Contributors: 7
Author Tokens Token Proportion Commits Commit Proportion
Maximilian Luz 2699 91.24% 3 25.00%
Bartosz Golaszewski 200 6.76% 4 33.33%
Andy Gross 40 1.35% 1 8.33%
John Stultz 6 0.20% 1 8.33%
Dan Carpenter 6 0.20% 1 8.33%
Jordan Crouse 5 0.17% 1 8.33%
Björn Andersson 2 0.07% 1 8.33%
Total 2958 12 


// 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/sizes.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/ucs2_string.h>

#include <linux/firmware/qcom/qcom_qseecom.h>
#include <linux/firmware/qcom/qcom_scm.h>
#include <linux/firmware/qcom/qcom_tzmem.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.
 *
 * Note: It looks like uefisecapp is quite picky about how the memory passed to
 * it is structured and aligned. In particular the request/response setup used
 * for QSEE_CMD_UEFI_GET_VARIABLE. While qcom_qseecom_app_send(), in theory,
 * accepts separate buffers/addresses for the request and response parts, in
 * practice, however, it seems to expect them to be both part of a larger
 * contiguous block. We initially allocated separate buffers for the request
 * and response but this caused the QSEE_CMD_UEFI_GET_VARIABLE command to
 * either not write any response to the response buffer or outright crash the
 * device. Therefore, we now allocate a single contiguous block of DMA memory
 * for both and properly align the data using the macros below. In particular,
 * request and response structs are aligned at 8 byte (via __reqdata_offs()),
 * following the driver that this has been reverse-engineered from.
 */
#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_offs_aligned(type, count, align, offset)			\
	__field_impl(sizeof(type) * (count), align, offset)

#define __reqdata_offs(size, offset)						\
	__array_offs_aligned(u8, size, 8, 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;
	struct qcom_tzmem_pool *mempool;
};

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;
	void *cmd_buf __free(qcom_tzmem) = NULL;
	unsigned long buffer_size = *data_size;
	unsigned long name_length;
	efi_status_t efi_status;
	size_t cmd_buf_size;
	size_t guid_offs;
	size_t name_offs;
	size_t req_size;
	size_t rsp_size;
	size_t req_offs;
	size_t rsp_offs;
	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)
	);

	cmd_buf_size = qcuefi_buf_align_fields(
		__reqdata_offs(req_size, &req_offs)
		__reqdata_offs(rsp_size, &rsp_offs)
	);

	cmd_buf = qcom_tzmem_alloc(qcuefi->mempool, cmd_buf_size, GFP_KERNEL);
	if (!cmd_buf)
		return EFI_OUT_OF_RESOURCES;

	req_data = cmd_buf + req_offs;
	rsp_data = cmd_buf + rsp_offs;

	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,
				       cmd_buf + req_offs, req_size,
				       cmd_buf + rsp_offs, rsp_size);
	if (status)
		return EFI_DEVICE_ERROR;

	if (rsp_data->command_id != QSEE_CMD_UEFI_GET_VARIABLE)
		return EFI_DEVICE_ERROR;

	if (rsp_data->length < sizeof(*rsp_data))
		return EFI_DEVICE_ERROR;

	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;
		}

		return qsee_uefi_status_to_efi(rsp_data->status);
	}

	if (rsp_data->length > rsp_size)
		return EFI_DEVICE_ERROR;

	if (rsp_data->data_offset + rsp_data->data_size > rsp_data->length)
		return EFI_DEVICE_ERROR;

	/*
	 * 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)
		return EFI_SUCCESS;

	if (buffer_size < rsp_data->data_size)
		return EFI_BUFFER_TOO_SMALL;

	memcpy(data, ((void *)rsp_data) + rsp_data->data_offset, rsp_data->data_size);

	return EFI_SUCCESS;
}

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;
	void *cmd_buf __free(qcom_tzmem) = NULL;
	unsigned long name_length;
	size_t cmd_buf_size;
	size_t name_offs;
	size_t guid_offs;
	size_t data_offs;
	size_t req_size;
	size_t req_offs;
	size_t rsp_offs;
	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)
	);

	cmd_buf_size = qcuefi_buf_align_fields(
		__reqdata_offs(req_size, &req_offs)
		__reqdata_offs(sizeof(*rsp_data), &rsp_offs)
	);

	cmd_buf = qcom_tzmem_alloc(qcuefi->mempool, cmd_buf_size, GFP_KERNEL);
	if (!cmd_buf)
		return EFI_OUT_OF_RESOURCES;

	req_data = cmd_buf + req_offs;
	rsp_data = cmd_buf + rsp_offs;

