[RFC] [PATCH v3 1/2] introduce ALS sysfs class

[RFC] [PATCH v3 1/2] introduce ALS sysfs class

[Zhang Rui]

Introduce ALS sysfs class device.

ALS sysfs class device provides a standard sysfs interface
for Ambient Light Sensor devices.

please read Documentation/ABI/testing/sysfs-class-als for detailed sysfs
designs.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
---
 Documentation/ABI/testing/sysfs-class-als |  137 ++++++++++++++++
 drivers/Kconfig                           |    2 
 drivers/Makefile                          |    1 
 drivers/als/Kconfig                       |   10 +
 drivers/als/Makefile                      |    5 
 drivers/als/als_sys.c                     |  256 ++++++++++++++++++++++++++++++
 include/linux/als_sys.h                   |   57 ++++++
 7 files changed, 468 insertions(+)

Index: linux-2.6/drivers/Kconfig
===================================================================
--- linux-2.6.orig/drivers/Kconfig
+++ linux-2.6/drivers/Kconfig
@@ -62,6 +62,8 @@ source "drivers/power/Kconfig"
 
 source "drivers/hwmon/Kconfig"
 
+source "drivers/als/Kconfig"
+
 source "drivers/thermal/Kconfig"
 
 source "drivers/watchdog/Kconfig"
Index: linux-2.6/drivers/Makefile
===================================================================
--- linux-2.6.orig/drivers/Makefile
+++ linux-2.6/drivers/Makefile
@@ -76,6 +76,7 @@ obj-$(CONFIG_PPS)		+= pps/
 obj-$(CONFIG_W1)		+= w1/
 obj-$(CONFIG_POWER_SUPPLY)	+= power/
 obj-$(CONFIG_HWMON)		+= hwmon/
+obj-$(CONFIG_ALS)		+= als/
 obj-$(CONFIG_THERMAL)		+= thermal/
 obj-$(CONFIG_WATCHDOG)		+= watchdog/
 obj-$(CONFIG_PHONE)		+= telephony/
Index: linux-2.6/drivers/als/Kconfig
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/Kconfig
@@ -0,0 +1,10 @@
+#
+# Ambient Light Sensor sysfs device configuration
+#
+
+menuconfig ALS
+	tristate "Ambient Light Sensor sysfs device"
+	help
+	  This framework provides a generic sysfs interface for
+	  Ambient Light Sensor devices.
+	  If you want this support, you should say Y or M here.
Index: linux-2.6/drivers/als/Makefile
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for sensor chip drivers.
+#
+
+obj-$(CONFIG_ALS)		+= als_sys.o
Index: linux-2.6/drivers/als/als_sys.c
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/als_sys.c
@@ -0,0 +1,256 @@
+/*
+ *  als_sys.c - Ambient Light Sensor Sysfs support.
+ *
+ *  Copyright (C) 2009 Intel Corp
+ *  Copyright (C) 2009 Zhang Rui <rui.zhang@intel.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/module.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/als_sys.h>
+
+MODULE_AUTHOR("Zhang Rui");
+MODULE_DESCRIPTION("Ambient Light Sensor sysfs support");
+MODULE_LICENSE("GPL");
+
+struct als_mapping_item {
+	struct kobject kobj;
+	int index;
+	struct list_head node;
+};
+
+/* sys I/F for Ambient Light Sensor */
+
+#define to_als_device(dev) container_of(dev, struct als_device, device)
+
+static ssize_t
+desc_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct als_device *als = to_als_device(dev);
+
+	return sprintf(buf, "%s\n", als->desc ? als->desc : "N/A");
+}
+
+static ssize_t
+illuminance_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct als_device *als = to_als_device(dev);
+	int illuminance;
+	int result;
+
+	result = als->ops->get_illuminance(als, &illuminance);
+	if (result)
+		return result;
+
+	if (!illuminance)
+		return sprintf(buf, "Illuminance below the supported range\n");
+	else if (illuminance == -1)
+		return sprintf(buf, "Illuminance above the supported range\n");
+	else if (illuminance < -1)
+		return -ERANGE;
+	else
+		return sprintf(buf, "%d\n", illuminance);
+}
+
+static struct device_attribute als_attrs[] = {
+	__ATTR(desc, 0444, desc_show, NULL),
+	__ATTR(illuminance, 0444, illuminance_show, NULL),
+	__ATTR_NULL,
+};
+
+static void als_release(struct device *dev)
+{
+	struct als_device *als = to_als_device(dev);
+	struct als_mapping_item *pos, *n;
+
+	if (als->desc)
+		kfree(als->desc);
+	list_for_each_entry_safe(pos, n, &als->mappings, node){
+		list_del(&pos->node);
+		kfree(pos);
+	}
+	kfree(als);
+}
+
+static struct class als_class = {
+	.name = "als",
+	.dev_release = als_release,
+	.dev_attrs = als_attrs,
+};
+
+#define ATTR(_name, _mode)      \
+	struct attribute als_##_name##_attr = {               \
+	.name = __stringify(_name), .mode = _mode, \
+	};
+
+static ATTR(illuminance, 0444);
+static ATTR(adjustment, 0444);
+
+static struct attribute * als_mapping_attrs[] = {
+	&als_illuminance_attr,
+	&als_adjustment_attr,
+	NULL,
+};
+
+static ssize_t show_mapping_info(struct kobject *kobj,
+				       struct attribute *attr, char *buf)
+{
+	struct device *dev = container_of(kobj->parent, struct device, kobj);
+	struct als_device *als = to_als_device(dev);
+	int index, illuminance, adjustment;
+	int result;
+
+	if (!sscanf(kobj->name, "mapping%d", &index))
+		return -EINVAL;
+
+	result = als->ops->get_mapping_info(als, index, &illuminance, &adjustment);
+	if (result)
+		return result;
+
+	return sprintf(buf, "%u\n", (attr == &als_illuminance_attr) ? illuminance : adjustment);
+}
+
+static struct sysfs_ops als_mapping_info_ops = {
+	.show = show_mapping_info,
+	.store = NULL,
+};
+
+static struct kobj_type als_mapping_ktype = {
+	.sysfs_ops = &als_mapping_info_ops,
+	.default_attrs = als_mapping_attrs,
+};
+
+/**
+ * als_device_update_mappings - update the ambient light illuminance to
+ * 				display luminance adjustment mappings
+ */
+int als_device_update_mappings(struct als_device *als, int count)
+{
+	int old_count = als->count;
+	int i;
+	struct als_mapping_item *pos, *next;
+	int result;
+
+	als->count = count;
+	if (old_count == als->count)
+		return 0;
+
+	mutex_lock(&als->lock);
+	if (als->count > old_count)
+		for (i = old_count; i < als->count; i++) {
+			pos = kzalloc(sizeof(struct als_mapping_item), GFP_KERNEL);
+			if (!pos)
+				return -ENOMEM;
+
+			pos->index = i;
+			result = kobject_init_and_add(&pos->kobj, &als_mapping_ktype,
+					&als->device.kobj, "mapping%d", pos->index);
+			if (result)
+				break;
+			list_add_tail(&pos->node, &als->mappings);
+		}
+	else
+		list_for_each_entry_safe(pos, next, &als->mappings, node) {
+			if (pos->index < als->count)
+				continue;
+			list_del(&pos->node);
+			kobject_put(&pos->kobj);
+			kfree(pos);
+		}
+
+	if (result)
+		als->count = i;
+	mutex_unlock(&als->lock);
+	return 0;
+}
+
+EXPORT_SYMBOL(als_device_update_mappings);
+
+/**
+ * als_device_register - register a new Ambient Light Sensor class device
+ * @ops:	standard ALS devices callbacks.
+ * @devdata:	device private data.
+ */
+struct als_device *als_device_register(struct als_device_ops *ops,
+				       char *desc, void *devdata)
+{
+	struct als_device *als;
+	static int als_id;
+	int result;
+
+	if (!ops || !ops->get_illuminance)
+		return ERR_PTR(-EINVAL);
+
+	als = kzalloc(sizeof(struct als_device), GFP_KERNEL);
+	if (!als)
+		return ERR_PTR(-ENOMEM);
+
+	als->ops = ops;
+	als->device.class = &als_class;
+	als->devdata = devdata;
+	als->id = als_id++;
+	INIT_LIST_HEAD(&als->mappings);
+	mutex_init(&als->lock);
+	if (desc) {
+		als->desc = kzalloc(strlen(desc), GFP_KERNEL);
+		if (!als->desc) {
+			kfree(als);
+			return ERR_PTR(-ENOMEM);
+		}
+		strcpy(als->desc, desc);
+	}
+	dev_set_name(&als->device, "als%d", als->id);
+	result = device_register(&als->device);
+	if (result) {
+		if (als->desc)
+			kfree(als->desc);
+		kfree(als);
+		return ERR_PTR(result);
+	}
+
+	return als;
+}
+
+EXPORT_SYMBOL(als_device_register);
+
+/**
+ * als_device_unregister - removes the registered ALS device
+ * @als:	the ALS device to remove.
+ */
+void als_device_unregister(struct als_device *als)
+{
+	device_unregister(&als->device);
+}
+
+EXPORT_SYMBOL(als_device_unregister);
+
+static int __init als_init(void)
+{
+	return class_register(&als_class);
+}
+
+static void __exit als_exit(void)
+{
+	class_unregister(&als_class);
+}
+
+subsys_initcall(als_init);
+module_exit(als_exit);
Index: linux-2.6/include/linux/als_sys.h
===================================================================
--- /dev/null
+++ linux-2.6/include/linux/als_sys.h
@@ -0,0 +1,57 @@
+/*
+ *  als.h  ($Revision: 0 $)
+ *
+ *  Copyright (C) 2009  Intel Corp
+ *  Copyright (C) 2009  Zhang Rui <rui.zhang@intel.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 __ALS_SYS_H__
+#define __ALS_SYS_H__
+
+#include <linux/device.h>
+
+struct als_device;
+
+struct als_device_ops {
+	int (*get_illuminance) (struct als_device *, int *);
+	int (*get_mapping_info) (struct als_device *, int, int *, int *);
+};
+
+struct als_mapping {
+	int illuminance;
+	int adjustment;
+};
+
+struct als_device {
+	int id;
+	int illuminance;
+	struct device device;
+	struct als_device_ops *ops;
+	void *devdata;
+	char *desc;
+	int count;
+	struct list_head mappings;
+	struct mutex lock;
+};
+
+int als_device_update_mappings(struct als_device *, int);
+struct als_device *als_device_register(struct als_device_ops *, char *, void *);
+void als_device_unregister(struct als_device *);
+
+#endif /* __ALS_SYS_H__ */
Index: linux-2.6/Documentation/ABI/testing/sysfs-class-als
===================================================================
--- /dev/null
+++ linux-2.6/Documentation/ABI/testing/sysfs-class-als
@@ -0,0 +1,137 @@
+Ambient Light Sensor Sysfs driver How To
+=========================
+
+Written by Zhang Rui <rui.zhang@intel.com>
+
+Updated: 6 August 2009
+
+Copyright (c)  2009 Intel Corporation
+
+0. Introduction
+
+The generic Ambient Light Sensor sysfs provides a standard interface for ALS devices.
+
+User space can use this interface to get the status of the ambient light environment
+the system is currently in, and get the ambient light illuminance to display luminance
+mappings to calibrate its ambient light policy for a given sensor configuration.
+
+An intelligent ALS application can make ambient light decisions based on inputs
+from these ALS attributes and adjust the LVDS brightness levels.
+
+[0-N]	denotes any positive number starting from 0 to N
+
+Two acronyms that used in this HOW TO only:
+ALI	ambient light illuminace
+DLA	display luminance adjustment (or display brightness adjustment)
+
+1. Ambient Light Sensor sysfs driver interface functions
+
+1.1 struct als_device *als_device_register(struct als_device_ops *ops, char *desc, void *devdata)
+
+	This interface function adds a new ALS device to
+	/sys/class/als folder as als[0-*].
+
+	ops:	thermal zone device call-backs.
+		.get_illuminance: get the current ALI.
+		.get_mappings_count: get the number of ALI to DLA mappings.
+		.get_mapping_info: get the info of a specified ALI to DLA mapping.
+	desc:	a description of the ALS device.
+	devdata:device private data
+
+1.2 void als_device_unregister(struct als_device *als)
+
+	This interface function removes the ALS device.
+	It deletes the corresponding entry form /sys/class/als folder.
+
+1.3 int als_device_update_mappings(struct als_device *als)
+
+	This interface updates the ALI to DLA mappings.
+	This is usually invoked by the native ALS driver when it detects a mapping change.
+
+2. sysfs attributes structure
+
+RO	read only value
+RW	read/write value
+
+ALS sysfs attributes will be represented under /sys/class/als.
+
+/sys/class/als/als[0-*]:
+	|-----desc:			Strings which describes the ALS device
+	|-----illuminance:		Current ALI
+	|-----mapping[0-*]:
+		|-----illuminance:	ALI threshold when an DLA is needed
+		|-----adjustment:	how to do the DLA when the threshold is hit
+
+***********************************
+* Ambient Light Sendor attributes *
+***********************************
+
+desc				Strings which descibes the current ALS.
+				This is given by native ALS driver as part of registration.
+				e.g: "acpi_als" for ACPI ALS devices.
+				RO
+				Required
+
+illuminance			Current ALI reported by native ALS driver
+				Unit: lux (lumens per square meter)
+				RO
+				Required
+
+mapping[0-*]			represent one item of the ALI to DLA mappings.
+
+mapping[0-*]/illuminance	ALI threshold when an DLA is needed
+				RO
+
+mapping[0-*]/adjustment		a relative percentages in order simplify the means
+				by which these adjustments are applied in lieu of
+				changes to the user’s display brightness preference.
+				A value of 100 is used to indicate no (0%) display
+				brightness adjustment.
+				Values less than 100 indicate a negative adjustment
+				(dimming); values greater than 100 indicate a positive
+				adjustment (brightening).
+				RO
+
+3. How to implement ALS control in user space
+
+To implement the ALS control, including both ALI detection and Backlight
+adjustment, interactions between backlight driver and als driver are needed.
+It's ugly to implement such a driver in Linux kernel.
+A user space application is preferred in this case.
+
+Below is a simple example of how to do ALS management in user space.
+
+This is the ACPI backlight sysfs I/F
+/sys/class/backlight/acpi_video0:
+	|-----brightness	6
+	|-----actual_brightness	6
+	|-----max_brightness	10
+
+And this is the ACPI ALS sysfs I/F
+/sys/class/als/als0:
+	|-----illuminance		500
+	|-----mapping[0]
+		|-----illuminance	0
+		|-----adjustment	50
+	|-----mapping[1]
+		|-----illuminance	200
+		|-----adjustment	70
+	|-----mapping[2]
+		|-----illuminance	600
+		|-----adjustment	100
+	|-----mapping[3]
+		|-----illuminance	900
+		|-----adjustment	125
+	|-----mapping[4]
+		|-----illuminance	1200
+		|-----adjustment	150
+
+If user thinks that brightness level 6 is good enough for him when ALI is 600,
+he can set brightness 6 as the user’s display brightness preference.
+When user goes to the basement with the laptop and the ALI changes to 200,
+the ALS application knows that it should do a -25% display brightness
+adjustment, i.e. changes the backlight to 4.
+And when the laptop is used outdoors, where the ALI reaches 1200,
+the ALS application should do a +50% adjustment,
+i.e. run "echo 9 > /sys/class/backlight/acpi_video0/brightness".
+


