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325 lines
8.3 KiB
C
325 lines
8.3 KiB
C
/*
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* (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
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*
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* Licensed under the terms of the GNU GPL License version 2.
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*
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* BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
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*/
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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/cpufreq.h>
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#include <linux/timex.h>
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#include <asm/msr.h>
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#include <asm/processor.h>
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static struct cpufreq_driver longrun_driver;
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/**
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* longrun_{low,high}_freq is needed for the conversion of cpufreq kHz
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* values into per cent values. In TMTA microcode, the following is valid:
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* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
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*/
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static unsigned int longrun_low_freq, longrun_high_freq;
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/**
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* longrun_get_policy - get the current LongRun policy
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* @policy: struct cpufreq_policy where current policy is written into
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*
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* Reads the current LongRun policy by access to MSR_TMTA_LONGRUN_FLAGS
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* and MSR_TMTA_LONGRUN_CTRL
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*/
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static void __cpuinit longrun_get_policy(struct cpufreq_policy *policy)
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{
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u32 msr_lo, msr_hi;
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rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
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pr_debug("longrun flags are %x - %x\n", msr_lo, msr_hi);
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if (msr_lo & 0x01)
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policy->policy = CPUFREQ_POLICY_PERFORMANCE;
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else
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policy->policy = CPUFREQ_POLICY_POWERSAVE;
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rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
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pr_debug("longrun ctrl is %x - %x\n", msr_lo, msr_hi);
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msr_lo &= 0x0000007F;
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msr_hi &= 0x0000007F;
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if (longrun_high_freq <= longrun_low_freq) {
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/* Assume degenerate Longrun table */
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policy->min = policy->max = longrun_high_freq;
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} else {
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policy->min = longrun_low_freq + msr_lo *
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((longrun_high_freq - longrun_low_freq) / 100);
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policy->max = longrun_low_freq + msr_hi *
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((longrun_high_freq - longrun_low_freq) / 100);
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}
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policy->cpu = 0;
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}
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/**
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* longrun_set_policy - sets a new CPUFreq policy
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* @policy: new policy
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*
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* Sets a new CPUFreq policy on LongRun-capable processors. This function
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* has to be called with cpufreq_driver locked.
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*/
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static int longrun_set_policy(struct cpufreq_policy *policy)
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{
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u32 msr_lo, msr_hi;
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u32 pctg_lo, pctg_hi;
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if (!policy)
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return -EINVAL;
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if (longrun_high_freq <= longrun_low_freq) {
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/* Assume degenerate Longrun table */
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pctg_lo = pctg_hi = 100;
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} else {
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pctg_lo = (policy->min - longrun_low_freq) /
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((longrun_high_freq - longrun_low_freq) / 100);
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pctg_hi = (policy->max - longrun_low_freq) /
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((longrun_high_freq - longrun_low_freq) / 100);
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}
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if (pctg_hi > 100)
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pctg_hi = 100;
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if (pctg_lo > pctg_hi)
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pctg_lo = pctg_hi;
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/* performance or economy mode */
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rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
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msr_lo &= 0xFFFFFFFE;
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switch (policy->policy) {
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case CPUFREQ_POLICY_PERFORMANCE:
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msr_lo |= 0x00000001;
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break;
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case CPUFREQ_POLICY_POWERSAVE:
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break;
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}
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wrmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
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/* lower and upper boundary */
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rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
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msr_lo &= 0xFFFFFF80;
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msr_hi &= 0xFFFFFF80;
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msr_lo |= pctg_lo;
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msr_hi |= pctg_hi;
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wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
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return 0;
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}
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/**
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* longrun_verify_poliy - verifies a new CPUFreq policy
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* @policy: the policy to verify
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*
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* Validates a new CPUFreq policy. This function has to be called with
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* cpufreq_driver locked.
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*/
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static int longrun_verify_policy(struct cpufreq_policy *policy)
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{
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if (!policy)
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return -EINVAL;
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policy->cpu = 0;
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cpufreq_verify_within_limits(policy,
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policy->cpuinfo.min_freq,
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policy->cpuinfo.max_freq);
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if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) &&
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(policy->policy != CPUFREQ_POLICY_PERFORMANCE))
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return -EINVAL;
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return 0;
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}
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static unsigned int longrun_get(unsigned int cpu)
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{
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u32 eax, ebx, ecx, edx;
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if (cpu)
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return 0;
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cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
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pr_debug("cpuid eax is %u\n", eax);
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return eax * 1000;
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}
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/**
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* longrun_determine_freqs - determines the lowest and highest possible core frequency
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* @low_freq: an int to put the lowest frequency into
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* @high_freq: an int to put the highest frequency into
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*
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* Determines the lowest and highest possible core frequencies on this CPU.