	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,
				       cmd_buf + req_offs, req_size,
				       cmd_buf + rsp_offs, sizeof(*rsp_data));
	if (status)
		return EFI_DEVICE_ERROR;

	if (rsp_data->command_id != QSEE_CMD_UEFI_SET_VARIABLE)
		return EFI_DEVICE_ERROR;

	if (rsp_data->length != sizeof(*rsp_data))
		return EFI_DEVICE_ERROR;

	if (rsp_data->status) {
		dev_dbg(qcuefi_dev(qcuefi), "%s: uefisecapp error: 0x%x\n",
			__func__, rsp_data->status);
		return qsee_uefi_status_to_efi(rsp_data->status);
	}

	return EFI_SUCCESS;
}

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;
	void *cmd_buf __free(qcom_tzmem) = NULL;
	efi_status_t efi_status;
	size_t cmd_buf_size;
	size_t guid_offs;
	size_t name_offs;
	size_t req_size;
	size_t rsp_size;
	size_t req_offs;
	size_t rsp_offs;
	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))
	);

	cmd_buf_size = qcuefi_buf_align_fields(
		__reqdata_offs(req_size, &req_offs)
		__reqdata_offs(rsp_size, &rsp_offs)
	);

	cmd_buf = qcom_tzmem_alloc(qcuefi->mempool, cmd_buf_size, GFP_KERNEL);
	if (!cmd_buf)
		return EFI_OUT_OF_RESOURCES;

	req_data = cmd_buf + req_offs;
	rsp_data = cmd_buf + rsp_offs;

	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,
				       cmd_buf + req_offs, req_size,
				       cmd_buf + rsp_offs, rsp_size);
	if (status)
		return EFI_DEVICE_ERROR;

	if (rsp_data->command_id != QSEE_CMD_UEFI_GET_NEXT_VARIABLE)
		return EFI_DEVICE_ERROR;

	if (rsp_data->length < sizeof(*rsp_data))
		return EFI_DEVICE_ERROR;

	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;

		return efi_status;
	}

	if (rsp_data->length > rsp_size)
		return EFI_DEVICE_ERROR;

	if (rsp_data->name_offset + rsp_data->name_size > rsp_data->length)
		return EFI_DEVICE_ERROR;

	if (rsp_data->guid_offset + rsp_data->guid_size > rsp_data->length)
		return EFI_DEVICE_ERROR;

	if (rsp_data->name_size > *name_size) {
		*name_size = rsp_data->name_size;
		return EFI_BUFFER_TOO_SMALL;
	}

	if (rsp_data->guid_size != sizeof(*guid))
		return EFI_DEVICE_ERROR;

	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;

	return EFI_SUCCESS;
}

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;
	void *cmd_buf __free(qcom_tzmem) = NULL;
	size_t cmd_buf_size;
	size_t req_offs;
	size_t rsp_offs;
	int status;

	cmd_buf_size = qcuefi_buf_align_fields(
		__reqdata_offs(sizeof(*req_data), &req_offs)
		__reqdata_offs(sizeof(*rsp_data), &rsp_offs)
	);

	cmd_buf = qcom_tzmem_alloc(qcuefi->mempool, cmd_buf_size, GFP_KERNEL);
	if (!cmd_buf)
		return EFI_OUT_OF_RESOURCES;

	req_data = cmd_buf + req_offs;
	rsp_data = cmd_buf + rsp_offs;

	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,
				       cmd_buf + req_offs, sizeof(*req_data),
				       cmd_buf + rsp_offs, sizeof(*rsp_data));
	if (status)
		return EFI_DEVICE_ERROR;

	if (rsp_data->command_id != QSEE_CMD_UEFI_QUERY_VARIABLE_INFO)
		return EFI_DEVICE_ERROR;

	if (rsp_data->length != sizeof(*rsp_data))
		return EFI_DEVICE_ERROR;

	if (rsp_data->status) {
		dev_dbg(qcuefi_dev(qcuefi), "%s: uefisecapp error: 0x%x\n",
			__func__, rsp_data->status);
		return qsee_uefi_status_to_efi(rsp_data->status);
	}

	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;

	return EFI_SUCCESS;
}

/* -- 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);
	if (!__qcuefi) {
		mutex_unlock(&__qcuefi_lock);
		return NULL;
	}
	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 qcom_tzmem_pool_config pool_config;
	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);

	memset(&pool_config, 0, sizeof(pool_config));
	pool_config.initial_size = SZ_4K;
	pool_config.policy = QCOM_TZMEM_POLICY_MULTIPLIER;
	pool_config.increment = 2;
	pool_config.max_size = SZ_256K;

	qcuefi->mempool = devm_qcom_tzmem_pool_new(&aux_dev->dev, &pool_config);
	if (IS_ERR(qcuefi->mempool))
		return PTR_ERR(qcuefi->mempool);

	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");