firmware: qcom: move Qualcomm code into its own directory

We're getting more and more qcom specific .c files in drivers/firmware/
and about to get even more. Create a separate directory for Qualcomm
firmware drivers and move existing sources in there.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Elliot Berman <quic_eberman@quicinc.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com> # sc8280xp-lenovo-thinkpad-x13s
Link: https://lore.kernel.org/r/20231017092732.19983-2-brgl@bgdev.pl
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

drivers/firmware/qcom/qcom_qseecom_uefisecapp.c

@@ -0,0 +1,871 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Client driver for Qualcomm UEFI Secure Application (qcom.tz.uefisecapp).
+ * Provides access to UEFI variables on platforms where they are secured by the
+ * aforementioned Secure Execution Environment (SEE) application.
+ *
+ * Copyright (C) 2023 Maximilian Luz <luzmaximilian@gmail.com>
+ */
+
+#include <linux/efi.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/ucs2_string.h>
+
+#include <linux/firmware/qcom/qcom_qseecom.h>
+
+/* -- Qualcomm "uefisecapp" interface definitions. -------------------------- */
+
+/* Maximum length of name string with null-terminator */
+#define QSEE_MAX_NAME_LEN			1024
+
+#define QSEE_CMD_UEFI(x)			(0x8000 | (x))
+#define QSEE_CMD_UEFI_GET_VARIABLE		QSEE_CMD_UEFI(0)
+#define QSEE_CMD_UEFI_SET_VARIABLE		QSEE_CMD_UEFI(1)
+#define QSEE_CMD_UEFI_GET_NEXT_VARIABLE		QSEE_CMD_UEFI(2)
+#define QSEE_CMD_UEFI_QUERY_VARIABLE_INFO	QSEE_CMD_UEFI(3)
+
+/**
+ * struct qsee_req_uefi_get_variable - Request for GetVariable command.
+ * @command_id:  The ID of the command. Must be %QSEE_CMD_UEFI_GET_VARIABLE.
+ * @length:      Length of the request in bytes, including this struct and any
+ *               parameters (name, GUID) stored after it as well as any padding
+ *               thereof for alignment.
+ * @name_offset: Offset from the start of this struct to where the variable
+ *               name is stored (as utf-16 string), in bytes.
+ * @name_size:   Size of the name parameter in bytes, including null-terminator.
+ * @guid_offset: Offset from the start of this struct to where the GUID
+ *               parameter is stored, in bytes.
+ * @guid_size:   Size of the GUID parameter in bytes, i.e. sizeof(efi_guid_t).
+ * @data_size:   Size of the output buffer, in bytes.
+ */
+struct qsee_req_uefi_get_variable {
+	u32 command_id;
+	u32 length;
+	u32 name_offset;
+	u32 name_size;
+	u32 guid_offset;
+	u32 guid_size;
+	u32 data_size;
+} __packed;
+
+/**
+ * struct qsee_rsp_uefi_get_variable - Response for GetVariable command.
+ * @command_id:  The ID of the command. Should be %QSEE_CMD_UEFI_GET_VARIABLE.
+ * @length:      Length of the response in bytes, including this struct and the
+ *               returned data.
+ * @status:      Status of this command.
+ * @attributes:  EFI variable attributes.
+ * @data_offset: Offset from the start of this struct to where the data is
+ *               stored, in bytes.
+ * @data_size:   Size of the returned data, in bytes. In case status indicates
+ *               that the buffer is too small, this will be the size required
+ *               to store the EFI variable data.
+ */
+struct qsee_rsp_uefi_get_variable {
+	u32 command_id;
+	u32 length;
+	u32 status;
+	u32 attributes;
+	u32 data_offset;
+	u32 data_size;
+} __packed;
+
+/**
+ * struct qsee_req_uefi_set_variable - Request for the SetVariable command.
+ * @command_id:  The ID of the command. Must be %QSEE_CMD_UEFI_SET_VARIABLE.
