drivers: net: xgene: Get channel number from device binding

BugLink: https://launchpad.net/bugs/1632739

This patch gets ethernet to CPU channel (prefetch buffer number) from
the newly added 'channel' property, thus decoupling Linux driver from
resource management.
Signed-off-by: Iyappan Subramanian <isubramanian@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 2a37daa6 yakkety)
Signed-off-by: Craig Magina <craig.magina@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

drivers/net/ethernet/apm/xgene/xgene_enet_main.c

@@ -973,6 +973,17 @@ static enum xgene_ring_owner xgene_derive_ring_owner(struct xgene_enet_pdata *p)
 	return owner;
 }
 
+static u8 xgene_start_cpu_bufnum(struct xgene_enet_pdata *pdata)
+{
+	struct device *dev = &pdata->pdev->dev;
+	u32 cpu_bufnum;
+	int ret;
+
+	ret = device_property_read_u32(dev, "channel", &cpu_bufnum);
+
+	return (!ret) ? cpu_bufnum : pdata->cpu_bufnum;
+}
+
 static int xgene_enet_create_desc_rings(struct net_device *ndev)
 {
 	struct xgene_enet_pdata *pdata = netdev_priv(ndev);
@@ -981,13 +992,15 @@ static int xgene_enet_create_desc_rings(struct net_device *ndev)
 	struct xgene_enet_desc_ring *buf_pool = NULL;
 	enum xgene_ring_owner owner;
 	dma_addr_t dma_exp_bufs;
-	u8 cpu_bufnum = pdata->cpu_bufnum;
+	u8 cpu_bufnum;
 	u8 eth_bufnum = pdata->eth_bufnum;
 	u8 bp_bufnum = pdata->bp_bufnum;
 	u16 ring_num = pdata->ring_num;
 	u16 ring_id;
 	int i, ret, size;
 
+	cpu_bufnum = xgene_start_cpu_bufnum(pdata);
+
 	for (i = 0; i < pdata->rxq_cnt; i++) {
 		/* allocate rx descriptor ring */
 		owner = xgene_derive_ring_owner(pdata);