net: dsa: rtl8366rb: Support port 4 (WAN)

The totally undocumented IO mode needs to be set to enumerator
0 to enable port 4 also known as WAN in most configurations,
for ordinary traffic. The 3 bits in the register come up as
010 after reset, but need to be set to 000.

The Realtek source code contains a name for these bits, but
no explanation of what the 8 different IO modes may be.

Set it to zero for the time being and drop a comment so
people know what is going on if they run into trouble. This
"mode zero" works fine with the D-Link DIR-685 with
RTL8366RB.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/net/dsa/rtl8366rb.c b/drivers/net/dsa/rtl8366rb.c
index 1e55b9bf8b56..a4d5049df692 100644
--- a/drivers/net/dsa/rtl8366rb.c
+++ b/drivers/net/dsa/rtl8366rb.c
@@ -48,6 +48,23 @@
 #define RTL8366RB_SSCR2                         0x0004
 #define RTL8366RB_SSCR2_DROP_UNKNOWN_DA         BIT(0)
 
+/* Port Mode Control registers */
+#define RTL8366RB_PMC0                          0x0005
+#define RTL8366RB_PMC0_SPI                      BIT(0)
+#define RTL8366RB_PMC0_EN_AUTOLOAD              BIT(1)
+#define RTL8366RB_PMC0_PROBE                    BIT(2)
+#define RTL8366RB_PMC0_DIS_BISR                 BIT(3)
+#define RTL8366RB_PMC0_ADCTEST                  BIT(4)
+#define RTL8366RB_PMC0_SRAM_DIAG                BIT(5)
+#define RTL8366RB_PMC0_EN_SCAN                  BIT(6)
+#define RTL8366RB_PMC0_P4_IOMODE_SHIFT          7
+#define RTL8366RB_PMC0_P4_IOMODE_MASK           GENMASK(9, 7)
+#define RTL8366RB_PMC0_P5_IOMODE_SHIFT          10
+#define RTL8366RB_PMC0_P5_IOMODE_MASK           GENMASK(12, 10)
+#define RTL8366RB_PMC0_SDSMODE_SHIFT            13
+#define RTL8366RB_PMC0_SDSMODE_MASK             GENMASK(15, 13)
+#define RTL8366RB_PMC1                          0x0006
+
 /* Port Mirror Control Register */
 #define RTL8366RB_PMCR                          0x0007
 #define RTL8366RB_PMCR_SOURCE_PORT(a)           (a)
@@ -860,6 +877,19 @@ static int rtl8366rb_setup(struct dsa_switch *ds)
         if (ret)
                 return ret;
 
+        /* Port 4 setup: this enables Port 4, usually the WAN port,
+         * common PHY IO mode is apparently mode 0, and this is not what
+         * the port is initialized to. There is no explanation of the
+         * IO modes in the Realtek source code, if your WAN port is
+         * connected to something exotic such as fiber, then this might
+         * be worth experimenting with.
+         */
+        ret = regmap_update_bits(smi->map, RTL8366RB_PMC0,
+                                 RTL8366RB_PMC0_P4_IOMODE_MASK,
+                                 0 << RTL8366RB_PMC0_P4_IOMODE_SHIFT);
+        if (ret)
+                return ret;
+
         /* Discard VLAN tagged packets if the port is not a member of
          * the VLAN with which the packets is associated.
          */