+ * @length:      Length of the request in bytes, including this struct and any
+ *               parameters (name, GUID, data) stored after it as well as any
+ *               padding thereof required for alignment.
+ * @name_offset: Offset from the start of this struct to where the variable
+ *               name is stored (as utf-16 string), in bytes.
+ * @name_size:   Size of the name parameter in bytes, including null-terminator.
+ * @guid_offset: Offset from the start of this struct to where the GUID
+ *               parameter is stored, in bytes.
+ * @guid_size:   Size of the GUID parameter in bytes, i.e. sizeof(efi_guid_t).
+ * @attributes:  The EFI variable attributes to set for this variable.
+ * @data_offset: Offset from the start of this struct to where the EFI variable
+ *               data is stored, in bytes.
+ * @data_size:   Size of EFI variable data, in bytes.
+ *
+ */
+struct qsee_req_uefi_set_variable {
+	u32 command_id;
+	u32 length;
+	u32 name_offset;
+	u32 name_size;
+	u32 guid_offset;
+	u32 guid_size;
+	u32 attributes;
+	u32 data_offset;
+	u32 data_size;
+} __packed;
+
+/**
+ * struct qsee_rsp_uefi_set_variable - Response for the SetVariable command.
+ * @command_id:  The ID of the command. Should be %QSEE_CMD_UEFI_SET_VARIABLE.
+ * @length:      The length of this response, i.e. the size of this struct in
+ *               bytes.
+ * @status:      Status of this command.
+ * @_unknown1:   Unknown response field.
+ * @_unknown2:   Unknown response field.
+ */
+struct qsee_rsp_uefi_set_variable {
+	u32 command_id;
+	u32 length;
+	u32 status;
+	u32 _unknown1;
+	u32 _unknown2;
+} __packed;
+
+/**
+ * struct qsee_req_uefi_get_next_variable - Request for the
+ * GetNextVariableName command.
+ * @command_id:  The ID of the command. Must be
+ *               %QSEE_CMD_UEFI_GET_NEXT_VARIABLE.
+ * @length:      Length of the request in bytes, including this struct and any
+ *               parameters (name, GUID) stored after it as well as any padding
+ *               thereof for alignment.
+ * @guid_offset: Offset from the start of this struct to where the GUID
+ *               parameter is stored, in bytes.
+ * @guid_size:   Size of the GUID parameter in bytes, i.e. sizeof(efi_guid_t).
+ * @name_offset: Offset from the start of this struct to where the variable
+ *               name is stored (as utf-16 string), in bytes.
+ * @name_size:   Size of the name parameter in bytes, including null-terminator.
+ */
+struct qsee_req_uefi_get_next_variable {
+	u32 command_id;
+	u32 length;
+	u32 guid_offset;
+	u32 guid_size;
+	u32 name_offset;
+	u32 name_size;
+} __packed;
+
+/**
+ * struct qsee_rsp_uefi_get_next_variable - Response for the
+ * GetNextVariableName command.
+ * @command_id:  The ID of the command. Should be
+ *               %QSEE_CMD_UEFI_GET_NEXT_VARIABLE.
+ * @length:      Length of the response in bytes, including this struct and any
+ *               parameters (name, GUID) stored after it as well as any padding
+ *               thereof for alignment.
+ * @status:      Status of this command.
+ * @guid_offset: Offset from the start of this struct to where the GUID
+ *               parameter is stored, in bytes.
+ * @guid_size:   Size of the GUID parameter in bytes, i.e. sizeof(efi_guid_t).
+ * @name_offset: Offset from the start of this struct to where the variable
+ *               name is stored (as utf-16 string), in bytes.
+ * @name_size:   Size of the name parameter in bytes, including null-terminator.
