omap-hdq 1.8 KB

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  1. Kernel driver for omap HDQ/1-wire module.
  2. ========================================
  3. Supported chips:
  4. ================
  5. HDQ/1-wire controller on the TI OMAP 2430/3430 platforms.
  6. A useful link about HDQ basics:
  7. ===============================
  8. http://focus.ti.com/lit/an/slua408a/slua408a.pdf
  9. Description:
  10. ============
  11. The HDQ/1-Wire module of TI OMAP2430/3430 platforms implement the hardware
  12. protocol of the master functions of the Benchmark HDQ and the Dallas
  13. Semiconductor 1-Wire protocols. These protocols use a single wire for
  14. communication between the master (HDQ/1-Wire controller) and the slave
  15. (HDQ/1-Wire external compliant device).
  16. A typical application of the HDQ/1-Wire module is the communication with battery
  17. monitor (gas gauge) integrated circuits.
  18. The controller supports operation in both HDQ and 1-wire mode. The essential
  19. difference between the HDQ and 1-wire mode is how the slave device responds to
  20. initialization pulse.In HDQ mode, the firmware does not require the host to
  21. create an initialization pulse to the slave.However, the slave can be reset by
  22. using an initialization pulse (also referred to as a break pulse).The slave
  23. does not respond with a presence pulse as it does in the 1-Wire protocol.
  24. Remarks:
  25. ========
  26. The driver (drivers/w1/masters/omap_hdq.c) supports the HDQ mode of the
  27. controller. In this mode, as we can not read the ID which obeys the W1
  28. spec(family:id:crc), a module parameter can be passed to the driver which will
  29. be used to calculate the CRC and pass back an appropriate slave ID to the W1
  30. core.
  31. By default the master driver and the BQ slave i/f
  32. driver(drivers/w1/slaves/w1_bq27000.c) sets the ID to 1.
  33. Please note to load both the modules with a different ID if required, but note
  34. that the ID used should be same for both master and slave driver loading.
  35. e.g:
  36. insmod omap_hdq.ko W1_ID=2
  37. inamod w1_bq27000.ko F_ID=2