--- /dev/null
+// 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");