+ */
+struct qsee_rsp_uefi_get_next_variable {
+	u32 command_id;
+	u32 length;
+	u32 status;
+	u32 guid_offset;
+	u32 guid_size;
+	u32 name_offset;
+	u32 name_size;
+} __packed;
+
+/**
+ * struct qsee_req_uefi_query_variable_info - Response for the
+ * GetNextVariableName command.
+ * @command_id: The ID of the command. Must be
+ *              %QSEE_CMD_UEFI_QUERY_VARIABLE_INFO.
+ * @length:     The length of this request, i.e. the size of this struct in
+ *              bytes.
+ * @attributes: The storage attributes to query the info for.
+ */
+struct qsee_req_uefi_query_variable_info {
+	u32 command_id;
+	u32 length;
+	u32 attributes;
+} __packed;
+
+/**
+ * struct qsee_rsp_uefi_query_variable_info - Response for the
+ * GetNextVariableName command.
+ * @command_id:        The ID of the command. Must be
+ *                     %QSEE_CMD_UEFI_QUERY_VARIABLE_INFO.
+ * @length:            The length of this response, i.e. the size of this
+ *                     struct in bytes.
+ * @status:            Status of this command.
+ * @_pad:              Padding.
+ * @storage_space:     Full storage space size, in bytes.
+ * @remaining_space:   Free storage space available, in bytes.
+ * @max_variable_size: Maximum variable data size, in bytes.
+ */
+struct qsee_rsp_uefi_query_variable_info {
+	u32 command_id;
+	u32 length;
+	u32 status;
+	u32 _pad;
+	u64 storage_space;
+	u64 remaining_space;
+	u64 max_variable_size;
+} __packed;
+
+/* -- Alignment helpers ----------------------------------------------------- */
+
+/*
+ * Helper macro to ensure proper alignment of types (fields and arrays) when
+ * stored in some (contiguous) buffer.
+ *
+ * Note: The driver from which this one has been reverse-engineered expects an
+ * alignment of 8 bytes (64 bits) for GUIDs. Our definition of efi_guid_t,
+ * however, has an alignment of 4 byte (32 bits). So far, this seems to work
+ * fine here. See also the comment on the typedef of efi_guid_t.
+ */
+#define qcuefi_buf_align_fields(fields...)					\
+	({									\
+		size_t __len = 0;						\
+		fields								\
+		__len;								\
+	})
+
+#define __field_impl(size, align, offset)					\
+	({									\
+		size_t *__offset = (offset);					\
+		size_t __aligned;						\
+										\
+		__aligned = ALIGN(__len, align);				\
+		__len = __aligned + (size);					\
+										\
+		if (__offset)							\
+			*__offset = __aligned;					\
+	});
+
+#define __array_offs(type, count, offset)					\
+	__field_impl(sizeof(type) * (count), __alignof__(type), offset)
+
+#define __array(type, count)		__array_offs(type, count, NULL)
+#define __field_offs(type, offset)	__array_offs(type, 1, offset)
+#define __field(type)			__array_offs(type, 1, NULL)
+
+/* -- UEFI app interface. --------------------------------------------------- */
+
+struct qcuefi_client {
+	struct qseecom_client *client;
+	struct efivars efivars;
+};
+
+static struct device *qcuefi_dev(struct qcuefi_client *qcuefi)
+{
+	return &qcuefi->client->aux_dev.dev;
+}
+
+static efi_status_t qsee_uefi_status_to_efi(u32 status)
+{
+	u64 category = status & 0xf0000000;
+	u64 code = status & 0x0fffffff;
+
+	return category << (BITS_PER_LONG - 32) | code;
+}
+
+static efi_status_t qsee_uefi_get_variable(struct qcuefi_client *qcuefi, const efi_char16_t *name,
