The only difference between acpi_bus_scan() and acpi_bus_add() is the
invocation of acpi_update_all_gpes() in the latter which in fact is
unnecessary, because acpi_update_all_gpes() has already been called
by acpi_scan_init() and the way it is implemented guarantees the next
invocations of it to do nothing.

For this reason, drop acpi_bus_add() and make all its callers use
acpi_bus_scan() directly instead of it.  Additionally, rearrange the
code in acpi_scan_init() slightly to improve the visibility of the
acpi_update_all_gpes() call in there.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>

Should use acpi_device pointer directly instead of use handle and
get the device pointer again later.
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

All callers of acpi_bus_trim() pass 1 (true) as the second argument
of it, so remove that argument entirely and change acpi_bus_trim()
to always behave as though it were 1.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

The ops field in struct acpi_device is not used anywhere, so remove
it.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NToshi Kani <toshi.kani@hp.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

With commit f2a33cde55a03 "ACPI: Drop ACPI device .bind() and .unbind()
callbacks", acpi_op_bind and acpi_op_unbind are not used any more. So
remove them.
Signed-off-by: NJiang Liu <jiang.liu@huawei.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

This member is never initialized and never referenced, so remove it.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Drop the .bind() and .unbind() that have no more users from
struct acpi_device_ops and remove all of the code referring to
them from drivers/acpi/scan.c.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NToshi Kani <toshi.kani@hp.com>

Add two new callbacks,.setup() and .cleanup(), struct acpi_bus_type
and modify acpi_platform_notify() to call .setup() after executing
acpi_bind_one() successfully and acpi_platform_notify_remove() to
call .cleanup() before running acpi_unbind_one().  This will allow
the users of struct acpi_bus_type, PCI in particular, to specify
operations to be executed right after the given device has been
associated with a companion struct acpi_device and right before
it's going to be detached from that companion, respectively.

The main motivation is to be able to get rid of acpi_pci_bind()
and acpi_pci_unbind(), which are horrible horrible stuff.  [In short,
there are three problems with them: The way they populate the .bind()
and .unbind() callbacks of ACPI devices is rather less than
straightforward, they require special hotplug-specific paths to be
present in the ACPI namespace scanning code and by the time
acpi_pci_unbind() is called the PCI device object in question may
not exist any more.]
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NToshi Kani <toshi.kani@hp.com>

The callers of acpi_bus_add() usually assume that if it has
succeeded, then a struct acpi_device object has been attached to
the handle passed as the first argument.  Unfortunately, however,
this assumption is wrong, because acpi_bus_scan(), and acpi_bus_add()
too as a result, may return a pointer to a different struct
acpi_device object on success (it may be an object corresponding to
one of the descendant ACPI nodes in the namespace scope below that
handle).

For this reason, the callers of acpi_bus_add() who care about
whether or not a struct acpi_device object has been created for
its first argument need to check that using acpi_bus_get_device()
anyway, so the second argument of acpi_bus_add() is not really
useful for them.  The same observation applies to acpi_bus_scan()
executed directly from acpi_scan_init().

Therefore modify the relevant callers of acpi_bus_add() to check the
existence of the struct acpi_device in question with the help of
acpi_bus_get_device() and drop the no longer necessary second
argument of acpi_bus_add().  Accordingly, modify acpi_scan_init() to
use acpi_bus_get_device() to get acpi_root and drop the no longer
needed second argument of acpi_bus_scan().
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NToshi Kani <toshi.kani@hp.com>

After the removal of the second argument of acpi_bus_scan() there is
no difference between the ACPI_BUS_ADD_MATCH and ACPI_BUS_ADD_START
add types, so the add_type field in struct acpi_device may be
replaced with a single flag.  Do that calling the flag match_driver.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NToshi Kani <toshi.kani@hp.com>

Notice that acpi_bus_add() uses only 2 of its 4 arguments and
redefine its header to match the body.  Update all of its callers as
necessary and observe that this leads to quite a number of removed
lines of code (Linus will like that).

