accel/qaic/qaic_control.c

// SPDX-License-Identifier: GPL-2.0-only

/* Copyright (c) 2019-2021, The Linux Foundation. All rights reserved. */
/* Copyright (c) 2021-2023 Qualcomm Innovation Center, Inc. All rights reserved. */

#include <asm/byteorder.h>
#include <linux/completion.h>
#include <linux/crc32.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/mhi.h>
#include <linux/mm.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/scatterlist.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/workqueue.h>
#include <linux/wait.h>
#include <drm/drm_device.h>
#include <drm/drm_file.h>
#include <uapi/drm/qaic_accel.h>

#include "qaic.h"

#define MANAGE_MAGIC_NUMBER		((__force __le32)0x43494151) /* "QAIC" in little endian */
#define QAIC_DBC_Q_GAP			SZ_256
#define QAIC_DBC_Q_BUF_ALIGN		SZ_4K
#define QAIC_MANAGE_EXT_MSG_LENGTH	SZ_64K /* Max DMA message length */
#define QAIC_WRAPPER_MAX_SIZE		SZ_4K
#define QAIC_MHI_RETRY_WAIT_MS		100
#define QAIC_MHI_RETRY_MAX		20

static unsigned int control_resp_timeout_s = 60; /* 60 sec default */
module_param(control_resp_timeout_s, uint, 0600);
MODULE_PARM_DESC(control_resp_timeout_s, "Timeout for NNC responses from QSM");

struct manage_msg {
	u32 len;
	u32 count;
	u8 data[];
};

/*
 * wire encoding structures for the manage protocol.
 * All fields are little endian on the wire
 */
struct wire_msg_hdr {
	__le32 crc32; /* crc of everything following this field in the message */
	__le32 magic_number;
	__le32 sequence_number;
	__le32 len; /* length of this message */
	__le32 count; /* number of transactions in this message */
	__le32 handle; /* unique id to track the resources consumed */
	__le32 partition_id; /* partition id for the request (signed) */
	__le32 padding; /* must be 0 */
} __packed;

struct wire_msg {
	struct wire_msg_hdr hdr;
	u8 data[];
} __packed;

struct wire_trans_hdr {
	__le32 type;
	__le32 len;
} __packed;

/* Each message sent from driver to device are organized in a list of wrapper_msg */
struct wrapper_msg {
	struct list_head list;
	struct kref ref_count;
	u32 len; /* length of data to transfer */
	struct wrapper_list *head;
	union {
		struct wire_msg msg;
		struct wire_trans_hdr trans;
	};
};

struct wrapper_list {
	struct list_head list;
	spinlock_t lock; /* Protects the list state during additions and removals */
};

struct wire_trans_passthrough {
	struct wire_trans_hdr hdr;
	u8 data[];
} __packed;

struct wire_addr_size_pair {
	__le64 addr;
	__le64 size;
} __packed;

struct wire_trans_dma_xfer {
	struct wire_trans_hdr hdr;
	__le32 tag;
	__le32 count;
	__le32 dma_chunk_id;
	__le32 padding;
	struct wire_addr_size_pair data[];
} __packed;

/* Initiated by device to continue the DMA xfer of a large piece of data */
struct wire_trans_dma_xfer_cont {
	struct wire_trans_hdr hdr;
	__le32 dma_chunk_id;
	__le32 padding;
	__le64 xferred_size;
} __packed;

struct wire_trans_activate_to_dev {
	struct wire_trans_hdr hdr;
	__le64 req_q_addr;
	__le64 rsp_q_addr;
	__le32 req_q_size;
	__le32 rsp_q_size;
	__le32 buf_len;
	__le32 options; /* unused, but BIT(16) has meaning to the device */
} __packed;

struct wire_trans_activate_from_dev {
	struct wire_trans_hdr hdr;
	__le32 status;
	__le32 dbc_id;
	__le64 options; /* unused */
} __packed;

struct wire_trans_deactivate_from_dev {
	struct wire_trans_hdr hdr;
	__le32 status;
	__le32 dbc_id;
} __packed;

struct wire_trans_terminate_to_dev {
	struct wire_trans_hdr hdr;
	__le32 handle;
	__le32 padding;
} __packed;

struct wire_trans_terminate_from_dev {
	struct wire_trans_hdr hdr;
	__le32 status;
	__le32 padding;
} __packed;

struct wire_trans_status_to_dev {
	struct wire_trans_hdr hdr;
} __packed;

struct wire_trans_status_from_dev {
	struct wire_trans_hdr hdr;
	__le16 major;
	__le16 minor;
	__le32 status;
	__le64 status_flags;
} __packed;

struct wire_trans_validate_part_to_dev {
	struct wire_trans_hdr hdr;
	__le32 part_id;
	__le32 padding;
} __packed;

struct wire_trans_validate_part_from_dev {
	struct wire_trans_hdr hdr;
	__le32 status;
	__le32 padding;
} __packed;

struct xfer_queue_elem {
	/*
	 * Node in list of ongoing transfer request on control channel.
	 * Maintained by root device struct.
	 */
	struct list_head list;
	/* Sequence number of this transfer request */
	u32 seq_num;
	/* This is used to wait on until completion of transfer request */
	struct completion xfer_done;
	/* Received data from device */
	void *buf;
};

struct dma_xfer {
	/* Node in list of DMA transfers which is used for cleanup */
	struct list_head list;
	/* SG table of memory used for DMA */
	struct sg_table *sgt;
	/* Array pages used for DMA */
	struct page **page_list;
	/* Number of pages used for DMA */
	unsigned long nr_pages;
};

struct ioctl_resources {
	/* List of all DMA transfers which is used later for cleanup */
	struct list_head dma_xfers;
	/* Base address of request queue which belongs to a DBC */
	void *buf;
	/*
	 * Base bus address of request queue which belongs to a DBC. Response
	 * queue base bus address can be calculated by adding size of request
	 * queue to base bus address of request queue.
	 */
	dma_addr_t dma_addr;
	/* Total size of request queue and response queue in byte */
	u32 total_size;
	/* Total number of elements that can be queued in each of request and response queue */
	u32 nelem;
	/* Base address of response queue which belongs to a DBC */
	void *rsp_q_base;
	/* Status of the NNC message received */
	u32 status;
	/* DBC id of the DBC received from device */
	u32 dbc_id;
	/*
	 * DMA transfer request messages can be big in size and it may not be
	 * possible to send them in one shot. In such cases the messages are
	 * broken into chunks, this field stores ID of such chunks.
	 */
	u32 dma_chunk_id;
	/* Total number of bytes transferred for a DMA xfer request */
	u64 xferred_dma_size;
	/* Header of transaction message received from user. Used during DMA xfer request. */
	void *trans_hdr;
};

struct resp_work {
	struct work_struct work;
	struct qaic_device *qdev;
	void *buf;
};

