[PATCH 0/4] platform/x86: wmi: Prepare for future changes

[PATCH 0/4] platform/x86: wmi: Prepare for future changes

[Armin Wolf]

After over a year of reverse engineering, i am finally ready to
introduce support for WMI-ACPI marshalling inside the WMI driver core.
Since the resulting patch series is quite large, i am planning to
submit the necessary patches as three separate patch series.

This is supposed to be the first of the three patch series. Its main
purpose is to prepare the WMI driver core for the upcoming changes.
The first patch fixes an issue inside the nls utf16 to utf8 conversion
code, while the next two patches fix some minor issues inside the WMI
driver core itself. The last patch finally moves the code of the WMI
driver core into a separate repository to allow for future additions
without cluttering the main directory.

Armin Wolf (4):
  fs/nls: Fix utf16 to utf8 conversion
  platform/x86: wmi: Use correct type when populating ACPI objects
  platform/x86: wmi: Remove extern keyword from prototypes
  platform/x86: wmi: Move WMI core code into a separate directory

 Documentation/driver-api/wmi.rst           |  2 +-
 MAINTAINERS                                |  2 +-
 drivers/platform/x86/Kconfig               | 30 +------------------
 drivers/platform/x86/Makefile              |  2 +-
 drivers/platform/x86/wmi/Kconfig           | 34 ++++++++++++++++++++++
 drivers/platform/x86/wmi/Makefile          |  8 +++++
 drivers/platform/x86/{wmi.c => wmi/core.c} | 34 +++++++++++++---------
 fs/nls/nls_base.c                          | 16 +++++++---
 include/linux/wmi.h                        | 15 ++++------
 9 files changed, 84 insertions(+), 59 deletions(-)
 create mode 100644 drivers/platform/x86/wmi/Kconfig
 create mode 100644 drivers/platform/x86/wmi/Makefile
 rename drivers/platform/x86/{wmi.c => wmi/core.c} (98%)

-- 
2.39.5

[PATCH 1/4] fs/nls: Fix utf16 to utf8 conversion

[Armin Wolf]

Currently the function responsible for converting between utf16 and
utf8 strings will ignore any characters that cannot be converted. This
however also includes multi-byte characters that do not fit into the
provided string buffer.

This can cause problems if such a multi-byte character is followed by
a single-byte character. In such a case the multi-byte character might
be ignored when the provided string buffer is too small, but the
single-byte character might fit and is thus still copied into the
resulting string.

Fix this by stop filling the provided string buffer once a character
does not fit. In order to be able to do this extend utf32_to_utf8()
to return useful errno codes instead of -1.

Fixes: 74675a58507e ("NLS: update handling of Unicode")
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
 fs/nls/nls_base.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/nls/nls_base.c b/fs/nls/nls_base.c
index 18d597e49a19..d434c4463a8f 100644
--- a/fs/nls/nls_base.c
+++ b/fs/nls/nls_base.c
@@ -94,7 +94,7 @@ int utf32_to_utf8(unicode_t u, u8 *s, int maxout)
 
 	l = u;
 	if (l > UNICODE_MAX || (l & SURROGATE_MASK) == SURROGATE_PAIR)
-		return -1;
+		return -EILSEQ;
 
 	nc = 0;
 	for (t = utf8_table; t->cmask && maxout; t++, maxout--) {
@@ -110,7 +110,7 @@ int utf32_to_utf8(unicode_t u, u8 *s, int maxout)
 			return nc;
 		}
 	}
-	return -1;
+	return -EOVERFLOW;
 }
 EXPORT_SYMBOL(utf32_to_utf8);
 
@@ -217,8 +217,16 @@ int utf16s_to_utf8s(const wchar_t *pwcs, int inlen, enum utf16_endian endian,
 				inlen--;
 			}
 			size = utf32_to_utf8(u, op, maxout);
-			if (size == -1) {
-				/* Ignore character and move on */
+			if (size < 0) {
+				if (size == -EILSEQ) {
+					/* Ignore character and move on */
+					continue;
+				}
+				/*
+				 * Stop filling the buffer with data once a character
+				 * does not fit anymore.
+				 */
+				break;
 			} else {
 				op += size;
 				maxout -= size;
-- 
2.39.5

[PATCH 2/4] platform/x86: wmi: Use correct type when populating ACPI objects

[Armin Wolf]

When evaluating a WMxx/WSxx ACPI control method, the data buffer
either needs to be passed as an ACPI buffer or as an ACPI string.
Use the correct type (buffer/string) when populating the associated
ACPI object.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
 drivers/platform/x86/wmi.c | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index 4e86a422f05f..6878c4fcb0b5 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -142,14 +142,6 @@ static inline void get_acpi_method_name(const struct wmi_block *wblock,
 	buffer[4] = '\0';
 }
 
