// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   *  BSG helper library
   *
   *  Copyright (C) 2008   James Smart, Emulex Corporation
   *  Copyright (C) 2011   Red Hat, Inc.  All rights reserved.
   *  Copyright (C) 2011   Mike Christie

   */

  #include <linux/bsg.h>

  #include <linux/slab.h>

  #include <linux/blk-mq.h>

  #include <linux/delay.h>
  #include <linux/scatterlist.h>
  #include <linux/bsg-lib.h>

  #include <linux/export.h>

  #include <scsi/scsi_cmnd.h>

  #include <scsi/sg.h>
  
  #define uptr64(val) ((void __user *)(uintptr_t)(val))

  struct bsg_set {
  	struct blk_mq_tag_set	tag_set;

  	struct bsg_device	*bd;

  	bsg_job_fn		*job_fn;
  	bsg_timeout_fn		*timeout_fn;
  };

  static int bsg_transport_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
  		fmode_t mode, unsigned int timeout)

  {

  	struct bsg_job *job;
  	struct request *rq;
  	struct bio *bio;
  	int ret;

  	if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
  	    hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_TRANSPORT)
  		return -EINVAL;
  	if (!capable(CAP_SYS_RAWIO))
  		return -EPERM;

  	rq = blk_get_request(q, hdr->dout_xfer_len ?
  			     REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
  	if (IS_ERR(rq))
  		return PTR_ERR(rq);
  	rq->timeout = timeout;

  	job = blk_mq_rq_to_pdu(rq);

  	job->request_len = hdr->request_len;
  	job->request = memdup_user(uptr64(hdr->request), hdr->request_len);

  	if (IS_ERR(job->request)) {
  		ret = PTR_ERR(job->request);
  		goto out_put_request;
  	}

  
  	if (hdr->dout_xfer_len && hdr->din_xfer_len) {

  		job->bidi_rq = blk_get_request(rq->q, REQ_OP_DRV_IN, 0);

  		if (IS_ERR(job->bidi_rq)) {
  			ret = PTR_ERR(job->bidi_rq);

  			goto out_free_job_request;

  		}
  
  		ret = blk_rq_map_user(rq->q, job->bidi_rq, NULL,
  				uptr64(hdr->din_xferp), hdr->din_xfer_len,
  				GFP_KERNEL);
  		if (ret)
  			goto out_free_bidi_rq;
  
  		job->bidi_bio = job->bidi_rq->bio;
  	} else {
  		job->bidi_rq = NULL;
  		job->bidi_bio = NULL;
  	}

  	ret = 0;

  	if (hdr->dout_xfer_len) {
  		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->dout_xferp),
  				hdr->dout_xfer_len, GFP_KERNEL);
  	} else if (hdr->din_xfer_len) {
  		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->din_xferp),
  				hdr->din_xfer_len, GFP_KERNEL);
  	}

  	if (ret)
  		goto out_unmap_bidi_rq;

  	bio = rq->bio;
  	blk_execute_rq(NULL, rq, !(hdr->flags & BSG_FLAG_Q_AT_TAIL));

  
  	/*
  	 * The assignments below don't make much sense, but are kept for
  	 * bug by bug backwards compatibility:
  	 */
  	hdr->device_status = job->result & 0xff;
  	hdr->transport_status = host_byte(job->result);

  	hdr->driver_status = 0;

  	hdr->info = 0;
  	if (hdr->device_status || hdr->transport_status || hdr->driver_status)
  		hdr->info |= SG_INFO_CHECK;
  	hdr->response_len = 0;
  
  	if (job->result < 0) {
  		/* we're only returning the result field in the reply */
  		job->reply_len = sizeof(u32);
  		ret = job->result;
  	}
  
  	if (job->reply_len && hdr->response) {
  		int len = min(hdr->max_response_len, job->reply_len);
  
  		if (copy_to_user(uptr64(hdr->response), job->reply, len))
  			ret = -EFAULT;
  		else
  			hdr->response_len = len;
  	}
  
  	/* we assume all request payload was transferred, residual == 0 */
  	hdr->dout_resid = 0;

  	if (job->bidi_rq) {

  		unsigned int rsp_len = job->reply_payload.payload_len;
  
  		if (WARN_ON(job->reply_payload_rcv_len > rsp_len))
  			hdr->din_resid = 0;
  		else
  			hdr->din_resid = rsp_len - job->reply_payload_rcv_len;
  	} else {
  		hdr->din_resid = 0;
  	}

  	blk_rq_unmap_user(bio);
  out_unmap_bidi_rq:
  	if (job->bidi_rq)

  		blk_rq_unmap_user(job->bidi_bio);

  out_free_bidi_rq:
  	if (job->bidi_rq)

  		blk_put_request(job->bidi_rq);

  out_free_job_request:

  	kfree(job->request);

  out_put_request:
  	blk_put_request(rq);
  	return ret;