/*
 * Since we're working with little endian messages, its useful to be able to
 * increment without filling a whole line with conversions back and forth just
 * to add one(1) to a message count.
 */
static __le32 incr_le32(__le32 val)
{
	return cpu_to_le32(le32_to_cpu(val) + 1);
}

static u32 gen_crc(void *msg)
{
	struct wrapper_list *wrappers = msg;
	struct wrapper_msg *w;
	u32 crc = ~0;

	list_for_each_entry(w, &wrappers->list, list)
		crc = crc32(crc, &w->msg, w->len);

	return crc ^ ~0;
}

static u32 gen_crc_stub(void *msg)
{
	return 0;
}

static bool valid_crc(void *msg)
{
	struct wire_msg_hdr *hdr = msg;
	bool ret;
	u32 crc;

	/*
	 * The output of this algorithm is always converted to the native
	 * endianness.
	 */
	crc = le32_to_cpu(hdr->crc32);
	hdr->crc32 = 0;
	ret = (crc32(~0, msg, le32_to_cpu(hdr->len)) ^ ~0) == crc;
	hdr->crc32 = cpu_to_le32(crc);
	return ret;
}

static bool valid_crc_stub(void *msg)
{
	return true;
}

static void free_wrapper(struct kref *ref)
{
	struct wrapper_msg *wrapper = container_of(ref, struct wrapper_msg, ref_count);

	list_del(&wrapper->list);
	kfree(wrapper);
}

static void save_dbc_buf(struct qaic_device *qdev, struct ioctl_resources *resources,
			 struct qaic_user *usr)
{
	u32 dbc_id = resources->dbc_id;

	if (resources->buf) {
		wait_event_interruptible(qdev->dbc[dbc_id].dbc_release, !qdev->dbc[dbc_id].in_use);
		qdev->dbc[dbc_id].req_q_base = resources->buf;
		qdev->dbc[dbc_id].rsp_q_base = resources->rsp_q_base;
		qdev->dbc[dbc_id].dma_addr = resources->dma_addr;
		qdev->dbc[dbc_id].total_size = resources->total_size;
		qdev->dbc[dbc_id].nelem = resources->nelem;
		enable_dbc(qdev, dbc_id, usr);
		qdev->dbc[dbc_id].in_use = true;
		resources->buf = NULL;
	}
}

static void free_dbc_buf(struct qaic_device *qdev, struct ioctl_resources *resources)
{
	if (resources->buf)
		dma_free_coherent(&qdev->pdev->dev, resources->total_size, resources->buf,
				  resources->dma_addr);
	resources->buf = NULL;
}

static void free_dma_xfers(struct qaic_device *qdev, struct ioctl_resources *resources)
{
	struct dma_xfer *xfer;
	struct dma_xfer *x;
	int i;

	list_for_each_entry_safe(xfer, x, &resources->dma_xfers, list) {
		dma_unmap_sgtable(&qdev->pdev->dev, xfer->sgt, DMA_TO_DEVICE, 0);
		sg_free_table(xfer->sgt);
		kfree(xfer->sgt);
		for (i = 0; i < xfer->nr_pages; ++i)
			put_page(xfer->page_list[i]);
		kfree(xfer->page_list);
		list_del(&xfer->list);
		kfree(xfer);
	}
}

static struct wrapper_msg *add_wrapper(struct wrapper_list *wrappers, u32 size)
{
	struct wrapper_msg *w = kzalloc(size, GFP_KERNEL);

	if (!w)
		return NULL;
	list_add_tail(&w->list, &wrappers->list);
	kref_init(&w->ref_count);
	w->head = wrappers;
	return w;
}

static int encode_passthrough(struct qaic_device *qdev, void *trans, struct wrapper_list *wrappers,
			      u32 *user_len)
{
	struct qaic_manage_trans_passthrough *in_trans = trans;
	struct wire_trans_passthrough *out_trans;
	struct wrapper_msg *trans_wrapper;
	struct wrapper_msg *wrapper;
	struct wire_msg *msg;
	u32 msg_hdr_len;

	wrapper = list_first_entry(&wrappers->list, struct wrapper_msg, list);
	msg = &wrapper->msg;
	msg_hdr_len = le32_to_cpu(msg->hdr.len);

	if (in_trans->hdr.len % 8 != 0)
		return -EINVAL;

	if (msg_hdr_len + in_trans->hdr.len > QAIC_MANAGE_EXT_MSG_LENGTH)
		return -ENOSPC;

	trans_wrapper = add_wrapper(wrappers,
				    offsetof(struct wrapper_msg, trans) + in_trans->hdr.len);
	if (!trans_wrapper)
		return -ENOMEM;
	trans_wrapper->len = in_trans->hdr.len;
	out_trans = (struct wire_trans_passthrough *)&trans_wrapper->trans;

	memcpy(out_trans->data, in_trans->data, in_trans->hdr.len - sizeof(in_trans->hdr));
	msg->hdr.len = cpu_to_le32(msg_hdr_len + in_trans->hdr.len);
	msg->hdr.count = incr_le32(msg->hdr.count);
	*user_len += in_trans->hdr.len;
	out_trans->hdr.type = cpu_to_le32(QAIC_TRANS_PASSTHROUGH_TO_DEV);
	out_trans->hdr.len = cpu_to_le32(in_trans->hdr.len);

	return 0;
}

/* returns error code for failure, 0 if enough pages alloc'd, 1 if dma_cont is needed */
static int find_and_map_user_pages(struct qaic_device *qdev,
				   struct qaic_manage_trans_dma_xfer *in_trans,
				   struct ioctl_resources *resources, struct dma_xfer *xfer)
{
	unsigned long need_pages;
	struct page **page_list;
	unsigned long nr_pages;
	struct sg_table *sgt;
	u64 xfer_start_addr;
	int ret;
	int i;

	xfer_start_addr = in_trans->addr + resources->xferred_dma_size;

	need_pages = DIV_ROUND_UP(in_trans->size + offset_in_page(xfer_start_addr) -
				  resources->xferred_dma_size, PAGE_SIZE);

	nr_pages = need_pages;

	while (1) {
		page_list = kmalloc_array(nr_pages, sizeof(*page_list), GFP_KERNEL | __GFP_NOWARN);
		if (!page_list) {
			nr_pages = nr_pages / 2;
			if (!nr_pages)
				return -ENOMEM;
		} else {
			break;
		}
	}

	ret = get_user_pages_fast(xfer_start_addr, nr_pages, 0, page_list);
	if (ret < 0 || ret != nr_pages) {
		ret = -EFAULT;
		goto free_page_list;
	}

	sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
	if (!sgt) {
		ret = -ENOMEM;
		goto put_pages;
	}

	ret = sg_alloc_table_from_pages(sgt, page_list, nr_pages,
					offset_in_page(xfer_start_addr),
					in_trans->size - resources->xferred_dma_size, GFP_KERNEL);
	if (ret) {
		ret = -ENOMEM;
		goto free_sgt;
	}

	ret = dma_map_sgtable(&qdev->pdev->dev, sgt, DMA_TO_DEVICE, 0);
	if (ret)
		goto free_table;

	xfer->sgt = sgt;
	xfer->page_list = page_list;
	xfer->nr_pages = nr_pages;

	return need_pages > nr_pages ? 1 : 0;

free_table:
	sg_free_table(sgt);
free_sgt:
	kfree(sgt);
put_pages:
	for (i = 0; i < nr_pages; ++i)
		put_page(page_list[i]);
free_page_list:
	kfree(page_list);
	return ret;
}