Add a kerneldoc comment documenting acpi_bus_add() and wonder how
its callers make wrong assumptions about the second argument (make
note to self to take care of that later).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NToshi Kani <toshi.kani@hp.com>

The ACPI PCI root bridge driver was the only ACPI driver implementing
the .start() callback, which isn't used by any ACPI drivers any more
now.

For this reason, acpi_start_single_object() has no purpose any more,
so remove it and all references to it.  Also remove
acpi_bus_start_device(), whose only purpose was to call
acpi_start_single_object().

Moreover, since after the removal of acpi_bus_start_device() the
only purpose of acpi_bus_start() remains to call
acpi_update_all_gpes(), move that into acpi_bus_add() and drop
acpi_bus_start() too, remove its header from acpi_bus.h and
update all of its former users accordingly.

This change was previously proposed in a different from by
Yinghai Lu.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NToshi Kani <toshi.kani@hp.com>

Notice that one member of struct acpi_bus_ops, acpi_op_add, is not
used anywhere any more and the relationship between its remaining
members, acpi_op_match and acpi_op_start, is such that it doesn't
make sense to set the latter without setting the former at the same
time.  Therefore, replace struct acpi_bus_ops with new a enum type,
enum acpi_bus_add_type, with three values, ACPI_BUS_ADD_BASIC,
ACPI_BUS_ADD_MATCH, ACPI_BUS_ADD_START, corresponding to
both acpi_op_match and acpi_op_start unset, acpi_op_match set and
acpi_op_start unset, and both acpi_op_match and acpi_op_start set,
respectively.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NToshi Kani <toshi.kani@hp.com>

Split the ACPI namespace scanning for devices into two passes, such
that struct acpi_device objects are registerd in the first pass
without probing ACPI drivers and the drivers are probed against them
directly in the second pass.

There are two main reasons for doing that.

First, the ACPI PCI root bridge driver's .add() routine,
acpi_pci_root_add(), causes struct pci_dev objects to be created for
all PCI devices under the given root bridge.  Usually, there are
corresponding ACPI device nodes in the ACPI namespace for some of
those devices and therefore there should be "companion" struct
acpi_device objects to attach those struct pci_dev objects to.  These
struct acpi_device objects should exist when the corresponding
struct pci_dev objects are created, but that is only guaranteed
during boot and not during hotplug.  This leads to a number of
functional differences between the boot and the hotplug cases which
are not strictly necessary and make the code more complicated.

For example, this forces the ACPI PCI root bridge driver to defer the
registration of the just created struct pci_dev objects and to use a
special .start() callback routine, acpi_pci_root_start(), to make
sure that all of the "companion" struct acpi_device objects will be
present at PCI devices registration time during hotplug.

If those differences can be eliminated, we will be able to
consolidate the boot and hotplug code paths for the enumeration and
registration of PCI devices and to reduce the complexity of that
code quite a bit.

The second reason is that, in general, it should be possible to
resolve conflicts of resources assigned by the BIOS to different
devices represented by ACPI namespace nodes before any drivers bind
to them and before they are attached to "companion" objects
representing physical devices (such as struct pci_dev).  However, for
this purpose we first need to enumerate all ACPI device nodes in the
given namespace scope.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
Acked-by: NToshi Kani <toshi.kani@hp.com>

Currently we have valid flag to represent if this ACPI device power
state is valid. A device power state is valid does not necessarily
mean we, as OSPM, has a mean to put the device into that power state,
e.g. D3 cold is always a valid power state for any ACPI device, but if
there is no _PS3 or _PRx for this device, we can't really put that
device into D3 cold power state. The same is true for D0 power state.

So here comes the os_accessible flag, which is only set if the device
has provided us the required means to put it into that power state,
e.g. if we have _PS3 or _PRx, we can put the device into D3 cold state
and thus, D3 cold power state's os_accessible flag will be set in this
case.

