[v2,2/2] thermal: devfreq_cooling: Add generic devfreq cooling device implementaion

diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt
index 8a49362dea6e..4201fb606cb2 100644
--- a/Documentation/devicetree/bindings/thermal/thermal.txt
+++ b/Documentation/devicetree/bindings/thermal/thermal.txt
@@ -43,10 +43,10 @@  Required property:
 Cooling devices are nodes providing control on power dissipation. There
 are essentially two ways to provide control on power dissipation. First
 is by means of regulating device performance, which is known as passive
-cooling. A typical passive cooling is a CPU that has dynamic voltage and
-frequency scaling (DVFS), and uses lower frequencies as cooling states.
-Second is by means of activating devices in order to remove
-the dissipated heat, which is known as active cooling, e.g. regulating
+cooling. A typical passive cooling is a CPU and Devfreq device that has
+dynamic voltage and frequency scaling (DVFS), and uses lower frequencies
+as cooling states. Second is by means of activating devices in order to
+remove the dissipated heat, which is known as active cooling, e.g. regulating
 fan speeds. In both cases, cooling devices shall have a way to determine
 the state of cooling in which the device is.
 
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 118938ee8552..764502d83de7 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -137,6 +137,17 @@  config CPU_THERMAL
 
 	  If you want this support, you should say Y here.
 
+config DEVFREQ_THERMAL
+	bool "generic devfreq cooling support"
+	depends on PM_DEVFREQ
+	depends on THERMAL_OF
+	help
+	  This implements the generic devfreq cooling mechanism through frequency
+	  reduction. This will be useful for platforms using the generic thermal
+	  interface.
+
+	  If you want this support, you should say Y here.
+
 config CLOCK_THERMAL
 	bool "Generic clock cooling support"
 	depends on COMMON_CLK
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 535dfee1496f..c5ca0cc3ff95 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -19,6 +19,9 @@  thermal_sys-$(CONFIG_THERMAL_GOV_POWER_ALLOCATOR)	+= power_allocator.o
 # cpufreq cooling
 thermal_sys-$(CONFIG_CPU_THERMAL)	+= cpu_cooling.o
 
+# devfreq cooling
+thermal_sys-$(CONFIG_DEVFREQ_THERMAL)	+= devfreq-cooling.o
+
 # clock cooling
 thermal_sys-$(CONFIG_CLOCK_THERMAL)	+= clock_cooling.o
 
diff --git a/drivers/thermal/devfreq-cooling.c b/drivers/thermal/devfreq-cooling.c
new file mode 100644
index 000000000000..5eb30bc3129b
--- /dev/null
+++ b/drivers/thermal/devfreq-cooling.c
@@ -0,0 +1,310 @@ 
+/*
+ *  linux/drivers/thermal/devfreq-cooling.c
+ *
+ *  Copyright (C) 2015 Samsung Electronics Co., Ltd
+ *  Author: Chanwoo Choi <cw00.choi@samsung.com>
+ *
+ *  This driver is based on drivers/thermal/cpu_cooling.c.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *  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/module.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/thermal.h>
+#include <linux/devfreq.h>
+#include <linux/devfreq-cooling.h>
+
+/*
+ * Cooling state <-> devfreq frequency
+ *
+ * Cooling states are translated to frequencies throughout this driver and this
+ * is the relation between them.
+ *
+ * Highest cooling state corresponds to lowest possible frequency.
+ *
+ * i.e.
+ *	level 0 --> 1st Max Freq
+ *	level 1 --> 2nd Max Freq
+ *	...
+ */
+
+/**
+ * struct devfreq_cooling_device - data for cooling device with devfreq
+ * @cool_dev:	thermal_cooling_device pointer to keep track of the
+ *		registered cooling device.
+ * @devfreq:	the devfreq instance.
+ * @cur_state:	integer value representing the current state of devfreq
+ *		cooling	devices.
+ * @max_state:	interger value representing the maximum state of devfreq
+ *		cooling devices.
