On Wed, Mar 26, 2025 at 6:29 PM Armin Wolf <W_Armin@xxxxxx> wrote:
>
> Am 17.03.25 um 15:43 schrieb Derek J. Clark:
>
> > Adds lenovo-wmi-capdata01 driver which provides the
> > LENOVO_CAPABILITY_DATA_01 WMI data block that comes on "Other Mode"
> > enabled hardware. Provides an interface for querying if a given
> > attribute is supported by the hardware, as well as its default_value,
> > max_value, min_value, and step increment.
> >
> > Signed-off-by: Derek J. Clark <derekjohn.clark@xxxxxxxxx>
> > ---
> > v4:
> > - Make driver data a private struct, remove references from Other Mode
> > driver.
> > - Don't cache data at device initialization. Instead, on component bind,
> > cache the data on a member variable of the Other Mode driver data
> > passed as a void pointer.
> > - Add header file for capdata01 structs.
> > - Add new struct to pass capdata01 array data and array length to Other
> > Mode.
> > v3:
> > - Add as component to lenovo-wmi-other driver.
> > v2:
> > - Use devm_kmalloc to ensure driver can be instanced, remove global
> > reference.
> > - Ensure reverse Christmas tree for all variable declarations.
> > - Remove extra whitespace.
> > - Use guard(mutex) in all mutex instances, global mutex.
> > - Use pr_fmt instead of adding the driver name to each pr_err.
> > - Remove noisy pr_info usage.
> > - Rename capdata_wmi to lenovo_wmi_cd01_priv and cd01_wmi to priv.
> > - Use list to get the lenovo_wmi_cd01_priv instance in
> > lenovo_wmi_capdata01_get as none of the data provided by the macros
> > that will use it can pass a member of the struct for use in
> > container_of.
> > ---
> > MAINTAINERS | 2 +
> > drivers/platform/x86/Kconfig | 4 +
> > drivers/platform/x86/Makefile | 1 +
> > drivers/platform/x86/lenovo-wmi-capdata01.c | 136 ++++++++++++++++++++
> > drivers/platform/x86/lenovo-wmi-capdata01.h | 29 +++++
> > 5 files changed, 172 insertions(+)
> > create mode 100644 drivers/platform/x86/lenovo-wmi-capdata01.c
> > create mode 100644 drivers/platform/x86/lenovo-wmi-capdata01.h
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 6dde75922aaf..56ead241a053 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -13164,6 +13164,8 @@ L: platform-driver-x86@xxxxxxxxxxxxxxx
> > S: Maintained
> > F: Documentation/wmi/devices/lenovo-wmi-gamezone.rst
> > F: Documentation/wmi/devices/lenovo-wmi-other.rst
> > +F: drivers/platform/x86/lenovo-wmi-capdata01.c
> > +F: drivers/platform/x86/lenovo-wmi-capdata01.h
> > F: drivers/platform/x86/lenovo-wmi-events.c
> > F: drivers/platform/x86/lenovo-wmi-events.h
> > F: drivers/platform/x86/lenovo-wmi-helpers.c
> > diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> > index 13b8f4ac5dc5..64663667f0cb 100644
> > --- a/drivers/platform/x86/Kconfig
> > +++ b/drivers/platform/x86/Kconfig
> > @@ -467,6 +467,10 @@ config LENOVO_WMI_HELPERS
> > tristate
> > depends on ACPI_WMI
> >
> > +config LENOVO_WMI_DATA01
> > + tristate
> > + depends on ACPI_WMI
> > +
> > config IDEAPAD_LAPTOP
> > tristate "Lenovo IdeaPad Laptop Extras"
> > depends on ACPI
> > diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> > index fc039839286a..7a35c77221b7 100644
> > --- a/drivers/platform/x86/Makefile
> > +++ b/drivers/platform/x86/Makefile
> > @@ -69,6 +69,7 @@ obj-$(CONFIG_THINKPAD_LMI) += think-lmi.o
> > obj-$(CONFIG_YOGABOOK) += lenovo-yogabook.o
> > obj-$(CONFIG_YT2_1380) += lenovo-yoga-tab2-pro-1380-fastcharger.o
> > obj-$(CONFIG_LENOVO_WMI_CAMERA) += lenovo-wmi-camera.o
> > +obj-$(CONFIG_LENOVO_WMI_DATA01) += lenovo-wmi-capdata01.o
> > obj-$(CONFIG_LENOVO_WMI_EVENTS) += lenovo-wmi-events.o
> > obj-$(CONFIG_LENOVO_WMI_HELPERS) += lenovo-wmi-helpers.o
> >
> > diff --git a/drivers/platform/x86/lenovo-wmi-capdata01.c b/drivers/platform/x86/lenovo-wmi-capdata01.c
> > new file mode 100644
> > index 000000000000..b6876611ffd9
> > --- /dev/null
> > +++ b/drivers/platform/x86/lenovo-wmi-capdata01.c
> > @@ -0,0 +1,136 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * LENOVO_CAPABILITY_DATA_01 WMI data block driver. This interface provides
> > + * information on tunable attributes used by the "Other Mode" WMI interface,
> > + * including if it is supported by the hardware, the default_value, max_value,
> > + * min_value, and step increment.
