/*
* Intel SpeedStep SMI driver.
*
* (C) 2003 Hiroshi Miura <miura@da-cha.org>
*
* Licensed under the terms of the GNU GPL License version 2.
*
*/
/*********************************************************************
* SPEEDSTEP - DEFINITIONS *
*********************************************************************/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <asm/ist.h>
#include <asm/cpu_device_id.h>
#include "speedstep-lib.h"
/* speedstep system management interface port/command.
*
* These parameters are got from IST-SMI BIOS call.
* If user gives it, these are used.
*
*/
static int smi_port;
static int smi_cmd;
static unsigned int smi_sig;
/* info about the processor */
static enum speedstep_processor speedstep_processor;
/*
* There are only two frequency states for each processor. Values
* are in kHz for the time being.
*/
static struct cpufreq_frequency_table speedstep_freqs[] = {
{0, SPEEDSTEP_HIGH, 0},
{0, SPEEDSTEP_LOW, 0},
{0, 0, CPUFREQ_TABLE_END},
};
#define GET_SPEEDSTEP_OWNER 0
#define GET_SPEEDSTEP_STATE 1
#define SET_SPEEDSTEP_STATE 2
#define GET_SPEEDSTEP_FREQS 4
/* how often shall the SMI call be tried if it failed, e.g. because
* of DMA activity going on? */
#define SMI_TRIES 5
/**
* speedstep_smi_ownership
*/
static int speedstep_smi_ownership(void)
{
u32 command, result, magic, dummy;
u32 function = GET_SPEEDSTEP_OWNER;
unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
magic = virt_to_phys(magic_data);
pr_debug("trying to obtain ownership with command %x at port %x\n",
command, smi_port);
__asm__ __volatile__(
"push %%ebp\n"
"out %%al, (%%dx)\n"
"pop %%ebp\n"
: "=D" (result),
"=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
"=S" (dummy)
: "a" (command), "b" (function), "c" (0), "d" (smi_port),
"D" (0), "S" (magic)
: "memory"
);
pr_debug("result is %x\n", result);
return result;
}
/**
* speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
* @low: the low frequency value is placed here
* @high: the high frequency value is placed here
*
* Only available on later SpeedStep-enabled systems, returns false results or
* even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
* shows that the latter occurs if !(ist_info.event & 0xFFFF).
*/
static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
{
u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
u32 state = 0;
u32 function = GET_SPEEDSTEP_FREQS;
if (!(ist_info.event & 0xFFFF)) {
pr_debug("bug #1422 -- can't read freqs from BIOS\n");
return -ENODEV;
}
command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
pr_debug("trying to determine frequencies with command %x at port %x\n",
command, smi_port);
__asm__ __volatile__(
"push %%ebp\n"
"out %%al, (%%dx)\n"
"pop %%ebp"
: "=a" (result),
"=b" (high_mhz),
"=c" (low_mhz),
"=d" (state), "=D" (edi), "=S" (dummy)
: "a" (command),
"b" (function),
"c" (state),
"d" (smi_port), "S" (0), "D" (0)
);
pr_debug("result %x, low_freq %u, high_freq %u\n",
result, low_mhz, high_mhz);
/* abort if results are obviously incorrect... */
if ((high_mhz + low_mhz) < 600)
return -EINVAL;
*high = high_mhz * 1000;
*low = low_mhz * 1000;
return result;
}
/**
* speedstep_set_state - set the SpeedStep state
* @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
*
*/
static void speedstep_set_state(unsigned int state)
{
unsigned int result = 0, command, new_state, dummy;
unsigned long flags;
unsigned int function = SET_SPEEDSTEP_STATE;
unsigned int retry = 0;
if (state > 0x1)
return;
/* Disable IRQs */
preempt_disable();
local_irq_save(flags);
command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
pr_debug("trying to set frequency to state %u "
"with command %x at port %x\n",
state, command, smi_port);
do {
if (retry) {
/*
* We need to enable interrupts, otherwise the blockage
* won't resolve.
*
* We disable preemption so that other processes don't
* run. If other processes were running, they could
* submit more DMA requests, making the blockage worse.
*/
pr_debug("retry %u, previous result %u, waiting...\n",
retry, result);
local_irq_enable();
mdelay(retry * 50);
local_irq_disable();
}
retry++;
__asm__ __volatile__(
"push %%ebp\n"
"out %%al, (%%dx)\n"
"pop %%ebp"
: "=b" (new_state), "=D" (result),
"=c" (dummy), "=a" (dummy),
"=d" (dummy), "=S" (dummy)
: "a" (command), "b" (function), "c" (state),
"d" (smi_port), "S" (0), "D" (0)
);
} while ((new_state != state) && (retry <= SMI_TRIES));
/* enable IRQs */
local_irq_restore(flags);
preempt_enable();
if (new_state == state)
pr_debug("change to %u MHz succeeded after %u tries "
"with result %u\n",
(speedstep_freqs[new_state].frequency / 1000),
retry, result);
else
printk(KERN_ERR "cpufreq: change to state %u "
"failed with new_state %u and result %u\n",
state, new_state, result);
return;
}
/**
* speedstep_target - set a new CPUFreq policy
* @policy: new policy
* @index: index of new freq
*
* Sets a new CPUFreq policy/freq.