+ *
+ * This structure is required for keeping information of each registered
+ * devfreq_cooling_device.
+ */
+struct devfreq_cooling_device {
+	struct thermal_cooling_device *cool_dev;
+	struct devfreq *devfreq;
+
+	unsigned int cur_state;
+	unsigned int max_state;
+
+	unsigned int *freq_table;	/* In descending order */
+};
+
+/* devfreq cooling device callback functions are defined below */
+
+/**
+ * devfreq_get_max_state - callback function to get the max cooling state.
+ * @cdev:	thermal cooling device pointer.
+ * @state:	fill this variable with the max cooling state.
+ *
+ * Callback for the thermal cooling device to return the devfreq
+ * max cooling state.
+ *
+ * Return: 0 on success, an error code otherwise.
+ */
+static int devfreq_get_max_state(struct thermal_cooling_device *cdev,
+				 unsigned long *state)
+{
+	struct devfreq_cooling_device *devfreq_device = cdev->devdata;
+
+	*state = devfreq_device->max_state;
+
+	return 0;
+}
+
+/**
+ * devfreq_get_cur_state - callback function to get the current cooling state.
+ * @cdev:	thermal cooling device pointer.
+ * @state:	fill this variable with the current cooling state.
+ *
+ * Callback for the thermal cooling device to return the devfreq
+ * current cooling state.
+ *
+ * Return: 0 on success, an error code otherwise.
+ */
+static int devfreq_get_cur_state(struct thermal_cooling_device *cdev,
+				 unsigned long *state)
+{
+	struct devfreq_cooling_device *devfreq_device = cdev->devdata;
+
+	*state = devfreq_device->cur_state;
+
+	return 0;
+}
+
+/**
+ * devfreq_set_cur_state - callback function to set the current cooling state.
+ * @cdev:	thermal cooling device pointer.
+ * @state:	set this variable to the current cooling state.
+ *
+ * Callback for the thermal cooling device to change the devfreq
+ * current cooling state.
+ *
+ * Return: 0 on success, an error code otherwise.
+ */
+static int devfreq_set_cur_state(struct thermal_cooling_device *cdev,
+				 unsigned long state)
+{
+	struct devfreq_cooling_device *devfreq_dev = cdev->devdata;
+	unsigned int limited_freq;
+
+	/* Request state should be less than max_level */
+	if (WARN_ON(state > devfreq_dev->max_state))
+		return -EINVAL;
+
+	/* Check if the old cooling action is same as new cooling action */
+	if (devfreq_dev->cur_state == state)
+		return 0;
+
+	limited_freq = devfreq_dev->freq_table[state];
+
+	devfreq_dev->cur_state = state;
+
+	/* Set the limited frequency to maximum frequency of devfreq */
+	devfreq_dev->devfreq->max_freq = limited_freq;
+	update_devfreq(devfreq_dev->devfreq);
+
+	return 0;
+}
+
+/* Bind devfreq callbacks to thermal cooling device ops */
+static struct thermal_cooling_device_ops const devfreq_cooling_ops = {
+	.get_max_state = devfreq_get_max_state,
+	.get_cur_state = devfreq_get_cur_state,
+	.set_cur_state = devfreq_set_cur_state,
+};
+
+/**
+ * __devfreq_cooling_register - helper function to create devfreq cooling device
+ * @np:		a valid struct device_node to the cooling device tree node
+ * @devfreq:	the devfreq instance.
+ *
+ * This interface function registers the devfreq cooling device with the name
+ * "thermal-devfreq-%x". This api can support multiple instances of devfreq
+ * cooling devices. It also gives the opportunity to link the cooling device
+ * with a device tree node, in order to bind it via the thermal DT code.
+ *
+ * Return: a valid struct thermal_cooling_device pointer on success,
+ * on failure, it returns a corresponding ERR_PTR().
