kernel-fxtec-pro1x/arch/x86/kernel/cpu/cpufreq/speedstep-smi.c
Stephan Diestelhorst c6e8256a7b x86, cpufreq: fix Speedfreq-SMI call that clobbers ECX
I have found that using SMI to change the cpu's frequency on my DELL
Latitude L400 clobbers the ECX register in speedstep_set_state, causing
unneccessary retries because the "state" variable has changed silently (GCC
assumes it is still present in ECX).

play safe and avoid gcc caching any register across IO port accesses
that trigger SMIs.

Signed-off by: <Stephan.Diestelhorst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-26 22:23:40 +01:00

432 lines
11 KiB
C

/*
* 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/slab.h>
#include <linux/delay.h>
#include <asm/ist.h>
#include <asm/io.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 = 0;
static int smi_cmd = 0;
static unsigned int smi_sig = 0;
/* info about the processor */
static unsigned int speedstep_processor = 0;
/*
* There are only two frequency states for each processor. Values
* are in kHz for the time being.
*/
static struct cpufreq_frequency_table speedstep_freqs[] = {
{SPEEDSTEP_HIGH, 0},
{SPEEDSTEP_LOW, 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
#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "speedstep-smi", msg)
/**
* 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);
dprintk("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"
);
dprintk("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)) {
dprintk("bug #1422 -- can't read freqs from BIOS\n");
return -ENODEV;
}
command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
dprintk("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)
);
dprintk("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_get_state - set the SpeedStep state
* @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
*
*/
static int speedstep_get_state (void)
{
u32 function=GET_SPEEDSTEP_STATE;
u32 result, state, edi, command, dummy;
command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
dprintk("trying to determine current setting with command %x at port %x\n", command, smi_port);
__asm__ __volatile__(
"push %%ebp\n"
"out %%al, (%%dx)\n"
"pop %%ebp\n"
: "=a" (result), "=b" (state), "=D" (edi), "=c" (dummy), "=d" (dummy), "=S" (dummy)
: "a" (command), "b" (function), "c" (0), "d" (smi_port), "S" (0), "D" (0)
);
dprintk("state is %x, result is %x\n", state, result);
return (state & 1);
}
/**
* 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 */
local_irq_save(flags);
command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
dprintk("trying to set frequency to state %u with command %x at port %x\n", state, command, smi_port);
do {
if (retry) {
dprintk("retry %u, previous result %u, waiting...\n", retry, result);
mdelay(retry * 50);
}
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);
if (new_state == state) {
dprintk("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
* @target_freq: new freq
* @relation:
*
* Sets a new CPUFreq policy/freq.
*/
static int speedstep_target (struct cpufreq_policy *policy,
unsigned int target_freq, unsigned int relation)
{
unsigned int newstate = 0;
struct cpufreq_freqs freqs;
if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0], target_freq, relation, &newstate))
return -EINVAL;
freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
freqs.new = speedstep_freqs[newstate].frequency;
freqs.cpu = 0; /* speedstep.c is UP only driver */
if (freqs.old == freqs.new)
return 0;
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
speedstep_set_state(newstate);
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
return 0;
}
/**
* speedstep_verify - verifies a new CPUFreq policy
* @policy: new policy
*
* Limit must be within speedstep_low_freq and speedstep_high_freq, with
* at least one border included.
*/
static int speedstep_verify (struct cpufreq_policy *policy)
{
return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
}
static int speedstep_cpu_init(struct cpufreq_policy *policy)
{
int result;
unsigned int speed,state;
/* capability check */
if (policy->cpu != 0)
return -ENODEV;
result = speedstep_smi_ownership();
if (result) {
dprintk("fails in aquiring ownership of a SMI interface.\n");
return -EINVAL;
}
/* detect low and high frequency */
result = speedstep_smi_get_freqs(&speedstep_freqs[SPEEDSTEP_LOW].frequency,
&speedstep_freqs[SPEEDSTEP_HIGH].frequency);
if (result) {
/* fall back to speedstep_lib.c dection mechanism: try both states out */
dprintk("could not detect low and high frequencies by SMI call.\n");
result = speedstep_get_freqs(speedstep_processor,
&speedstep_freqs[SPEEDSTEP_LOW].frequency,
&speedstep_freqs[SPEEDSTEP_HIGH].frequency,
NULL,
&speedstep_set_state);
if (result) {
dprintk("could not detect two different speeds -- aborting.\n");
return result;
} else
dprintk("workaround worked.\n");
}
/* get current speed setting */
state = speedstep_get_state();
speed = speedstep_freqs[state].frequency;
dprintk("currently at %s speed setting - %i MHz\n",
(speed == speedstep_freqs[SPEEDSTEP_LOW].frequency) ? "low" : "high",
(speed / 1000));
/* cpuinfo and default policy values */
policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
policy->cur = speed;
result = cpufreq_frequency_table_cpuinfo(policy, speedstep_freqs);
if (result)
return (result);
cpufreq_frequency_table_get_attr(speedstep_freqs, policy->cpu);
return 0;
}
static int speedstep_cpu_exit(struct cpufreq_policy *policy)
{
cpufreq_frequency_table_put_attr(policy->cpu);
return 0;
}
static unsigned int speedstep_get(unsigned int cpu)
{
if (cpu)
return -ENODEV;
return speedstep_get_processor_frequency(speedstep_processor);
}
static int speedstep_resume(struct cpufreq_policy *policy)
{
int result = speedstep_smi_ownership();
if (result)
dprintk("fails in re-aquiring ownership of a SMI interface.\n");
return result;
}
static struct freq_attr* speedstep_attr[] = {
&cpufreq_freq_attr_scaling_available_freqs,
NULL,
};
static struct cpufreq_driver speedstep_driver = {
.name = "speedstep-smi",
.verify = speedstep_verify,
.target = speedstep_target,
.init = speedstep_cpu_init,
.exit = speedstep_cpu_exit,
.get = speedstep_get,
.resume = speedstep_resume,
.owner = THIS_MODULE,
.attr = speedstep_attr,
};
/**
* 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)
{
speedstep_processor = speedstep_detect_processor();
switch (speedstep_processor) {
case SPEEDSTEP_PROCESSOR_PIII_T:
case SPEEDSTEP_PROCESSOR_PIII_C:
case SPEEDSTEP_PROCESSOR_PIII_C_EARLY:
break;
default:
speedstep_processor = 0;
}
if (!speedstep_processor) {
dprintk ("No supported Intel CPU detected.\n");
return -ENODEV;
}
dprintk("signature:0x%.8lx, command:0x%.8lx, event:0x%.8lx, perf_level:0x%.8lx.\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);