max6650.rst 2.3 KB

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  1. Kernel driver max6650
  2. =====================
  3. Supported chips:
  4. * Maxim MAX6650
  5. Prefix: 'max6650'
  6. Addresses scanned: none
  7. Datasheet: http://pdfserv.maxim-ic.com/en/ds/MAX6650-MAX6651.pdf
  8. * Maxim MAX6651
  9. Prefix: 'max6651'
  10. Addresses scanned: none
  11. Datasheet: http://pdfserv.maxim-ic.com/en/ds/MAX6650-MAX6651.pdf
  12. Authors:
  13. - Hans J. Koch <hjk@hansjkoch.de>
  14. - John Morris <john.morris@spirentcom.com>
  15. - Claus Gindhart <claus.gindhart@kontron.com>
  16. Description
  17. -----------
  18. This driver implements support for the Maxim MAX6650 and MAX6651.
  19. The 2 devices are very similar, but the MAX6550 has a reduced feature
  20. set, e.g. only one fan-input, instead of 4 for the MAX6651.
  21. The driver is not able to distinguish between the 2 devices.
  22. The driver provides the following sensor accesses in sysfs:
  23. =============== ======= =======================================================
  24. fan1_input ro fan tachometer speed in RPM
  25. fan2_input ro "
  26. fan3_input ro "
  27. fan4_input ro "
  28. fan1_target rw desired fan speed in RPM (closed loop mode only)
  29. pwm1_enable rw regulator mode, 0=full on, 1=open loop, 2=closed loop
  30. 3=off
  31. pwm1 rw relative speed (0-255), 255=max. speed.
  32. Used in open loop mode only.
  33. fan1_div rw sets the speed range the inputs can handle. Legal
  34. values are 1, 2, 4, and 8. Use lower values for
  35. faster fans.
  36. =============== ======= =======================================================
  37. Usage notes
  38. -----------
  39. This driver does not auto-detect devices. You will have to instantiate the
  40. devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
  41. details.
  42. Module parameters
  43. -----------------
  44. If your board has a BIOS that initializes the MAX6650/6651 correctly, you can
  45. simply load your module without parameters. It won't touch the configuration
  46. registers then. If your board BIOS doesn't initialize the chip, or you want
  47. different settings, you can set the following parameters:
  48. voltage_12V: 5=5V fan, 12=12V fan, 0=don't change
  49. prescaler: Possible values are 1,2,4,8,16, or 0 for don't change
  50. clock: The clock frequency in Hz of the chip the driver should assume [254000]
  51. Please have a look at the MAX6650/6651 data sheet and make sure that you fully
  52. understand the meaning of these parameters before you attempt to change them.