+					   const efi_guid_t *guid, u32 *attributes,
+					   unsigned long *data_size, void *data)
+{
+	struct qsee_req_uefi_get_variable *req_data;
+	struct qsee_rsp_uefi_get_variable *rsp_data;
+	unsigned long buffer_size = *data_size;
+	efi_status_t efi_status = EFI_SUCCESS;
+	unsigned long name_length;
+	size_t guid_offs;
+	size_t name_offs;
+	size_t req_size;
+	size_t rsp_size;
+	ssize_t status;
+
+	if (!name || !guid)
+		return EFI_INVALID_PARAMETER;
+
+	name_length = ucs2_strnlen(name, QSEE_MAX_NAME_LEN) + 1;
+	if (name_length > QSEE_MAX_NAME_LEN)
+		return EFI_INVALID_PARAMETER;
+
+	if (buffer_size && !data)
+		return EFI_INVALID_PARAMETER;
+
+	req_size = qcuefi_buf_align_fields(
+		__field(*req_data)
+		__array_offs(*name, name_length, &name_offs)
+		__field_offs(*guid, &guid_offs)
+	);
+
+	rsp_size = qcuefi_buf_align_fields(
+		__field(*rsp_data)
+		__array(u8, buffer_size)
+	);
+
+	req_data = kzalloc(req_size, GFP_KERNEL);
+	if (!req_data) {
+		efi_status = EFI_OUT_OF_RESOURCES;
+		goto out;
+	}
+
+	rsp_data = kzalloc(rsp_size, GFP_KERNEL);
+	if (!rsp_data) {
+		efi_status = EFI_OUT_OF_RESOURCES;
+		goto out_free_req;
+	}
+
+	req_data->command_id = QSEE_CMD_UEFI_GET_VARIABLE;
+	req_data->data_size = buffer_size;
+	req_data->name_offset = name_offs;
+	req_data->name_size = name_length * sizeof(*name);
+	req_data->guid_offset = guid_offs;
+	req_data->guid_size = sizeof(*guid);
+	req_data->length = req_size;
+
+	status = ucs2_strscpy(((void *)req_data) + req_data->name_offset, name, name_length);
+	if (status < 0)
+		return EFI_INVALID_PARAMETER;
+
+	memcpy(((void *)req_data) + req_data->guid_offset, guid, req_data->guid_size);
+
+	status = qcom_qseecom_app_send(qcuefi->client, req_data, req_size, rsp_data, rsp_size);
+	if (status) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->command_id != QSEE_CMD_UEFI_GET_VARIABLE) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->length < sizeof(*rsp_data)) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->status) {
+		dev_dbg(qcuefi_dev(qcuefi), "%s: uefisecapp error: 0x%x\n",
+			__func__, rsp_data->status);
+		efi_status = qsee_uefi_status_to_efi(rsp_data->status);
+
+		/* Update size and attributes in case buffer is too small. */
+		if (efi_status == EFI_BUFFER_TOO_SMALL) {
+			*data_size = rsp_data->data_size;
+			if (attributes)
+				*attributes = rsp_data->attributes;
+		}
+
+		goto out_free;
+	}
+
+	if (rsp_data->length > rsp_size) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->data_offset + rsp_data->data_size > rsp_data->length) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	/*
+	 * Note: We need to set attributes and data size even if the buffer is
+	 * too small and we won't copy any data. This is described in spec, so
+	 * that callers can either allocate a buffer properly (with two calls
+	 * to this function) or just read back attributes withouth having to
+	 * deal with that.
+	 *
+	 * Specifically:
+	 * - If we have a buffer size of zero and no buffer, just return the
+	 *   attributes, required size, and indicate success.
+	 * - If the buffer size is nonzero but too small, indicate that as an
+	 *   error.
+	 * - Otherwise, we are good to copy the data.
+	 *
+	 * Note that we have already ensured above that the buffer pointer is
+	 * non-NULL if its size is nonzero.
