Re: [PATCH v5 1/2] platform/x86: thinkpad_acpi: Add support to detect hardware damage detection capability.

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

On Wed, 17 Dec 2025, Nitin Joshi wrote:

> Thinkpads are adding the ability to detect and report hardware damage
> status. Add new sysfs interface to identify whether hardware damage
> is detected or not.
> 
> Initial support is available for the USB-C replaceable connector.
> 
> Reviewed-by: Mark Pearson <mpearson-lenovo@squebb.ca>
> Signed-off-by: Nitin Joshi<nitjoshi@gmail.com>
> ---
> Changes since v1:
> -Split patch between hwdd_status and hwdd_detail
> -Incorporated review comments
> Changes since v2:
> -Control visibility of the sysfs attribute based upon ucdd_supported
> Changes since v3:
> -Fix documentation build warning
> Changes since v4:
> -Removed extra line
> ---
>  .../admin-guide/laptops/thinkpad-acpi.rst     |  21 ++++
>  drivers/platform/x86/lenovo/thinkpad_acpi.c   | 105 ++++++++++++++++++
>  2 files changed, 126 insertions(+)
> 
> diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> index 4ab0fef7d440..2db05f718b11 100644
> --- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> +++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> @@ -54,6 +54,7 @@ detailed description):
>  	- Setting keyboard language
>  	- WWAN Antenna type
>  	- Auxmac
> +	- Hardware damage detection capability
>  
>  A compatibility table by model and feature is maintained on the web
>  site, http://ibm-acpi.sf.net/. I appreciate any success or failure
> @@ -1576,6 +1577,26 @@ percentage level, above which charging will stop.
>  The exact semantics of the attributes may be found in
>  Documentation/ABI/testing/sysfs-class-power.
>  
> +Hardware damage detection capability
> +------------------------------------
> +
> +sysfs attributes: hwdd_status
> +
> +Thinkpads are adding the ability to detect and report hardware damage.
> +Add new sysfs interface to identify the damaged device status.
> +Initial support is available for the USB-C replaceable connector.
> +
> +The command to check device damaged status is::
> +
> +        cat /sys/devices/platform/thinkpad_acpi/hwdd_status
> +
> +This value displays status of device damaged
> +- 0 = Not Damaged
> +- 1 = Damaged
> +
> +The property is read-only. If feature is not supported then sysfs
> +attribute is not created.
> +
>  Multiple Commands, Module Parameters
>  ------------------------------------
>  
> diff --git a/drivers/platform/x86/lenovo/thinkpad_acpi.c b/drivers/platform/x86/lenovo/thinkpad_acpi.c
> index cc19fe520ea9..cb1f6dae9334 100644
> --- a/drivers/platform/x86/lenovo/thinkpad_acpi.c
> +++ b/drivers/platform/x86/lenovo/thinkpad_acpi.c
> @@ -11080,6 +11080,106 @@ static const struct attribute_group auxmac_attr_group = {
>  	.attrs = auxmac_attributes,
>  };
>  
> +/*************************************************************************
> + * HWDD subdriver, for the Lenovo Hardware Damage Detection feature.
> + */
> +
> +#define HWDD_GET_DMG_USBC	0x80000001
> +#define HWDD_GET_CAP		0
> +#define HWDD_NOT_SUPPORTED	BIT(31)
> +#define HWDD_SUPPORT_USBC	BIT(0)
> +
> +#define PORT_STATUS		GENMASK(7, 4)
> +#define NUM_PORTS		4
> +
> +static bool hwdd_support_available;
> +static bool ucdd_supported;
> +
> +static int hwdd_command(int command, int *output)
> +{
> +	acpi_handle hwdd_handle;
> +
> +	if (ACPI_FAILURE(acpi_get_handle(hkey_handle, "HWDD", &hwdd_handle)))
> +		return -ENODEV;
> +
> +	if (!acpi_evalf(hwdd_handle, output, NULL, "dd", command))
> +		return -EIO;
> +
> +	return 0;
> +}
> +
> +/* sysfs type-c damage detection capability */
> +static ssize_t hwdd_status_show(struct device *dev,
> +				struct device_attribute *attr,
> +				char *buf)
> +{
> +	unsigned int damage_status, port_status;
> +	int err, i;
> +
> +	if (ucdd_supported) {
> +		/* Get USB TYPE-C damage status */
> +		err = hwdd_command(HWDD_GET_DMG_USBC, &damage_status);
> +		if (err)
> +			return err;
> +
> +		port_status = FIELD_GET(PORT_STATUS, damage_status);
> +		for (i = 0; i < NUM_PORTS; i++) {
> +			if (!(damage_status & BIT(i)))
> +				continue;
> +			if (port_status & BIT(i))
> +				return sysfs_emit(buf, "1\n");
> +		}
> +	} else
> +		return -ENODEV;

The usual approach is to first check not supported + return errno, then 
you don't even need "else". The same comment to the other patch.

-- 
 i.


> +
> +	return sysfs_emit(buf, "0\n");
> +}
> +static DEVICE_ATTR_RO(hwdd_status);
> +
> +static struct attribute *hwdd_attributes[] = {
> +	&dev_attr_hwdd_status.attr,
> +	NULL
> +};
> +
> +static umode_t hwdd_attr_is_visible(struct kobject *kobj,
> +				struct attribute *attr, int n)
> +{
> +	return hwdd_support_available ? attr->mode : 0;
> +}
> +
> +static const struct attribute_group hwdd_attr_group = {
> +	.is_visible = hwdd_attr_is_visible,
> +	.attrs = hwdd_attributes,
> +};
> +
> +static int tpacpi_hwdd_init(struct ibm_init_struct *iibm)
> +{
> +	int err, output;
> +
> +	/* Below command checks the HWDD damage capability */
> +	err = hwdd_command(HWDD_GET_CAP, &output);
> +	if (err)
> +		return err;
> +
> +	if (!(output & HWDD_NOT_SUPPORTED))
> +		return -ENODEV;
> +
> +	hwdd_support_available = true;
> +
> +	/*
> +	 * BIT(0) is assigned to check capability of damage detection is
> +	 * supported for USB Type-C port or not.
> +	 */
> +	if (output & HWDD_SUPPORT_USBC)
> +		ucdd_supported = true;
> +
> +	return err;
> +}
> +
> +static struct ibm_struct hwdd_driver_data = {
> +	.name = "hwdd",
> +};
> +
>  /* --------------------------------------------------------------------- */
>  
>  static struct attribute *tpacpi_driver_attributes[] = {
> @@ -11139,6 +11239,7 @@ static const struct attribute_group *tpacpi_groups[] = {
>  	&kbdlang_attr_group,
>  	&dprc_attr_group,
>  	&auxmac_attr_group,
> +	&hwdd_attr_group,
>  	NULL,
>  };
>  
> @@ -11752,6 +11853,10 @@ static struct ibm_init_struct ibms_init[] __initdata = {
>  		.init = auxmac_init,
>  		.data = &auxmac_data,
>  	},
> +	{
> +		.init = tpacpi_hwdd_init,
> +		.data = &hwdd_driver_data,
> +	},
>  };
>  
>  static int __init set_ibm_param(const char *val, const struct kernel_param *kp)
>