Message-ID: <1373378414-28086-3-git-send-email-eduardo.valentin@ti.com>
Date:	Tue, 9 Jul 2013 10:00:12 -0400
From:	Eduardo Valentin <eduardo.valentin@...com>
To:	<linux-pm@...r.kernel.org>, <durgadoss.r@...el.com>,
	<amit.daniel@...sung.com>
CC:	<rui.zhang@...el.com>, Eduardo Valentin <eduardo.valentin@...com>,
	<linux-kernel@...r.kernel.org>
Subject: [RFC PATCH 2/4] thermal: introduce device tree parser

In order to be able to build thermal policies
based on generic sensors, like I2C device, that
can be places in different points on different boards,
there is a need to have a way to feed board dependent
data into the thermal framework.

This patch introduces a thermal data parser for device
tree. The parsed data is used to build thermal zones
and thermal binding parameters. The output data
can then be used to deploy thermal policies.

This patch adds also documentation regarding this
API and how to define define tree nodes to use
this infrastructure.

Cc: Zhang Rui <rui.zhang@...el.com>
Cc: linux-pm@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Eduardo Valentin <eduardo.valentin@...com>
---
 .../devicetree/bindings/thermal/thermal.txt        |  92 +++++
 drivers/thermal/Kconfig                            |  13 +
 drivers/thermal/Makefile                           |   1 +
 drivers/thermal/thermal_dt.c                       | 412 +++++++++++++++++++++
 drivers/thermal/thermal_dt.h                       |  44 +++
 include/linux/thermal.h                            |   3 +
 6 files changed, 565 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/thermal/thermal.txt
 create mode 100644 drivers/thermal/thermal_dt.c
 create mode 100644 drivers/thermal/thermal_dt.h

diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt
new file mode 100644
index 0000000..2c25ab2
--- /dev/null
+++ b/Documentation/devicetree/bindings/thermal/thermal.txt
@@ -0,0 +1,92 @@
+----------------------------------------
+Thermal Framework Device Tree descriptor
+----------------------------------------
+
+This file describes how to define a thermal structure using device tree.
+A thermal structure includes thermal zones and their components, such
+as name, governor, trip points, polling intervals and cooling devices
+binding descriptors. A binding descriptor may contain information on
+how to react, with a cooling stepped action or a weight on a fair share.
+
+****
+trip
+****
+
+The trip node is a node to describe a point in the temperature domain
+in which the system takes an action. This node describes just the point,
+not the action.
+
+A node describing a trip must contain:
+- temperature: the trip temperature level, in milliCelsius.
+- hysteresis: a (low) hysteresis value on 'temperature'. This is a relative
+value, in milliCelsius.
+- type: the trip type. Here is the type mapping:
+	THERMAL_TRIP_ACTIVE = 0
+	THERMAL_TRIP_PASSIVE = 1
+	THERMAL_TRIP_HOT = 2
+	THERMAL_TRIP_CRITICAL = 3
+
+**********
+bind_param
+**********
+
+The bind_param node is a node to describe how cooling devices get assigned
+to trip points of the zone. The cooling devices are expected to be loaded
+in the target system.
+
+A node describing a bind_param must contain:
+- cooling_device: A string with the cooling device name.
+- weight: The 'influence' of a particular cooling device on this zone.
+             This is on a percentage scale. The sum of all these weights
+             (for a particular zone) cannot exceed 100.
+- trip_mask: This is a bit mask that gives the binding relation between
+               this thermal zone and cdev, for a particular trip point.
+               If nth bit is set, then the cdev and thermal zone are bound
+               for trip point n.
+
+************
+thermal_zone
+************
+
+The thermal_zone node is the node containing all the required info
+for describing a thermal zone, including its cdev bindings. The thermal_zone
+node must contain, apart from its own properties, one node containing
+trip nodes and one node containing all the zone bind parameters.
+
+Required properties:
+- type: this is a string containing the zone type. Say 'cpu', 'core', 'mem', etc.
+- mask: Bit string: If 'n'th bit is set, then trip point 'n' is writeable.
+
+- passive_delay: number of milliseconds to wait between polls when
+	performing passive cooling.
+- polling_delay: number of milliseconds to wait between polls when checking
+
+- governor: A string containing the default governor for this zone.
+
+Below is an example:
+thermal_zone {
+            type = "CPU";
+            mask = <0x03>; /* trips writability */
+            passive_delay = <250>; /* milliseconds */
+            polling_delay = <1000>; /* milliseconds */
+            governor = "step_wise";
+            trips {
+                    alert@...000{
+                            temperature = <100000>; /* milliCelsius */
+                            hysteresis = <0>; /* milliCelsius */
+                            type = <1>;
+                    };
+                    crit@...000{
+                            temperature = <125000>; /* milliCelsius */
+                            hysteresis = <0>; /* milliCelsius */
+                            type = <3>;
+                    };
+            };
+            bind_params {
+                    action@0{
+                            cooling_device = "thermal-cpufreq";
+                            weight = <100>; /* percentage */
+                            mask = <0x01>;
+                    };
+            };
+};
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 7fb16bc..753f0dc 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -29,6 +29,19 @@ config THERMAL_HWMON
 	  Say 'Y' here if you want all thermal sensors to
 	  have hwmon sysfs interface too.
 