--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[RFC] [PATCH v3 1/2] introduce ALS sysfs class

[Zhang Rui]

Introduce ALS sysfs class device.

ALS sysfs class device provides a standard sysfs interface
for Ambient Light Sensor devices.

please read Documentation/ABI/testing/sysfs-class-als for detailed sysfs
designs.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
---
 Documentation/ABI/testing/sysfs-class-als |  137 ++++++++++++++++
 drivers/Kconfig                           |    2 
 drivers/Makefile                          |    1 
 drivers/als/Kconfig                       |   10 +
 drivers/als/Makefile                      |    5 
 drivers/als/als_sys.c                     |  256 ++++++++++++++++++++++++++++++
 include/linux/als_sys.h                   |   57 ++++++
 7 files changed, 468 insertions(+)

Index: linux-2.6/drivers/Kconfig
===================================================================
--- linux-2.6.orig/drivers/Kconfig
+++ linux-2.6/drivers/Kconfig
@@ -62,6 +62,8 @@ source "drivers/power/Kconfig"
 
 source "drivers/hwmon/Kconfig"
 
+source "drivers/als/Kconfig"
+
 source "drivers/thermal/Kconfig"
 
 source "drivers/watchdog/Kconfig"
Index: linux-2.6/drivers/Makefile
===================================================================
--- linux-2.6.orig/drivers/Makefile
+++ linux-2.6/drivers/Makefile
@@ -76,6 +76,7 @@ obj-$(CONFIG_PPS)		+= pps/
 obj-$(CONFIG_W1)		+= w1/
 obj-$(CONFIG_POWER_SUPPLY)	+= power/
 obj-$(CONFIG_HWMON)		+= hwmon/
+obj-$(CONFIG_ALS)		+= als/
 obj-$(CONFIG_THERMAL)		+= thermal/
 obj-$(CONFIG_WATCHDOG)		+= watchdog/
 obj-$(CONFIG_PHONE)		+= telephony/
Index: linux-2.6/drivers/als/Kconfig
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/Kconfig
@@ -0,0 +1,10 @@
+#
+# Ambient Light Sensor sysfs device configuration
+#
+
+menuconfig ALS
+	tristate "Ambient Light Sensor sysfs device"
+	help
+	  This framework provides a generic sysfs interface for
+	  Ambient Light Sensor devices.
+	  If you want this support, you should say Y or M here.
Index: linux-2.6/drivers/als/Makefile
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for sensor chip drivers.
+#
+
+obj-$(CONFIG_ALS)		+= als_sys.o
Index: linux-2.6/drivers/als/als_sys.c
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/als_sys.c
@@ -0,0 +1,256 @@
+/*
+ *  als_sys.c - Ambient Light Sensor Sysfs support.
+ *
+ *  Copyright (C) 2009 Intel Corp
+ *  Copyright (C) 2009 Zhang Rui <rui.zhang@intel.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/module.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/als_sys.h>
+
+MODULE_AUTHOR("Zhang Rui");
+MODULE_DESCRIPTION("Ambient Light Sensor sysfs support");
+MODULE_LICENSE("GPL");
+
+struct als_mapping_item {
+	struct kobject kobj;
+	int index;
+	struct list_head node;
+};
+
+/* sys I/F for Ambient Light Sensor */
+
+#define to_als_device(dev) container_of(dev, struct als_device, device)
+
+static ssize_t
+desc_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct als_device *als = to_als_device(dev);
+
+	return sprintf(buf, "%s\n", als->desc ? als->desc : "N/A");
+}
+
+static ssize_t
+illuminance_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct als_device *als = to_als_device(dev);
+	int illuminance;
+	int result;
+
+	result = als->ops->get_illuminance(als, &illuminance);
+	if (result)
+		return result;
+
+	if (!illuminance)
+		return sprintf(buf, "Illuminance below the supported range\n");
+	else if (illuminance == -1)
+		return sprintf(buf, "Illuminance above the supported range\n");
+	else if (illuminance < -1)
+		return -ERANGE;
+	else
+		return sprintf(buf, "%d\n", illuminance);
+}
+
+static struct device_attribute als_attrs[] = {
+	__ATTR(desc, 0444, desc_show, NULL),
+	__ATTR(illuminance, 0444, illuminance_show, NULL),
+	__ATTR_NULL,
+};
+
+static void als_release(struct device *dev)
+{
+	struct als_device *als = to_als_device(dev);
+	struct als_mapping_item *pos, *n;
+
+	if (als->desc)
+		kfree(als->desc);
+	list_for_each_entry_safe(pos, n, &als->mappings, node){
+		list_del(&pos->node);
+		kfree(pos);
+	}
+	kfree(als);
+}
+
+static struct class als_class = {
+	.name = "als",
+	.dev_release = als_release,
+	.dev_attrs = als_attrs,
+};
+
+#define ATTR(_name, _mode)      \
+	struct attribute als_##_name##_attr = {               \
+	.name = __stringify(_name), .mode = _mode, \
+	};
+
+static ATTR(illuminance, 0444);
+static ATTR(adjustment, 0444);
+
+static struct attribute * als_mapping_attrs[] = {
+	&als_illuminance_attr,
+	&als_adjustment_attr,
+	NULL,
+};
+
+static ssize_t show_mapping_info(struct kobject *kobj,
+				       struct attribute *attr, char *buf)
+{
+	struct device *dev = container_of(kobj->parent, struct device, kobj);
+	struct als_device *als = to_als_device(dev);
+	int index, illuminance, adjustment;
+	int result;
+
+	if (!sscanf(kobj->name, "mapping%d", &index))
+		return -EINVAL;
+
+	result = als->ops->get_mapping_info(als, index, &illuminance, &adjustment);
+	if (result)
+		return result;
+
+	return sprintf(buf, "%u\n", (attr == &als_illuminance_attr) ? illuminance : adjustment);
+}
+
+static struct sysfs_ops als_mapping_info_ops = {
+	.show = show_mapping_info,
+	.store = NULL,
+};
+
+static struct kobj_type als_mapping_ktype = {
+	.sysfs_ops = &als_mapping_info_ops,
+	.default_attrs = als_mapping_attrs,
+};
+
+/**
+ * als_device_update_mappings - update the ambient light illuminance to
+ * 				display luminance adjustment mappings
+ */
+int als_device_update_mappings(struct als_device *als, int count)
+{
+	int old_count = als->count;
+	int i;
+	struct als_mapping_item *pos, *next;
+	int result;
+
+	als->count = count;
+	if (old_count == als->count)
+		return 0;
+
+	mutex_lock(&als->lock);
+	if (als->count > old_count)
+		for (i = old_count; i < als->count; i++) {
+			pos = kzalloc(sizeof(struct als_mapping_item), GFP_KERNEL);
+			if (!pos)
+				return -ENOMEM;
+
+			pos->index = i;
+			result = kobject_init_and_add(&pos->kobj, &als_mapping_ktype,
+					&als->device.kobj, "mapping%d", pos->index);
+			if (result)
+				break;
+			list_add_tail(&pos->node, &als->mappings);
+		}
+	else
+		list_for_each_entry_safe(pos, next, &als->mappings, node) {
+			if (pos->index < als->count)
+				continue;
+			list_del(&pos->node);
+			kobject_put(&pos->kobj);
+			kfree(pos);
+		}
+
+	if (result)
+		als->count = i;
+	mutex_unlock(&als->lock);
+	return 0;
+}
+
+EXPORT_SYMBOL(als_device_update_mappings);
+
+/**
+ * als_device_register - register a new Ambient Light Sensor class device
+ * @ops:	standard ALS devices callbacks.
+ * @devdata:	device private data.
+ */
+struct als_device *als_device_register(struct als_device_ops *ops,
+				       char *desc, void *devdata)
+{
+	struct als_device *als;
+	static int als_id;
+	int result;
+
+	if (!ops || !ops->get_illuminance)
+		return ERR_PTR(-EINVAL);
+
+	als = kzalloc(sizeof(struct als_device), GFP_KERNEL);
+	if (!als)
+		return ERR_PTR(-ENOMEM);
+
+	als->ops = ops;
+	als->device.class = &als_class;
+	als->devdata = devdata;
+	als->id = als_id++;
+	INIT_LIST_HEAD(&als->mappings);
+	mutex_init(&als->lock);
+	if (desc) {
+		als->desc = kzalloc(strlen(desc), GFP_KERNEL);
+		if (!als->desc) {
+			kfree(als);
+			return ERR_PTR(-ENOMEM);
+		}
+		strcpy(als->desc, desc);
+	}
+	dev_set_name(&als->device, "als%d", als->id);
+	result = device_register(&als->device);
+	if (result) {
+		if (als->desc)
+			kfree(als->desc);
+		kfree(als);
+		return ERR_PTR(result);
+	}
+
+	return als;
+}
+
+EXPORT_SYMBOL(als_device_register);
+
+/**
+ * als_device_unregister - removes the registered ALS device
+ * @als:	the ALS device to remove.
+ */
+void als_device_unregister(struct als_device *als)
+{
+	device_unregister(&als->device);
+}
+
+EXPORT_SYMBOL(als_device_unregister);
+
+static int __init als_init(void)
+{
+	return class_register(&als_class);
+}
+
+static void __exit als_exit(void)
+{
+	class_unregister(&als_class);
+}
+
+subsys_initcall(als_init);
+module_exit(als_exit);
Index: linux-2.6/include/linux/als_sys.h
===================================================================
--- /dev/null
+++ linux-2.6/include/linux/als_sys.h
@@ -0,0 +1,57 @@
+/*
+ *  als.h  ($Revision: 0 $)
+ *
+ *  Copyright (C) 2009  Intel Corp
+ *  Copyright (C) 2009  Zhang Rui <rui.zhang@intel.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 __ALS_SYS_H__
+#define __ALS_SYS_H__
+
+#include <linux/device.h>
+
+struct als_device;
+
+struct als_device_ops {
+	int (*get_illuminance) (struct als_device *, int *);
+	int (*get_mapping_info) (struct als_device *, int, int *, int *);
+};
+
+struct als_mapping {
+	int illuminance;
+	int adjustment;
+};
+
+struct als_device {
+	int id;
+	int illuminance;
+	struct device device;
+	struct als_device_ops *ops;
+	void *devdata;
+	char *desc;
+	int count;
+	struct list_head mappings;
+	struct mutex lock;
+};
+
+int als_device_update_mappings(struct als_device *, int);
+struct als_device *als_device_register(struct als_device_ops *, char *, void *);
+void als_device_unregister(struct als_device *);
+
+#endif /* __ALS_SYS_H__ */
Index: linux-2.6/Documentation/ABI/testing/sysfs-class-als
===================================================================
--- /dev/null
+++ linux-2.6/Documentation/ABI/testing/sysfs-class-als
@@ -0,0 +1,137 @@
+Ambient Light Sensor Sysfs driver How To
+=========================
+
+Written by Zhang Rui <rui.zhang@intel.com>
+
+Updated: 6 August 2009
+
+Copyright (c)  2009 Intel Corporation
+
+0. Introduction
+
+The generic Ambient Light Sensor sysfs provides a standard interface for ALS devices.
+
+User space can use this interface to get the status of the ambient light environment
+the system is currently in, and get the ambient light illuminance to display luminance
+mappings to calibrate its ambient light policy for a given sensor configuration.
+
+An intelligent ALS application can make ambient light decisions based on inputs
+from these ALS attributes and adjust the LVDS brightness levels.
+
+[0-N]	denotes any positive number starting from 0 to N
+
+Two acronyms that used in this HOW TO only:
+ALI	ambient light illuminace
+DLA	display luminance adjustment (or display brightness adjustment)
+
+1. Ambient Light Sensor sysfs driver interface functions
+
+1.1 struct als_device *als_device_register(struct als_device_ops *ops, char *desc, void *devdata)
+
+	This interface function adds a new ALS device to
+	/sys/class/als folder as als[0-*].
+
+	ops:	thermal zone device call-backs.
+		.get_illuminance: get the current ALI.
+		.get_mappings_count: get the number of ALI to DLA mappings.
+		.get_mapping_info: get the info of a specified ALI to DLA mapping.
+	desc:	a description of the ALS device.
+	devdata:device private data
+
+1.2 void als_device_unregister(struct als_device *als)
+
+	This interface function removes the ALS device.
+	It deletes the corresponding entry form /sys/class/als folder.
+
+1.3 int als_device_update_mappings(struct als_device *als)
+
+	This interface updates the ALI to DLA mappings.
+	This is usually invoked by the native ALS driver when it detects a mapping change.
+
+2. sysfs attributes structure
+
+RO	read only value
+RW	read/write value
+
+ALS sysfs attributes will be represented under /sys/class/als.
+
+/sys/class/als/als[0-*]:
+	|-----desc:			Strings which describes the ALS device
+	|-----illuminance:		Current ALI
+	|-----mapping[0-*]:
+		|-----illuminance:	ALI threshold when an DLA is needed
+		|-----adjustment:	how to do the DLA when the threshold is hit
+
+***********************************
+* Ambient Light Sendor attributes *
+***********************************
+
+desc				Strings which descibes the current ALS.
+				This is given by native ALS driver as part of registration.
+				e.g: "acpi_als" for ACPI ALS devices.
+				RO
+				Required
+
+illuminance			Current ALI reported by native ALS driver
+				Unit: lux (lumens per square meter)
+				RO
+				Required
+
+mapping[0-*]			represent one item of the ALI to DLA mappings.
+
+mapping[0-*]/illuminance	ALI threshold when an DLA is needed
+				RO
+
+mapping[0-*]/adjustment		a relative percentages in order simplify the means
+				by which these adjustments are applied in lieu of
+				changes to the user’s display brightness preference.
+				A value of 100 is used to indicate no (0%) display
+				brightness adjustment.
+				Values less than 100 indicate a negative adjustment
+				(dimming); values greater than 100 indicate a positive
+				adjustment (brightening).
+				RO
+
+3. How to implement ALS control in user space
+
+To implement the ALS control, including both ALI detection and Backlight
+adjustment, interactions between backlight driver and als driver are needed.
+It's ugly to implement such a driver in Linux kernel.
+A user space application is preferred in this case.
+
+Below is a simple example of how to do ALS management in user space.
+
+This is the ACPI backlight sysfs I/F
+/sys/class/backlight/acpi_video0:
+	|-----brightness	6
+	|-----actual_brightness	6
+	|-----max_brightness	10
+
+And this is the ACPI ALS sysfs I/F
+/sys/class/als/als0:
+	|-----illuminance		500
+	|-----mapping[0]
+		|-----illuminance	0
+		|-----adjustment	50
+	|-----mapping[1]
+		|-----illuminance	200
+		|-----adjustment	70
+	|-----mapping[2]
+		|-----illuminance	600
+		|-----adjustment	100
+	|-----mapping[3]
+		|-----illuminance	900
+		|-----adjustment	125
+	|-----mapping[4]
+		|-----illuminance	1200
+		|-----adjustment	150
+
+If user thinks that brightness level 6 is good enough for him when ALI is 600,
+he can set brightness 6 as the user’s display brightness preference.
+When user goes to the basement with the laptop and the ALI changes to 200,
+the ALS application knows that it should do a -25% display brightness
+adjustment, i.e. changes the backlight to 4.
+And when the laptop is used outdoors, where the ALI reaches 1200,
+the ALS application should do a +50% adjustment,
+i.e. run "echo 9 > /sys/class/backlight/acpi_video0/brightness".
+

Re: [RFC] [PATCH v3 1/2] introduce ALS sysfs class

[Zhang Rui]

Hi, Pavel,

the current illuminance is not equal to the specified values in the
mappings in most case.
the ALS driver don't have enough knowledge to get a proper display
adjustment, especially that a proper display adjustment would be easy to
select a proper brightness level.
So I think we'd better leave this to user space, which is more flexible.
that's why I still export the mapping info to userspace in this patch.

what do you think?

