[PATCH 4.14 120/143] net: fec: dont dump RX FIFO register when not available

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Fugang Duan <fugang.duan@xxxxxxx>

[ Upstream commit ec20a63aa8b8ec3223fb25cdb2a49f9f9dfda88c ]

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@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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
@@ -451,6 +451,10 @@ struct bufdesc_ex {
  * initialisation.
  */
 #define FEC_QUIRK_MIB_CLEAR		(1 << 15)
+/* 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 | FEC_QUIRK_MIB_CLEAR,
+		.driver_data = FEC_QUIRK_USE_GASKET | FEC_QUIRK_MIB_CLEAR |
+			       FEC_QUIRK_HAS_FRREG,
 	}, {
 		.name = "imx27-fec",
-		.driver_data = FEC_QUIRK_MIB_CLEAR,
+		.driver_data = FEC_QUIRK_MIB_CLEAR | 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 |
@@ -2166,7 +2168,13 @@ 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]);
 	}
 }