ixgbe: improve EEPROM read/write operations

Introduce buffered read/writes which greatly improves performance on
parts with large EEPROMs.

Previously reading/writing a word requires taking/releasing of synchronization
semaphores which adds 10ms to each operation. The optimization is to
read/write in buffers, but make sure the semaphore is not held for >500ms
according to the datasheet.

Since we can't read the EEPROM page size ixgbe_detect_eeprom_page_size() is
used to discover the EEPROM size when needed and keeps the result in
word_page_size for the rest of the run time.

Use buffered reads for ethtool -e.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Evan Swanson <evan.swanson@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ixgbe/ixgbe_82598.c b/drivers/net/ixgbe/ixgbe_82598.c
index 7a64f50..8179e50 100644
--- a/drivers/net/ixgbe/ixgbe_82598.c
+++ b/drivers/net/ixgbe/ixgbe_82598.c
@@ -1281,6 +1281,7 @@
 static struct ixgbe_eeprom_operations eeprom_ops_82598 = {
 	.init_params		= &ixgbe_init_eeprom_params_generic,
 	.read			= &ixgbe_read_eerd_generic,
+	.read_buffer		= &ixgbe_read_eerd_buffer_generic,
 	.calc_checksum          = &ixgbe_calc_eeprom_checksum_generic,
 	.validate_checksum	= &ixgbe_validate_eeprom_checksum_generic,
 	.update_checksum	= &ixgbe_update_eeprom_checksum_generic,