thanks,
rui

On Wed, 2009-08-19 at 16:40 +0800, Zhang, Rui wrote:
> Introduce ALS sysfs class device.
> 
> ALS sysfs class device provides a standard sysfs interface
> for Ambient Light Sensor devices.
> 
> please read Documentation/ABI/testing/sysfs-class-als for detailed sysfs
> designs.
> 
> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> ---
>  Documentation/ABI/testing/sysfs-class-als |  137 ++++++++++++++++
>  drivers/Kconfig                           |    2
>  drivers/Makefile                          |    1
>  drivers/als/Kconfig                       |   10 +
>  drivers/als/Makefile                      |    5
>  drivers/als/als_sys.c                     |  256 ++++++++++++++++++++++++++++++
>  include/linux/als_sys.h                   |   57 ++++++
>  7 files changed, 468 insertions(+)
> 
> Index: linux-2.6/drivers/Kconfig
> ===================================================================
> --- linux-2.6.orig/drivers/Kconfig
> +++ linux-2.6/drivers/Kconfig
> @@ -62,6 +62,8 @@ source "drivers/power/Kconfig"
> 
>  source "drivers/hwmon/Kconfig"
> 
> +source "drivers/als/Kconfig"
> +
>  source "drivers/thermal/Kconfig"
> 
>  source "drivers/watchdog/Kconfig"
> Index: linux-2.6/drivers/Makefile
> ===================================================================
> --- linux-2.6.orig/drivers/Makefile
> +++ linux-2.6/drivers/Makefile
> @@ -76,6 +76,7 @@ obj-$(CONFIG_PPS)             += pps/
>  obj-$(CONFIG_W1)               += w1/
>  obj-$(CONFIG_POWER_SUPPLY)     += power/
>  obj-$(CONFIG_HWMON)            += hwmon/
> +obj-$(CONFIG_ALS)              += als/
>  obj-$(CONFIG_THERMAL)          += thermal/
>  obj-$(CONFIG_WATCHDOG)         += watchdog/
>  obj-$(CONFIG_PHONE)            += telephony/
> Index: linux-2.6/drivers/als/Kconfig
> ===================================================================
> --- /dev/null
> +++ linux-2.6/drivers/als/Kconfig
> @@ -0,0 +1,10 @@
> +#
> +# Ambient Light Sensor sysfs device configuration
> +#
> +
> +menuconfig ALS
> +       tristate "Ambient Light Sensor sysfs device"
> +       help
> +         This framework provides a generic sysfs interface for
> +         Ambient Light Sensor devices.
> +         If you want this support, you should say Y or M here.
> Index: linux-2.6/drivers/als/Makefile
> ===================================================================
> --- /dev/null
> +++ linux-2.6/drivers/als/Makefile
> @@ -0,0 +1,5 @@
> +#
> +# Makefile for sensor chip drivers.
> +#
> +
> +obj-$(CONFIG_ALS)              += als_sys.o
> Index: linux-2.6/drivers/als/als_sys.c
> ===================================================================
> --- /dev/null
> +++ linux-2.6/drivers/als/als_sys.c
> @@ -0,0 +1,256 @@
> +/*
> + *  als_sys.c - Ambient Light Sensor Sysfs support.
> + *
> + *  Copyright (C) 2009 Intel Corp
> + *  Copyright (C) 2009 Zhang Rui <rui.zhang@intel.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/module.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/als_sys.h>
> +
> +MODULE_AUTHOR("Zhang Rui");
> +MODULE_DESCRIPTION("Ambient Light Sensor sysfs support");
> +MODULE_LICENSE("GPL");
> +
> +struct als_mapping_item {
> +       struct kobject kobj;
> +       int index;
> +       struct list_head node;
> +};
> +
> +/* sys I/F for Ambient Light Sensor */
> +
> +#define to_als_device(dev) container_of(dev, struct als_device, device)
> +
> +static ssize_t
> +desc_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +       struct als_device *als = to_als_device(dev);
> +
> +       return sprintf(buf, "%s\n", als->desc ? als->desc : "N/A");
> +}
> +
> +static ssize_t
> +illuminance_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +       struct als_device *als = to_als_device(dev);
> +       int illuminance;
> +       int result;
> +
> +       result = als->ops->get_illuminance(als, &illuminance);
> +       if (result)
> +               return result;
> +
> +       if (!illuminance)
> +               return sprintf(buf, "Illuminance below the supported range\n");
> +       else if (illuminance == -1)
> +               return sprintf(buf, "Illuminance above the supported range\n");
> +       else if (illuminance < -1)
> +               return -ERANGE;
> +       else
> +               return sprintf(buf, "%d\n", illuminance);
> +}
> +
> +static struct device_attribute als_attrs[] = {
> +       __ATTR(desc, 0444, desc_show, NULL),
> +       __ATTR(illuminance, 0444, illuminance_show, NULL),
> +       __ATTR_NULL,
> +};
> +
> +static void als_release(struct device *dev)
> +{
> +       struct als_device *als = to_als_device(dev);
> +       struct als_mapping_item *pos, *n;
> +
> +       if (als->desc)
> +               kfree(als->desc);
> +       list_for_each_entry_safe(pos, n, &als->mappings, node){
> +               list_del(&pos->node);
> +               kfree(pos);
> +       }
> +       kfree(als);
> +}
> +
> +static struct class als_class = {
> +       .name = "als",
> +       .dev_release = als_release,
> +       .dev_attrs = als_attrs,
> +};
> +
> +#define ATTR(_name, _mode)      \
> +       struct attribute als_##_name##_attr = {               \
> +       .name = __stringify(_name), .mode = _mode, \
> +       };
> +
> +static ATTR(illuminance, 0444);
> +static ATTR(adjustment, 0444);
> +
> +static struct attribute * als_mapping_attrs[] = {
> +       &als_illuminance_attr,
> +       &als_adjustment_attr,
> +       NULL,
> +};
> +
> +static ssize_t show_mapping_info(struct kobject *kobj,
> +                                      struct attribute *attr, char *buf)
> +{
> +       struct device *dev = container_of(kobj->parent, struct device, kobj);
> +       struct als_device *als = to_als_device(dev);
> +       int index, illuminance, adjustment;
> +       int result;
> +
> +       if (!sscanf(kobj->name, "mapping%d", &index))
> +               return -EINVAL;
> +
> +       result = als->ops->get_mapping_info(als, index, &illuminance, &adjustment);
> +       if (result)
> +               return result;
> +
> +       return sprintf(buf, "%u\n", (attr == &als_illuminance_attr) ? illuminance : adjustment);
> +}
> +
> +static struct sysfs_ops als_mapping_info_ops = {
> +       .show = show_mapping_info,
> +       .store = NULL,
> +};
> +
> +static struct kobj_type als_mapping_ktype = {
> +       .sysfs_ops = &als_mapping_info_ops,
> +       .default_attrs = als_mapping_attrs,
> +};
> +
> +/**
> + * als_device_update_mappings - update the ambient light illuminance to
> + *                             display luminance adjustment mappings
> + */
> +int als_device_update_mappings(struct als_device *als, int count)
> +{
> +       int old_count = als->count;
> +       int i;
> +       struct als_mapping_item *pos, *next;
> +       int result;
> +
> +       als->count = count;
> +       if (old_count == als->count)
> +               return 0;
> +
> +       mutex_lock(&als->lock);
> +       if (als->count > old_count)
> +               for (i = old_count; i < als->count; i++) {
> +                       pos = kzalloc(sizeof(struct als_mapping_item), GFP_KERNEL);
> +                       if (!pos)
> +                               return -ENOMEM;
> +
> +                       pos->index = i;
> +                       result = kobject_init_and_add(&pos->kobj, &als_mapping_ktype,
> +                                       &als->device.kobj, "mapping%d", pos->index);
> +                       if (result)
> +                               break;
> +                       list_add_tail(&pos->node, &als->mappings);
> +               }
> +       else
> +               list_for_each_entry_safe(pos, next, &als->mappings, node) {
> +                       if (pos->index < als->count)
> +                               continue;
> +                       list_del(&pos->node);
> +                       kobject_put(&pos->kobj);
> +                       kfree(pos);
> +               }
> +
> +       if (result)
> +               als->count = i;
> +       mutex_unlock(&als->lock);
> +       return 0;
> +}
> +
> +EXPORT_SYMBOL(als_device_update_mappings);
> +
> +/**
> + * als_device_register - register a new Ambient Light Sensor class device
> + * @ops:       standard ALS devices callbacks.
> + * @devdata:   device private data.
> + */
> +struct als_device *als_device_register(struct als_device_ops *ops,
> +                                      char *desc, void *devdata)
> +{
> +       struct als_device *als;
> +       static int als_id;
> +       int result;
> +
> +       if (!ops || !ops->get_illuminance)
> +               return ERR_PTR(-EINVAL);
> +
> +       als = kzalloc(sizeof(struct als_device), GFP_KERNEL);
> +       if (!als)
> +               return ERR_PTR(-ENOMEM);
> +
> +       als->ops = ops;
> +       als->device.class = &als_class;
> +       als->devdata = devdata;
> +       als->id = als_id++;
> +       INIT_LIST_HEAD(&als->mappings);
> +       mutex_init(&als->lock);
> +       if (desc) {
> +               als->desc = kzalloc(strlen(desc), GFP_KERNEL);
> +               if (!als->desc) {
> +                       kfree(als);
> +                       return ERR_PTR(-ENOMEM);
> +               }
> +               strcpy(als->desc, desc);
> +       }
> +       dev_set_name(&als->device, "als%d", als->id);
> +       result = device_register(&als->device);
> +       if (result) {
> +               if (als->desc)
> +                       kfree(als->desc);
> +               kfree(als);
> +               return ERR_PTR(result);
> +       }
> +
> +       return als;
> +}
> +
> +EXPORT_SYMBOL(als_device_register);
> +
> +/**
> + * als_device_unregister - removes the registered ALS device
> + * @als:       the ALS device to remove.
> + */
> +void als_device_unregister(struct als_device *als)
> +{
> +       device_unregister(&als->device);
> +}
> +
> +EXPORT_SYMBOL(als_device_unregister);
> +
> +static int __init als_init(void)
> +{
> +       return class_register(&als_class);
> +}
> +
> +static void __exit als_exit(void)
> +{
> +       class_unregister(&als_class);
> +}
> +
> +subsys_initcall(als_init);
> +module_exit(als_exit);
> Index: linux-2.6/include/linux/als_sys.h
> ===================================================================
> --- /dev/null
> +++ linux-2.6/include/linux/als_sys.h
> @@ -0,0 +1,57 @@
> +/*
> + *  als.h  ($Revision: 0 $)
> + *
> + *  Copyright (C) 2009  Intel Corp
> + *  Copyright (C) 2009  Zhang Rui <rui.zhang@intel.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 __ALS_SYS_H__
> +#define __ALS_SYS_H__
> +
> +#include <linux/device.h>
> +
> +struct als_device;
> +
> +struct als_device_ops {
> +       int (*get_illuminance) (struct als_device *, int *);
> +       int (*get_mapping_info) (struct als_device *, int, int *, int *);
> +};
> +
> +struct als_mapping {
> +       int illuminance;
> +       int adjustment;
> +};
> +
> +struct als_device {
> +       int id;
> +       int illuminance;
> +       struct device device;
> +       struct als_device_ops *ops;
> +       void *devdata;
> +       char *desc;
> +       int count;
> +       struct list_head mappings;
> +       struct mutex lock;
> +};
> +
> +int als_device_update_mappings(struct als_device *, int);
> +struct als_device *als_device_register(struct als_device_ops *, char *, void *);
> +void als_device_unregister(struct als_device *);
> +
> +#endif /* __ALS_SYS_H__ */
> Index: linux-2.6/Documentation/ABI/testing/sysfs-class-als
> ===================================================================
> --- /dev/null
> +++ linux-2.6/Documentation/ABI/testing/sysfs-class-als
> @@ -0,0 +1,137 @@
> +Ambient Light Sensor Sysfs driver How To
> +=========================
> +
> +Written by Zhang Rui <rui.zhang@intel.com>
> +
> +Updated: 6 August 2009
> +
> +Copyright (c)  2009 Intel Corporation
> +
> +0. Introduction
> +
> +The generic Ambient Light Sensor sysfs provides a standard interface for ALS devices.
> +
> +User space can use this interface to get the status of the ambient light environment
> +the system is currently in, and get the ambient light illuminance to display luminance
> +mappings to calibrate its ambient light policy for a given sensor configuration.
> +
> +An intelligent ALS application can make ambient light decisions based on inputs
> +from these ALS attributes and adjust the LVDS brightness levels.
> +
> +[0-N]  denotes any positive number starting from 0 to N
> +
> +Two acronyms that used in this HOW TO only:
> +ALI    ambient light illuminace
> +DLA    display luminance adjustment (or display brightness adjustment)
> +
> +1. Ambient Light Sensor sysfs driver interface functions
> +
> +1.1 struct als_device *als_device_register(struct als_device_ops *ops, char *desc, void *devdata)
> +
> +       This interface function adds a new ALS device to
> +       /sys/class/als folder as als[0-*].
> +
> +       ops:    thermal zone device call-backs.
> +               .get_illuminance: get the current ALI.
> +               .get_mappings_count: get the number of ALI to DLA mappings.
> +               .get_mapping_info: get the info of a specified ALI to DLA mapping.
> +       desc:   a description of the ALS device.
> +       devdata:device private data
> +
> +1.2 void als_device_unregister(struct als_device *als)
> +
> +       This interface function removes the ALS device.
> +       It deletes the corresponding entry form /sys/class/als folder.
> +
> +1.3 int als_device_update_mappings(struct als_device *als)
> +
> +       This interface updates the ALI to DLA mappings.
> +       This is usually invoked by the native ALS driver when it detects a mapping change.
> +
> +2. sysfs attributes structure
> +
> +RO     read only value
> +RW     read/write value
> +
> +ALS sysfs attributes will be represented under /sys/class/als.
> +
> +/sys/class/als/als[0-*]:
> +       |-----desc:                     Strings which describes the ALS device
> +       |-----illuminance:              Current ALI
> +       |-----mapping[0-*]:
> +               |-----illuminance:      ALI threshold when an DLA is needed
> +               |-----adjustment:       how to do the DLA when the threshold is hit
> +
> +***********************************
> +* Ambient Light Sendor attributes *
> +***********************************
> +
> +desc                           Strings which descibes the current ALS.
> +                               This is given by native ALS driver as part of registration.
> +                               e.g: "acpi_als" for ACPI ALS devices.
> +                               RO
> +                               Required
> +
> +illuminance                    Current ALI reported by native ALS driver
> +                               Unit: lux (lumens per square meter)
> +                               RO
> +                               Required
> +
> +mapping[0-*]                   represent one item of the ALI to DLA mappings.
> +
> +mapping[0-*]/illuminance       ALI threshold when an DLA is needed
> +                               RO
> +
> +mapping[0-*]/adjustment                a relative percentages in order simplify the means
> +                               by which these adjustments are applied in lieu of
> +                               changes to the user’s display brightness preference.
> +                               A value of 100 is used to indicate no (0%) display
> +                               brightness adjustment.
> +                               Values less than 100 indicate a negative adjustment
> +                               (dimming); values greater than 100 indicate a positive
> +                               adjustment (brightening).
> +                               RO
> +
> +3. How to implement ALS control in user space
> +
> +To implement the ALS control, including both ALI detection and Backlight
> +adjustment, interactions between backlight driver and als driver are needed.
> +It's ugly to implement such a driver in Linux kernel.
> +A user space application is preferred in this case.
> +
> +Below is a simple example of how to do ALS management in user space.
> +
> +This is the ACPI backlight sysfs I/F
> +/sys/class/backlight/acpi_video0:
> +       |-----brightness        6
> +       |-----actual_brightness 6
> +       |-----max_brightness    10
> +
> +And this is the ACPI ALS sysfs I/F
> +/sys/class/als/als0:
> +       |-----illuminance               500
> +       |-----mapping[0]
> +               |-----illuminance       0
> +               |-----adjustment        50
> +       |-----mapping[1]
> +               |-----illuminance       200
> +               |-----adjustment        70
> +       |-----mapping[2]
> +               |-----illuminance       600
> +               |-----adjustment        100
> +       |-----mapping[3]
> +               |-----illuminance       900
> +               |-----adjustment        125
> +       |-----mapping[4]
> +               |-----illuminance       1200
> +               |-----adjustment        150
> +
> +If user thinks that brightness level 6 is good enough for him when ALI is 600,
> +he can set brightness 6 as the user’s display brightness preference.
> +When user goes to the basement with the laptop and the ALI changes to 200,
> +the ALS application knows that it should do a -25% display brightness
> +adjustment, i.e. changes the backlight to 4.
> +And when the laptop is used outdoors, where the ALI reaches 1200,
> +the ALS application should do a +50% adjustment,
> +i.e. run "echo 9 > /sys/class/backlight/acpi_video0/brightness".
> +
> 
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [RFC] [PATCH v3 1/2] introduce ALS sysfs class

