| Message ID | 1249547498.2670.499.camel@rzhang-dt (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Thu, 2009-08-06 at 16:31 +0800, Zhang Rui wrote: > Introduce ALS sysfs class device. > > ALS sysfs class device provides a standard sysfs interface > for Ambient Light Sensor devices. > > Only two sysfs I/F are introduced currently. > /sys/class/als/alsX/illuminance: > indicates the amount of light incident upon a specified surface area. > /sys/class/als/alsX/mappings: > exports ambient light illuminance to display luminance mappings > that can be used by an OS to calibrate its ambient light policy > for a given sensor configuration. > The OS can use this information to extrapolate an ALS response curve > - noting that these values may be treated differently depending on the > OS implementation but should be used in some form to calibrate ALS policy. > > Signed-off-by: Zhang Rui <rui.zhang@intel.com> > --- > Documentation/als/sysfs.txt | 138 ++++++++++++++++++++++ > drivers/Kconfig | 2 > drivers/Makefile | 1 > drivers/als/Kconfig | 10 + > drivers/als/Makefile | 5 > drivers/als/als_sys.c | 269 ++++++++++++++++++++++++++++++++++++++++++++ > include/linux/als_sys.h | 57 +++++++++ > 7 files changed, 482 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 I/F for Ambient Light "interface", not "I/F" > + 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 +1,269 @@ > +/* > + * 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"); > + > +#define PREFIX "ALS: " > + > +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 DEVICE_ATTR(desc, 0444, desc_show, NULL); > +static DEVICE_ATTR(illuminance, 0444, illuminance_show, NULL); > + > +#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, > +}; > + > +static void als_release(struct device *dev) { Open brace on next line. > + struct als_device *als = to_als_device(dev); > + > + if (als->desc) > + kfree(als->desc); > + kfree(als); > +} > + > +static struct class als_class = { > + .name = "als", > + .dev_release = als_release, > +}; > + > +/** > + * als_device_update_mappings - update the ambient light illuminance to > + * display luminance adjustment mappings > + */ > +int als_device_update_mappings(struct als_device *als) > +{ > + int old_count = als->count; > + int i; > + struct als_mapping_item *pos, *next; > + int result; > + > + result = als->ops->get_mapping_count(als, &als->count); > + if (result) > + return result; > + > + if (old_count == als->count) > + return 0; > + > + 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; > + } > + 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; > + > + 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); I probably wouldn't bother with these null pointer checks. Your ACPI ALS driver does check for failure, but others may not. If a broken driver supplies a null pointer here, we'll oops pretty fast, and the backtrace will show exactly what the problem is. > + > + 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); > + 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); > + } > + > + /* sys I/F */ > + result = device_create_file(&als->device, &dev_attr_illuminance); > + if (result) > + goto unregister_device; > + > + result = device_create_file(&als->device, &dev_attr_desc); > + if (result) > + goto unregister_device; > + > + return als; > + > +unregister_device: > + device_unregister(&als->device); > + return ERR_PTR(result); > +} > + > +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) > +{ > + if (!als) > + return; Unnecessary null pointer check. > + > + device_remove_file(&als->device, &dev_attr_desc); > + device_remove_file(&als->device, &dev_attr_illuminance); > + > + device_unregister(&als->device); > + return; > +} > + > +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_count) (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; > +}; > + > +int als_device_update_mappings(struct als_device *als); > +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/als/sysfs.txt > =================================================================== > --- /dev/null > +++ linux-2.6/Documentation/als/sysfs.txt > @@ -0,0 +1,138 @@ > +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-*] denotes any positive number starting from 0 You might use just "N" instead of "[0-*]", i.e., "/sys/class/als/alsN" is a common informal shorthand for "als0, als1, als2, etc". > + > +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. > + Eg: ACPI ALS driver gives the full pathname of > + the ALS device in ACPI namespace. > + 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 kenrel. s/kenrel/kernel/ > +A user space application is preferred in this case. > + > +Below is a simple example about how to do ALS mangement in user space. s/about/of/ s/mangement/management/ > + > +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 base-room with the laptop and the ALI changes to 200, s/base-room/basement/ > +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
On Thu, Aug 06, 2009 at 04:31:38PM +0800, Zhang Rui wrote: > > Introduce ALS sysfs class device. > > ALS sysfs class device provides a standard sysfs interface > for Ambient Light Sensor devices. > > Only two sysfs I/F are introduced currently. > /sys/class/als/alsX/illuminance: > indicates the amount of light incident upon a specified surface area. > /sys/class/als/alsX/mappings: > exports ambient light illuminance to display luminance mappings > that can be used by an OS to calibrate its ambient light policy > for a given sensor configuration. > The OS can use this information to extrapolate an ALS response curve > - noting that these values may be treated differently depending on the > OS implementation but should be used in some form to calibrate ALS policy. > > Signed-off-by: Zhang Rui <rui.zhang@intel.com> > --- > Documentation/als/sysfs.txt | 138 ++++++++++++++++++++++ This needs to be in Documentation/ABI instead. thanks, greg k-h -- 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