/* returns error code for failure, 0 if everything was encoded, 1 if dma_cont is needed */
static int encode_addr_size_pairs(struct dma_xfer *xfer, struct wrapper_list *wrappers,
				  struct ioctl_resources *resources, u32 msg_hdr_len, u32 *size,
				  struct wire_trans_dma_xfer **out_trans)
{
	struct wrapper_msg *trans_wrapper;
	struct sg_table *sgt = xfer->sgt;
	struct wire_addr_size_pair *asp;
	struct scatterlist *sg;
	struct wrapper_msg *w;
	unsigned int dma_len;
	u64 dma_chunk_len;
	void *boundary;
	int nents_dma;
	int nents;
	int i;

	nents = sgt->nents;
	nents_dma = nents;
	*size = QAIC_MANAGE_EXT_MSG_LENGTH - msg_hdr_len - sizeof(**out_trans);
	for_each_sgtable_sg(sgt, sg, i) {
		*size -= sizeof(*asp);
		/* Save 1K for possible follow-up transactions. */
		if (*size < SZ_1K) {
			nents_dma = i;
			break;
		}
	}

	trans_wrapper = add_wrapper(wrappers, QAIC_WRAPPER_MAX_SIZE);
	if (!trans_wrapper)
		return -ENOMEM;
	*out_trans = (struct wire_trans_dma_xfer *)&trans_wrapper->trans;

	asp = (*out_trans)->data;
	boundary = (void *)trans_wrapper + QAIC_WRAPPER_MAX_SIZE;
	*size = 0;

	dma_len = 0;
	w = trans_wrapper;
	dma_chunk_len = 0;
	for_each_sg(sgt->sgl, sg, nents_dma, i) {
		asp->size = cpu_to_le64(dma_len);
		dma_chunk_len += dma_len;
		if (dma_len) {
			asp++;
			if ((void *)asp + sizeof(*asp) > boundary) {
				w->len = (void *)asp - (void *)&w->msg;
				*size += w->len;
				w = add_wrapper(wrappers, QAIC_WRAPPER_MAX_SIZE);
				if (!w)
					return -ENOMEM;
				boundary = (void *)w + QAIC_WRAPPER_MAX_SIZE;
				asp = (struct wire_addr_size_pair *)&w->msg;
			}
		}
		asp->addr = cpu_to_le64(sg_dma_address(sg));
		dma_len = sg_dma_len(sg);
	}
	/* finalize the last segment */
	asp->size = cpu_to_le64(dma_len);
	w->len = (void *)asp + sizeof(*asp) - (void *)&w->msg;
	*size += w->len;
	dma_chunk_len += dma_len;
	resources->xferred_dma_size += dma_chunk_len;

	return nents_dma < nents ? 1 : 0;
}

static void cleanup_xfer(struct qaic_device *qdev, struct dma_xfer *xfer)
{
	int i;

	dma_unmap_sgtable(&qdev->pdev->dev, xfer->sgt, DMA_TO_DEVICE, 0);
	sg_free_table(xfer->sgt);
	kfree(xfer->sgt);
	for (i = 0; i < xfer->nr_pages; ++i)
		put_page(xfer->page_list[i]);
	kfree(xfer->page_list);
}

static int encode_dma(struct qaic_device *qdev, void *trans, struct wrapper_list *wrappers,
		      u32 *user_len, struct ioctl_resources *resources, struct qaic_user *usr)
{
	struct qaic_manage_trans_dma_xfer *in_trans = trans;
	struct wire_trans_dma_xfer *out_trans;
	struct wrapper_msg *wrapper;
	struct dma_xfer *xfer;
	struct wire_msg *msg;
	bool need_cont_dma;
	u32 msg_hdr_len;
	u32 size;
	int ret;

	wrapper = list_first_entry(&wrappers->list, struct wrapper_msg, list);
	msg = &wrapper->msg;
	msg_hdr_len = le32_to_cpu(msg->hdr.len);

	if (msg_hdr_len > (UINT_MAX - QAIC_MANAGE_EXT_MSG_LENGTH))
		return -EINVAL;

	/* There should be enough space to hold at least one ASP entry. */
	if (msg_hdr_len + sizeof(*out_trans) + sizeof(struct wire_addr_size_pair) >
	    QAIC_MANAGE_EXT_MSG_LENGTH)
		return -ENOMEM;

	if (in_trans->addr + in_trans->size < in_trans->addr || !in_trans->size)
		return -EINVAL;

	xfer = kmalloc(sizeof(*xfer), GFP_KERNEL);
	if (!xfer)
		return -ENOMEM;

	ret = find_and_map_user_pages(qdev, in_trans, resources, xfer);
	if (ret < 0)
		goto free_xfer;

	need_cont_dma = (bool)ret;

	ret = encode_addr_size_pairs(xfer, wrappers, resources, msg_hdr_len, &size, &out_trans);
	if (ret < 0)
		goto cleanup_xfer;

	need_cont_dma = need_cont_dma || (bool)ret;

	msg->hdr.len = cpu_to_le32(msg_hdr_len + size);
	msg->hdr.count = incr_le32(msg->hdr.count);

	out_trans->hdr.type = cpu_to_le32(QAIC_TRANS_DMA_XFER_TO_DEV);
	out_trans->hdr.len = cpu_to_le32(size);
	out_trans->tag = cpu_to_le32(in_trans->tag);
	out_trans->count = cpu_to_le32((size - sizeof(*out_trans)) /
								sizeof(struct wire_addr_size_pair));