[Zhang Rui]

Hi, Pavel,

the current illuminance is not equal to the specified values in the
mappings in most case.
the ALS driver don't have enough knowledge to get a proper display
adjustment, especially that a proper display adjustment would be easy to
select a proper brightness level.
So I think we'd better leave this to user space, which is more flexible.
that's why I still export the mapping info to userspace in this patch.

what do you think?

thanks,
rui

On Wed, 2009-08-19 at 16:40 +0800, Zhang, Rui wrote:
> Introduce ALS sysfs class device.
> 
> ALS sysfs class device provides a standard sysfs interface
> for Ambient Light Sensor devices.
> 
> please read Documentation/ABI/testing/sysfs-class-als for detailed sysfs
> designs.
> 
> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> ---
>  Documentation/ABI/testing/sysfs-class-als |  137 ++++++++++++++++
>  drivers/Kconfig                           |    2
>  drivers/Makefile                          |    1
>  drivers/als/Kconfig                       |   10 +
>  drivers/als/Makefile                      |    5
>  drivers/als/als_sys.c                     |  256 ++++++++++++++++++++++++++++++
>  include/linux/als_sys.h                   |   57 ++++++
>  7 files changed, 468 insertions(+)
> 
> Index: linux-2.6/drivers/Kconfig
> ===================================================================
> --- linux-2.6.orig/drivers/Kconfig
> +++ linux-2.6/drivers/Kconfig
> @@ -62,6 +62,8 @@ source "drivers/power/Kconfig"
> 
>  source "drivers/hwmon/Kconfig"
> 
> +source "drivers/als/Kconfig"
> +
>  source "drivers/thermal/Kconfig"
> 
>  source "drivers/watchdog/Kconfig"
> Index: linux-2.6/drivers/Makefile
> ===================================================================
> --- linux-2.6.orig/drivers/Makefile
> +++ linux-2.6/drivers/Makefile
> @@ -76,6 +76,7 @@ obj-$(CONFIG_PPS)             += pps/
>  obj-$(CONFIG_W1)               += w1/
>  obj-$(CONFIG_POWER_SUPPLY)     += power/
>  obj-$(CONFIG_HWMON)            += hwmon/
> +obj-$(CONFIG_ALS)              += als/
>  obj-$(CONFIG_THERMAL)          += thermal/
>  obj-$(CONFIG_WATCHDOG)         += watchdog/
>  obj-$(CONFIG_PHONE)            += telephony/
> Index: linux-2.6/drivers/als/Kconfig
> ===================================================================
> --- /dev/null
> +++ linux-2.6/drivers/als/Kconfig
> @@ -0,0 +1,10 @@
> +#
> +# Ambient Light Sensor sysfs device configuration
> +#
> +
> +menuconfig ALS
> +       tristate "Ambient Light Sensor sysfs device"
> +       help
> +         This framework provides a generic sysfs interface for
> +         Ambient Light Sensor devices.
> +         If you want this support, you should say Y or M here.
> Index: linux-2.6/drivers/als/Makefile
> ===================================================================
> --- /dev/null
> +++ linux-2.6/drivers/als/Makefile
> @@ -0,0 +1,5 @@
> +#
> +# Makefile for sensor chip drivers.
> +#
> +
> +obj-$(CONFIG_ALS)              += als_sys.o
> Index: linux-2.6/drivers/als/als_sys.c
> ===================================================================
> --- /dev/null
> +++ linux-2.6/drivers/als/als_sys.c
> @@ -0,0 +1,256 @@
> +/*
> + *  als_sys.c - Ambient Light Sensor Sysfs support.
> + *
> + *  Copyright (C) 2009 Intel Corp
> + *  Copyright (C) 2009 Zhang Rui <rui.zhang@intel.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/module.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/als_sys.h>
> +
> +MODULE_AUTHOR("Zhang Rui");
> +MODULE_DESCRIPTION("Ambient Light Sensor sysfs support");
> +MODULE_LICENSE("GPL");
> +
> +struct als_mapping_item {
> +       struct kobject kobj;
> +       int index;
> +       struct list_head node;
> +};
> +
> +/* sys I/F for Ambient Light Sensor */
> +
> +#define to_als_device(dev) container_of(dev, struct als_device, device)
> +
> +static ssize_t
> +desc_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +       struct als_device *als = to_als_device(dev);
> +
> +       return sprintf(buf, "%s\n", als->desc ? als->desc : "N/A");
> +}
> +
> +static ssize_t
> +illuminance_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +       struct als_device *als = to_als_device(dev);
> +       int illuminance;
> +       int result;
> +
> +       result = als->ops->get_illuminance(als, &illuminance);
> +       if (result)
> +               return result;
> +
> +       if (!illuminance)
> +               return sprintf(buf, "Illuminance below the supported range\n");
> +       else if (illuminance == -1)
> +               return sprintf(buf, "Illuminance above the supported range\n");
> +       else if (illuminance < -1)
> +               return -ERANGE;
> +       else
> +               return sprintf(buf, "%d\n", illuminance);
> +}
> +
> +static struct device_attribute als_attrs[] = {
> +       __ATTR(desc, 0444, desc_show, NULL),
> +       __ATTR(illuminance, 0444, illuminance_show, NULL),
> +       __ATTR_NULL,
> +};
> +
> +static void als_release(struct device *dev)
> +{
> +       struct als_device *als = to_als_device(dev);
> +       struct als_mapping_item *pos, *n;
> +
> +       if (als->desc)
> +               kfree(als->desc);
> +       list_for_each_entry_safe(pos, n, &als->mappings, node){
> +               list_del(&pos->node);
> +               kfree(pos);
> +       }
> +       kfree(als);
> +}
> +
> +static struct class als_class = {
> +       .name = "als",
> +       .dev_release = als_release,
> +       .dev_attrs = als_attrs,
> +};
> +
> +#define ATTR(_name, _mode)      \
> +       struct attribute als_##_name##_attr = {               \
> +       .name = __stringify(_name), .mode = _mode, \
> +       };
> +
> +static ATTR(illuminance, 0444);
> +static ATTR(adjustment, 0444);
> +
> +static struct attribute * als_mapping_attrs[] = {
> +       &als_illuminance_attr,
> +       &als_adjustment_attr,
> +       NULL,
> +};
> +
> +static ssize_t show_mapping_info(struct kobject *kobj,
> +                                      struct attribute *attr, char *buf)
> +{
> +       struct device *dev = container_of(kobj->parent, struct device, kobj);
> +       struct als_device *als = to_als_device(dev);
> +       int index, illuminance, adjustment;
> +       int result;
> +
> +       if (!sscanf(kobj->name, "mapping%d", &index))
> +               return -EINVAL;
> +
> +       result = als->ops->get_mapping_info(als, index, &illuminance, &adjustment);
> +       if (result)
> +               return result;
> +
> +       return sprintf(buf, "%u\n", (attr == &als_illuminance_attr) ? illuminance : adjustment);
> +}
> +
> +static struct sysfs_ops als_mapping_info_ops = {
> +       .show = show_mapping_info,
> +       .store = NULL,
> +};
> +
> +static struct kobj_type als_mapping_ktype = {
> +       .sysfs_ops = &als_mapping_info_ops,
> +       .default_attrs = als_mapping_attrs,
> +};
> +
> +/**
> + * als_device_update_mappings - update the ambient light illuminance to
> + *                             display luminance adjustment mappings
> + */
> +int als_device_update_mappings(struct als_device *als, int count)
> +{
> +       int old_count = als->count;
> +       int i;
> +       struct als_mapping_item *pos, *next;
> +       int result;
> +
> +       als->count = count;
> +       if (old_count == als->count)
> +               return 0;
> +
> +       mutex_lock(&als->lock);
> +       if (als->count > old_count)
> +               for (i = old_count; i < als->count; i++) {
> +                       pos = kzalloc(sizeof(struct als_mapping_item), GFP_KERNEL);
> +                       if (!pos)
> +                               return -ENOMEM;
> +
> +                       pos->index = i;
> +                       result = kobject_init_and_add(&pos->kobj, &als_mapping_ktype,
> +                                       &als->device.kobj, "mapping%d", pos->index);
> +                       if (result)
> +                               break;
> +                       list_add_tail(&pos->node, &als->mappings);
> +               }
> +       else
> +               list_for_each_entry_safe(pos, next, &als->mappings, node) {
> +                       if (pos->index < als->count)
> +                               continue;
> +                       list_del(&pos->node);
> +                       kobject_put(&pos->kobj);
> +                       kfree(pos);
> +               }
> +
> +       if (result)
> +               als->count = i;
> +       mutex_unlock(&als->lock);
> +       return 0;
> +}
> +
> +EXPORT_SYMBOL(als_device_update_mappings);
> +
> +/**
> + * als_device_register - register a new Ambient Light Sensor class device
> + * @ops:       standard ALS devices callbacks.
> + * @devdata:   device private data.
> + */
> +struct als_device *als_device_register(struct als_device_ops *ops,
> +                                      char *desc, void *devdata)
> +{
> +       struct als_device *als;
> +       static int als_id;
> +       int result;
> +
> +       if (!ops || !ops->get_illuminance)
