Messages in this thread | | | From | Joshua Clayton <> | Subject | Re: [PATCH v2 0/8] rtc: enable adjustment of clock offset | Date | Tue, 26 Jan 2016 06:56:40 -0800 |
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Ping?
On Monday, January 04, 2016 10:31:18 AM Joshua Clayton wrote: > Alexandre, > this is the second version of apatch set to be able to adjust the > clock on a pcf2123, but with a big addition. I am also proposing > a couple of new rtc api functions and a new sysfs file. > > Patches 1-5 are very much v2 patches that address All of the > concerns you had with v1. It is my hope to get them merged without > too much more trouble. > The rtc _needs_ patches 1-5 in order to use the clock offset adjustment at all (current upstream code resets it to zero during device probe, so it doesn't survive a reboot) Should I split out patches 1-5 to make them easier to review?
> Patches 6-8 are attemping to add a new function to the rtc class > to adjust the clock rate. I hope I am going about this the right way, > But here goes. > I am hoping to have some discussion about 6, 7 and 8. Particularly whether parts per billion is the right unit (I think it is) and whether "offset" is the best name for the attribute (not as sure).
> A number of rtc devices, such as the NXP pcf2123 include a facility > to adjust the clock in order to compensate for temperature or a > crystal, capacitor, etc, that results in the rtc clock not running > at exactly 32.768 kHz. > > This patchset adds kernel and sysfs hooks to access that ability. > > One datasheet suggests it might be adjusted based on input from > a temperature sensor. I could also potentially see it being set > as part of ntp calibration. > > Data sheets I have seen refer to this as a clock offset, and measure it > in parts per million (ppm), however they often reference ppm to 2 digits > of precision, which makes integer ppm less than ideal. I use parts per > billion, which more than covers the precision needed and works nicely > within 32 bits > > The name "offset" came from the pcf-2123 datasheet and is used by at > least some other data sheets. I would be happy to use a different term > if someone else comes up with something more concise. > > Changes since v1: > - Use the BIT() macro for all register bits > - Remove unneeded range checks from read/write functions > - Merge patch 3 (replace magic numbers with defines) into patch 2 > - Add a proper commit message to patch 5, now patch 4 > - Fix a function alignment bug. > - Move OSC_HAS_STOPPED check into pcf2123_rtc_read_time, and get rid of > pcf2123_time_valid() > - Drop patches refactoring pcf2123 sysfs. > - Add rtc interface and rtc sysfs file for clock offset > > Joshua Clayton (8): > rtc-pcf2123: define registers and bit macros > rtc-pcf2123: clean up reads from the chip > rtc-pcf2123: clean up writes to the rtc chip > rtc-pcf2123: refactor chip reset into a function > rtc-pcf2123: avoid resetting the clock if possible > rtc: Add functions to set and read clock offset > rtc: implement a sysfs interface for clock offset > rtc-pcf2123: implement read_offset and set_offset > > drivers/rtc/interface.c | 57 ++++++++++ > drivers/rtc/rtc-pcf2123.c | 271 +++++++++++++++++++++++++++++++++------------- > drivers/rtc/rtc-sysfs.c | 29 +++++ > include/linux/rtc.h | 4 + > 4 files changed, 284 insertions(+), 77 deletions(-) > > Thanks again, Joshua Clayton
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