drivers/acpi/processor_throttling.c - maze/linux - Git at Google

 /*
  * 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("processor_throttling");

 /* --------------------------------------------------------------------------
                               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;


 	if (!pr)
 		return -EINVAL;

 	if (!pr->flags.throttling)
 		return -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 0;
 }

 int acpi_processor_set_throttling(struct acpi_processor *pr, int state)
 {
 	u32 value = 0;
 	u32 duty_mask = 0;
 	u32 duty_value = 0;


 	if (!pr)
 		return -EINVAL;

 	if ((state < 0) || (state > (pr->throttling.state_count - 1)))
 		return -EINVAL;

 	if (!pr->flags.throttling)
 		return -ENODEV;

 	if (state == pr->throttling.state)
 		return 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_gbl_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 0;
 }

 int acpi_processor_get_throttling_info(struct acpi_processor *pr)
 {
 	int result = 0;
 	int step = 0;
 	int i = 0;


 	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 -EINVAL;

 	/* TBD: Support ACPI 2.0 objects */

 	if (!pr->throttling.address) {
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n"));
 		return 0;
 	} else if (!pr->throttling.duty_width) {
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling states\n"));
 		return 0;
 	}
 	/* TBD: Support duty_cycle values that span bit 4. */
 	else if ((pr->throttling.duty_offset + pr->throttling.duty_width) > 4) {
 		printk(KERN_WARNING PREFIX "duty_cycle spans bit 4\n");
 		return 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 0;
 	}

 	pr->throttling.state_count = 1 << acpi_gbl_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 result;
 }

 /* proc interface */

 static int acpi_processor_throttling_seq_show(struct seq_file *seq,
 					      void *offset)
 {
 	struct acpi_processor *pr = seq->private;
 	int i = 0;
 	int result = 0;


 	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 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);
 }

 static 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 = file->private_data;
 	struct acpi_processor *pr = m->private;
 	char state_string[12] = { '\0' };


 	if (!pr || (count > sizeof(state_string) - 1))
 		return -EINVAL;

 	if (copy_from_user(state_string, buffer, count))
 		return -EFAULT;

 	state_string[count] = '\0';

 	result = acpi_processor_set_throttling(pr,
 					       simple_strtoul(state_string,
 							      NULL, 0));
 	if (result)
 		return result;

 	return count;
 }

 struct file_operations acpi_processor_throttling_fops = {
 	.open = acpi_processor_throttling_open_fs,
 	.read = seq_read,
 	.write = acpi_processor_write_throttling,
 	.llseek = seq_lseek,
 	.release = single_release,
 };
	/*
	* 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("processor_throttling");

	/* --------------------------------------------------------------------------
	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;


	if (!pr)
	return -EINVAL;

	if (!pr->flags.throttling)
	return -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 0;
	}

	int acpi_processor_set_throttling(struct acpi_processor *pr, int state)
	{
	u32 value = 0;
	u32 duty_mask = 0;
	u32 duty_value = 0;


	if (!pr)
	return -EINVAL;

	if ((state < 0) \|\| (state > (pr->throttling.state_count - 1)))
	return -EINVAL;

	if (!pr->flags.throttling)
	return -ENODEV;

	if (state == pr->throttling.state)
	return 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_gbl_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 0;
	}

	int acpi_processor_get_throttling_info(struct acpi_processor *pr)
	{
	int result = 0;
	int step = 0;
	int i = 0;


	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 -EINVAL;

	/* TBD: Support ACPI 2.0 objects */

	if (!pr->throttling.address) {
	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n"));
	return 0;
	} else if (!pr->throttling.duty_width) {
	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling states\n"));
	return 0;
	}
	/* TBD: Support duty_cycle values that span bit 4. */
	else if ((pr->throttling.duty_offset + pr->throttling.duty_width) > 4) {
	printk(KERN_WARNING PREFIX "duty_cycle spans bit 4\n");
	return 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 0;
	}

	pr->throttling.state_count = 1 << acpi_gbl_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 result;
	}

	/* proc interface */

	static int acpi_processor_throttling_seq_show(struct seq_file *seq,
	void *offset)
	{
	struct acpi_processor *pr = seq->private;
	int i = 0;
	int result = 0;


	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 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);
	}

	static 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 = file->private_data;
	struct acpi_processor *pr = m->private;
	char state_string[12] = { '\0' };


	if (!pr \|\| (count > sizeof(state_string) - 1))
	return -EINVAL;

	if (copy_from_user(state_string, buffer, count))
	return -EFAULT;

	state_string[count] = '\0';

	result = acpi_processor_set_throttling(pr,
	simple_strtoul(state_string,
	NULL, 0));
	if (result)
	return result;

	return count;
	}

	struct file_operations acpi_processor_throttling_fops = {
	.open = acpi_processor_throttling_open_fs,
	.read = seq_read,
	.write = acpi_processor_write_throttling,
	.llseek = seq_lseek,
	.release = single_release,
	};