> +               return ERR_PTR(-EINVAL);
> +
> +       als = kzalloc(sizeof(struct als_device), GFP_KERNEL);
> +       if (!als)
> +               return ERR_PTR(-ENOMEM);
> +
> +       als->ops = ops;
> +       als->device.class = &als_class;
> +       als->devdata = devdata;
> +       als->id = als_id++;
> +       INIT_LIST_HEAD(&als->mappings);
> +       mutex_init(&als->lock);
> +       if (desc) {
> +               als->desc = kzalloc(strlen(desc), GFP_KERNEL);
> +               if (!als->desc) {
> +                       kfree(als);
> +                       return ERR_PTR(-ENOMEM);
> +               }
> +               strcpy(als->desc, desc);
> +       }
> +       dev_set_name(&als->device, "als%d", als->id);
> +       result = device_register(&als->device);
> +       if (result) {
> +               if (als->desc)
> +                       kfree(als->desc);
> +               kfree(als);
> +               return ERR_PTR(result);
> +       }
> +
> +       return als;
> +}
> +
> +EXPORT_SYMBOL(als_device_register);
> +
> +/**
> + * als_device_unregister - removes the registered ALS device
> + * @als:       the ALS device to remove.
> + */
> +void als_device_unregister(struct als_device *als)
> +{
> +       device_unregister(&als->device);
> +}
> +
> +EXPORT_SYMBOL(als_device_unregister);
> +
> +static int __init als_init(void)
> +{
> +       return class_register(&als_class);
> +}
> +
> +static void __exit als_exit(void)
> +{
> +       class_unregister(&als_class);
> +}
> +
> +subsys_initcall(als_init);
> +module_exit(als_exit);
> Index: linux-2.6/include/linux/als_sys.h
> ===================================================================
> --- /dev/null
> +++ linux-2.6/include/linux/als_sys.h
> @@ -0,0 +1,57 @@
> +/*
> + *  als.h  ($Revision: 0 $)
> + *
> + *  Copyright (C) 2009  Intel Corp
> + *  Copyright (C) 2009  Zhang Rui <rui.zhang@intel.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 __ALS_SYS_H__
> +#define __ALS_SYS_H__
> +
> +#include <linux/device.h>
> +
> +struct als_device;
> +
> +struct als_device_ops {
> +       int (*get_illuminance) (struct als_device *, int *);
> +       int (*get_mapping_info) (struct als_device *, int, int *, int *);
> +};
> +
> +struct als_mapping {
> +       int illuminance;
> +       int adjustment;
> +};
> +
> +struct als_device {
> +       int id;
> +       int illuminance;
> +       struct device device;
> +       struct als_device_ops *ops;
> +       void *devdata;
> +       char *desc;
> +       int count;
> +       struct list_head mappings;
> +       struct mutex lock;
> +};
> +
> +int als_device_update_mappings(struct als_device *, int);
> +struct als_device *als_device_register(struct als_device_ops *, char *, void *);
> +void als_device_unregister(struct als_device *);
> +
> +#endif /* __ALS_SYS_H__ */
> Index: linux-2.6/Documentation/ABI/testing/sysfs-class-als
> ===================================================================
> --- /dev/null
> +++ linux-2.6/Documentation/ABI/testing/sysfs-class-als
> @@ -0,0 +1,137 @@
> +Ambient Light Sensor Sysfs driver How To
> +=========================
> +
> +Written by Zhang Rui <rui.zhang@intel.com>
> +
> +Updated: 6 August 2009
> +
> +Copyright (c)  2009 Intel Corporation
> +
> +0. Introduction
> +
> +The generic Ambient Light Sensor sysfs provides a standard interface for ALS devices.
> +
> +User space can use this interface to get the status of the ambient light environment
> +the system is currently in, and get the ambient light illuminance to display luminance
> +mappings to calibrate its ambient light policy for a given sensor configuration.
> +
> +An intelligent ALS application can make ambient light decisions based on inputs
> +from these ALS attributes and adjust the LVDS brightness levels.
> +
> +[0-N]  denotes any positive number starting from 0 to N
> +
> +Two acronyms that used in this HOW TO only:
> +ALI    ambient light illuminace
> +DLA    display luminance adjustment (or display brightness adjustment)
> +
> +1. Ambient Light Sensor sysfs driver interface functions
> +
> +1.1 struct als_device *als_device_register(struct als_device_ops *ops, char *desc, void *devdata)
> +
> +       This interface function adds a new ALS device to
> +       /sys/class/als folder as als[0-*].
> +
> +       ops:    thermal zone device call-backs.
> +               .get_illuminance: get the current ALI.
> +               .get_mappings_count: get the number of ALI to DLA mappings.
> +               .get_mapping_info: get the info of a specified ALI to DLA mapping.
> +       desc:   a description of the ALS device.
> +       devdata:device private data
> +
> +1.2 void als_device_unregister(struct als_device *als)
> +
> +       This interface function removes the ALS device.
> +       It deletes the corresponding entry form /sys/class/als folder.
> +
> +1.3 int als_device_update_mappings(struct als_device *als)
> +
> +       This interface updates the ALI to DLA mappings.
> +       This is usually invoked by the native ALS driver when it detects a mapping change.
> +
> +2. sysfs attributes structure
> +
> +RO     read only value
> +RW     read/write value
> +
> +ALS sysfs attributes will be represented under /sys/class/als.
> +
> +/sys/class/als/als[0-*]:
> +       |-----desc:                     Strings which describes the ALS device
> +       |-----illuminance:              Current ALI
> +       |-----mapping[0-*]:
> +               |-----illuminance:      ALI threshold when an DLA is needed
> +               |-----adjustment:       how to do the DLA when the threshold is hit
> +
> +***********************************
> +* Ambient Light Sendor attributes *
> +***********************************
> +
> +desc                           Strings which descibes the current ALS.
> +                               This is given by native ALS driver as part of registration.
> +                               e.g: "acpi_als" for ACPI ALS devices.
> +                               RO
> +                               Required
> +
> +illuminance                    Current ALI reported by native ALS driver
> +                               Unit: lux (lumens per square meter)
> +                               RO
> +                               Required
> +
> +mapping[0-*]                   represent one item of the ALI to DLA mappings.
> +
> +mapping[0-*]/illuminance       ALI threshold when an DLA is needed
> +                               RO
> +
> +mapping[0-*]/adjustment                a relative percentages in order simplify the means
> +                               by which these adjustments are applied in lieu of
> +                               changes to the user’s display brightness preference.
> +                               A value of 100 is used to indicate no (0%) display
> +                               brightness adjustment.
> +                               Values less than 100 indicate a negative adjustment
> +                               (dimming); values greater than 100 indicate a positive
> +                               adjustment (brightening).
> +                               RO
> +
> +3. How to implement ALS control in user space
> +
> +To implement the ALS control, including both ALI detection and Backlight
> +adjustment, interactions between backlight driver and als driver are needed.
> +It's ugly to implement such a driver in Linux kernel.
> +A user space application is preferred in this case.
> +
> +Below is a simple example of how to do ALS management in user space.
> +
> +This is the ACPI backlight sysfs I/F
> +/sys/class/backlight/acpi_video0:
> +       |-----brightness        6
> +       |-----actual_brightness 6
> +       |-----max_brightness    10
> +
> +And this is the ACPI ALS sysfs I/F
> +/sys/class/als/als0:
> +       |-----illuminance               500
> +       |-----mapping[0]
> +               |-----illuminance       0
> +               |-----adjustment        50
> +       |-----mapping[1]
> +               |-----illuminance       200
> +               |-----adjustment        70
> +       |-----mapping[2]
> +               |-----illuminance       600
> +               |-----adjustment        100
> +       |-----mapping[3]
> +               |-----illuminance       900
> +               |-----adjustment        125
> +       |-----mapping[4]
> +               |-----illuminance       1200
> +               |-----adjustment        150
> +
> +If user thinks that brightness level 6 is good enough for him when ALI is 600,
> +he can set brightness 6 as the user’s display brightness preference.
> +When user goes to the basement with the laptop and the ALI changes to 200,
> +the ALS application knows that it should do a -25% display brightness
> +adjustment, i.e. changes the backlight to 4.
> +And when the laptop is used outdoors, where the ALI reaches 1200,
> +the ALS application should do a +50% adjustment,
> +i.e. run "echo 9 > /sys/class/backlight/acpi_video0/brightness".
> +
> 
> 

