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

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Message-ID: <2397C90D8A633438+88e8956b-5753-4842-a1c7-b0f6a78580c1@radxa.com>
Date: Thu, 29 Jan 2026 20:47:23 +0800
From: Junhao Xie <bigfoot@...xa.com>
To: Trilok Soni <trilokkumar.soni@....qualcomm.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 2026/1/29 5:43, Trilok Soni wrote:

> 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.

On systems booted with EL2/KVM, the SCM storage GET_INFO call currently
returns -EINVAL. If a platform does not support SPI-NOR or SCM storage,
__qcom_scm_is_call_available() will cause the initialization to bail out 
early.

There is no DT-based enable/disable mechanism, and this should not affect
KVM boot flow on other platforms.

Other QCS6490 LE platforms do not support SCM storage, as the LE firmware
does not support SPI-NOR boot. Radxa Dragon Q6A uses WP firmware and boots
from SPI-NOR.

The root cause of SCM storage being unavailable under EL2/KVM is still under
investigation.

[    0.770124] qcom_scm: convention: smc arm 64
[    0.775005] qcom_scm firmware:scm: qseecom: found qseecom with 
version 0x1402000
[    0.782990] qcom_scm firmware:scm: scm storage get info failed: -22
[    0.999095] qcom_qseecom qcom_qseecom: setting up client for 
qcom.tz.uefisecapp

Thanks for your reply.
Best regards,
Junhao Xie