[V2,2/6] thermal: Add generic cpufreq cooling implementation

diff --git a/Documentation/thermal/cpu-cooling-api.txt b/Documentation/thermal/cpu-cooling-api.txt
new file mode 100644
index 0000000..3720341
--- /dev/null
+++ b/Documentation/thermal/cpu-cooling-api.txt
@@ -0,0 +1,60 @@ 
+CPU cooling APIs How To
+===================================
+
+Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
+
+Updated: 9 March 2012
+
+Copyright (c)  2011 Samsung Electronics Co., Ltd(http://www.samsung.com)
+
+0. Introduction
+
+The generic cpu cooling(freq clipping, cpuhotplug) provides
+registration/unregistration APIs to the caller. The binding of the cooling
+devices to the trip point is left for the user. The registration APIs returns
+the cooling device pointer.
+
+1. cpu cooling APIs
+
+1.1 cpufreq registration/unregistration APIs
+1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
+	struct freq_clip_table *tab_ptr, unsigned int tab_size,
+	const struct cpumask *mask_val)
+
+    This interface function registers the cpufreq cooling device with the name
+    "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
+    cooling devices.
+
+    tab_ptr: The table containing the maximum value of frequency to be clipped
+    for each cooling state.
+	.freq_clip_max: Value of frequency to be clipped for each allowed
+	 cpus.
+    tab_size: the total number of cpufreq cooling states.
+    mask_val: all the allowed cpu's where frequency clipping can happen.
+
+1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
+
+    This interface function unregisters the "thermal-cpufreq-%x" cooling device.
+
+    cdev: Cooling device pointer which has to be unregistered.
+
+
+2. CPU cooling action notifier interface
+
+2.1 int cputherm_register_notifier(struct notifier_block *nb,
+	unsigned int list)
+
+    This interface registers a driver with cpu cooling layer. The driver will
+    be notified when any cpu cooling action is called.
+
+    nb: notifier function to register
+    list: CPUFREQ_COOLING_TYPE or CPUHOTPLUG_COOLING_TYPE
+
+2.2 int cputherm_unregister_notifier(struct notifier_block *nb,
+	unsigned int list)
+
+    This interface registers a driver with cpu cooling layer. The driver will
+    be notified when any cpu cooling action is called.
+
+    nb: notifier function to register
+    list: CPUFREQ_COOLING_TYPE or CPUHOTPLUG_COOLING_TYPE
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index f7f71b2..df738f2 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -18,3 +18,14 @@  config THERMAL_HWMON
 	depends on THERMAL
 	depends on HWMON=y || HWMON=THERMAL
 	default y
+
+config CPU_THERMAL
+	bool "generic cpu cooling support"
+	depends on THERMAL && CPU_FREQ
+	help
+	  This implements the generic cpu cooling mechanism through frequency
+	  reduction, cpu hotplug and any other ways of reducing temperature. An
+	  ACPI version of this already exists(drivers/acpi/processor_thermal.c).
+	  This will be useful for platforms using the generic thermal interface
+	  and not the ACPI interface.
+	  If you want this support, you should say Y or M here.
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 31108a0..655cbc4 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -3,3 +3,4 @@ 
 #
 
 obj-$(CONFIG_THERMAL)		+= thermal_sys.o
+obj-$(CONFIG_CPU_THERMAL)	+= cpu_cooling.o
diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
new file mode 100644
index 0000000..ee2c96d
--- /dev/null
+++ b/drivers/thermal/cpu_cooling.c
@@ -0,0 +1,359 @@ 
+/*
+ *  linux/drivers/thermal/cpu_cooling.c
+ *
+ *  Copyright (C) 2011	Samsung Electronics Co., Ltd(http://www.samsung.com)
+ *  Copyright (C) 2011  Amit Daniel <amit.kachhap@linaro.org>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *  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; version 2 of the License.
