On Thu, Aug 13, 2009 at 3:52 PM, srinivasramana<srinivas.ramana@xxxxxxxxx> wrote: > > Hi All, > > I have been working on the feasibility of having multiple device > nodes(serial type device) for a single device so that applications can treat > each of these device nodes as separate devices. > > 1. Can i write a tty driver which creates multiple nodes(i will set minors > to the number of nodes i need) > 2. Now, If I write from user space on any of these nodes i have seen that it > comes to the tty drivers write call. > 3. I want to know how do i link my physical driver with this tty driver? > 4. If mutiple applications are waiting on read on different nodes, how do i > wake up a particular read based on the incoming data from hardware(on Rx > interrupt)? > > please help. > > Thanks & Regards, > -- Srinivas R > > > > srinivasramana wrote: >> >> Hi, >> >> Thanks for the response. I have explored the option of FIFOs, but the >> issue is I need Full duplex support from the devices. In that case I will >> have to use two FIFOs for each device. So, it would be good to know if >> there is any better option. >> >> Also, I was thinking of multiple virtual device nodes with single UART. >> But, I want to know how do I have these layers communicate? multiple >> virtual ttys with single UART work? >> Please suggest. >> >> Thanks & Regards, >> -- Srinivas R >> >> >> matthias-44 wrote: >>> >>> Hi, >>> >>> Why you don't put everything in user space. So you just need the >>> driver to communicate with your UART port. >>> Use pipes for communication between your applications and the >>> UART-controller-application in user space. >>> >>> regards, >>> Matthias >>> >>> 2009/7/19 srinivas ramana <srinivas.ramana@xxxxxxxxx>: >>>> Hi All, >>>> >>>> I have a UART port on my device. A micro controller which drives >>>> multiple >>>> other devices is connected to this UART port. >>>> I need all those devices, connected to micro controller, to be visible >>>> to >>>> Linux applications as separate UART devices/ports. >>>> >>>> What is the best way to do this? What all driver layers i need to >>>> add/modify. Please help. >>>> Thanks in advance. >>>> >>>> Note: assume there is a protocol between micro controller & Linux to >>>> understand which device is requesting service. >>>> >>>> Thanks & Regards, >>>> -- Srinivas R I'm going to ignore the electrical aspect of multidrop rs-232, but I really don't think that works at all. Assuming you have somehow overcome that major hurdle, I don't understand your problem. You start with a standard multi-port uart serial driver. Then modify it such that when data comes in your driver decodes the protocol to get the address/routing info and delivers the data payload to appropriate device (/dev/ttyx) as if it were a multi-port device. On write, your driver gets data from userspace (/dev/ttyx) and wraps the comm protocol around it and sends it on its way. >From a software perspective none of this unusual, strange, or weird in any way. If you think about a 8-port serial card, it works exactly as you describe. A single hardware driver gets the incoming data from the card, decodes the cards signaling protocol and delivers the data to the correct device (/dev/ttyx). And on write, it uses the cards signalling protocol to tell it which port to send the data out. The only difference is a hardware card uses hardware registers to control the routing, where as you have it embedded in the data stream. Note: TCP/IP also embeds the routing info in the data stream (ie. the port). It is a totally standard thing to do. Greg -- Greg Freemyer Head of EDD Tape Extraction and Processing team Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer Preservation and Forensic processing of Exchange Repositories White Paper - <http://www.norcrossgroup.com/forms/whitepapers/tng_whitepaper_fpe.html> The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
