338 lines
8.4 KiB
C
338 lines
8.4 KiB
C
/*
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* processor_throttling.c - Throttling submodule of the ACPI processor driver
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*
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* Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
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* Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
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* Copyright (C) 2004 Dominik Brodowski <linux@brodo.de>
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* Copyright (C) 2004 Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
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* - Added processor hotplug support
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*
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or (at
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* your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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*
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/cpufreq.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <asm/io.h>
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#include <asm/uaccess.h>
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#include <acpi/acpi_bus.h>
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#include <acpi/processor.h>
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#define ACPI_PROCESSOR_COMPONENT 0x01000000
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#define ACPI_PROCESSOR_CLASS "processor"
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#define _COMPONENT ACPI_PROCESSOR_COMPONENT
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ACPI_MODULE_NAME("processor_throttling");
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/* --------------------------------------------------------------------------
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Throttling Control
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-------------------------------------------------------------------------- */
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static int acpi_processor_get_throttling(struct acpi_processor *pr)
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{
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int state = 0;
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u32 value = 0;
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u32 duty_mask = 0;
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u32 duty_value = 0;
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if (!pr)
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return -EINVAL;
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if (!pr->flags.throttling)
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return -ENODEV;
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pr->throttling.state = 0;
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duty_mask = pr->throttling.state_count - 1;
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duty_mask <<= pr->throttling.duty_offset;
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local_irq_disable();
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value = inl(pr->throttling.address);
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/*
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* Compute the current throttling state when throttling is enabled
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* (bit 4 is on).
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*/
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if (value & 0x10) {
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duty_value = value & duty_mask;
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duty_value >>= pr->throttling.duty_offset;
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if (duty_value)
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state = pr->throttling.state_count - duty_value;
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}
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pr->throttling.state = state;
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local_irq_enable();
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ACPI_DEBUG_PRINT((ACPI_DB_INFO,
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"Throttling state is T%d (%d%% throttling applied)\n",
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state, pr->throttling.states[state].performance));
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return 0;
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}
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int acpi_processor_set_throttling(struct acpi_processor *pr, int state)
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{
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u32 value = 0;
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u32 duty_mask = 0;
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u32 duty_value = 0;
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if (!pr)
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return -EINVAL;
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if ((state < 0) || (state > (pr->throttling.state_count - 1)))
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return -EINVAL;
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if (!pr->flags.throttling)
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return -ENODEV;
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if (state == pr->throttling.state)
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return 0;
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/*
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* Calculate the duty_value and duty_mask.
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*/
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if (state) {
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duty_value = pr->throttling.state_count - state;
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duty_value <<= pr->throttling.duty_offset;
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/* Used to clear all duty_value bits */
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duty_mask = pr->throttling.state_count - 1;
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duty_mask <<= acpi_gbl_FADT.duty_offset;
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duty_mask = ~duty_mask;
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}
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local_irq_disable();
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/*
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* Disable throttling by writing a 0 to bit 4. Note that we must
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* turn it off before you can change the duty_value.
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*/
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value = inl(pr->throttling.address);
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if (value & 0x10) {
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value &= 0xFFFFFFEF;
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outl(value, pr->throttling.address);
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}
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/*
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* Write the new duty_value and then enable throttling. Note
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* that a state value of 0 leaves throttling disabled.
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*/
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if (state) {
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value &= duty_mask;
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value |= duty_value;
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outl(value, pr->throttling.address);
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value |= 0x00000010;
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outl(value, pr->throttling.address);
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}
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pr->throttling.state = state;
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local_irq_enable();
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ACPI_DEBUG_PRINT((ACPI_DB_INFO,
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"Throttling state set to T%d (%d%%)\n", state,
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(pr->throttling.states[state].performance ? pr->
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throttling.states[state].performance / 10 : 0)));
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return 0;
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}
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int acpi_processor_get_throttling_info(struct acpi_processor *pr)
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{
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int result = 0;
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int step = 0;
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int i = 0;
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ACPI_DEBUG_PRINT((ACPI_DB_INFO,
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"pblk_address[0x%08x] duty_offset[%d] duty_width[%d]\n",
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pr->throttling.address,
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pr->throttling.duty_offset,
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pr->throttling.duty_width));
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if (!pr)
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return -EINVAL;
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/* TBD: Support ACPI 2.0 objects */
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if (!pr->throttling.address) {
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ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n"));
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return 0;
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} else if (!pr->throttling.duty_width) {
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ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling states\n"));
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return 0;
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}
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/* TBD: Support duty_cycle values that span bit 4. */
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else if ((pr->throttling.duty_offset + pr->throttling.duty_width) > 4) {
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printk(KERN_WARNING PREFIX "duty_cycle spans bit 4\n");
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return 0;
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}
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/*
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* PIIX4 Errata: We don't support throttling on the original PIIX4.