+ *
+ *  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/thermal.h>
+#include <linux/platform_device.h>
+#include <linux/cpufreq.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/cpu.h>
+#include <linux/cpu_cooling.h>
+
+struct cpufreq_cooling_device {
+	int id;
+	struct thermal_cooling_device *cool_dev;
+	struct freq_clip_table *tab_ptr;
+	unsigned int tab_size;
+	unsigned int cpufreq_state;
+	const struct cpumask *allowed_cpus;
+	struct list_head node;
+};
+
+static LIST_HEAD(cooling_cpufreq_list);
+static DEFINE_MUTEX(cooling_cpufreq_lock);
+static DEFINE_IDR(cpufreq_idr);
+static DEFINE_PER_CPU(unsigned int, max_policy_freq);
+static struct freq_clip_table *notify_table;
+static int notify_state;
+static BLOCKING_NOTIFIER_HEAD(cputherm_state_notifier_list);
+
+static int get_idr(struct idr *idr, struct mutex *lock, int *id)
+{
+	int err;
+again:
+	if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
+		return -ENOMEM;
+
+	if (lock)
+		mutex_lock(lock);
+	err = idr_get_new(idr, NULL, id);
+	if (lock)
+		mutex_unlock(lock);
+	if (unlikely(err == -EAGAIN))
+		goto again;
+	else if (unlikely(err))
+		return err;
+
+	*id = *id & MAX_ID_MASK;
+	return 0;
+}
+
+static void release_idr(struct idr *idr, struct mutex *lock, int id)
+{
+	if (lock)
+		mutex_lock(lock);
+	idr_remove(idr, id);
+	if (lock)
+		mutex_unlock(lock);
+}
+
+int cputherm_register_notifier(struct notifier_block *nb, unsigned int list)
+{
+	int ret = 0;
+
+	switch (list) {
+	case CPUFREQ_COOLING_TYPE:
+	case CPUHOTPLUG_COOLING_TYPE:
+		ret = blocking_notifier_chain_register(
+				&cputherm_state_notifier_list, nb);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	return ret;
+}
+EXPORT_SYMBOL(cputherm_register_notifier);
+
+int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int list)
+{
+	int ret = 0;
+
+	switch (list) {
+	case CPUFREQ_COOLING_TYPE:
+	case CPUHOTPLUG_COOLING_TYPE:
+		ret = blocking_notifier_chain_unregister(
+				&cputherm_state_notifier_list, nb);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	return ret;
+}
+EXPORT_SYMBOL(cputherm_unregister_notifier);
+
+/*Below codes defines functions to be used for cpufreq as cooling device*/
+static bool is_cpufreq_valid(int cpu)
+{
+	struct cpufreq_policy policy;
+	return !cpufreq_get_policy(&policy, cpu) ? true : false;
+}
+
+static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
+				unsigned long cooling_state)
+{
+	unsigned int event, cpuid;
+	struct freq_clip_table *th_table;
+
+	if (cooling_state > cpufreq_device->tab_size)
+		return -EINVAL;
+
+	cpufreq_device->cpufreq_state = cooling_state;
+
+	/*cpufreq thermal notifier uses this cpufreq device pointer*/
+	notify_state = cooling_state;
+
+	if (notify_state > 0) {
+		th_table = &(cpufreq_device->tab_ptr[cooling_state - 1]);
+		memcpy(notify_table, th_table, sizeof(struct freq_clip_table));
+		event = CPUFREQ_COOLING_TYPE;
+		blocking_notifier_call_chain(&cputherm_state_notifier_list,
+						event, notify_table);
+	}
+
+	for_each_cpu(cpuid, cpufreq_device->allowed_cpus) {
+		if (is_cpufreq_valid(cpuid))
+			cpufreq_update_policy(cpuid);
+	}
+
+	notify_state = -1;
+
+	return 0;
+}
+
+static int cpufreq_thermal_notifier(struct notifier_block *nb,
+					unsigned long event, void *data)
+{
+	struct cpufreq_policy *policy = data;
+	unsigned long max_freq = 0;
+
+	if ((event != CPUFREQ_ADJUST) || (notify_state == -1))
+		return 0;
+
+	if (notify_state > 0) {
+		max_freq = notify_table->freq_clip_max;
+
