sony_acpi: SNC device support for Sony Vaios

From: Bjorn Helgaas <bjorn.helgaas@hp.com>

  Even though the devices claimed by sony_acpi.c can not be hot-plugged, the
  driver registration infrastructure allows the .add() and .remove() methods
  to be called at any time while the driver is registered.  So remove __init
  and __exit from them.

From: Matthew Garrett <mjg59@srcf.ucam.org>

[UBUNTU:acpi/sony] Add FN hotkey support
Source URL of Patch:
http://www.kernel.org/git/?p=linux/kernel/git/bcollins/ubuntu-dapper.git;a=commitdiff;h=7a9b49cba4919e8506604629db03add8e0b85767

Signed-off-by: Ben Collins <bcollins@ubuntu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Mattia Dongili <malattia@linux.it>
Signed-off-by: Len Brown <len.brown@intel.com>

Documentation/acpi/sony_acpi.txt

@@ -0,0 +1,87 @@
+ACPI Sony Notebook Control Driver (SNC) Readme
+----------------------------------------------
+	Copyright (C) 2004- 2005 Stelian Pop <stelian@popies.net>
+
+This mini-driver drives the ACPI SNC device present in the
+ACPI BIOS of the Sony Vaio laptops.
+
+It gives access to some extra laptop functionalities. In
+its current form, this driver is mainly useful for controlling the
+screen brightness, but it may do more in the future.
+
+You should probably start by trying the sonypi driver, and try
+sony_acpi only if sonypi doesn't work for you.
+
+Usage:
+------
+
+Loading the sony_acpi module will create a /proc/acpi/sony/
+directory populated with a couple of files.
+
+You then read/write integer values from/to those files by using
+standard UNIX tools.
+
+The files are:
+	brightness		current screen brightness
+	brightness_default	screen brightness which will be set
+				when the laptop will be rebooted
+	cdpower			power on/off the internal CD drive
+
+Note that some files may be missing if they are not supported
+by your particular laptop model.
+
+Example usage:
+	# echo "1" > /proc/acpi/sony/brightness
+sets the lowest screen brightness,
+	# echo "8" > /proc/acpi/sony/brightness
+sets the highest screen brightness,
+	# cat /proc/acpi/sony/brightness
+retrieves the current screen brightness.
+
+Development:
+------------
+
+If you want to help with the development of this driver (and
+you are not afraid of any side effects doing strange things with
+your ACPI BIOS could have on your laptop), load the driver and
+pass the option 'debug=1'.
+
+REPEAT: DON'T DO THIS IF YOU DON'T LIKE RISKY BUSINESS.
+
+In your kernel logs you will find the list of all ACPI methods
+the SNC device has on your laptop. You can see the GBRT/SBRT methods
+used to get/set the brightness, but there are others.
+
+I HAVE NO IDEA WHAT THOSE METHODS DO.
+
+The sony_acpi driver creates, for some of those methods (the most
+current ones found on several Vaio models), an entry under
+/proc/acpi/sony/, just like the 'brightness' one. You can create
+other entries corresponding to your own laptop methods by further
+editing the source (see the 'sony_acpi_values' table, and add a new
+structure to this table with your get/set method names).
+
+Your mission, should you accept it, is to try finding out what
+those entries are for, by reading/writing random values from/to those
+files and find out what is the impact on your laptop.
+
+Should you find anything interesting, please report it back to me,
+I will not disavow all knowledge of your actions :)
+
+Bugs/Limitations:
+-----------------
+
+* This driver is not based on official documentation from Sony
+  (because there is none), so there is no guarantee this driver
+  will work at all, or do the right thing. Although this hasn't
+  happened to me, this driver could do very bad things to your
+  laptop, including permanent damage.
+
+* The sony_acpi and sonypi drivers do not interact at all. In the
+  future, sonypi could use sony_acpi to do (part of) its business.
+
+* spicctrl, which is the userspace tool used to communicate with the
+  sonypi driver (through /dev/sonypi) does not try to use the
+  sony_acpi driver. In the future, spicctrl could try sonypi first,
+  and if it isn't present, try sony_acpi instead.
+

drivers/acpi/Kconfig

@@ -252,6 +252,20 @@ config ACPI_TOSHIBA
 	  If you have a legacy free Toshiba laptop (such as the Libretto L1
 	  series), say Y.
 
+config ACPI_SONY
+	tristate "Sony Laptop Extras"
+	depends on X86 && ACPI
+	default m
+	  ---help---
+	  This mini-driver drives the ACPI SNC device present in the
+	  ACPI BIOS of the Sony Vaio laptops.
+
+	  It gives access to some extra laptop functionalities. In
+	  its current form, the only thing this driver does is letting
+	  the user set or query the screen brightness.
+
+	  Read <file:Documentation/acpi/sony_acpi.txt> for more information.
+
 config ACPI_CUSTOM_DSDT
 	bool "Include Custom DSDT"
 	depends on !STANDALONE

drivers/acpi/Makefile

@@ -53,6 +53,7 @@ obj-$(CONFIG_ACPI_THERMAL)	+= thermal.o
 obj-$(CONFIG_ACPI_SYSTEM)	+= system.o event.o
 obj-$(CONFIG_ACPI_DEBUG)	+= debug.o
 obj-$(CONFIG_ACPI_NUMA)		+= numa.o
+obj-$(CONFIG_ACPI_SONY)		+= sony_acpi.o
 obj-$(CONFIG_ACPI_ASUS)		+= asus_acpi.o
 obj-$(CONFIG_ACPI_IBM)		+= ibm_acpi.o
 obj-$(CONFIG_ACPI_TOSHIBA)	+= toshiba_acpi.o