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* This is necessary to calculate the performance percentage according to
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* TMTA rules:
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* performance_pctg = (target_freq - low_freq)/(high_freq - low_freq)
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*/
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static int __cpuinit longrun_determine_freqs(unsigned int *low_freq,
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unsigned int *high_freq)
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{
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u32 msr_lo, msr_hi;
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u32 save_lo, save_hi;
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u32 eax, ebx, ecx, edx;
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u32 try_hi;
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struct cpuinfo_x86 *c = &cpu_data(0);
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if (!low_freq || !high_freq)
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return -EINVAL;
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if (cpu_has(c, X86_FEATURE_LRTI)) {
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/* if the LongRun Table Interface is present, the
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* detection is a bit easier:
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* For minimum frequency, read out the maximum
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* level (msr_hi), write that into "currently
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* selected level", and read out the frequency.
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* For maximum frequency, read out level zero.
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*/
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/* minimum */
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rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi);
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wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi);
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rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
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*low_freq = msr_lo * 1000; /* to kHz */
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/* maximum */
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wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi);
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rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
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*high_freq = msr_lo * 1000; /* to kHz */
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pr_debug("longrun table interface told %u - %u kHz\n",
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*low_freq, *high_freq);
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if (*low_freq > *high_freq)
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*low_freq = *high_freq;
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return 0;
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}
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/* set the upper border to the value determined during TSC init */
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*high_freq = (cpu_khz / 1000);
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*high_freq = *high_freq * 1000;
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pr_debug("high frequency is %u kHz\n", *high_freq);
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/* get current borders */
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rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
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save_lo = msr_lo & 0x0000007F;
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save_hi = msr_hi & 0x0000007F;
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/* if current perf_pctg is larger than 90%, we need to decrease the
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* upper limit to make the calculation more accurate.
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*/
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cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
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/* try decreasing in 10% steps, some processors react only
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* on some barrier values */
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for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) {
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/* set to 0 to try_hi perf_pctg */
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msr_lo &= 0xFFFFFF80;
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msr_hi &= 0xFFFFFF80;
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msr_hi |= try_hi;
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wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
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/* read out current core MHz and current perf_pctg */
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cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
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/* restore values */
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wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi);
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}
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pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax);
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/* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
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* eqals
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* low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg)
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*
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* high_freq * perf_pctg is stored tempoarily into "ebx".
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*/
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ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */
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if ((ecx > 95) || (ecx == 0) || (eax < ebx))
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return -EIO;
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edx = ((eax - ebx) * 100) / (100 - ecx);
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*low_freq = edx * 1000; /* back to kHz */
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pr_debug("low frequency is %u kHz\n", *low_freq);
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if (*low_freq > *high_freq)
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*low_freq = *high_freq;
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return 0;
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}
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static int __cpuinit longrun_cpu_init(struct cpufreq_policy *policy)
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{
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int result = 0;
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/* capability check */
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if (policy->cpu != 0)
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return -ENODEV;
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/* detect low and high frequency */
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result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq);
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if (result)
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return result;
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/* cpuinfo and default policy values */
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policy->cpuinfo.min_freq = longrun_low_freq;
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policy->cpuinfo.max_freq = longrun_high_freq;
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policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
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longrun_get_policy(policy);
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return 0;
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}
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static struct cpufreq_driver longrun_driver = {
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.flags = CPUFREQ_CONST_LOOPS,
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.verify = longrun_verify_policy,
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.setpolicy = longrun_set_policy,
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.get = longrun_get,
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.init = longrun_cpu_init,
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.name = "longrun",
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.owner = THIS_MODULE,
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};
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/**
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* longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver
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*
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* Initializes the LongRun support.
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*/
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static int __init longrun_init(void)
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{
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struct cpuinfo_x86 *c = &cpu_data(0);
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if (c->x86_vendor != X86_VENDOR_TRANSMETA ||
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!cpu_has(c, X86_FEATURE_LONGRUN))
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return -ENODEV;
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return cpufreq_register_driver(&longrun_driver);
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}
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/**
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* longrun_exit - unregisters LongRun support
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*/
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static void __exit longrun_exit(void)
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{
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cpufreq_unregister_driver(&longrun_driver);
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}
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MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
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MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and "
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"Efficeon processors.");
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MODULE_LICENSE("GPL");
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module_init(longrun_init);
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module_exit(longrun_exit);
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