linux-kernel - [PATCH 0/2] mailbox: add support for clients to request channels by arguments

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Message-Id: <20241219-mbox_request_channel_by_args-v1-0-617a6910f842@linaro.org>
Date: Thu, 19 Dec 2024 13:07:45 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Jassi Brar <jassisinghbrar@...il.com>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-samsung-soc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 andre.draszik@...aro.org, peter.griffin@...aro.org, kernel-team@...roid.com, 
 willmcvicker@...gle.com, daniel.lezcano@...aro.org, 
 vincent.guittot@...aro.org, ulf.hansson@...aro.org, arnd@...db.de, 
 Tudor Ambarus <tudor.ambarus@...aro.org>
Subject: [PATCH 0/2] mailbox: add support for clients to request channels
 by arguments

There are clients that can discover channel identifiers at runtime by
parsing a shared memory for example, as in the ACPM interface's case.
For such cases passing the channel identifiers via DT is redundant.

Supply a new framework API: mbox_request_channel_by_args().

It works by supplying the usual client pointer as the first argument and
a pointer to a ``const struct mbox_xlate_args`` as a second. The newly
introduced struct is modeled after ``struct of_phandle_args``. The API
will search the client's node for a ``mbox`` phandle, identify the
controller's device node, and then call that controller's xlate() method
that will return a pointer to a mbox_chan or a ERR_PTR. The binding
between the channel and the client is done in the typical way.

This allows clients to reference the controller node as following:
        firmware {
                acpm_ipc: power-management {
                        compatible = "google,gs101-acpm-ipc";
-                       mboxes = <&ap2apm_mailbox 0 0
-                                 &ap2apm_mailbox 0 1
-                                 &ap2apm_mailbox 0 2
-                                 &ap2apm_mailbox 0 3
-                                 &ap2apm_mailbox 0 4
-                                 &ap2apm_mailbox 0 5
-                                 &ap2apm_mailbox 0 6
-                                 &ap2apm_mailbox 0 7
-                                 &ap2apm_mailbox 0 8
-                                 &ap2apm_mailbox 0 9
-                                 &ap2apm_mailbox 0 10
-                                 &ap2apm_mailbox 0 11
-                                 &ap2apm_mailbox 0 12
-                                 &ap2apm_mailbox 0 13
-                                 &ap2apm_mailbox 0 14>;
+                       mbox = <&ap2apm_mailbox>;
                        shmem = <&apm_sram>;
                };
        };

Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
---
Tudor Ambarus (2):
      dt-bindings: mailbox: add support for referencing controllers solely by node
      mailbox: add support for clients to request channels by arguments

 .../devicetree/bindings/mailbox/mailbox.txt        | 19 ++++++--
 drivers/mailbox/mailbox.c                          | 57 ++++++++++++++++++++++
 include/linux/mailbox.h                            | 17 +++++++
 include/linux/mailbox_client.h                     |  3 ++
 include/linux/mailbox_controller.h                 |  4 ++
 5 files changed, 96 insertions(+), 4 deletions(-)
---
base-commit: 78d4f34e2115b517bcbfe7ec0d018bbbb6f9b0b8
change-id: 20241219-mbox_request_channel_by_args-7115089ed492

Best regards,
-- 
Tudor Ambarus <tudor.ambarus@...aro.org>