  }

  /**

   * bsg_teardown_job - routine to teardown a bsg job

   * @kref: kref inside bsg_job that is to be torn down

   */

  static void bsg_teardown_job(struct kref *kref)

  {

  	struct bsg_job *job = container_of(kref, struct bsg_job, kref);

  	struct request *rq = blk_mq_rq_from_pdu(job);

  	put_device(job->dev);	/* release reference for the request */
  
  	kfree(job->request_payload.sg_list);
  	kfree(job->reply_payload.sg_list);

  	blk_mq_end_request(rq, BLK_STS_OK);

  }

  void bsg_job_put(struct bsg_job *job)
  {

  	kref_put(&job->kref, bsg_teardown_job);

  }
  EXPORT_SYMBOL_GPL(bsg_job_put);
  
  int bsg_job_get(struct bsg_job *job)
  {
  	return kref_get_unless_zero(&job->kref);
  }
  EXPORT_SYMBOL_GPL(bsg_job_get);

  
  /**
   * bsg_job_done - completion routine for bsg requests
   * @job: bsg_job that is complete
   * @result: job reply result
   * @reply_payload_rcv_len: length of payload recvd
   *
   * The LLD should call this when the bsg job has completed.
   */
  void bsg_job_done(struct bsg_job *job, int result,
  		  unsigned int reply_payload_rcv_len)
  {

  	struct request *rq = blk_mq_rq_from_pdu(job);

  	job->result = result;
  	job->reply_payload_rcv_len = reply_payload_rcv_len;

  	if (likely(!blk_should_fake_timeout(rq->q)))
  		blk_mq_complete_request(rq);

  }
  EXPORT_SYMBOL_GPL(bsg_job_done);
  
  /**

   * bsg_complete - softirq done routine for destroying the bsg requests

   * @rq: BSG request that holds the job to be destroyed
   */

  static void bsg_complete(struct request *rq)

  {

  	struct bsg_job *job = blk_mq_rq_to_pdu(rq);

  	bsg_job_put(job);

  }
  
  static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
  {
  	size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
  
  	BUG_ON(!req->nr_phys_segments);

  	buf->sg_list = kmalloc(sz, GFP_KERNEL);

  	if (!buf->sg_list)
  		return -ENOMEM;
  	sg_init_table(buf->sg_list, req->nr_phys_segments);
  	buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
  	buf->payload_len = blk_rq_bytes(req);
  	return 0;
  }
  
  /**

   * bsg_prepare_job - create the bsg_job structure for the bsg request

   * @dev: device that is being sent the bsg request
   * @req: BSG request that needs a job structure
   */

  static bool bsg_prepare_job(struct device *dev, struct request *req)

  {

  	struct bsg_job *job = blk_mq_rq_to_pdu(req);

  	int ret;

  	job->timeout = req->timeout;

  	if (req->bio) {
  		ret = bsg_map_buffer(&job->request_payload, req);
  		if (ret)
  			goto failjob_rls_job;
  	}

  	if (job->bidi_rq) {
  		ret = bsg_map_buffer(&job->reply_payload, job->bidi_rq);

  		if (ret)
  			goto failjob_rls_rqst_payload;
  	}
  	job->dev = dev;
  	/* take a reference for the request */
  	get_device(job->dev);

  	kref_init(&job->kref);

  	return true;

  
  failjob_rls_rqst_payload:
  	kfree(job->request_payload.sg_list);
  failjob_rls_job:

  	job->result = -ENOMEM;
  	return false;

  }

  /**

   * bsg_queue_rq - generic handler for bsg requests
   * @hctx: hardware queue
   * @bd: queue data

   *
   * On error the create_bsg_job function should return a -Exyz error value

   * that will be set to ->result.

