- Introduce fwnode operations for all of the separate types of
"firmware nodes" that can be handled by the device properties
framework and drop the type field from struct fwnode_handle
(Sakari Ailus, Arnd Bergmann).
- Make the device properties framework use const fwnode arguments
where possible (Sakari Ailus).
- Add a helper for the consolidated handling of node references
to the device properties framework (Sakari Ailus).
- Switch over the ACPI part of the device properties framework
to the new UUID API (Andy Shevchenko).
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Merge tag 'devprop-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull device properties framework updates from Rafael Wysocki:
"These introduce fwnode operations for all of the separate types of
'firmware nodes' that can be handled by the device properties
framework, make the framework use const fwnode arguments all over, add
a helper for the consolidated handling of node references and switch
over the framework to the new UUID API.
Specifics:
- Introduce fwnode operations for all of the separate types of
'firmware nodes' that can be handled by the device properties
framework and drop the type field from struct fwnode_handle (Sakari
Ailus, Arnd Bergmann).
- Make the device properties framework use const fwnode arguments
where possible (Sakari Ailus).
- Add a helper for the consolidated handling of node references to
the device properties framework (Sakari Ailus).
- Switch over the ACPI part of the device properties framework to the
new UUID API (Andy Shevchenko)"
* tag 'devprop-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
ACPI: device property: Switch to use new generic UUID API
device property: export irqchip_fwnode_ops
device property: Introduce fwnode_property_get_reference_args
device property: Constify fwnode property API
device property: Constify argument to pset fwnode backend
ACPI: Constify internal fwnode arguments
ACPI: Constify acpi_bus helper functions, switch to macros
ACPI: Prepare for constifying acpi_get_next_subnode() fwnode argument
device property: Get rid of struct fwnode_handle type field
ACPI: Use IS_ERR_OR_NULL() instead of non-NULL check in is_acpi_data_node()
acpi_graph_get_child_prop_value() is intended to find a child node with a
certain property value pair. The check
if (!fwnode_property_read_u32(fwnode, prop_name, &nr))
continue;
is faulty: fwnode_property_read_u32() returns zero on success, not on
failure, leading to comparing values only if the searched property was not
found.
Moreover, the check is made against the parent device node instead of
the child one as it should be.
Fixes: 79389a83bc (ACPI / property: Add support for remote endpoints)
Reported-by: Hyungwoo Yang <hyungwoo.yang@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: 4.12+ <stable@vger.kernel.org> # 4.12+
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
While the rest of the world has standardized on _DSD as the way to store
device properties in AML (introduced with ACPI 5.1 in 2014), Apple has
been using a custom _DSM to achieve the same for much longer (ever since
they switched from DeviceTree-based PowerPC to Intel in 2005, verified
with MacOS X 10.4.11).
The theory of operation on macOS is as follows: AppleACPIPlatform.kext
invokes mergeEFIproperties() and mergeDSMproperties() for each device to
merge properties conveyed by EFI drivers as well as properties stored in
AML into the I/O Kit registry from which they can be retrieved by
drivers. We've been supporting EFI properties since commit 58c5475aba
("x86/efi: Retrieve and assign Apple device properties"). The present
commit adds support for _DSM properties, thereby completing our support
for Apple device properties. The _DSM properties are made available
under the primary fwnode, the EFI properties under the secondary fwnode.
So for devices which possess both property types, they can all be
elegantly accessed with the uniform API in <linux/property.h>.
Until recently we had no need to support _DSM properties, they contained
only uninteresting garbage. The situation has changed with MacBooks and
MacBook Pros introduced since 2015: Their keyboard is attached with SPI
instead of USB and the _CRS data which is necessary to initialize the
spi driver only contains valid information if OSPM responds "false" to
_OSI("Darwin"). If OSPM responds "true", _CRS is empty and the spi
driver fails to initialize. The rationale is very simple, Apple only
cares about macOS and Windows: On Windows, _CRS contains valid data,
whereas on macOS it is empty. Instead, macOS gleans the necessary data
from the _DSM properties.
