net: ethernet: oa_tc6: add helper function to enable zero align rx frame

Zero align receive frame feature can be enabled to align all receive
ethernet frames data to start at the beginning of any receive data chunk
payload with a start word offset (SWO) of zero. Receive frames may begin
anywhere within the receive data chunk payload when this feature is not
enabled.

Reviewed-by: Andrew Lunn <[e-mail]>
Signed-off-by: Parthiban Veerasooran <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/oa_tc6.c

···
 /* Configuration Register #0 */
 #define OA_TC6_REG_CONFIG0			0x0004
 #define CONFIG0_SYNC				BIT(15)
+#define CONFIG0_ZARFE_ENABLE			BIT(12)
 
 /* Status Register #0 */
 #define OA_TC6_REG_STATUS0			0x0008
···
 
 	return IRQ_HANDLED;
 }
+
+/**
+ * oa_tc6_zero_align_receive_frame_enable - function to enable zero align
+ * receive frame feature.
+ * @tc6: oa_tc6 struct.
+ *
+ * Return: 0 on success otherwise failed.
+ */
+int oa_tc6_zero_align_receive_frame_enable(struct oa_tc6 *tc6)
+{
+	u32 regval;
+	int ret;
+
+	ret = oa_tc6_read_register(tc6, OA_TC6_REG_CONFIG0, &regval);
+	if (ret)
+		return ret;
+
+	/* Set Zero-Align Receive Frame Enable */
+	regval |= CONFIG0_ZARFE_ENABLE;
+
+	return oa_tc6_write_register(tc6, OA_TC6_REG_CONFIG0, regval);
+}
+EXPORT_SYMBOL_GPL(oa_tc6_zero_align_receive_frame_enable);
 
 /**
  * oa_tc6_start_xmit - function for sending the tx skb which consists ethernet

include/linux/oa_tc6.h

···
 int oa_tc6_read_registers(struct oa_tc6 *tc6, u32 address, u32 value[],
 			  u8 length);
 netdev_tx_t oa_tc6_start_xmit(struct oa_tc6 *tc6, struct sk_buff *skb);
+int oa_tc6_zero_align_receive_frame_enable(struct oa_tc6 *tc6);