linux.git/include/linux/mailbox_controller.h, branch v7.1-rc2

mailbox: update kdoc for struct mbox_controller

2026-04-18T18:07:36+00:00

Add field for missing lock around the hrtimer. Add 'Required' where
the core checks for valid entries.

Signed-off-by: Wolfram Sang 
Reviewed-by: Geert Uytterhoeven 
Signed-off-by: Jassi Brar

mailbox: prefix new constants with MBOX_

2026-04-13T01:04:17+00:00

Commit 89e5d7d61600 ("mailbox: remove superfluous internal header")
moved some constants to a public header but forgot to add a mailbox
specific prefix. Add this now to prevent future collisions on a too
generic naming.

Link: https://sashiko.dev/#/patchset/20260327151112.5202-2-wsa%2Brenesas%40sang-engineering.com
Signed-off-by: Wolfram Sang 
Reviewed-by: Sudeep Holla 
Signed-off-by: Jassi Brar

mailbox: Fix NULL message support in mbox_send_message()

2026-03-29T16:12:01+00:00

The active_req field serves double duty as both the "is a TX in
flight" flag (NULL means idle) and the storage for the in-flight
message pointer. When a client sends NULL via mbox_send_message(),
active_req is set to NULL, which the framework misinterprets as
"no active request". This breaks the TX state machine by:

 - tx_tick() short-circuits on (!mssg), skipping the tx_done
   callback and the tx_complete completion
 - txdone_hrtimer() skips the channel entirely since active_req
   is NULL, so poll-based TX-done detection never fires.

Fix this by introducing a MBOX_NO_MSG sentinel value that means
"no active request," freeing NULL to be valid message data. The
sentinel is defined in the subsystem-internal mailbox.h so that
controller drivers within drivers/mailbox/ can reference it, but
it is not exposed to clients outside the subsystem.

Fifteen in-tree callers send NULL (doorbell-style IPCs on Qualcomm,
Tegra, TI, Xilinx, i.MX, SCMI, and PCC platforms). All were
audited for regression:

 - Most already work around the bug via knows_txdone=true with a
   manual mbox_client_txdone() call, making the framework's
   tracking irrelevant. These are unaffected.

 - Poll-based callers (Xilinx zynqmp/r5) are strictly better off:
   the poll timer now correctly detects NULL-active channels
   instead of silently skipping them.

 - irq-qcom-mpm.c was a pre-existing bug -- the only Qualcomm
   caller that omitted the knows_txdone + mbox_client_txdone()
   pattern. Fixed in a companion commit ("irqchip/qcom-mpm: Fix
   missing mailbox TX done acknowledgment").

 - No caller sets both a tx_done callback and sends NULL, nor
   combines tx_block=true with NULL sends, so the newly reachable
   callback/completion paths are never exercised.

Also update tegra-hsp's flush callback, which directly inspects
active_req to wait for the channel to drain: the old "!= NULL"
check becomes "!= MBOX_NO_MSG", otherwise flush spins until
timeout since the sentinel is non-NULL.

The only tradeoff is that 'MBOX_NO_MSG' can not be used as a message
by clients.

Reported-by: Joonwon Kang 
Reviewed-by: Douglas Anderson 
Signed-off-by: Jassi Brar

mailbox: remove superfluous internal header

2026-03-29T16:07:26+00:00

Quite some controller drivers use the defines from the internal header
already. This prevents controller drivers outside the mailbox directory.
Move the defines to the public controller header to allow this again as
the defines are not strictly internal anyhow.

Signed-off-by: Wolfram Sang 
Reviewed-by: Sudeep Holla 
Reviewed-by: Daniel Baluta 
Signed-off-by: Jassi Brar

mailbox: Allow controller specific mapping using fwnode

2025-09-25T01:32:00+00:00

Introduce optional fw_node() callback which allows a mailbox controller
driver to provide controller specific mapping using fwnode.

The Linux OF framework already implements fwnode operations for the
Linux DD framework so the fw_xlate() callback works fine with device
tree as well.

Acked-by: Jassi Brar 
Reviewed-by: Andy Shevchenko 
Signed-off-by: Anup Patel 
Link: https://lore.kernel.org/r/20250818040920.272664-6-apatel@ventanamicro.com
Signed-off-by: Paul Walmsley

mailbox: Remove devm_mbox_controller_unregister

2025-05-26T21:23:39+00:00

Commit e898d9cdd3a9("mailbox: Add device-managed registration functions")
introduced device-managed API for mailbox, but in the past 7 years,
there is no user for devm_mbox_controller_unregister. So remove it.

Signed-off-by: Peng Fan 
Signed-off-by: Jassi Brar

mailbox: sort headers alphabetically

2025-03-27T01:58:25+00:00

Sorting headers alphabetically helps locating duplicates,
and makes it easier to figure out where to insert new headers.

Signed-off-by: Tudor Ambarus 
Signed-off-by: Jassi Brar

mailbox: forward the hrtimer if not queued and under a lock

2022-05-23T19:45:24+00:00

This reverts commit c7dacf5b0f32957b24ef29df1207dc2cd8307743,
"mailbox: avoid timer start from callback"

The previous commit was reverted since it lead to a race that
caused the hrtimer to not be started at all. The check for
hrtimer_active() in msg_submit() will return true if the
callback function txdone_hrtimer() is currently running. This
function could return HRTIMER_NORESTART and then the timer
will not be restarted, and also msg_submit() will not start
the timer. This will lead to a message actually being submitted
but no timer will start to check for its compleation.

The original fix that added checking hrtimer_active() was added to
avoid a warning with hrtimer_forward. Looking in the kernel
another solution to avoid this warning is to check hrtimer_is_queued()
before calling hrtimer_forward_now() instead. This however requires a
lock so the timer is not started by msg_submit() inbetween this check
and the hrtimer_forward() call.

Fixes: c7dacf5b0f32 ("mailbox: avoid timer start from callback")
Signed-off-by: Björn Ardö 
Signed-off-by: Jassi Brar

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55+00:00

Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Enrico Weigelt 
Reviewed-by: Kate Stewart 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman

mailbox: Support blocking transfers in atomic context

2018-12-22T04:31:26+00:00

The mailbox framework supports blocking transfers via completions for
clients that can sleep. In order to support blocking transfers in cases
where the transmission is not permitted to sleep, add a new ->flush()
callback that controller drivers can implement to busy loop until the
transmission has been completed. A new mbox_flush() function can be
called by mailbox consumers in atomic context to make sure a transfer
has completed.

Signed-off-by: Thierry Reding 
Signed-off-by: Jassi Brar