+	 */
+	*data_size = rsp_data->data_size;
+	if (attributes)
+		*attributes = rsp_data->attributes;
+
+	if (buffer_size == 0 && !data) {
+		efi_status = EFI_SUCCESS;
+		goto out_free;
+	}
+
+	if (buffer_size < rsp_data->data_size) {
+		efi_status = EFI_BUFFER_TOO_SMALL;
+		goto out_free;
+	}
+
+	memcpy(data, ((void *)rsp_data) + rsp_data->data_offset, rsp_data->data_size);
+
+out_free:
+	kfree(rsp_data);
+out_free_req:
+	kfree(req_data);
+out:
+	return efi_status;
+}
+
+static efi_status_t qsee_uefi_set_variable(struct qcuefi_client *qcuefi, const efi_char16_t *name,
+					   const efi_guid_t *guid, u32 attributes,
+					   unsigned long data_size, const void *data)
+{
+	struct qsee_req_uefi_set_variable *req_data;
+	struct qsee_rsp_uefi_set_variable *rsp_data;
+	efi_status_t efi_status = EFI_SUCCESS;
+	unsigned long name_length;
+	size_t name_offs;
+	size_t guid_offs;
+	size_t data_offs;
+	size_t req_size;
+	ssize_t status;
+
+	if (!name || !guid)
+		return EFI_INVALID_PARAMETER;
+
+	name_length = ucs2_strnlen(name, QSEE_MAX_NAME_LEN) + 1;
+	if (name_length > QSEE_MAX_NAME_LEN)
+		return EFI_INVALID_PARAMETER;
+
+	/*
+	 * Make sure we have some data if data_size is nonzero. Note that using
+	 * a size of zero is a valid use-case described in spec and deletes the
+	 * variable.
+	 */
+	if (data_size && !data)
+		return EFI_INVALID_PARAMETER;
+
+	req_size = qcuefi_buf_align_fields(
+		__field(*req_data)
+		__array_offs(*name, name_length, &name_offs)
+		__field_offs(*guid, &guid_offs)
+		__array_offs(u8, data_size, &data_offs)
+	);
+
+	req_data = kzalloc(req_size, GFP_KERNEL);
+	if (!req_data) {
+		efi_status = EFI_OUT_OF_RESOURCES;
+		goto out;
+	}
+
+	rsp_data = kzalloc(sizeof(*rsp_data), GFP_KERNEL);
+	if (!rsp_data) {
+		efi_status = EFI_OUT_OF_RESOURCES;
+		goto out_free_req;
+	}
+
+	req_data->command_id = QSEE_CMD_UEFI_SET_VARIABLE;
+	req_data->attributes = attributes;
+	req_data->name_offset = name_offs;
+	req_data->name_size = name_length * sizeof(*name);
+	req_data->guid_offset = guid_offs;
+	req_data->guid_size = sizeof(*guid);
+	req_data->data_offset = data_offs;
+	req_data->data_size = data_size;
+	req_data->length = req_size;
+
+	status = ucs2_strscpy(((void *)req_data) + req_data->name_offset, name, name_length);
+	if (status < 0)
+		return EFI_INVALID_PARAMETER;
+
+	memcpy(((void *)req_data) + req_data->guid_offset, guid, req_data->guid_size);
+
+	if (data_size)
+		memcpy(((void *)req_data) + req_data->data_offset, data, req_data->data_size);
+
+	status = qcom_qseecom_app_send(qcuefi->client, req_data, req_size, rsp_data,
+				       sizeof(*rsp_data));
+	if (status) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->command_id != QSEE_CMD_UEFI_SET_VARIABLE) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->length != sizeof(*rsp_data)) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->status) {
+		dev_dbg(qcuefi_dev(qcuefi), "%s: uefisecapp error: 0x%x\n",
+			__func__, rsp_data->status);
+		efi_status = qsee_uefi_status_to_efi(rsp_data->status);
+	}
+
+out_free:
+	kfree(rsp_data);
+out_free_req:
+	kfree(req_data);
+out:
+	return efi_status;
+}
+
+static efi_status_t qsee_uefi_get_next_variable(struct qcuefi_client *qcuefi,
