On Wed, Aug 01, 2012 at 04:12:23PM -0400, John Rippetoe wrote:
> On 08/01/2012 12:52 PM, Guenter Roeck wrote:
> >On Wed, Aug 01, 2012 at 11:59:40AM -0400, John Rippetoe wrote:
> >>I am attempting to setup lm-sensors on an embedded platform, more
> >>specifically the Micromint Electrum 100. I'm experiencing an issue
> >>with the output of the sensors program where the output is obviously
> >>bogus, especially given that all the values are identical. Some
> >>basic details about the system:
> >>
> >>- 6.04 Debian squeeze
> >>- Atmel AT91SAM9G20 cpu (armv5)
> >>- ADC128S052 SPI ADC
> >>- atmel_spi driver built in to pre-compiled kernel
> >>- hwmon, and adcxx loaded as modules later
> >>
> >>The adcxx kernel module successfully loads and binds to the device.
> >>Reading the sysfs files it creates for each input, the same value of
> >>52799 is seen on each. I know the device works because I have
> >>tested it with some userland example code provided by the
> >>manufacturer and get expected values for various inputs.
> >>
> >>I initially had an issue with getting the adcxx module to bind with
> >>the device, but found that the problem was because of an alias
> >>problem. In ./arch/arm/mach-at91/board-electrum-100.c the ADC was
> >>declared with an alias as shown in the code segment below:
> >>
> >>/static struct spi_board_info ek_spi_devices[] = {
> >>/ .....
> >>/ { /* ADC128S052 analog inputs */
> >>/ .modalias = "adc128s052",
> >>/ .chip_select = 2,
> >>/ .max_speed_hz = 8 * 1000 * 1000,
> >>/ .bus_num = 1,
> >>/ },
> >>/ .....
> >>
> >./arch/arm/mach-at91/board-electrum-100.c is not in mainline, so this is a bit
> >difficult. Given the above, it may even be that there is a separate driver for
> >the chip somewhere in your tree (ok, I think I found the patch, there isn't,
> >but that means this never worked).
> I could have sworn that I saw it in mainline, but now that I check I
> see it is not there. Sorry about that! I am not sure what you mean
> as far as the driver never working and exactly what patch you are
> talking about. Could you clarify?
http://stoian.us/misc/files/linux-3.3.0-micromint.patch
Since the patch sets modalias to "adc128s052", and a driver with that name does
not exist in the kernel, it can not have worked, at least not with this
configuration.
> >Other than that, there could be many things wrong. Chip select, bus number,
> >clock speed, chip access mode. There is no example for a working instantiation
> >in the upstream kernel, so I have no idea what the valid parameters might be.
> >You mentioned user mode access worked - maybe you can compare it with the kernel
> >settings.
> As far as I can tell (and I may be wrong here, this is all still
> pretty new to me) the bus and chip select are all correct. Clock
> speed could be an issue I suppose. I just did the reverse math on
> the value that the driver is reporting and realized that before it
> is converted, the raw value is 2 bytes worth of 1's. I am going to
> trace through the spi_write_then_read() function in the adcxx driver
> and compare its method to that used by the user mode program and the
> atmel_spi driver. I'm not sure how far I am going to get though.
>
Doesn't sound good, and I am not entirely sure if using spi_write_then_read() is
correct for this chip. You might try the access in single-channel mode to see if
it makes a difference.
Guenter
> John
> >Guenter
> >
> >>Rather than change the alias in board-electrum-100.c and have to
> >>recompile and install a new kernel, I opted to add the alias as
> >>shown above to adcxx_ids[] in adcxx.c
> >>
> >>/static const struct spi_device_id adcxx_ids[] = {
> >>/ { "adcxx1s", 1 },
> >>/ { "adcxx2s", 2 },
> >>/ { "adcxx4s", 4 },
> >>/ { "adcxx8s", 8 },
> >>/ { "adc128s052", 8}, <-- added here
> >>/ { },
> >>/};
> >>
> >>With that done, sensors starting giving me output, just not anything
> >>worth reading. At this point I'm a little baffled as to what is
> >>causing this and crawling the internet has turned up nothing. Here
> >>is my output for sensors:
> >>
> >>electrum100:~# sensors
> >>adcxx8s-spi-1-2
> >>Adapter: SPI adapter
> >>in0: +52.80 V
> >>in1: +52.80 V
> >>in2: +52.80 V
> >>in3: +52.80 V
> >>in4: +52.80 V
> >>in5: +52.80 V
> >>in6: +52.80 V
> >>in7: +52.80 V
> >>
> >>
> >>Any help would be greatly appreciated. Thank you.
> >>
> >> - John
> >>
> >>_______________________________________________
> >>lm-sensors mailing list
> >>lm-sensors@xxxxxxxxxxxxxx
> >>http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
> >>
>
>
> --
> Respectfully,
>
> John Rippetoe
> Communication Concepts
> 813-888-6611
>
>
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