[PATCH 0/3] soc: renesas: add MFIS driver

Wolfram Sang
2026-03-17T13:06:50Z

Renesas R-Car MFIS offers multiple features but most importantly
mailboxes and hwspinlocks. Because they share a common register space
and a common register unprotection mechanism, a single driver was chosen
to handle all dependencies. (MFD and auxiliary bus have been tried as
well, but they failed because of circular dependencies.)

In this first step, the driver implements common register access and a
mailbox controller. hwspinlock support will be added incrementally, once
the subsystem allows out-of-directory drivers (patches already under
review). This driver has been tested on a Renesas Ironhide board (R-Car
X5H) and is able to communicate with the SCP via mailboxes. Also, the
mailbox-test driver was used to confirm back-and-forth communication
between two application cores.

Because of its multifunctional nature, the driver lives in
drivers/soc/renesas. As large parts of these patches handle mailbox
support, review from mailbox expeirenced people is much appreciated.

A branch can be found here:

git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git renesas/x5h/mfis-single-driver

Thanks and happy hacking,

Wolfram

Changes since last internal RFC:
* no functional change
* extended parts of the binding description
* reworded parts of commit messages
* dual licence the dt-binding header
* dropped unneeded Kconfig dependency on HWSPINLOCK
* rebased to linux-next as of 20260316

Wolfram Sang (3):
dt-bindings: soc: renesas: add MFIS binding documentation
soc: renesas: Add Renesas R-Car MFIS driver
soc: renesas: add X5H PRR support

.../soc/renesas/renesas,r8a78000-mfis.yaml | 160 +++++++++
drivers/soc/renesas/Kconfig | 9 +
drivers/soc/renesas/Makefile | 1 +
drivers/soc/renesas/rcar-mfis.c | 325 ++++++++++++++++++
drivers/soc/renesas/renesas-soc.c | 8 +-
.../mailbox/renesas,r8a78000-mfis.h | 27 ++
6 files changed, 529 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/soc/renesas/renesas,r8a78000-mfis.yaml
create mode 100644 drivers/soc/renesas/rcar-mfis.c
create mode 100644 include/dt-bindings/mailbox/renesas,r8a78000-mfis.h

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