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64 lines
2.1 KiB
64 lines
2.1 KiB
Kernel driver nsa320_hwmon |
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========================== |
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Supported chips: |
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* Holtek HT46R065 microcontroller with onboard firmware that configures |
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it to act as a hardware monitor. |
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Prefix: 'nsa320' |
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Addresses scanned: none |
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Datasheet: Not available, driver was reverse engineered based upon the |
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Zyxel kernel source |
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Author: |
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Adam Baker <[email protected]> |
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Description |
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----------- |
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This chip is known to be used in the Zyxel NSA320 and NSA325 NAS Units and |
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also in some variants of the NSA310 but the driver has only been tested |
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on the NSA320. In all of these devices it is connected to the same 3 GPIO |
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lines which are used to provide chip select, clock and data lines. The |
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interface behaves similarly to SPI but at much lower speeds than are normally |
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used for SPI. |
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Following each chip select pulse the chip will generate a single 32 bit word |
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that contains 0x55 as a marker to indicate that data is being read correctly, |
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followed by an 8 bit fan speed in 100s of RPM and a 16 bit temperature in |
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tenths of a degree. |
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sysfs-Interface |
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--------------- |
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============= ================= |
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temp1_input temperature input |
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fan1_input fan speed |
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============= ================= |
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Notes |
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----- |
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The access timings used in the driver are the same as used in the Zyxel |
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provided kernel. Testing has shown that if the delay between chip select and |
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the first clock pulse is reduced from 100 ms to just under 10ms then the chip |
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will not produce any output. If the duration of either phase of the clock |
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is reduced from 100 us to less than 15 us then data pulses are likely to be |
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read twice corrupting the output. The above analysis is based upon a sample |
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of one unit but suggests that the Zyxel provided delay values include a |
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reasonable tolerance. |
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The driver incorporates a limit that it will not check for updated values |
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faster than once a second. This is because the hardware takes a relatively long |
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time to read the data from the device and when it does it reads both temp and |
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fan speed. As the most likely case for two accesses in quick succession is |
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to read both of these values avoiding a second read delay is desirable.
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