- * comedi_dio_insn_config() - boilerplate (*insn_config) for DIO subdevices.
- * @dev: comedi_device struct
- * @s: comedi_subdevice struct
- * @insn: comedi_insn struct
- * @data: parameters for the @insn
- * @mask: io_bits mask for grouped channels
+ * comedi_dio_insn_config() - Boilerplate (*insn_config) for DIO subdevices
+ * @dev: COMEDI device.
+ * @s: COMEDI subdevice.
+ * @insn: COMEDI instruction.
+ * @data: Instruction parameters and return data.
+ * @mask: io_bits mask for grouped channels, or 0 for single channel.
+ *
+ * If @mask is 0, it is replaced with a single-bit mask corresponding to the
+ * channel number specified by @insn->chanspec. Otherwise, @mask
+ * corresponds to a group of channels (which should include the specified
+ * channel) that are always configured together as inputs or outputs.
+ *
+ * Partially handles the %INSN_CONFIG_DIO_INPUT, %INSN_CONFIG_DIO_OUTPUTS,
+ * and %INSN_CONFIG_DIO_QUERY instructions. The first two update
+ * @s->io_bits to record the directions of the masked channels. The last
+ * one sets @data[1] to the current direction of the group of channels
+ * (%COMEDI_INPUT) or %COMEDI_OUTPUT) as recorded in @s->io_bits.
+ *
+ * The caller is responsible for updating the DIO direction in the hardware
+ * registers if this function returns 0.
+ *
+ * Returns 0 for a %INSN_CONFIG_DIO_INPUT or %INSN_CONFIG_DIO_OUTPUT
+ * instruction, @insn->n (> 0) for a %INSN_CONFIG_DIO_QUERY instruction, or
+ * -EINVAL for some other instruction.