[Qemu-devel] [RFC PATCH V1 00/14] Dynamic machine model creation from device trees

[Peter A. G. Crosthwaite]

Hello

This is a general RFC for a framework developed at Petalogix for creating QEMU 
models based on a passed device tree. Machine models are dynamically 
constructed from parsing a Device Tree Specification (DTS) - no more hard-coded 
machine models, which is critical for the FPGA-based platforms (i.e. 
target-microblaze) but also will be very useful for forthcoming DTS-driven ARM 
kernels as well. Device models (including QDev models) are tagged as being 
associated with a "compatible" string. If a node with the registered compatible 
string is found when the argument dts is parsed, then the QDev model is 
instantiated.

For example, An ethernet controller might have a device tree node:

    Ethernet_MAC: address@hidden {
                        compatible = "xlnx,xps-ethernetlite-4.00.a", 
"xlnx,xps-ethernetlite-1.00.a";
                        device_type = "network";
                        interrupt-parent = <&xps_intc_0>;
                        interrupts = < 1 0 >;
                                local-mac-address = [ 00 0a 35 00 22 01 ];
                        reg = < 0x81000000 0x10000 >;
                        ...
                } ;

Our framework registers the compatibility  "xlnx,xps-ethernetlite-1.00.a" as 
being associated with the xilinx.ethlite qdev model (hw/xilinx_ethlite.c), and 
each time this compatiblity is discovered in the device tree, the qdev model is 
instantiated (see path 10/14 for code details on this particular example).The 
reg property is used to set the device base address and the interrupt 
properties are used to connect interrupts. Device tree (more info @ 
devicetree.org) provides a standarised way of specifiying such connecitons, and 
we use all this to create machine models.

Compatibilities are registered statically from within device models as such:

    fdt_qdev_register_compatibility(&xilinx_ethlite_fdt_qdev_ops,
        "xlnx,xps-ethernetlite-1.00.a");
        
Where the first argument is a struct containing constant and handlers provided 
by the deivce model to handle device instantiation. Device instantiation is 
performed by the framework (not the Qdev models themselves)

We have also set up a mechanism for machine models to communicate with each 
other by means other than bus transactions. DTS provides a means to specify 
arbitrary interconnections between devices, and we use this to instantiate 
connections such as hierarchical interrupt controllers and point to point DMA 
interconnections. This provides a consistent and clean way of specifying 
inter-device connectivity other than via the system bus.

The platform is tested for Xilinx Microblaze and PPC platforms, and we have 
been using it both interally at PetaLogix and publishing to customers for 
approx. 6 months now. We have setup FDT instantiation code for all of the 
xilinx microbalze/PPC supported periphperals. We are currently developing 
support for an ARM platform. The framework itself is however independent of 
architecture so this could be used for creating machine models for any machine. 

This patch series is a minimal patch series containing support for only 
microblaze and a handful of peripherals. Support for a more complete range of 
device models and other cpu architectures will come in future patches.

We would welcome any comments or questions about the approach so that we can 
get it merged upstream.

Regards,
Peter

Edgar E. Iglesias (2):
  microblaze: Make the MSR PVR bit non writable
  microblaze: Add an MSR_PVR constant and use it.

Peter A. G. Crosthwaite (12):
  qemu-coroutine: Add simple work queue support
  device_tree: Extended interface for fdt_generic
  fdt_generic: First revision
  xilinx_uartlite: Added fdt gen. platform support
  pflash_cfi01: Added fdt generic platform support
  qdev: Added fn for querying device property types
  fdt_generic_qdev: first revision
  xilinx_timer: Added fdt_generic platform support
  xilinx_intc: Added fdt generic platform support
  xilinx_ethlite: Added fdt generic platform support
  vl.c: Added hw_dtb/kern_dtb command line opts
  microblaze_generic_fdt: first revision

 Makefile.objs                 |    4 +
 Makefile.target               |    1 +
 device_tree.c                 |  202 +++++++++++++++++++
 device_tree.h                 |   30 +++
 hw/fdt_generic.c              |  199 +++++++++++++++++++
 hw/fdt_generic.h              |   92 +++++++++
 hw/fdt_generic_devices.h      |    8 +
 hw/fdt_generic_qdev.c         |   75 +++++++
 hw/fdt_generic_qdev.h         |   46 +++++
 hw/fdt_generic_util.c         |  196 ++++++++++++++++++
 hw/fdt_generic_util.h         |   43 ++++
 hw/microblaze_generic_fdt.c   |  439 +++++++++++++++++++++++++++++++++++++++++
 hw/pflash_cfi01.c             |   37 ++++
 hw/qdev-properties.c          |    9 +
 hw/qdev.h                     |    1 +
 hw/xilinx_ethlite.c           |   39 ++++-
 hw/xilinx_intc.c              |   35 ++++-
 hw/xilinx_timer.c             |   39 ++++-
 hw/xilinx_uartlite.c          |   24 +++
 qemu-coroutine-lock.c         |   13 ++
 qemu-coroutine.h              |    9 +
 qemu-options.hx               |   47 +++++
 sysemu.h                      |    4 +
 target-microblaze/cpu.h       |    1 +
 target-microblaze/translate.c |   11 +-
 vl.c                          |   19 ++
 26 files changed, 1617 insertions(+), 6 deletions(-)
 create mode 100644 hw/fdt_generic.c
 create mode 100644 hw/fdt_generic.h
 create mode 100644 hw/fdt_generic_devices.h
 create mode 100644 hw/fdt_generic_qdev.c
 create mode 100644 hw/fdt_generic_qdev.h
 create mode 100644 hw/fdt_generic_util.c
 create mode 100644 hw/fdt_generic_util.h
 create mode 100644 hw/microblaze_generic_fdt.c

-- 
1.7.3.2