Start handling audio devices via vga_switcheroo

This is an attempt to notify the audio driver (snd-hda-intel) that the
graphics card is being disabled to prevent access to a sleeping device.

TODO:
 - System suspend/resume is not really working properly with this.

Addresses https://github.com/Bumblebee-Project/bbswitch/issues/18

.gitignore

@@ -5,3 +5,5 @@ Module.symvers
 *.mod.c
 *.o
 modules.order
+bbswitch-*.tar.gz
+.*.sw*

COPYING

@@ -0,0 +1,339 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+  To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have.  You must make sure that they, too, receive or can get the
+source code.  And you must show them these terms so they know their
+rights.
+
+  We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+  Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software.  If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+  Finally, any free program is threatened constantly by software
+patents.  We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary.  To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License.  The "Program", below,
+refers to any such program or work, and a "work based on the Program"
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language.  (Hereinafter, translation is included without limitation in
+the term "modification".)  Each licensee is addressed as "you".
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope.  The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+  1. You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+  2. You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+    a) You must cause the modified files to carry prominent notices
+    stating that you changed the files and the date of any change.
+
+    b) You must cause any work that you distribute or publish, that in
+    whole or in part contains or is derived from the Program or any
+    part thereof, to be licensed as a whole at no charge to all third
+    parties under the terms of this License.
+
+    c) If the modified program normally reads commands interactively
+    when run, you must cause it, when started running for such
+    interactive use in the most ordinary way, to print or display an
+    announcement including an appropriate copyright notice and a
+    notice that there is no warranty (or else, saying that you provide
+    a warranty) and that users may redistribute the program under
+    these conditions, and telling the user how to view a copy of this
+    License.  (Exception: if the Program itself is interactive but
+    does not normally print such an announcement, your work based on
+    the Program is not required to print an announcement.)
+
+These requirements apply to the modified work as a whole.  If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works.  But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+  3. You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+    a) Accompany it with the complete corresponding machine-readable
+    source code, which must be distributed under the terms of Sections
+    1 and 2 above on a medium customarily used for software interchange; or,
+
+    b) Accompany it with a written offer, valid for at least three
+    years, to give any third party, for a charge no more than your
+    cost of physically performing source distribution, a complete
+    machine-readable copy of the corresponding source code, to be
+    distributed under the terms of Sections 1 and 2 above on a medium
+    customarily used for software interchange; or,
+
+    c) Accompany it with the information you received as to the offer
+    to distribute corresponding source code.  (This alternative is
+    allowed only for noncommercial distribution and only if you
+    received the program in object code or executable form with such
+    an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for
+making modifications to it.  For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable.  However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+  4. You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+  5. You are not required to accept this License, since you have not
+signed it.  However, nothing else grants you permission to modify or
+distribute the Program or its derivative works.  These actions are
+prohibited by law if you do not accept this License.  Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+  6. Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+  7. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+  9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Program
+specifies a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+                            NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    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; either version 2 of the License, or
+    (at your option) any later version.
+
+    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.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.

Makefile

@@ -5,12 +5,27 @@ KVERSION := $(shell uname -r)
 KDIR := /lib/modules/$(KVERSION)/build
 PWD := "$$(pwd)"
 
+ifdef DEBUG
+CFLAGS_$(obj-m) := -DDEBUG
+endif
+
 default:
 	$(MAKE) -C $(KDIR) M=$(PWD) modules
 
 clean:
-	$(MAKE) -C $(KDIR) M=$(PWD) clean
+	$(MAKE) O=$(PWD) -C $(KDIR) M=$(PWD) clean
 
 load:
-	-/sbin/rmmod $(modname)
-	/sbin/insmod $(modname).ko
+	-rmmod $(modname)
+	insmod $(modname).ko
+
+install:
+	mkdir -p /lib/modules/$(KVERSION)/misc/$(modname)
+	install -m 0755 -o root -g root $(modname).ko /lib/modules/$(KVERSION)/misc/$(modname)
+	depmod -a
+
+uninstall:
+	rm /lib/modules/$(KVERSION)/misc/$(modname)/$(modname).ko
+	rmdir /lib/modules/$(KVERSION)/misc/$(modname)
+	rmdir /lib/modules/$(KVERSION)/misc
+	depmod -a