	*user_len += in_trans->hdr.len;

	if (resources->dma_chunk_id) {
		out_trans->dma_chunk_id = cpu_to_le32(resources->dma_chunk_id);
	} else if (need_cont_dma) {
		while (resources->dma_chunk_id == 0)
			resources->dma_chunk_id = atomic_inc_return(&usr->chunk_id);

		out_trans->dma_chunk_id = cpu_to_le32(resources->dma_chunk_id);
	}
	resources->trans_hdr = trans;

	list_add(&xfer->list, &resources->dma_xfers);
	return 0;

cleanup_xfer:
	cleanup_xfer(qdev, xfer);
free_xfer:
	kfree(xfer);
	return ret;
}

static int encode_activate(struct qaic_device *qdev, void *trans, struct wrapper_list *wrappers,
			   u32 *user_len, struct ioctl_resources *resources)
{
	struct qaic_manage_trans_activate_to_dev *in_trans = trans;
	struct wire_trans_activate_to_dev *out_trans;
	struct wrapper_msg *trans_wrapper;
	struct wrapper_msg *wrapper;
	struct wire_msg *msg;
	dma_addr_t dma_addr;
	u32 msg_hdr_len;
	void *buf;
	u32 nelem;
	u32 size;
	int ret;

	wrapper = list_first_entry(&wrappers->list, struct wrapper_msg, list);
	msg = &wrapper->msg;
	msg_hdr_len = le32_to_cpu(msg->hdr.len);

	if (msg_hdr_len + sizeof(*out_trans) > QAIC_MANAGE_MAX_MSG_LENGTH)
		return -ENOSPC;

	if (!in_trans->queue_size)
		return -EINVAL;

	if (in_trans->pad)
		return -EINVAL;

	nelem = in_trans->queue_size;
	size = (get_dbc_req_elem_size() + get_dbc_rsp_elem_size()) * nelem;
	if (size / nelem != get_dbc_req_elem_size() + get_dbc_rsp_elem_size())
		return -EINVAL;

	if (size + QAIC_DBC_Q_GAP + QAIC_DBC_Q_BUF_ALIGN < size)
		return -EINVAL;

	size = ALIGN((size + QAIC_DBC_Q_GAP), QAIC_DBC_Q_BUF_ALIGN);

	buf = dma_alloc_coherent(&qdev->pdev->dev, size, &dma_addr, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	trans_wrapper = add_wrapper(wrappers,
				    offsetof(struct wrapper_msg, trans) + sizeof(*out_trans));
	if (!trans_wrapper) {
		ret = -ENOMEM;
		goto free_dma;
	}
	trans_wrapper->len = sizeof(*out_trans);
	out_trans = (struct wire_trans_activate_to_dev *)&trans_wrapper->trans;

	out_trans->hdr.type = cpu_to_le32(QAIC_TRANS_ACTIVATE_TO_DEV);
	out_trans->hdr.len = cpu_to_le32(sizeof(*out_trans));
	out_trans->buf_len = cpu_to_le32(size);
	out_trans->req_q_addr = cpu_to_le64(dma_addr);
	out_trans->req_q_size = cpu_to_le32(nelem);
	out_trans->rsp_q_addr = cpu_to_le64(dma_addr + size - nelem * get_dbc_rsp_elem_size());
	out_trans->rsp_q_size = cpu_to_le32(nelem);
	out_trans->options = cpu_to_le32(in_trans->options);

	*user_len += in_trans->hdr.len;
	msg->hdr.len = cpu_to_le32(msg_hdr_len + sizeof(*out_trans));
	msg->hdr.count = incr_le32(msg->hdr.count);

	resources->buf = buf;
	resources->dma_addr = dma_addr;
	resources->total_size = size;
	resources->nelem = nelem;
	resources->rsp_q_base = buf + size - nelem * get_dbc_rsp_elem_size();
	return 0;

free_dma:
	dma_free_coherent(&qdev->pdev->dev, size, buf, dma_addr);
	return ret;
}

static int encode_deactivate(struct qaic_device *qdev, void *trans,
			     u32 *user_len, struct qaic_user *usr)
{
	struct qaic_manage_trans_deactivate *in_trans = trans;

	if (in_trans->dbc_id >= qdev->num_dbc || in_trans->pad)
		return -EINVAL;

	*user_len += in_trans->hdr.len;

	return disable_dbc(qdev, in_trans->dbc_id, usr);
}

static int encode_status(struct qaic_device *qdev, void *trans, struct wrapper_list *wrappers,
			 u32 *user_len)
{
	struct qaic_manage_trans_status_to_dev *in_trans = trans;
	struct wire_trans_status_to_dev *out_trans;
	struct wrapper_msg *trans_wrapper;
	struct wrapper_msg *wrapper;
	struct wire_msg *msg;
	u32 msg_hdr_len;

	wrapper = list_first_entry(&wrappers->list, struct wrapper_msg, list);
	msg = &wrapper->msg;
	msg_hdr_len = le32_to_cpu(msg->hdr.len);

	if (msg_hdr_len + in_trans->hdr.len > QAIC_MANAGE_MAX_MSG_LENGTH)
		return -ENOSPC;

	trans_wrapper = add_wrapper(wrappers, sizeof(*trans_wrapper));
	if (!trans_wrapper)
		return -ENOMEM;

	trans_wrapper->len = sizeof(*out_trans);
	out_trans = (struct wire_trans_status_to_dev *)&trans_wrapper->trans;

	out_trans->hdr.type = cpu_to_le32(QAIC_TRANS_STATUS_TO_DEV);
	out_trans->hdr.len = cpu_to_le32(in_trans->hdr.len);
	msg->hdr.len = cpu_to_le32(msg_hdr_len + in_trans->hdr.len);
	msg->hdr.count = incr_le32(msg->hdr.count);
	*user_len += in_trans->hdr.len;

	return 0;
}

static int encode_message(struct qaic_device *qdev, struct manage_msg *user_msg,
			  struct wrapper_list *wrappers, struct ioctl_resources *resources,
			  struct qaic_user *usr)
{
	struct qaic_manage_trans_hdr *trans_hdr;
	struct wrapper_msg *wrapper;
	struct wire_msg *msg;
	u32 user_len = 0;
	int ret;
	int i;

	if (!user_msg->count) {
		ret = -EINVAL;
		goto out;
	}

	wrapper = list_first_entry(&wrappers->list, struct wrapper_msg, list);
	msg = &wrapper->msg;

	msg->hdr.len = cpu_to_le32(sizeof(msg->hdr));

	if (resources->dma_chunk_id) {
		ret = encode_dma(qdev, resources->trans_hdr, wrappers, &user_len, resources, usr);
		msg->hdr.count = cpu_to_le32(1);
		goto out;
	}

	for (i = 0; i < user_msg->count; ++i) {
		if (user_len >= user_msg->len) {
			ret = -EINVAL;
			break;
		}
		trans_hdr = (struct qaic_manage_trans_hdr *)(user_msg->data + user_len);
		if (user_len + trans_hdr->len > user_msg->len) {
			ret = -EINVAL;
			break;
		}