-static inline acpi_object_type get_param_acpi_type(const struct wmi_block *wblock)
-{
-	if (wblock->gblock.flags & ACPI_WMI_STRING)
-		return ACPI_TYPE_STRING;
-	else
-		return ACPI_TYPE_BUFFER;
-}
-
 static int wmidev_match_guid(struct device *dev, const void *data)
 {
 	struct wmi_block *wblock = dev_to_wblock(dev);
@@ -351,9 +343,16 @@ acpi_status wmidev_evaluate_method(struct wmi_device *wdev, u8 instance, u32 met
 	params[0].integer.value = instance;
 	params[1].type = ACPI_TYPE_INTEGER;
 	params[1].integer.value = method_id;
-	params[2].type = get_param_acpi_type(wblock);
-	params[2].buffer.length = in->length;
-	params[2].buffer.pointer = in->pointer;
+
+	if (wblock->gblock.flags & ACPI_WMI_STRING) {
+		params[2].type = ACPI_TYPE_STRING;
+		params[2].string.length = in->length;
+		params[2].string.pointer = in->pointer;
+	} else {
+		params[2].type = ACPI_TYPE_BUFFER;
+		params[2].buffer.length = in->length;
+		params[2].buffer.pointer = in->pointer;
+	}
 
 	get_acpi_method_name(wblock, 'M', method);
 
@@ -519,9 +518,16 @@ acpi_status wmidev_block_set(struct wmi_device *wdev, u8 instance, const struct
 	input.pointer = params;
 	params[0].type = ACPI_TYPE_INTEGER;
 	params[0].integer.value = instance;
-	params[1].type = get_param_acpi_type(wblock);
-	params[1].buffer.length = in->length;
-	params[1].buffer.pointer = in->pointer;
+
+	if (wblock->gblock.flags & ACPI_WMI_STRING) {
+		params[1].type = ACPI_TYPE_STRING;
+		params[1].string.length = in->length;
+		params[1].string.pointer = in->pointer;
+	} else {
+		params[1].type = ACPI_TYPE_BUFFER;
+		params[1].buffer.length = in->length;
+		params[1].buffer.pointer = in->pointer;
+	}
 
 	get_acpi_method_name(wblock, 'S', method);
 
-- 
2.39.5

[PATCH 3/4] platform/x86: wmi: Remove extern keyword from prototypes

[Armin Wolf]

The external function definitions do not need the "extern" keyword.
Remove it to silence the associated checkpatch warnings.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
 include/linux/wmi.h | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/include/linux/wmi.h b/include/linux/wmi.h
index 10751c8e5e6a..665ea7dc8a92 100644
--- a/include/linux/wmi.h
+++ b/include/linux/wmi.h
@@ -36,13 +36,10 @@ struct wmi_device {
  */
 #define to_wmi_device(device)	container_of_const(device, struct wmi_device, dev)
 
-extern acpi_status wmidev_evaluate_method(struct wmi_device *wdev,
-					  u8 instance, u32 method_id,
-					  const struct acpi_buffer *in,
-					  struct acpi_buffer *out);
+acpi_status wmidev_evaluate_method(struct wmi_device *wdev, u8 instance, u32 method_id,
+				   const struct acpi_buffer *in, struct acpi_buffer *out);
 
-extern union acpi_object *wmidev_block_query(struct wmi_device *wdev,
-					     u8 instance);
+union acpi_object *wmidev_block_query(struct wmi_device *wdev, u8 instance);
 
 acpi_status wmidev_block_set(struct wmi_device *wdev, u8 instance, const struct acpi_buffer *in);
 
@@ -81,9 +78,9 @@ struct wmi_driver {
  */
 #define to_wmi_driver(drv)	container_of_const(drv, struct wmi_driver, driver)
 
-extern int __must_check __wmi_driver_register(struct wmi_driver *driver,
-					      struct module *owner);
-extern void wmi_driver_unregister(struct wmi_driver *driver);
+int __must_check __wmi_driver_register(struct wmi_driver *driver, struct module *owner);
+
+void wmi_driver_unregister(struct wmi_driver *driver);
 
 /**
  * wmi_driver_register() - Helper macro to register a WMI driver
-- 
2.39.5

[PATCH 4/4] platform/x86: wmi: Move WMI core code into a separate directory

[Armin Wolf]

Move the WMI core code into a separate directory to prepare for
future additions to the WMI driver.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
 Documentation/driver-api/wmi.rst           |  2 +-
 MAINTAINERS                                |  2 +-
 drivers/platform/x86/Kconfig               | 30 +------------------
 drivers/platform/x86/Makefile              |  2 +-
 drivers/platform/x86/wmi/Kconfig           | 34 ++++++++++++++++++++++
 drivers/platform/x86/wmi/Makefile          |  8 +++++
 drivers/platform/x86/{wmi.c => wmi/core.c} |  0
 7 files changed, 46 insertions(+), 32 deletions(-)
 create mode 100644 drivers/platform/x86/wmi/Kconfig
 create mode 100644 drivers/platform/x86/wmi/Makefile
 rename drivers/platform/x86/{wmi.c => wmi/core.c} (100%)

diff --git a/Documentation/driver-api/wmi.rst b/Documentation/driver-api/wmi.rst
index 4e8dbdb1fc67..66f0dda153b0 100644
--- a/Documentation/driver-api/wmi.rst
+++ b/Documentation/driver-api/wmi.rst
@@ -16,5 +16,5 @@ which will be bound to compatible WMI devices by the driver core.
 .. kernel-doc:: include/linux/wmi.h
    :internal:
 
-.. kernel-doc:: drivers/platform/x86/wmi.c
+.. kernel-doc:: drivers/platform/x86/wmi/core.c
    :export:
diff --git a/MAINTAINERS b/MAINTAINERS
index 46126ce2f968..abc0ff6769a8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -402,7 +402,7 @@ S:	Maintained
 F:	Documentation/ABI/testing/sysfs-bus-wmi
 F:	Documentation/driver-api/wmi.rst
 F:	Documentation/wmi/
-F:	drivers/platform/x86/wmi.c
+F:	drivers/platform/x86/wmi/
 F:	include/uapi/linux/wmi.h
 