Makefile.dkms

@@ -13,12 +13,12 @@ src_install:
 	sed 's/#MODULE_VERSION#/$(modver)/' dkms/dkms.conf > '$(DKMS_DEST)/dkms.conf'
 
 build: src_install
-	$(DKMS) build 'bbswitch/$(modver)'
+	$(DKMS) build -m bbswitch -v $(modver)
 
 install: build
-	$(DKMS) install 'bbswitch/$(modver)'
+	$(DKMS) install -m bbswitch -v $(modver)
 
 uninstall:
-	$(DKMS) remove bbswitch/$(modver) --all
+	$(DKMS) remove -m bbswitch -v $(modver) --all
 
 .PHONY: all src_install build install uninstall

NEWS

@@ -1,3 +1,30 @@
+Version 0.8 - 5 December 2013
+
+* Compatibility with Linux 3.13.
+
+Version 0.7 - 28 May 2013
+
+* Fixes a scary WARNING on Linux 3.9.
+* Improved debug information when an ACPI method cannot be executed.
+* Added copyright information, update my name.
+
+Version 0.6 - 19 March 2013
+
+* Add workaround for Linux 3.8 regression (not present in earlier or latter
+  versions) that prevented the video card from turned off unless a driver was
+  loaded before.
+* Compatibility with grsec patches.
+* Add 'skip_optimus_dsm' module option so users of Lenovo T410s can use bbswitch
+  by setting this option to true.
+* Clarify license (GPLv3).
+
+Version 0.5 - 22 October 2012
+
+* Improved compatibility with older DKMS versions.
+* Set device state to D3cold instead of D3hot.
+* Only print DSM method call results when debugging is enabled.
+* Fixed runtime power management regression in Linux 3.6.
+
 Version 0.4.2 - 26 April 2012
 
 * Fixed a documentation error on unload_state.

README.md

@@ -22,6 +22,16 @@ detect the correct handle preceding _DSM and has some built-in safeguards:
   disabled again if that was the case before suspending. Hibernation should
   work, but it not tested.
 
+Precautionary measure : 
+- On some machines, turning off the card is permanent and the card does not
+  reappear on subsequents reboots, which can result into the screen staying
+  black all the time, including the BIOS screen.
+  If it occurs, first try to shutdown, unplug power cord, remove battery, wait
+  30s, then put everything back in and boot. If it's not solved, then the
+  solution is to reset the BIOS to factory settings. Before executing bbswitch
+  for the first time, it is therefore recommended to take note of the full key
+  sequence in the BIOS to do a reset. 
+
 Build
 -----
 
@@ -40,8 +50,8 @@ DKMS support
 
 If you have DKMS installed, you can install bbswitch in such a way that it
 survives kernel upgrades. It is recommended to remove older versions of bbswitch
-by running `dkms remove bbswitch/OLDVERSION --all` as root. To install the new
-version, simply run:
+by running `dkms remove -m bbswitch -v OLDVERSION --all` as root. To install
+the new version, simply run:
 
     # make -f Makefile.dkms
 
@@ -94,6 +104,10 @@ same behavior as:
 If not explictly set, the default behavior is not to change the power state of
 the discrete video card which equals to `load_state=-1 unload_state=-1`.
 
+The Lenovo T410 and Lenovo T410s laptops need the module option
+`skip_optimus_dsm=1`, otherwise it will detect the wrong methods which result in
+the card not being disabled.
+
 ### Disable card on boot
 
 These options can be useful to disable the card on boot time. Depending on your
@@ -103,10 +117,27 @@ get disabled on boot:
 
     bbswitch load_state=0
 
+Users of `kmod` should create `/etc/modprobe.d/bbswitch.conf` containing
+`options bbswitch load_state=0` to set the default options. To load the module,
+systemd users should create `/etc/modules-load.d/bbswitch.conf` containing
+`bbswitch`.
+
 You have to update your initial ramdisk (initrd) for the changes propagate to
 the boot process. On Debian and Ubuntu, this can performed by running
 `update-initramfs -u` as root.
 
