OK, I realize cpu_khz should not be constant. I wrote a cpufreq driver
for Toshiba laptops that has two CPU speeds (1/2 and full) and that is
managed via SMM. Can anyone tell me why cpu_khz occasionally doubles
itself while the driver is in use? It starts at ~120000, then doubles
to ~240000, then to ~480000, etc. However, this is over ~15 loads and
unloads of the cpufreq target driver. Small cpu_khz variations would
not bother anything wrt the cpufreq driver, but this is just plain
incorrect for things like /proc/cpuinfo which also use cpu_khz.
Is this a TSC issue (maybe related to SMM) or am I just doing something
in the wrong place in the driver?
Attached is the cpufreq part of the code, just a testing version.
--
Ryan Underwood, <[email protected]>
/*
* toshiba_freq.c: cpufreq driver for Toshiba SCI (non-Speedstep) laptops
*
* Copyright (C) 2006 Ryan Underwood <[email protected]>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Based on sc520_freq.c
*
* 2006-09-11: - initial revision
*/
/* NOTE: currently this should drag in toshiba.ko which checks for the
* appropriate hardware in its init function. Things will be different when
* ACPI instead of the SMM driver is used as the SCI access method. */
/* XXX, error handling on all tosh_scihci calls!! And graceful exit! */
/* FIXME: Fan and LCD brightness are variable on some systems */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/toshiba.h>
#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "toshiba_freq", msg)
static u32 original_cpustate;
static u32 original_cache;
static u32 original_brightness;
static u32 original_fan;
/* Store this locally to avoid a SMM round trip to obtain it */
static u32 current_cpustate;
static int control_cpucache = 1;
static int control_fan = 1;
static int control_lcd;
module_param_named(cpucache, control_cpucache, int, 1);
MODULE_PARM_DESC(fn, "Allow CPUFreq to enable/disable CPU cache");
module_param_named(fan, control_fan, int, 1);
MODULE_PARM_DESC(fn, "Allow CPUFreq to control the system fan");
module_param_named(lcd, control_lcd, int, 0);
MODULE_PARM_DESC(fn, "Allow CPUFreq to control LCD brightness");
/* Index corresponds to the SCI CPU speed state (0 or 1) */
static struct cpufreq_frequency_table toshiba_freq_table[] = {
{0, 0}, /* slow (low) */
{1, 0}, /* fast (high) */
{0, CPUFREQ_TABLE_END},
};
static unsigned int toshiba_freq_get_cpu_frequency(unsigned int cpu)
{
#if 0
unsigned int val;
tosh_scihci_get(0, SCI_PROCESSING, &val);
return val;
#else
return toshiba_freq_table[current_cpustate].frequency;
#endif
}
static void toshiba_freq_set_cpu_state (unsigned int state)
{
struct cpufreq_freqs freqs;
freqs.old = toshiba_freq_get_cpu_frequency(0);
freqs.new = toshiba_freq_table[state].frequency;
freqs.cpu = 0;
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
dprintk("attempting to set frequency to %i kHz\n",
toshiba_freq_table[state].frequency);
if (state == 0) { /* slow */
if (control_fan)
tosh_scihci_set(HCI_SET, HCI_FAN, HCI_DISABLE);
if (control_lcd)
tosh_scihci_set(0, SCI_LCD_BRIGHTNESS, SCI_SEMI_BRIGHT);
if (control_cpucache)
tosh_scihci_set(0, SCI_CPU_CACHE, SCI_OFF);
tosh_scihci_set(0, SCI_PROCESSING, SCI_LOW);
}
else { /* fast */
if (control_fan)
tosh_scihci_set(HCI_SET, HCI_FAN, HCI_ENABLE);
if (control_lcd)
tosh_scihci_set(0, SCI_LCD_BRIGHTNESS, SCI_BRIGHT);
if (control_cpucache)
tosh_scihci_set(0, SCI_CPU_CACHE, SCI_ON);
tosh_scihci_set(0, SCI_PROCESSING, SCI_HIGH);
}
current_cpustate = toshiba_freq_table[state].index;
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
};
static int toshiba_freq_verify (struct cpufreq_policy *policy)
{
return cpufreq_frequency_table_verify(policy, &toshiba_freq_table[0]);
}
static int toshiba_freq_target (struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
