lm87.rst 3.0 KB

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  1. Kernel driver lm87
  2. ==================
  3. Supported chips:
  4. * National Semiconductor LM87
  5. Prefix: 'lm87'
  6. Addresses scanned: I2C 0x2c - 0x2e
  7. Datasheet: http://www.national.com/pf/LM/LM87.html
  8. * Analog Devices ADM1024
  9. Prefix: 'adm1024'
  10. Addresses scanned: I2C 0x2c - 0x2e
  11. Datasheet: https://www.analog.com/en/prod/0,2877,ADM1024,00.html
  12. Authors:
  13. - Frodo Looijaard <frodol@dds.nl>,
  14. - Philip Edelbrock <phil@netroedge.com>,
  15. - Mark Studebaker <mdsxyz123@yahoo.com>,
  16. - Stephen Rousset <stephen.rousset@rocketlogix.com>,
  17. - Dan Eaton <dan.eaton@rocketlogix.com>,
  18. - Jean Delvare <jdelvare@suse.de>,
  19. - Original 2.6 port Jeff Oliver
  20. Description
  21. -----------
  22. This driver implements support for the National Semiconductor LM87
  23. and the Analog Devices ADM1024.
  24. The LM87 implements up to three temperature sensors, up to two fan
  25. rotation speed sensors, up to seven voltage sensors, alarms, and some
  26. miscellaneous stuff. The ADM1024 is fully compatible.
  27. Temperatures are measured in degrees Celsius. Each input has a high
  28. and low alarm settings. A high limit produces an alarm when the value
  29. goes above it, and an alarm is also produced when the value goes below
  30. the low limit.
  31. Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
  32. triggered if the rotation speed has dropped below a programmable limit. Fan
  33. readings can be divided by a programmable divider (1, 2, 4 or 8) to give
  34. the readings more range or accuracy. Not all RPM values can accurately be
  35. represented, so some rounding is done. With a divider of 2, the lowest
  36. representable value is around 2600 RPM.
  37. Voltage sensors (also known as IN sensors) report their values in
  38. volts. An alarm is triggered if the voltage has crossed a programmable
  39. minimum or maximum limit. Note that minimum in this case always means
  40. 'closest to zero'; this is important for negative voltage measurements.
  41. If an alarm triggers, it will remain triggered until the hardware register
  42. is read at least once. This means that the cause for the alarm may
  43. already have disappeared! Note that in the current implementation, all
  44. hardware registers are read whenever any data is read (unless it is less
  45. than 1.0 seconds since the last update). This means that you can easily
  46. miss once-only alarms.
  47. The lm87 driver only updates its values each 1.0 seconds; reading it more
  48. often will do no harm, but will return 'old' values.
  49. Hardware Configurations
  50. -----------------------
  51. The LM87 has four pins which can serve one of two possible functions,
  52. depending on the hardware configuration.
  53. Some functions share pins, so not all functions are available at the same
  54. time. Which are depends on the hardware setup. This driver normally
  55. assumes that firmware configured the chip correctly. Where this is not
  56. the case, platform code must set the I2C client's platform_data to point
  57. to a u8 value to be written to the channel register.
  58. For reference, here is the list of exclusive functions:
  59. - in0+in5 (default) or temp3
  60. - fan1 (default) or in6
  61. - fan2 (default) or in7
  62. - VID lines (default) or IRQ lines (not handled by this driver)