+### Enable card on shutdown
+
+Some machines do not like the card being disabled at shutdown.  
+Add the next initscript (`/etc/init/bbswitch.conf`) :
+
+    description "Save power by disabling nvidia on Optimus"
+    author      "Lekensteyn <lekensteyn@gmail.com>"
+    start on    runlevel [2345]
+    stop on     runlevel [016]
+    pre-start   exec /sbin/modprobe bbswitch load_state=0 unload_state=1
+    pre-stop    exec /sbin/rmmod bbswitch 
+
 Reporting bugs
 --------------
 

bbswitch.c

@@ -9,18 +9,45 @@
  * Get status
  * # cat /proc/acpi/bbswitch
  */
+/*
+ *  Copyright (C) 2011-2013 Bumblebee Project
+ *  Author: Peter Wu <lekensteyn@gmail.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, either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  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, see <http://www.gnu.org/licenses/>.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include <linux/pci.h>
 #include <linux/acpi.h>
 #include <linux/module.h>
 #include <asm/uaccess.h>
 #include <linux/suspend.h>
 #include <linux/seq_file.h>
+#include <linux/pm_runtime.h>
+#include <linux/pm_domain.h>
+#include <linux/vga_switcheroo.h>
+#include <linux/version.h>
 
-#define BBSWITCH_VERSION "0.4.2"
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3,8,0)
+#   define ACPI_HANDLE DEVICE_ACPI_HANDLE
+#endif
+
+#define BBSWITCH_VERSION "0.8"
 
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Toggle the discrete graphics card");
-MODULE_AUTHOR("Peter Lekensteyn <lekensteyn@gmail.com>");
+MODULE_AUTHOR("Peter Wu <lekensteyn@gmail.com>");
 MODULE_VERSION(BBSWITCH_VERSION);
 
 enum {
@@ -35,6 +62,9 @@ module_param(load_state, int, 0400);
 static int unload_state = CARD_UNCHANGED;
 MODULE_PARM_DESC(unload_state, "Card state on unload (0 = off, 1 = on, -1 = unchanged)");
 module_param(unload_state, int, 0600);
+static bool skip_optimus_dsm = false;
+MODULE_PARM_DESC(skip_optimus_dsm, "Skip probe of Optimus discrete DSM (default = false)");
+module_param(skip_optimus_dsm, bool, 0400);
 
 extern struct proc_dir_entry *acpi_root_dir;
 
@@ -63,13 +93,15 @@ http://lxr.linux.no/#linux+v3.1.5/drivers/gpu/drm/i915/intel_acpi.c
 #define DSM_TYPE_NVIDIA         2
 static int dsm_type = DSM_TYPE_UNSUPPORTED;
 
+/* The cached name of the discrete device (of the form "0000:01:00.0"). */
+static char dis_dev_name[16];
+/* dis_dev is non-NULL iff it is currently bound by bbswitch (and off). */
 static struct pci_dev *dis_dev;
 static acpi_handle dis_handle;
 
-/* used for keeping the PM event handler */
-static struct notifier_block nb;
-/* whether the card was off before suspend or not; on: 0, off: 1 */
-int dis_before_suspend_disabled;
+/* The PM domain that wraps the PCI device, used to ensure that power is
+ * available before the device is put in D0. ("Nvidia" DSM and PR3). */
+static struct dev_pm_domain pm_domain;
 
 static char *buffer_to_string(const char *buffer, size_t n, char *target) {
     int i;
@@ -99,6 +131,9 @@ static int acpi_call_dsm(acpi_handle handle, const char muid[16], int revid,
     params[1].integer.value = revid;
     params[2].type = ACPI_TYPE_INTEGER;
     params[2].integer.value = func;
+    /* Although the ACPI spec defines Arg3 as a Package, in practise
+     * implementations expect a Buffer (CreateWordField and Index functions are
+     * applied to it). */
     params[3].type = ACPI_TYPE_BUFFER;
     params[3].buffer.length = 4;
     if (args) {
@@ -111,11 +146,14 @@ static int acpi_call_dsm(acpi_handle handle, const char muid[16], int revid,
 
     err = acpi_evaluate_object(handle, "_DSM", &input, &output);
     if (err) {
+        struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
         char muid_str[5 * 16];
         char args_str[5 * 4];
 
