sky2: EEPROM read/write bug fixes

Cleanup and harden the routines accessing the EEPROM.
  1. Prevent spin forever waiting for the TWSI bus
  2. Fix write eeprom to write full words rather than only 16 bits
    Luckly the vendor doesn't provide EEPROM in Linux format so it must never
    have been used.
  3. Don't allow partial eeprom writes, not needed, not safe.

These are non-urgent bug fixes.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/net/sky2.c

@@ -3732,27 +3732,63 @@ static int sky2_get_eeprom_len(struct net_device *dev)
 	return 1 << ( ((reg2 & PCI_VPD_ROM_SZ) >> 14) + 8);
 }
 
-static u32 sky2_vpd_read(struct sky2_hw *hw, int cap, u16 offset)
+static int sky2_vpd_wait(const struct sky2_hw *hw, int cap, u16 busy)
 {
+	unsigned long start = jiffies;
+
+	while ( (sky2_pci_read16(hw, cap + PCI_VPD_ADDR) & PCI_VPD_ADDR_F) == busy) {
+		/* Can take up to 10.6 ms for write */
+		if (time_after(jiffies, start + HZ/4)) {
+			dev_err(&hw->pdev->dev, PFX "VPD cycle timed out");
+			return -ETIMEDOUT;
+		}
+		mdelay(1);
+	}
+
+	return 0;
+}
+
+static int sky2_vpd_read(struct sky2_hw *hw, int cap, void *data,
+			 u16 offset, size_t length)
+{
+	int rc = 0;
+
+	while (length > 0) {
 		u32 val;
 
 		sky2_pci_write16(hw, cap + PCI_VPD_ADDR, offset);
-
-	do {
-		offset = sky2_pci_read16(hw, cap + PCI_VPD_ADDR);
-	} while (!(offset & PCI_VPD_ADDR_F));
+		rc = sky2_vpd_wait(hw, cap, 0);
+		if (rc)
+			break;
 
 		val = sky2_pci_read32(hw, cap + PCI_VPD_DATA);
-	return val;
+
+		memcpy(data, &val, min(sizeof(val), length));
+		offset += sizeof(u32);
+		data += sizeof(u32);
+		length -= sizeof(u32);
+	}
+
+	return rc;
 }
 
-static void sky2_vpd_write(struct sky2_hw *hw, int cap, u16 offset, u32 val)
+static int sky2_vpd_write(struct sky2_hw *hw, int cap, const void *data,
+			  u16 offset, unsigned int length)
 {
-	sky2_pci_write16(hw, cap + PCI_VPD_DATA, val);
+	unsigned int i;
+	int rc = 0;
+
+	for (i = 0; i < length; i += sizeof(u32)) {
+		u32 val = *(u32 *)(data + i);
+
+		sky2_pci_write32(hw, cap + PCI_VPD_DATA, val);
 		sky2_pci_write32(hw, cap + PCI_VPD_ADDR, offset | PCI_VPD_ADDR_F);
-	do {
-		offset = sky2_pci_read16(hw, cap + PCI_VPD_ADDR);
-	} while (offset & PCI_VPD_ADDR_F);
+
+		rc = sky2_vpd_wait(hw, cap, PCI_VPD_ADDR_F);
+		if (rc)
+			break;
+	}
+	return rc;
 }
 
 static int sky2_get_eeprom(struct net_device *dev, struct ethtool_eeprom *eeprom,
@@ -3760,24 +3796,13 @@ static int sky2_get_eeprom(struct net_device *dev, struct ethtool_eeprom *eeprom
 {
 	struct sky2_port *sky2 = netdev_priv(dev);
 	int cap = pci_find_capability(sky2->hw->pdev, PCI_CAP_ID_VPD);
-	int length = eeprom->len;
-	u16 offset = eeprom->offset;
 
 	if (!cap)
 		return -EINVAL;
 
 	eeprom->magic = SKY2_EEPROM_MAGIC;
 
-	while (length > 0) {
-		u32 val = sky2_vpd_read(sky2->hw, cap, offset);
-		int n = min_t(int, length, sizeof(val));
-
-		memcpy(data, &val, n);
-		length -= n;
-		data += n;
-		offset += n;
-	}
-	return 0;
+	return sky2_vpd_read(sky2->hw, cap, data, eeprom->offset, eeprom->len);
 }
 
 static int sky2_set_eeprom(struct net_device *dev, struct ethtool_eeprom *eeprom,
@@ -3785,8 +3810,6 @@ static int sky2_set_eeprom(struct net_device *dev, struct ethtool_eeprom *eeprom
 {
 	struct sky2_port *sky2 = netdev_priv(dev);
 	int cap = pci_find_capability(sky2->hw->pdev, PCI_CAP_ID_VPD);
-	int length = eeprom->len;
-	u16 offset = eeprom->offset;
 
 	if (!cap)
 		return -EINVAL;
@@ -3794,21 +3817,11 @@ static int sky2_set_eeprom(struct net_device *dev, struct ethtool_eeprom *eeprom
 	if (eeprom->magic != SKY2_EEPROM_MAGIC)
 		return -EINVAL;
 
-	while (length > 0) {
-		u32 val;
-		int n = min_t(int, length, sizeof(val));
-
-		if (n < sizeof(val))
-			val = sky2_vpd_read(sky2->hw, cap, offset);
-		memcpy(&val, data, n);
-
-		sky2_vpd_write(sky2->hw, cap, offset, val);
+	/* Partial writes not supported */
+	if ((eeprom->offset & 3) || (eeprom->len & 3))
+		return -EINVAL;
 
-		length -= n;
-		data += n;
-		offset += n;
-	}
-	return 0;
+	return sky2_vpd_write(sky2->hw, cap, data, eeprom->offset, eeprom->len);
 }