+config THERMAL_OF
+	bool
+	prompt "APIs to parse thermal data out of device tree"
+	depends on OF
+	default y
+	help
+	  This options provides helpers to add the support to
+	  read and parse thermal data definitions out of the
+	  device tree blob.
+
+	  Say 'Y' here if you need to build thermal infrastructure
+	  based on device tree.
+
 choice
 	prompt "Default Thermal governor"
 	default THERMAL_DEFAULT_GOV_STEP_WISE
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 24cb894..eedb273 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -7,6 +7,7 @@ thermal_sys-y			+= thermal_core.o
 
 # interface to/from other layers providing sensors
 thermal_sys-$(CONFIG_THERMAL_HWMON)		+= thermal_hwmon.o
+thermal_sys-$(CONFIG_THERMAL_OF)		+= thermal_dt.o
 
 # governors
 thermal_sys-$(CONFIG_THERMAL_GOV_FAIR_SHARE)	+= fair_share.o
diff --git a/drivers/thermal/thermal_dt.c b/drivers/thermal/thermal_dt.c
new file mode 100644
index 0000000..6553582
--- /dev/null
+++ b/drivers/thermal/thermal_dt.c
@@ -0,0 +1,412 @@
+/*
+ *  thermal_dt.c - Generic Thermal Management device tree support.
+ *
+ *  Copyright (C) 2013 Texas Instruments
+ *  Copyright (C) 2013 Eduardo Valentin <eduardo.valentin@...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.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+#include <linux/thermal.h>
+#include <linux/slab.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/string.h>
+
+struct __thermal_bind_params {
+	char cooling_device[THERMAL_NAME_LENGTH];
+};
+
+static
+int thermal_of_match(struct thermal_zone_device *tz,
+		     struct thermal_cooling_device *cdev);
+
+static int thermal_of_populate_bind_params(struct device *dev,
+					   struct device_node *node,
+					   struct __thermal_bind_params *__tbp,
+					   struct thermal_bind_params *tbp)
+{
+	const char *cdev_name;
+	int ret;
+	u32 prop;
+
+	ret = of_property_read_u32(node, "weight", &prop);
+	if (ret < 0) {
+		dev_err(dev, "missing weight property\n");
+		return ret;
+	}
+	tbp->weight = prop;
+
+	ret = of_property_read_u32(node, "mask", &prop);
+	if (ret < 0) {
+		dev_err(dev, "missing mask property\n");
+		return ret;
+	}
+	tbp->trip_mask = prop;
+
+	/* this will allow us to bind with cooling devices */
+	tbp->match = thermal_of_match;
+
+	ret = of_property_read_string(node, "cooling_device", &cdev_name);
+	if (ret < 0) {
+		dev_err(dev, "missing cooling_device property\n");
+		return ret;
+	}
+	strncpy(__tbp->cooling_device, cdev_name,
+		sizeof(__tbp->cooling_device));
+
+	return 0;
+}
+
+struct __thermal_trip {
+	unsigned long int temperature;
+	unsigned long int hysteresis;
+	enum thermal_trip_type type;
+};
+
+static
+int thermal_of_populate_trip(struct device *dev,
+			     struct device_node *node,
+			     struct __thermal_trip *trip)
+{
+	int ret;
+	int prop;
+
+	ret = of_property_read_u32(node, "temperature", &prop);
+	if (ret < 0) {
+		dev_err(dev, "missing temperature property\n");
+		return ret;
+	}
+	trip->temperature = prop;
+
+	ret = of_property_read_u32(node, "hysteresis", &prop);
+	if (ret < 0) {
+		dev_err(dev, "missing hysteresis property\n");
