Re: [PATCH 1/2] platform/x86: uniwill-laptop: Introduce device descriptor system

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Thu, 4 Dec 2025, Werner Sembach wrote:

> From: Armin Wolf <W_Armin@gmx.de>
> 
> Future additions to the driver will depend on device-specific
> initialization steps. Extend the DMI-based feature detection system
> to include device descriptors. Each descriptor contains a bitmap of
> supported features and a set of callback for performing
> device-specific initialization.
> 
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> Co-developed-by: Werner Sembach <wse@tuxedocomputers.com>
> Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
> ---
>  drivers/platform/x86/uniwill/uniwill-acpi.c | 168 +++++++++++++++++---
>  1 file changed, 142 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/platform/x86/uniwill/uniwill-acpi.c b/drivers/platform/x86/uniwill/uniwill-acpi.c
> index bd7e63dd51810..01192c32608e5 100644
> --- a/drivers/platform/x86/uniwill/uniwill-acpi.c
> +++ b/drivers/platform/x86/uniwill/uniwill-acpi.c
> @@ -322,6 +322,7 @@ struct uniwill_data {
>  	struct device *dev;
>  	acpi_handle handle;
>  	struct regmap *regmap;
> +	unsigned int features;
>  	struct acpi_battery_hook hook;
>  	unsigned int last_charge_ctrl;
>  	struct mutex battery_lock;	/* Protects the list of currently registered batteries */
> @@ -341,12 +342,21 @@ struct uniwill_battery_entry {
>  	struct power_supply *battery;
>  };
>  
> +struct uniwill_device_descriptor {
> +	unsigned int features;
> +	/* Executed during driver probing */
> +	int (*probe)(struct uniwill_data *data);
> +};
> +
>  static bool force;
>  module_param_unsafe(force, bool, 0);
>  MODULE_PARM_DESC(force, "Force loading without checking for supported devices\n");
>  
> -/* Feature bitmask since the associated registers are not reliable */
> -static unsigned int supported_features;
> +/*
> + * Contains device specific data like the feature bitmap since
> + * the associated registers are not always reliable.
> + */
> +static struct uniwill_device_descriptor device_descriptor __ro_after_init;
>  
>  static const char * const uniwill_temp_labels[] = {
>  	"CPU",
> @@ -411,6 +421,13 @@ static const struct key_entry uniwill_keymap[] = {
>  	{ KE_END }
>  };
>  
> +static inline bool uniwill_device_supports(struct uniwill_data *data,
> +					   unsigned int features_mask,
> +					   unsigned int features)
> +{
> +	return (data->features & features_mask) == features;
> +}
> +
>  static int uniwill_ec_reg_write(void *context, unsigned int reg, unsigned int val)
>  {
>  	union acpi_object params[2] = {
> @@ -799,24 +816,31 @@ static struct attribute *uniwill_attrs[] = {
>  
>  static umode_t uniwill_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n)
>  {
> +	struct device *dev = kobj_to_dev(kobj);
> +	struct uniwill_data *data = dev_get_drvdata(dev);
> +
>  	if (attr == &dev_attr_fn_lock_toggle_enable.attr) {
> -		if (supported_features & UNIWILL_FEATURE_FN_LOCK_TOGGLE)
> +		if (uniwill_device_supports(data, UNIWILL_FEATURE_FN_LOCK_TOGGLE,
> +					    UNIWILL_FEATURE_FN_LOCK_TOGGLE))
>  			return attr->mode;
>  	}
>  