+		if (per_cpu(max_policy_freq, policy->cpu) == 0)
+			per_cpu(max_policy_freq, policy->cpu) = policy->max;
+	} else {
+		if (per_cpu(max_policy_freq, policy->cpu) != 0) {
+			max_freq = per_cpu(max_policy_freq, policy->cpu);
+			per_cpu(max_policy_freq, policy->cpu) = 0;
+		} else {
+			max_freq = policy->max;
+		}
+	}
+
+	/* Never exceed user_policy.max*/
+	if (max_freq > policy->user_policy.max)
+		max_freq = policy->user_policy.max;
+
+	if (policy->max != max_freq)
+		cpufreq_verify_within_limits(policy, 0, max_freq);
+
+	return 0;
+}
+
+/*
+ * cpufreq cooling device callback functions
+ */
+static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
+				 unsigned long *state)
+{
+	int ret = -EINVAL;
+	struct cpufreq_cooling_device *cpufreq_device;
+
+	mutex_lock(&cooling_cpufreq_lock);
+	list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
+		if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
+			*state = cpufreq_device->tab_size;
+			ret = 0;
+			break;
+		}
+	}
+	mutex_unlock(&cooling_cpufreq_lock);
+	return ret;
+}
+
+static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
+				 unsigned long *state)
+{
+	int ret = -EINVAL;
+	struct cpufreq_cooling_device *cpufreq_device;
+
+	mutex_lock(&cooling_cpufreq_lock);
+	list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
+		if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
+			*state = cpufreq_device->cpufreq_state;
+			ret = 0;
+			break;
+		}
+	}
+	mutex_unlock(&cooling_cpufreq_lock);
+	return ret;
+}
+
+/*This cooling may be as PASSIVE/ACTIVE type*/
+static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
+				 unsigned long state)
+{
+	int ret = -EINVAL;
+	struct cpufreq_cooling_device *cpufreq_device;
+
+	mutex_lock(&cooling_cpufreq_lock);
+	list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
+		if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
+			ret = 0;
+			break;
+		}
+	}
+	mutex_unlock(&cooling_cpufreq_lock);
+
+	if (!ret)
+		ret = cpufreq_apply_cooling(cpufreq_device, state);
+
+	return ret;
+}
+
+/* bind cpufreq callbacks to cpufreq cooling device */
+static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
+	.get_max_state = cpufreq_get_max_state,
+	.get_cur_state = cpufreq_get_cur_state,
+	.set_cur_state = cpufreq_set_cur_state,
+};
+
+static struct notifier_block thermal_cpufreq_notifier_block = {
+	.notifier_call = cpufreq_thermal_notifier,
+};
+
+struct thermal_cooling_device *cpufreq_cooling_register(
+	struct freq_clip_table *tab_ptr, unsigned int tab_size,
+	const struct cpumask *mask_val)
+{
+	struct thermal_cooling_device *cool_dev;
+	struct cpufreq_cooling_device *cpufreq_dev = NULL;
+	unsigned int cpufreq_dev_count = 0;
+	char dev_name[THERMAL_NAME_LENGTH];
+	int ret = 0, id = 0, i;
+
+	if (tab_ptr == NULL || tab_size == 0)
+		return ERR_PTR(-EINVAL);
+
+	list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
+		cpufreq_dev_count++;
+
+	cpufreq_dev =
+		kzalloc(sizeof(struct cpufreq_cooling_device), GFP_KERNEL);
+
+	if (!cpufreq_dev)
+		return ERR_PTR(-ENOMEM);
+
+	if (cpufreq_dev_count == 0) {
+		notify_table = kzalloc(sizeof(struct freq_clip_table),
+					GFP_KERNEL);
+		if (!notify_table) {
+			kfree(cpufreq_dev);
+			return ERR_PTR(-ENOMEM);
+		}
+	}
+
+	cpufreq_dev->tab_ptr = tab_ptr;
+	cpufreq_dev->tab_size = tab_size;
+	cpufreq_dev->allowed_cpus = mask_val;
+
+	/* Initialize all the tab_ptr->mask_val to the passed mask_val */
+	for (i = 0; i < tab_size; i++)
+		((struct freq_clip_table *)&tab_ptr[i])->mask_val = mask_val;