+ */
+static struct thermal_cooling_device *
+__devfreq_cooling_register(struct device_node *np, struct devfreq *devfreq)
+{
+	struct thermal_cooling_device *cool_dev;
+	struct devfreq_cooling_device *devfreq_dev;
+	struct devfreq_dev_profile *devfreq_profile = devfreq->profile;
+	struct dev_pm_opp *opp;
+	static atomic_t devfreq_cooling_no = ATOMIC_INIT(-1);
+	char dev_name[THERMAL_NAME_LENGTH];
+	unsigned long freq;
+	int i;
+
+	devfreq_dev = kzalloc(sizeof(*devfreq_dev), GFP_KERNEL);
+	if (!devfreq_dev)
+		return ERR_PTR(-ENOMEM);
+
+	rcu_read_lock();
+	devfreq_dev->max_state = dev_pm_opp_get_opp_count(devfreq->dev.parent);
+	if (devfreq_dev->max_state <= 0) {
+		rcu_read_unlock();
+		cool_dev = ERR_PTR(-EINVAL);
+		goto free_cdev;
+	}
+	devfreq_dev->max_state -= 1;
+	rcu_read_unlock();
+
+	/*
+	 * Use the freq_table of devfreq_dev_profile structure
+	 * if the devfreq_dev_profile includes already filled frequency table.
+	 */
+	if (devfreq_profile->freq_table) {
+		devfreq_dev->freq_table = devfreq_profile->freq_table;
+		goto register_cooling_dev;
+	}
+
+	/* Allocate the frequency table and fill it */
+	rcu_read_lock();
+	devfreq_dev->freq_table = kzalloc(sizeof(*devfreq_dev->freq_table) *
+					devfreq_dev->max_state, GFP_KERNEL);
+	if (!devfreq_dev->freq_table) {
+		rcu_read_unlock();
+		cool_dev = ERR_PTR(-ENOMEM);
+		goto free_cdev;
+	}
+
+	freq = ULONG_MAX;
+	for (i = 0; i <= devfreq_dev->max_state; i++, freq--) {
+		opp = dev_pm_opp_find_freq_floor(devfreq->dev.parent,
+						&freq);
+		if (IS_ERR(opp)) {
+			rcu_read_unlock();
+			cool_dev = ERR_PTR(-EINVAL);
+			goto free_table;
+		}
+		devfreq_dev->freq_table[i] = freq;
+	}
+	rcu_read_unlock();
+
+register_cooling_dev:
+	/* Register cooling device with devfreq device */
+	snprintf(dev_name, sizeof(dev_name), "thermal-devfreq-%d",
+			atomic_inc_return(&devfreq_cooling_no));
+
+	cool_dev = thermal_of_cooling_device_register(np, dev_name, devfreq_dev,
+						      &devfreq_cooling_ops);
+	if (IS_ERR(cool_dev))
+		goto free_table;
+
+	devfreq_dev->devfreq = devfreq;
+	devfreq_dev->cool_dev = cool_dev;
+
+	return cool_dev;
+
+free_table:
+	kfree(devfreq_dev->freq_table);
+free_cdev:
+	kfree(devfreq_dev);
+
+	return cool_dev;
+}
+
+/**
+ * of_devfreq_cooling_register - function to create devfreq cooling device.
+ * @np:		a valid struct device_node to the cooling device tree node
+ * @devfreq:	the devfreq instance.
+ *
+ * This interface function registers the devfreq cooling device with the name
+ * "thermal-devfreq-%x". This api can support multiple instances of devfreq
+ * cooling devices. Using this API, the devfreq cooling device will be
+ * linked to the device tree node provided.
+ *
+ * Return: a valid struct thermal_cooling_device pointer on success,
+ * on failure, it returns a corresponding ERR_PTR().
+ */
+struct thermal_cooling_device *
+of_devfreq_cooling_register(struct device_node *np, struct devfreq *devfreq)
+{
+	if (!np || !devfreq)
+		return ERR_PTR(-EINVAL);
+
+	return __devfreq_cooling_register(np, devfreq);
+}
+EXPORT_SYMBOL_GPL(of_devfreq_cooling_register);
+
+/**
+ * devfreq_cooling_register - function to create devfreq cooling device.