+						unsigned long *name_size, efi_char16_t *name,
+						efi_guid_t *guid)
+{
+	struct qsee_req_uefi_get_next_variable *req_data;
+	struct qsee_rsp_uefi_get_next_variable *rsp_data;
+	efi_status_t efi_status = EFI_SUCCESS;
+	size_t guid_offs;
+	size_t name_offs;
+	size_t req_size;
+	size_t rsp_size;
+	ssize_t status;
+
+	if (!name_size || !name || !guid)
+		return EFI_INVALID_PARAMETER;
+
+	if (*name_size == 0)
+		return EFI_INVALID_PARAMETER;
+
+	req_size = qcuefi_buf_align_fields(
+		__field(*req_data)
+		__field_offs(*guid, &guid_offs)
+		__array_offs(*name, *name_size / sizeof(*name), &name_offs)
+	);
+
+	rsp_size = qcuefi_buf_align_fields(
+		__field(*rsp_data)
+		__field(*guid)
+		__array(*name, *name_size / sizeof(*name))
+	);
+
+	req_data = kzalloc(req_size, GFP_KERNEL);
+	if (!req_data) {
+		efi_status = EFI_OUT_OF_RESOURCES;
+		goto out;
+	}
+
+	rsp_data = kzalloc(rsp_size, GFP_KERNEL);
+	if (!rsp_data) {
+		efi_status = EFI_OUT_OF_RESOURCES;
+		goto out_free_req;
+	}
+
+	req_data->command_id = QSEE_CMD_UEFI_GET_NEXT_VARIABLE;
+	req_data->guid_offset = guid_offs;
+	req_data->guid_size = sizeof(*guid);
+	req_data->name_offset = name_offs;
+	req_data->name_size = *name_size;
+	req_data->length = req_size;
+
+	memcpy(((void *)req_data) + req_data->guid_offset, guid, req_data->guid_size);
+	status = ucs2_strscpy(((void *)req_data) + req_data->name_offset, name,
+			      *name_size / sizeof(*name));
+	if (status < 0)
+		return EFI_INVALID_PARAMETER;
+
+	status = qcom_qseecom_app_send(qcuefi->client, req_data, req_size, rsp_data, rsp_size);
+	if (status) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->command_id != QSEE_CMD_UEFI_GET_NEXT_VARIABLE) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->length < sizeof(*rsp_data)) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->status) {
+		dev_dbg(qcuefi_dev(qcuefi), "%s: uefisecapp error: 0x%x\n",
+			__func__, rsp_data->status);
+		efi_status = qsee_uefi_status_to_efi(rsp_data->status);
+
+		/*
+		 * If the buffer to hold the name is too small, update the
+		 * name_size with the required size, so that callers can
+		 * reallocate it accordingly.
+		 */
+		if (efi_status == EFI_BUFFER_TOO_SMALL)
+			*name_size = rsp_data->name_size;
+
+		goto out_free;
+	}
+
+	if (rsp_data->length > rsp_size) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->name_offset + rsp_data->name_size > rsp_data->length) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->guid_offset + rsp_data->guid_size > rsp_data->length) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->name_size > *name_size) {
+		*name_size = rsp_data->name_size;
+		efi_status = EFI_BUFFER_TOO_SMALL;
+		goto out_free;
+	}
+
+	if (rsp_data->guid_size != sizeof(*guid)) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	memcpy(guid, ((void *)rsp_data) + rsp_data->guid_offset, rsp_data->guid_size);
+	status = ucs2_strscpy(name, ((void *)rsp_data) + rsp_data->name_offset,
+			      rsp_data->name_size / sizeof(*name));
+	*name_size = rsp_data->name_size;
+
+	if (status < 0) {
+		/*
+		 * Return EFI_DEVICE_ERROR here because the buffer size should
+		 * have already been validated above, causing this function to
+		 * bail with EFI_BUFFER_TOO_SMALL.