		switch (trans_hdr->type) {
		case QAIC_TRANS_PASSTHROUGH_FROM_USR:
			ret = encode_passthrough(qdev, trans_hdr, wrappers, &user_len);
			break;
		case QAIC_TRANS_DMA_XFER_FROM_USR:
			ret = encode_dma(qdev, trans_hdr, wrappers, &user_len, resources, usr);
			break;
		case QAIC_TRANS_ACTIVATE_FROM_USR:
			ret = encode_activate(qdev, trans_hdr, wrappers, &user_len, resources);
			break;
		case QAIC_TRANS_DEACTIVATE_FROM_USR:
			ret = encode_deactivate(qdev, trans_hdr, &user_len, usr);
			break;
		case QAIC_TRANS_STATUS_FROM_USR:
			ret = encode_status(qdev, trans_hdr, wrappers, &user_len);
			break;
		default:
			ret = -EINVAL;
			break;
		}

		if (ret)
			break;
	}

	if (user_len != user_msg->len)
		ret = -EINVAL;
out:
	if (ret) {
		free_dma_xfers(qdev, resources);
		free_dbc_buf(qdev, resources);
		return ret;
	}

	return 0;
}

static int decode_passthrough(struct qaic_device *qdev, void *trans, struct manage_msg *user_msg,
			      u32 *msg_len)
{
	struct qaic_manage_trans_passthrough *out_trans;
	struct wire_trans_passthrough *in_trans = trans;
	u32 len;

	out_trans = (void *)user_msg->data + user_msg->len;

	len = le32_to_cpu(in_trans->hdr.len);
	if (len % 8 != 0)
		return -EINVAL;

	if (user_msg->len + len > QAIC_MANAGE_MAX_MSG_LENGTH)
		return -ENOSPC;

	memcpy(out_trans->data, in_trans->data, len - sizeof(in_trans->hdr));
	user_msg->len += len;
	*msg_len += len;
	out_trans->hdr.type = le32_to_cpu(in_trans->hdr.type);
	out_trans->hdr.len = len;

	return 0;
}

static int decode_activate(struct qaic_device *qdev, void *trans, struct manage_msg *user_msg,
			   u32 *msg_len, struct ioctl_resources *resources, struct qaic_user *usr)
{
	struct qaic_manage_trans_activate_from_dev *out_trans;
	struct wire_trans_activate_from_dev *in_trans = trans;
	u32 len;

	out_trans = (void *)user_msg->data + user_msg->len;

	len = le32_to_cpu(in_trans->hdr.len);
	if (user_msg->len + len > QAIC_MANAGE_MAX_MSG_LENGTH)
		return -ENOSPC;

	user_msg->len += len;
	*msg_len += len;
	out_trans->hdr.type = le32_to_cpu(in_trans->hdr.type);
	out_trans->hdr.len = len;
	out_trans->status = le32_to_cpu(in_trans->status);
	out_trans->dbc_id = le32_to_cpu(in_trans->dbc_id);
	out_trans->options = le64_to_cpu(in_trans->options);

	if (!resources->buf)
		/* how did we get an activate response without a request? */
		return -EINVAL;

	if (out_trans->dbc_id >= qdev->num_dbc)
		/*
		 * The device assigned an invalid resource, which should never
		 * happen. Return an error so the user can try to recover.
		 */
		return -ENODEV;

	if (out_trans->status)
		/*
		 * Allocating resources failed on device side. This is not an
		 * expected behaviour, user is expected to handle this situation.
		 */
		return -ECANCELED;

	resources->status = out_trans->status;
	resources->dbc_id = out_trans->dbc_id;
	save_dbc_buf(qdev, resources, usr);

	return 0;
}

static int decode_deactivate(struct qaic_device *qdev, void *trans, u32 *msg_len,
			     struct qaic_user *usr)
{
	struct wire_trans_deactivate_from_dev *in_trans = trans;
	u32 dbc_id = le32_to_cpu(in_trans->dbc_id);
	u32 status = le32_to_cpu(in_trans->status);

	if (dbc_id >= qdev->num_dbc)
		/*
		 * The device assigned an invalid resource, which should never
		 * happen. Inject an error so the user can try to recover.
		 */
		return -ENODEV;

	if (status) {
		/*
		 * Releasing resources failed on the device side, which puts
		 * us in a bind since they may still be in use, so enable the
		 * dbc. User is expected to retry deactivation.
		 */
		enable_dbc(qdev, dbc_id, usr);
		return -ECANCELED;
	}

	release_dbc(qdev, dbc_id);
	*msg_len += sizeof(*in_trans);

	return 0;
}

static int decode_status(struct qaic_device *qdev, void *trans, struct manage_msg *user_msg,
			 u32 *user_len, struct wire_msg *msg)
{
	struct qaic_manage_trans_status_from_dev *out_trans;
	struct wire_trans_status_from_dev *in_trans = trans;
	u32 len;

	out_trans = (void *)user_msg->data + user_msg->len;

	len = le32_to_cpu(in_trans->hdr.len);
	if (user_msg->len + len > QAIC_MANAGE_MAX_MSG_LENGTH)
		return -ENOSPC;

	out_trans->hdr.type = QAIC_TRANS_STATUS_FROM_DEV;
	out_trans->hdr.len = len;
	out_trans->major = le16_to_cpu(in_trans->major);
	out_trans->minor = le16_to_cpu(in_trans->minor);
	out_trans->status_flags = le64_to_cpu(in_trans->status_flags);
	out_trans->status = le32_to_cpu(in_trans->status);
	*user_len += le32_to_cpu(in_trans->hdr.len);
	user_msg->len += len;

	if (out_trans->status)
		return -ECANCELED;
	if (out_trans->status_flags & BIT(0) && !valid_crc(msg))
		return -EPIPE;

	return 0;
}

static int decode_message(struct qaic_device *qdev, struct manage_msg *user_msg,
			  struct wire_msg *msg, struct ioctl_resources *resources,
			  struct qaic_user *usr)
{
	u32 msg_hdr_len = le32_to_cpu(msg->hdr.len);
	struct wire_trans_hdr *trans_hdr;
	u32 msg_len = 0;
	int ret;
	int i;

	if (msg_hdr_len > QAIC_MANAGE_MAX_MSG_LENGTH)
		return -EINVAL;

	user_msg->len = 0;
	user_msg->count = le32_to_cpu(msg->hdr.count);

	for (i = 0; i < user_msg->count; ++i) {
		trans_hdr = (struct wire_trans_hdr *)(msg->data + msg_len);
		if (msg_len + le32_to_cpu(trans_hdr->len) > msg_hdr_len)
			return -EINVAL;