>  	if (attr == &dev_attr_super_key_toggle_enable.attr) {
> -		if (supported_features & UNIWILL_FEATURE_SUPER_KEY_TOGGLE)
> +		if (uniwill_device_supports(data, UNIWILL_FEATURE_SUPER_KEY_TOGGLE,
> +					    UNIWILL_FEATURE_SUPER_KEY_TOGGLE))
>  			return attr->mode;
>  	}
>  
>  	if (attr == &dev_attr_touchpad_toggle_enable.attr) {
> -		if (supported_features & UNIWILL_FEATURE_TOUCHPAD_TOGGLE)
> +		if (uniwill_device_supports(data, UNIWILL_FEATURE_TOUCHPAD_TOGGLE,
> +					    UNIWILL_FEATURE_TOUCHPAD_TOGGLE))
>  			return attr->mode;
>  	}
>  
>  	if (attr == &dev_attr_rainbow_animation.attr ||
>  	    attr == &dev_attr_breathing_in_suspend.attr) {
> -		if (supported_features & UNIWILL_FEATURE_LIGHTBAR)
> +		if (uniwill_device_supports(data, UNIWILL_FEATURE_LIGHTBAR,
> +					    UNIWILL_FEATURE_LIGHTBAR))
>  			return attr->mode;
>  	}
>  
> @@ -944,7 +968,8 @@ static int uniwill_hwmon_init(struct uniwill_data *data)
>  {
>  	struct device *hdev;
>  
> -	if (!(supported_features & UNIWILL_FEATURE_HWMON))
> +	if (!uniwill_device_supports(data, UNIWILL_FEATURE_HWMON,
> +				     UNIWILL_FEATURE_HWMON))
>  		return 0;
>  
>  	hdev = devm_hwmon_device_register_with_info(data->dev, "uniwill", data,
> @@ -1019,7 +1044,8 @@ static int uniwill_led_init(struct uniwill_data *data)
>  	unsigned int value;
>  	int ret;
>  
> -	if (!(supported_features & UNIWILL_FEATURE_LIGHTBAR))
> +	if (!uniwill_device_supports(data, UNIWILL_FEATURE_LIGHTBAR,
> +				     UNIWILL_FEATURE_LIGHTBAR))
>  		return 0;
>  
>  	ret = devm_mutex_init(data->dev, &data->led_lock);
> @@ -1232,7 +1258,8 @@ static int uniwill_battery_init(struct uniwill_data *data)
>  {
>  	int ret;
>  
> -	if (!(supported_features & UNIWILL_FEATURE_BATTERY))
> +	if (!uniwill_device_supports(data, UNIWILL_FEATURE_BATTERY,
> +				     UNIWILL_FEATURE_BATTERY))
>  		return 0;
>  
>  	ret = devm_mutex_init(data->dev, &data->battery_lock);
> @@ -1361,6 +1388,19 @@ static int uniwill_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		return ret;
>  
> +	data->features = device_descriptor.features;
> +
> +	/*
> +	 * Some devices might need to perform some device-specific initialization steps
> +	 * before the supported features are initialized. Because of this we have to call
> +	 * this callback just after the EC itself was initialized.
> +	 */
> +	if (device_descriptor.probe) {
> +		ret = device_descriptor.probe(data);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
>  	ret = uniwill_battery_init(data);
>  	if (ret < 0)
>  		return ret;
> @@ -1385,7 +1425,8 @@ static void uniwill_shutdown(struct platform_device *pdev)
>  
>  static int uniwill_suspend_keyboard(struct uniwill_data *data)
>  {
> -	if (!(supported_features & UNIWILL_FEATURE_SUPER_KEY_TOGGLE))
> +	if (!uniwill_device_supports(data, UNIWILL_FEATURE_SUPER_KEY_TOGGLE,
> +				     UNIWILL_FEATURE_SUPER_KEY_TOGGLE))
>  		return 0;
>  
>  	/*
> @@ -1397,7 +1438,8 @@ static int uniwill_suspend_keyboard(struct uniwill_data *data)
>  
>  static int uniwill_suspend_battery(struct uniwill_data *data)
>  {
> -	if (!(supported_features & UNIWILL_FEATURE_BATTERY))
> +	if (!uniwill_device_supports(data, UNIWILL_FEATURE_BATTERY,