Re: [RFC] [PATCH v3 1/2] introduce ALS sysfs class

[Greg KH]

On Wed, Aug 19, 2009 at 04:40:29PM +0800, Zhang Rui wrote:
> --- /dev/null
> +++ linux-2.6/Documentation/ABI/testing/sysfs-class-als
> @@ -0,0 +1,137 @@
> +Ambient Light Sensor Sysfs driver How To
> +=========================

<snip>

While this is a nice document, it does not follow the standard that the
files in Documentation/ABI/ should be in.  Can you please read
Documentation/ABI/README and convert the file to follow that?

thanks,

greg k-h

Re: [RFC] [PATCH v3 1/2] introduce ALS sysfs class

[Zhang Rui]

On Thu, 2009-08-20 at 00:01 +0800, Greg KH wrote:
> On Wed, Aug 19, 2009 at 04:40:29PM +0800, Zhang Rui wrote:
> > --- /dev/null
> > +++ linux-2.6/Documentation/ABI/testing/sysfs-class-als
> > @@ -0,0 +1,137 @@
> > +Ambient Light Sensor Sysfs driver How To
> > +=========================
> 
> <snip>
> 
> While this is a nice document, it does not follow the standard that the
> files in Documentation/ABI/ should be in.  Can you please read
> Documentation/ABI/README and convert the file to follow that?
> 
sure. done
refreshed patch attached.

Introduce ALS sysfs class device.

ALS sysfs class device provides a standard sysfs interface
for Ambient Light Sensor devices.

please read Documentation/ABI/testing/sysfs-class-als for detailed sysfs
designs.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
---
 Documentation/ABI/testing/sysfs-class-als |   47 +++++
 drivers/Kconfig                           |    2 
 drivers/Makefile                          |    1 
 drivers/als/Kconfig                       |   10 +
 drivers/als/Makefile                      |    5 
 drivers/als/als_sys.c                     |  256 ++++++++++++++++++++++++++++++
 include/linux/als_sys.h                   |   57 ++++++
 7 files changed, 378 insertions(+)

Index: linux-2.6/drivers/Kconfig
===================================================================
--- linux-2.6.orig/drivers/Kconfig
+++ linux-2.6/drivers/Kconfig
@@ -62,6 +62,8 @@ source "drivers/power/Kconfig"
 
 source "drivers/hwmon/Kconfig"
 
+source "drivers/als/Kconfig"
+
 source "drivers/thermal/Kconfig"
 
