From: Fugang Duan <fugang.duan@nxp.com>
Date: Mon, 15 Oct 2018 05:19:00 +0000
Subject: net: fec: don't dump RX FIFO register when not available
Git-commit: ec20a63aa8b8ec3223fb25cdb2a49f9f9dfda88c
Patch-mainline: v4.19
References: networking-stable-18_11_02

Commit db65f35f50e0 ("net: fec: add support of ethtool get_regs") introduce
ethool "--register-dump" interface to dump all FEC registers.

But not all silicon implementations of the Freescale FEC hardware module
have the FRBR (FIFO Receive Bound Register) and FRSR (FIFO Receive Start
Register) register, so we should not be trying to dump them on those that
don't.

To fix it we create a quirk flag, FEC_QUIRK_HAS_RFREG, and check it before
dump those RX FIFO registers.

Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/net/ethernet/freescale/fec.h      |    4 ++++
 drivers/net/ethernet/freescale/fec_main.c |   16 ++++++++++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -446,6 +446,10 @@ struct bufdesc_ex {
 #define FEC_QUIRK_HAS_COALESCE		(1 << 13)
 /* Interrupt doesn't wake CPU from deep idle */
 #define FEC_QUIRK_ERR006687		(1 << 14)
+/* Only i.MX25/i.MX27/i.MX28 controller supports FRBR,FRSR registers,
+ * those FIFO receive registers are resolved in other platforms.
+ */
+#define FEC_QUIRK_HAS_FRREG		(1 << 16)
 
 struct bufdesc_prop {
 	int qid;
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -89,14 +89,16 @@ static struct platform_device_id fec_dev
 		.driver_data = 0,
 	}, {
 		.name = "imx25-fec",
-		.driver_data = FEC_QUIRK_USE_GASKET,
+		.driver_data = FEC_QUIRK_USE_GASKET |
+			       FEC_QUIRK_HAS_FRREG,
 	}, {
 		.name = "imx27-fec",
-		.driver_data = 0,
+		.driver_data = FEC_QUIRK_HAS_FRREG,
 	}, {
 		.name = "imx28-fec",
 		.driver_data = FEC_QUIRK_ENET_MAC | FEC_QUIRK_SWAP_FRAME |
-				FEC_QUIRK_SINGLE_MDIO | FEC_QUIRK_HAS_RACC,
+				FEC_QUIRK_SINGLE_MDIO | FEC_QUIRK_HAS_RACC |
+				FEC_QUIRK_HAS_FRREG,
 	}, {
 		.name = "imx6q-fec",
 		.driver_data = FEC_QUIRK_ENET_MAC | FEC_QUIRK_HAS_GBIT |
@@ -2161,7 +2163,13 @@ static void fec_enet_get_regs(struct net
 	memset(buf, 0, regs->len);
 
 	for (i = 0; i < ARRAY_SIZE(fec_enet_register_offset); i++) {
-		off = fec_enet_register_offset[i] / 4;
+		off = fec_enet_register_offset[i];
+
+		if ((off == FEC_R_BOUND || off == FEC_R_FSTART) &&
+		    !(fep->quirks & FEC_QUIRK_HAS_FRREG))
+			continue;
+
+		off >>= 2;
 		buf[off] = readl(&theregs[off]);
 	}
 }