Hi ! Sorry again for the long delay to answer :( On Sun, Jun 20, 2004 at 04:51:31PM +0400, Evgeniy Polyakov wrote: > Hello. > I have some notes about such devices and design of the Linux kernel w1 > implementation. > > 1. After rereading specs for various *<->w1 master > devices I found that all they do support bit interface since it is > required by w1 search algorithm. Yes, the DS2490 can access the bus using bit mode. > Maybe some devices exist that drive > some register when they found new slave device on the bus and provide > it's address in other register, and also such devices require flags that > indicates that search must be proceeded or stopped. > I don't now about such devices, but if they exist one can easily > update w1 master operations structure to support search callback for > it, and main master's ->process() routing to call it instead of default > bit-banging w1_search() call. I will do it if you provide datasheet. The DS2490 has a function that can be call that does the whole search process automatically. It returns the list of devices found. > 2. By design I leave main master's ->process() call as easy as possible > and move all data processing out to slave device drivers(family > drivers). Master just searches for devices on the bus, requests it's > drivers and provide them all needed functionality. > Now I extended a bit w1 master operations to support read_/write_byte() > and reset_bus() calls, so if provided they will be called before bit > operations. Good > So in case of DS2490 you just need to write driver implementing read_bit > and write_bit operations using some USB commands, then register it as > master. Any slave devices that will be found in bus connected to DS2490 > will use automatically any operations that you will provide, but they > actually needs only bit operations. Others are just extensions. Ok, using read_bit with the DS2490 is a little like using soft OpenGL with a graphic card that supports all the functions in hard. However, I don't have any time to look at that by now. You already a very good job by writing such drivers, and I suggest to include these patches as they are now, it will be possible to improve them later, it is already a very good start. -- .''`. Aurelien Jarno GPG: 1024D/F1BCDB73 : :' : Debian GNU/Linux developer | Electrical Engineering Student `. `' aurel32 at debian.org | aurelien at aurel32.net `- people.debian.org/~aurel32 | www.aurel32.net
