On Sun, Dec 08, 2013 at 03:00:36PM +0100, Éric Piel wrote: > On 08-12-13 14:46, Sebastian Reichel wrote: > : > >No, it's connected via I2C. Please note, that the N900's accelerometer > >is already supported, but only when initialized via legacy boardcode. > > > >The problem is, that I can't specify negative values in the device > >tree file (the device tree compiler complains). I couldn't find any > >example of negative numbers in any dts file, so I guess, that > >negative numbers are not supported. > > > : > >I just want to port the existing boardcode to device tree. > >The existing platform data is defined as rx51_lis3lv02d_data in > >arch/arm/mach-omap2/board-rx51-peripherals.c. > Oh! Yes, then the values themselves should be fine. > Indeed, the problem is in the parsing of the DT values. > Currently, lis3lv02d_init_dt() reads values as unsigned int: > > u32 val; > if (of_get_property(np, "st,axis-x", &val)) > pdata->axis_x = val; > > So it's quite unlikely to get negative ;-) Is there a way to read > signed ints in DT? If so, I can update the driver. I just found a link, which describes how to put negative values into the DTS, so that the device tree compiler understands them and translates them into 2's-compliment [0]. The kernel code currently does not provide of_property_read_s32(), but it seems that there was just no use case so far. At least one of the DT binding maintainers seems to be finde with introducing it [1]. I will prepare a patch, which adds of_property_read_s32 and another one, which updates lis3lv02d to use the new function. [0] http://www.mail-archive.com/linux-arm-msm@xxxxxxxxxxxxxxx/msg05121.html [1] http://www.mail-archive.com/linux-arm-msm@xxxxxxxxxxxxxxx/msg05125.html -- Sebastian
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