 ACRN HYPERVISOR SERVICE MODULE
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 46e62feeda3c..ef59425580f3 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -16,35 +16,7 @@ menuconfig X86_PLATFORM_DEVICES
 
 if X86_PLATFORM_DEVICES
 
-config ACPI_WMI
-	tristate "WMI"
-	depends on ACPI
-	help
-	  This driver adds support for the ACPI-WMI (Windows Management
-	  Instrumentation) mapper device (PNP0C14) found on some systems.
-
-	  ACPI-WMI is a proprietary extension to ACPI to expose parts of the
-	  ACPI firmware to userspace - this is done through various vendor
-	  defined methods and data blocks in a PNP0C14 device, which are then
-	  made available for userspace to call.
-
-	  The implementation of this in Linux currently only exposes this to
-	  other kernel space drivers.
-
-	  This driver is a required dependency to build the firmware specific
-	  drivers needed on many machines, including Acer and HP laptops.
-
-	  It is safe to enable this driver even if your DSDT doesn't define
-	  any ACPI-WMI devices.
-
-config ACPI_WMI_LEGACY_DEVICE_NAMES
-	bool "Use legacy WMI device naming scheme"
-	depends on ACPI_WMI
-	help
-	  Say Y here to force the WMI driver core to use the old WMI device naming
-	  scheme when creating WMI devices. Doing so might be necessary for some
-	  userspace applications but will cause the registration of WMI devices with
-	  the same GUID to fail in some corner cases.
+source "drivers/platform/x86/wmi/Kconfig"
 
 config WMI_BMOF
 	tristate "WMI embedded Binary MOF driver"
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index c7db2a88c11a..c9f6e9275af8 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -5,7 +5,7 @@
 #
 
 # Windows Management Interface
-obj-$(CONFIG_ACPI_WMI)		+= wmi.o
+obj-y				+= wmi/
 obj-$(CONFIG_WMI_BMOF)		+= wmi-bmof.o
 
 # WMI drivers
diff --git a/drivers/platform/x86/wmi/Kconfig b/drivers/platform/x86/wmi/Kconfig
new file mode 100644
index 000000000000..9e7c84876ef5
--- /dev/null
+++ b/drivers/platform/x86/wmi/Kconfig
@@ -0,0 +1,34 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# ACPI WMI Core
+#
+
+config ACPI_WMI
+	tristate "WMI"
+	depends on ACPI
+	help
+	  This driver adds support for the ACPI-WMI (Windows Management
+	  Instrumentation) mapper device (PNP0C14) found on some systems.
+
+	  ACPI-WMI is a proprietary extension to ACPI to expose parts of the
+	  ACPI firmware to userspace - this is done through various vendor
+	  defined methods and data blocks in a PNP0C14 device, which are then
+	  made available for userspace to call.
+
+	  The implementation of this in Linux currently only exposes this to
+	  other kernel space drivers.
+
+	  This driver is a required dependency to build the firmware specific
+	  drivers needed on many machines, including Acer and HP laptops.
+
+	  It is safe to enable this driver even if your DSDT doesn't define
+	  any ACPI-WMI devices.
+
+config ACPI_WMI_LEGACY_DEVICE_NAMES
+	bool "Use legacy WMI device naming scheme"
+	depends on ACPI_WMI
+	help
+	  Say Y here to force the WMI driver core to use the old WMI device naming
+	  scheme when creating WMI devices. Doing so might be necessary for some
+	  userspace applications but will cause the registration of WMI devices with
+	  the same GUID to fail in some corner cases.
diff --git a/drivers/platform/x86/wmi/Makefile b/drivers/platform/x86/wmi/Makefile
new file mode 100644
index 000000000000..71b702936b59
--- /dev/null
+++ b/drivers/platform/x86/wmi/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for linux/drivers/platform/x86/wmi
+# ACPI WMI core
+#
+
+wmi-y			:= core.o
+obj-$(CONFIG_ACPI_WMI)	+= wmi.o
diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi/core.c
similarity index 100%
rename from drivers/platform/x86/wmi.c
rename to drivers/platform/x86/wmi/core.c
-- 
2.39.5

Re: [PATCH 0/4] platform/x86: wmi: Prepare for future changes

[Mario Limonciello]

On 11/4/25 2:45 PM, Armin Wolf wrote:
> After over a year of reverse engineering, i am finally ready to
> introduce support for WMI-ACPI marshalling inside the WMI driver core.
marshaling> Since the resulting patch series is quite large, i am 
planning to
> submit the necessary patches as three separate patch series.
> 
> This is supposed to be the first of the three patch series. Its main
> purpose is to prepare the WMI driver core for the upcoming changes.
> The first patch fixes an issue inside the nls utf16 to utf8 conversion
> code, while the next two patches fix some minor issues inside the WMI
> driver core itself. The last patch finally moves the code of the WMI
> driver core into a separate repository to allow for future additions
> without cluttering the main directory.

One question I have here on the patch to move things.

