[RFC PATCH v3 0/7] xen/arm: scmi: introduce SCI SCMI SMC multi-agent support

[Grygorii Strashko <gragst.linux@xxxxxxxxx>]

Hi,

This is respin of RFCv2 series from Oleksii Moisieiev [1] which was send pretty 
long time ago (2022),
with the main intention is to resume this discussion in public and gather more 
opinions.

Hence the code was previously sent long time ago there are pretty high number 
of changes,
including rebase on newer Xen version 4.20.0-rc2, which already contains some 
basic SCMI SMC driver
introduced by Andrei Cherechesu, commit 3e322bef8bc0 ("xen/arm: firmware: Add 
SCMI over SMC calls
handling layer").

Patch 1 "xen/arm: add generic SCI subsystem"
- rebased and refactored
- introduced DEVICE_ARM_SCI DT device class and used for SCI drivers probing 
instead of custom,
  linker sections based implementation.
- added SCI API for Dom0 DT handling, instead of manipulating with ARM arch 
dom0 code directly.
- TODO: RFC changes in XEN_DOMCTL_assign_device OP processing

Patch 2 "xen/arm: scmi-smc: update to be used under sci subsystem"
- update driver introduced by commit 3e322bef8bc0 ("xen/arm: firmware: Add SCMI 
over SMC calls
handling layer") be used under sci subsystem.
- no functional changes in general

Patch 3 "xen/arm: scmi-smc: passthrough SCMI SMC to guest domain
This is new change which allows passthrough SCMI SMC, single agent interface to 
guest domain
cover use case "thin Dom0 with guest domain, which serves as Driver domain".
See patch commit message for full description.

Patch 4 - xen/arm: scmi: introduce SCI SCMI SMC multi-agent driver
- added "xen,scmi-secondary-agents" property in "chosen" to inform SCI SCMI 
multi-agent driver
  about available agents and their configuration. It defines <agent_id> to 
<smc-id,scmi_shm> map.
  This option is Xen specific as Xen is the only one entry in the system which 
need to know
  about SCMI multi-agent support and configuration.
- each guest using SCMI should be configured with SCMI agent_id, so SCMI
  FW can implement Agent-specific permission policy.
  -- dom0: dom0_scmi_agent_id=<agent_id> in Xen command line option
  -- toolstack: arm_sci = "type=scmi_smc_multiagent,agent_id=<agent_id>"
  -- dom0less: todo: "xen,sci_type", "xen,sci_agent_id" properties in 
"xen,domain" nodes.
- factored out SCMI generic definitions (re-usable)
- factored out SCMI shmem code (re-usable)
- the SCMI passthrough configuration for guest domains is similar to any other 
HW passthrough cfg.

Patches 5-7
- no major changes, except to follow rebase and changes in previous patches

Regarding patches 5-7 I'd like to rise a question and I, personally, feel very 
skeptical doing any
kind of SCMI DT nodes generation as from toolstack as from Xen.
1) SCMI is no differ as any other HW MFD device, and HW passthrough 
configuration works for it in
   the same way.
2) if toolstack generates DT then dom0less case might need it also, but this 
means more code in Xen,
   so, with certification in mind, it means more overhead requirements, docs 
and testing.
   In my opinion if something can be done outside "kernel" - it should.
   So better invest in tools (imagebuilder, lopper, etc.) instead.
3) Hence SCMI DT bindings are pretty complex the corresponding guest DT nodes 
can't be generated
   from scratch - the user still need to add scmi node, protocols and protocols 
subnodes in the
   partial device tree, at least empty. But stop, not exactly empty - the 
properties like
   "#clock-cells" need to be added to avoid DTC warnings. Such behavior is 
rather confusing than
   helpful.
4) Exposing the Host Device tree in Dom0 is another questionable thing for 
toolstack SCMI DT
   generation. It consumes 128K of memory on Renesas r8a779g0-whitehawk.
5) No needs for additional public API (XEN_DOMCTL_get_sci_info, 
GUEST_SCI_SHMEM_BASE..) if dropped 

Code can be found at:
https://github.com/GrygiriiS/xen/commits/master_v4h_sci_v13_dt_gen

[1] RFC v2:
https://patchwork.kernel.org/project/xen-devel/cover/cover.1644341635.git.oleksii_moisieiev@xxxxxxxx/