> > + *
> > + * Copyright(C) 2025 Derek J. Clark <derekjohn.clark@xxxxxxxxx>
> > + */
> > +
> > +#include <linux/cleanup.h>
> > +#include <linux/component.h>
> > +#include <linux/container_of.h>
> > +#include <linux/device.h>
> > +#include <linux/gfp_types.h>
> > +#include <linux/types.h>
> > +#include <linux/wmi.h>
> > +#include "lenovo-wmi-capdata01.h"
>
> Hi,
>
> please also include linux/acpi.h, linux/export.h and linux/module.h.
>
> > +
> > +/* Interface GUIDs */
> > +#define LENOVO_CAPABILITY_DATA_01_GUID "7A8F5407-CB67-4D6E-B547-39B3BE018154"
> > +
> > +struct lwmi_cd01_priv {
> > + struct wmi_device *wdev;
> > +};
> > +
> > +/*
>
> /* -> /**
>
> > + * lenovo_cd01_component_bind() - On master bind, caches all capability data on
> > + * the master device.
> > + * @cd01_dev: Pointer to the capability data 01 parent device.
> > + * @om_dev: Pointer to the other mode parent device.
> > + * @data: capdata01_list object pointer to return the capability data with.
> > + *
> > + * Returns: 0, or an error.
> > + */
> > +static int lenovo_cd01_component_bind(struct device *cd01_dev,
> > + struct device *om_dev, void *data)
> > +{
> > + struct lwmi_cd01_priv *priv = dev_get_drvdata(cd01_dev);
> > + int count, idx;
> > +
> > + if (!priv)
> > + return -ENODEV;
>
> This check is unnecessary, please drop.
>
Acked
> > +
> > + count = wmidev_instance_count(priv->wdev);
> > +
> > + if (count == 0)
> > + return -EINVAL;
>
> The WMI driver core already ensures that WMI devices with 0 instances are
> rejected. Please drop this check.
>
Good to know, thanks.
> > +
> > + ((struct cd01_list *)data)->count = count;
> > + ((struct cd01_list *)data)->data = devm_kmalloc_array(om_dev, count,
> > + sizeof(struct capdata01 *),
> > + GFP_KERNEL);
>
> Two things:
>
> - using a local variable with a type of struct cd01_list * results in cleaner source code here
>
> - using devres is not possible inside the component callbacks, since the lifetime of the component
> device is not necessarily tied to the lifetime of the underlying device.
>
> I suggest you move the whole WMI data querying into lwmi_cd01_probe(), because then you can keep using
> devres.
>
Doing this in probe() puts the list on lwmi_cd01_priv. Should I copy
that data on bind, or pass back a pointer to the cd01 device struct
and use an exported function on cd01 and dev_get_drvdata to access
priv->list->data[idx] when needed? I prefer the latter as this avoids
needing to do devm memory allocation in component/master binds, then I
can check for NULL when accessing and clear the pointer on
master_unbind to avoid calling to a removed device driver.
(snip)
> > +struct cd01_list {
> > + struct capdata01 **data;
> > + int count;
> > +};
>
> In order to save memory you could try something like this:
>
> struct cd01_list {
> size_t count;
> struct capdata01 data[];
> };
>
> This way you
>
> 1. Avoid the memory fragmentation resulting from multiple memory allocations.
>
> 2. Omit two pointers when accessing the data.
>
> You can use struct_size() from linux/overflow.h to calculate the size of such
> an array with a trailing flexible array.
>
> Thanks,
> Armin Wolf
>
I think I have this part working in my branch. Using devm_kzalloc also
allows me to omit manually setting NULL in a few cases, which is
cleaner. Is it preferred to use struct_size() directly in the
devm_kzalloc call, or create a separate `size` variable to set the
result to and pass that into the function?
- Derek
> > +
> > +int lwmi_cd01_match(struct device *dev, void *data);
> > +
> > +#endif /* !_LENOVO_WMI_CAPDATA01_H_ */