And a new wrapper inline function is added to be used to check if
firmware has provided us a way to power off the device during runtime.
Signed-off-by: NAaron Lu <aaron.lu@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

To avoid adding an ACPI handle pointer to struct device on
architectures that don't use ACPI, or generally when CONFIG_ACPI is
not set, in which cases that pointer is useless, define struct
acpi_dev_node that will contain the handle pointer if CONFIG_ACPI is
set and will be empty otherwise and use it to represent the ACPI
device node field in struct device.

In addition to that define macros for reading and setting the ACPI
handle of a device that don't generate code when CONFIG_ACPI is
unset.  Modify the ACPI subsystem to use those macros instead of
referring to the given device's ACPI handle directly.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

_SUN method provides the slot unique-ID in the ACPI namespace. And The value
is written in Advanced Configuration and Power Interface Specification as
follows:

"The _SUN value is required to be unique among the slots ofthe same type.
It is also recommended that this number match the slot number printed on
the physical slot whenever possible."

So if we can know the value, we can identify the physical position of the
slot in the system.

The patch creates "sun" file in sysfs for identifying physical position
of the slot.
Signed-off-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Reviewed-by: NToshi Kani <toshi.kani@hp.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Version 20121018.
Signed-off-by: NBob Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Now calls _SUB in addition to the other ID methods: _HID, _CID,
and _UID.
Signed-off-by: NBob Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Fixes some problems introduced by late changes to the table as it
was added to the ACPI 5.0 specification.  Both the table compiler
and the disassembler and the main header support for the table.
Signed-off-by: NBob Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Resolves to a 32-bit move for the normal case, strncpy on machines
that do not support misaligned transfers.
Signed-off-by: NBob Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

For consistency with the rest of the source code.
Signed-off-by: NBob Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

This makes all comments consistent.
Signed-off-by: NBob Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Maintenance for source code consistency.
Signed-off-by: NBob Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

New version of "indent" program will generate different outputs that
will lead to the divergences between the Linux and the ACPICA.
This patch fixes such divergences caused by the "indent" program.
The version of the "indent" used for this patch is "GNU indent 2.2.11".

This patch will not affect the generated vmlinux binary.
This will decrease 581 lines of 20120913 divergence.diff.
Signed-off-by: NRobert Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

There are definitions that can been converted into new styles by
the recent AcpiSrc while they remain the old styles in the Linux.
This patch fixes those definitions that will be converted by the
AcpiSrc.

This patch will not affect the generated vmlinux binary.
This will decrease 97 lines of 20120913 divergence.diff.
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

There are conflicts in the "acpi_device_id*" definitions between the
Linux and the ACPICA.  The definitions of acpi_device_id* in ACPICA
have been changed to the "acpi_pnp_device_id*".  This patch changes
the corresponding "acpica_device_id*" definitiions in the Linux.

This patch will not affect the generated vmlinx binary.
This will decrease 298 lines of 20120913 divergence.diff.
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Debugger improvements in ACPICA are always ignored by ACPICA Linux
release.  This will lead to divergences between Linux and ACPICA.
This patch fixes such unmerged debugger updates.

Following patches are included:
1. Fixed a couple compiler warnings for extra extern
   Wed, 14 Mar 2007 21:12:19 +0000
2. Cleanup for internal Reference Object.
   Wed, 27 Aug 2008 10:11:30 -0700
3. Debugger: Lock method args for multithread command.
   Fri, 24 Apr 2009 12:28:49 -0700
4. Debugger: Add max count argument for Batch command.
   Tue, 29 Sep 2009 12:31:58 -0700
5. Add new host interfaces for _OSI support.
   Thu, 5 Aug 2010 14:18:28 -0700
6. Increase debugger buffer size for method return objects.
   Wed, 17 Nov 2010 13:48:30 -0800
7. Debugger: Add command to display status of global handlers.
   Tue, 25 Jan 2011 13:47:58 -0800
8. Debugger: Split large dbcmds.c file.
   Wed, 26 Jan 2011 13:03:41 -0800
9. Debugger/AcpiExec: Add support to pass complex args to methods.
   Tue, 17 May 2011 13:33:39 -0700
10.Debugger: Add Template command to dump resource templates.
   Fri, 28 Oct 2011 14:18:51 -0700
11.Support for custom ACPICA build for ACPI 5.0 reduced hardware.
   Wed, 1 Feb 2012 13:18:17 -0800
12.Debugger: Improve command help support.
   Wed, 15 Feb 2012 07:59:26 -0800
13.Update ACPI_HW_DEPENDENT* macro invocations.
   Wed, 15 Feb 2012 08:14:08 -0800
14.Debugger: Rename function to simplify source code conversion.
   Wed, 13 Jun 2012 14:23:06 -0700
15.Debugger: Enhance "Tables" and "Unload" commands.
   Fri, 29 Jun 2012 13:10:58 -0700
16.Debugger: update prototype for AcpiDbSleep function.
   Fri, 17 Aug 2012 13:43:02 -0700