   *
   * Drivers/subsys should pass this to the queue init function.
   */

  static blk_status_t bsg_queue_rq(struct blk_mq_hw_ctx *hctx,
  				 const struct blk_mq_queue_data *bd)

  {

  	struct request_queue *q = hctx->queue;

  	struct device *dev = q->queuedata;

  	struct request *req = bd->rq;

  	struct bsg_set *bset =
  		container_of(q->tag_set, struct bsg_set, tag_set);

  	blk_status_t sts = BLK_STS_IOERR;

  	int ret;

  	blk_mq_start_request(req);

  	if (!get_device(dev))

  		return BLK_STS_IOERR;
  
  	if (!bsg_prepare_job(dev, req))

  		goto out;

  	ret = bset->job_fn(blk_mq_rq_to_pdu(req));

  	if (!ret)
  		sts = BLK_STS_OK;

  out:

  	put_device(dev);

  	return sts;

  }

  /* called right after the request is allocated for the request_queue */

  static int bsg_init_rq(struct blk_mq_tag_set *set, struct request *req,
  		       unsigned int hctx_idx, unsigned int numa_node)

  {
  	struct bsg_job *job = blk_mq_rq_to_pdu(req);

  	job->reply = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);

  	if (!job->reply)

  		return -ENOMEM;

  	return 0;
  }

  /* called right before the request is given to the request_queue user */

  static void bsg_initialize_rq(struct request *req)
  {
  	struct bsg_job *job = blk_mq_rq_to_pdu(req);

  	void *reply = job->reply;

  	memset(job, 0, sizeof(*job));

  	job->reply = reply;
  	job->reply_len = SCSI_SENSE_BUFFERSIZE;

  	job->dd_data = job + 1;

  }

  static void bsg_exit_rq(struct blk_mq_tag_set *set, struct request *req,
  		       unsigned int hctx_idx)

  {
  	struct bsg_job *job = blk_mq_rq_to_pdu(req);

  	kfree(job->reply);

  }

  void bsg_remove_queue(struct request_queue *q)
  {
  	if (q) {

  		struct bsg_set *bset =
  			container_of(q->tag_set, struct bsg_set, tag_set);

  		bsg_unregister_queue(bset->bd);

  		blk_cleanup_queue(q);

  		blk_mq_free_tag_set(&bset->tag_set);
  		kfree(bset);

  	}
  }
  EXPORT_SYMBOL_GPL(bsg_remove_queue);

  static enum blk_eh_timer_return bsg_timeout(struct request *rq, bool reserved)
  {

  	struct bsg_set *bset =
  		container_of(rq->q->tag_set, struct bsg_set, tag_set);

  	if (!bset->timeout_fn)
  		return BLK_EH_DONE;
  	return bset->timeout_fn(rq);

  }
  
  static const struct blk_mq_ops bsg_mq_ops = {
  	.queue_rq		= bsg_queue_rq,
  	.init_request		= bsg_init_rq,
  	.exit_request		= bsg_exit_rq,
  	.initialize_rq_fn	= bsg_initialize_rq,
  	.complete		= bsg_complete,
  	.timeout		= bsg_timeout,
  };

  /**
   * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
   * @dev: device to attach bsg device to

   * @name: device to give bsg device
   * @job_fn: bsg job handler

   * @timeout: timeout handler function pointer

   * @dd_job_size: size of LLD data needed for each job

   */

  struct request_queue *bsg_setup_queue(struct device *dev, const char *name,

  		bsg_job_fn *job_fn, bsg_timeout_fn *timeout, int dd_job_size)

  {

  	struct bsg_set *bset;

  	struct blk_mq_tag_set *set;

  	struct request_queue *q;

  	int ret = -ENOMEM;

  	bset = kzalloc(sizeof(*bset), GFP_KERNEL);
  	if (!bset)

  		return ERR_PTR(-ENOMEM);

  	bset->job_fn = job_fn;
  	bset->timeout_fn = timeout;
  
  	set = &bset->tag_set;

  	set->ops = &bsg_mq_ops;

  	set->nr_hw_queues = 1;
  	set->queue_depth = 128;
  	set->numa_node = NUMA_NO_NODE;
  	set->cmd_size = sizeof(struct bsg_job) + dd_job_size;
  	set->flags = BLK_MQ_F_NO_SCHED | BLK_MQ_F_BLOCKING;
  	if (blk_mq_alloc_tag_set(set))
  		goto out_tag_set;
  
  	q = blk_mq_init_queue(set);
  	if (IS_ERR(q)) {
  		ret = PTR_ERR(q);
  		goto out_queue;
  	}

  	q->queuedata = dev;

  	blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);

  	bset->bd = bsg_register_queue(q, dev, name, bsg_transport_sg_io_fn);

  	if (IS_ERR(bset->bd)) {
  		ret = PTR_ERR(bset->bd);

  		goto out_cleanup_queue;

  	}

  	return q;

  out_cleanup_queue:
  	blk_cleanup_queue(q);

  out_queue:
  	blk_mq_free_tag_set(set);
  out_tag_set:

  	kfree(bset);

  	return ERR_PTR(ret);

  }
  EXPORT_SYMBOL_GPL(bsg_setup_queue);