So far our parsing of {iommu,msi}-map properties has always blindly
assumed that the output specifiers will always have exactly 1 cell.
This typically does happen to be the case, but is not actually enforced
(and the PCI msi-map binding even explicitly states support for 0 or 1
cells) - as a result we've now ended up with dodgy DTs out in the field
which depend on this behaviour to map a 1-cell specifier for a 2-cell
provider, despite that being bogus per the bindings themselves.
Since there is some potential use[1] in being able to map at least
single input IDs to multi-cell output specifiers (and properly support
0-cell outputs as well), add support for properly parsing and using the
target nodes' #cells values, albeit with the unfortunate complication of
still having to work around expectations of the old behaviour too.
-- Robin.
Unlike single #{}-cell, it is complex to establish a linear relation
between input 'id' and output specifier for multi-cell properties, thus
it is always expected that len never going to be > 1.
These changes have been tested on QEMU for the arm64 architecture.
Since, this would also need update in dt-schema, raised PR[2] for the
same.
[1] https://lore.kernel.org/all/20250627-video_cb-v3-0-51e18c0ffbce@quicinc.com/
[2] PR for iommu-map dtschema: https://github.com/devicetree-org/dt-schema/pull/184
Robin,
Could this series be pulled into an immutable branch/tag, if it doesn't make
it into the v7.1 merge window? There are client changes dependent on it,
So it would help to get them moving forward rather than waiting another
cycle.
Thanks,
Vijay
V12:
- Call of_node_put() unconditionally in imx_pcie_add_lut_by_rid()
thereby addressing comments from Bjorn Helgaas.
Link to v11:
https://lore.kernel.org/r/20260325-parse_iommu_cells-v11-0-1fefa5c0e82c@oss.qualcomm.com
V11:
- Added explicit filter_np parameter to of_map_id() and of_map_msi_id()
per Dmitry Baryshkov's review feedback, making the filter explicit
instead of overloading arg->np as both input filter and output parameter.
- Removed of_node_put() from inside of_map_id(), making the caller responsible
for reference management. Updated of_msi_xlate() to properly handle reference counting.
- Collected ACKed by tags, and fixed minor typos.
Link to v10:
https://lore.kernel.org/r/20260309-parse_iommu_cells-v10-0-c62fcaa5a1d8@oss.qualcomm.com
V10:
- Move of_map_iommu_id()/of_map_msi_id() from include/linux/of.h to
drivers/of/base.c as out-of-line helpers per feedback from Marc Zyngier
and Rob Herring.
- Add kernel-doc to document both helpers for discoverability and
usage clarity.
- Fix of_map_msi_id() wrapper and all its callers (cdx_msi.c,
irq-gic-its-msi-parent.c, drivers/of/irq.c) to correctly use the new
struct of_phandle_args-based API with proper of_node_put() handling
as per feeback from Dmitry.
Link to v9:
https://lore.kernel.org/r/20260301-parse_iommu_cells-v9-0-4d1bceecc5e1@oss.qualcomm.com
V9:
- Updated TO/CC list based on feedback to include all relevant
maintainers.
- No functional changes to the patches themselves.
Link to V8:
https://lore.kernel.org/all/20260226074245.3098486-1-vijayanand.jitta@oss.qualcomm.com/
V8:
- Removed mentions of of_map_args from commit message to match code.
Link to V7:
https://lore.kernel.org/all/20260210101157.2145113-1-vijayanand.jitta@oss.qualcomm.com/
V7:
- Removed of_map_id_args structure and replaced it with
of_phandle_args as suggested by Dmitry.
Link to V6:
https://lore.kernel.org/all/20260121055400.937856-1-vijayanand.jitta@oss.qualcomm.com/
V6:
- Fixed build error reported by kernel test bot.
Link to V5:
https://lore.kernel.org/all/20260118181125.1436036-1-vijayanand.jitta@oss.qualcomm.com/
V5:
- Fixed Build Warnings.
- Raised PR for iommu-map dtschema: https://github.com/devicetree-org/dt-schema/pull/184
Link to V4:
https://lore.kernel.org/all/20251231114257.2382820-1-vijayanand.jitta@oss.qualcomm.com/
V4:
- Added Reviewed-by tag.
- Resolved warnings reported by kernel test bot, minor code
reorganization.
Link to V3:
https://lore.kernel.org/all/20251221213602.2413124-1-vijayanand.jitta@oss.qualcomm.com/
V3:
- Added Reviewed-by tag.
- Updated of_map_id_args struct as a wrapper to of_phandle_args and
added comment description as suggested by Rob Herring.
Link to V2:
https://lore.kernel.org/all/20251204095530.8627-1-vijayanand.jitta@oss.qualcomm.com/
V2:
- Incorporated the patches from Robin that does the clean implementation.
- Dropped the patches the were adding multi-map support from this series
as suggested.
V1:
https://lore.kernel.org/all/cover.1762235099.git.charan.kalla@oss.qualcomm.com/
RFC:
https://lore.kernel.org/all/20250928171718.436440-1-charan.kalla@oss.qualcomm.com/#r
Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
---
Charan Teja Kalla (1):
of: Factor arguments passed to of_map_id() into a struct
Robin Murphy (2):
of: Add convenience wrappers for of_map_id()
of: Respect #{iommu,msi}-cells in maps
drivers/cdx/cdx_msi.c | 8 +-
drivers/iommu/of_iommu.c | 6 +-
drivers/irqchip/irq-gic-its-msi-parent.c | 11 +-
drivers/of/base.c | 213 ++++++++++++++++++++++++-------
drivers/of/irq.c | 11 +-
drivers/pci/controller/dwc/pci-imx6.c | 34 +++--
drivers/pci/controller/pcie-apple.c | 6 +-
drivers/xen/grant-dma-ops.c | 5 +-
include/linux/of.h | 30 ++++-
9 files changed, 240 insertions(+), 84 deletions(-)
---
base-commit: 3fa5e5702a82d259897bd7e209469bc06368bf31
change-id: 20260301-parse_iommu_cells-1c33768aebba
Best regards,
--
Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>