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