+		return ret;
+	}
+	trip->hysteresis = prop;
+
+	ret = of_property_read_u32(node, "type", &prop);
+	if (ret < 0) {
+		dev_err(dev, "missing type property\n");
+		return ret;
+	}
+	trip->type = prop;
+
+	return 0;
+}
+
+struct __thermal_zone_device {
+	enum thermal_device_mode mode;
+	int passive_delay;
+	int polling_delay;
+	int mask;
+	int ntrips;
+	char type[THERMAL_NAME_LENGTH];
+	struct __thermal_trip *trips;
+	struct __thermal_bind_params *bind_params;
+	struct thermal_bind_params *tbps;
+	struct thermal_zone_params zone_params;
+	int (*get_temp)(void *, unsigned long *);
+	void *devdata;
+};
+
+static
+struct __thermal_zone_device *thermal_of_build_thermal_zone(struct device *dev)
+{
+	struct device_node *child, *gchild, *node;
+	struct __thermal_zone_device *tz;
+	const char *name;
+	int ret, i;
+	u32 prop;
+
+	node = dev->of_node;
+	if (!node)
+		return ERR_PTR(-EINVAL);
+
+	node = of_find_node_by_name(node, "thermal_zone");
+	if (!node) {
+		dev_err(dev, "no thermal_zone node found\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	tz = devm_kzalloc(dev, sizeof(*tz), GFP_KERNEL);
+	if (!tz) {
+		dev_err(dev, "not enough memory for thermal of zone\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	ret = of_property_read_u32(node, "passive_delay", &prop);
+	if (ret < 0) {
+		dev_err(dev, "missing passive_delay property\n");
+		return ERR_PTR(ret);
+	}
+	tz->passive_delay = prop;
+
+	ret = of_property_read_u32(node, "polling_delay", &prop);
+	if (ret < 0) {
+		dev_err(dev, "missing polling_delay property\n");
+		return ERR_PTR(ret);
+	}
+	tz->polling_delay = prop;
+
+	ret = of_property_read_u32(node, "mask", &prop);
+	if (ret < 0) {
+		dev_err(dev, "missing mask property\n");
+		return ERR_PTR(ret);
+	}
+	tz->mask = prop;
+
+	ret = of_property_read_string(node, "type", &name);
+	if (ret < 0) {
+		dev_err(dev, "missing type property\n");
+		return ERR_PTR(ret);
+	}
+	strncpy(tz->type, name, sizeof(tz->type));
+
+	ret = of_property_read_string(node, "governor", &name);
+	if (ret < 0) {
+		dev_err(dev, "missing governor property\n");
+		return ERR_PTR(ret);
+	}
+	strncpy(tz->zone_params.governor_name, name,
+		sizeof(tz->zone_params.governor_name));
+
+	/* trips */
+	child = of_find_node_by_name(node, "trips");
+	tz->ntrips = of_get_child_count(child);
+	tz->trips = devm_kzalloc(dev, tz->ntrips * sizeof(*tz->trips),
+				 GFP_KERNEL);
+	if (!tz->trips)
+		return ERR_PTR(-ENOMEM);
+	i = 0;
+	for_each_child_of_node(child, gchild)
+		thermal_of_populate_trip(dev, gchild, &tz->trips[i++]);
+
+	/* bind_params */
+	child = of_find_node_by_name(node, "bind_params");
+	tz->zone_params.num_tbps = of_get_child_count(child);
+	tz->bind_params = devm_kzalloc(dev,
+				       tz->zone_params.num_tbps *
+						sizeof(*tz->bind_params),
+				       GFP_KERNEL);
+	if (!tz->bind_params)
+		return ERR_PTR(-ENOMEM);
+	tz->zone_params.tbp = devm_kzalloc(dev,
+					   tz->zone_params.num_tbps *
+						sizeof(*tz->zone_params.tbp),
+					   GFP_KERNEL);
+	if (!tz->zone_params.tbp)
+		return ERR_PTR(-ENOMEM);
+	i = 0;