*/
static int speedstep_target(struct cpufreq_policy *policy, unsigned int index)
{
speedstep_set_state(index);
return 0;
}
static int speedstep_cpu_init(struct cpufreq_policy *policy)
{
int result;
unsigned int *low, *high;
/* capability check */
if (policy->cpu != 0)
return -ENODEV;
result = speedstep_smi_ownership();
if (result) {
pr_debug("fails in acquiring ownership of a SMI interface.\n");
return -EINVAL;
}
/* detect low and high frequency */
low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
result = speedstep_smi_get_freqs(low, high);
if (result) {
/* fall back to speedstep_lib.c dection mechanism:
* try both states out */
pr_debug("could not detect low and high frequencies "
"by SMI call.\n");
result = speedstep_get_freqs(speedstep_processor,
low, high,
NULL,
&speedstep_set_state);
if (result) {
pr_debug("could not detect two different speeds"
" -- aborting.\n");
return result;
} else
pr_debug("workaround worked.\n");
}
policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
return cpufreq_table_validate_and_show(policy, speedstep_freqs);
}
static unsigned int speedstep_get(unsigned int cpu)
{
if (cpu)
return -ENODEV;
return speedstep_get_frequency(speedstep_processor);
}
static int speedstep_resume(struct cpufreq_policy *policy)
{
int result = speedstep_smi_ownership();
if (result)
pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
return result;
}
static struct cpufreq_driver speedstep_driver = {
.name = "speedstep-smi",
.verify = cpufreq_generic_frequency_table_verify,
.target_index = speedstep_target,
.init = speedstep_cpu_init,
.get = speedstep_get,
.resume = speedstep_resume,
.attr = cpufreq_generic_attr,
};
static const struct x86_cpu_id ss_smi_ids[] = {
{ X86_VENDOR_INTEL, 6, 0xb, },
{ X86_VENDOR_INTEL, 6, 0x8, },
{ X86_VENDOR_INTEL, 15, 2 },
{}
};
#if 0
/* Not auto loaded currently */
MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
#endif
/**
* speedstep_init - initializes the SpeedStep CPUFreq driver
*
* Initializes the SpeedStep support. Returns -ENODEV on unsupported
* BIOS, -EINVAL on problems during initiatization, and zero on
* success.
*/
static int __init speedstep_init(void)
{
if (!x86_match_cpu(ss_smi_ids))
return -ENODEV;
speedstep_processor = speedstep_detect_processor();
switch (speedstep_processor) {
case SPEEDSTEP_CPU_PIII_T:
case SPEEDSTEP_CPU_PIII_C:
case SPEEDSTEP_CPU_PIII_C_EARLY:
break;
default:
speedstep_processor = 0;
}
if (!speedstep_processor) {
pr_debug("No supported Intel CPU detected.\n");
return -ENODEV;
}
pr_debug("signature:0x%.8x, command:0x%.8x, "
"event:0x%.8x, perf_level:0x%.8x.\n",
ist_info.signature, ist_info.command,
ist_info.event, ist_info.perf_level);
/* Error if no IST-SMI BIOS or no PARM
sig= 'ISGE' aka 'Intel Speedstep Gate E' */
if ((ist_info.signature != 0x47534943) && (
(smi_port == 0) || (smi_cmd == 0)))
return -ENODEV;
if (smi_sig == 1)
smi_sig = 0x47534943;
else
smi_sig = ist_info.signature;
/* setup smi_port from MODLULE_PARM or BIOS */
if ((smi_port > 0xff) || (smi_port < 0))
return -EINVAL;
else if (smi_port == 0)
smi_port = ist_info.command & 0xff;
if ((smi_cmd > 0xff) || (smi_cmd < 0))
return -EINVAL;
else if (smi_cmd == 0)
smi_cmd = (ist_info.command >> 16) & 0xff;
return cpufreq_register_driver(&speedstep_driver);
}
/**
* speedstep_exit - unregisters SpeedStep support
*
* Unregisters SpeedStep support.
*/
static void __exit speedstep_exit(void)
{
cpufreq_unregister_driver(&speedstep_driver);
}
module_param(smi_port, int, 0444);
module_param(smi_cmd, int, 0444);
module_param(smi_sig, uint, 0444);
MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
"-- Intel's default setting is 0xb2");
MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
"-- Intel's default setting is 0x82");
MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
"SMI interface.");
MODULE_AUTHOR("Hiroshi Miura");
MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
MODULE_LICENSE("GPL");
module_init(speedstep_init);
module_exit(speedstep_exit);