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* This shouldn't be an issue as few (if any) mobile systems ever
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* used this part.
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*/
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if (errata.piix4.throttle) {
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ACPI_DEBUG_PRINT((ACPI_DB_INFO,
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"Throttling not supported on PIIX4 A- or B-step\n"));
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return 0;
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}
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pr->throttling.state_count = 1 << acpi_gbl_FADT.duty_width;
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/*
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* Compute state values. Note that throttling displays a linear power/
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* performance relationship (at 50% performance the CPU will consume
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* 50% power). Values are in 1/10th of a percent to preserve accuracy.
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*/
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step = (1000 / pr->throttling.state_count);
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for (i = 0; i < pr->throttling.state_count; i++) {
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pr->throttling.states[i].performance = step * i;
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pr->throttling.states[i].power = step * i;
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}
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ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d throttling states\n",
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pr->throttling.state_count));
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pr->flags.throttling = 1;
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/*
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* Disable throttling (if enabled). We'll let subsequent policy (e.g.
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* thermal) decide to lower performance if it so chooses, but for now
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* we'll crank up the speed.
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*/
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result = acpi_processor_get_throttling(pr);
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if (result)
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goto end;
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if (pr->throttling.state) {
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ACPI_DEBUG_PRINT((ACPI_DB_INFO,
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"Disabling throttling (was T%d)\n",
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pr->throttling.state));
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result = acpi_processor_set_throttling(pr, 0);
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if (result)
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goto end;
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}
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end:
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if (result)
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pr->flags.throttling = 0;
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return result;
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}
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/* proc interface */
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static int acpi_processor_throttling_seq_show(struct seq_file *seq,
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void *offset)
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{
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struct acpi_processor *pr = seq->private;
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int i = 0;
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int result = 0;
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if (!pr)
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goto end;
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if (!(pr->throttling.state_count > 0)) {
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seq_puts(seq, "<not supported>\n");
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goto end;
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}
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result = acpi_processor_get_throttling(pr);
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if (result) {
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seq_puts(seq,
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"Could not determine current throttling state.\n");
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goto end;
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}
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seq_printf(seq, "state count: %d\n"
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"active state: T%d\n",
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pr->throttling.state_count, pr->throttling.state);
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seq_puts(seq, "states:\n");
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for (i = 0; i < pr->throttling.state_count; i++)
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seq_printf(seq, " %cT%d: %02d%%\n",
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(i == pr->throttling.state ? '*' : ' '), i,
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(pr->throttling.states[i].performance ? pr->
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throttling.states[i].performance / 10 : 0));
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end:
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return 0;
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}
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static int acpi_processor_throttling_open_fs(struct inode *inode,
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struct file *file)
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{
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return single_open(file, acpi_processor_throttling_seq_show,
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PDE(inode)->data);
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}
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static ssize_t acpi_processor_write_throttling(struct file * file,
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const char __user * buffer,
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size_t count, loff_t * data)
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{
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int result = 0;
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struct seq_file *m = file->private_data;
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struct acpi_processor *pr = m->private;
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char state_string[12] = { '\0' };
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if (!pr || (count > sizeof(state_string) - 1))
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return -EINVAL;
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if (copy_from_user(state_string, buffer, count))
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return -EFAULT;
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state_string[count] = '\0';
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result = acpi_processor_set_throttling(pr,
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simple_strtoul(state_string,
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NULL, 0));
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if (result)
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return result;
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return count;
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}
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struct file_operations acpi_processor_throttling_fops = {
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.open = acpi_processor_throttling_open_fs,
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.read = seq_read,
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.write = acpi_processor_write_throttling,
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.llseek = seq_lseek,
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.release = single_release,
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};
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