+	for_each_child_of_node(child, gchild) {
+		thermal_of_populate_bind_params(dev, gchild,
+						&tz->bind_params[i],
+						&tz->zone_params.tbp[i]);
+		i++;
+	}
+	tz->mode = THERMAL_DEVICE_ENABLED;
+
+	return tz;
+}
+
+static
+int thermal_of_match(struct thermal_zone_device *tz,
+		     struct thermal_cooling_device *cdev)
+{
+	struct __thermal_zone_device *data = tz->devdata;
+	int i;
+
+	for (i = 0; i < data->zone_params.num_tbps; i++) {
+		if (!strncmp(data->bind_params[i].cooling_device,
+			     cdev->type,
+			     strlen(data->bind_params[i].cooling_device)) &&
+		    (data->zone_params.tbp[i].trip_mask & (1 << i)))
+			return 0;
+	}
+
+	return -EINVAL;
+}
+
+static
+int of_thermal_get_temp(struct thermal_zone_device *tz,
+			unsigned long *temp)
+{
+	struct __thermal_zone_device *data = tz->devdata;
+
+	return data->get_temp(data->devdata, temp);
+}
+
+static
+int of_thermal_get_mode(struct thermal_zone_device *tz,
+			enum thermal_device_mode *mode)
+{
+	struct __thermal_zone_device *data = tz->devdata;
+
+	*mode = data->mode;
+
+	return 0;
+}
+
+static
+int of_thermal_set_mode(struct thermal_zone_device *tz,
+			enum thermal_device_mode mode)
+{
+	struct __thermal_zone_device *data = tz->devdata;
+
+	mutex_lock(&tz->lock);
+
+	if (mode == THERMAL_DEVICE_ENABLED)
+		tz->polling_delay = data->polling_delay;
+	else
+		tz->polling_delay = 0;
+
+	mutex_unlock(&tz->lock);
+
+	data->mode = mode;
+	thermal_zone_device_update(tz);
+
+	return 0;
+}
+
+static
+int of_thermal_get_trip_type(struct thermal_zone_device *tz, int trip,
+			     enum thermal_trip_type *type)
+{
+	struct __thermal_zone_device *data = tz->devdata;
+
+	if (trip >= data->ntrips || trip < 0)
+		return -ERANGE;
+
+	*type = data->trips[trip].type;
+
+	return 0;
+}
+
+static
+int of_thermal_get_trip_temp(struct thermal_zone_device *tz, int trip,
+			     unsigned long *temp)
+{
+	struct __thermal_zone_device *data = tz->devdata;
+
+	if (trip >= data->ntrips || trip < 0)
+		return -ERANGE;
+
+	*temp = data->trips[trip].temperature;
+
+	return 0;
+}
+
+static
+int of_thermal_set_trip_temp(struct thermal_zone_device *tz, int trip,
+			     unsigned long temp)
+{
+	struct __thermal_zone_device *data = tz->devdata;
+
+	if (trip >= data->ntrips || trip < 0)
+		return -ERANGE;
+
+	/* thermal fw should take care of data->mask & (1 << trip) */
+	data->trips[trip].temperature = temp;
+
+	return 0;
+}
+
+static
+int of_thermal_get_trip_hyst(struct thermal_zone_device *tz, int trip,
+			     unsigned long *hyst)
+{
+	struct __thermal_zone_device *data = tz->devdata;
+
+	if (trip >= data->ntrips || trip < 0)
+		return -ERANGE;
+
+	*hyst = data->trips[trip].hysteresis;
+
+	return 0;
+}
+
+static
+int of_thermal_set_trip_hyst(struct thermal_zone_device *tz, int trip,
+			     unsigned long hyst)
+{
+	struct __thermal_zone_device *data = tz->devdata;
+
+	if (trip >= data->ntrips || trip < 0)
+		return -ERANGE;
+
+	/* thermal fw should take care of data->mask & (1 << trip) */
+	data->trips[trip].hysteresis = hyst;
+
+	return 0;
+}
+
+static int
+of_thermal_get_crit_temp(struct thermal_zone_device *tz, unsigned long *temp)
