net: fec: make PPS channel configurable

Depending on the SoC where the FEC is integrated into the PPS channel
might be routed to different timer instances. Make this configurable
from the devicetree.

When the related DT property is not present fallback to the previous
default and use channel 0.

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Rafael Beims <rafael.beims@toradex.com>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Reviewed-by: Csókás, Bence <csokas.bence@prolan.hu>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/freescale/fec_ptp.c

@@ -523,8 +523,6 @@ static int fec_ptp_enable(struct ptp_clock_info *ptp,
 	unsigned long flags;
 	int ret = 0;
 
-	fep->pps_channel = DEFAULT_PPS_CHANNEL;
-
 	if (rq->type == PTP_CLK_REQ_PPS) {
 		fep->reload_period = PPS_OUPUT_RELOAD_PERIOD;
 
@@ -706,12 +704,16 @@ void fec_ptp_init(struct platform_device *pdev, int irq_idx)
 {
 	struct net_device *ndev = platform_get_drvdata(pdev);
 	struct fec_enet_private *fep = netdev_priv(ndev);
+	struct device_node *np = fep->pdev->dev.of_node;
 	int irq;
 	int ret;
 
 	fep->ptp_caps.owner = THIS_MODULE;
 	strscpy(fep->ptp_caps.name, "fec ptp", sizeof(fep->ptp_caps.name));
 
+	fep->pps_channel = DEFAULT_PPS_CHANNEL;
+	of_property_read_u32(np, "fsl,pps-channel", &fep->pps_channel);
+
 	fep->ptp_caps.max_adj = 250000000;
 	fep->ptp_caps.n_alarm = 0;
 	fep->ptp_caps.n_ext_ts = 0;