SCMI spec:
https://developer.arm.com/documentation/den0056/e/?lang=en

SCMI bindings:
https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/access-controllers/access-controllers.yaml

Reference EL3 FW:
RPI5: https://github.com/xen-troops/arm-trusted-firmware/commits/rpi5_dev/
Renesas v4h: 
https://github.com/GrygiriiS/arm-trusted-firmware/commits/rcar_gen4_v2.7_v4x-scmi_upd/

base-commit: c3f5d1bb40b5 ("automation/cirrus-ci: introduce FreeBSD randconfig 
builds")

Grygorii Strashko (2):
  xen/arm: scmi-smc: update to be used under sci subsystem
  xen/arm: scmi-smc: passthrough SCMI SMC to domain, single agent

Oleksii Moisieiev (5):
  xen/arm: add generic SCI subsystem
  xen/arm: scmi: introduce SCI SCMI SMC multi-agent driver
  libs: libxenhypfs - handle blob properties
  xen/arm: Export host device-tree to hypfs
  xen/arm: scmi: generate scmi dt node for DomUs

 MAINTAINERS                                  |   6 +
 docs/man/xl.cfg.5.pod.in                     |  51 ++
 docs/misc/xen-command-line.pandoc            |  18 +
 tools/include/libxl.h                        |   5 +
 tools/include/xenctrl.h                      |   3 +
 tools/libs/ctrl/xc_domain.c                  |  18 +
 tools/libs/hypfs/core.c                      |   2 -
 tools/libs/light/libxl_arm.c                 | 311 ++++++-
 tools/libs/light/libxl_create.c              |  12 +
 tools/libs/light/libxl_internal.h            |   3 +
 tools/libs/light/libxl_types.idl             |  12 +
 tools/xl/xl_parse.c                          |  83 ++
 xen/arch/arm/Kconfig                         |  16 +
 xen/arch/arm/Makefile                        |   1 +
 xen/arch/arm/device.c                        |   5 +
 xen/arch/arm/dom0less-build.c                |  13 +
 xen/arch/arm/domain.c                        |  12 +-
 xen/arch/arm/domain_build.c                  |  11 +-
 xen/arch/arm/domctl.c                        |  22 +
 xen/arch/arm/firmware/Kconfig                |  36 +-
 xen/arch/arm/firmware/Makefile               |   2 +
 xen/arch/arm/firmware/sci.c                  | 187 ++++
 xen/arch/arm/firmware/scmi-proto.h           | 164 ++++
 xen/arch/arm/firmware/scmi-shmem.c           | 172 ++++
 xen/arch/arm/firmware/scmi-shmem.h           |  45 +
 xen/arch/arm/firmware/scmi-smc-multiagent.c  | 858 +++++++++++++++++++
 xen/arch/arm/firmware/scmi-smc.c             | 161 +++-
 xen/arch/arm/host_dtb_export.c               |  28 +
 xen/arch/arm/include/asm/domain.h            |  11 +
 xen/arch/arm/include/asm/firmware/sci.h      | 214 +++++
 xen/arch/arm/include/asm/firmware/scmi-smc.h |  41 -
 xen/arch/arm/vsmc.c                          |   4 +-
 xen/common/domctl.c                          |  13 +
 xen/drivers/passthrough/device_tree.c        |   7 +
 xen/include/asm-generic/device.h             |   1 +
 xen/include/public/arch-arm.h                |  12 +
 xen/include/public/device_tree_defs.h        |   1 +
 xen/include/public/domctl.h                  |  11 +
 38 files changed, 2471 insertions(+), 101 deletions(-)
 create mode 100644 xen/arch/arm/firmware/sci.c
 create mode 100644 xen/arch/arm/firmware/scmi-proto.h
 create mode 100644 xen/arch/arm/firmware/scmi-shmem.c
 create mode 100644 xen/arch/arm/firmware/scmi-shmem.h
 create mode 100644 xen/arch/arm/firmware/scmi-smc-multiagent.c
 create mode 100644 xen/arch/arm/host_dtb_export.c
 create mode 100644 xen/arch/arm/include/asm/firmware/sci.h
 delete mode 100644 xen/arch/arm/include/asm/firmware/scmi-smc.h

-- 
2.34.1