-        printk(KERN_WARNING "bbswitch: failed to evaluate _DSM {%s} 0x%X 0x%X"
-            " {%s}: %s\n",
+        acpi_get_name(handle, ACPI_FULL_PATHNAME, &buf);
+
+        pr_warn("failed to evaluate %s._DSM {%s} 0x%X 0x%X {%s}: %s\n",
+            (char *)buf.pointer,
             buffer_to_string(muid, 16, muid_str), revid, func,
             buffer_to_string(args,  4, args_str), acpi_format_exception(err));
         return err;
@@ -134,8 +172,8 @@ static int acpi_call_dsm(acpi_handle handle, const char muid[16], int revid,
             *result |= (obj->buffer.pointer[3] << 24);
         }
     } else {
-        printk(KERN_WARNING "bbswitch: _DSM call yields an unsupported result"
-            " type: %X\n", obj->type);
+        pr_warn("_DSM call yields an unsupported result type: %#x\n",
+            obj->type);
     }
 
     kfree(output.pointer);
@@ -165,8 +203,7 @@ static int bbswitch_optimus_dsm(void) {
             // failure
             return 1;
         }
-        printk(KERN_DEBUG "bbswitch: Result of Optimus _DSM call: %08X\n",
-            result);
+        pr_debug("Result of Optimus _DSM call: %08X\n", result);
     }
     return 0;
 }
@@ -181,8 +218,7 @@ static int bbswitch_acpi_off(void) {
             // failure
             return 1;
         }
-        printk(KERN_DEBUG "bbswitch: Result of _DSM call for OFF: %08X\n",
-            result);
+        pr_debug("Result of _DSM call for OFF: %08X\n", result);
     }
     return 0;
 }
@@ -197,69 +233,226 @@ static int bbswitch_acpi_on(void) {
             // failure
             return 1;
         }
-        printk(KERN_DEBUG "bbswitch: Result of _DSM call for ON: %08X\n",
-            result);
+        pr_debug("Result of _DSM call for ON: %08X\n", result);
     }
     return 0;
 }
 
 // Returns 1 if the card is disabled, 0 if enabled
 static int is_card_disabled(void) {
-    u32 cfg_word;
-    // read first config word which contains Vendor and Device ID. If all bits
-    // are enabled, the device is assumed to be off
-    pci_read_config_dword(dis_dev, 0, &cfg_word);
-    // if one of the bits is not enabled (the card is enabled), the inverted
-    // result will be non-zero and hence logical not will make it 0 ("false")
-    return !~cfg_word;
+    /* Assume that the device is disabled when our PCI driver found a device. */
+    return dis_dev != NULL;
 }
 