Since Windows on ARM (WoA) laptops are a thing - is this still actually 
x86 specific?  I am wondering if this should be moving to a different 
subsystem altogether like ACPI; especially now with this impending other 
large patch series you have on your way.
> 
> Armin Wolf (4):
>    fs/nls: Fix utf16 to utf8 conversion
>    platform/x86: wmi: Use correct type when populating ACPI objects
>    platform/x86: wmi: Remove extern keyword from prototypes
>    platform/x86: wmi: Move WMI core code into a separate directory
> 
>   Documentation/driver-api/wmi.rst           |  2 +-
>   MAINTAINERS                                |  2 +-
>   drivers/platform/x86/Kconfig               | 30 +------------------
>   drivers/platform/x86/Makefile              |  2 +-
>   drivers/platform/x86/wmi/Kconfig           | 34 ++++++++++++++++++++++
>   drivers/platform/x86/wmi/Makefile          |  8 +++++
>   drivers/platform/x86/{wmi.c => wmi/core.c} | 34 +++++++++++++---------
>   fs/nls/nls_base.c                          | 16 +++++++---
>   include/linux/wmi.h                        | 15 ++++------
>   9 files changed, 84 insertions(+), 59 deletions(-)
>   create mode 100644 drivers/platform/x86/wmi/Kconfig
>   create mode 100644 drivers/platform/x86/wmi/Makefile
>   rename drivers/platform/x86/{wmi.c => wmi/core.c} (98%)
> 

Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>

Re: [PATCH 4/4] platform/x86: wmi: Move WMI core code into a separate directory

[Ilpo Järvinen]

On Tue, 4 Nov 2025, Armin Wolf wrote:

> Move the WMI core code into a separate directory to prepare for
> future additions to the WMI driver.
> 
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> ---
>  Documentation/driver-api/wmi.rst           |  2 +-
>  MAINTAINERS                                |  2 +-
>  drivers/platform/x86/Kconfig               | 30 +------------------
>  drivers/platform/x86/Makefile              |  2 +-
>  drivers/platform/x86/wmi/Kconfig           | 34 ++++++++++++++++++++++
>  drivers/platform/x86/wmi/Makefile          |  8 +++++
>  drivers/platform/x86/{wmi.c => wmi/core.c} |  0
>  7 files changed, 46 insertions(+), 32 deletions(-)
>  create mode 100644 drivers/platform/x86/wmi/Kconfig
>  create mode 100644 drivers/platform/x86/wmi/Makefile
>  rename drivers/platform/x86/{wmi.c => wmi/core.c} (100%)
> 
> diff --git a/Documentation/driver-api/wmi.rst b/Documentation/driver-api/wmi.rst
> index 4e8dbdb1fc67..66f0dda153b0 100644
> --- a/Documentation/driver-api/wmi.rst
> +++ b/Documentation/driver-api/wmi.rst
> @@ -16,5 +16,5 @@ which will be bound to compatible WMI devices by the driver core.
>  .. kernel-doc:: include/linux/wmi.h
>     :internal:
>  
> -.. kernel-doc:: drivers/platform/x86/wmi.c
> +.. kernel-doc:: drivers/platform/x86/wmi/core.c
>     :export:
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 46126ce2f968..abc0ff6769a8 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -402,7 +402,7 @@ S:	Maintained
>  F:	Documentation/ABI/testing/sysfs-bus-wmi
>  F:	Documentation/driver-api/wmi.rst
>  F:	Documentation/wmi/
> -F:	drivers/platform/x86/wmi.c
> +F:	drivers/platform/x86/wmi/
>  F:	include/uapi/linux/wmi.h
>  
>  ACRN HYPERVISOR SERVICE MODULE
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 46e62feeda3c..ef59425580f3 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -16,35 +16,7 @@ menuconfig X86_PLATFORM_DEVICES
>  
>  if X86_PLATFORM_DEVICES
>  
> -config ACPI_WMI
> -	tristate "WMI"
> -	depends on ACPI
> -	help
> -	  This driver adds support for the ACPI-WMI (Windows Management
> -	  Instrumentation) mapper device (PNP0C14) found on some systems.
> -
> -	  ACPI-WMI is a proprietary extension to ACPI to expose parts of the
> -	  ACPI firmware to userspace - this is done through various vendor
> -	  defined methods and data blocks in a PNP0C14 device, which are then
> -	  made available for userspace to call.
> -
> -	  The implementation of this in Linux currently only exposes this to
> -	  other kernel space drivers.
> -
> -	  This driver is a required dependency to build the firmware specific
> -	  drivers needed on many machines, including Acer and HP laptops.
> -
> -	  It is safe to enable this driver even if your DSDT doesn't define
> -	  any ACPI-WMI devices.
> -
> -config ACPI_WMI_LEGACY_DEVICE_NAMES
> -	bool "Use legacy WMI device naming scheme"
> -	depends on ACPI_WMI
> -	help
> -	  Say Y here to force the WMI driver core to use the old WMI device naming
> -	  scheme when creating WMI devices. Doing so might be necessary for some
> -	  userspace applications but will cause the registration of WMI devices with
> -	  the same GUID to fail in some corner cases.
> +source "drivers/platform/x86/wmi/Kconfig"
>  
>  config WMI_BMOF
>  	tristate "WMI embedded Binary MOF driver"
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index c7db2a88c11a..c9f6e9275af8 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -5,7 +5,7 @@
>  #
>  
>  # Windows Management Interface
> -obj-$(CONFIG_ACPI_WMI)		+= wmi.o
> +obj-y				+= wmi/

Is there a good reason for the first part of the change?
That is, do you anticipate need for something outside of what this would 
cover:

obj-$(CONFIG_ACPI_WMI)               += wmi/

Other than that, this series looks fine.

