phy: mvebu-a3700-comphy: Inform users if their firmware is too old

PHY configuration has been implemented in the firmware and accessed
through SMC calls. In the past, it worked magically if the bootloader
was correctly doing the initializations.

With up-to-date bindings, the kernel will need a recent firmware in
order to do the initializations himself (we assume people must update
their firmware along with their kernel).

People might not understand why IPs that were working correctly before
stopped to be probed suddendly. In this case, let's advise the users
to update their firmware with a visual warning.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/marvell/phy-mvebu-a3700-comphy.c

@@ -26,6 +26,7 @@
 #define COMPHY_SIP_POWER_ON			0x82000001
 #define COMPHY_SIP_POWER_OFF			0x82000002
 #define COMPHY_SIP_PLL_LOCK			0x82000003
+#define COMPHY_FW_NOT_SUPPORTED			(-1)
 
 #define COMPHY_FW_MODE_SATA			0x1
 #define COMPHY_FW_MODE_SGMII			0x2
@@ -169,6 +170,7 @@ static int mvebu_a3700_comphy_power_on(struct phy *phy)
 	struct mvebu_a3700_comphy_lane *lane = phy_get_drvdata(phy);
 	u32 fw_param;
 	int fw_mode;
+	int ret;
 
 	fw_mode = mvebu_a3700_comphy_get_fw_mode(lane->id, lane->port,
 						 lane->mode, lane->submode);
@@ -217,7 +219,12 @@ static int mvebu_a3700_comphy_power_on(struct phy *phy)
 		return -ENOTSUPP;
 	}
 
-	return mvebu_a3700_comphy_smc(COMPHY_SIP_POWER_ON, lane->id, fw_param);
+	ret = mvebu_a3700_comphy_smc(COMPHY_SIP_POWER_ON, lane->id, fw_param);
+	if (ret == COMPHY_FW_NOT_SUPPORTED)
+		dev_err(lane->dev,
+			"unsupported SMC call, try updating your firmware\n");
+
+	return ret;
 }
 
 static int mvebu_a3700_comphy_power_off(struct phy *phy)