+
+/* Power source handling. */
+
+static int bbswitch_pmd_runtime_suspend(struct device *dev)
+{
+    int ret;
+
+    pr_debug("Preparing for runtime suspend.\n");
+
+    /* Put the device in D3. */
+    ret = dev->bus->pm->runtime_suspend(dev);
+    if (ret)
+        return ret;
+
+    bbswitch_acpi_off();
+    /* TODO For PR3, disable them. */
+    return 0;
+}
+
+static int bbswitch_pmd_runtime_resume(struct device *dev)
+{
+    pr_info("enabling discrete graphics\n");
+
+    bbswitch_acpi_on();
+    /* TODO For PR3, enable them. */
+
+    /* Now ensure that the device is actually put in D0 by PCI. */
+    return dev->bus->pm->runtime_resume(dev);
+}
+
+static void bbswitch_pmd_set(struct device *dev)
+{
+    pm_domain.ops = *dev->bus->pm;
+    pm_domain.ops.runtime_resume = bbswitch_pmd_runtime_resume;
+    pm_domain.ops.runtime_suspend = bbswitch_pmd_runtime_suspend;
+    dev_pm_domain_set(dev, &pm_domain);
+}
+
+
+/* Nvidia device itself. */
+
+static int bbswitch_pci_runtime_suspend(struct device *dev)
+{
+    struct pci_dev *pdev = to_pci_dev(dev);
+
+    pr_info("disabling discrete graphics\n");
+
+    /* Ensure that the audio driver knows not to touch us. */
+    vga_switcheroo_set_dynamic_switch(pdev, VGA_SWITCHEROO_OFF);
+
+    bbswitch_optimus_dsm();
+
+    /* Save state now that the device is still awake, makes PCI layer happy */
+    pci_save_state(pdev);
+    /* TODO if _PR3 is supported, should this be PCI_D3hot? */
+    pci_set_power_state(pdev, PCI_D3hot);
+    return 0;
+}
+
+static int bbswitch_pci_runtime_resume(struct device *dev)
+{
+    struct pci_dev *pdev = to_pci_dev(dev);
+
+    pr_debug("Finishing runtime resume.\n");
+
+    /* Resume audio driver. */
+    vga_switcheroo_set_dynamic_switch(pdev, VGA_SWITCHEROO_ON);
+    return 0;
+}
+
+static const struct dev_pm_ops bbswitch_pci_pm_ops = {
+    .runtime_suspend = bbswitch_pci_runtime_suspend,
+    .runtime_resume = bbswitch_pci_runtime_resume,
+    /* No runtime_idle callback, the default zero delay is sufficient. */
+};
+
+static int bbswitch_switcheroo_switchto(enum vga_switcheroo_client_id id)
+{
+    /* We do not support switching, only power on/off. */
+    return -ENOSYS;
+}
+
+static enum vga_switcheroo_client_id bbswitch_switcheroo_get_client_id(struct pci_dev *pdev)
+{
+    /* Our registered client is always the discrete GPU. */
+    return VGA_SWITCHEROO_DIS;
+}
+
+static const struct vga_switcheroo_handler bbswitch_handler = {
+    .switchto = bbswitch_switcheroo_switchto,
+    .get_client_id = bbswitch_switcheroo_get_client_id,
+};
+
+
+static void bbswitch_switcheroo_set_gpu_state(struct pci_dev *pdev, enum vga_switcheroo_state state)
+{
+    /* Nothing to do, we handle the PM domain ourselves. Perhaps we can add
+     * backwards compatibility with older kernels in this way and workaround
+     * bugs? */
+    pr_debug("set_gpu_state to %s\n", state == VGA_SWITCHEROO_ON ? "ON" : "OFF");
+}
+
+static bool bbswitch_switcheroo_can_switch(struct pci_dev *pdev)
+{
+    /* We do not support switching between IGD/DIS. */
+    return false;
+}
+
+static const struct vga_switcheroo_client_ops bbswitch_switcheroo_ops = {
+    .set_gpu_state = bbswitch_switcheroo_set_gpu_state,
+    .can_switch = bbswitch_switcheroo_can_switch,
+};
+
+static int bbswitch_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+    /* Only bind to the device which we discovered before. */
+    if (strcmp(dev_name(&pdev->dev), dis_dev_name))
+        return -ENODEV;
+
+    pr_debug("Found PCI device\n");
+    dis_dev = pdev;
+
+    bbswitch_pmd_set(&pdev->dev);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4,5,0)
+    vga_switcheroo_register_handler(&bbswitch_handler, 0);
+#else
+    vga_switcheroo_register_handler(&bbswitch_handler);
+#endif
+    vga_switcheroo_register_client(pdev, &bbswitch_switcheroo_ops, true);
+
+    /* Prevent kernel from detaching the PCI device for some devices that
+     * generate hotplug events. The graphics card is typically not physically
+     * removable. */
+    pci_ignore_hotplug(pdev);
+
+    pm_runtime_set_active(&pdev->dev); /* clear any errors */
+    /* Use autosuspend to avoid lspci waking up the device multiple times. */
+    pm_runtime_set_autosuspend_delay(&pdev->dev, 2000);
+    pm_runtime_use_autosuspend(&pdev->dev);
+    pm_runtime_allow(&pdev->dev);
+    pm_runtime_put_autosuspend(&pdev->dev);
+    return 0;
+}
+
+static void bbswitch_pci_remove(struct pci_dev *pdev)
+{
+    pr_debug("Removing PCI device\n");
+
+    pm_runtime_get_noresume(&pdev->dev);
+    pm_runtime_dont_use_autosuspend(&pdev->dev);
+    pm_runtime_forbid(&pdev->dev);
+
+    vga_switcheroo_unregister_client(pdev);
+    vga_switcheroo_unregister_handler();
+    dev_pm_domain_set(&pdev->dev, NULL);
+
+    dis_dev = NULL;
+}
+
+static const struct pci_device_id pciidlist[] = {
+    { PCI_DEVICE(PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID),
+      PCI_CLASS_DISPLAY_VGA << 8, 0xffff00 },
+    { PCI_DEVICE(PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID),
+      PCI_CLASS_DISPLAY_3D << 8, 0xffff00 },
+    { 0, 0, 0 },
+};
+
+static struct pci_driver bbswitch_pci_driver = {
+    .name = KBUILD_MODNAME,
+    .id_table = pciidlist,
+    .probe  = bbswitch_pci_probe,
+    .remove = bbswitch_pci_remove,
+    .driver.pm = &bbswitch_pci_pm_ops,
+};
+
+
 static void bbswitch_off(void) {
-    if (is_card_disabled())
+    int ret;
+
+    /* Do nothing if the device was disabled before. */
+    if (dis_dev)
         return;
 