+		 */
+		return EFI_DEVICE_ERROR;
+	}
+
+out_free:
+	kfree(rsp_data);
+out_free_req:
+	kfree(req_data);
+out:
+	return efi_status;
+}
+
+static efi_status_t qsee_uefi_query_variable_info(struct qcuefi_client *qcuefi, u32 attr,
+						  u64 *storage_space, u64 *remaining_space,
+						  u64 *max_variable_size)
+{
+	struct qsee_req_uefi_query_variable_info *req_data;
+	struct qsee_rsp_uefi_query_variable_info *rsp_data;
+	efi_status_t efi_status = EFI_SUCCESS;
+	int status;
+
+	req_data = kzalloc(sizeof(*req_data), GFP_KERNEL);
+	if (!req_data) {
+		efi_status = EFI_OUT_OF_RESOURCES;
+		goto out;
+	}
+
+	rsp_data = kzalloc(sizeof(*rsp_data), GFP_KERNEL);
+	if (!rsp_data) {
+		efi_status = EFI_OUT_OF_RESOURCES;
+		goto out_free_req;
+	}
+
+	req_data->command_id = QSEE_CMD_UEFI_QUERY_VARIABLE_INFO;
+	req_data->attributes = attr;
+	req_data->length = sizeof(*req_data);
+
+	status = qcom_qseecom_app_send(qcuefi->client, req_data, sizeof(*req_data), rsp_data,
+				       sizeof(*rsp_data));
+	if (status) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->command_id != QSEE_CMD_UEFI_QUERY_VARIABLE_INFO) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->length != sizeof(*rsp_data)) {
+		efi_status = EFI_DEVICE_ERROR;
+		goto out_free;
+	}
+
+	if (rsp_data->status) {
+		dev_dbg(qcuefi_dev(qcuefi), "%s: uefisecapp error: 0x%x\n",
+			__func__, rsp_data->status);
+		efi_status = qsee_uefi_status_to_efi(rsp_data->status);
+		goto out_free;
+	}
+
+	if (storage_space)
+		*storage_space = rsp_data->storage_space;
+
+	if (remaining_space)
+		*remaining_space = rsp_data->remaining_space;
+
+	if (max_variable_size)
+		*max_variable_size = rsp_data->max_variable_size;
+
+out_free:
+	kfree(rsp_data);
+out_free_req:
+	kfree(req_data);
+out:
+	return efi_status;
+}
+
+/* -- Global efivar interface. ---------------------------------------------- */
+
+static struct qcuefi_client *__qcuefi;
+static DEFINE_MUTEX(__qcuefi_lock);
+
+static int qcuefi_set_reference(struct qcuefi_client *qcuefi)
+{
+	mutex_lock(&__qcuefi_lock);
+
+	if (qcuefi && __qcuefi) {
+		mutex_unlock(&__qcuefi_lock);
+		return -EEXIST;
+	}
+
+	__qcuefi = qcuefi;
+
+	mutex_unlock(&__qcuefi_lock);
+	return 0;
+}
+
+static struct qcuefi_client *qcuefi_acquire(void)
+{
+	mutex_lock(&__qcuefi_lock);
+	return __qcuefi;
+}
+
+static void qcuefi_release(void)
+{
+	mutex_unlock(&__qcuefi_lock);
+}
+
+static efi_status_t qcuefi_get_variable(efi_char16_t *name, efi_guid_t *vendor, u32 *attr,
+					unsigned long *data_size, void *data)
+{
+	struct qcuefi_client *qcuefi;
+	efi_status_t status;
+
+	qcuefi = qcuefi_acquire();
+	if (!qcuefi)
+		return EFI_NOT_READY;
+
+	status = qsee_uefi_get_variable(qcuefi, name, vendor, attr, data_size, data);
+
+	qcuefi_release();
+	return status;
+}
+
+static efi_status_t qcuefi_set_variable(efi_char16_t *name, efi_guid_t *vendor,
+					u32 attr, unsigned long data_size, void *data)
