[U-Boot-Users] soft_i2c and ds1307 with tqm823l

Seb James seb at peak.uklinux.net
Mon Jun 30 16:08:00 CEST 2003

Wolfgang Denk wrote:
[ snip ]

>>Ok, well I've successfully compiled with CONFIG_HARD_I2C and have 
>>communicated with my clock, so that is good. Next up is transferring the 
>>date in u-boot to linux, but I'm sure that will be documented somewhere.
>You don't "transfer" the daye. Linux will pick it  up  itself  (which
>requires an RTC driver and eventually some modifications).

Let me check that I understand: As far as I can see the u-boot realtime 
clock drivers just allow you to set and read the time from the u-boot 
command line; a useful utility. If linux is to read the time from the 
realtime clock it must have a realtime clock driver of its own; there's 
no way that u-boot can pass the time to linux at boot time? (Of course, 
this would be fraught with difficulties, because depending on how fast 
your cpu boots linux, a different amount of time would elapse before 
linux could actually do something with the passed date stamp).

So, next up for me is to write a linux driver for the ds1307. I was 
actually in the middle of that before getting sidetracked by the u-boot 
rtc code. However, the u-boot code has enabled me to hardware debug my 
realtime clock circuit, so that was very useful.  Has anyone written a 
linux driver for the ds1307 or similar? (I'm cross posting to the 
linuxppc-embedded list to ask this question).

>>As for CONFIG_SOFT_I2C; Attached (really this time) is a diff between 
>>the original u-boot-0.4.0/include/configs/TQM823L.h and the one that I 
>>have altered. The compile of soft_i2c.c fails with the following error 
>That's because you did  not  define  the  required  macros  (see  for
>example the configuration in lwmon.h).
Right, so it's not the case that you just #define CONFIG_SOFT_I2C; you 
have to correctly define the macros. I shall do some work on the readme 
and post a diff later on. Thanks for the pointers.



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