On Thu, Aug 22, 2013 at 02:43:38PM -0700, David Hawkins wrote: > Hi S.Saravanan, > > > I have a custom board with four MPC8640 nodes connected over > > a transparent PCI express switch . In this configuration one node is > > configured as host(Root Complex) and others as agents(End Point). Thus > > the legacy PCI software works fine . However the mainline kernel lacks > > any standard support for Inter-processor communication over PCI. I am > > in the process of developing an Ethernet over PCI driver for the same > > on the lines of rionet . However I am facing the following problems. > > > > a) I can generate MSI interrupts from End Point to Root Complex over > > PCI . But the vice-versa is not possible . However i need a method to > > interrupt the End Point from the Root Complex to complete my driver. > > Root complex's would normally interrupt a device via a PCIe write > to a register in a BAR on the end-point (or in extended configuration > space registers depending on the hardware implementation). > > > Only previous references I can find are this post > > http://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg25765.html > > However this uses doorbells and I think may not be possible in MPC8640. > > PCIe drivers need some way to interrupt the processor, so there must > be an option somewhere ... for example, what are the message register > interrupts intended for? See p479 > > http://cache.freescale.com/files/32bit/doc/ref_manual/MPC8641DRM.pdf > > (Ira and myself have not used the MPC8640 so are not familiar with > its user manual). > > > Any pointers on this issue and guidance on this driver development would > > be helpful . > > We use the Ethernet-over-PCI driver that Ira developed. Our next boards > will use an MPC8308, but we don't currently have any in a PCIe device > form-factor (just the MPC8038RDB), so he has not ported it to PCIe. > > Feel free to discuss your ideas for your PCIe driver (eg., why start > with rionet rather than Ira's driver), either on-list, or email Ira > and myself directly. >
One further note. You might want to look at rproc/rpmsg and their virtio driver support. That seems to be where the Linux world is moving for inter-processor communications. See for example the ARM CPUs interfacing with DSPs. Ira _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