 source "drivers/watchdog/Kconfig"
Index: linux-2.6/drivers/Makefile
===================================================================
--- linux-2.6.orig/drivers/Makefile
+++ linux-2.6/drivers/Makefile
@@ -76,6 +76,7 @@ obj-$(CONFIG_PPS)		+= pps/
 obj-$(CONFIG_W1)		+= w1/
 obj-$(CONFIG_POWER_SUPPLY)	+= power/
 obj-$(CONFIG_HWMON)		+= hwmon/
+obj-$(CONFIG_ALS)		+= als/
 obj-$(CONFIG_THERMAL)		+= thermal/
 obj-$(CONFIG_WATCHDOG)		+= watchdog/
 obj-$(CONFIG_PHONE)		+= telephony/
Index: linux-2.6/drivers/als/Kconfig
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/Kconfig
@@ -0,0 +1,10 @@
+#
+# Ambient Light Sensor sysfs device configuration
+#
+
+menuconfig ALS
+	tristate "Ambient Light Sensor sysfs device"
+	help
+	  This framework provides a generic sysfs interface for
+	  Ambient Light Sensor devices.
+	  If you want this support, you should say Y or M here.
Index: linux-2.6/drivers/als/Makefile
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for sensor chip drivers.
+#
+
+obj-$(CONFIG_ALS)		+= als_sys.o
Index: linux-2.6/drivers/als/als_sys.c
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/als_sys.c
@@ -0,0 +1,256 @@
+/*
+ *  als_sys.c - Ambient Light Sensor Sysfs support.
+ *
+ *  Copyright (C) 2009 Intel Corp
+ *  Copyright (C) 2009 Zhang Rui <rui.zhang@intel.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/module.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/als_sys.h>
+
+MODULE_AUTHOR("Zhang Rui");
+MODULE_DESCRIPTION("Ambient Light Sensor sysfs support");
+MODULE_LICENSE("GPL");
+
+struct als_mapping_item {
+	struct kobject kobj;
+	int index;
+	struct list_head node;
+};
+
+/* sys I/F for Ambient Light Sensor */
+
+#define to_als_device(dev) container_of(dev, struct als_device, device)
+
+static ssize_t
+desc_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct als_device *als = to_als_device(dev);
+
+	return sprintf(buf, "%s\n", als->desc ? als->desc : "N/A");
+}
+
+static ssize_t
+illuminance_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct als_device *als = to_als_device(dev);
+	int illuminance;
+	int result;
+
+	result = als->ops->get_illuminance(als, &illuminance);
+	if (result)
+		return result;
+
+	if (!illuminance)
+		return sprintf(buf, "Illuminance below the supported range\n");
+	else if (illuminance == -1)
+		return sprintf(buf, "Illuminance above the supported range\n");
+	else if (illuminance < -1)
+		return -ERANGE;
+	else
+		return sprintf(buf, "%d\n", illuminance);
+}
+
+static struct device_attribute als_attrs[] = {
+	__ATTR(desc, 0444, desc_show, NULL),
+	__ATTR(illuminance, 0444, illuminance_show, NULL),
+	__ATTR_NULL,
+};
+
+static void als_release(struct device *dev)
+{
+	struct als_device *als = to_als_device(dev);
+	struct als_mapping_item *pos, *n;
+
+	if (als->desc)
+		kfree(als->desc);
+	list_for_each_entry_safe(pos, n, &als->mappings, node){
+		list_del(&pos->node);
+		kfree(pos);
+	}
+	kfree(als);
+}
+
+static struct class als_class = {
+	.name = "als",
+	.dev_release = als_release,
+	.dev_attrs = als_attrs,
+};
+
+#define ATTR(_name, _mode)      \
+	struct attribute als_##_name##_attr = {               \
+	.name = __stringify(_name), .mode = _mode, \
+	};
+
+static ATTR(illuminance, 0444);
+static ATTR(adjustment, 0444);
+
+static struct attribute * als_mapping_attrs[] = {
+	&als_illuminance_attr,
+	&als_adjustment_attr,
+	NULL,
+};
+
+static ssize_t show_mapping_info(struct kobject *kobj,
+				       struct attribute *attr, char *buf)
+{
+	struct device *dev = container_of(kobj->parent, struct device, kobj);
+	struct als_device *als = to_als_device(dev);
+	int index, illuminance, adjustment;
+	int result;
+
+	if (!sscanf(kobj->name, "mapping%d", &index))
+		return -EINVAL;
+
+	result = als->ops->get_mapping_info(als, index, &illuminance, &adjustment);
+	if (result)
+		return result;
+
+	return sprintf(buf, "%u\n", (attr == &als_illuminance_attr) ? illuminance : adjustment);
+}
+
+static struct sysfs_ops als_mapping_info_ops = {
+	.show = show_mapping_info,
+	.store = NULL,
+};
+
+static struct kobj_type als_mapping_ktype = {
+	.sysfs_ops = &als_mapping_info_ops,
+	.default_attrs = als_mapping_attrs,
+};
+
+/**
+ * als_device_update_mappings - update the ambient light illuminance to
+ * 				display luminance adjustment mappings
+ */
+int als_device_update_mappings(struct als_device *als, int count)
+{
+	int old_count = als->count;
+	int i;
+	struct als_mapping_item *pos, *next;
+	int result;
+
+	als->count = count;
+	if (old_count == als->count)
+		return 0;
+
+	mutex_lock(&als->lock);
+	if (als->count > old_count)
+		for (i = old_count; i < als->count; i++) {
+			pos = kzalloc(sizeof(struct als_mapping_item), GFP_KERNEL);
+			if (!pos)
+				return -ENOMEM;
+
+			pos->index = i;
+			result = kobject_init_and_add(&pos->kobj, &als_mapping_ktype,
+					&als->device.kobj, "mapping%d", pos->index);
+			if (result)
+				break;
+			list_add_tail(&pos->node, &als->mappings);
+		}
+	else
+		list_for_each_entry_safe(pos, next, &als->mappings, node) {
+			if (pos->index < als->count)
+				continue;
+			list_del(&pos->node);
+			kobject_put(&pos->kobj);
+			kfree(pos);
+		}
+
+	if (result)
+		als->count = i;
+	mutex_unlock(&als->lock);
+	return 0;
+}
+
+EXPORT_SYMBOL(als_device_update_mappings);
+
+/**
+ * als_device_register - register a new Ambient Light Sensor class device
+ * @ops:	standard ALS devices callbacks.
+ * @devdata:	device private data.
+ */
+struct als_device *als_device_register(struct als_device_ops *ops,
+				       char *desc, void *devdata)
+{
+	struct als_device *als;
+	static int als_id;
+	int result;
+
+	if (!ops || !ops->get_illuminance)
+		return ERR_PTR(-EINVAL);
+
+	als = kzalloc(sizeof(struct als_device), GFP_KERNEL);
+	if (!als)
+		return ERR_PTR(-ENOMEM);
+
+	als->ops = ops;
+	als->device.class = &als_class;
+	als->devdata = devdata;
+	als->id = als_id++;
+	INIT_LIST_HEAD(&als->mappings);
+	mutex_init(&als->lock);
+	if (desc) {
+		als->desc = kzalloc(strlen(desc), GFP_KERNEL);
+		if (!als->desc) {
+			kfree(als);
+			return ERR_PTR(-ENOMEM);
+		}
+		strcpy(als->desc, desc);
+	}
+	dev_set_name(&als->device, "als%d", als->id);
+	result = device_register(&als->device);
+	if (result) {
+		if (als->desc)
+			kfree(als->desc);
+		kfree(als);
+		return ERR_PTR(result);
+	}
+
+	return als;
+}
+
+EXPORT_SYMBOL(als_device_register);
+
+/**
+ * als_device_unregister - removes the registered ALS device
+ * @als:	the ALS device to remove.
+ */
+void als_device_unregister(struct als_device *als)
+{
+	device_unregister(&als->device);
+}
+
+EXPORT_SYMBOL(als_device_unregister);
+
+static int __init als_init(void)
+{
+	return class_register(&als_class);
+}
+
+static void __exit als_exit(void)
+{
+	class_unregister(&als_class);
+}
+
+subsys_initcall(als_init);
+module_exit(als_exit);
Index: linux-2.6/include/linux/als_sys.h
===================================================================
--- /dev/null
+++ linux-2.6/include/linux/als_sys.h
@@ -0,0 +1,57 @@
+/*
+ *  als.h  ($Revision: 0 $)
+ *
+ *  Copyright (C) 2009  Intel Corp
+ *  Copyright (C) 2009  Zhang Rui <rui.zhang@intel.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 __ALS_SYS_H__
+#define __ALS_SYS_H__
+
+#include <linux/device.h>
+
+struct als_device;
+
+struct als_device_ops {
+	int (*get_illuminance) (struct als_device *, int *);
+	int (*get_mapping_info) (struct als_device *, int, int *, int *);
+};
+
+struct als_mapping {
+	int illuminance;
+	int adjustment;
+};
+
+struct als_device {
+	int id;
+	int illuminance;
+	struct device device;
+	struct als_device_ops *ops;
+	void *devdata;
+	char *desc;
+	int count;
+	struct list_head mappings;
+	struct mutex lock;
+};
+
+int als_device_update_mappings(struct als_device *, int);
+struct als_device *als_device_register(struct als_device_ops *, char *, void *);
+void als_device_unregister(struct als_device *);
+
+#endif /* __ALS_SYS_H__ */
Index: linux-2.6/Documentation/ABI/testing/sysfs-class-als
===================================================================
--- /dev/null
+++ linux-2.6/Documentation/ABI/testing/sysfs-class-als
@@ -0,0 +1,47 @@
+What:		/sys/class/als/als[0-N]/desc
+Date:		Aug. 2009
+KernelVersion:	2.6.32
+Contact:	Zhang Rui <rui.zhang@intel.com>
+Description:	Strings which descibes the current Ambient Light Sensor
+		device. This is given by native ALS driver as part of
+		registration. e.g: "acpi_als" for ACPI ALS devices.
+		RO
+
+What:		/sys/class/als/als[0-N]/illuminance
+Date:		Aug. 2009
+KernelVersion:	2.6.32
+Contact:	Zhang Rui <rui.zhang@intel.com>
+Description:	Current Ambient Light Illuminance reported by
+		native ALS driver
+		Unit: lux (lumens per square meter)
+		RO
+
+What:		/sys/class/als/als[0-N]/mapping[0-N]
+Date:		Aug. 2009
+KernelVersion:	2.6.32
+Contact:	Zhang Rui <rui.zhang@intel.com>
+Description:	represent one item of the Ambient Light Illuminance
+		to Display Luminance Adjustment mappings.
+
+What:		/sys/class/als/als[0-N]/mapping[0-N]/illuminance
+Date:		Aug. 2009
+KernelVersion:	2.6.32
+Contact:	Zhang Rui <rui.zhang@intel.com>
+Description:	ambient light illuminance threshold when a display
+		luminance(backlight) adjustment is needed.
+		RO
+
+What:		/sys/class/als/als[0-N]/mapping[0-N]/adjustment
+Date:		Aug. 2009
+KernelVersion:	2.6.32
+Contact:	Zhang Rui <rui.zhang@intel.com>
+Description:	a relative percentages in order simplify the means
+		by which these adjustments are applied in lieu of
+		changes to the user’s display brightness preference.
+		A value of 100 is used to indicate no (0%) display
+		brightness adjustment.
+		Values less than 100 indicate a negative adjustment
+		(dimming); values greater than 100 indicate a positive
+		adjustment (brightening).
+		RO
+



--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [RFC] [PATCH v3 1/2] introduce ALS sysfs class

[Zhang Rui]

On Thu, 2009-08-20 at 00:01 +0800, Greg KH wrote:
> On Wed, Aug 19, 2009 at 04:40:29PM +0800, Zhang Rui wrote:
> > --- /dev/null
> > +++ linux-2.6/Documentation/ABI/testing/sysfs-class-als
> > @@ -0,0 +1,137 @@
> > +Ambient Light Sensor Sysfs driver How To
> > +=========================
> 
> <snip>
> 
> While this is a nice document, it does not follow the standard that the
> files in Documentation/ABI/ should be in.  Can you please read
> Documentation/ABI/README and convert the file to follow that?
> 
sure. done
refreshed patch attached.

Introduce ALS sysfs class device.

ALS sysfs class device provides a standard sysfs interface
for Ambient Light Sensor devices.

please read Documentation/ABI/testing/sysfs-class-als for detailed sysfs
designs.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
---
 Documentation/ABI/testing/sysfs-class-als |   47 +++++
 drivers/Kconfig                           |    2 
 drivers/Makefile                          |    1 
 drivers/als/Kconfig                       |   10 +
 drivers/als/Makefile                      |    5 
 drivers/als/als_sys.c                     |  256 ++++++++++++++++++++++++++++++
 include/linux/als_sys.h                   |   57 ++++++
 7 files changed, 378 insertions(+)

Index: linux-2.6/drivers/Kconfig
===================================================================
--- linux-2.6.orig/drivers/Kconfig
+++ linux-2.6/drivers/Kconfig
@@ -62,6 +62,8 @@ source "drivers/power/Kconfig"
 
 source "drivers/hwmon/Kconfig"
 