-    // to prevent the system from possibly locking up, don't disable the device
-    // if it's still in use by a driver (i.e. nouveau or nvidia)
-    if (dis_dev->driver) {
-        printk(KERN_WARNING "bbswitch: device %s is in use by driver '%s', "
-            "refusing OFF\n", dev_name(&dis_dev->dev), dis_dev->driver->name);
+    ret = pci_register_driver(&bbswitch_pci_driver);
+    if (ret) {
+        pr_warn("Cannot register PCI device\n");
         return;
     }
 
-    printk(KERN_INFO "bbswitch: disabling discrete graphics\n");
+    /* If the probe failed, remove the driver such that it can be reprobed on
+     * the next registration. */
+    if (!dis_dev) {
+#if 0
+        /* TODO discover the other driver name if possible. */
+        pr_warn("device %s is in use by driver '%s', refusing OFF\n",
+            dev_name(&dis_dev->dev), dis_dev->driver->name);
+#endif
 
-    if (bbswitch_optimus_dsm()) {
-        printk(KERN_WARNING "bbswitch: Optimus ACPI call failed, the device is"
-            " not disabled\n");
-        return;
+        pr_warn("Could not bind to device, is it in use by an other driver?\n");
+        pci_unregister_driver(&bbswitch_pci_driver);
     }
-
-    pci_save_state(dis_dev);
-    pci_clear_master(dis_dev);
-    pci_disable_device(dis_dev);
-    pci_set_power_state(dis_dev, PCI_D3hot);
-
-    if (bbswitch_acpi_off())
-        printk(KERN_WARNING "bbswitch: The discrete card could not be disabled"
-                " by a _DSM call\n");
 }
 
 static void bbswitch_on(void) {
-    if (!is_card_disabled())
+    /* Do nothing if no device exists that was previously disabled. */
+    if (!dis_dev)
         return;
 