		switch (le32_to_cpu(trans_hdr->type)) {
		case QAIC_TRANS_PASSTHROUGH_FROM_DEV:
			ret = decode_passthrough(qdev, trans_hdr, user_msg, &msg_len);
			break;
		case QAIC_TRANS_ACTIVATE_FROM_DEV:
			ret = decode_activate(qdev, trans_hdr, user_msg, &msg_len, resources, usr);
			break;
		case QAIC_TRANS_DEACTIVATE_FROM_DEV:
			ret = decode_deactivate(qdev, trans_hdr, &msg_len, usr);
			break;
		case QAIC_TRANS_STATUS_FROM_DEV:
			ret = decode_status(qdev, trans_hdr, user_msg, &msg_len, msg);
			break;
		default:
			return -EINVAL;
		}

		if (ret)
			return ret;
	}

	if (msg_len != (msg_hdr_len - sizeof(msg->hdr)))
		return -EINVAL;

	return 0;
}

static void *msg_xfer(struct qaic_device *qdev, struct wrapper_list *wrappers, u32 seq_num,
		      bool ignore_signal)
{
	struct xfer_queue_elem elem;
	struct wire_msg *out_buf;
	struct wrapper_msg *w;
	int retry_count;
	long ret;

	if (qdev->in_reset) {
		mutex_unlock(&qdev->cntl_mutex);
		return ERR_PTR(-ENODEV);
	}

	elem.seq_num = seq_num;
	elem.buf = NULL;
	init_completion(&elem.xfer_done);
	if (likely(!qdev->cntl_lost_buf)) {
		/*
		 * The max size of request to device is QAIC_MANAGE_EXT_MSG_LENGTH.
		 * The max size of response from device is QAIC_MANAGE_MAX_MSG_LENGTH.
		 */
		out_buf = kmalloc(QAIC_MANAGE_MAX_MSG_LENGTH, GFP_KERNEL);
		if (!out_buf) {
			mutex_unlock(&qdev->cntl_mutex);
			return ERR_PTR(-ENOMEM);
		}

		ret = mhi_queue_buf(qdev->cntl_ch, DMA_FROM_DEVICE, out_buf,
				    QAIC_MANAGE_MAX_MSG_LENGTH, MHI_EOT);
		if (ret) {
			mutex_unlock(&qdev->cntl_mutex);
			return ERR_PTR(ret);
		}
	} else {
		/*
		 * we lost a buffer because we queued a recv buf, but then
		 * queuing the corresponding tx buf failed. To try to avoid
		 * a memory leak, lets reclaim it and use it for this
		 * transaction.
		 */
		qdev->cntl_lost_buf = false;
	}

	list_for_each_entry(w, &wrappers->list, list) {
		kref_get(&w->ref_count);
		retry_count = 0;
retry:
		ret = mhi_queue_buf(qdev->cntl_ch, DMA_TO_DEVICE, &w->msg, w->len,
				    list_is_last(&w->list, &wrappers->list) ? MHI_EOT : MHI_CHAIN);
		if (ret) {
			if (ret == -EAGAIN && retry_count++ < QAIC_MHI_RETRY_MAX) {
				msleep_interruptible(QAIC_MHI_RETRY_WAIT_MS);
				if (!signal_pending(current))
					goto retry;
			}

			qdev->cntl_lost_buf = true;
			kref_put(&w->ref_count, free_wrapper);
			mutex_unlock(&qdev->cntl_mutex);
			return ERR_PTR(ret);
		}
	}

	list_add_tail(&elem.list, &qdev->cntl_xfer_list);
	mutex_unlock(&qdev->cntl_mutex);

	if (ignore_signal)
		ret = wait_for_completion_timeout(&elem.xfer_done, control_resp_timeout_s * HZ);
	else
		ret = wait_for_completion_interruptible_timeout(&elem.xfer_done,
								control_resp_timeout_s * HZ);
	/*
	 * not using _interruptable because we have to cleanup or we'll
	 * likely cause memory corruption
	 */
	mutex_lock(&qdev->cntl_mutex);
	if (!list_empty(&elem.list))
		list_del(&elem.list);
	if (!ret && !elem.buf)
		ret = -ETIMEDOUT;
	else if (ret > 0 && !elem.buf)
		ret = -EIO;
	mutex_unlock(&qdev->cntl_mutex);

	if (ret < 0) {
		kfree(elem.buf);
		return ERR_PTR(ret);
	} else if (!qdev->valid_crc(elem.buf)) {
		kfree(elem.buf);
		return ERR_PTR(-EPIPE);
	}

	return elem.buf;
}

/* Add a transaction to abort the outstanding DMA continuation */
static int abort_dma_cont(struct qaic_device *qdev, struct wrapper_list *wrappers, u32 dma_chunk_id)
{
	struct wire_trans_dma_xfer *out_trans;
	u32 size = sizeof(*out_trans);
	struct wrapper_msg *wrapper;
	struct wrapper_msg *w;
	struct wire_msg *msg;

	wrapper = list_first_entry(&wrappers->list, struct wrapper_msg, list);
	msg = &wrapper->msg;

	/* Remove all but the first wrapper which has the msg header */
	list_for_each_entry_safe(wrapper, w, &wrappers->list, list)
		if (!list_is_first(&wrapper->list, &wrappers->list))
			kref_put(&wrapper->ref_count, free_wrapper);

	wrapper = add_wrapper(wrappers, offsetof(struct wrapper_msg, trans) + sizeof(*out_trans));

	if (!wrapper)
		return -ENOMEM;

	out_trans = (struct wire_trans_dma_xfer *)&wrapper->trans;
	out_trans->hdr.type = cpu_to_le32(QAIC_TRANS_DMA_XFER_TO_DEV);
	out_trans->hdr.len = cpu_to_le32(size);
	out_trans->tag = cpu_to_le32(0);
	out_trans->count = cpu_to_le32(0);
	out_trans->dma_chunk_id = cpu_to_le32(dma_chunk_id);

	msg->hdr.len = cpu_to_le32(size + sizeof(*msg));
	msg->hdr.count = cpu_to_le32(1);
	wrapper->len = size;

	return 0;
}

static struct wrapper_list *alloc_wrapper_list(void)
{
	struct wrapper_list *wrappers;

	wrappers = kmalloc(sizeof(*wrappers), GFP_KERNEL);
	if (!wrappers)
		return NULL;
	INIT_LIST_HEAD(&wrappers->list);
	spin_lock_init(&wrappers->lock);

	return wrappers;
}

static int qaic_manage_msg_xfer(struct qaic_device *qdev, struct qaic_user *usr,
				struct manage_msg *user_msg, struct ioctl_resources *resources,
				struct wire_msg **rsp)
{
	struct wrapper_list *wrappers;
	struct wrapper_msg *wrapper;
	struct wrapper_msg *w;
	bool all_done = false;
	struct wire_msg *msg;
	int ret;