-- 
 i.


>  obj-$(CONFIG_WMI_BMOF)		+= wmi-bmof.o
>  
>  # WMI drivers
> diff --git a/drivers/platform/x86/wmi/Kconfig b/drivers/platform/x86/wmi/Kconfig
> new file mode 100644
> index 000000000000..9e7c84876ef5
> --- /dev/null
> +++ b/drivers/platform/x86/wmi/Kconfig
> @@ -0,0 +1,34 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +#
> +# ACPI WMI Core
> +#
> +
> +config ACPI_WMI
> +	tristate "WMI"
> +	depends on ACPI
> +	help
> +	  This driver adds support for the ACPI-WMI (Windows Management
> +	  Instrumentation) mapper device (PNP0C14) found on some systems.
> +
> +	  ACPI-WMI is a proprietary extension to ACPI to expose parts of the
> +	  ACPI firmware to userspace - this is done through various vendor
> +	  defined methods and data blocks in a PNP0C14 device, which are then
> +	  made available for userspace to call.
> +
> +	  The implementation of this in Linux currently only exposes this to
> +	  other kernel space drivers.
> +
> +	  This driver is a required dependency to build the firmware specific
> +	  drivers needed on many machines, including Acer and HP laptops.
> +
> +	  It is safe to enable this driver even if your DSDT doesn't define
> +	  any ACPI-WMI devices.
> +
> +config ACPI_WMI_LEGACY_DEVICE_NAMES
> +	bool "Use legacy WMI device naming scheme"
> +	depends on ACPI_WMI
> +	help
> +	  Say Y here to force the WMI driver core to use the old WMI device naming
> +	  scheme when creating WMI devices. Doing so might be necessary for some
> +	  userspace applications but will cause the registration of WMI devices with
> +	  the same GUID to fail in some corner cases.
> diff --git a/drivers/platform/x86/wmi/Makefile b/drivers/platform/x86/wmi/Makefile
> new file mode 100644
> index 000000000000..71b702936b59
> --- /dev/null
> +++ b/drivers/platform/x86/wmi/Makefile
> @@ -0,0 +1,8 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Makefile for linux/drivers/platform/x86/wmi
> +# ACPI WMI core
> +#
> +
> +wmi-y			:= core.o
> +obj-$(CONFIG_ACPI_WMI)	+= wmi.o
> diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi/core.c
> similarity index 100%
> rename from drivers/platform/x86/wmi.c
> rename to drivers/platform/x86/wmi/core.c
> 

Re: [PATCH 4/4] platform/x86: wmi: Move WMI core code into a separate directory

[Armin Wolf]

Am 05.11.25 um 10:41 schrieb Ilpo Järvinen:

> On Tue, 4 Nov 2025, Armin Wolf wrote:
>
>> Move the WMI core code into a separate directory to prepare for
>> future additions to the WMI driver.
>>
>> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
>> ---
>>   Documentation/driver-api/wmi.rst           |  2 +-
>>   MAINTAINERS                                |  2 +-
>>   drivers/platform/x86/Kconfig               | 30 +------------------
>>   drivers/platform/x86/Makefile              |  2 +-
>>   drivers/platform/x86/wmi/Kconfig           | 34 ++++++++++++++++++++++
>>   drivers/platform/x86/wmi/Makefile          |  8 +++++
>>   drivers/platform/x86/{wmi.c => wmi/core.c} |  0
>>   7 files changed, 46 insertions(+), 32 deletions(-)
>>   create mode 100644 drivers/platform/x86/wmi/Kconfig
>>   create mode 100644 drivers/platform/x86/wmi/Makefile
>>   rename drivers/platform/x86/{wmi.c => wmi/core.c} (100%)
>>
>> diff --git a/Documentation/driver-api/wmi.rst b/Documentation/driver-api/wmi.rst
>> index 4e8dbdb1fc67..66f0dda153b0 100644
>> --- a/Documentation/driver-api/wmi.rst
>> +++ b/Documentation/driver-api/wmi.rst
>> @@ -16,5 +16,5 @@ which will be bound to compatible WMI devices by the driver core.
>>   .. kernel-doc:: include/linux/wmi.h
>>      :internal:
>>   
>> -.. kernel-doc:: drivers/platform/x86/wmi.c
>> +.. kernel-doc:: drivers/platform/x86/wmi/core.c
>>      :export:
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 46126ce2f968..abc0ff6769a8 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -402,7 +402,7 @@ S:	Maintained
>>   F:	Documentation/ABI/testing/sysfs-bus-wmi
>>   F:	Documentation/driver-api/wmi.rst
>>   F:	Documentation/wmi/
>> -F:	drivers/platform/x86/wmi.c
>> +F:	drivers/platform/x86/wmi/
>>   F:	include/uapi/linux/wmi.h
>>   
>>   ACRN HYPERVISOR SERVICE MODULE
>> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
>> index 46e62feeda3c..ef59425580f3 100644
>> --- a/drivers/platform/x86/Kconfig
>> +++ b/drivers/platform/x86/Kconfig
>> @@ -16,35 +16,7 @@ menuconfig X86_PLATFORM_DEVICES
>>   
>>   if X86_PLATFORM_DEVICES
>>   
>> -config ACPI_WMI
>> -	tristate "WMI"
>> -	depends on ACPI
>> -	help
>> -	  This driver adds support for the ACPI-WMI (Windows Management
>> -	  Instrumentation) mapper device (PNP0C14) found on some systems.
>> -
>> -	  ACPI-WMI is a proprietary extension to ACPI to expose parts of the
>> -	  ACPI firmware to userspace - this is done through various vendor
>> -	  defined methods and data blocks in a PNP0C14 device, which are then
>> -	  made available for userspace to call.
>> -
>> -	  The implementation of this in Linux currently only exposes this to
>> -	  other kernel space drivers.
>> -
>> -	  This driver is a required dependency to build the firmware specific
>> -	  drivers needed on many machines, including Acer and HP laptops.
>> -
>> -	  It is safe to enable this driver even if your DSDT doesn't define
>> -	  any ACPI-WMI devices.
>> -
>> -config ACPI_WMI_LEGACY_DEVICE_NAMES
>> -	bool "Use legacy WMI device naming scheme"
>> -	depends on ACPI_WMI
>> -	help
>> -	  Say Y here to force the WMI driver core to use the old WMI device naming
>> -	  scheme when creating WMI devices. Doing so might be necessary for some
>> -	  userspace applications but will cause the registration of WMI devices with
>> -	  the same GUID to fail in some corner cases.
>> +source "drivers/platform/x86/wmi/Kconfig"
>>   
>>   config WMI_BMOF
>>   	tristate "WMI embedded Binary MOF driver"
>> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
>> index c7db2a88c11a..c9f6e9275af8 100644
>> --- a/drivers/platform/x86/Makefile
>> +++ b/drivers/platform/x86/Makefile
>> @@ -5,7 +5,7 @@
>>   #
>>   
>>   # Windows Management Interface
>> -obj-$(CONFIG_ACPI_WMI)		+= wmi.o
>> +obj-y				+= wmi/
> Is there a good reason for the first part of the change?
> That is, do you anticipate need for something outside of what this would
> cover:
>
> obj-$(CONFIG_ACPI_WMI)               += wmi/
>
> Other than that, this series looks fine.

