diff options
Diffstat (limited to 'drivers/cpufreq/speedstep-lib.c')
| -rw-r--r-- | drivers/cpufreq/speedstep-lib.c | 479 |
1 files changed, 479 insertions, 0 deletions
diff --git a/drivers/cpufreq/speedstep-lib.c b/drivers/cpufreq/speedstep-lib.c new file mode 100644 index 000000000..0b66df4ed --- /dev/null +++ b/drivers/cpufreq/speedstep-lib.c @@ -0,0 +1,479 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de> + * + * Library for common functions for Intel SpeedStep v.1 and v.2 support + * + * BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous* + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/init.h> +#include <linux/cpufreq.h> + +#include <asm/msr.h> +#include <asm/tsc.h> +#include "speedstep-lib.h" + +#define PFX "speedstep-lib: " + +#ifdef CONFIG_X86_SPEEDSTEP_RELAXED_CAP_CHECK +static int relaxed_check; +#else +#define relaxed_check 0 +#endif + +/********************************************************************* + * GET PROCESSOR CORE SPEED IN KHZ * + *********************************************************************/ + +static unsigned int pentium3_get_frequency(enum speedstep_processor processor) +{ + /* See table 14 of p3_ds.pdf and table 22 of 29834003.pdf */ + static const struct { + unsigned int ratio; /* Frequency Multiplier (x10) */ + u8 bitmap; /* power on configuration bits + [27, 25:22] (in MSR 0x2a) */ + } msr_decode_mult[] = { + { 30, 0x01 }, + { 35, 0x05 }, + { 40, 0x02 }, + { 45, 0x06 }, + { 50, 0x00 }, + { 55, 0x04 }, + { 60, 0x0b }, + { 65, 0x0f }, + { 70, 0x09 }, + { 75, 0x0d }, + { 80, 0x0a }, + { 85, 0x26 }, + { 90, 0x20 }, + { 100, 0x2b }, + { 0, 0xff } /* error or unknown value */ + }; + + /* PIII(-M) FSB settings: see table b1-b of 24547206.pdf */ + static const struct { + unsigned int value; /* Front Side Bus speed in MHz */ + u8 bitmap; /* power on configuration bits [18: 19] + (in MSR 0x2a) */ + } msr_decode_fsb[] = { + { 66, 0x0 }, + { 100, 0x2 }, + { 133, 0x1 }, + { 0, 0xff} + }; + + u32 msr_lo, msr_tmp; + int i = 0, j = 0; + + /* read MSR 0x2a - we only need the low 32 bits */ + rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp); + pr_debug("P3 - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n", msr_lo, msr_tmp); + msr_tmp = msr_lo; + + /* decode the FSB */ + msr_tmp &= 0x00c0000; + msr_tmp >>= 18; + while (msr_tmp != msr_decode_fsb[i].bitmap) { + if (msr_decode_fsb[i].bitmap == 0xff) + return 0; + i++; + } + + /* decode the multiplier */ + if (processor == SPEEDSTEP_CPU_PIII_C_EARLY) { + pr_debug("workaround for early PIIIs\n"); + msr_lo &= 0x03c00000; + } else + msr_lo &= 0x0bc00000; + msr_lo >>= 22; + while (msr_lo != msr_decode_mult[j].bitmap) { + if (msr_decode_mult[j].bitmap == 0xff) + return 0; + j++; + } + + pr_debug("speed is %u\n", + (msr_decode_mult[j].ratio * msr_decode_fsb[i].value * 100)); + + return msr_decode_mult[j].ratio * msr_decode_fsb[i].value * 100; +} + + +static unsigned int pentiumM_get_frequency(void) +{ + u32 msr_lo, msr_tmp; + + rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp); + pr_debug("PM - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n", msr_lo, msr_tmp); + + /* see table B-2 of 24547212.pdf */ + if (msr_lo & 0x00040000) { + printk(KERN_DEBUG PFX "PM - invalid FSB: 0x%x 0x%x\n", + msr_lo, msr_tmp); + return 0; + } + + msr_tmp = (msr_lo >> 22) & 0x1f; + pr_debug("bits 22-26 are 0x%x, speed is %u\n", + msr_tmp, (msr_tmp * 100 * 1000)); + + return msr_tmp * 100 * 1000; +} + +static unsigned int pentium_core_get_frequency(void) +{ + u32 fsb = 0; + u32 msr_lo, msr_tmp; + int ret; + + rdmsr(MSR_FSB_FREQ, msr_lo, msr_tmp); + /* see table B-2 of 25366920.pdf */ + switch (msr_lo & 0x07) { + case 5: + fsb = 100000; + break; + case 1: + fsb = 133333; + break; + case 3: + fsb = 166667; + break; + case 2: + fsb = 200000; + break; + case 0: + fsb = 266667; + break; + case 4: + fsb = 333333; + break; + default: + pr_err("PCORE - MSR_FSB_FREQ undefined value\n"); + } + + rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp); + pr_debug("PCORE - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n", + msr_lo, msr_tmp); + + msr_tmp = (msr_lo >> 22) & 0x1f; + pr_debug("bits 22-26 are 0x%x, speed is %u\n", + msr_tmp, (msr_tmp * fsb)); + + ret = (msr_tmp * fsb); + return ret; +} + + +static unsigned int pentium4_get_frequency(void) +{ + struct cpuinfo_x86 *c = &boot_cpu_data; + u32 msr_lo, msr_hi, mult; + unsigned int fsb = 0; + unsigned int ret; + u8 fsb_code; + + /* Pentium 4 Model 0 and 1 do not have the Core Clock Frequency + * to System Bus Frequency Ratio Field in the Processor Frequency + * Configuration Register of the MSR. Therefore the current + * frequency cannot be calculated and has to be measured. + */ + if (c->x86_model < 2) + return cpu_khz; + + rdmsr(0x2c, msr_lo, msr_hi); + + pr_debug("P4 - MSR_EBC_FREQUENCY_ID: 0x%x 0x%x\n", msr_lo, msr_hi); + + /* decode the FSB: see IA-32 Intel (C) Architecture Software + * Developer's Manual, Volume 3: System Prgramming Guide, + * revision #12 in Table B-1: MSRs in the Pentium 4 and + * Intel Xeon Processors, on page B-4 and B-5. + */ + fsb_code = (msr_lo >> 16) & 0x7; + switch (fsb_code) { + case 0: + fsb = 100 * 1000; + break; + case 1: + fsb = 13333 * 10; + break; + case 2: + fsb = 200 * 1000; + break; + } + + if (!fsb) + printk(KERN_DEBUG PFX "couldn't detect FSB speed. " + "Please send an e-mail to <linux@brodo.de>\n"); + + /* Multiplier. */ + mult = msr_lo >> 24; + + pr_debug("P4 - FSB %u kHz; Multiplier %u; Speed %u kHz\n", + fsb, mult, (fsb * mult)); + + ret = (fsb * mult); + return ret; +} + + +/* Warning: may get called from smp_call_function_single. */ +unsigned int speedstep_get_frequency(enum speedstep_processor processor) +{ + switch (processor) { + case SPEEDSTEP_CPU_PCORE: + return pentium_core_get_frequency(); + case SPEEDSTEP_CPU_PM: + return pentiumM_get_frequency(); + case SPEEDSTEP_CPU_P4D: + case SPEEDSTEP_CPU_P4M: + return pentium4_get_frequency(); + case SPEEDSTEP_CPU_PIII_T: + case SPEEDSTEP_CPU_PIII_C: + case SPEEDSTEP_CPU_PIII_C_EARLY: + return pentium3_get_frequency(processor); + default: + return 0; + } + return 0; +} +EXPORT_SYMBOL_GPL(speedstep_get_frequency); + + +/********************************************************************* + * DETECT SPEEDSTEP-CAPABLE PROCESSOR * + *********************************************************************/ + +/* Keep in sync with the x86_cpu_id tables in the different modules */ +enum speedstep_processor speedstep_detect_processor(void) +{ + struct cpuinfo_x86 *c = &cpu_data(0); + u32 ebx, msr_lo, msr_hi; + + pr_debug("x86: %x, model: %x\n", c->x86, c->x86_model); + + if ((c->x86_vendor != X86_VENDOR_INTEL) || + ((c->x86 != 6) && (c->x86 != 0xF))) + return 0; + + if (c->x86 == 0xF) { + /* Intel Mobile Pentium 4-M + * or Intel Mobile Pentium 4 with 533 MHz FSB */ + if (c->x86_model != 2) + return 0; + + ebx = cpuid_ebx(0x00000001); + ebx &= 0x000000FF; + + pr_debug("ebx value is %x, x86_stepping is %x\n", ebx, c->x86_stepping); + + switch (c->x86_stepping) { + case 4: + /* + * B-stepping [M-P4-M] + * sample has ebx = 0x0f, production has 0x0e. + */ + if ((ebx == 0x0e) || (ebx == 0x0f)) + return SPEEDSTEP_CPU_P4M; + break; + case 7: + /* + * C-stepping [M-P4-M] + * needs to have ebx=0x0e, else it's a celeron: + * cf. 25130917.pdf / page 7, footnote 5 even + * though 25072120.pdf / page 7 doesn't say + * samples are only of B-stepping... + */ + if (ebx == 0x0e) + return SPEEDSTEP_CPU_P4M; + break; + case 9: + /* + * D-stepping [M-P4-M or M-P4/533] + * + * this is totally strange: CPUID 0x0F29 is + * used by M-P4-M, M-P4/533 and(!) Celeron CPUs. + * The latter need to be sorted out as they don't + * support speedstep. + * Celerons with CPUID 0x0F29 may have either + * ebx=0x8 or 0xf -- 25130917.pdf doesn't say anything + * specific. + * M-P4-Ms may have either ebx=0xe or 0xf [see above] + * M-P4/533 have either ebx=0xe or 0xf. [25317607.pdf] + * also, M-P4M HTs have ebx=0x8, too + * For now, they are distinguished by the model_id + * string + */ + if ((ebx == 0x0e) || + (strstr(c->x86_model_id, + "Mobile Intel(R) Pentium(R) 4") != NULL)) + return SPEEDSTEP_CPU_P4M; + break; + default: + break; + } + return 0; + } + + switch (c->x86_model) { + case 0x0B: /* Intel PIII [Tualatin] */ + /* cpuid_ebx(1) is 0x04 for desktop PIII, + * 0x06 for mobile PIII-M */ + ebx = cpuid_ebx(0x00000001); + pr_debug("ebx is %x\n", ebx); + + ebx &= 0x000000FF; + + if (ebx != 0x06) + return 0; + + /* So far all PIII-M processors support SpeedStep. See + * Intel's 24540640.pdf of June 2003 + */ + return SPEEDSTEP_CPU_PIII_T; + + case 0x08: /* Intel PIII [Coppermine] */ + + /* all mobile PIII Coppermines have FSB 100 MHz + * ==> sort out a few desktop PIIIs. */ + rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_hi); + pr_debug("Coppermine: MSR_IA32_EBL_CR_POWERON is 0x%x, 0x%x\n", + msr_lo, msr_hi); + msr_lo &= 0x00c0000; + if (msr_lo != 0x0080000) + return 0; + + /* + * If the processor is a mobile version, + * platform ID has bit 50 set + * it has SpeedStep technology if either + * bit 56 or 57 is set + */ + rdmsr(MSR_IA32_PLATFORM_ID, msr_lo, msr_hi); + pr_debug("Coppermine: MSR_IA32_PLATFORM ID is 0x%x, 0x%x\n", + msr_lo, msr_hi); + if ((msr_hi & (1<<18)) && + (relaxed_check ? 1 : (msr_hi & (3<<24)))) { + if (c->x86_stepping == 0x01) { + pr_debug("early PIII version\n"); + return SPEEDSTEP_CPU_PIII_C_EARLY; + } else + return SPEEDSTEP_CPU_PIII_C; + } + fallthrough; + default: + return 0; + } +} +EXPORT_SYMBOL_GPL(speedstep_detect_processor); + + +/********************************************************************* + * DETECT SPEEDSTEP SPEEDS * + *********************************************************************/ + +unsigned int speedstep_get_freqs(enum speedstep_processor processor, + unsigned int *low_speed, + unsigned int *high_speed, + unsigned int *transition_latency, + void (*set_state) (unsigned int state)) +{ + unsigned int prev_speed; + unsigned int ret = 0; + unsigned long flags; + ktime_t tv1, tv2; + + if ((!processor) || (!low_speed) || (!high_speed) || (!set_state)) + return -EINVAL; + + pr_debug("trying to determine both speeds\n"); + + /* get current speed */ + prev_speed = speedstep_get_frequency(processor); + if (!prev_speed) + return -EIO; + + pr_debug("previous speed is %u\n", prev_speed); + + preempt_disable(); + local_irq_save(flags); + + /* switch to low state */ + set_state(SPEEDSTEP_LOW); + *low_speed = speedstep_get_frequency(processor); + if (!*low_speed) { + ret = -EIO; + goto out; + } + + pr_debug("low speed is %u\n", *low_speed); + + /* start latency measurement */ + if (transition_latency) + tv1 = ktime_get(); + + /* switch to high state */ + set_state(SPEEDSTEP_HIGH); + + /* end latency measurement */ + if (transition_latency) + tv2 = ktime_get(); + + *high_speed = speedstep_get_frequency(processor); + if (!*high_speed) { + ret = -EIO; + goto out; + } + + pr_debug("high speed is %u\n", *high_speed); + + if (*low_speed == *high_speed) { + ret = -ENODEV; + goto out; + } + + /* switch to previous state, if necessary */ + if (*high_speed != prev_speed) + set_state(SPEEDSTEP_LOW); + + if (transition_latency) { + *transition_latency = ktime_to_us(ktime_sub(tv2, tv1)); + pr_debug("transition latency is %u uSec\n", *transition_latency); + + /* convert uSec to nSec and add 20% for safety reasons */ + *transition_latency *= 1200; + + /* check if the latency measurement is too high or too low + * and set it to a safe value (500uSec) in that case + */ + if (*transition_latency > 10000000 || + *transition_latency < 50000) { + pr_warn("frequency transition measured seems out of range (%u nSec), falling back to a safe one of %u nSec\n", + *transition_latency, 500000); + *transition_latency = 500000; + } + } + +out: + local_irq_restore(flags); + preempt_enable(); + + return ret; +} +EXPORT_SYMBOL_GPL(speedstep_get_freqs); + +#ifdef CONFIG_X86_SPEEDSTEP_RELAXED_CAP_CHECK +module_param(relaxed_check, int, 0444); +MODULE_PARM_DESC(relaxed_check, + "Don't do all checks for speedstep capability."); +#endif + +MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>"); +MODULE_DESCRIPTION("Library for Intel SpeedStep 1 or 2 cpufreq drivers."); +MODULE_LICENSE("GPL"); |