net: stmmac: Fix PTP ref clock for Tegra234

Since commit 030ce91 ("net: stmmac: make sure that ptp_rate is not
0 before configuring timestamping") was added the following error is
observed on Tegra234:

 ERR KERN tegra-mgbe 6800000.ethernet eth0: Invalid PTP clock rate
 WARNING KERN tegra-mgbe 6800000.ethernet eth0: PTP init failed

It turns out that the Tegra234 device-tree binding defines the PTP ref
clock name as 'ptp-ref' and not 'ptp_ref' and the above commit now
exposes this and that the PTP clock is not configured correctly.

In order to update device-tree to use the correct 'ptp_ref' name, update
the Tegra MGBE driver to use 'ptp_ref' by default and fallback to using
'ptp-ref' if this clock name is present.

Fixes: d8ca113 ("net: stmmac: tegra: Add MGBE support")
Signed-off-by: Jon Hunter <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: jonhunter

drivers/net/ethernet/stmicro/stmmac/dwmac-tegra.c

@@ -9,7 +9,7 @@
 #include "stmmac_platform.h"
 
 static const char *const mgbe_clks[] = {
-	"rx-pcs", "tx", "tx-pcs", "mac-divider", "mac", "mgbe", "ptp-ref", "mac"
+	"rx-pcs", "tx", "tx-pcs", "mac-divider", "mac", "mgbe", "ptp_ref", "mac"
 };
 
 struct tegra_mgbe {
@@ -215,6 +215,7 @@ static int tegra_mgbe_probe(struct platform_device *pdev)
 {
 	struct plat_stmmacenet_data *plat;
 	struct stmmac_resources res;
+	bool use_legacy_ptp = false;
 	struct tegra_mgbe *mgbe;
 	int irq, err, i;
 	u32 value;
@@ -257,9 +258,23 @@ static int tegra_mgbe_probe(struct platform_device *pdev)
 	if (!mgbe->clks)
 		return -ENOMEM;
 
-	for (i = 0; i <  ARRAY_SIZE(mgbe_clks); i++)
+	/* Older device-trees use 'ptp-ref' rather than 'ptp_ref'.
+	 * Fall back when the legacy name is present.
+	 */
+	if (of_property_match_string(pdev->dev.of_node, "clock-names",
+				     "ptp-ref") >= 0)
+		use_legacy_ptp = true;
+
+	for (i = 0; i < ARRAY_SIZE(mgbe_clks); i++) {
 		mgbe->clks[i].id = mgbe_clks[i];
 
+		if (use_legacy_ptp && !strcmp(mgbe_clks[i], "ptp_ref")) {
+			dev_warn(mgbe->dev,
+				 "Device-tree update needed for PTP clock!\n");
+			mgbe->clks[i].id = "ptp-ref";
+		}
+	}
+
 	err = devm_clk_bulk_get(mgbe->dev, ARRAY_SIZE(mgbe_clks), mgbe->clks);
 	if (err < 0)
 		return err;