On Tue, Mar 4, 2025, at 9:33 PM, Nitin Joshi wrote:
> Some Thinkpad products support Human Presence Detection (HPD) features.
> Add new sysfs entry so that userspace can determine if feature is
> supported or not.
>
> Reviewed-by: Mark Pearson <mpearson-len...@squebb.ca>
Just in case we're breaking protocol - I have reviewed this off mailing list
with Nitin and gave it the thumbs up. The tag is correct.
Mark
> Signed-off-by: Nitin Joshi <nitjo...@gmail.com>
> ---
> .../admin-guide/laptops/thinkpad-acpi.rst | 20 +++++
> drivers/platform/x86/thinkpad_acpi.c | 79 +++++++++++++++++++
> 2 files changed, 99 insertions(+)
>
> diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> index 4ab0fef7d440..02e6c4306f90 100644
> --- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> +++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst
> @@ -1576,6 +1576,26 @@ percentage level, above which charging will stop.
> The exact semantics of the attributes may be found in
> Documentation/ABI/testing/sysfs-class-power.
>
> +User Presence Sensing Detection
> +------
> +
> +sysfs: hpd_bios_enabled
> +
> +Some Thinkpad products support Human Presence Detection (HPD) features.
> +Added new sysfs entry so that userspace can determine if feature related to
> +HPD should be enabled or disabled.
> +
> +The available commands are::
> +
> + cat /sys/devices/platform/thinkpad_acpi/hpd_bios_enabled
> +
> +BIOS status is mentioned as below:
> +- 0 = Disable
> +- 1 = Enable
> +
> +The property is read-only. If the platform doesn't have support the sysfs
> +class is not created.
> +
> Multiple Commands, Module Parameters
> ------------------------------------
>
> diff --git a/drivers/platform/x86/thinkpad_acpi.c
> b/drivers/platform/x86/thinkpad_acpi.c
> index 72a10ed2017c..daf31b2a4c73 100644
> --- a/drivers/platform/x86/thinkpad_acpi.c
> +++ b/drivers/platform/x86/thinkpad_acpi.c
> @@ -11039,6 +11039,80 @@ static const struct attribute_group
> auxmac_attr_group = {
> .attrs = auxmac_attributes,
> };
>
> +/*************************************************************************
> + * CHPD subdriver, for the Lenovo Human Presence Detection feature.
> + */
> +#define CHPD_GET_SENSOR_STATUS 0x00200000
> +#define CHPD_GET_BIOS_UI_STATUS 0x00100000
> +
> +static bool has_user_presence_sensing;
> +static int hpd_bios_status;
> +static int chpd_command(int command, int *output)
> +{
> + acpi_handle chpd_handle;
> +
> + if (ACPI_FAILURE(acpi_get_handle(hkey_handle, "CHPD", &chpd_handle))) {
> + /* Platform doesn't support CHPD */
> + return -ENODEV;
> + }
> +
> + if (!acpi_evalf(chpd_handle, output, NULL, "dd", command))
> + return -EIO;
> +
> + return 0;
> +}
> +
> +/* sysfs hpd bios status */
> +static ssize_t hpd_bios_enabled_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + return sysfs_emit(buf, "%d\n", hpd_bios_status);
> +}
> +static DEVICE_ATTR_RO(hpd_bios_enabled);
> +
> +static struct attribute *chpd_attributes[] = {
> + &dev_attr_hpd_bios_enabled.attr,
> + NULL
> +};
> +
> +static umode_t chpd_attr_is_visible(struct kobject *kobj,
> + struct attribute *attr, int n)
> +{
> + return has_user_presence_sensing ? attr->mode : 0;
> +}
> +
> +static const struct attribute_group chpd_attr_group = {
> + .is_visible = chpd_attr_is_visible,
> + .attrs = chpd_attributes,
> +};
> +
> +static int tpacpi_chpd_init(struct ibm_init_struct *iibm)
> +{
> + int err, output;
> +
> + err = chpd_command(CHPD_GET_SENSOR_STATUS, &output);
> + if (err)
> + return err;
> +
> + if (output == 1)
> + return -ENODEV;
> +
> + has_user_presence_sensing = true;
> + /* Get User Presence Sensing BIOS status */
> + err = chpd_command(CHPD_GET_BIOS_UI_STATUS, &output);
> + if (err)
> + return err;
> +
> + hpd_bios_status = (output >> 1) & BIT(0);
> +
> + return err;
> +}
> +
> +static struct ibm_struct chpd_driver_data = {
> + .name = "chpd",
> +};
> +
> /* --------------------------------------------------------------------- */
>
> static struct attribute *tpacpi_driver_attributes[] = {
> @@ -11098,6 +11172,7 @@ static const struct attribute_group *tpacpi_groups[]
> = {
> &kbdlang_attr_group,
> &dprc_attr_group,
> &auxmac_attr_group,
> + &chpd_attr_group,
> NULL,
> };
>
> @@ -11694,6 +11769,10 @@ static struct ibm_init_struct ibms_init[]
> __initdata = {
> .init = auxmac_init,
> .data = &auxmac_data,
> },
> + {
> + .init = tpacpi_chpd_init,
> + .data = &chpd_driver_data,
> + },
> };
>
> static int __init set_ibm_param(const char *val, const struct kernel_param
> *kp)
> --
> 2.43.0
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