	wrappers = alloc_wrapper_list();
	if (!wrappers)
		return -ENOMEM;

	wrapper = add_wrapper(wrappers, sizeof(*wrapper));
	if (!wrapper) {
		kfree(wrappers);
		return -ENOMEM;
	}

	msg = &wrapper->msg;
	wrapper->len = sizeof(*msg);

	ret = encode_message(qdev, user_msg, wrappers, resources, usr);
	if (ret && resources->dma_chunk_id)
		ret = abort_dma_cont(qdev, wrappers, resources->dma_chunk_id);
	if (ret)
		goto encode_failed;

	ret = mutex_lock_interruptible(&qdev->cntl_mutex);
	if (ret)
		goto lock_failed;

	msg->hdr.magic_number = MANAGE_MAGIC_NUMBER;
	msg->hdr.sequence_number = cpu_to_le32(qdev->next_seq_num++);

	if (usr) {
		msg->hdr.handle = cpu_to_le32(usr->handle);
		msg->hdr.partition_id = cpu_to_le32(usr->qddev->partition_id);
	} else {
		msg->hdr.handle = 0;
		msg->hdr.partition_id = cpu_to_le32(QAIC_NO_PARTITION);
	}

	msg->hdr.padding = cpu_to_le32(0);
	msg->hdr.crc32 = cpu_to_le32(qdev->gen_crc(wrappers));

	/* msg_xfer releases the mutex */
	*rsp = msg_xfer(qdev, wrappers, qdev->next_seq_num - 1, false);
	if (IS_ERR(*rsp))
		ret = PTR_ERR(*rsp);

lock_failed:
	free_dma_xfers(qdev, resources);
encode_failed:
	spin_lock(&wrappers->lock);
	list_for_each_entry_safe(wrapper, w, &wrappers->list, list)
		kref_put(&wrapper->ref_count, free_wrapper);
	all_done = list_empty(&wrappers->list);
	spin_unlock(&wrappers->lock);
	if (all_done)
		kfree(wrappers);

	return ret;
}

static int qaic_manage(struct qaic_device *qdev, struct qaic_user *usr, struct manage_msg *user_msg)
{
	struct wire_trans_dma_xfer_cont *dma_cont = NULL;
	struct ioctl_resources resources;
	struct wire_msg *rsp = NULL;
	int ret;

	memset(&resources, 0, sizeof(struct ioctl_resources));

	INIT_LIST_HEAD(&resources.dma_xfers);

	if (user_msg->len > QAIC_MANAGE_MAX_MSG_LENGTH ||
	    user_msg->count > QAIC_MANAGE_MAX_MSG_LENGTH / sizeof(struct qaic_manage_trans_hdr))
		return -EINVAL;

dma_xfer_continue:
	ret = qaic_manage_msg_xfer(qdev, usr, user_msg, &resources, &rsp);
	if (ret)
		return ret;
	/* dma_cont should be the only transaction if present */
	if (le32_to_cpu(rsp->hdr.count) == 1) {
		dma_cont = (struct wire_trans_dma_xfer_cont *)rsp->data;
		if (le32_to_cpu(dma_cont->hdr.type) != QAIC_TRANS_DMA_XFER_CONT)
			dma_cont = NULL;
	}
	if (dma_cont) {
		if (le32_to_cpu(dma_cont->dma_chunk_id) == resources.dma_chunk_id &&
		    le64_to_cpu(dma_cont->xferred_size) == resources.xferred_dma_size) {
			kfree(rsp);
			goto dma_xfer_continue;
		}

		ret = -EINVAL;
		goto dma_cont_failed;
	}

	ret = decode_message(qdev, user_msg, rsp, &resources, usr);

dma_cont_failed:
	free_dbc_buf(qdev, &resources);
	kfree(rsp);
	return ret;
}

int qaic_manage_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv)
{
	struct qaic_manage_msg *user_msg;
	struct qaic_device *qdev;
	struct manage_msg *msg;
	struct qaic_user *usr;
	u8 __user *user_data;
	int qdev_rcu_id;
	int usr_rcu_id;
	int ret;

	usr = file_priv->driver_priv;

	usr_rcu_id = srcu_read_lock(&usr->qddev_lock);
	if (!usr->qddev) {
		srcu_read_unlock(&usr->qddev_lock, usr_rcu_id);
		return -ENODEV;
	}

	qdev = usr->qddev->qdev;

	qdev_rcu_id = srcu_read_lock(&qdev->dev_lock);
	if (qdev->in_reset) {
		srcu_read_unlock(&qdev->dev_lock, qdev_rcu_id);
		srcu_read_unlock(&usr->qddev_lock, usr_rcu_id);
		return -ENODEV;
	}

	user_msg = data;

	if (user_msg->len > QAIC_MANAGE_MAX_MSG_LENGTH) {
		ret = -EINVAL;
		goto out;
	}

	msg = kzalloc(QAIC_MANAGE_MAX_MSG_LENGTH + sizeof(*msg), GFP_KERNEL);
	if (!msg) {
		ret = -ENOMEM;
		goto out;
	}

	msg->len = user_msg->len;
	msg->count = user_msg->count;

	user_data = u64_to_user_ptr(user_msg->data);

	if (copy_from_user(msg->data, user_data, user_msg->len)) {
		ret = -EFAULT;
		goto free_msg;
	}

	ret = qaic_manage(qdev, usr, msg);

	/*
	 * If the qaic_manage() is successful then we copy the message onto
	 * userspace memory but we have an exception for -ECANCELED.
	 * For -ECANCELED, it means that device has NACKed the message with a
	 * status error code which userspace would like to know.
	 */
	if (ret == -ECANCELED || !ret) {
		if (copy_to_user(user_data, msg->data, msg->len)) {
			ret = -EFAULT;
		} else {
			user_msg->len = msg->len;
			user_msg->count = msg->count;
		}
	}

free_msg:
	kfree(msg);
out:
	srcu_read_unlock(&qdev->dev_lock, qdev_rcu_id);
	srcu_read_unlock(&usr->qddev_lock, usr_rcu_id);
	return ret;
}

int get_cntl_version(struct qaic_device *qdev, struct qaic_user *usr, u16 *major, u16 *minor)
{
	struct qaic_manage_trans_status_from_dev *status_result;
	struct qaic_manage_trans_status_to_dev *status_query;
	struct manage_msg *user_msg;
	int ret;

	user_msg = kmalloc(sizeof(*user_msg) + sizeof(*status_result), GFP_KERNEL);
	if (!user_msg) {
		ret = -ENOMEM;
		goto out;
	}
	user_msg->len = sizeof(*status_query);
	user_msg->count = 1;

