Hi Vishnu,
On Mon, Sep 01, 2025 at 10:53:05PM +0900, Vishnu Sankar wrote:
> Add support for enabling and disabling doubletap on TrackPoint devices
> that support this functionality. The feature is detected using firmware
> ID and exposed via sysfs as `doubletap_enabled`.
>
> The feature is only available on newer ThinkPads (2023 and later).The driver
> exposes this capability via a new sysfs attribute:
> "/sys/bus/serio/devices/seriox/doubletap_enabled".
>
> The attribute is only created if the device is detected to be capable of
> doubletap via firmware and variant ID checks. This functionality will be
> used by platform drivers such as thinkpad_acpi to expose and control doubletap
> via user interfaces.
>
> Signed-off-by: Vishnu Sankar <[email protected]>
> Suggested-by: Mark Pearson <[email protected]>
> Suggested-by: Dmitry Torokhov <[email protected]>
> ---
> Changes in v2:
> - Improve commit messages
> - Sysfs attributes moved to trackpoint.c
> - Removed unnecessary comments
> - Removed unnecessary debug messages
> - Using strstarts() instead of strcmp()
> - is_trackpoint_dt_capable() modified
> - Removed _BIT suffix and used BIT() define.
> - Reverse the trackpoint_doubletap_status() logic to return error first.
> - Removed export functions as a result of the design change
> - Changed trackpoint_dev->psmouse to parent_psmouse
> - The path of trackpoint.h is not changed.
> Changes in v3:
> - No changes.
> ---
> drivers/input/mouse/trackpoint.c | 149 +++++++++++++++++++++++++++++++
> drivers/input/mouse/trackpoint.h | 15 ++++
> 2 files changed, 164 insertions(+)
>
> diff --git a/drivers/input/mouse/trackpoint.c
> b/drivers/input/mouse/trackpoint.c
> index 5f6643b69a2c..c6f17b0dec3a 100644
> --- a/drivers/input/mouse/trackpoint.c
> +++ b/drivers/input/mouse/trackpoint.c
> @@ -16,6 +16,8 @@
> #include "psmouse.h"
> #include "trackpoint.h"
>
> +static struct trackpoint_data *trackpoint_dev;
Please do not use globals.
> +
> static const char * const trackpoint_variants[] = {
> [TP_VARIANT_IBM] = "IBM",
> [TP_VARIANT_ALPS] = "ALPS",
> @@ -63,6 +65,21 @@ static int trackpoint_write(struct ps2dev *ps2dev, u8 loc,
> u8 val)
> return ps2_command(ps2dev, param, MAKE_PS2_CMD(3, 0, TP_COMMAND));
> }
>
> +/* Read function for TrackPoint extended registers */
> +static int trackpoint_extended_read(struct ps2dev *ps2dev, u8 loc, u8 *val)
> +{
> + u8 ext_param[2] = {TP_READ_MEM, loc};
> + int error;
> +
> + error = ps2_command(ps2dev,
> + ext_param, MAKE_PS2_CMD(2, 1, TP_COMMAND));
> +
> + if (!error)
> + *val = ext_param[0];
> +
> + return error;
> +}
> +
> static int trackpoint_toggle_bit(struct ps2dev *ps2dev, u8 loc, u8 mask)
> {
> u8 param[3] = { TP_TOGGLE, loc, mask };
> @@ -393,6 +410,131 @@ static int trackpoint_reconnect(struct psmouse *psmouse)
> return 0;
> }
>
> +/* List of known incapable device PNP IDs */
> +static const char * const dt_incompatible_devices[] = {
> + "LEN0304",
> + "LEN0306",
> + "LEN0317",
> + "LEN031A",
> + "LEN031B",
> + "LEN031C",
> + "LEN031D",
> +};
> +
> +/*
> + * checks if it’s a doubletap capable device
> + * The PNP ID format eg: is "PNP: LEN030d PNP0f13".
