net: usb: ax88179_178a: Implement ethtool_ops set_eeprom

The vendor driver does upon failing to read a valid MAC address from
EEPROM write the netdev's address back to EEPROM and invoking a EEPROM
reload operation. Based on this we can implement the ethtool_ops
set_eeprom and provide the means to populate the EEPROM from within
Linux.

It's worth noting that ax88179_get_eeprom() will return some default
data unless the content of the EEPROM is deemed "complete", so until the
EEPROM is fully populated (e.g. by running ethtool -e | ethtool -E)
data written with ax88179_set_eeprom() will appear not to stick.

The implementation is based on asix_set_eeprom(), from asix_common.c

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/ax88179_178a.c

@@ -31,6 +31,7 @@
 #define AX_ACCESS_PHY				0x02
 #define AX_ACCESS_EEPROM			0x04
 #define AX_ACCESS_EFUS				0x05
+#define AX_RELOAD_EEPROM_EFUSE			0x06
 #define AX_PAUSE_WATERLVL_HIGH			0x54
 #define AX_PAUSE_WATERLVL_LOW			0x55
 
@@ -611,6 +612,81 @@ ax88179_get_eeprom(struct net_device *net, struct ethtool_eeprom *eeprom,
 	return 0;
 }
 
+static int
+ax88179_set_eeprom(struct net_device *net, struct ethtool_eeprom *eeprom,
+		   u8 *data)
+{
+	struct usbnet *dev = netdev_priv(net);
+	u16 *eeprom_buff;
+	int first_word;
+	int last_word;
+	int ret;
+	int i;
+
+	netdev_dbg(net, "write EEPROM len %d, offset %d, magic 0x%x\n",
+		   eeprom->len, eeprom->offset, eeprom->magic);
+
+	if (eeprom->len == 0)
+		return -EINVAL;
+
+	if (eeprom->magic != AX88179_EEPROM_MAGIC)
+		return -EINVAL;
+
+	first_word = eeprom->offset >> 1;
+	last_word = (eeprom->offset + eeprom->len - 1) >> 1;
+
+	eeprom_buff = kmalloc_array(last_word - first_word + 1, sizeof(u16),
+				    GFP_KERNEL);
+	if (!eeprom_buff)
+		return -ENOMEM;
+
+	/* align data to 16 bit boundaries, read the missing data from
+	   the EEPROM */
+	if (eeprom->offset & 1) {
+		ret = ax88179_read_cmd(dev, AX_ACCESS_EEPROM, first_word, 1, 2,
+				       &eeprom_buff[0]);
+		if (ret < 0) {
+			netdev_err(net, "Failed to read EEPROM at offset 0x%02x.\n", first_word);
+			goto free;
+		}
+	}
+
+	if ((eeprom->offset + eeprom->len) & 1) {
+		ret = ax88179_read_cmd(dev, AX_ACCESS_EEPROM, last_word, 1, 2,
+				       &eeprom_buff[last_word - first_word]);
+		if (ret < 0) {
+			netdev_err(net, "Failed to read EEPROM at offset 0x%02x.\n", last_word);
+			goto free;
+		}
+	}
+
+	memcpy((u8 *)eeprom_buff + (eeprom->offset & 1), data, eeprom->len);
+
+	for (i = first_word; i <= last_word; i++) {
+		netdev_dbg(net, "write to EEPROM at offset 0x%02x, data 0x%04x\n",
+			   i, eeprom_buff[i - first_word]);
+		ret = ax88179_write_cmd(dev, AX_ACCESS_EEPROM, i, 1, 2,
+					&eeprom_buff[i - first_word]);
+		if (ret < 0) {
+			netdev_err(net, "Failed to write EEPROM at offset 0x%02x.\n", i);
+			goto free;
+		}
+		msleep(20);
+	}
+
+	/* reload EEPROM data */
+	ret = ax88179_write_cmd(dev, AX_RELOAD_EEPROM_EFUSE, 0x0000, 0, 0, NULL);
+	if (ret < 0) {
+		netdev_err(net, "Failed to reload EEPROM data\n");
+		goto free;
+	}
+
+	ret = 0;
+free:
+	kfree(eeprom_buff);
+	return ret;
+}
+
 static int ax88179_get_link_ksettings(struct net_device *net,
 				      struct ethtool_link_ksettings *cmd)
 {
@@ -822,6 +898,7 @@ static const struct ethtool_ops ax88179_ethtool_ops = {
 	.set_wol		= ax88179_set_wol,
 	.get_eeprom_len		= ax88179_get_eeprom_len,
 	.get_eeprom		= ax88179_get_eeprom,
+	.set_eeprom		= ax88179_set_eeprom,
 	.get_eee		= ax88179_get_eee,
 	.set_eee		= ax88179_set_eee,
 	.nway_reset		= usbnet_nway_reset,