net: fec: add C45 MDIO read/write support

IEEE 802.3ae clause 45 defines a modified MDIO protocol that uses a two
staged access model in order to increase the address space.

This patch adds support for C45 MDIO read and write accesses, which are
used whenever the MII_ADDR_C45 flag in the regnum argument is set.
In case it is not set, C22 accesses are used as before.

Signed-off-by: Marco Hartmann <[e-mail]>
Acked-by: Fugang Duan <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/freescale/fec_main.c

···
 
 /* FEC MII MMFR bits definition */
 #define FEC_MMFR_ST		(1 << 30)
+#define FEC_MMFR_ST_C45		(0)
 #define FEC_MMFR_OP_READ	(2 << 28)
+#define FEC_MMFR_OP_READ_C45	(3 << 28)
 #define FEC_MMFR_OP_WRITE	(1 << 28)
+#define FEC_MMFR_OP_ADDR_WRITE	(0)
 #define FEC_MMFR_PA(v)		((v & 0x1f) << 23)
 #define FEC_MMFR_RA(v)		((v & 0x1f) << 18)
 #define FEC_MMFR_TA		(2 << 16)
···
 	struct fec_enet_private *fep = bus->priv;
 	struct device *dev = &fep->pdev->dev;
 	unsigned long time_left;
-	int ret = 0;
+	int ret = 0, frame_start, frame_addr, frame_op;
+	bool is_c45 = !!(regnum & MII_ADDR_C45);
 
 	ret = pm_runtime_get_sync(dev);
 	if (ret < 0)
···
 
 	reinit_completion(&fep->mdio_done);
 
+	if (is_c45) {
+		frame_start = FEC_MMFR_ST_C45;
+
+		/* write address */
+		frame_addr = (regnum >> 16);
+		writel(frame_start | FEC_MMFR_OP_ADDR_WRITE |
+		       FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(frame_addr) |
+		       FEC_MMFR_TA | (regnum & 0xFFFF),
+		       fep->hwp + FEC_MII_DATA);
+
+		/* wait for end of transfer */
+		time_left = wait_for_completion_timeout(&fep->mdio_done,
+				usecs_to_jiffies(FEC_MII_TIMEOUT));
+		if (time_left == 0) {
+			netdev_err(fep->netdev, "MDIO address write timeout\n");
+			ret = -ETIMEDOUT;
+			goto out;
+		}
+
+		frame_op = FEC_MMFR_OP_READ_C45;
+
+	} else {
+		/* C22 read */
+		frame_op = FEC_MMFR_OP_READ;
+		frame_start = FEC_MMFR_ST;
+		frame_addr = regnum;
+	}
+
 	/* start a read op */
-	writel(FEC_MMFR_ST | FEC_MMFR_OP_READ |
-		FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(regnum) |
+	writel(frame_start | frame_op |
+		FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(frame_addr) |
 		FEC_MMFR_TA, fep->hwp + FEC_MII_DATA);
 
 	/* wait for end of transfer */
···
 	struct fec_enet_private *fep = bus->priv;
 	struct device *dev = &fep->pdev->dev;
 	unsigned long time_left;
-	int ret;
+	int ret, frame_start, frame_addr;
+	bool is_c45 = !!(regnum & MII_ADDR_C45);
 
 	ret = pm_runtime_get_sync(dev);
 	if (ret < 0)
···
 
 	reinit_completion(&fep->mdio_done);
 
+	if (is_c45) {
+		frame_start = FEC_MMFR_ST_C45;
+
+		/* write address */
+		frame_addr = (regnum >> 16);
+		writel(frame_start | FEC_MMFR_OP_ADDR_WRITE |
+		       FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(frame_addr) |
+		       FEC_MMFR_TA | (regnum & 0xFFFF),
+		       fep->hwp + FEC_MII_DATA);
+
+		/* wait for end of transfer */
+		time_left = wait_for_completion_timeout(&fep->mdio_done,
+			usecs_to_jiffies(FEC_MII_TIMEOUT));
+		if (time_left == 0) {
+			netdev_err(fep->netdev, "MDIO address write timeout\n");
+			ret = -ETIMEDOUT;
+			goto out;
+		}
+	} else {
+		/* C22 write */
+		frame_start = FEC_MMFR_ST;
+		frame_addr = regnum;
+	}
+
 	/* start a write op */
-	writel(FEC_MMFR_ST | FEC_MMFR_OP_WRITE |
-		FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(regnum) |
+	writel(frame_start | FEC_MMFR_OP_WRITE |
+		FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(frame_addr) |
 		FEC_MMFR_TA | FEC_MMFR_DATA(value),
 		fep->hwp + FEC_MII_DATA);
 
···
 		ret  = -ETIMEDOUT;
 	}
 
+out:
 	pm_runtime_mark_last_busy(dev);
 	pm_runtime_put_autosuspend(dev);