On Sun, Mar 5, 2017 at 8:28 AM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > On 03/01/2017 07:29 PM, Rick Altherr wrote: >> >> Resending in plain text. >> >> On Tue, Feb 28, 2017 at 7:45 PM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: >>> >>> On 02/28/2017 04:49 PM, Joel Stanley wrote: >>>> >>>> >>>> On Wed, Mar 1, 2017 at 6:44 AM, Rick Altherr <raltherr@xxxxxxxxxx> >>>> wrote: >>>>> >>>>> >>>>> Aspeed AST2400/AST2500 BMC SoCs include a 16 channel, 10-bit ADC. This >>>>> driver implements reading the ADC values, enabling channels via device >>>>> tree, and optionally providing channel labels via device tree. Low and >>>>> high threshold interrupts are supported by the hardware but not >>>>> implemented. >>>>> >>>>> Signed-off-by: Rick Altherr <raltherr@xxxxxxxxxx> >>>> >>>> >>>> >>>> Looks good. Some minor comments below. >>>> >>>> Is there a reason you wrote a hwmon driver instead of an iio driver? I >>>> wasn't sure what the recommended subsystem is. >>> >>> >>> >>> Excellent point. Question is really if there is a plan to add support for >>> thresholds. If not, an iio driver might be more appropriate. >>> >>> Guenter >>> >> >> The hardware supports firing interrupts on high and low thresholds. >> I'm not planning to use that feature yet so I didn't implement it. >> Would you prefer that I leave it as is (maybe with a TODO), implement >> the thresholding, or change to iio? >> > > Let's try to determine the intended use of the ADC. I don't find the > datasheet > online; all I can find is brief summaries which don't me tell much, but > suggest > that it is a general purpose ADC and not specifically intended for hardware > monitoring. What is the minimum sampling rate ? That should give us an idea. > If it is in the uS range, iio would be more appropriate (and the iio-hwmon > bridge could be used if a channel is in fact used for hardware monitoring). > > Thanks, > Guenter > AST2500 is a BMC SoC from Aspeed (https://www.aspeedtech.com/products.php?fPath=20&rId=440). The BMC is a separate, always-on computer that manages the health and remote management for a server. The driver I sent is for the ADCs included in the SoC that are intended to monitor power rails on the server motherboard but are really just general-purpose ADCs. According to the (not public) datasheet, the sampling rate is 10-500kHz, resolution is 10-bit, and precision +/- 2%. This is my first time writing a linux driver for ADCs. My cursory look at iio indicates that that will work fine for this driver and the hwmon-iio bridge will suffice for the userspace stack which is currently expecting hwmon APIs. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
