/*
* processor_throttling.c - Throttling submodule of the ACPI processor driver
*
* Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
* Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
* Copyright (C) 2004 Dominik Brodowski <linux@brodo.de>
* Copyright (C) 2004 Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
* - Added processor hotplug support
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* 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.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <acpi/acpi_bus.h>
#include <acpi/processor.h>
#define ACPI_PROCESSOR_COMPONENT 0x01000000
#define ACPI_PROCESSOR_CLASS "processor"
#define ACPI_PROCESSOR_DRIVER_NAME "ACPI Processor Driver"
#define _COMPONENT ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("acpi_processor")
/* --------------------------------------------------------------------------
Throttling Control
-------------------------------------------------------------------------- */
static int acpi_processor_get_throttling(struct acpi_processor *pr)
{
int state = 0;
u32 value = 0;
u32 duty_mask = 0;
u32 duty_value = 0;
ACPI_FUNCTION_TRACE("acpi_processor_get_throttling");
if (!pr)
return_VALUE(-EINVAL);
if (!pr->flags.throttling)
return_VALUE(-ENODEV);
pr->throttling.state = 0;
duty_mask = pr->throttling.state_count - 1;
duty_mask <<= pr->throttling.duty_offset;
local_irq_disable();
value = inl(pr->throttling.address);
/*
* Compute the current throttling state when throttling is enabled
* (bit 4 is on).
*/
if (value & 0x10) {
duty_value = value & duty_mask;
duty_value >>= pr->throttling.duty_offset;
if (duty_value)
state = pr->throttling.state_count - duty_value;
}
pr->throttling.state = state;
local_irq_enable();
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"Throttling state is T%d (%d%% throttling applied)\n",
state, pr->throttling.states[state].performance));
return_VALUE(0);
}
int acpi_processor_set_throttling(struct acpi_processor *pr, int state)
{
u32 value = 0;
u32 duty_mask = 0;
u32 duty_value = 0;
ACPI_FUNCTION_TRACE("acpi_processor_set_throttling");
if (!pr)
return_VALUE(-EINVAL);
if ((state < 0) || (state > (pr->throttling.state_count - 1)))
return_VALUE(-EINVAL);
if (!pr->flags.throttling)
return_VALUE(-ENODEV);
if (state == pr->throttling.state)
return_VALUE(0);
/*
* Calculate the duty_value and duty_mask.
*/
if (state) {
duty_value = pr->throttling.state_count - state;
duty_value <<= pr->throttling.duty_offset;
/* Used to clear all duty_value bits */
duty_mask = pr->throttling.state_count - 1;
duty_mask <<= acpi_fadt.duty_offset;
duty_mask = ~duty_mask;
}
local_irq_disable();
/*
* Disable throttling by writing a 0 to bit 4. Note that we must
* turn it off before you can change the duty_value.
*/
value = inl(pr->throttling.address);
if (value & 0x10) {
value &= 0xFFFFFFEF;
outl(value, pr->throttling.address);
}
/*
* Write the new duty_value and then enable throttling. Note
* that a state value of 0 leaves throttling disabled.
*/
if (state) {
value &= duty_mask;
value |= duty_value;
outl(value, pr->throttling.address);
value |= 0x00000010;
outl(value, pr->throttling.address);
}
pr->throttling.state = state;
local_irq_enable();
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"Throttling state set to T%d (%d%%)\n", state,
(pr->throttling.states[state].performance ? pr->
throttling.states[state].performance / 10 : 0)));
return_VALUE(0);
}
int acpi_processor_get_throttling_info(struct acpi_processor *pr)
{
int result = 0;
int step = 0;
int i = 0;
ACPI_FUNCTION_TRACE("acpi_processor_get_throttling_info");
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"pblk_address[0x%08x] duty_offset[%d] duty_width[%d]\n",
pr->throttling.address,
pr->throttling.duty_offset,
pr->throttling.duty_width));
if (!pr)
return_VALUE(-EINVAL);
/* TBD: Support ACPI 2.0 objects */
if (!pr->throttling.address) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n"));
return_VALUE(0);
} else if (!pr->throttling.duty_width) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling states\n"));
return_VALUE(0);
}
/* TBD: Support duty_cycle values that span bit 4. */
else if ((pr->throttling.duty_offset + pr->throttling.duty_width) > 4) {
ACPI_DEBUG_PRINT((ACPI_DB_WARN, "duty_cycle spans bit 4\n"));
return_VALUE(0);
}
/*
* PIIX4 Errata: We don't support throttling on the original PIIX4.
