userio.rst 2.9 KB

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  1. .. include:: <isonum.txt>
  2. ===================
  3. The userio Protocol
  4. ===================
  5. :Copyright: |copy| 2015 Stephen Chandler Paul <thatslyude@gmail.com>
  6. Sponsored by Red Hat
  7. Introduction
  8. =============
  9. This module is intended to try to make the lives of input driver developers
  10. easier by allowing them to test various serio devices (mainly the various
  11. touchpads found on laptops) without having to have the physical device in front
  12. of them. userio accomplishes this by allowing any privileged userspace program
  13. to directly interact with the kernel's serio driver and control a virtual serio
  14. port from there.
  15. Usage overview
  16. ==============
  17. In order to interact with the userio kernel module, one simply opens the
  18. /dev/userio character device in their applications. Commands are sent to the
  19. kernel module by writing to the device, and any data received from the serio
  20. driver is read as-is from the /dev/userio device. All of the structures and
  21. macros you need to interact with the device are defined in <linux/userio.h> and
  22. <linux/serio.h>.
  23. Command Structure
  24. =================
  25. The struct used for sending commands to /dev/userio is as follows::
  26. struct userio_cmd {
  27. __u8 type;
  28. __u8 data;
  29. };
  30. ``type`` describes the type of command that is being sent. This can be any one
  31. of the USERIO_CMD macros defined in <linux/userio.h>. ``data`` is the argument
  32. that goes along with the command. In the event that the command doesn't have an
  33. argument, this field can be left untouched and will be ignored by the kernel.
  34. Each command should be sent by writing the struct directly to the character
  35. device. In the event that the command you send is invalid, an error will be
  36. returned by the character device and a more descriptive error will be printed
  37. to the kernel log. Only one command can be sent at a time, any additional data
  38. written to the character device after the initial command will be ignored.
  39. To close the virtual serio port, just close /dev/userio.
  40. Commands
  41. ========
  42. USERIO_CMD_REGISTER
  43. ~~~~~~~~~~~~~~~~~~~
  44. Registers the port with the serio driver and begins transmitting data back and
  45. forth. Registration can only be performed once a port type is set with
  46. USERIO_CMD_SET_PORT_TYPE. Has no argument.
  47. USERIO_CMD_SET_PORT_TYPE
  48. ~~~~~~~~~~~~~~~~~~~~~~~~
  49. Sets the type of port we're emulating, where ``data`` is the port type being
  50. set. Can be any of the macros from <linux/serio.h>. For example: SERIO_8042
  51. would set the port type to be a normal PS/2 port.
  52. USERIO_CMD_SEND_INTERRUPT
  53. ~~~~~~~~~~~~~~~~~~~~~~~~~
  54. Sends an interrupt through the virtual serio port to the serio driver, where
  55. ``data`` is the interrupt data being sent.
  56. Userspace tools
  57. ===============
  58. The userio userspace tools are able to record PS/2 devices using some of the
  59. debugging information from i8042, and play back the devices on /dev/userio. The
  60. latest version of these tools can be found at:
  61. https://github.com/Lyude/ps2emu