Load acpi_iichid and make sure to have an I2C controller driver (e.g. ig4) loaded beforehand. acpi_iichid should require iicbus and iichid as dependencies.
After loading you should see something like this (That is the output on my Dell Latitude 5480):
iichid_acpi0: <HID over I2C (ACPI)> irq 51 on acpi0
iichid_acpi0: descriptor register address is 20
iichid_acpi0: parent device is "\134_SB_.PCI0.I2C1"
iichid0: <HID over I2C> at addr 0x2c on iicbus1
iichid0: ADDR 0x2c REG 0x20
iichid0: 3 buttons and [XYZT] coordinates ID=1
iichid0: 3 buttons and [XYZT] coordinates ID=1
iichid0: determined (len=81) and described (len=83) input report lengths mismatch
iichid_acpi0: added iichid0 ADDR 0x2c REG 0x20 to iicbus1
iichid_acpi0: allocated irq at 0xfffff80004a46600 and rid 0
iichid_acpi0: successfully setup interrupt