asix: Add support for programming the EEPROM

This patch adds the asix_set_eeprom() function to provide support for
programming the configuration EEPROM via ethtool.

Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
index 0b5b2d3..774d9ce 100644
--- a/drivers/net/usb/asix_common.c
+++ b/drivers/net/usb/asix_common.c
@@ -516,6 +516,87 @@
 	return 0;
 }
 
+int asix_set_eeprom(struct net_device *net, struct ethtool_eeprom *eeprom,
+		    u8 *data)
+{
+	struct usbnet *dev = netdev_priv(net);
+	u16 *eeprom_buff;
+	int first_word, last_word;
+	int i;
+	int ret;
+
+	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 != AX_EEPROM_MAGIC)
+		return -EINVAL;
+
+	first_word = eeprom->offset >> 1;
+	last_word = (eeprom->offset + eeprom->len - 1) >> 1;
+
+	eeprom_buff = kmalloc(sizeof(u16) * (last_word - first_word + 1),
+			      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 = asix_read_cmd(dev, AX_CMD_READ_EEPROM, first_word, 0, 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 = asix_read_cmd(dev, AX_CMD_READ_EEPROM, last_word, 0, 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);
+
+	/* write data to EEPROM */
+	ret = asix_write_cmd(dev, AX_CMD_WRITE_ENABLE, 0x0000, 0, 0, NULL);
+	if (ret < 0) {
+		netdev_err(net, "Failed to enable EEPROM write\n");
+		goto free;
+	}
+	msleep(20);
+
+	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 = asix_write_cmd(dev, AX_CMD_WRITE_EEPROM, i,
+				     eeprom_buff[i - first_word], 0, NULL);
+		if (ret < 0) {
+			netdev_err(net, "Failed to write EEPROM at offset 0x%02x.\n",
+				   i);
+			goto free;
+		}
+		msleep(20);
+	}
+
+	ret = asix_write_cmd(dev, AX_CMD_WRITE_DISABLE, 0x0000, 0, 0, NULL);
+	if (ret < 0) {
+		netdev_err(net, "Failed to disable EEPROM write\n");
+		goto free;
+	}
+
+	ret = 0;
+free:
+	kfree(eeprom_buff);
+	return ret;
+}
+
 void asix_get_drvinfo(struct net_device *net, struct ethtool_drvinfo *info)
 {
 	/* Inherit standard device info */