static int trf7970a_send_cmd()

in trf7970a.c [1459:1561]

• 80 lines of code
• 14 McCabe index (conditional complexity)

static int trf7970a_send_cmd(struct nfc_digital_dev *ddev,
			     struct sk_buff *skb, u16 timeout,
			     nfc_digital_cmd_complete_t cb, void *arg)
{
	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
	u8 prefix[5];
	unsigned int len;
	int ret;
	u8 status;

	dev_dbg(trf->dev, "New request - state: %d, timeout: %d ms, len: %d\n",
		trf->state, timeout, skb->len);

	if (skb->len > TRF7970A_TX_MAX)
		return -EINVAL;

	mutex_lock(&trf->lock);

	if ((trf->state != TRF7970A_ST_IDLE) &&
	    (trf->state != TRF7970A_ST_IDLE_RX_BLOCKED)) {
		dev_err(trf->dev, "%s - Bogus state: %d\n", __func__,
			trf->state);
		ret = -EIO;
		goto out_err;
	}

	if (trf->aborting) {
		dev_dbg(trf->dev, "Abort process complete\n");
		trf->aborting = false;
		ret = -ECANCELED;
		goto out_err;
	}

	if (timeout) {
		trf->rx_skb = nfc_alloc_recv_skb(TRF7970A_RX_SKB_ALLOC_SIZE,
						 GFP_KERNEL);
		if (!trf->rx_skb) {
			dev_dbg(trf->dev, "Can't alloc rx_skb\n");
			ret = -ENOMEM;
			goto out_err;
		}
	}

	if (trf->state == TRF7970A_ST_IDLE_RX_BLOCKED) {
		ret = trf7970a_cmd(trf, TRF7970A_CMD_ENABLE_RX);
		if (ret)
			goto out_err;

		trf->state = TRF7970A_ST_IDLE;
	}

	if (trf->is_initiator) {
		ret = trf7970a_per_cmd_config(trf, skb);
		if (ret)
			goto out_err;
	}

	trf->ddev = ddev;
	trf->tx_skb = skb;
	trf->cb = cb;
	trf->cb_arg = arg;
	trf->timeout = timeout;
	trf->ignore_timeout = false;

	len = skb->len;

	/* TX data must be prefixed with a FIFO reset cmd, a cmd that depends
	 * on what the current framing is, the address of the TX length byte 1
	 * register (0x1d), and the 2 byte length of the data to be transmitted.
	 * That totals 5 bytes.
	 */
	prefix[0] = TRF7970A_CMD_BIT_CTRL |
	    TRF7970A_CMD_BIT_OPCODE(TRF7970A_CMD_FIFO_RESET);
	prefix[1] = TRF7970A_CMD_BIT_CTRL |
	    TRF7970A_CMD_BIT_OPCODE(trf->tx_cmd);
	prefix[2] = TRF7970A_CMD_BIT_CONTINUOUS | TRF7970A_TX_LENGTH_BYTE1;

	if (trf->framing == NFC_DIGITAL_FRAMING_NFCA_SHORT) {
		prefix[3] = 0x00;
		prefix[4] = 0x0f;	/* 7 bits */
	} else {
		prefix[3] = (len & 0xf00) >> 4;
		prefix[3] |= ((len & 0xf0) >> 4);
		prefix[4] = ((len & 0x0f) << 4);
	}

	len = min_t(int, skb->len, TRF7970A_FIFO_SIZE);

	/* Clear possible spurious interrupt */
	ret = trf7970a_read_irqstatus(trf, &status);
	if (ret)
		goto out_err;

	ret = trf7970a_transmit(trf, skb, len, prefix, sizeof(prefix));
	if (ret) {
		kfree_skb(trf->rx_skb);
		trf->rx_skb = NULL;
	}

out_err:
	mutex_unlock(&trf->lock);
	return ret;
}