-    printk(KERN_INFO "bbswitch: enabling discrete graphics\n");
-
-    if (bbswitch_acpi_on())
-        printk(KERN_WARNING "bbswitch: The discrete card could not be enabled"
-            " by a _DSM call\n");
-
-    pci_set_power_state(dis_dev, PCI_D0);
-    pci_restore_state(dis_dev);
-    if (pci_enable_device(dis_dev))
-        printk(KERN_WARNING "bbswitch: failed to enable %s\n",
-            dev_name(&dis_dev->dev));
-    pci_set_master(dis_dev);
+    pci_unregister_driver(&bbswitch_pci_driver);
 }
 
 static ssize_t bbswitch_proc_write(struct file *fp, const char __user *buff,
@@ -283,7 +476,7 @@ static ssize_t bbswitch_proc_write(struct file *fp, const char __user *buff,
 
 static int bbswitch_proc_show(struct seq_file *seqfp, void *p) {
     // show the card state. Example output: 0000:01:00:00 ON
-    seq_printf(seqfp, "%s %s\n", dev_name(&dis_dev->dev),
+    seq_printf(seqfp, "%s %s\n", dis_dev_name,
              is_card_disabled() ? "OFF" : "ON");
     return 0;
 }
@@ -291,34 +484,6 @@ static int bbswitch_proc_open(struct inode *inode, struct file *file) {
     return single_open(file, bbswitch_proc_show, NULL);
 }
 
-static int bbswitch_pm_handler(struct notifier_block *nbp,
-    unsigned long event_type, void *p) {
-    switch (event_type) {
-    case PM_HIBERNATION_PREPARE:
-    case PM_SUSPEND_PREPARE:
-        dis_before_suspend_disabled = is_card_disabled();
-        // enable the device before suspend to avoid the PCI config space from
-        // being saved incorrectly
-        if (dis_before_suspend_disabled)
-            bbswitch_on();
-        break;
-    case PM_POST_HIBERNATION:
-    case PM_POST_SUSPEND:
-    case PM_POST_RESTORE:
-        // after suspend, the card is on, but if it was off before suspend,
-        // disable it again
-        if (dis_before_suspend_disabled)
-            bbswitch_off();
-        break;
-    case PM_RESTORE_PREPARE:
-        // deliberately don't do anything as it does not occur before suspend
-        // nor hibernate, but before restoring a saved image. In that case,
-        // either PM_POST_HIBERNATION or PM_POST_RESTORE will be called
-        break;
-    }
-    return 0;
-}
-
 static struct file_operations bbswitch_fops = {
     .open   = bbswitch_proc_open,
     .read   = seq_read,
@@ -332,7 +497,7 @@ static int __init bbswitch_init(void) {
     struct pci_dev *pdev = NULL;
     acpi_handle igd_handle = NULL;
 
-    printk(KERN_INFO "bbswitch: version %s\n", BBSWITCH_VERSION);
+    pr_info("version %s\n", BBSWITCH_VERSION);
 
     while ((pdev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, pdev)) != NULL) {
         struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
@@ -343,10 +508,10 @@ static int __init bbswitch_init(void) {
             pci_class != PCI_CLASS_DISPLAY_3D)
             continue;
 
-        handle = DEVICE_ACPI_HANDLE(&pdev->dev);
+        handle = ACPI_HANDLE(&pdev->dev);
         if (!handle) {
-            printk(KERN_WARNING "bbswitch: cannot find ACPI handle for VGA"
-                " device %s\n", dev_name(&pdev->dev));
+            pr_warn("cannot find ACPI handle for VGA device %s\n",
+                dev_name(&pdev->dev));
             continue;
         }
 
@@ -354,58 +519,54 @@ static int __init bbswitch_init(void) {
 
         if (pdev->vendor == PCI_VENDOR_ID_INTEL) {
             igd_handle = handle;
-            printk(KERN_INFO "bbswitch: Found integrated VGA device %s: %s\n",
+            pr_info("Found integrated VGA device %s: %s\n",
                 dev_name(&pdev->dev), (char *)buf.pointer);
         } else {
-            dis_dev = pdev;
+            strlcpy(dis_dev_name, dev_name(&pdev->dev), sizeof(dis_dev_name));
             dis_handle = handle;
-            printk(KERN_INFO "bbswitch: Found discrete VGA device %s: %s\n",
+            pr_info("Found discrete VGA device %s: %s\n",
                 dev_name(&pdev->dev), (char *)buf.pointer);
         }
         kfree(buf.pointer);
     }
 
