linux-kernel - Re: [PATCH v2 1/2] firmware: qcom: scm: Add SCM storage interface support

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Message-ID: <2d28b5d0-c5f4-4085-b2d0-18128b021416@oss.qualcomm.com>
Date: Wed, 28 Jan 2026 14:39:32 +0100
From: Konrad Dybcio <konrad.dybcio@....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 1/2] firmware: qcom: scm: Add SCM storage interface
 support

On 1/26/26 12:44 PM, Junhao Xie wrote:
> Add infrastructure to support accessing TrustZone-protected storage
> devices through SCM (Secure Channel Manager) calls. Some Qualcomm
> platforms protect their firmware storage (typically SPI NOR flash)
> via TrustZone, making it inaccessible from the non-secure world.
> 
> Signed-off-by: Junhao Xie <bigfoot@...xa.com>
> Tested-by: Xilin Wu <sophon@...xa.com>
> ---

[...]

> +int qcom_scm_storage_send_cmd(enum qcom_scm_storage_type storage_type,
> +			      enum qcom_scm_storage_cmd_id cmd_id,
> +			      u64 lba, void *data, size_t size)

Please add kerneldoc, as this is an exported function

> +{
> +	struct qcom_scm_storage_payload *payload __free(qcom_tzmem) = NULL;
> +	struct qcom_scm_res scm_res = {};
> +	struct qcom_scm_desc desc = {};
> +	phys_addr_t payload_addr;
> +	size_t buf_size;
> +	int ret;
> +
> +	buf_size = sizeof(*payload);
> +	if (data)
> +		buf_size += size;
> +
> +	payload = qcom_tzmem_alloc(__scm->mempool, buf_size, GFP_KERNEL);
> +	if (!payload)
> +		return -ENOMEM;
> +
> +	memset(payload, 0, buf_size);

You're overwriting the data part a line below, let's just zero out the
cmd+details (sizeof(*payload)) part

> +	if (data)

(please add a \n above - normally

foo = xyz;
if (abc)
	...

implies the condition takes into account the previous line)

[...]

> +	if (!__qcom_scm_is_call_available(__scm->dev, QCOM_SCM_SVC_STORAGE,
> +					 QCOM_SCM_STORAGE_CMD))
> +		return;
> +
> +	ret = qcom_scm_storage_send_cmd(QCOM_SCM_STORAGE_SPINOR,
> +					QCOM_SCM_STORAGE_GET_INFO,
> +					0, &info, sizeof(info));

I'm curious what happens if the call is available but SPINOR is not
populated onboard..

I thiiiink it should return STORAGE_RESULT_INVALID_PARAMETER but I'm not
a 100% sure. Guess we'll see down the road.


> +	if (ret < 0) {
> +		dev_warn(scm->dev, "scm storage get info failed: %d\n", ret);
> +		return;
> +	}
> +
> +	total_blocks = le64_to_cpu(info.total_blocks);
> +	block_size = le32_to_cpu(info.block_size);
> +
> +	dev_dbg(scm->dev, "scm storage size %llu bytes\n",
> +		total_blocks * block_size);
> +
> +	storage_dev = platform_device_alloc("qcom_scm_storage", -1);

-1 is PLATFORM_DEVID_NONE

Let's use PLATFORM_DEVID_AUTO to allow potentially multiple instances of
this driver being spawned down the road

Konrad