On Thu, Aug 06, 2009 at 04:31:38PM +0800, Zhang Rui wrote: > +#define PREFIX "ALS: " This is not used. > + /* sys I/F */ > + result = device_create_file(&als->device, &dev_attr_illuminance); > + if (result) > + goto unregister_device; > + > + result = device_create_file(&als->device, &dev_attr_desc); > + if (result) > + goto unregister_device; These should be default attributes for the device, that way they get created before userspace is told the device is there, removing any race conditions you will have otherwise. > + > + return als; > + > +unregister_device: > + device_unregister(&als->device); > + return ERR_PTR(result); And you weren't cleaning up the file if the second one failed. thanks, greg k-h -- 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
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-$(CONFIG_PHONE) += telephony/ Index: linux-2.6/drivers/als/Kconfig =================================================================== --- /dev/null +++ linux-2.6/drivers/als/Kconfig @@ -0,0 +1,10 @@ +# +# Ambient Light Sensor sysfs device configuration +# + +menuconfig ALS + tristate "Ambient Light Sensor sysfs device" + help + This framework provides a generic sysfs I/F for Ambient Light + Sensor devices. + If you want this support, you should say Y or M here. Index: linux-2.6/drivers/als/Makefile =================================================================== --- /dev/null +++ linux-2.6/drivers/als/Makefile @@ -0,0 +1,5 @@ +# +# Makefile for sensor chip drivers. +# + +obj-$(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 +1,269 @@ +/* + * 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"); + +#define PREFIX "ALS: " + +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 DEVICE_ATTR(desc, 0444, desc_show, NULL); +static DEVICE_ATTR(illuminance, 0444, illuminance_show, NULL); + +#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, +}; + +static void als_release(struct device *dev) { + struct als_device *als = to_als_device(dev); + + if (als->desc) + kfree(als->desc); + kfree(als); +} + +static struct class als_class = { + .name = "als", + .dev_release = als_release, +}; + +/** + * als_device_update_mappings - update the ambient light illuminance to + * display luminance adjustment mappings + */ +int als_device_update_mappings(struct als_device *als) +{ + int old_count = als->count; + int i; + struct als_mapping_item *pos, *next; + int result; + + result = als->ops->get_mapping_count(als, &als->count); + if (result) + return result; + + if (old_count == als->count) + return 0; + + 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; + } + 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; + + 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); + 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); + } + + /* sys I/F */ + result = device_create_file(&als->device, &dev_attr_illuminance); + if (result) + goto unregister_device; + + result = device_create_file(&als->device, &dev_attr_desc); + if (result) + goto unregister_device; + + return als; + +unregister_device: + device_unregister(&als->device); + return ERR_PTR(result); +} + +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) +{ + if (!als) + return; + + device_remove_file(&als->device, &dev_attr_desc); + device_remove_file(&als->device, &dev_attr_illuminance); + + device_unregister(&als->device); + return; +} + +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_count) (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; +}; + +int als_device_update_mappings(struct als_device *als); +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/als/sysfs.txt =================================================================== --- /dev/null +++ linux-2.6/Documentation/als/sysfs.txt @@ -0,0 +1,138 @@ +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-*] denotes any positive number starting from 0 + +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. + Eg: ACPI ALS driver gives the full pathname of + the ALS device in ACPI namespace. + 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 kenrel. +A user space application is preferred in this case. + +Below is a simple example about how to do ALS mangement 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 base-room 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". +
Introduce ALS sysfs class device. ALS sysfs class device provides a standard sysfs interface for Ambient Light Sensor devices. Only two sysfs I/F are introduced currently. /sys/class/als/alsX/illuminance: indicates the amount of light incident upon a specified surface area. /sys/class/als/alsX/mappings: exports ambient light illuminance to display luminance mappings that can be used by an OS to calibrate its ambient light policy for a given sensor configuration. The OS can use this information to extrapolate an ALS response curve - noting that these values may be treated differently depending on the OS implementation but should be used in some form to calibrate ALS policy. Signed-off-by: Zhang Rui <rui.zhang@intel.com> --- Documentation/als/sysfs.txt | 138 ++++++++++++++++++++++ drivers/Kconfig | 2 drivers/Makefile | 1 drivers/als/Kconfig | 10 + drivers/als/Makefile | 5 drivers/als/als_sys.c | 269 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/als_sys.h | 57 +++++++++ 7 files changed, 482 insertions(+) -- 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