Re: [PATCH] platform/x86: thinkpad_acpi: Add sysfs to display HWDD raw

[Ilpo Järvinen]

On Tue, 28 Apr 2026, Mark Pearson wrote:

> The Lenovo diagnostics and support team have requested a mechanism
> to get the raw data from the HWDD commands to support customer debug
> situations.
> 
> Add a sysfs entry to display the raw data.
> 
> As it shouldn't be needed in normal operation, add a hwdd_raw_enable
> module parameter for when it is needed

Wouldn't debugfs be more appropriate for things like this? By using it, 
you can avoid adding the module parameter as well.

-- 
 i.

> Signed-off-by: Mark Pearson <mpearson-lenovo@xxxxxxxxx>
> ---
>  drivers/platform/x86/lenovo/thinkpad_acpi.c | 31 +++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> diff --git a/drivers/platform/x86/lenovo/thinkpad_acpi.c b/drivers/platform/x86/lenovo/thinkpad_acpi.c
> index e1cee42a1683..299cc4022e96 100644
> --- a/drivers/platform/x86/lenovo/thinkpad_acpi.c
> +++ b/drivers/platform/x86/lenovo/thinkpad_acpi.c
> @@ -406,6 +406,7 @@ static enum {
>  
>  static int experimental;
>  static u32 dbg_level;
> +static bool hwdd_raw_enable;
>  
>  static struct workqueue_struct *tpacpi_wq;
>  
> @@ -11217,18 +11218,44 @@ static ssize_t hwdd_status_show(struct device *dev,
>  
>  	return sysfs_emit(buf, "0\n");
>  }
> +
> +/* sysfs type-c damage detection raw data */
> +static ssize_t hwdd_raw_show(struct device *dev,
> +			     struct device_attribute *attr,
> +			     char *buf)
> +{
> +	unsigned int damage_status;
> +	int err;
> +
> +	if (!ucdd_supported)
> +		return -ENODEV;
> +
> +	/* Get USB TYPE-C damage status */
> +	err = hwdd_command(HWDD_GET_DMG_USBC, &damage_status);
> +	if (err)
> +		return err;
> +
> +	return sysfs_emit(buf, "0x%x\n", damage_status);
> +}
> +
> +static DEVICE_ATTR_RO(hwdd_raw);
>  static DEVICE_ATTR_RO(hwdd_status);
>  static DEVICE_ATTR_RO(hwdd_detail);
>  
>  static struct attribute *hwdd_attributes[] = {
>  	&dev_attr_hwdd_status.attr,
>  	&dev_attr_hwdd_detail.attr,
> +	&dev_attr_hwdd_raw.attr,
>  	NULL
>  };
>  
>  static umode_t hwdd_attr_is_visible(struct kobject *kobj,
>  				struct attribute *attr, int n)
>  {
> +	/* Only display hwdd_raw if debug option has been set */
> +	if (attr == &dev_attr_hwdd_raw.attr && !hwdd_raw_enable)
> +		return 0;
> +
>  	return hwdd_support_available ? attr->mode : 0;
>  }
>  
> @@ -11956,6 +11983,10 @@ static int __init set_ibm_param(const char *val, const struct kernel_param *kp)
>  	return -EINVAL;
>  }
>  
> +module_param(hwdd_raw_enable, bool, 0444);
> +MODULE_PARM_DESC(hwdd_raw_enable,
> +		 "Enables hwdd raw output sysfs interface");
> +
>  module_param(experimental, int, 0444);
>  MODULE_PARM_DESC(experimental,
>  		 "Enables experimental features when non-zero");
>