+/* ESP config register 4 read-write, found only on am53c974 chips */
+#define ESP_CONFIG4_RADE 0x04 /* Active negation */
+#define ESP_CONFIG4_RAE 0x08 /* Active negation on REQ and ACK */
+#define ESP_CONFIG4_PWD 0x20 /* Reduced power feature */
+#define ESP_CONFIG4_GE0 0x40 /* Glitch eater bit 0 */
+#define ESP_CONFIG4_GE1 0x80 /* Glitch eater bit 1 */
+
+#define ESP_CONFIG_GE_12NS (0)
+#define ESP_CONFIG_GE_25NS (ESP_CONFIG_GE1)
+#define ESP_CONFIG_GE_35NS (ESP_CONFIG_GE0)
+#define ESP_CONFIG_GE_0NS (ESP_CONFIG_GE0 | ESP_CONFIG_GE1)
+