The final version will look like this:

wmi-y                   := core.o marshalling.o string.o
obj-$(CONFIG_ACPI_WMI)  += wmi.o

# Unit tests
obj-y                   += tests/

So i think this change is necessary.

Thanks,
Armin Wolf

Re: [PATCH 0/4] platform/x86: wmi: Prepare for future changes

[Armin Wolf]

Am 04.11.25 um 21:52 schrieb Mario Limonciello:

> On 11/4/25 2:45 PM, Armin Wolf wrote:
>> After over a year of reverse engineering, i am finally ready to
>> introduce support for WMI-ACPI marshalling inside the WMI driver core.
> marshaling> Since the resulting patch series is quite large, i am 
> planning to
>> submit the necessary patches as three separate patch series.
>>
>> This is supposed to be the first of the three patch series. Its main
>> purpose is to prepare the WMI driver core for the upcoming changes.
>> The first patch fixes an issue inside the nls utf16 to utf8 conversion
>> code, while the next two patches fix some minor issues inside the WMI
>> driver core itself. The last patch finally moves the code of the WMI
>> driver core into a separate repository to allow for future additions
>> without cluttering the main directory.
>
> One question I have here on the patch to move things.
>
> Since Windows on ARM (WoA) laptops are a thing - is this still 
> actually x86 specific?  I am wondering if this should be moving to a 
> different subsystem altogether like ACPI; especially now with this 
> impending other large patch series you have on your way.

I know of a few WoA laptops that contain ACPI-WMI devices, meaning this driver is indeed not x86-specific.
However i need to make some changes to the WMI driver core (and actually tests it on a AArch64 VM) first
before moving it out of drivers/platform/x86.

Once i am actually ready for this i would prefer to move the whole stuff to drivers/platform, as drivers/acpi
IMHO is better suited for core ACPI drivers.

Thanks,
Armin Wolf

>>
>> Armin Wolf (4):
>>    fs/nls: Fix utf16 to utf8 conversion
>>    platform/x86: wmi: Use correct type when populating ACPI objects
>>    platform/x86: wmi: Remove extern keyword from prototypes
>>    platform/x86: wmi: Move WMI core code into a separate directory
>>
>>   Documentation/driver-api/wmi.rst           |  2 +-
>>   MAINTAINERS                                |  2 +-
>>   drivers/platform/x86/Kconfig               | 30 +------------------
>>   drivers/platform/x86/Makefile              |  2 +-
>>   drivers/platform/x86/wmi/Kconfig           | 34 ++++++++++++++++++++++
>>   drivers/platform/x86/wmi/Makefile          |  8 +++++
>>   drivers/platform/x86/{wmi.c => wmi/core.c} | 34 +++++++++++++---------
>>   fs/nls/nls_base.c                          | 16 +++++++---
>>   include/linux/wmi.h                        | 15 ++++------
>>   9 files changed, 84 insertions(+), 59 deletions(-)
>>   create mode 100644 drivers/platform/x86/wmi/Kconfig
>>   create mode 100644 drivers/platform/x86/wmi/Makefile
>>   rename drivers/platform/x86/{wmi.c => wmi/core.c} (98%)
>>
>
> Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>

Re: [PATCH 4/4] platform/x86: wmi: Move WMI core code into a separate directory

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 4772 bytes --]

On Wed, 5 Nov 2025, Armin Wolf wrote:

