static int trf7970a_per_cmd_config()

in trf7970a.c [1390:1457]

• 50 lines of code
• 16 McCabe index (conditional complexity)

static int trf7970a_per_cmd_config(struct trf7970a *trf,
				   const struct sk_buff *skb)
{
	const u8 *req = skb->data;
	u8 special_fcn_reg1, iso_ctrl;
	int ret;

	trf->issue_eof = false;

	/* When issuing Type 2 read command, make sure the '4_bit_RX' bit in
	 * special functions register 1 is cleared; otherwise, its a write or
	 * sector select command and '4_bit_RX' must be set.
	 *
	 * When issuing an ISO 15693 command, inspect the flags byte to see
	 * what speed to use.  Also, remember if the OPTION flag is set on
	 * a Type 5 write or lock command so the driver will know that it
	 * has to send an EOF in order to get a response.
	 */
	if ((trf->technology == NFC_DIGITAL_RF_TECH_106A) &&
	    (trf->framing == NFC_DIGITAL_FRAMING_NFCA_T2T)) {
		if (req[0] == NFC_T2T_CMD_READ)
			special_fcn_reg1 = 0;
		else
			special_fcn_reg1 = TRF7970A_SPECIAL_FCN_REG1_4_BIT_RX;

		if (special_fcn_reg1 != trf->special_fcn_reg1) {
			ret = trf7970a_write(trf, TRF7970A_SPECIAL_FCN_REG1,
					     special_fcn_reg1);
			if (ret)
				return ret;

			trf->special_fcn_reg1 = special_fcn_reg1;
		}
	} else if (trf->technology == NFC_DIGITAL_RF_TECH_ISO15693) {
		iso_ctrl = trf->iso_ctrl & ~TRF7970A_ISO_CTRL_RFID_SPEED_MASK;

		switch (req[0] & ISO15693_REQ_FLAG_SPEED_MASK) {
		case 0x00:
			iso_ctrl |= TRF7970A_ISO_CTRL_15693_SGL_1OF4_662;
			break;
		case ISO15693_REQ_FLAG_SUB_CARRIER:
			iso_ctrl |= TRF7970A_ISO_CTRL_15693_DBL_1OF4_667a;
			break;
		case ISO15693_REQ_FLAG_DATA_RATE:
			iso_ctrl |= TRF7970A_ISO_CTRL_15693_SGL_1OF4_2648;
			break;
		case (ISO15693_REQ_FLAG_SUB_CARRIER |
		      ISO15693_REQ_FLAG_DATA_RATE):
			iso_ctrl |= TRF7970A_ISO_CTRL_15693_DBL_1OF4_2669;
			break;
		}

		if (iso_ctrl != trf->iso_ctrl) {
			ret = trf7970a_write(trf, TRF7970A_ISO_CTRL, iso_ctrl);
			if (ret)
				return ret;

			trf->iso_ctrl = iso_ctrl;
		}

		if ((trf->framing == NFC_DIGITAL_FRAMING_ISO15693_T5T) &&
		    trf7970a_is_iso15693_write_or_lock(req[1]) &&
		    (req[0] & ISO15693_REQ_FLAG_OPTION))
			trf->issue_eof = true;
	}

	return 0;
}