2016-03-11 16:56 GMT+01:00 Franck Jullien <franck.jullien@xxxxxxxxxxxxxxxxxxx>:
> This patch serie allow modules to register their own devicetree.
>
> I started to work on this because I work on a PCIe board with
> a FPGA. The FPGA acts as a bridge. Behind this bridge I use Xilinx
> IPs. The problem is that Xilinx IPs support in the Kernel as been
> made with Zynq or Microblaze in mind. They require devicetree
> support.
>
> The idea is that a pci module could be shipped with its own
> devicetree describing whats behind the BARs.
>
> Here is an example of what could be such a tree:
> /dts-v1/;
> / {
> compatible = "pci,pci_dev";
> #address-cells = <1>;
> #size-cells = <1>;
>
> bar@0 {
> compatible = "pci,pci_bar";
> #address-cells = <1>;
> #size-cells = <1>;
> reg = <0 0>;
> /* Dynamically set by module */
> ranges = <0 0 0>;
>
> axi_vdma_0: axivdma@10000 {
> compatible = "xlnx,axi-vdma-1.00.a";
> #dma-cells = <1>;
> reg = <0x10000 0x10000>;
> xlnx,num-fstores = <0x8>;
> xlnx,flush-fsync = <0x1>;
> dma-channel@0x10000 {
> compatible = "xlnx,axi-vdma-s2mm-channel";
> /* New flag */
> irq_direct_mapping;
> /* Dynamically set by module */
> interrupts = <0>;
> xlnx,datawidth = <0x40>;
> } ;
> };
> };
> };
>
> Ranges an interrupts are dynamically set by the module at
> probe time.
>
> For interrupts, we could also think of a special interrupt
> controller for this application. For now [7/8] looks like
> a hack.
>
> An example of module using this serie (and the associated dts) can
> be found on my Github account [1].
>
> I my example you'll see that I use a Makefile rule to compile
> the devicetree and then generates a C array from the blob.
> The module should use the dtb target to generate the blob but
> I couldn't find the good way to do that for a module on a x86
> target. Help is welcome.
>
> Patch [1/8] should no be part of this serie. However, it shows
> that if we allow independant devicetree, every architecture should
> be able to select USE_OF. The better would be to have of support
> as a module.
>
> Don't take this serie as a finished work. There is a lot of aspects
> to improve. May be we should start to implement multi-root node
> properly as a lot of functions assume of_root is the only devicetree
> present in the system.
>
> Franck Jullien (8):
> arch/x86: Add Kconfig USE_OF
> drivers/of: attach top level tree nodes to sysfs with their name
> drivers/of: export of_attach_node_sysfs
> drivers/of: export of_update_property
> drivers/of: rename __of_find_all_nodes and export it
> of.h: add for_each_compatible_node_from helper
> drivers/of: allow irq direct mapping
> drivers/of: parse_phandle_with_args to look in node's root
>
> arch/x86/Kconfig | 7 ++++++
> drivers/of/base.c | 49 +++++++++++++++++++++++++++++++++++++++++-----
> drivers/of/dynamic.c | 4 +-
> drivers/of/irq.c | 6 +++++
> drivers/of/of_private.h | 1 -
> drivers/of/platform.c | 6 ++++-
> drivers/of/unittest.c | 4 +-
> include/linux/of.h | 15 ++++++++++++-
> 8 files changed, 78 insertions(+), 14 deletions(-)
>
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Here is the missing link:
[1] https://github.com/fjullien/of_pci_module_example
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