text: /*
   * processor_thermal.c - Passive cooling 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 <asm/uaccess.h>
  
  #include <acpi/acpi_bus.h>
  #include <acpi/processor.h>
  #include <acpi/acpi_drivers.h>
  
  #define PREFIX "ACPI: "
  
  #define ACPI_PROCESSOR_CLASS            "processor"
  #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
  ACPI_MODULE_NAME("processor_thermal");
  
  #ifdef CONFIG_CPU_FREQ
  
  /* If a passive cooling situation is detected, primarily CPUfreq is used, as it
   * offers (in most cases) voltage scaling in addition to frequency scaling, and
   * thus a cubic (instead of linear) reduction of energy. Also, we allow for
   * _any_ cpufreq driver and not only the acpi-cpufreq driver.
   */
  
  #define CPUFREQ_THERMAL_MIN_STEP 0
  #define CPUFREQ_THERMAL_MAX_STEP 3
  
  static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
  static unsigned int acpi_thermal_cpufreq_is_init = 0;
  
  #define reduction_pctg(cpu) \
  	per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))
  
  /*
   * Emulate "per package data" using per cpu data (which should really be
   * provided elsewhere)
   *
   * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
   * temporarily. Fortunately that's not a big issue here (I hope)
   */
  static int phys_package_first_cpu(int cpu)
  {
  	int i;
  	int id = topology_physical_package_id(cpu);
  
  	for_each_online_cpu(i)
  		if (topology_physical_package_id(i) == id)
  			return i;
  	return 0;
  }
  
  static int cpu_has_cpufreq(unsigned int cpu)
  {
  	struct cpufreq_policy policy;
  	if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
  		return 0;
  	return 1;
  }
  
  static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
  					 unsigned long event, void *data)
  {
  	struct cpufreq_policy *policy = data;
  	unsigned long max_freq = 0;
  
  	if (event != CPUFREQ_ADJUST)
  		goto out;
  
  	max_freq = (
  	    policy->cpuinfo.max_freq *
  	    (100 - reduction_pctg(policy->cpu) * 20)
  	) / 100;
  
  	cpufreq_verify_within_limits(policy, 0, max_freq);
  
        out:
  	return 0;
  }
  
  static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
  	.notifier_call = acpi_thermal_cpufreq_notifier,
  };
  
  static int cpufreq_get_max_state(unsigned int cpu)
  {
  	if (!cpu_has_cpufreq(cpu))
  		return 0;
  
  	return CPUFREQ_THERMAL_MAX_STEP;
  }
  
  static int cpufreq_get_cur_state(unsigned int cpu)
  {
  	if (!cpu_has_cpufreq(cpu))
  		return 0;
  
  	return reduction_pctg(cpu);
  }
  
  static int cpufreq_set_cur_state(unsigned int cpu, int state)
  {
  	int i;
  
  	if (!cpu_has_cpufreq(cpu))
  		return 0;
  
  	reduction_pctg(cpu) = state;
  
  	/*
  	 * Update all the CPUs in the same package because they all
  	 * contribute to the temperature and often share the same
  	 * frequency.
  	 */
  	for_each_online_cpu(i) {
  		if (topology_physical_package_id(i) ==
  		    topology_physical_package_id(cpu))
  			cpufreq_update_policy(i);
  	}
  	return 0;
  }
  
  void acpi_thermal_cpufreq_init(void)
  {
  	int i;
  
  	i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
  				      CPUFREQ_POLICY_NOTIFIER);
  	if (!i)
  		acpi_thermal_cpufreq_is_init = 1;
  }
  
  void acpi_thermal_cpufreq_exit(void)
  {
  	if (acpi_thermal_cpufreq_is_init)
  		cpufreq_unregister_notifier
  		    (&acpi_thermal_cpufreq_notifier_block,
  		     CPUFREQ_POLICY_NOTIFIER);
  
  	acpi_thermal_cpufreq_is_init = 0;
  }
  
  #else				/* ! CONFIG_CPU_FREQ */
  static int cpufreq_get_max_state(unsigned int cpu)
  {
  	return 0;
  }
  
  static int cpufreq_get_cur_state(unsigned int cpu)
  {
  	return 0;
  }
  
  static int cpufreq_set_cur_state(unsigned int cpu, int state)
  {
  	return 0;
  }
  
  #endif
  
  /* thermal coolign device callbacks */
  static int acpi_processor_max_state(struct acpi_processor *pr)
  {
  	int max_state = 0;
  
  	/*
  	 * There exists four states according to
  	 * cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
  	 */
  	max_state += cpufreq_get_max_state(pr->id);
  	if (pr->flags.throttling)
  		max_state += (pr->throttling.state_count -1);
  
  	return max_state;
  }
  static int
  processor_get_max_state(struct thermal_cooling_device *cdev,
  			unsigned long *state)
  {
  	struct acpi_device *device = cdev->devdata;
  	struct acpi_processor *pr;
  
  	if (!device)
  		return -EINVAL;
  
  	pr = acpi_driver_data(device);
  	if (!pr)
  		return -EINVAL;
  
  	*state = acpi_processor_max_state(pr);
  	return 0;
  }
  
  static int
  processor_get_cur_state(struct thermal_cooling_device *cdev,
  			unsigned long *cur_state)
  {
  	struct acpi_device *device = cdev->devdata;
  	struct acpi_processor *pr;
  
  	if (!device)
  		return -EINVAL;
  
  	pr = acpi_driver_data(device);
  	if (!pr)
  		return -EINVAL;
  
  	*cur_state = cpufreq_get_cur_state(pr->id);
  	if (pr->flags.throttling)
  		*cur_state += pr->throttling.state;
  	return 0;
  }
  
  static int
  processor_set_cur_state(struct thermal_cooling_device *cdev,
  			unsigned long state)
  {
  	struct acpi_device *device = cdev->devdata;
  	struct acpi_processor *pr;
  	int result = 0;
  	int max_pstate;
  
  	if (!device)
  		return -EINVAL;
  
  	pr = acpi_driver_data(device);
  	if (!pr)
  		return -EINVAL;
  
  	max_pstate = cpufreq_get_max_state(pr->id);
  
  	if (state > acpi_processor_max_state(pr))
  		return -EINVAL;
  
  	if (state <= max_pstate) {
  		if (pr->flags.throttling && pr->throttling.state)
  			result = acpi_processor_set_throttling(pr, 0, false);
  		cpufreq_set_cur_state(pr->id, state);
  	} else {
  		cpufreq_set_cur_state(pr->id, max_pstate);
  		result = acpi_processor_set_throttling(pr,
  				state - max_pstate, false);
  	}
  	return result;
  }
  
  const struct thermal_cooling_device_ops processor_cooling_ops = {
  	.get_max_state = processor_get_max_state,
  	.get_cur_state = processor_get_cur_state,
  	.set_cur_state = processor_set_cur_state,
  };
  