This patch will not affect the generated vmlinx binary.
This will decrease 264 lines of 20120913 divergence.diff.
Signed-off-by: NRobert Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

With ACPI 5 we are starting to see devices that don't natively support
discovery but can be enumerated with the help of the ACPI namespace.
Typically, these devices can be represented in the Linux device driver
model as platform devices or some serial bus devices, like SPI or I2C
devices.

Since we want to re-use existing drivers for those devices, we need a
way for drivers to specify the ACPI IDs of supported devices, so that
they can be matched against device nodes in the ACPI namespace.  To
this end, it is sufficient to add a pointer to an array of supported
ACPI device IDs, that can be provided by the driver, to struct device.

Moreover, things like ACPI power management need to have access to
the ACPI handle of each supported device, because that handle is used
to invoke AML methods associated with the corresponding ACPI device
node.  The ACPI handles of devices are now stored in the archdata
member structure of struct device whose definition depends on the
architecture and includes the ACPI handle only on x86 and ia64. Since
the pointer to an array of supported ACPI IDs is added to struct
device_driver in an architecture-independent way, it is logical to
move the ACPI handle from archdata to struct device itself at the same
time.  This also makes code more straightforward in some places and
follows the example of Device Trees that have a poiter to struct
device_node in there too.

This changeset is based on Mika Westerberg's work.
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Acked-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Removed lockable in struct acpi_device_flags since it is no
longer used by any code. acpi_bus_hot_remove_device() cannot
use this flag because acpi_bus_trim() frees up its acpi_device
object. Furthermore, the dock driver calls _LCK method without
using this lockable flag.
Signed-off-by: NToshi Kani <toshi.kani@hp.com>
Reviewed-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Commit b87b49cd0efd ("ACPI / PM: Move device PM functions related to sleep
states") declared acpi_target_system_state() for CONFIG_PM_SLEEP whereas
it is only defined for CONFIG_ACPI_SLEEP, resulting in the following link
error:

drivers/built-in.o: In function `acpi_pm_device_sleep_wake':
drivers/acpi/device_pm.c:342: undefined reference to `acpi_target_system_state'
drivers/built-in.o: In function `acpi_dev_suspend_late':
drivers/acpi/device_pm.c:501: undefined reference to `acpi_target_system_state'
drivers/built-in.o: In function `acpi_pm_device_sleep_state':
drivers/acpi/device_pm.c:221: undefined reference to `acpi_target_system_state'

Define it only for CONFIG_ACPI_SLEEP and fallback to a dummy definition
for other configs.

[rjw: The problem only occurs for exotic .configs in which
 HIBERNATE_CALLBACKS is selected by XEN_SAVE_RESTORE and neither
 SUSPEND nor HIBERNATION is set.]
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Introduce helper function returning the target sleep state of the
system and use it to move the remaining device power management
functions from sleep.c to device_pm.c.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

If the caller of acpi_bus_set_power() already has a pointer to the
struct acpi_device object corresponding to the device in question, it
doesn't make sense for it to go through acpi_bus_get_device(), which
may be costly, because it involves acquiring the global ACPI
namespace mutex.

For this reason, export the function operating on struct acpi_device
objects used internally by acpi_bus_set_power(), so that it may be
called instead of acpi_bus_set_power() in the above case, and change
its name to acpi_device_set_power().

