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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