> +				     UNIWILL_FEATURE_BATTERY))
>  		return 0;
>  
>  	/*
> @@ -1432,7 +1474,8 @@ static int uniwill_resume_keyboard(struct uniwill_data *data)
>  	unsigned int value;
>  	int ret;
>  
> -	if (!(supported_features & UNIWILL_FEATURE_SUPER_KEY_TOGGLE))
> +	if (!uniwill_device_supports(data, UNIWILL_FEATURE_SUPER_KEY_TOGGLE,
> +				     UNIWILL_FEATURE_SUPER_KEY_TOGGLE))
>  		return 0;
>  
>  	ret = regmap_read(data->regmap, EC_ADDR_SWITCH_STATUS, &value);
> @@ -1448,7 +1491,8 @@ static int uniwill_resume_keyboard(struct uniwill_data *data)
>  
>  static int uniwill_resume_battery(struct uniwill_data *data)
>  {
> -	if (!(supported_features & UNIWILL_FEATURE_BATTERY))
> +	if (!uniwill_device_supports(data, UNIWILL_FEATURE_BATTERY,
> +				     UNIWILL_FEATURE_BATTERY))
>  		return 0;
>  
>  	return regmap_update_bits(data->regmap, EC_ADDR_CHARGE_CTRL, CHARGE_CTRL_MASK,
> @@ -1496,6 +1540,25 @@ static struct platform_driver uniwill_driver = {
>  	.shutdown = uniwill_shutdown,
>  };
>  
> +static struct uniwill_device_descriptor lapac71h_descriptor __initdata = {
> +	.features = UNIWILL_FEATURE_FN_LOCK_TOGGLE |
> +		    UNIWILL_FEATURE_SUPER_KEY_TOGGLE |
> +		    UNIWILL_FEATURE_TOUCHPAD_TOGGLE |
> +		    UNIWILL_FEATURE_BATTERY |
> +		    UNIWILL_FEATURE_HWMON
> +};
> +
> +static struct uniwill_device_descriptor lapkc71f_descriptor __initdata = {
> +	.features = UNIWILL_FEATURE_FN_LOCK_TOGGLE |
> +		    UNIWILL_FEATURE_SUPER_KEY_TOGGLE |
> +		    UNIWILL_FEATURE_TOUCHPAD_TOGGLE |
> +		    UNIWILL_FEATURE_LIGHTBAR |
> +		    UNIWILL_FEATURE_BATTERY |
> +		    UNIWILL_FEATURE_HWMON
> +};
> +
> +static struct uniwill_device_descriptor empty_descriptor __initdata = {};
> +
>  static const struct dmi_system_id uniwill_dmi_table[] __initconst = {
>  	{
>  		.ident = "XMG FUSION 15",
> @@ -1503,6 +1566,7 @@ static const struct dmi_system_id uniwill_dmi_table[] __initconst = {
>  			DMI_MATCH(DMI_SYS_VENDOR, "SchenkerTechnologiesGmbH"),
>  			DMI_EXACT_MATCH(DMI_BOARD_NAME, "LAPQC71A"),
>  		},
> +		.driver_data = &empty_descriptor,

Hi,

Is there some advantage of having an "empty descriptor" over just NULL 
checking its presence in the code?

>  static int __init uniwill_init(void)
>  {
> +	const struct uniwill_device_descriptor *descriptor;
>  	const struct dmi_system_id *id;
>  	int ret;
>  
> @@ -1880,10 +1984,22 @@ static int __init uniwill_init(void)
>  			return -ENODEV;
>  
>  		/* Assume that the device supports all features */
> -		supported_features = UINT_MAX;
> +		device_descriptor.features = UINT_MAX;
>  		pr_warn("Loading on a potentially unsupported device\n");
>  	} else {
> -		supported_features = (uintptr_t)id->driver_data;
> +		/*
> +		 * Some devices might support additional features depending on
> +		 * the BIOS version/date, so we call this callback to let them
> +		 * modify their device descriptor accordingly.
> +		 */
> +		if (id->callback) {
> +			ret = id->callback(id);
> +			if (ret < 0)
> +				return ret;
> +		}
> +
> +		descriptor = id->driver_data;
> +		device_descriptor = *descriptor;
>  	}
>  
>  	ret = platform_driver_register(&uniwill_driver);
> 

-- 
 i.