unsigned int newstate = 0;
if (cpufreq_frequency_table_target(policy, toshiba_freq_table, target_freq, relation, &newstate))
return -EINVAL;
toshiba_freq_set_cpu_state(newstate);
return 0;
}
/*
* Module init and exit code
*/
static int toshiba_freq_cpu_init(struct cpufreq_policy *policy)
{
int result;
/* Fill out the frequency table
* Toshiba SCI has two modes, "slow" and "fast" where "fast" is
* the nominal CPU speed, and "slow" is half speed */
/* Prevent userspace from using /dev/toshiba to frob the CPU speed */
tosh_cpufreq_in_control = 1;
/* It would be nice if we could obtain the CPU nominal MHz rating from
* the firmware somehow. Oh well. We use cpu_khz instead since it is
* close enough for our needs. */
/* FIXME why is cpu_khz doubling? */
toshiba_freq_table[0].frequency = cpu_khz / 2;
toshiba_freq_table[1].frequency = cpu_khz;
/* cpuinfo and default policy values */
policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
policy->cpuinfo.transition_latency = 5000000; /* 5ms, estimated max SMI/SMM latency */
policy->cur = toshiba_freq_get_cpu_frequency(0);
result = cpufreq_frequency_table_cpuinfo(policy, toshiba_freq_table);
if (result)
return (result);
cpufreq_frequency_table_get_attr(toshiba_freq_table, policy->cpu);
return 0;
}
static int toshiba_freq_cpu_exit(struct cpufreq_policy *policy)
{
cpufreq_frequency_table_put_attr(policy->cpu);
/* Restore the old configuration */
if (control_fan)
tosh_scihci_set(HCI_SET, HCI_FAN, original_fan);
if (control_lcd)
tosh_scihci_set(0, SCI_LCD_BRIGHTNESS, original_brightness);
if (control_cpucache)
tosh_scihci_set(0, SCI_CPU_CACHE, original_cache);
tosh_scihci_set(0, SCI_PROCESSING, original_cpustate);
/* Allow userspace to control CPU via SCI again */
tosh_cpufreq_in_control = 0;
return 0;
}
static struct freq_attr* toshiba_freq_attr[] = {
&cpufreq_freq_attr_scaling_available_freqs,
NULL,
};
static struct cpufreq_driver toshiba_freq_driver = {
.get = toshiba_freq_get_cpu_frequency,
.verify = toshiba_freq_verify,
.target = toshiba_freq_target,
.init = toshiba_freq_cpu_init,
.exit = toshiba_freq_cpu_exit,
.name = "toshiba_freq",
.owner = THIS_MODULE,
.attr = toshiba_freq_attr,
};
static int __init toshiba_freq_init(void)
{
/* Note: At least some ACPI machines do not allow the SMM driver to
* modify the CPU frequency. Here, we will read all the settings we
* are interested in and attempt to set their values, as a test that we
* are actually in control of the hardware. */
char buf[100];
/* CPU speed state */
if (tosh_scihci_get(0, SCI_PROCESSING, &original_cpustate) ||
tosh_scihci_set(0, SCI_PROCESSING, original_cpustate))
return -ENODEV;
sprintf(buf, "toshiba_freq.c: Managing CPU");
/* CPU cache */
if (control_cpucache) {
if (tosh_scihci_get(0, SCI_CPU_CACHE, &original_cache) ||
tosh_scihci_set(0, SCI_CPU_CACHE, original_cache))
return -ENODEV;
strcat(buf, ", L2 cache");
}
/* Fan */
if (control_fan) {
if (tosh_scihci_get(HCI_GET, HCI_FAN, &original_fan) ||
tosh_scihci_set(HCI_SET, HCI_FAN, original_fan))
return -ENODEV;
strcat(buf, ", system fan");
}
/* Display brightness */
if (control_lcd) {
if (tosh_scihci_get(0, SCI_LCD_BRIGHTNESS, &original_brightness) ||
tosh_scihci_set(0, SCI_LCD_BRIGHTNESS, original_brightness))
return -ENODEV;
strcat(buf, ", LCD");
}
printk("%s\n", buf);
current_cpustate = original_cpustate;
return cpufreq_register_driver(&toshiba_freq_driver);
}
static void __exit toshiba_freq_exit(void)
{
cpufreq_unregister_driver(&toshiba_freq_driver);
}
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Ryan Underwood <[email protected]>");
MODULE_DESCRIPTION("cpufreq driver for Toshiba SCI (non-Speedstep) laptops");
module_init(toshiba_freq_init);
module_exit(toshiba_freq_exit);
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