Message-ID: <20250228045356.3527662-1-quic_srichara@quicinc.com>
Date: Fri, 28 Feb 2025 10:23:54 +0530
From: Sricharan R <quic_srichara@...cinc.com>
To: <jassisinghbrar@...il.com>, <robh@...nel.org>, <krzk+dt@...nel.org>,
        <conor+dt@...nel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <andersson@...nel.org>, <konradybcio@...nel.org>,
        <manivannan.sadhasivam@...aro.org>, <dmitry.baryshkov@...aro.org>,
        <quic_srichara@...cinc.com>
Subject: [PATCH V3  0/2] mailbox: tmel-qmp: Introduce QCOM TMEL QMP mailbox driver

From: Sricharan Ramabadhran <quic_srichara@...cinc.com>

The QMP mailbox is the primary means of communication between TME-L SS
and other subsystem on the SoC. A dedicated pair of inbound and outbound
mailboxes is implemented for each subsystem/external execution environment
which needs to communicate with TMEL for security services. The inbound
mailboxes are used to send IPC requests to TME-L, which are then processed
by TME-L firmware and accordingly the responses are sent to the requestor
via outbound mailboxes.

It is an IPC transport protocol which is light weight and supports
a subset of API's. It handles link initialization, negotiation,
establishment and communication across client(APPSS/BTSS/AUDIOSS)
and server(TME-L SS).

   -----------------------------------------------       ---------------------------------------------------
  |                                              |       |                                                 |
  |                 SOC  CLIENT                  | SOC   |                TME-L  SS                        |
  |                                              | AHB   |                                                 |
  |     ----------    ---------   ---------      |       | ------    -------     --------    ------------  |
  |     |        |    |       |   |       |      | WO    | |     | R |     |     |      |    |SERVICES   | |
  |     | APPS   |<-->| TMEL  |<->|       |------------->| | IN  |-->|     |     | TMEL |    |--------   | |
  |     |        |    | COM   |   | QMP   |      | RO    | |     | W | QMP |<--->| COM  |<-->| a) ATTEST | |
  |     |        |    |       |   |       |<-------------| | OUT |<--|     |     |      |    | b) CRYPTO | |
  |     |        |    |       |   |       |      |       | |     |   |     |     |      |    | .. more   | |
  |     ---------     ---------   ---------      |       | ------    -------     -------     ------------  |
  |                                              |       |                                                 |
   -----------------------------------------------       --------------------------------------------------

TME-L SS provides different kinds of services like secureboot, remote image authentication,
key management, crypto, OEM provisioning etc. This patch adds support for remote image
authentication. Support for rest of the services can be added.

Remote proc driver subscribes to this mailbox and uses the mbox_send_message to use
TME-L to securely authenticate/teardown the images.

Since clients like same rproc driver use SCM/TMEL across socs, the goal here was to abstract the
TMEL-QMP SS functionality, so that clients should be able to connect and send messages with
a common API.

[v3]
     Patch #1
     -------
        Fixed wrappings.
        Made mailbox-cells as a required property and changed value to '1'.
        Fixed to use compatible as filename.
        Renamed compatible as per Krzystof's comments.
        Dropped unused label.


     Patch #2
     --------
	Fixed wrong code/comments wrappings.
        Fixed Kconfig and Makefile entries to right place.
	Removed unused headers inclusion.
        Fixed locking, removed the mutexes and having only tx spinlock.
        Removed the use of global ptr for tmel, made it as device specific.
        Replaced pr_err/pr_debug with dev_err/dev_dbg in all places.
        Fixed usage of dev_err_probe.
        Fixed xlate callback as per comments.
        Used devm equivalents and kcalloc version as per comments.
        Removed all un-nessecary wrapper macros for register access, inlined it
        as per comments.
        Re-organised the function layout as per comments and make it more readable.
        Removed the pictures in headers files as per comments.
        Used Field_prep/get as per comments.
        Fixed all other comments as well.

    Testing:
    --------
    Following tests were done and no issues.

       *)  Checkpatch
       *)  Codespell
       *)  Sparse
       *)  kerneldoc check
       *)  Kernel lock debugging
       *)  dt_binding_check and dtbs_check

[v2]
     Added HW description in the bindings patch.
     Fixed review comments for bindings from Krzysztof and Dmitry
     Changed patch#2 driver to add work for mailbox tx processing
     Cleaned up patch#2 for some checkpatch warnings.
     There are some checkpatch [CHECK] like below, which looks like false positive.

	CHECK: Macro argument 'm' may be better as '(m)' to avoid precedence issues
	#1072: FILE: include/linux/mailbox/tmelcom-qmp.h:40:
	+#define TMEL_MSG_UID_CREATE(m, a)      ((u32)(((m & 0xff) << 8) | (a & 0xff)))

[v1] RFC Post

Sricharan Ramabadhran (2):
  dt-bindings: mailbox: Document qcom,tmel-qmp
  mailbox: tmelite-qmp: Introduce TMEL QMP mailbox driver

 .../bindings/mailbox/qcom,ipq5424-tmel.yaml   |  62 ++
 drivers/mailbox/Kconfig                       |  10 +
 drivers/mailbox/Makefile                      |   2 +
 drivers/mailbox/qcom-tmel-qmp.c               | 836 ++++++++++++++++++
 include/linux/mailbox/tmelcom-qmp.h           | 122 +++
 5 files changed, 1032 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mailbox/qcom,ipq5424-tmel.yaml
 create mode 100644 drivers/mailbox/qcom-tmel-qmp.c
 create mode 100644 include/linux/mailbox/tmelcom-qmp.h

-- 
2.34.1

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