+source "drivers/als/Kconfig"
+
 source "drivers/thermal/Kconfig"
 
 source "drivers/watchdog/Kconfig"
Index: linux-2.6/drivers/Makefile
===================================================================
--- linux-2.6.orig/drivers/Makefile
+++ linux-2.6/drivers/Makefile
@@ -76,6 +76,7 @@ obj-$(CONFIG_PPS)		+= pps/
 obj-$(CONFIG_W1)		+= w1/
 obj-$(CONFIG_POWER_SUPPLY)	+= power/
 obj-$(CONFIG_HWMON)		+= hwmon/
+obj-$(CONFIG_ALS)		+= als/
 obj-$(CONFIG_THERMAL)		+= thermal/
 obj-$(CONFIG_WATCHDOG)		+= watchdog/
 obj-$(CONFIG_PHONE)		+= telephony/
Index: linux-2.6/drivers/als/Kconfig
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/Kconfig
@@ -0,0 +1,10 @@
+#
+# Ambient Light Sensor sysfs device configuration
+#
+
+menuconfig ALS
+	tristate "Ambient Light Sensor sysfs device"
+	help
+	  This framework provides a generic sysfs interface for
+	  Ambient Light Sensor devices.
+	  If you want this support, you should say Y or M here.
Index: linux-2.6/drivers/als/Makefile
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for sensor chip drivers.
+#
+
+obj-$(CONFIG_ALS)		+= als_sys.o
Index: linux-2.6/drivers/als/als_sys.c
===================================================================
--- /dev/null
+++ linux-2.6/drivers/als/als_sys.c
@@ -0,0 +1,256 @@
+/*
+ *  als_sys.c - Ambient Light Sensor Sysfs support.
+ *
+ *  Copyright (C) 2009 Intel Corp
+ *  Copyright (C) 2009 Zhang Rui <rui.zhang@intel.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/module.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/als_sys.h>
+
+MODULE_AUTHOR("Zhang Rui");
+MODULE_DESCRIPTION("Ambient Light Sensor sysfs support");
+MODULE_LICENSE("GPL");
+
+struct als_mapping_item {
+	struct kobject kobj;
+	int index;
+	struct list_head node;
+};
+
+/* sys I/F for Ambient Light Sensor */
+
+#define to_als_device(dev) container_of(dev, struct als_device, device)
+
+static ssize_t
+desc_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct als_device *als = to_als_device(dev);
+
+	return sprintf(buf, "%s\n", als->desc ? als->desc : "N/A");
+}
+
+static ssize_t
+illuminance_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct als_device *als = to_als_device(dev);
+	int illuminance;
+	int result;
+
+	result = als->ops->get_illuminance(als, &illuminance);
+	if (result)
+		return result;
+
+	if (!illuminance)
+		return sprintf(buf, "Illuminance below the supported range\n");
+	else if (illuminance == -1)
+		return sprintf(buf, "Illuminance above the supported range\n");
+	else if (illuminance < -1)
+		return -ERANGE;
+	else
+		return sprintf(buf, "%d\n", illuminance);
+}
+
+static struct device_attribute als_attrs[] = {
+	__ATTR(desc, 0444, desc_show, NULL),
+	__ATTR(illuminance, 0444, illuminance_show, NULL),
+	__ATTR_NULL,
+};
+
+static void als_release(struct device *dev)
+{
+	struct als_device *als = to_als_device(dev);
+	struct als_mapping_item *pos, *n;
+
+	if (als->desc)
+		kfree(als->desc);
+	list_for_each_entry_safe(pos, n, &als->mappings, node){
+		list_del(&pos->node);
+		kfree(pos);
+	}
+	kfree(als);
+}
+
+static struct class als_class = {
+	.name = "als",
+	.dev_release = als_release,
+	.dev_attrs = als_attrs,
+};
+
+#define ATTR(_name, _mode)      \
+	struct attribute als_##_name##_attr = {               \
+	.name = __stringify(_name), .mode = _mode, \
+	};
+
+static ATTR(illuminance, 0444);
+static ATTR(adjustment, 0444);
+
+static struct attribute * als_mapping_attrs[] = {
+	&als_illuminance_attr,
+	&als_adjustment_attr,
+	NULL,
+};
+
+static ssize_t show_mapping_info(struct kobject *kobj,
+				       struct attribute *attr, char *buf)
+{
+	struct device *dev = container_of(kobj->parent, struct device, kobj);
+	struct als_device *als = to_als_device(dev);
+	int index, illuminance, adjustment;
+	int result;
+
+	if (!sscanf(kobj->name, "mapping%d", &index))
+		return -EINVAL;
+
+	result = als->ops->get_mapping_info(als, index, &illuminance, &adjustment);
+	if (result)
+		return result;
+
+	return sprintf(buf, "%u\n", (attr == &als_illuminance_attr) ? illuminance : adjustment);
+}
+
+static struct sysfs_ops als_mapping_info_ops = {
+	.show = show_mapping_info,
+	.store = NULL,
+};
+
+static struct kobj_type als_mapping_ktype = {
+	.sysfs_ops = &als_mapping_info_ops,
+	.default_attrs = als_mapping_attrs,
+};
+
+/**
+ * als_device_update_mappings - update the ambient light illuminance to
+ * 				display luminance adjustment mappings
+ */
+int als_device_update_mappings(struct als_device *als, int count)
+{
+	int old_count = als->count;
+	int i;
+	struct als_mapping_item *pos, *next;
+	int result;
+
+	als->count = count;
+	if (old_count == als->count)
+		return 0;
+
+	mutex_lock(&als->lock);
+	if (als->count > old_count)
+		for (i = old_count; i < als->count; i++) {
+			pos = kzalloc(sizeof(struct als_mapping_item), GFP_KERNEL);
+			if (!pos)
+				return -ENOMEM;
+
+			pos->index = i;
+			result = kobject_init_and_add(&pos->kobj, &als_mapping_ktype,
+					&als->device.kobj, "mapping%d", pos->index);
+			if (result)
+				break;
+			list_add_tail(&pos->node, &als->mappings);
+		}
+	else
+		list_for_each_entry_safe(pos, next, &als->mappings, node) {
+			if (pos->index < als->count)
+				continue;
+			list_del(&pos->node);
+			kobject_put(&pos->kobj);
+			kfree(pos);
+		}
+
+	if (result)
+		als->count = i;
+	mutex_unlock(&als->lock);
+	return 0;
+}
+
+EXPORT_SYMBOL(als_device_update_mappings);
+
+/**
+ * als_device_register - register a new Ambient Light Sensor class device
+ * @ops:	standard ALS devices callbacks.
+ * @devdata:	device private data.
+ */
+struct als_device *als_device_register(struct als_device_ops *ops,
+				       char *desc, void *devdata)
+{
+	struct als_device *als;
+	static int als_id;
+	int result;
+
+	if (!ops || !ops->get_illuminance)
+		return ERR_PTR(-EINVAL);
+
+	als = kzalloc(sizeof(struct als_device), GFP_KERNEL);
+	if (!als)
+		return ERR_PTR(-ENOMEM);
+
+	als->ops = ops;
+	als->device.class = &als_class;
+	als->devdata = devdata;
+	als->id = als_id++;
+	INIT_LIST_HEAD(&als->mappings);
+	mutex_init(&als->lock);
+	if (desc) {
+		als->desc = kzalloc(strlen(desc), GFP_KERNEL);
+		if (!als->desc) {
+			kfree(als);
+			return ERR_PTR(-ENOMEM);
+		}
+		strcpy(als->desc, desc);
+	}
+	dev_set_name(&als->device, "als%d", als->id);
+	result = device_register(&als->device);
+	if (result) {
+		if (als->desc)
+			kfree(als->desc);
+		kfree(als);
+		return ERR_PTR(result);
+	}
+
+	return als;
+}
+
+EXPORT_SYMBOL(als_device_register);
+
+/**
+ * als_device_unregister - removes the registered ALS device
+ * @als:	the ALS device to remove.
+ */
+void als_device_unregister(struct als_device *als)
+{
+	device_unregister(&als->device);
+}
+
+EXPORT_SYMBOL(als_device_unregister);
+
+static int __init als_init(void)
+{
+	return class_register(&als_class);
+}
+
+static void __exit als_exit(void)
+{
+	class_unregister(&als_class);
+}
+
+subsys_initcall(als_init);
+module_exit(als_exit);
Index: linux-2.6/include/linux/als_sys.h
===================================================================
--- /dev/null
+++ linux-2.6/include/linux/als_sys.h
@@ -0,0 +1,57 @@
+/*
+ *  als.h  ($Revision: 0 $)
+ *
+ *  Copyright (C) 2009  Intel Corp
+ *  Copyright (C) 2009  Zhang Rui <rui.zhang@intel.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 __ALS_SYS_H__
+#define __ALS_SYS_H__
+
+#include <linux/device.h>
+
+struct als_device;
+
+struct als_device_ops {
+	int (*get_illuminance) (struct als_device *, int *);
+	int (*get_mapping_info) (struct als_device *, int, int *, int *);
+};
+
+struct als_mapping {
+	int illuminance;
+	int adjustment;
+};
+
+struct als_device {
+	int id;
+	int illuminance;
+	struct device device;
+	struct als_device_ops *ops;
+	void *devdata;
+	char *desc;
+	int count;
+	struct list_head mappings;
+	struct mutex lock;
+};
+
+int als_device_update_mappings(struct als_device *, int);
+struct als_device *als_device_register(struct als_device_ops *, char *, void *);
+void als_device_unregister(struct als_device *);
+
+#endif /* __ALS_SYS_H__ */
Index: linux-2.6/Documentation/ABI/testing/sysfs-class-als
===================================================================
--- /dev/null
+++ linux-2.6/Documentation/ABI/testing/sysfs-class-als
@@ -0,0 +1,47 @@
+What:		/sys/class/als/als[0-N]/desc
+Date:		Aug. 2009
+KernelVersion:	2.6.32
+Contact:	Zhang Rui <rui.zhang@intel.com>
+Description:	Strings which descibes the current Ambient Light Sensor
+		device. This is given by native ALS driver as part of
+		registration. e.g: "acpi_als" for ACPI ALS devices.
+		RO
+
+What:		/sys/class/als/als[0-N]/illuminance
+Date:		Aug. 2009
+KernelVersion:	2.6.32
+Contact:	Zhang Rui <rui.zhang@intel.com>
+Description:	Current Ambient Light Illuminance reported by
+		native ALS driver
+		Unit: lux (lumens per square meter)
+		RO
+
+What:		/sys/class/als/als[0-N]/mapping[0-N]
+Date:		Aug. 2009
+KernelVersion:	2.6.32
+Contact:	Zhang Rui <rui.zhang@intel.com>
+Description:	represent one item of the Ambient Light Illuminance
+		to Display Luminance Adjustment mappings.
+
+What:		/sys/class/als/als[0-N]/mapping[0-N]/illuminance
+Date:		Aug. 2009
+KernelVersion:	2.6.32
+Contact:	Zhang Rui <rui.zhang@intel.com>
+Description:	ambient light illuminance threshold when a display
+		luminance(backlight) adjustment is needed.
+		RO
+
+What:		/sys/class/als/als[0-N]/mapping[0-N]/adjustment
+Date:		Aug. 2009
+KernelVersion:	2.6.32
+Contact:	Zhang Rui <rui.zhang@intel.com>
+Description:	a relative percentages in order simplify the means
+		by which these adjustments are applied in lieu of
+		changes to the user’s display brightness preference.
+		A value of 100 is used to indicate no (0%) display
+		brightness adjustment.
+		Values less than 100 indicate a negative adjustment
+		(dimming); values greater than 100 indicate a positive
+		adjustment (brightening).
+		RO
+

Re: [RFC] [PATCH v3 1/2] introduce ALS sysfs class

[Greg KH]

On Fri, Aug 21, 2009 at 09:54:07AM +0800, Zhang Rui wrote:
> ---
>  Documentation/ABI/testing/sysfs-class-als |   47 +++++
>  drivers/Kconfig                           |    2 
>  drivers/Makefile                          |    1 
>  drivers/als/Kconfig                       |   10 +
>  drivers/als/Makefile                      |    5 
>  drivers/als/als_sys.c                     |  256 ++++++++++++++++++++++++++++++
>  include/linux/als_sys.h                   |   57 ++++++

Does this file really need to be in include/linux/ ?

Or could you just put it into drivers/als/ and it would be fine?

thanks,

greg k-h

Re: [RFC] [PATCH v3 1/2] introduce ALS sysfs class

[Zhang Rui]

On Fri, 2009-08-21 at 23:08 +0800, Greg KH wrote:
> On Fri, Aug 21, 2009 at 09:54:07AM +0800, Zhang Rui wrote:
> > ---
> >  Documentation/ABI/testing/sysfs-class-als |   47 +++++
> >  drivers/Kconfig                           |    2 
> >  drivers/Makefile                          |    1 
> >  drivers/als/Kconfig                       |   10 +
> >  drivers/als/Makefile                      |    5 
> >  drivers/als/als_sys.c                     |  256 ++++++++++++++++++++++++++++++
> >  include/linux/als_sys.h                   |   57 ++++++
> 
> Does this file really need to be in include/linux/ ?
> 
> Or could you just put it into drivers/als/ and it would be fine?
> 
I don't think so, because all the other native ALS drivers like ACPI ALS
driver should depend on this header file.

thanks,
rui