static int parse_xfer_event()

in mhi/core/main.c [558:691]

• 99 lines of code
• 21 McCabe index (conditional complexity)

static int parse_xfer_event(struct mhi_controller *mhi_cntrl,
			    struct mhi_tre *event,
			    struct mhi_chan *mhi_chan)
{
	struct mhi_ring *buf_ring, *tre_ring;
	struct device *dev = &mhi_cntrl->mhi_dev->dev;
	struct mhi_result result;
	unsigned long flags = 0;
	u32 ev_code;

	ev_code = MHI_TRE_GET_EV_CODE(event);
	buf_ring = &mhi_chan->buf_ring;
	tre_ring = &mhi_chan->tre_ring;

	result.transaction_status = (ev_code == MHI_EV_CC_OVERFLOW) ?
		-EOVERFLOW : 0;

	/*
	 * If it's a DB Event then we need to grab the lock
	 * with preemption disabled and as a write because we
	 * have to update db register and there are chances that
	 * another thread could be doing the same.
	 */
	if (ev_code >= MHI_EV_CC_OOB)
		write_lock_irqsave(&mhi_chan->lock, flags);
	else
		read_lock_bh(&mhi_chan->lock);

	if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED)
		goto end_process_tx_event;

	switch (ev_code) {
	case MHI_EV_CC_OVERFLOW:
	case MHI_EV_CC_EOB:
	case MHI_EV_CC_EOT:
	{
		dma_addr_t ptr = MHI_TRE_GET_EV_PTR(event);
		struct mhi_tre *local_rp, *ev_tre;
		void *dev_rp;
		struct mhi_buf_info *buf_info;
		u16 xfer_len;

		if (!is_valid_ring_ptr(tre_ring, ptr)) {
			dev_err(&mhi_cntrl->mhi_dev->dev,
				"Event element points outside of the tre ring\n");
			break;
		}
		/* Get the TRB this event points to */
		ev_tre = mhi_to_virtual(tre_ring, ptr);

		dev_rp = ev_tre + 1;
		if (dev_rp >= (tre_ring->base + tre_ring->len))
			dev_rp = tre_ring->base;

		result.dir = mhi_chan->dir;

		local_rp = tre_ring->rp;
		while (local_rp != dev_rp) {
			buf_info = buf_ring->rp;
			/* If it's the last TRE, get length from the event */
			if (local_rp == ev_tre)
				xfer_len = MHI_TRE_GET_EV_LEN(event);
			else
				xfer_len = buf_info->len;

			/* Unmap if it's not pre-mapped by client */
			if (likely(!buf_info->pre_mapped))
				mhi_cntrl->unmap_single(mhi_cntrl, buf_info);

			result.buf_addr = buf_info->cb_buf;

			/* truncate to buf len if xfer_len is larger */
			result.bytes_xferd =
				min_t(u16, xfer_len, buf_info->len);
			mhi_del_ring_element(mhi_cntrl, buf_ring);
			mhi_del_ring_element(mhi_cntrl, tre_ring);
			local_rp = tre_ring->rp;

			/* notify client */
			mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);

			if (mhi_chan->dir == DMA_TO_DEVICE) {
				atomic_dec(&mhi_cntrl->pending_pkts);
				/* Release the reference got from mhi_queue() */
				mhi_cntrl->runtime_put(mhi_cntrl);
			}

			/*
			 * Recycle the buffer if buffer is pre-allocated,
			 * if there is an error, not much we can do apart
			 * from dropping the packet
			 */
			if (mhi_chan->pre_alloc) {
				if (mhi_queue_buf(mhi_chan->mhi_dev,
						  mhi_chan->dir,
						  buf_info->cb_buf,
						  buf_info->len, MHI_EOT)) {
					dev_err(dev,
						"Error recycling buffer for chan:%d\n",
						mhi_chan->chan);
					kfree(buf_info->cb_buf);
				}
			}
		}
		break;
	} /* CC_EOT */
	case MHI_EV_CC_OOB:
	case MHI_EV_CC_DB_MODE:
	{
		unsigned long pm_lock_flags;

		mhi_chan->db_cfg.db_mode = 1;
		read_lock_irqsave(&mhi_cntrl->pm_lock, pm_lock_flags);
		if (tre_ring->wp != tre_ring->rp &&
		    MHI_DB_ACCESS_VALID(mhi_cntrl)) {
			mhi_ring_chan_db(mhi_cntrl, mhi_chan);
		}
		read_unlock_irqrestore(&mhi_cntrl->pm_lock, pm_lock_flags);
		break;
	}
	case MHI_EV_CC_BAD_TRE:
	default:
		dev_err(dev, "Unknown event 0x%x\n", ev_code);
		break;
	} /* switch(MHI_EV_READ_CODE(EV_TRB_CODE,event)) */

end_process_tx_event:
	if (ev_code >= MHI_EV_CC_OOB)
		write_unlock_irqrestore(&mhi_chan->lock, flags);
	else
		read_unlock_bh(&mhi_chan->lock);

	return 0;
}