/*
* This file was based upon code in Powertweak Linux (http://powertweak.sf.net)
* (C) 2000-2003 Dave Jones, Arjan van de Ven, Janne Pänkälä,
* Dominik Brodowski.
*
* 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/ioport.h>
#include <linux/timex.h>
#include <linux/io.h>
#include <asm/cpu_device_id.h>
#include <asm/msr.h>
#define POWERNOW_IOPORT 0xfff0 /* it doesn't matter where, as long
as it is unused */
#define PFX "powernow-k6: "
static unsigned int busfreq; /* FSB, in 10 kHz */
static unsigned int max_multiplier;
/* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
static struct cpufreq_frequency_table clock_ratio[] = {
{45, /* 000 -> 4.5x */ 0},
{50, /* 001 -> 5.0x */ 0},
{40, /* 010 -> 4.0x */ 0},
{55, /* 011 -> 5.5x */ 0},
{20, /* 100 -> 2.0x */ 0},
{30, /* 101 -> 3.0x */ 0},
{60, /* 110 -> 6.0x */ 0},
{35, /* 111 -> 3.5x */ 0},
{0, CPUFREQ_TABLE_END}
};
/**
* powernow_k6_get_cpu_multiplier - returns the current FSB multiplier
*
* Returns the current setting of the frequency multiplier. Core clock
* speed is frequency of the Front-Side Bus multiplied with this value.
*/
static int powernow_k6_get_cpu_multiplier(void)
{
u64 invalue = 0;
u32 msrval;
msrval = POWERNOW_IOPORT + 0x1;
wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
invalue = inl(POWERNOW_IOPORT + 0x8);
msrval = POWERNOW_IOPORT + 0x0;
wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
return clock_ratio[(invalue >> 5)&7].driver_data;
}
/**
* powernow_k6_target - set the PowerNow! multiplier
* @best_i: clock_ratio[best_i] is the target multiplier
*
* Tries to change the PowerNow! multiplier
*/
static int powernow_k6_target(struct cpufreq_policy *policy,
unsigned int best_i)
{
unsigned long outvalue = 0, invalue = 0;
unsigned long msrval;
struct cpufreq_freqs freqs;
if (clock_ratio[best_i].driver_data > max_multiplier) {
printk(KERN_ERR PFX "invalid target frequency\n");
return -EINVAL;
}
freqs.old = busfreq * powernow_k6_get_cpu_multiplier();
freqs.new = busfreq * clock_ratio[best_i].driver_data;
cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
/* we now need to transform best_i to the BVC format, see AMD#23446 */
outvalue = (1<<12) | (1<<10) | (1<<9) | (best_i<<5);
msrval = POWERNOW_IOPORT + 0x1;
wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
invalue = inl(POWERNOW_IOPORT + 0x8);
invalue = invalue & 0xf;
outvalue = outvalue | invalue;
outl(outvalue , (POWERNOW_IOPORT + 0x8));
msrval = POWERNOW_IOPORT + 0x0;
wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
return 0;
}
static int powernow_k6_cpu_init(struct cpufreq_policy *policy)
{
unsigned int i, f;
if (policy->cpu != 0)
return -ENODEV;
/* get frequencies */
max_multiplier = powernow_k6_get_cpu_multiplier();
busfreq = cpu_khz / max_multiplier;
/* table init */
for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
f = clock_ratio[i].driver_data;
if (f > max_multiplier)
clock_ratio[i].frequency = CPUFREQ_ENTRY_INVALID;
else
clock_ratio[i].frequency = busfreq * f;
}
/* cpuinfo and default policy values */
policy->cpuinfo.transition_latency = 200000;
return cpufreq_table_validate_and_show(policy, clock_ratio);
}
static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
{
unsigned int i;
for (i = 0; i < 8; i++) {
if (i == max_multiplier)
powernow_k6_target(policy, i);
}
cpufreq_frequency_table_put_attr(policy->cpu);
return 0;
}
static unsigned int powernow_k6_get(unsigned int cpu)
{
unsigned int ret;
ret = (busfreq * powernow_k6_get_cpu_multiplier());
return ret;
}
static struct cpufreq_driver powernow_k6_driver = {
.verify = cpufreq_generic_frequency_table_verify,
.target_index = powernow_k6_target,
.init = powernow_k6_cpu_init,
.exit = powernow_k6_cpu_exit,
.get = powernow_k6_get,
.name = "powernow-k6",
.attr = cpufreq_generic_attr,
};
static const struct x86_cpu_id powernow_k6_ids[] = {
{ X86_VENDOR_AMD, 5, 12 },
{ X86_VENDOR_AMD, 5, 13 },
{}
};
MODULE_DEVICE_TABLE(x86cpu, powernow_k6_ids);
/**
* powernow_k6_init - initializes the k6 PowerNow! CPUFreq driver
*
* Initializes the K6 PowerNow! support. Returns -ENODEV on unsupported
* devices, -EINVAL or -ENOMEM on problems during initiatization, and zero
* on success.
*/
static int __init powernow_k6_init(void)
{
if (!x86_match_cpu(powernow_k6_ids))
return -ENODEV;
if (!request_region(POWERNOW_IOPORT, 16, "PowerNow!")) {
printk(KERN_INFO PFX "PowerNow IOPORT region already used.\n");
return -EIO;
}
if (cpufreq_register_driver(&powernow_k6_driver)) {
release_region(POWERNOW_IOPORT, 16);
return -EINVAL;
}
return 0;
}
/**
* powernow_k6_exit - unregisters AMD K6-2+/3+ PowerNow! support
*
* Unregisters AMD K6-2+ / K6-3+ PowerNow! support.
*/
static void __exit powernow_k6_exit(void)
{
cpufreq_unregister_driver(&powernow_k6_driver);
release_region(POWERNOW_IOPORT, 16);
}
MODULE_AUTHOR("Arjan van de Ven, Dave Jones <davej@redhat.com>, "
"Dominik Brodowski <linux@brodo.de>");
MODULE_DESCRIPTION("PowerNow! driver for AMD K6-2+ / K6-3+ processors.");
MODULE_LICENSE("GPL");
module_init(powernow_k6_init);
module_exit(powernow_k6_exit);
