net/macb: ethtool interface: add register dump feature

Add macb_get_regs() ethtool function and its helper function:
macb_get_regs_len().
The version field is deduced from the IP revision which gives the
"MACB or GEM" information. An additional version field is reserved.
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Reviewed-by: Ben Hutchings <bhutchings@solarflare.com>
Tested-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cadence/macb.c

@@ -1273,9 +1273,49 @@ static int macb_set_settings(struct net_device *dev, struct ethtool_cmd *cmd)
 	return phy_ethtool_sset(phydev, cmd);
 }
 
+static int macb_get_regs_len(struct net_device *netdev)
+{
+	return MACB_GREGS_NBR * sizeof(u32);
+}
+
+static void macb_get_regs(struct net_device *dev, struct ethtool_regs *regs,
+			  void *p)
+{
+	struct macb *bp = netdev_priv(dev);
+	unsigned int tail, head;
+	u32 *regs_buff = p;
+
+	regs->version = (macb_readl(bp, MID) & ((1 << MACB_REV_SIZE) - 1))
+			| MACB_GREGS_VERSION;
+
+	tail = macb_tx_ring_wrap(bp->tx_tail);
+	head = macb_tx_ring_wrap(bp->tx_head);
+
+	regs_buff[0]  = macb_readl(bp, NCR);
+	regs_buff[1]  = macb_or_gem_readl(bp, NCFGR);
+	regs_buff[2]  = macb_readl(bp, NSR);
+	regs_buff[3]  = macb_readl(bp, TSR);
+	regs_buff[4]  = macb_readl(bp, RBQP);
+	regs_buff[5]  = macb_readl(bp, TBQP);
+	regs_buff[6]  = macb_readl(bp, RSR);
+	regs_buff[7]  = macb_readl(bp, IMR);
+
+	regs_buff[8]  = tail;
+	regs_buff[9]  = head;
+	regs_buff[10] = macb_tx_dma(bp, tail);
+	regs_buff[11] = macb_tx_dma(bp, head);
+
+	if (macb_is_gem(bp)) {
+		regs_buff[12] = gem_readl(bp, USRIO);
+		regs_buff[13] = gem_readl(bp, DMACFG);
+	}
+}
+
 const struct ethtool_ops macb_ethtool_ops = {
 	.get_settings		= macb_get_settings,
 	.set_settings		= macb_set_settings,
+	.get_regs_len		= macb_get_regs_len,
+	.get_regs		= macb_get_regs,
 	.get_link		= ethtool_op_get_link,
 	.get_ts_info		= ethtool_op_get_ts_info,
 };

drivers/net/ethernet/cadence/macb.h

@@ -10,6 +10,9 @@
 #ifndef _MACB_H
 #define _MACB_H
 
+#define MACB_GREGS_NBR 16
+#define MACB_GREGS_VERSION 1
+
 /* MACB register offsets */
 #define MACB_NCR				0x0000
 #define MACB_NCFGR				0x0004