-    if (dis_dev == NULL) {
-        printk(KERN_ERR "bbswitch: No discrete VGA device found\n");
+    if (dis_handle == NULL) {
+        pr_err("No discrete VGA device found\n");
         return -ENODEV;
     }
 
-    if (has_dsm_func(acpi_optimus_dsm_muid, 0x100, 0x1A)) {
+    if (!skip_optimus_dsm &&
+            has_dsm_func(acpi_optimus_dsm_muid, 0x100, 0x1A)) {
         dsm_type = DSM_TYPE_OPTIMUS;
-        printk(KERN_INFO "bbswitch: detected an Optimus _DSM function\n");
+        pr_info("detected an Optimus _DSM function\n");
     } else if (has_dsm_func(acpi_nvidia_dsm_muid, 0x102, 0x3)) {
         dsm_type = DSM_TYPE_NVIDIA;
-        printk(KERN_INFO "bbswitch: detected a nVidia _DSM function\n");
+        pr_info("detected a nVidia _DSM function\n");
     } else {
        /* At least two Acer machines are known to use the intel ACPI handle
         * with the legacy nvidia DSM */
         dis_handle = igd_handle;
-        if (has_dsm_func(acpi_nvidia_dsm_muid, 0x102, 0x3)) {
+        if (dis_handle && has_dsm_func(acpi_nvidia_dsm_muid, 0x102, 0x3)) {
             dsm_type = DSM_TYPE_NVIDIA;
-            printk(KERN_INFO "bbswitch: detected a nVidia _DSM function on the"
+            pr_info("detected a nVidia _DSM function on the"
                 " integrated video card\n");
         } else {
-            printk(KERN_ERR "bbswitch: No suitable _DSM call found.\n");
+            pr_err("No suitable _DSM call found.\n");
             return -ENODEV;
         }
     }
 
     acpi_entry = proc_create("bbswitch", 0664, acpi_root_dir, &bbswitch_fops);
     if (acpi_entry == NULL) {
-        printk(KERN_ERR "bbswitch: Couldn't create proc entry\n");
+        pr_err("Couldn't create proc entry\n");
         return -ENOMEM;
     }
 
-    if (load_state == CARD_ON)
-        bbswitch_on();
-    else if (load_state == CARD_OFF)
+    if (load_state == CARD_OFF)
         bbswitch_off();
 
-    printk(KERN_INFO "bbswitch: Succesfully loaded. Discrete card %s is %s\n",
-        dev_name(&dis_dev->dev), is_card_disabled() ? "off" : "on");
-
-    nb.notifier_call = &bbswitch_pm_handler;
-    register_pm_notifier(&nb);
+    pr_info("Succesfully loaded. Discrete card %s is %s\n",
+        dis_dev_name, is_card_disabled() ? "off" : "on");
 
     return 0;
 }
@@ -413,17 +574,11 @@ static int __init bbswitch_init(void) {
 static void __exit bbswitch_exit(void) {
     remove_proc_entry("bbswitch", acpi_root_dir);
 
-    if (unload_state == CARD_ON)
-        bbswitch_on();
-    else if (unload_state == CARD_OFF)
-        bbswitch_off();
-
-    printk(KERN_INFO "bbswitch: Unloaded. Discrete card %s is %s\n",
-        dev_name(&dis_dev->dev), is_card_disabled() ? "off" : "on");
-
-    if (nb.notifier_call)
-        unregister_pm_notifier(&nb);
+    bbswitch_on();
+    pr_info("Unloaded\n");
 }
 
 module_init(bbswitch_init);
 module_exit(bbswitch_exit);
+
+/* vim: set sw=4 ts=4 et: */