Since Linux deliberately defaults to responding "true" to _OSI("Darwin"),
we need to emulate macOS' behaviour by initializing the spi driver with
data returned by the _DSM.
An out-of-tree driver for the SPI keyboard exists which currently binds
to the ACPI device, invokes the _DSM, parses the returned package and
instantiates an SPI device with the data gleaned from the _DSM:
https://github.com/cb22/macbook12-spi-driver/commit/9a416d699ef4https://github.com/cb22/macbook12-spi-driver/commit/0c34936ed9a1
By adding support for Apple's _DSM properties in generic ACPI code, the
out-of-tree driver will be able to register as a regular SPI driver,
significantly reducing its amount of code and improving its chances to
be mainlined.
The SPI keyboard will not be the only user of this commit: E.g. on the
MacBook8,1, the UART-attached Bluetooth device likewise returns empty
_CRS data if OSPM returns "true" to _OSI("Darwin").
The _DSM returns a Package whose format unfortunately deviates slightly
from the _DSD spec: The properties are marshalled up in a single Package
as alternating key/value elements, unlike _DSD which stores them as a
Package of 2-element Packages. The present commit therefore converts
the Package to _DSD format and the ACPI core can then treat the data as
if Apple would follow the standard.
Well, except for one small annoyance: The properties returned by the
_DSM only ever have one of two types, Integer or Buffer. The former is
retrievable as usual with device_property_read_u64(), but the latter is
not part of the _DSD spec and it is not possible to retrieve Buffer
properties with the device_property_read_*() functions due to the type
checking performed in drivers/acpi/property.c. It is however possible
to retrieve them with acpi_dev_get_property(). Apple is using the
Buffer type somewhat sloppily to store null-terminated strings but also
integers. The real data type is not distinguishable by the ACPI core
and the onus is on the caller to use the contents of the Buffer in an
appropriate way.
In case Apple moves to _DSD in the future, this commit first checks for
_DSD and falls back to _DSM only if _DSD is not found.
Tested-by: Ronald Tschalär <ronald@innovation.ch>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Fabricated devices such as LNXPWRBN lack a handle, causing evaluation
of _CCA and _DSD to always fail with AE_BAD_PARAMETER. While that is
merely a (negligible) waste of processing power, evaluating a _DSM for
them (such as Apple's device properties _DSM which we're about to add)
results in an ugly error:
ACPI: \: failed to evaluate _DSM (0x1001)
Avoid by not evaluating _DSD and the upcoming _DSM for devices without
handle.
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
There are new types and helpers that are supposed to be used in new code.
As a preparation to get rid of legacy types and API functions do
the conversion here.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The new fwnode_property_get_reference_args() interface amends the fwnode
property API with the functionality of both of_parse_phandle_with_args()
and __acpi_node_get_property_reference().
The semantics is slightly different: the cells property is ignored on ACPI
as the number of arguments can be explicitly obtained from the firmware
interface.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Make fwnode arguments to the fwnode property API const.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Constify internal ACPI fwnode arguments in preparation for the same in
fwnode API.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Make local variables const (head) or add new variables; adev was used for
two purposes: to refer the root device node and its children. The two
purposes are separated by this patch.
This is preparation for making fwnode arguments const for fwnode ops.
Don't constify the argument itself quite yet as this is used as a callback
function.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Instead of relying on the struct fwnode_handle type field, define
fwnode_operations structs for all separate types of fwnodes. To find out
the type, compare to the ops field to relevant ops structs.
This change has two benefits:
1. it avoids adding the type field to each and every instance of struct
fwnode_handle, thus saving memory and
2. makes the ops field the single factor that defines both the types of
the fwnode as well as defines the implementation of its operations,
decreasing the possibility of bugs when developing code dealing with
fwnode internals.
Suggested-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Add fwnode_device_is_available() to tell whether the device corresponding
to a certain fwnode_handle is available for use.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Move firmware specific implementations of the fwnode graph operations to
firmware specific locations.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The device and fwnode property API supports Devicetree, ACPI and pset
properties. The implementation of this functionality for each firmware
type was embedded in the fwnode property core. Move it out to firmware
type specific locations, making it easier to maintain.