+ * @devfreq:	the devfreq instance.
+ *
+ * This interface function registers the devfreq cooling device with the name
+ * "thermal-devfreq-%x". This api can support multiple instances of devfreq
+ * cooling devices.
+ *
+ * Return: a valid struct thermal_cooling_device pointer on success,
+ * on failure, it returns a corresponding ERR_PTR().
+ */
+struct thermal_cooling_device *
+devfreq_cooling_register(struct devfreq *devfreq)
+{
+	if (!devfreq)
+		return ERR_PTR(-EINVAL);
+
+	return __devfreq_cooling_register(NULL, devfreq);
+}
+EXPORT_SYMBOL_GPL(devfreq_cooling_register);
+
+/**
+ * devfreq_cooling_unregister - function to remove devfreq cooling device.
+ * @cdev: thermal cooling device pointer.
+ *
+ * This interface function unregisters the "thermal-devfreq-%x" cooling device.
+ */
+void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
+{
+	struct devfreq_cooling_device *devfreq_dev;
+
+	if (!cdev)
+		return;
+
+	devfreq_dev = cdev->devdata;
+
+	thermal_cooling_device_unregister(devfreq_dev->cool_dev);
+	kfree(devfreq_dev->freq_table);
+	kfree(devfreq_dev);
+}
+EXPORT_SYMBOL_GPL(devfreq_cooling_unregister);
diff --git a/include/linux/devfreq-cooling.h b/include/linux/devfreq-cooling.h
new file mode 100644
index 000000000000..eec9c7494e72
--- /dev/null
+++ b/include/linux/devfreq-cooling.h
@@ -0,0 +1,80 @@ 
+/*
+ *  linux/include/linux/devfreq-cooling.h
+ *
+ *  Copyright (C) 2015 Samsung Electronics Co., Ltd
+ *  Author: Chanwoo Choi <cw00.choi@samsung.com>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *  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 __DEVFREQ_COOLING_H__
+#define __DEVFREQ_COOLING_H__
+
+#include <linux/of.h>
+#include <linux/thermal.h>
+#include <linux/devfreq.h>
+
+#ifdef CONFIG_DEVFREQ_THERMAL
+/**
+ * devfreq_cooling_register - function to create devfreq cooling device.
+ * @devfreq:	the devfreq instance.
+ */
+struct thermal_cooling_device *
+devfreq_cooling_register(struct devfreq *devfreq);
+
+/**
+ * of_devfreq_cooling_register - create devfreq cooling device based on DT.
+ * @np:		a valid struct device_node to the cooling device tree node
+ * @devfreq:	the devfreq instance.
+ */
+#ifdef CONFIG_THERMAL_OF
+struct thermal_cooling_device *
+of_devfreq_cooling_register(struct device_node *np, struct devfreq *devfreq);
+#else
+static inline struct thermal_cooling_device *
+of_devfreq_cooling_register(struct device_node *np, struct devfreq *devfreq)
+{
+	return ERR_PTR(-ENOSYS);
+}
+#endif
+
+/**
+ * devfreq_cooling_unregister - function to remove devfreq cooling device.
+ * @cdev: thermal cooling device pointer.
+ */
+void devfreq_cooling_unregister(struct thermal_cooling_device *cdev);
+
+#else /* !CONFIG_DEVFREQ_THERMAL */
+static inline struct thermal_cooling_device *
+devfreq_cooling_register(struct devfreq *devfreq)
+{
+	return ERR_PTR(-ENOSYS);
+}
+static inline struct thermal_cooling_device *
+of_devfreq_cooling_register(struct device_node *np, struct devfreq *devfreq)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline
+void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
+{
+	return;
+}
+#endif	/* CONFIG_DEVFREQ_THERMAL */
+
+#endif /* __DEVFREQ_COOLING_H__ */