> Am 05.11.25 um 10:41 schrieb Ilpo Järvinen:
> 
> > On Tue, 4 Nov 2025, Armin Wolf wrote:
> > 
> > > Move the WMI core code into a separate directory to prepare for
> > > future additions to the WMI driver.
> > > 
> > > Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> > > ---
> > >   Documentation/driver-api/wmi.rst           |  2 +-
> > >   MAINTAINERS                                |  2 +-
> > >   drivers/platform/x86/Kconfig               | 30 +------------------
> > >   drivers/platform/x86/Makefile              |  2 +-
> > >   drivers/platform/x86/wmi/Kconfig           | 34 ++++++++++++++++++++++
> > >   drivers/platform/x86/wmi/Makefile          |  8 +++++
> > >   drivers/platform/x86/{wmi.c => wmi/core.c} |  0
> > >   7 files changed, 46 insertions(+), 32 deletions(-)
> > >   create mode 100644 drivers/platform/x86/wmi/Kconfig
> > >   create mode 100644 drivers/platform/x86/wmi/Makefile
> > >   rename drivers/platform/x86/{wmi.c => wmi/core.c} (100%)
> > > 
> > > diff --git a/Documentation/driver-api/wmi.rst
> > > b/Documentation/driver-api/wmi.rst
> > > index 4e8dbdb1fc67..66f0dda153b0 100644
> > > --- a/Documentation/driver-api/wmi.rst
> > > +++ b/Documentation/driver-api/wmi.rst
> > > @@ -16,5 +16,5 @@ which will be bound to compatible WMI devices by the
> > > driver core.
> > >   .. kernel-doc:: include/linux/wmi.h
> > >      :internal:
> > >   -.. kernel-doc:: drivers/platform/x86/wmi.c
> > > +.. kernel-doc:: drivers/platform/x86/wmi/core.c
> > >      :export:
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index 46126ce2f968..abc0ff6769a8 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -402,7 +402,7 @@ S:	Maintained
> > >   F:	Documentation/ABI/testing/sysfs-bus-wmi
> > >   F:	Documentation/driver-api/wmi.rst
> > >   F:	Documentation/wmi/
> > > -F:	drivers/platform/x86/wmi.c
> > > +F:	drivers/platform/x86/wmi/
> > >   F:	include/uapi/linux/wmi.h
> > >     ACRN HYPERVISOR SERVICE MODULE
> > > diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> > > index 46e62feeda3c..ef59425580f3 100644
> > > --- a/drivers/platform/x86/Kconfig
> > > +++ b/drivers/platform/x86/Kconfig
> > > @@ -16,35 +16,7 @@ menuconfig X86_PLATFORM_DEVICES
> > >     if X86_PLATFORM_DEVICES
> > >   -config ACPI_WMI
> > > -	tristate "WMI"
> > > -	depends on ACPI
> > > -	help
> > > -	  This driver adds support for the ACPI-WMI (Windows Management
> > > -	  Instrumentation) mapper device (PNP0C14) found on some systems.
> > > -
> > > -	  ACPI-WMI is a proprietary extension to ACPI to expose parts of the
> > > -	  ACPI firmware to userspace - this is done through various vendor
> > > -	  defined methods and data blocks in a PNP0C14 device, which are then
> > > -	  made available for userspace to call.
> > > -
> > > -	  The implementation of this in Linux currently only exposes this to
> > > -	  other kernel space drivers.
> > > -
> > > -	  This driver is a required dependency to build the firmware specific
> > > -	  drivers needed on many machines, including Acer and HP laptops.
> > > -
> > > -	  It is safe to enable this driver even if your DSDT doesn't define
> > > -	  any ACPI-WMI devices.
> > > -
> > > -config ACPI_WMI_LEGACY_DEVICE_NAMES
> > > -	bool "Use legacy WMI device naming scheme"
> > > -	depends on ACPI_WMI
> > > -	help
> > > -	  Say Y here to force the WMI driver core to use the old WMI device
> > > naming
> > > -	  scheme when creating WMI devices. Doing so might be necessary for
> > > some
> > > -	  userspace applications but will cause the registration of WMI
> > > devices with
> > > -	  the same GUID to fail in some corner cases.
> > > +source "drivers/platform/x86/wmi/Kconfig"
> > >     config WMI_BMOF
> > >   	tristate "WMI embedded Binary MOF driver"
> > > diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> > > index c7db2a88c11a..c9f6e9275af8 100644
> > > --- a/drivers/platform/x86/Makefile
> > > +++ b/drivers/platform/x86/Makefile
> > > @@ -5,7 +5,7 @@
> > >   #
> > >     # Windows Management Interface
> > > -obj-$(CONFIG_ACPI_WMI)		+= wmi.o
> > > +obj-y				+= wmi/
> > Is there a good reason for the first part of the change?
> > That is, do you anticipate need for something outside of what this would
> > cover:
> > 
> > obj-$(CONFIG_ACPI_WMI)               += wmi/
> > 
> > Other than that, this series looks fine.
> 
> The final version will look like this:
> 
> wmi-y                   := core.o marshalling.o string.o
> obj-$(CONFIG_ACPI_WMI)  += wmi.o
> 
> # Unit tests
> obj-y                   += tests/
> 
> So i think this change is necessary.

Fair enough.

-- 
 i.