* This shouldn't be an issue as few (if any) mobile systems ever
* used this part.
*/
if (errata.piix4.throttle) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"Throttling not supported on PIIX4 A- or B-step\n"));
return_VALUE(0);
}
pr->throttling.state_count = 1 << acpi_fadt.duty_width;
/*
* Compute state values. Note that throttling displays a linear power/
* performance relationship (at 50% performance the CPU will consume
* 50% power). Values are in 1/10th of a percent to preserve accuracy.
*/
step = (1000 / pr->throttling.state_count);
for (i = 0; i < pr->throttling.state_count; i++) {
pr->throttling.states[i].performance = step * i;
pr->throttling.states[i].power = step * i;
}
ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d throttling states\n",
pr->throttling.state_count));
pr->flags.throttling = 1;
/*
* Disable throttling (if enabled). We'll let subsequent policy (e.g.
* thermal) decide to lower performance if it so chooses, but for now
* we'll crank up the speed.
*/
result = acpi_processor_get_throttling(pr);
if (result)
goto end;
if (pr->throttling.state) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"Disabling throttling (was T%d)\n",
pr->throttling.state));
result = acpi_processor_set_throttling(pr, 0);
if (result)
goto end;
}
end:
if (result)
pr->flags.throttling = 0;
return_VALUE(result);
}
/* proc interface */
static int acpi_processor_throttling_seq_show(struct seq_file *seq,
void *offset)
{
struct acpi_processor *pr = (struct acpi_processor *)seq->private;
int i = 0;
int result = 0;
ACPI_FUNCTION_TRACE("acpi_processor_throttling_seq_show");
if (!pr)
goto end;
if (!(pr->throttling.state_count > 0)) {
seq_puts(seq, "<not supported>\n");
goto end;
}
result = acpi_processor_get_throttling(pr);
if (result) {
seq_puts(seq,
"Could not determine current throttling state.\n");
goto end;
}
seq_printf(seq, "state count: %d\n"
"active state: T%d\n",
pr->throttling.state_count, pr->throttling.state);
seq_puts(seq, "states:\n");
for (i = 0; i < pr->throttling.state_count; i++)
seq_printf(seq, " %cT%d: %02d%%\n",
(i == pr->throttling.state ? '*' : ' '), i,
(pr->throttling.states[i].performance ? pr->
throttling.states[i].performance / 10 : 0));
end:
return_VALUE(0);
}
static int acpi_processor_throttling_open_fs(struct inode *inode,
struct file *file)
{
return single_open(file, acpi_processor_throttling_seq_show,
PDE(inode)->data);
}
ssize_t acpi_processor_write_throttling(struct file * file,
const char __user * buffer,
size_t count, loff_t * data)
{
int result = 0;
struct seq_file *m = (struct seq_file *)file->private_data;
struct acpi_processor *pr = (struct acpi_processor *)m->private;
char state_string[12] = { '\0' };
ACPI_FUNCTION_TRACE("acpi_processor_write_throttling");
if (!pr || (count > sizeof(state_string) - 1))
return_VALUE(-EINVAL);
if (copy_from_user(state_string, buffer, count))
return_VALUE(-EFAULT);
state_string[count] = '\0';
result = acpi_processor_set_throttling(pr,
simple_strtoul(state_string,
NULL, 0));
if (result)
return_VALUE(result);
return_VALUE(count);
}
struct file_operations acpi_processor_throttling_fops = {
.open = acpi_processor_throttling_open_fs,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
