scsi: esp_scsi: Add support for FSC chip

The FSC (NCR53CF9x-2 / SYM53CF9x-2) has a different family code than QLogic
or Emulex parts. This caused it to be detected as a FAS100A.

Unforunately, this meant the configuration of the CONFIG3 register was
incorrect. This causes data transfer issues with FAST-SCSI targets.

The FSC also has the CONFIG4 register. It can be used to enable a feature
called Active Negation which should always be enabled according to the data
manual.

Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Finn Thain <[e-mail]>
Signed-off-by: Kars de Jong <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/esp_scsi.c

···
 /* Reset the ESP chip, _not_ the SCSI bus. */
 static void esp_reset_esp(struct esp *esp)
 {
-	u8 family_code, version;
-
 	/* Now reset the ESP chip */
 	scsi_esp_cmd(esp, ESP_CMD_RC);
 	scsi_esp_cmd(esp, ESP_CMD_NULL | ESP_CMD_DMA);
···
 	 */
 	esp->max_period = ((35 * esp->ccycle) / 1000);
 	if (esp->rev == FAST) {
-		version = esp_read8(ESP_UID);
-		family_code = (version & 0xf8) >> 3;
-		if (family_code == 0x02)
+		u8 family_code = ESP_FAMILY(esp_read8(ESP_UID));
+
+		if (family_code == ESP_UID_F236) {
 			esp->rev = FAS236;
-		else if (family_code == 0x0a)
+		} else if (family_code == ESP_UID_HME) {
 			esp->rev = FASHME; /* Version is usually '5'. */
-		else
+		} else if (family_code == ESP_UID_FSC) {
+			esp->rev = FSC;
+			/* Enable Active Negation */
+			esp_write8(ESP_CONFIG4_RADE, ESP_CFG4);
+		} else {
 			esp->rev = FAS100A;
+		}
 		esp->min_period = ((4 * esp->ccycle) / 1000);
 	} else {
 		esp->min_period = ((5 * esp->ccycle) / 1000);
···
 
 	case FAS236:
 	case PCSCSI:
-		/* Fast 236, AM53c974 or HME */
+	case FSC:
 		esp_write8(esp->config2, ESP_CFG2);
 		if (esp->rev == FASHME) {
 			u8 cfg3 = esp->target[0].esp_config3;
···
 	"ESP236",
 	"FAS236",
 	"AM53C974",
+	"53CF9x-2",
 	"FAS100A",
 	"FAST",
 	"FASHME",

drivers/scsi/esp_scsi.h

···
 #define ESP_CONFIG3_IMS       0x80     /* ID msg chk'ng        (esp/fas236)  */
 #define ESP_CONFIG3_OBPUSH    0x80     /* Push odd-byte to dma (hme)         */
 
-/* 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 */
+/* ESP config register 4 read-write */
+#define ESP_CONFIG4_BBTE      0x01     /* Back-to-back transfers     (fsc)   */
+#define ESP_CONGIG4_TEST      0x02     /* Transfer counter test mode (fsc)   */
+#define ESP_CONFIG4_RADE      0x04     /* Active negation   (am53c974/fsc)   */
+#define ESP_CONFIG4_RAE       0x08     /* Act. negation REQ/ACK (am53c974)   */
+#define ESP_CONFIG4_PWD       0x20     /* Reduced power feature (am53c974)   */
+#define ESP_CONFIG4_GE0       0x40     /* Glitch eater bit 0    (am53c974)   */
+#define ESP_CONFIG4_GE1       0x80     /* Glitch eater bit 1    (am53c974)   */
 
 #define ESP_CONFIG_GE_12NS    (0)
 #define ESP_CONFIG_GE_25NS    (ESP_CONFIG_GE1)
···
 #define ESP_TEST_TS           0x04     /* Tristate test mode */
 
 /* ESP unique ID register read-only, found on fas236+fas100a only */
+#define ESP_UID_FAM           0xf8     /* ESP family bitmask */
+
+#define ESP_FAMILY(uid) (((uid) & ESP_UID_FAM) >> 3)
+
+/* Values for the ESP family bits */
 #define ESP_UID_F100A         0x00     /* ESP FAS100A  */
 #define ESP_UID_F236          0x02     /* ESP FAS236   */
-#define ESP_UID_REV           0x07     /* ESP revision */
-#define ESP_UID_FAM           0xf8     /* ESP family   */
+#define ESP_UID_HME           0x0a     /* FAS HME      */
+#define ESP_UID_FSC           0x14     /* NCR/Symbios Logic 53CF9x-2 */
 
 /* ESP fifo flags register read-only */
 /* Note that the following implies a 16 byte FIFO on the ESP. */
···
 	ESP236,
 	FAS236,
 	PCSCSI,  /* AM53c974 */
+	FSC,     /* NCR/Symbios Logic 53CF9x-2 */
 	FAS100A,
 	FAST,
 	FASHME,