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kernel/drivers/cpufreq/powernow-k6.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* 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.
*
* 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/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 */
static unsigned int busfreq; /* FSB, in 10 kHz */
static unsigned int max_multiplier;
static unsigned int param_busfreq = 0;
static unsigned int param_max_multiplier = 0;
module_param_named(max_multiplier, param_max_multiplier, uint, S_IRUGO);
MODULE_PARM_DESC(max_multiplier, "Maximum multiplier (allowed values: 20 30 35 40 45 50 55 60)");
module_param_named(bus_frequency, param_busfreq, uint, S_IRUGO);
MODULE_PARM_DESC(bus_frequency, "Bus frequency in kHz");
/* Clock ratio multiplied by 10 - see table 27 in AMD#23446 */
static struct cpufreq_frequency_table clock_ratio[] = {
{0, 60, /* 110 -> 6.0x */ 0},
{0, 55, /* 011 -> 5.5x */ 0},
{0, 50, /* 001 -> 5.0x */ 0},
{0, 45, /* 000 -> 4.5x */ 0},
{0, 40, /* 010 -> 4.0x */ 0},
{0, 35, /* 111 -> 3.5x */ 0},
{0, 30, /* 101 -> 3.0x */ 0},
{0, 20, /* 100 -> 2.0x */ 0},
{0, 0, CPUFREQ_TABLE_END}
};
static const u8 index_to_register[8] = { 6, 3, 1, 0, 2, 7, 5, 4 };
static const u8 register_to_index[8] = { 3, 2, 4, 1, 7, 6, 0, 5 };
static const struct {
unsigned freq;
unsigned mult;
} usual_frequency_table[] = {
{ 350000, 35 }, // 100 * 3.5
{ 400000, 40 }, // 100 * 4
{ 450000, 45 }, // 100 * 4.5
{ 475000, 50 }, // 95 * 5
{ 500000, 50 }, // 100 * 5
{ 506250, 45 }, // 112.5 * 4.5
{ 533500, 55 }, // 97 * 5.5
{ 550000, 55 }, // 100 * 5.5
{ 562500, 50 }, // 112.5 * 5
{ 570000, 60 }, // 95 * 6
{ 600000, 60 }, // 100 * 6
{ 618750, 55 }, // 112.5 * 5.5
{ 660000, 55 }, // 120 * 5.5
{ 675000, 60 }, // 112.5 * 6
{ 720000, 60 }, // 120 * 6
};
#define FREQ_RANGE 3000
/**
* 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)
{
unsigned long invalue = 0;
u32 msrval;
local_irq_disable();
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 */
local_irq_enable();
return clock_ratio[register_to_index[(invalue >> 5)&7]].driver_data;
}
static void powernow_k6_set_cpu_multiplier(unsigned int best_i)
{
unsigned long outvalue, invalue;
unsigned long msrval;
unsigned long cr0;
/* we now need to transform best_i to the BVC format, see AMD#23446 */
/*
* The processor doesn't respond to inquiry cycles while changing the
* frequency, so we must disable cache.
*/
local_irq_disable();
cr0 = read_cr0();
write_cr0(cr0 | X86_CR0_CD);
wbinvd();
outvalue = (1<<12) | (1<<10) | (1<<9) | (index_to_register[best_i]<<5);
msrval = POWERNOW_IOPORT + 0x1;
wrmsr(MSR_K6_EPMR, msrval, 0); /* enable the PowerNow port */
invalue = inl(POWERNOW_IOPORT + 0x8);
invalue = invalue & 0x1f;
outvalue = outvalue | invalue;
outl(outvalue, (POWERNOW_IOPORT + 0x8));
msrval = POWERNOW_IOPORT + 0x0;
wrmsr(MSR_K6_EPMR, msrval, 0); /* disable it again */
write_cr0(cr0);
local_irq_enable();
}
/**
* 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)
{
if (clock_ratio[best_i].driver_data > max_multiplier) {
pr_err("invalid target frequency\n");
return -EINVAL;
}
powernow_k6_set_cpu_multiplier(best_i);
return 0;
}
static int powernow_k6_cpu_init(struct cpufreq_policy *policy)
{
struct cpufreq_frequency_table *pos;
unsigned int i, f;
unsigned khz;
if (policy->cpu != 0)
return -ENODEV;
max_multiplier = 0;
khz = cpu_khz;
for (i = 0; i < ARRAY_SIZE(usual_frequency_table); i++) {
if (khz >= usual_frequency_table[i].freq - FREQ_RANGE &&
khz <= usual_frequency_table[i].freq + FREQ_RANGE) {
khz = usual_frequency_table[i].freq;
max_multiplier = usual_frequency_table[i].mult;
break;
}
}
if (param_max_multiplier) {
cpufreq_for_each_entry(pos, clock_ratio)
if (pos->driver_data == param_max_multiplier) {
max_multiplier = param_max_multiplier;
goto have_max_multiplier;
}
pr_err("invalid max_multiplier parameter, valid parameters 20, 30, 35, 40, 45, 50, 55, 60\n");
return -EINVAL;
}
if (!max_multiplier) {
pr_warn("unknown frequency %u, cannot determine current multiplier\n",
khz);
pr_warn("use module parameters max_multiplier and bus_frequency\n");
return -EOPNOTSUPP;
}
have_max_multiplier:
param_max_multiplier = max_multiplier;
if (param_busfreq) {
if (param_busfreq >= 50000 && param_busfreq <= 150000) {
busfreq = param_busfreq / 10;
goto have_busfreq;
}
pr_err("invalid bus_frequency parameter, allowed range 50000 - 150000 kHz\n");
return -EINVAL;
}
busfreq = khz / max_multiplier;
have_busfreq:
param_busfreq = busfreq * 10;
/* table init */
cpufreq_for_each_entry(pos, clock_ratio) {
f = pos->driver_data;
if (f > max_multiplier)
pos->frequency = CPUFREQ_ENTRY_INVALID;
else
pos->frequency = busfreq * f;
}
/* cpuinfo and default policy values */
policy->cpuinfo.transition_latency = 500000;
policy->freq_table = clock_ratio;
return 0;
}
static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
{
unsigned int i;
for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
if (clock_ratio[i].driver_data == max_multiplier) {
struct cpufreq_freqs freqs;
freqs.old = policy->cur;
freqs.new = clock_ratio[i].frequency;
freqs.flags = 0;
cpufreq_freq_transition_begin(policy, &freqs);
powernow_k6_target(policy, i);
cpufreq_freq_transition_end(policy, &freqs, 0);
break;
}
}
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_MATCH_VENDOR_FAM_MODEL(AMD, 5, 12, NULL),
X86_MATCH_VENDOR_FAM_MODEL(AMD, 5, 13, NULL),
{}
};
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!")) {
pr_info("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, "
"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);
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