e1000: Rewrite EEPROM checksum error to give more information

As an aide to debugging, we should print out the expected value of the
EEPROM checksum in addition to just saying that it is wrong.

Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com>
Cc: Ben Warren <biggerbadderben@gmail.com>

drivers/net/e1000.c

@@ -876,29 +876,41 @@ e1000_read_eeprom(struct e1000_hw *hw, uint16_t offset,
  * If the the sum of the 64 16 bit words is 0xBABA, the EEPROM's checksum is
  * valid.
  *****************************************************************************/
-static int
-e1000_validate_eeprom_checksum(struct eth_device *nic)
+static int e1000_validate_eeprom_checksum(struct e1000_hw *hw)
 {
-	struct e1000_hw *hw = nic->priv;
-	uint16_t checksum = 0;
-	uint16_t i, eeprom_data;
+	uint16_t i, checksum, checksum_reg, *buf;
 
 	DEBUGFUNC();
 
-	for (i = 0; i < (EEPROM_CHECKSUM_REG + 1); i++) {
-		if (e1000_read_eeprom(hw, i, 1,  &eeprom_data) < 0) {
-			DEBUGOUT("EEPROM Read Error\n");
-			return -E1000_ERR_EEPROM;
-		}
-		checksum += eeprom_data;
+	/* Allocate a temporary buffer */
+	buf = malloc(sizeof(buf[0]) * (EEPROM_CHECKSUM_REG + 1));
+	if (!buf) {
+		E1000_ERR(hw->nic, "Unable to allocate EEPROM buffer!\n");
+		return -E1000_ERR_EEPROM;
 	}
 
-	if (checksum == (uint16_t) EEPROM_SUM) {
-		return 0;
-	} else {
-		DEBUGOUT("EEPROM Checksum Invalid\n");
+	/* Read the EEPROM */
+	if (e1000_read_eeprom(hw, 0, EEPROM_CHECKSUM_REG + 1, buf) < 0) {
+		E1000_ERR(hw->nic, "Unable to read EEPROM!\n");
 		return -E1000_ERR_EEPROM;
 	}
+
+	/* Compute the checksum */
+	for (i = 0; i < EEPROM_CHECKSUM_REG; i++)
+		checksum += buf[i];
+	checksum = ((uint16_t)EEPROM_SUM) - checksum;
+	checksum_reg = buf[i];
+
+	/* Verify it! */
+	if (checksum == checksum_reg)
+		return 0;
+
+	/* Hrm, verification failed, print an error */
+	E1000_ERR(hw->nic, "EEPROM checksum is incorrect!\n");
+	E1000_ERR(hw->nic, "  ...register was 0x%04hx, calculated 0x%04hx\n",
+			checksum_reg, checksum);
+
+	return -E1000_ERR_EEPROM;
 }
 
 /*****************************************************************************
@@ -5243,10 +5255,8 @@ e1000_initialize(bd_t * bis)
 			E1000_ERR(nic, "EEPROM is invalid!\n");
 			continue;
 		}
-		if (e1000_validate_eeprom_checksum(nic) < 0) {
-			E1000_ERR(nic, "EEPROM checksum is bad!\n");
+		if (e1000_validate_eeprom_checksum(hw))
 			continue;
-		}
 #endif
 		e1000_read_mac_addr(nic);
 		e1000_get_bus_type(hw);