net/mlx5e: ethtool, Add support for EEPROM high pages query

Add the support to read additional EEPROM information from high pages.
Information for modules such as SFF-8436 and SFF-8636:
1) Application select table
2) User writable EEPROM
3) Thresholds and alarms

Signed-off-by: Erez Alfasi <[e-mail]>
Signed-off-by: Saeed Mahameed <[e-mail]>

drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c

···
 	struct mlx5e_priv *priv = netdev_priv(netdev);
 	struct mlx5_core_dev *dev = priv->mdev;
 	int size_read = 0;
-	u8 data[4];
+	u8 data[4] = {0};
 
 	size_read = mlx5_query_module_eeprom(dev, 0, 2, data);
 	if (size_read < 2)
···
 	switch (data[0]) {
 	case MLX5_MODULE_ID_QSFP:
 		modinfo->type       = ETH_MODULE_SFF_8436;
-		modinfo->eeprom_len = ETH_MODULE_SFF_8436_LEN;
+		modinfo->eeprom_len = ETH_MODULE_SFF_8436_MAX_LEN;
 		break;
 	case MLX5_MODULE_ID_QSFP_PLUS:
 	case MLX5_MODULE_ID_QSFP28:
 		/* data[1] = revision id */
 		if (data[0] == MLX5_MODULE_ID_QSFP28 || data[1] >= 0x3) {
 			modinfo->type       = ETH_MODULE_SFF_8636;
-			modinfo->eeprom_len = ETH_MODULE_SFF_8636_LEN;
+			modinfo->eeprom_len = ETH_MODULE_SFF_8636_MAX_LEN;
 		} else {
 			modinfo->type       = ETH_MODULE_SFF_8436;
-			modinfo->eeprom_len = ETH_MODULE_SFF_8436_LEN;
+			modinfo->eeprom_len = ETH_MODULE_SFF_8436_MAX_LEN;
 		}
 		break;
 	case MLX5_MODULE_ID_SFP:

drivers/net/ethernet/mellanox/mlx5/core/port.c

···
 	return 0;
 }
 
+static int mlx5_eeprom_page(int offset)
+{
+	if (offset < MLX5_EEPROM_PAGE_LENGTH)
+		/* Addresses between 0-255 - page 00 */
+		return 0;
+
+	/* Addresses between 256 - 639 belongs to pages 01, 02 and 03
+	 * For example, offset = 400 belongs to page 02:
+	 * 1 + ((400 - 256)/128) = 2
+	 */
+	return 1 + ((offset - MLX5_EEPROM_PAGE_LENGTH) /
+		    MLX5_EEPROM_HIGH_PAGE_LENGTH);
+}
+
+static int mlx5_eeprom_high_page_offset(int page_num)
+{
+	if (!page_num) /* Page 0 always start from low page */
+		return 0;
+
+	/* High page */
+	return page_num * MLX5_EEPROM_HIGH_PAGE_LENGTH;
+}
+
 int mlx5_query_module_eeprom(struct mlx5_core_dev *dev,
 			     u16 offset, u16 size, u8 *data)
 {
+	int module_num, page_num, status, err;
 	u32 out[MLX5_ST_SZ_DW(mcia_reg)];
 	u32 in[MLX5_ST_SZ_DW(mcia_reg)];
-	int module_num;
 	u16 i2c_addr;
-	int status;
-	int err;
 	void *ptr = MLX5_ADDR_OF(mcia_reg, out, dword_0);
 
 	err = mlx5_query_module_num(dev, &module_num);
···
 	memset(in, 0, sizeof(in));
 	size = min_t(int, size, MLX5_EEPROM_MAX_BYTES);
 
-	if (offset < MLX5_EEPROM_PAGE_LENGTH &&
-	    offset + size > MLX5_EEPROM_PAGE_LENGTH)
+	/* Get the page number related to the given offset */
+	page_num = mlx5_eeprom_page(offset);
+
+	/* Set the right offset according to the page number,
+	 * For page_num > 0, relative offset is always >= 128 (high page).
+	 */
+	offset -= mlx5_eeprom_high_page_offset(page_num);
+
+	if (offset + size > MLX5_EEPROM_PAGE_LENGTH)
 		/* Cross pages read, read until offset 256 in low page */
 		size -= offset + size - MLX5_EEPROM_PAGE_LENGTH;
 
···
 	MLX5_SET(mcia_reg, in, l, 0);
 	MLX5_SET(mcia_reg, in, module, module_num);
 	MLX5_SET(mcia_reg, in, i2c_device_address, i2c_addr);
-	MLX5_SET(mcia_reg, in, page_number, 0);
+	MLX5_SET(mcia_reg, in, page_number, page_num);
 	MLX5_SET(mcia_reg, in, device_address, offset);
 	MLX5_SET(mcia_reg, in, size, size);
 

include/linux/mlx5/port.h

···
 #define MLX5_I2C_ADDR_LOW		0x50
 #define MLX5_I2C_ADDR_HIGH		0x51
 #define MLX5_EEPROM_PAGE_LENGTH		256
+#define MLX5_EEPROM_HIGH_PAGE_LENGTH	128
 
 enum mlx5e_link_mode {
 	MLX5E_1000BASE_CX_SGMII	 = 0,