	status_query = (struct qaic_manage_trans_status_to_dev *)user_msg->data;
	status_query->hdr.type = QAIC_TRANS_STATUS_FROM_USR;
	status_query->hdr.len = sizeof(status_query->hdr);

	ret = qaic_manage(qdev, usr, user_msg);
	if (ret)
		goto kfree_user_msg;
	status_result = (struct qaic_manage_trans_status_from_dev *)user_msg->data;
	*major = status_result->major;
	*minor = status_result->minor;

	if (status_result->status_flags & BIT(0)) { /* device is using CRC */
		/* By default qdev->gen_crc is programmed to generate CRC */
		qdev->valid_crc = valid_crc;
	} else {
		/* By default qdev->valid_crc is programmed to bypass CRC */
		qdev->gen_crc = gen_crc_stub;
	}

kfree_user_msg:
	kfree(user_msg);
out:
	return ret;
}

static void resp_worker(struct work_struct *work)
{
	struct resp_work *resp = container_of(work, struct resp_work, work);
	struct qaic_device *qdev = resp->qdev;
	struct wire_msg *msg = resp->buf;
	struct xfer_queue_elem *elem;
	struct xfer_queue_elem *i;
	bool found = false;

	mutex_lock(&qdev->cntl_mutex);
	list_for_each_entry_safe(elem, i, &qdev->cntl_xfer_list, list) {
		if (elem->seq_num == le32_to_cpu(msg->hdr.sequence_number)) {
			found = true;
			list_del_init(&elem->list);
			elem->buf = msg;
			complete_all(&elem->xfer_done);
			break;
		}
	}
	mutex_unlock(&qdev->cntl_mutex);

	if (!found)
		/* request must have timed out, drop packet */
		kfree(msg);

	kfree(resp);
}

static void free_wrapper_from_list(struct wrapper_list *wrappers, struct wrapper_msg *wrapper)
{
	bool all_done = false;

	spin_lock(&wrappers->lock);
	kref_put(&wrapper->ref_count, free_wrapper);
	all_done = list_empty(&wrappers->list);
	spin_unlock(&wrappers->lock);

	if (all_done)
		kfree(wrappers);
}

void qaic_mhi_ul_xfer_cb(struct mhi_device *mhi_dev, struct mhi_result *mhi_result)
{
	struct wire_msg *msg = mhi_result->buf_addr;
	struct wrapper_msg *wrapper = container_of(msg, struct wrapper_msg, msg);

	free_wrapper_from_list(wrapper->head, wrapper);
}

void qaic_mhi_dl_xfer_cb(struct mhi_device *mhi_dev, struct mhi_result *mhi_result)
{
	struct qaic_device *qdev = dev_get_drvdata(&mhi_dev->dev);
	struct wire_msg *msg = mhi_result->buf_addr;
	struct resp_work *resp;

	if (mhi_result->transaction_status || msg->hdr.magic_number != MANAGE_MAGIC_NUMBER) {
		kfree(msg);
		return;
	}

	resp = kmalloc(sizeof(*resp), GFP_ATOMIC);
	if (!resp) {
		kfree(msg);
		return;
	}

	INIT_WORK(&resp->work, resp_worker);
	resp->qdev = qdev;
	resp->buf = msg;
	queue_work(qdev->cntl_wq, &resp->work);
}

int qaic_control_open(struct qaic_device *qdev)
{
	if (!qdev->cntl_ch)
		return -ENODEV;

	qdev->cntl_lost_buf = false;
	/*
	 * By default qaic should assume that device has CRC enabled.
	 * Qaic comes to know if device has CRC enabled or disabled during the
	 * device status transaction, which is the first transaction performed
	 * on control channel.
	 *
	 * So CRC validation of first device status transaction response is
	 * ignored (by calling valid_crc_stub) and is done later during decoding
	 * if device has CRC enabled.
	 * Now that qaic knows whether device has CRC enabled or not it acts
	 * accordingly.
	 */
	qdev->gen_crc = gen_crc;
	qdev->valid_crc = valid_crc_stub;

	return mhi_prepare_for_transfer(qdev->cntl_ch);
}

void qaic_control_close(struct qaic_device *qdev)
{
	mhi_unprepare_from_transfer(qdev->cntl_ch);
}

void qaic_release_usr(struct qaic_device *qdev, struct qaic_user *usr)
{
	struct wire_trans_terminate_to_dev *trans;
	struct wrapper_list *wrappers;
	struct wrapper_msg *wrapper;
	struct wire_msg *msg;
	struct wire_msg *rsp;

	wrappers = alloc_wrapper_list();
	if (!wrappers)
		return;

	wrapper = add_wrapper(wrappers, sizeof(*wrapper) + sizeof(*msg) + sizeof(*trans));
	if (!wrapper)
		return;

	msg = &wrapper->msg;

	trans = (struct wire_trans_terminate_to_dev *)msg->data;

	trans->hdr.type = cpu_to_le32(QAIC_TRANS_TERMINATE_TO_DEV);
	trans->hdr.len = cpu_to_le32(sizeof(*trans));
	trans->handle = cpu_to_le32(usr->handle);

	mutex_lock(&qdev->cntl_mutex);
	wrapper->len = sizeof(msg->hdr) + sizeof(*trans);
	msg->hdr.magic_number = MANAGE_MAGIC_NUMBER;
	msg->hdr.sequence_number = cpu_to_le32(qdev->next_seq_num++);
	msg->hdr.len = cpu_to_le32(wrapper->len);
	msg->hdr.count = cpu_to_le32(1);
	msg->hdr.handle = cpu_to_le32(usr->handle);
	msg->hdr.padding = cpu_to_le32(0);
	msg->hdr.crc32 = cpu_to_le32(qdev->gen_crc(wrappers));

	/*
	 * msg_xfer releases the mutex
	 * We don't care about the return of msg_xfer since we will not do
	 * anything different based on what happens.
	 * We ignore pending signals since one will be set if the user is
	 * killed, and we need give the device a chance to cleanup, otherwise
	 * DMA may still be in progress when we return.
	 */
	rsp = msg_xfer(qdev, wrappers, qdev->next_seq_num - 1, true);
	if (!IS_ERR(rsp))
		kfree(rsp);
	free_wrapper_from_list(wrappers, wrapper);
}

void wake_all_cntl(struct qaic_device *qdev)
{
	struct xfer_queue_elem *elem;
	struct xfer_queue_elem *i;

	mutex_lock(&qdev->cntl_mutex);
	list_for_each_entry_safe(elem, i, &qdev->cntl_xfer_list, list) {
		list_del_init(&elem->list);
		complete_all(&elem->xfer_done);
	}
	mutex_unlock(&qdev->cntl_mutex);
}