Depends-on: ("of: Move OF property and graph API from base.c to property.c")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Functionally fwnode_property_read_string_array() should match
of_property_read_string_array() and work as a drop-in substitute for the
latter. of_property_read_string_array() returns the number of strings read
if the target string pointer array is non-NULL. Make
fwnode_property_read_string_array() do the same.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
DT has had concept of remote endpoints for some time already. It makes
possible to reference another firmware node through a property called
remote-endpoint. This is already used by some subsystems like v4l2 for
parsing hardware properties related to camera.
This patch adds ACPI support for remote endpoints utilizing _DSD
hierarchical data extensions.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The ACPI _DSD hierarchical data extension makes it possible to have
hierarchies deeper than one level in similar way than DT allows. These
"subsubnodes" have not been accessible because device property
implementation only provides device_get_next_child_node() that is limited
to direct descendants of a device.
We need this ability in order support things like remote endpoints
currently supported in DT with of_graph_* APIs.
Modify acpi_get_next_subnode() to accept fwnode handle instead and update
callers accordingly. Also add a new function fwnode_get_next_child_node()
that works directly with fwnodes and modify device_get_next_child_node() to
call it directly. While there add a macro fwnode_for_each_child_node()
analogous to the current device_for_each_child_node() but it works with
fwnodes instead of devices.
Link: http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.pdf
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Sometimes it is useful to be able to navigate firmware node hierarchy
upwards toward parent nodes. ACPI device nodes are pretty much already
supported because ACPICA provides acpi_get_parent(). ACPI data nodes,
however, are all below the same parent ACPI device. Their hierarchy is
created by "linking" each other using references in the value field.
Add parent pointer to the parent data node while we create them so it is
easy to navigate the hierarchy backwards. We use this parent pointer in a
new function acpi_node_get_parent() that is able to extract parent of both
ACPI firmware node types.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The definition document of the Hierarchical Properties Extension UUID
for _DSD has been changed recently to allow local references to be
used as sub-node link targets (previously, it only allowed strings to
be used for that purpose).
Update the code in drivers/acpi/property.c to reflect that change.
Link: http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.1.pdf
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
DT allows holes or empty phandles for references. This is used for example
in SPI subsystem where some chip selects are native and others are regular
GPIOs. In ACPI _DSD we currently do not support this but instead the
preceding reference consumes all following integer arguments.
For example we would like to support something like the below ASL fragment
for SPI:
Package () {
"cs-gpios",
Package () {
^GPIO, 19, 0, 0, // GPIO CS0
0, // Native CS
^GPIO, 20, 0, 0, // GPIO CS1
}
}
The zero in the middle means "no entry" or NULL reference. To support this
we change acpi_data_get_property_reference() to take firmware node and
num_args as argument and rename it to __acpi_node_get_property_reference().
The function returns -ENOENT if the given index resolves to "no entry"
reference and -ENODATA when there are no more entries in the property.
We then add static inline wrapper acpi_node_get_property_reference() that
passes MAX_ACPI_REFERENCE_ARGS as num_args to support the existing
behaviour which some drivers have been relying on.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When an ACPI node has both ACPI device nodes and ACPI data nodes,
acpi_get_next_subnode() will return the ACPI data nodes of its last
parsed child.
To avoid that, make acpi_get_next_subnode() go back to the original
ACPI device object when all of the device node children of it have
been found already.
Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Change return code to be in align with OF and built-in device properties error
codes. In particular -EINVAL means property is not found.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The correct scope for looking up the objects to generate data packages for
data-only subnodes pointed to by another data-only subnode is the scope
of the parent of that subnode and not the scope containing the _DSD object
at the top of the hierarchy (the latter works only if all of the objects
returning data-only subnode packages in a given hierarchy are in the same
scope).
Fix the code to work as expected.
Fixes: 445b0eb058 (ACPI / property: Add support for data-only subnodes)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Make device_get_next_child_node() work with ACPI data-only subnodes
introduced previously.