Re: [PATCH 0/4] platform/x86: wmi: Prepare for future changes

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 3375 bytes --]

On Wed, 5 Nov 2025, Armin Wolf wrote:

> Am 04.11.25 um 21:52 schrieb Mario Limonciello:
> 
> > On 11/4/25 2:45 PM, Armin Wolf wrote:
> > > After over a year of reverse engineering, i am finally ready to
> > > introduce support for WMI-ACPI marshalling inside the WMI driver core.
> > marshaling> Since the resulting patch series is quite large, i am planning
> > to
> > > submit the necessary patches as three separate patch series.
> > > 
> > > This is supposed to be the first of the three patch series. Its main
> > > purpose is to prepare the WMI driver core for the upcoming changes.
> > > The first patch fixes an issue inside the nls utf16 to utf8 conversion
> > > code, while the next two patches fix some minor issues inside the WMI
> > > driver core itself. The last patch finally moves the code of the WMI
> > > driver core into a separate repository to allow for future additions
> > > without cluttering the main directory.
> > 
> > One question I have here on the patch to move things.
> > 
> > Since Windows on ARM (WoA) laptops are a thing - is this still actually x86
> > specific?  I am wondering if this should be moving to a different subsystem
> > altogether like ACPI; especially now with this impending other large patch
> > series you have on your way.
> 
> I know of a few WoA laptops that contain ACPI-WMI devices, meaning this driver
> is indeed not x86-specific.
> However i need to make some changes to the WMI driver core (and actually tests
> it on a AArch64 VM) first
> before moving it out of drivers/platform/x86.
> 
> Once i am actually ready for this i would prefer to move the whole stuff to
> drivers/platform, as drivers/acpi
> IMHO is better suited for core ACPI drivers.

So no need to put it under drivers/platform/x86/wmi/ then at all. It 
can move directly to drivers/platform/wmi/ and you work there towards 
making it non-x86-specific.

-- 
 i.

> 
> Thanks,
> Armin Wolf
> 
> > > 
> > > Armin Wolf (4):
> > >    fs/nls: Fix utf16 to utf8 conversion
> > >    platform/x86: wmi: Use correct type when populating ACPI objects
> > >    platform/x86: wmi: Remove extern keyword from prototypes
> > >    platform/x86: wmi: Move WMI core code into a separate directory
> > > 
> > >   Documentation/driver-api/wmi.rst           |  2 +-
> > >   MAINTAINERS                                |  2 +-
> > >   drivers/platform/x86/Kconfig               | 30 +------------------
> > >   drivers/platform/x86/Makefile              |  2 +-
> > >   drivers/platform/x86/wmi/Kconfig           | 34 ++++++++++++++++++++++
> > >   drivers/platform/x86/wmi/Makefile          |  8 +++++
> > >   drivers/platform/x86/{wmi.c => wmi/core.c} | 34 +++++++++++++---------
> > >   fs/nls/nls_base.c                          | 16 +++++++---
> > >   include/linux/wmi.h                        | 15 ++++------
> > >   9 files changed, 84 insertions(+), 59 deletions(-)
> > >   create mode 100644 drivers/platform/x86/wmi/Kconfig
> > >   create mode 100644 drivers/platform/x86/wmi/Makefile
> > >   rename drivers/platform/x86/{wmi.c => wmi/core.c} (98%)
> > > 
> > 
> > Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
> 

Re: [PATCH 0/4] platform/x86: wmi: Prepare for future changes

[Armin Wolf]

Am 10.11.25 um 12:00 schrieb Ilpo Järvinen:

> On Wed, 5 Nov 2025, Armin Wolf wrote:
>
>> Am 04.11.25 um 21:52 schrieb Mario Limonciello:
>>
>>> On 11/4/25 2:45 PM, Armin Wolf wrote:
>>>> After over a year of reverse engineering, i am finally ready to
>>>> introduce support for WMI-ACPI marshalling inside the WMI driver core.
>>> marshaling> Since the resulting patch series is quite large, i am planning
>>> to
>>>> submit the necessary patches as three separate patch series.
>>>>
>>>> This is supposed to be the first of the three patch series. Its main
>>>> purpose is to prepare the WMI driver core for the upcoming changes.
>>>> The first patch fixes an issue inside the nls utf16 to utf8 conversion
>>>> code, while the next two patches fix some minor issues inside the WMI
>>>> driver core itself. The last patch finally moves the code of the WMI
>>>> driver core into a separate repository to allow for future additions
>>>> without cluttering the main directory.
>>> One question I have here on the patch to move things.
>>>
>>> Since Windows on ARM (WoA) laptops are a thing - is this still actually x86
>>> specific?  I am wondering if this should be moving to a different subsystem
>>> altogether like ACPI; especially now with this impending other large patch
>>> series you have on your way.
>> I know of a few WoA laptops that contain ACPI-WMI devices, meaning this driver
>> is indeed not x86-specific.
>> However i need to make some changes to the WMI driver core (and actually tests
>> it on a AArch64 VM) first
>> before moving it out of drivers/platform/x86.
>>
>> Once i am actually ready for this i would prefer to move the whole stuff to
>> drivers/platform, as drivers/acpi
>> IMHO is better suited for core ACPI drivers.
> So no need to put it under drivers/platform/x86/wmi/ then at all. It
> can move directly to drivers/platform/wmi/ and you work there towards
> making it non-x86-specific.

OK, i will send the v2 revision of this series soon.

Thanks,
Armin Wolf