From 630300d5fcb6ee9c32c75d8b576c100fbb794159 Mon Sep 17 00:00:00 2001 From: Adam Baker Date: Sat, 5 Mar 2016 15:34:56 +0000 Subject: hwmon: Create an NSA320 hardware monitoring driver Create a driver to support the hardware monitoring chip present in the Zyxel NSA320 and some of the other Zyxel NAS devices. The driver reads fan speed and temperature from a suitably pre-programmed MCU on the device. Signed-off-by: Adam Baker [groeck: Dropped .owner field initialization] Signed-off-by: Guenter Roeck --- Documentation/hwmon/nsa320 | 53 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 Documentation/hwmon/nsa320 (limited to 'Documentation/hwmon') diff --git a/Documentation/hwmon/nsa320 b/Documentation/hwmon/nsa320 new file mode 100644 index 000000000000..fdbd6947799b --- /dev/null +++ b/Documentation/hwmon/nsa320 @@ -0,0 +1,53 @@ +Kernel driver nsa320_hwmon +========================== + +Supported chips: + * Holtek HT46R065 microcontroller with onboard firmware that configures + it to act as a hardware monitor. + Prefix: 'nsa320' + Addresses scanned: none + Datasheet: Not available, driver was reverse engineered based upon the + Zyxel kernel source + +Author: + Adam Baker + +Description +----------- + +This chip is known to be used in the Zyxel NSA320 and NSA325 NAS Units and +also in some variants of the NSA310 but the driver has only been tested +on the NSA320. In all of these devices it is connected to the same 3 GPIO +lines which are used to provide chip select, clock and data lines. The +interface behaves similarly to SPI but at much lower speeds than are normally +used for SPI. + +Following each chip select pulse the chip will generate a single 32 bit word +that contains 0x55 as a marker to indicate that data is being read correctly, +followed by an 8 bit fan speed in 100s of RPM and a 16 bit temperature in +tenths of a degree. + + +sysfs-Interface +--------------- + +temp1_input - temperature input +fan1_input - fan speed + +Notes +----- + +The access timings used in the driver are the same as used in the Zyxel +provided kernel. Testing has shown that if the delay between chip select and +the first clock pulse is reduced from 100 ms to just under 10ms then the chip +will not produce any output. If the duration of either phase of the clock +is reduced from 100 us to less than 15 us then data pulses are likely to be +read twice corrupting the output. The above analysis is based upon a sample +of one unit but suggests that the Zyxel provided delay values include a +reasonable tolerance. + +The driver incorporates a limit that it will not check for updated values +faster than once a second. This is because the hardware takes a relatively long +time to read the data from the device and when it does it reads both temp and +fan speed. As the most likely case for two accesses in quick succession is +to read both of these values avoiding a second read delay is desirable. -- cgit v1.2.3