+{
+	struct __thermal_zone_device *data = tz->devdata;
+	int i;
+
+	for (i = 0; i < data->ntrips; i++)
+		if (data->trips[i].type == THERMAL_TRIP_CRITICAL) {
+			*temp = data->trips[i].temperature;
+			return 0;
+		}
+
+	return -EINVAL;
+}
+
+static const
+struct thermal_zone_device_ops of_thermal_ops = {
+	.get_temp = of_thermal_get_temp,
+	.get_mode = of_thermal_get_mode,
+	.set_mode = of_thermal_set_mode,
+	.get_trip_type = of_thermal_get_trip_type,
+	.get_trip_temp = of_thermal_get_trip_temp,
+	.set_trip_temp = of_thermal_set_trip_temp,
+	.get_trip_hyst = of_thermal_get_trip_hyst,
+	.set_trip_hyst = of_thermal_set_trip_hyst,
+	.get_crit_temp = of_thermal_get_crit_temp,
+};
+
+struct thermal_zone_device *thermal_zone_of_device_register(struct device *dev,
+		void *data, int (*get_temp)(void *, unsigned long *))
+{
+	struct __thermal_zone_device *tz;
+	struct thermal_zone_device_ops *ops;
+
+	tz = thermal_of_build_thermal_zone(dev);
+	if (IS_ERR(tz)) {
+		dev_err(dev, "failed to build thermal zone\n");
+		return NULL;
+	}
+	ops = devm_kzalloc(dev, sizeof(*ops), GFP_KERNEL);
+	if (!ops) {
+		dev_err(dev, "no memory available for thermal ops\n");
+		return NULL;
+	}
+	memcpy(ops, &of_thermal_ops, sizeof(*ops));
+	tz->get_temp = get_temp;
+	tz->devdata = data;
+
+	return thermal_zone_device_register(tz->type, tz->ntrips, tz->mask, tz,
+					    ops, &tz->zone_params,
+					    tz->passive_delay,
+					    tz->polling_delay);
+}
+EXPORT_SYMBOL_GPL(thermal_zone_of_device_register);
diff --git a/drivers/thermal/thermal_dt.h b/drivers/thermal/thermal_dt.h
new file mode 100644
index 0000000..5491d19
--- /dev/null
+++ b/drivers/thermal/thermal_dt.h
@@ -0,0 +1,44 @@
+/*
+ *  thermal_dt.h - Generic Thermal Management device tree support.
+ *
+ *  Copyright (C) 2013 Texas Instruments
+ *  Copyright (C) 2013 Eduardo Valentin <eduardo.valentin@...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 __THERMAL_DT_H__
+#define __THERMAL_DT_H__
+#include <linux/device.h>
+
+#ifdef CONFIG_THERMAL_OF
+struct thermal_bind_params *thermal_of_build_bind_params(struct device *dev);
+struct thermal_zone_device *thermal_of_build_thermal_zone(struct device *dev);
+#else
+static
+struct thermal_bind_params *thermal_of_build_bind_params(struct device *dev)
+{
+	return NULL;
+}
+
+static
+struct thermal_zone_device *thermal_of_build_thermal_zone(struct device *dev)
+{
+	return NULL;
+}
+#endif
+
+#endif /* __THERMAL_DT_H__ */
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index a386a1c..a62ada0 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -224,6 +224,9 @@ struct thermal_genl_event {
 };
 
 /* Function declarations */
+struct thermal_zone_device
+*thermal_zone_of_device_register(struct device *, void *data,
+	int (*get_temp) (void *, unsigned long *));
 struct thermal_zone_device *thermal_zone_device_register(const char *, int, int,
 		void *, const struct thermal_zone_device_ops *,
 		const struct thermal_zone_params *, int, int);
-- 
1.8.2.1.342.gfa7285d

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