Additionally, introduce two inline wrappers for checking ACPI PM
capabilities of devices represented by struct acpi_device objects.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Two device wakeup management routines in device_pm.c and sleep.c,
acpi_pm_device_run_wake() and acpi_pm_device_sleep_wake(), take a
device pointer argument and use it to obtain the ACPI handle of the
corresponding ACPI namespace node.  That handle is then used to get
the address of the struct acpi_device object corresponding to the
struct device passed as the argument.

Unfortunately, that last operation may be costly, because it involves
taking the global ACPI namespace mutex, so it shouldn't be carried
out too often.  However, the callers of those routines usually call
them in a row with acpi_pm_device_sleep_state() which also takes that
mutex for the same reason, so it would be more efficient if they ran
acpi_bus_get_device() themselves to obtain a pointer to the struct
acpi_device object in question and then passed that pointer to the
appropriate PM routines.

To make that possible, split each of the PM routines mentioned above
in two parts, one taking a struct acpi_device pointer argument and
the other implementing the current interface for compatibility.

Additionally, change acpi_pm_device_run_wake() to actually return
an error code if there is an error while setting up runtime remote
wakeup for the device.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The ACPI function for choosing device power state is now located
in drivers/acpi/sleep.c, but drivers/acpi/device_pm.c is a more
logical place for it, so move it there.

However, instead of moving the function entirely, move its core only
under a different name and with a different list of arguments, so
that it is more flexible, and leave a wrapper around it in the
original location.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

ACPI routines for adding and removing device wakeup notifiers are
currently defined in a PCI-specific file, but they will be necessary
for non-PCI devices too, so move them to a separate file under
drivers/acpi and rename them to indicate their ACPI origins.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The kerneldoc comments for acpi_pm_device_sleep_state(),
acpi_pm_device_run_wake(), and acpi_pm_device_sleep_wake() are
outdated or otherwise inaccurate and/or don't follow the common
kerneldoc patterns, so fix them.

Additionally, notice that acpi_pm_device_run_wake() should be under
CONFIG_PM_RUNTIME rather than under CONFIG_PM_SLEEP, so fix that too.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

This effectively reverts 859a3f86 ("ACPI: simplify
acpi_pci_irq_add_prt() API") and d9efae36 ("ACPI: simplify
acpi_pci_irq_del_prt() API").

The reason is to disentangle these routines from the struct pci_bus.
We want to be able to add the _PRT before the struct pci_bus
exists, and delete the _PRT after we've removed the pci_bus.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NTaku Izumi <izumi.taku@jp.fujitsu.com>

Add support to export the device description obtained from the ACPI _STR
method, if one exists for a device, to user-space via a sysfs interface.
This new interface provides a standard and platform neutral way for users
to obtain the description text stored in the ACPI _STR method.  If no
_STR method exists for the device, no sysfs 'description' file will be
created.  The 'description' file will be located in the /sys/devices/
directory using the device's path.

/sys/device/<bus>/<bridge path>/<device path>.../firmware_node/description

Example:

/sys/devices/pci0000:00/0000:00.07.0/0000:0e:00.0/firmware_node/description

It can also be located using the ACPI device path, for example:

/sys/devices/LNXSYSTM:00/device:00/ACPI0004:00/PNP0A08:00/device:13/device:15/description
/sys/devices/LNXSYSTM:00/device:00/ACPI0004:00/ACPI0004:01/ACPI0007:02/description

Execute the 'cat' command on the 'description' file to obtain the
description string for that device.

This patch also includes documentation describing how the new sysfs
interface works

Changes from v1-v2 based on comments by Len Brown and Fengguang Wu
* Removed output "No Description" and leaving a NULL attribute if the
_STR method failed to evaluate.

* In acpi_device_remove_files() removed the redundent check of
dev->pnp.str_obj before calling free.  This check triggered a message
from smatch.
Signed-off-by: NLance Ortiz <lance.ortiz@hp.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

Convert #include "..." to #include <path/...> in kernel system headers.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: NDave Jones <davej@redhat.com>