Namely, replace acpi_get_next_child() with acpi_get_next_subnode()
that can handle (and return) child device objects as well as child
data-only subnodes of the given device and modify the ACPI part
of the GPIO subsystem to handle data-only subnodes returned by it.
To that end, introduce acpi_node_get_gpiod() taking a struct
fwnode_handle pointer as the first argument. That argument may
point to an ACPI device object as well as to a data-only subnode
and the function should do the right thing (ie. look for the matching
GPIO descriptor correctly) in either case.
Next, modify fwnode_get_named_gpiod() to use acpi_node_get_gpiod()
instead of acpi_get_gpiod_by_index() which automatically causes
devm_get_gpiod_from_child() to work with ACPI data-only subnodes
that may be returned by device_get_next_child_node() which in turn
is required by the users of that function (the gpio_keys_polled
and gpio-leds drivers).
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Modify is_acpi_node() to return "true" for ACPI data-only subnodes as
well as for ACPI device objects and change the name of to_acpi_node()
to to_acpi_device_node() so it is clear that it covers ACPI device
objects only. Accordingly, introduce to_acpi_data_node() to cover
data-only subnodes in an analogous way.
With that, make the fwnode_property_* family of functions work with
ACPI data-only subnodes introduced previously.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Add infrastructure needed to expose data-only subnodes of ACPI
device objects introduced previously via sysfs.
Each data-only subnode is represented as a sysfs directory under
the directory corresponding to its parent object (a device or a
data-only subnode). Each of them has a "path" attribute (containing
the full ACPI namespace path to the object the subnode data come from)
at this time.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
In some cases, the information expressed via device properties is
hierarchical by nature. For example, the properties of a composite
device consisting of multiple semi-dependent components may need
to be represented in the form of a tree of property data sets
corresponding to specific components of the device.
Unfortunately, using ACPI device objects for this purpose turns out
to be problematic, mostly due to the assumption made by some operating
systems (that platform firmware generally needs to work with) that
each device object in the ACPI namespace represents a device requiring
a separate driver. That assumption leads to complications which
reportedly are impractically difficult to overcome and a different
approach is needed for the sake of interoperability.
The approach implemented here is based on extending _DSD via pointers
(links) to additional ACPI objects returning data packages formatted
in accordance with the _DSD formatting rules defined by Section 6.2.5
of ACPI 6. Those additional objects are referred to as data-only
subnodes of the device object containing the _DSD pointing to them.
The links to them need to be located in a separate section of the
_DSD data package following UUID dbb8e3e6-5886-4ba6-8795-1319f52a966b
referred to as the Hierarchical Data Extension UUID as defined in [1].
Each of them is represented by a package of two strings. The first
string in that package (the key) is regarded as the name of the
data-only subnode pointed to by the link. The second string in it
(the target) is expected to hold the ACPI namespace path (possibly
utilizing the usual ACPI namespace search rules) of an ACPI object
evaluating to a data package extending the _DSD.
The device properties initialization code follows those links,
creates a struct acpi_data_node object for each of them to store
the data returned by the ACPI object pointed to by it and processes
those data recursively (which may lead to the creation of more
struct acpi_data_node objects if the returned data package contains
the Hierarchical Data Extension UUID section with more links in it).
All of the struct acpi_data_node objects are present until the the
ACPI device object containing the _DSD with links to them is deleted
and they are deleted along with that object.
[1]: http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.pdf
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Move the extraction of _DSD properties from acpi_init_properties()
to a separate routine called acpi_extract_properties() to make the
subsequent changes more straightforward.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Obviously in the current place the 'else' keyword is redundant, though it seems
quite correct when we check if nval is in allowed range.
Reattach the condition branch there.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Use a #defined symbol ACPI_DT_NAMESPACE_HID instead of the PRP0001
string.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Refine the check for the presence of the "compatible" property
if the PRP0001 device ID is present in the device's list of
ACPI/PNP IDs to also print the message if _DSD is missing
entirely or the format of it is incorrect.