+{
+	struct qcuefi_client *qcuefi;
+	efi_status_t status;
+
+	qcuefi = qcuefi_acquire();
+	if (!qcuefi)
+		return EFI_NOT_READY;
+
+	status = qsee_uefi_set_variable(qcuefi, name, vendor, attr, data_size, data);
+
+	qcuefi_release();
+	return status;
+}
+
+static efi_status_t qcuefi_get_next_variable(unsigned long *name_size, efi_char16_t *name,
+					     efi_guid_t *vendor)
+{
+	struct qcuefi_client *qcuefi;
+	efi_status_t status;
+
+	qcuefi = qcuefi_acquire();
+	if (!qcuefi)
+		return EFI_NOT_READY;
+
+	status = qsee_uefi_get_next_variable(qcuefi, name_size, name, vendor);
+
+	qcuefi_release();
+	return status;
+}
+
+static efi_status_t qcuefi_query_variable_info(u32 attr, u64 *storage_space, u64 *remaining_space,
+					       u64 *max_variable_size)
+{
+	struct qcuefi_client *qcuefi;
+	efi_status_t status;
+
+	qcuefi = qcuefi_acquire();
+	if (!qcuefi)
+		return EFI_NOT_READY;
+
+	status = qsee_uefi_query_variable_info(qcuefi, attr, storage_space, remaining_space,
+					       max_variable_size);
+
+	qcuefi_release();
+	return status;
+}
+
+static const struct efivar_operations qcom_efivar_ops = {
+	.get_variable = qcuefi_get_variable,
+	.set_variable = qcuefi_set_variable,
+	.get_next_variable = qcuefi_get_next_variable,
+	.query_variable_info = qcuefi_query_variable_info,
+};
+
+/* -- Driver setup. --------------------------------------------------------- */
+
+static int qcom_uefisecapp_probe(struct auxiliary_device *aux_dev,
+				 const struct auxiliary_device_id *aux_dev_id)
+{
+	struct qcuefi_client *qcuefi;
+	int status;
+
+	qcuefi = devm_kzalloc(&aux_dev->dev, sizeof(*qcuefi), GFP_KERNEL);
+	if (!qcuefi)
+		return -ENOMEM;
+
+	qcuefi->client = container_of(aux_dev, struct qseecom_client, aux_dev);
+
+	auxiliary_set_drvdata(aux_dev, qcuefi);
+	status = qcuefi_set_reference(qcuefi);
+	if (status)
+		return status;
+
+	status = efivars_register(&qcuefi->efivars, &qcom_efivar_ops);
+	if (status)
+		qcuefi_set_reference(NULL);
+
+	return status;
+}
+
+static void qcom_uefisecapp_remove(struct auxiliary_device *aux_dev)
+{
+	struct qcuefi_client *qcuefi = auxiliary_get_drvdata(aux_dev);
+
+	efivars_unregister(&qcuefi->efivars);
+	qcuefi_set_reference(NULL);
+}
+
+static const struct auxiliary_device_id qcom_uefisecapp_id_table[] = {
+	{ .name = "qcom_qseecom.uefisecapp" },
+	{}
+};
+MODULE_DEVICE_TABLE(auxiliary, qcom_uefisecapp_id_table);
+
+static struct auxiliary_driver qcom_uefisecapp_driver = {
+	.probe = qcom_uefisecapp_probe,
+	.remove = qcom_uefisecapp_remove,
+	.id_table = qcom_uefisecapp_id_table,
+	.driver = {
+		.name = "qcom_qseecom_uefisecapp",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+module_auxiliary_driver(qcom_uefisecapp_driver);
+
+MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
+MODULE_DESCRIPTION("Client driver for Qualcomm SEE UEFI Secure App");
+MODULE_LICENSE("GPL");