linux-kernel - [PATCH v2 2/4] firmware: qcom: uefisecapp: add support for R/O UEFI vars

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Message-Id: <20250621-more-qseecom-v2-2-6e8f635640c5@oss.qualcomm.com>
Date: Sat, 21 Jun 2025 22:56:11 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Bjorn Andersson <andersson@...nel.org>,
        Maximilian Luz <luzmaximilian@...il.com>,
        Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: [PATCH v2 2/4] firmware: qcom: uefisecapp: add support for R/O
 UEFI vars

For some platforms (e.g. Lenovo Yoga C630) we don't yet know a way to
update variables in the permanent storage. However being able to read
the vars is still useful as it allows us to get e.g. RTC offset.

Add a quirk for QSEECOM specifying that UEFI variables for this platform
should be registered in read-only mode.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
---
 drivers/firmware/qcom/qcom_qseecom_uefisecapp.c | 18 +++++++++++++++++-
 include/linux/firmware/qcom/qcom_qseecom.h      |  2 ++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/qcom/qcom_qseecom_uefisecapp.c b/drivers/firmware/qcom/qcom_qseecom_uefisecapp.c
index 98a463e9774bf04f2deb0f7fa1318bd0d2edfa49..05f700dcb8cf3189f640237ff0e045564abb8264 100644
--- a/drivers/firmware/qcom/qcom_qseecom_uefisecapp.c
+++ b/drivers/firmware/qcom/qcom_qseecom_uefisecapp.c
@@ -792,6 +792,12 @@ static efi_status_t qcuefi_query_variable_info(u32 attr, u64 *storage_space, u64
 	return status;
 }
 
+static const struct efivar_operations qcom_efivars_ro_ops = {
+	.get_variable = qcuefi_get_variable,
+	.get_next_variable = qcuefi_get_next_variable,
+	.query_variable_info = qcuefi_query_variable_info,
+};
+
 static const struct efivar_operations qcom_efivar_ops = {
 	.get_variable = qcuefi_get_variable,
 	.set_variable = qcuefi_set_variable,
@@ -804,7 +810,9 @@ static const struct efivar_operations qcom_efivar_ops = {
 static int qcom_uefisecapp_probe(struct auxiliary_device *aux_dev,
 				 const struct auxiliary_device_id *aux_dev_id)
 {
+	unsigned long *quirks = aux_dev->dev.platform_data;
 	struct qcom_tzmem_pool_config pool_config;
+	const struct efivar_operations *ops;
 	struct qcuefi_client *qcuefi;
 	int status;
 
@@ -829,7 +837,15 @@ static int qcom_uefisecapp_probe(struct auxiliary_device *aux_dev,
 	if (status)
 		return status;
 
-	status = efivars_register(&qcuefi->efivars, &qcom_efivar_ops);
+	if (quirks &&
+	    *quirks & QCOM_QSEECOM_QUIRK_RO_UEFIVARS) {
+		dev_dbg(&aux_dev->dev, "R/O UEFI vars implementation\n");
+		ops = &qcom_efivars_ro_ops;
+	} else {
+		ops = &qcom_efivar_ops;
+	}
+
+	status = efivars_register(&qcuefi->efivars, ops);
 	if (status)
 		qcuefi_set_reference(NULL);
 
diff --git a/include/linux/firmware/qcom/qcom_qseecom.h b/include/linux/firmware/qcom/qcom_qseecom.h
index 3387897bf36843cccd0bd933dd562390bf674b14..8d6d660e854fdb0fabbef10ab5ee6ff23ad79826 100644
--- a/include/linux/firmware/qcom/qcom_qseecom.h
+++ b/include/linux/firmware/qcom/qcom_qseecom.h
@@ -51,4 +51,6 @@ static inline int qcom_qseecom_app_send(struct qseecom_client *client,
 	return qcom_scm_qseecom_app_send(client->app_id, req, req_size, rsp, rsp_size);
 }
 
+#define QCOM_QSEECOM_QUIRK_RO_UEFIVARS		BIT(0)
+
 #endif /* __QCOM_QSEECOM_H */

-- 
2.39.5