developer's Manual, Volume 3 + */ + for_each_cpu(i, policy->cpus) + cpufreq_p4_setdc(i, p4clockmod_table[index].driver_data); + + return 0; +} + + +static unsigned int cpufreq_p4_get_frequency(struct cpuinfo_x86 *c) +{ + if (c->x86 == 0x06) { + if (cpu_has(c, X86_FEATURE_EST)) + 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"); + switch (c->x86_model) { + case 0x0E: /* Core */ + case 0x0F: /* Core Duo */ + case 0x16: /* Celeron Core */ + case 0x1C: /* Atom */ + p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS; + return speedstep_get_frequency(SPEEDSTEP_CPU_PCORE); + case 0x0D: /* Pentium M (Dothan) */ + p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS; + fallthrough; + case 0x09: /* Pentium M (Banias) */ + return speedstep_get_frequency(SPEEDSTEP_CPU_PM); + } + } + + if (c->x86 != 0xF) + return 0; + + /* on P-4s, the TSC runs with constant frequency independent whether + * throttling is active or not. */ + p4clockmod_driver.flags |= CPUFREQ_CONST_LOOPS; + + if (speedstep_detect_processor() == SPEEDSTEP_CPU_P4M) { + 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"); + return speedstep_get_frequency(SPEEDSTEP_CPU_P4M); + } + + return speedstep_get_frequency(SPEEDSTEP_CPU_P4D); +} + + + +static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy) +{ + struct cpuinfo_x86 *c = &cpu_data(policy->cpu); + int cpuid = 0; + unsigned int i; + +#ifdef CONFIG_SMP + cpumask_copy(policy->cpus, topology_sibling_cpumask(policy->cpu)); +#endif + + /* Errata workaround */ + cpuid = (c->x86 << 8) | (c->x86_model << 4) | c->x86_stepping; + switch (cpuid) { + case 0x0f07: + case 0x0f0a: + case 0x0f11: + case 0x0f12: + has_N44_O17_errata[policy->cpu] = 1; + pr_debug("has errata -- disabling low frequencies\n"); + } + + if (speedstep_detect_processor() == SPEEDSTEP_CPU_P4D && + c->x86_model < 2) { + /* switch to maximum frequency and measure result */ + cpufreq_p4_setdc(policy->cpu, DC_DISABLE); + recalibrate_cpu_khz(); + } + /* get max frequency */ + stock_freq = cpufreq_p4_get_frequency(c); + if (!stock_freq) + return -EINVAL; + + /* table init */ + for (i = 1; (p4clockmod_table[i].frequency != CPUFREQ_TABLE_END); i++) { + if ((i < 2) && (has_N44_O17_errata[policy->cpu])) + p4clockmod_table[i].frequency = CPUFREQ_ENTRY_INVALID; + else + p4clockmod_table[i].frequency = (stock_freq * i)/8; + } + + /* cpuinfo and default policy values */ + + /* the transition latency is set to be 1 higher than the maximum + * transition latency of the ondemand governor */ + policy->cpuinfo.transition_latency = 10000001; + policy->freq_table = &p4clockmod_table[0]; + + return 0; +} + + +static unsigned int cpufreq_p4_get(unsigned int cpu) +{ + u32 l, h; + + rdmsr_on_cpu(cpu, MSR_IA32_THERM_CONTROL, &l, &h); + + if (l & 0x10) { + l = l >> 1; + l &= 0x7; + } else + l = DC_DISABLE; + + if (l != DC_DISABLE) + return stock_freq * l / 8; + + return stock_freq; +} + +static struct cpufreq_driver p4clockmod_driver = { + .verify = cpufreq_generic_frequency_table_verify, + .target_index = cpufreq_p4_target, + .init = cpufreq_p4_cpu_init, + .get = cpufreq_p4_get, + .name = "p4-clockmod", + .attr = cpufreq_generic_attr, +}; + +static const struct x86_cpu_id cpufreq_p4_id[] = { + X86_MATCH_VENDOR_FEATURE(INTEL, X86_FEATURE_ACC, NULL), + {} +}; + +/* + * Intentionally no MODULE_DEVICE_TABLE here: this driver should not + * be auto loaded. Please don't add one. + */ + +static int __init cpufreq_p4_init(void) +{ + int ret; + + /* + * THERM_CONTROL is architectural for IA32 now, so + * we can rely on the capability checks + */ + if (!x86_match_cpu(cpufreq_p4_id) || !boot_cpu_has(X86_FEATURE_ACPI)) + return -ENODEV; + + ret = cpufreq_register_driver(&p4clockmod_driver); + if (!ret) + pr_info("P4/Xeon(TM) CPU On-Demand Clock Modulation available\n"); + + return ret; +} + + +static void __exit cpufreq_p4_exit(void) +{ + cpufreq_unregister_driver(&p4clockmod_driver); +} + + +MODULE_AUTHOR("Zwane Mwaikambo <zwane@commfireservices.com>"); +MODULE_DESCRIPTION("cpufreq driver for Pentium(TM) 4/Xeon(TM)"); +MODULE_LICENSE("GPL"); + +late_initcall(cpufreq_p4_init); +module_exit(cpufreq_p4_exit); |