One special case to take into accout is that the "compatible"
property need not be provided for devices having the PRP0001
device ID in their lists of ACPI/PNP IDs if they are ancestors
of PRP0001 devices with the "compatible" property present.
This is to cover heriarchies of device objects where the kernel
is only supposed to use a struct device representation for the
topmost one and the others represent, for example, functional
blocks of a composite device.
While at it, reduce the log level of the message to "info"
and reduce the log level of the "broken _DSD" message to
"debug" (noise reduction).
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
The size_prop argument of the recently added function
acpi_dev_get_property_reference() is not used by the only current
caller of that function and is very unlikely to be used at any time
going forward.
Namely, for a property whose value is a list of items each containing
a references to a device object possibly accompanied by some integers,
the number of items in the list can always be computed as the number
of elements of type ACPI_TYPE_LOCAL_REFERENCE in the property package.
Thus it should never be necessary to provide an additional "cells"
property with a value equal to the number of items in that list. It
also should never be necessary to provide a "cells" property specifying
how many integers are supposed to be following each reference.
For this reason, drop the size_prop argument from
acpi_dev_get_property_reference() and update its caller accordingly.
Link: http://marc.info/?l=linux-kernel&m=141511255610556&w=2
Suggested-by: Grant Likely <grant.likely@linaro.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
We have lots of existing Device Tree enabled drivers and allocating
separate _HID for each is not feasible. Instead we allocate special _HID
"PRP0001" that means that the match should be done using Device Tree
compatible property using driver's .of_match_table instead if the driver
is missing .acpi_match_table.
If there is a need to distinguish from where the device is enumerated
(DT/ACPI) driver can check dev->of_node or ACPI_COMPATION(dev).
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Add a uniform interface by which device drivers can request device
properties from the platform firmware by providing a property name
and the corresponding data type. The purpose of it is to help to
write portable code that won't depend on any particular platform
firmware interface.
The following general helper functions are added:
device_property_present()
device_property_read_u8()
device_property_read_u16()
device_property_read_u32()
device_property_read_u64()
device_property_read_string()
device_property_read_u8_array()
device_property_read_u16_array()
device_property_read_u32_array()
device_property_read_u64_array()
device_property_read_string_array()
The first one allows the caller to check if the given property is
present. The next 5 of them allow single-valued properties of
various types to be retrieved in a uniform way. The remaining 5 are
for reading properties with multiple values (arrays of either numbers
or strings).
The interface covers both ACPI and Device Trees.
This change set includes material from Mika Westerberg and Aaron Lu.
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Device Tree is used in many embedded systems to describe the system
configuration to the OS. It supports attaching properties or name-value
pairs to the devices it describe. With these properties one can pass
additional information to the drivers that would not be available
otherwise.
ACPI is another configuration mechanism (among other things) typically
seen, but not limited to, x86 machines. ACPI allows passing arbitrary
data from methods but there has not been mechanism equivalent to Device
Tree until the introduction of _DSD in the recent publication of the
ACPI 5.1 specification.
In order to facilitate ACPI usage in systems where Device Tree is
typically used, it would be beneficial to standardize a way to retrieve
Device Tree style properties from ACPI devices, which is what we do in
this patch.
If a given device described in ACPI namespace wants to export properties it
must implement _DSD method (Device Specific Data, introduced with ACPI 5.1)
that returns the properties in a package of packages. For example:
Name (_DSD, Package () {
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
Package () {
Package () {"name1", <VALUE1>},
Package () {"name2", <VALUE2>},
...
}
})
The UUID reserved for properties is daffd814-6eba-4d8c-8a91-bc9bbf4aa301
and is documented in the ACPI 5.1 companion document called "_DSD
Implementation Guide" [1], [2].
We add several helper functions that can be used to extract these
properties and convert them to different Linux data types.
The ultimate goal is that we only have one device property API that
retrieves the requested properties from Device Tree or from ACPI
transparent to the caller.
[1] http://www.uefi.org/sites/default/files/resources/_DSD-implementation-guide-toplevel.htm
[2] http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Reviewed-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Linus Torvalds