[axge] Handle non-gigabit link speeds

The ASIX USB NICs are capable of autodetecting the Ethernet link speed
and reporting it via PLSR but will not automatically update the
relevant GM and PS bits in MSR.  The result is that a non-gigabit link
will fail to send or receive any packets.

The interrupt endpoint used to report link state includes the values
of the PHY BMSR and LPA registers.  These are not sufficient to
differentiate between 100Mbps and 1000Mbps, since the LPA_NPAGE bit
does not necessarily indicate that the link partner is advertising
1000Mbps.

Extend axge_check_link() to write the MSR value based on the link
speed read from PLSR, and simplify the interrupt endpoint handler to
merely trigger a call to axge_check_link().

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/axge.c

@@ -213,6 +213,7 @@ static inline int axge_write_dword ( struct axge_device *axge,
 static int axge_check_link ( struct axge_device *axge ) {
 	struct net_device *netdev = axge->netdev;
 	uint8_t plsr;
+	uint16_t msr;
 	int rc;
 
 	/* Read physical link status register */
@@ -222,12 +223,28 @@ static int axge_check_link ( struct axge_device *axge ) {
 		return rc;
 	}
 
+	/* Write medium status register */
+	msr = cpu_to_le16 ( AXGE_MSR_FD | AXGE_MSR_RFC | AXGE_MSR_TFC |
+			    AXGE_MSR_RE );
+	if ( plsr & AXGE_PLSR_EPHY_1000 ) {
+		msr |= cpu_to_le16 ( AXGE_MSR_GM );
+	} else if ( plsr & AXGE_PLSR_EPHY_100 ) {
+		msr |= cpu_to_le16 ( AXGE_MSR_PS );
+	}
+	if ( ( rc = axge_write_word ( axge, AXGE_MSR, msr ) ) != 0 ) {
+		DBGC ( axge, "AXGE %p could not write MSR: %s\n",
+		       axge, strerror ( rc ) );
+		return rc;
+	}
+
 	/* Update link status */
 	if ( plsr & AXGE_PLSR_EPHY_ANY ) {
-		DBGC ( axge, "AXGE %p link up (PLSR %02x)\n", axge, plsr );
+		DBGC ( axge, "AXGE %p link up (PLSR %02x MSR %04x)\n",
+		       axge, plsr, msr );
 		netdev_link_up ( netdev );
 	} else {
-		DBGC ( axge, "AXGE %p link down (PLSR %02x)\n", axge, plsr );
+		DBGC ( axge, "AXGE %p link down (PLSR %02x MSR %04x)\n",
+		       axge, plsr, msr );
 		netdev_link_down ( netdev );
 	}
 
@@ -291,13 +308,8 @@ static void axge_intr_complete ( struct usb_endpoint *ep,
 
 	/* Extract link status */
 	link_ok = ( intr->link & cpu_to_le16 ( AXGE_INTR_LINK_PPLS ) );
-	if ( link_ok && ! netdev_link_ok ( netdev ) ) {
-		DBGC ( axge, "AXGE %p link up\n", axge );
-		netdev_link_up ( netdev );
-	} else if ( netdev_link_ok ( netdev ) && ! link_ok ) {
-		DBGC ( axge, "AXGE %p link down\n", axge );
-		netdev_link_down ( netdev );
-	}
+	if ( ( !! link_ok ) ^ ( !! netdev_link_ok ( netdev ) ) )
+		axge->check_link = 1;
 
 	/* Free I/O buffer */
 	free_iob ( iobuf );
@@ -544,10 +556,12 @@ static int axge_open ( struct net_device *netdev ) {
 	}
 
 	/* Update link status */
-	axge_check_link ( axge );
+	if ( ( rc = axge_check_link ( axge ) ) != 0 )
+		goto err_check_link;
 
 	return 0;
 
+ err_check_link:
 	axge_write_word ( axge, AXGE_RCR, 0 );
  err_write_rcr:
  err_write_mac:
@@ -605,6 +619,15 @@ static void axge_poll ( struct net_device *netdev ) {
 	/* Refill endpoints */
 	if ( ( rc = usbnet_refill ( &axge->usbnet ) ) != 0 )
 		netdev_rx_err ( netdev, NULL, rc );
+
+	/* Update link state, if applicable */
+	if ( axge->check_link ) {
+		if ( ( rc = axge_check_link ( axge ) ) == 0 ) {
+			axge->check_link = 0;
+		} else {
+			netdev_rx_err ( netdev, NULL, rc );
+		}
+	}
 }
 
 /** AXGE network device operations */
@@ -635,7 +658,6 @@ static int axge_probe ( struct usb_function *func,
 	struct net_device *netdev;
 	struct axge_device *axge;
 	uint16_t epprcr;
-	uint16_t msr;
 	uint8_t csr;
 	int rc;
 
@@ -705,28 +727,20 @@ static int axge_probe ( struct usb_function *func,
 		goto err_write_bicr;
 	}
 
-	/* Set medium status */
-	msr = cpu_to_le16 ( AXGE_MSR_GM | AXGE_MSR_FD | AXGE_MSR_RFC |
-			    AXGE_MSR_TFC | AXGE_MSR_RE );
-	if ( ( rc = axge_write_word ( axge, AXGE_MSR, msr ) ) != 0 ) {
-		DBGC ( axge, "AXGE %p could not write MSR: %s\n",
-		       axge, strerror ( rc ) );
-		goto err_write_msr;
-	}
-
 	/* Register network device */
 	if ( ( rc = register_netdev ( netdev ) ) != 0 )
 		goto err_register;
 
 	/* Update link status */
-	axge_check_link ( axge );
+	if ( ( rc = axge_check_link ( axge ) ) != 0 )
+		goto err_check_link;
 
 	usb_func_set_drvdata ( func, axge );
 	return 0;
 
+ err_check_link:
 	unregister_netdev ( netdev );
  err_register:
- err_write_msr:
  err_write_bicr:
  err_write_csr:
  err_write_epprcr_on:

src/drivers/net/axge.h

@@ -49,6 +49,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define AXGE_MSR_RFC			0x0010	/**< RX flow control enable */
 #define AXGE_MSR_TFC			0x0020	/**< TX flow control enable */
 #define AXGE_MSR_RE			0x0100	/**< Receive enable */
+#define AXGE_MSR_PS			0x0200	/**< 100Mbps port speed */
 
 /** Ethernet PHY Power and Reset Control Register */
 #define AXGE_EPPRCR 0x26
@@ -144,6 +145,8 @@ struct axge_device {
 	struct net_device *netdev;
 	/** USB network device */
 	struct usbnet_device usbnet;
+	/** Link state has changed */
+	int check_link;
 };
 
 /** Interrupt maximum fill level