> + */
> +static bool is_trackpoint_dt_capable(const char *pnp_id)
> +{
> + const char *id_start;
> + char id[8];
> +
> + if (!strstarts(pnp_id, "PNP: LEN03"))
> + return false;
> +
> + /* Points to "LEN03xxxx" */
> + id_start = pnp_id + 5;
> + if (sscanf(id_start, "%7s", id) != 1)
> + return false;
> +
> + /* Check if it's blacklisted */
> + for (size_t i = 0; i < ARRAY_SIZE(dt_incompatible_devices); ++i) {
> + if (strcmp(id, dt_incompatible_devices[i]) == 0)
> + return false;
> + }
> + return true;
> +}
> +
> +/* Trackpoint doubletap status function */
> +static int trackpoint_doubletap_status(bool *status)
> +{
> + struct trackpoint_data *tp = trackpoint_dev;
> + struct ps2dev *ps2dev = &tp->parent_psmouse->ps2dev;
> + u8 reg_val;
> + int rc;
> +
> + /* Reading the Doubletap register using extended read */
> + rc = trackpoint_extended_read(ps2dev, TP_DOUBLETAP, ®_val);
> + if (rc)
> + return rc;
> +
> + *status = reg_val & TP_DOUBLETAP_STATUS ? true : false;
> +
> + return 0;
> +}
> +
> +/* Trackpoint doubletap enable/disable function */
> +static int trackpoint_set_doubletap(bool enable)
> +{
> + struct trackpoint_data *tp = trackpoint_dev;
> + struct ps2dev *ps2dev = &tp->parent_psmouse->ps2dev;
> + static u8 doubletap_state;
> + u8 new_val;
> +
> + if (!tp)
> + return -ENODEV;
> +
> + new_val = enable ? TP_DOUBLETAP_ENABLE : TP_DOUBLETAP_DISABLE;
> +
> + if (doubletap_state == new_val)
> + return 0;
> +
> + doubletap_state = new_val;
> +
> + return trackpoint_write(ps2dev, TP_DOUBLETAP, new_val);
> +}
> +
> +/*
> + * Trackpoint Doubletap Interface
> + * Control/Monitoring of Trackpoint Doubletap from:
> + * /sys/bus/serio/devices/seriox/doubletap_enabled
> + */
> +static ssize_t doubletap_enabled_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct serio *serio = to_serio_port(dev);
> + struct psmouse *psmouse = psmouse_from_serio(serio);
> + struct trackpoint_data *tp = psmouse->private;
> + bool status;
> + int rc;
> +
> + if (!tp || !tp->doubletap_capable)
> + return -ENODEV;
> +
> + rc = trackpoint_doubletap_status(&status);
> + if (rc)
> + return rc;
> +
> + return sysfs_emit(buf, "%d\n", status ? 1 : 0);
> +}
> +
> +static ssize_t doubletap_enabled_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct serio *serio = to_serio_port(dev);
> + struct psmouse *psmouse = psmouse_from_serio(serio);
> + struct trackpoint_data *tp = psmouse->private;
> + bool enable;
> + int err;
> +
> + if (!tp || !tp->doubletap_capable)
> + return -ENODEV;
> +
> + err = kstrtobool(buf, &enable);
> + if (err)
> + return err;
> +
> + err = trackpoint_set_doubletap(enable);
> + if (err)
> + return err;
> +
> + return count;
> +}
> +
> +static DEVICE_ATTR_RW(doubletap_enabled);
> +
> int trackpoint_detect(struct psmouse *psmouse, bool set_properties)
> {
> struct ps2dev *ps2dev = &psmouse->ps2dev;
> @@ -425,6 +567,9 @@ int trackpoint_detect(struct psmouse *psmouse, bool
> set_properties)
> psmouse->reconnect = trackpoint_reconnect;
> psmouse->disconnect = trackpoint_disconnect;
>
> + trackpoint_dev = psmouse->private;
> + trackpoint_dev->parent_psmouse = psmouse;
> +
> if (variant_id != TP_VARIANT_IBM) {
> /* Newer variants do not support extended button query. */
> button_info = 0x33;
> @@ -470,6 +615,10 @@ int trackpoint_detect(struct psmouse *psmouse, bool
> set_properties)
> psmouse->vendor, firmware_id,
> (button_info & 0xf0) >> 4, button_info & 0x0f);
>
> + tp->doubletap_capable =
> is_trackpoint_dt_capable(ps2dev->serio->firmware_id);
> + if (tp->doubletap_capable)
> + device_create_file(&psmouse->ps2dev.serio->dev,
> &dev_attr_doubletap_enabled);
Please use existing facilities in psmouse driver to define and register
protocol-specific attributes. Use is_visible() to control whether the
attribute is accessible or not.
Thanks.
--
Dmitry
_______________________________________________
ibm-acpi-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/ibm-acpi-devel
