linux-kernel - Re: [PATCH v2 0/2] mtd: devices: Qualcomm SCM storage support

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Message-ID: <dd89949a-11da-4c57-9b1a-2fba181988cc@oss.qualcomm.com>
Date: Wed, 28 Jan 2026 13:43:05 -0800
From: Trilok Soni <trilokkumar.soni@....qualcomm.com>
To: Junhao Xie <bigfoot@...xa.com>, Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mtd@...ts.infradead.org, Xilin Wu <sophon@...xa.com>
Subject: Re: [PATCH v2 0/2] mtd: devices: Qualcomm SCM storage support

On 1/26/2026 3:44 AM, Junhao Xie wrote:
> This patch series adds support for accessing storage devices managed by
> Qualcomm TrustZone firmware via SCM (Secure Channel Manager) by
> introducing a new MTD driver.
> 
> On some Qualcomm platforms, firmware or BIOS-related storage (typically
> SPI NOR flash) is not directly accessible from the non-secure world.
> All read, write, and erase operations must be performed through SCM
> interfaces provided by the secure firmware. As a result, existing MTD
> SPI NOR drivers cannot be used directly on these systems.
> 
> This series introduces a new MTD device driver that exposes such
> firmware-managed storage as a standard MTD device in the Linux kernel.
> The driver is built on top of the existing Qualcomm SCM infrastructure
> and integrates with the MTD subsystem to provide a uniform interface to
> userspace.
> 
> This driver has been tested on Radxa Dragon Q6A, based on the Qualcomm
> QCS6490 SoC, with a Winbond W25Q256JWPIQ SPI NOR flash device.
> 
> Note that this platform previously used the standard Qualcomm Linux
> firmware, which allowed direct access to the QSPI controller without
> needing this driver. However, we plan to migrate to a Windows-compatible
> firmware which is more feature-complete but restricts direct access.
> Device tree changes for this transition will be sent separately.
> 
> If kernel boots with EL2, access to the SCM storage will be denied. This
> needs more investigation.

So you plan to enable this driver only w/ the Gunyah based configuration
and disable for the KVM one through the devicetree overlay ? I just
don't want to break the KVM boot flow on other platforms supporting
qcs6490. 

> 
> Changes in v2:
> - Convert enum qcom_scm_storage_result to macro definitions
> - Use __qcom_scm_is_call_available() instead of a machine allowlist
> - Add missing __packed annotations and endianness handling
> - Introduce struct qcom_scm_storage_payload to improve readability
> - Always compiled-in qcom_scm_storage_send_cmd() and qcom_scm_storage_init()
> https://lore.kernel.org/lkml/F138514E18CB55B6+20251218180205.930961-1-bigfoot@radxa.com/
> 
> Tested-by: Xilin Wu <sophon@...xa.com>
> Signed-off-by: Junhao Xie <bigfoot@...xa.com>
> ---
> Junhao Xie (2):
>       firmware: qcom: scm: Add SCM storage interface support
>       mtd: devices: Add Qualcomm SCM storage driver
> 
>  drivers/firmware/qcom/qcom_scm.c       | 161 ++++++++++++++++++++
>  drivers/firmware/qcom/qcom_scm.h       |   3 +
>  drivers/mtd/devices/Kconfig            |  17 +++
>  drivers/mtd/devices/Makefile           |   1 +
>  drivers/mtd/devices/qcom_scm_storage.c | 265 +++++++++++++++++++++++++++++++++
>  include/linux/firmware/qcom/qcom_scm.h |  34 +++++
>  6 files changed, 481 insertions(+)
> ---
> base-commit: 63804fed149a6750ffd28610c5c1c98cce6bd377
> change-id: 20260126-scm-storage-v2-0a4f3e900b88
> 
> Best regards,