ltc4261.rst 2.2 KB

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  1. Kernel driver ltc4261
  2. =====================
  3. Supported chips:
  4. * Linear Technology LTC4261
  5. Prefix: 'ltc4261'
  6. Addresses scanned: -
  7. Datasheet:
  8. http://cds.linear.com/docs/Datasheet/42612fb.pdf
  9. Author: Guenter Roeck <linux@roeck-us.net>
  10. Description
  11. -----------
  12. The LTC4261/LTC4261-2 negative voltage Hot Swap controllers allow a board
  13. to be safely inserted and removed from a live backplane.
  14. Usage Notes
  15. -----------
  16. This driver does not probe for LTC4261 devices, since there is no register
  17. which can be safely used to identify the chip. You will have to instantiate
  18. the devices explicitly.
  19. Example: the following will load the driver for an LTC4261 at address 0x10
  20. on I2C bus #1::
  21. $ modprobe ltc4261
  22. $ echo ltc4261 0x10 > /sys/bus/i2c/devices/i2c-1/new_device
  23. Sysfs entries
  24. -------------
  25. Voltage readings provided by this driver are reported as obtained from the ADC
  26. registers. If a set of voltage divider resistors is installed, calculate the
  27. real voltage by multiplying the reported value with (R1+R2)/R2, where R1 is the
  28. value of the divider resistor against the measured voltage and R2 is the value
  29. of the divider resistor against Ground.
  30. Current reading provided by this driver is reported as obtained from the ADC
  31. Current Sense register. The reported value assumes that a 1 mOhm sense resistor
  32. is installed. If a different sense resistor is installed, calculate the real
  33. current by dividing the reported value by the sense resistor value in mOhm.
  34. The chip has two voltage sensors, but only one set of voltage alarm status bits.
  35. In many many designs, those alarms are associated with the ADIN2 sensor, due to
  36. the proximity of the ADIN2 pin to the OV pin. ADIN2 is, however, not available
  37. on all chip variants. To ensure that the alarm condition is reported to the user,
  38. report it with both voltage sensors.
  39. ======================= =============================
  40. in1_input ADIN2 voltage (mV)
  41. in1_min_alarm ADIN/ADIN2 Undervoltage alarm
  42. in1_max_alarm ADIN/ADIN2 Overvoltage alarm
  43. in2_input ADIN voltage (mV)
  44. in2_min_alarm ADIN/ADIN2 Undervoltage alarm
  45. in2_max_alarm ADIN/ADIN2 Overvoltage alarm
  46. curr1_input SENSE current (mA)
  47. curr1_alarm SENSE overcurrent alarm
  48. ======================= =============================