ibmvnic: define map_txpool_buf_to_ltb()

Define a helper to map a given txpool buffer into its corresponding long
term buffer (LTB) and offset. Currently there is just one LTB per txpool
so the mapping is trivial. When we add support for multiple LTBs per
txpool, this helper will be more useful.
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
Signed-off-by: Dany Madden <drt@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/ibm/ibmvnic.c

@@ -364,6 +364,25 @@ static void map_rxpool_buf_to_ltb(struct ibmvnic_rx_pool *rxpool,
 	*offset = bufidx * rxpool->buff_size;
 }
 
+/**
+ * map_txpool_buf_to_ltb - Map given txpool buffer to offset in an LTB.
+ * @txpool: The transmit buffer pool containing buffer
+ * @bufidx: Index of buffer in txpool
+ * @ltbp: (Output) pointer to the long term buffer (LTB) containing the buffer
+ * @offset: (Output) offset of buffer in the LTB from @ltbp
+ *
+ * Map the given buffer identified by [txpool, bufidx] to an LTB in the
+ * pool and its corresponding offset.
+ */
+static void map_txpool_buf_to_ltb(struct ibmvnic_tx_pool *txpool,
+				  unsigned int bufidx,
+				  struct ibmvnic_long_term_buff **ltbp,
+				  unsigned int *offset)
+{
+	*ltbp = &txpool->long_term_buff;
+	*offset = bufidx * txpool->buf_size;
+}
+
 static void deactivate_rx_pools(struct ibmvnic_adapter *adapter)
 {
 	int i;
@@ -1931,6 +1950,7 @@ static netdev_tx_t ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev)
 	struct ibmvnic_ind_xmit_queue *ind_bufp;
 	struct ibmvnic_tx_buff *tx_buff = NULL;
 	struct ibmvnic_sub_crq_queue *tx_scrq;
+	struct ibmvnic_long_term_buff *ltb;
 	struct ibmvnic_tx_pool *tx_pool;
 	unsigned int tx_send_failed = 0;
 	netdev_tx_t ret = NETDEV_TX_OK;
@@ -1993,10 +2013,11 @@ static netdev_tx_t ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev)
 
 	tx_pool->free_map[tx_pool->consumer_index] = IBMVNIC_INVALID_MAP;
 
-	offset = bufidx * tx_pool->buf_size;
-	dst = tx_pool->long_term_buff.buff + offset;
+	map_txpool_buf_to_ltb(tx_pool, bufidx, &ltb, &offset);
+
+	dst = ltb->buff + offset;
 	memset(dst, 0, tx_pool->buf_size);
-	data_dma_addr = tx_pool->long_term_buff.addr + offset;
+	data_dma_addr = ltb->addr + offset;
 
 	if (skb_shinfo(skb)->nr_frags) {
 		int cur, i;
@@ -2040,7 +2061,7 @@ static netdev_tx_t ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev)
 			cpu_to_be32(bufidx | IBMVNIC_TSO_POOL_MASK);
 	else
 		tx_crq.v1.correlator = cpu_to_be32(bufidx);
-	tx_crq.v1.dma_reg = cpu_to_be16(tx_pool->long_term_buff.map_id);
+	tx_crq.v1.dma_reg = cpu_to_be16(ltb->map_id);
 	tx_crq.v1.sge_len = cpu_to_be32(skb->len);
 	tx_crq.v1.ioba = cpu_to_be64(data_dma_addr);