+
+	ret = get_idr(&cpufreq_idr, &cooling_cpufreq_lock, &cpufreq_dev->id);
+	if (ret) {
+		kfree(cpufreq_dev);
+		return ERR_PTR(-EINVAL);
+	}
+
+	sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
+
+	cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
+						&cpufreq_cooling_ops);
+	if (!cool_dev) {
+		release_idr(&cpufreq_idr, &cooling_cpufreq_lock,
+						cpufreq_dev->id);
+		kfree(cpufreq_dev);
+		return ERR_PTR(-EINVAL);
+	}
+	cpufreq_dev->id = id;
+	cpufreq_dev->cool_dev = cool_dev;
+	mutex_lock(&cooling_cpufreq_lock);
+	list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
+	mutex_unlock(&cooling_cpufreq_lock);
+
+	/*Register the notifier for first cpufreq cooling device*/
+	if (cpufreq_dev_count == 0)
+		cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
+						CPUFREQ_POLICY_NOTIFIER);
+	return cool_dev;
+}
+EXPORT_SYMBOL(cpufreq_cooling_register);
+
+void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
+{
+	struct cpufreq_cooling_device *cpufreq_dev = NULL;
+	unsigned int cpufreq_dev_count = 0;
+
+	mutex_lock(&cooling_cpufreq_lock);
+	list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node) {
+		if (cpufreq_dev && cpufreq_dev->cool_dev == cdev)
+			break;
+		cpufreq_dev_count++;
+	}
+
+	if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
+		mutex_unlock(&cooling_cpufreq_lock);
+		return;
+	}
+
+	list_del(&cpufreq_dev->node);
+	mutex_unlock(&cooling_cpufreq_lock);
+
+	/*Unregister the notifier for the last cpufreq cooling device*/
+	if (cpufreq_dev_count == 1) {
+		cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
+					CPUFREQ_POLICY_NOTIFIER);
+		kfree(notify_table);
+	}
+
+	thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
+	release_idr(&cpufreq_idr, &cooling_cpufreq_lock, cpufreq_dev->id);
+	kfree(cpufreq_dev);
+}
+EXPORT_SYMBOL(cpufreq_cooling_unregister);
diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
new file mode 100644
index 0000000..12efa01
--- /dev/null
+++ b/include/linux/cpu_cooling.h
@@ -0,0 +1,61 @@ 
+/*
+ *  linux/include/linux/cpu_cooling.h
+ *
+ *  Copyright (C) 2011	Samsung Electronics Co., Ltd(http://www.samsung.com)
+ *  Copyright (C) 2011  Amit Daniel <amit.kachhap@linaro.org>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *  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; version 2 of the License.
+ *
+ *  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.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#ifndef __CPU_COOLING_H__
+#define __CPU_COOLING_H__
+
+#include <linux/thermal.h>
+
+#define CPUFREQ_COOLING_TYPE		0
+#define CPUHOTPLUG_COOLING_TYPE		1
+
+struct freq_clip_table {
+	unsigned int freq_clip_max;
+	unsigned int temp_level;
+	const struct cpumask *mask_val;
+};
+
+int cputherm_register_notifier(struct notifier_block *nb, unsigned int list);
+int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int list);
+
+#ifdef CONFIG_CPU_FREQ
+struct thermal_cooling_device *cpufreq_cooling_register(
+	struct freq_clip_table *tab_ptr, unsigned int tab_size,
+	const struct cpumask *mask_val);
+
+void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
+#else /*!CONFIG_CPU_FREQ*/
+static inline struct thermal_cooling_device *cpufreq_cooling_register(
+	struct freq_clip_table *tab_ptr, unsigned int tab_size,
+	const struct cpumask *mask_val)
+{
+	return NULL;
+}
+static inline void cpufreq_cooling_unregister(
+				struct thermal_cooling_device *cdev)
+{
+	return;
+}
+#endif	/*CONFIG_CPU_FREQ*/
+
+#endif /* __CPU_COOLING_H__ */