esp_scsi: correctly detect am53c974

The am53c974 returns the same ID as the FAS236, but implements
things slightly differently. So detect the am53c974 by checking
for ESP_CONFIG4 register.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

3 files changed, 33 insertions, 1 deletions

diff --git a/drivers/scsi/am53c974.c b/drivers/scsi/am53c974.c
index a42e8db057a4..6e88e38bd2a4 100644
--- a/drivers/scsi/am53c974.c
+++ b/drivers/scsi/am53c974.c
@@ -368,6 +368,8 @@ static void dc390_check_eeprom(struct esp *esp)
         }
         esp->scsi_id = EEbuf[DC390_EE_ADAPT_SCSI_ID];
         esp->num_tags = 2 << EEbuf[DC390_EE_TAG_CMD_NUM];
+        if (EEbuf[DC390_EE_MODE2] & DC390_EE_MODE2_ACTIVE_NEGATION)
+                esp->config4 |= ESP_CONFIG4_RADE | ESP_CONFIG4_RAE;
 }
 
 static int pci_esp_probe_one(struct pci_dev *pdev,
diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index 4366011cd400..3fb6a00934bc 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -268,6 +268,19 @@ static void esp_reset_esp(struct esp *esp)
         } else {
                 esp->min_period = ((5 * esp->ccycle) / 1000);
         }
+        if (esp->rev == FAS236) {
+                /*
+                 * The AM53c974 chip returns the same ID as FAS236;
+                 * try to configure glitch eater.
+                 */
+                u8 config4 = ESP_CONFIG4_GE1;
+                esp_write8(config4, ESP_CFG4);
+                config4 = esp_read8(ESP_CFG4);
+                if (config4 & ESP_CONFIG4_GE1) {
+                        esp->rev = PCSCSI;
+                        esp_write8(esp->config4, ESP_CFG4);
+                }
+        }
         esp->max_period = (esp->max_period + 3)>>2;
         esp->min_period = (esp->min_period + 3)>>2;
 
@@ -293,7 +306,8 @@ static void esp_reset_esp(struct esp *esp)
                 /* fallthrough... */
 
         case FAS236:
-                /* Fast 236 or HME */
+        case PCSCSI:
+                /* Fast 236, AM53c974 or HME */
                 esp_write8(esp->config2, ESP_CFG2);
                 if (esp->rev == FASHME) {
                         u8 cfg3 = esp->target[0].esp_config3;
@@ -2364,6 +2378,7 @@ static const char *esp_chip_names[] = {
         "FAS100A",
         "FAST",
         "FASHME",
+        "AM53C974",
 };
 
 static struct scsi_transport_template *esp_transport_template;
diff --git a/drivers/scsi/esp_scsi.h b/drivers/scsi/esp_scsi.h
index 5fa456cc5e8b..84dcbe4a6268 100644
--- a/drivers/scsi/esp_scsi.h
+++ b/drivers/scsi/esp_scsi.h
@@ -25,6 +25,7 @@
 #define ESP_CTEST       0x0aUL          /* wo  Chip test register      0x28  */
 #define ESP_CFG2        0x0bUL          /* rw  Second cfg register     0x2c  */
 #define ESP_CFG3        0x0cUL          /* rw  Third cfg register      0x30  */
+#define ESP_CFG4        0x0dUL          /* rw  Fourth cfg register     0x34  */
 #define ESP_TCHI        0x0eUL          /* rw  High bits transf count  0x38  */
 #define ESP_UID         ESP_TCHI        /* ro  Unique ID code          0x38  */
 #define FAS_RLO         ESP_TCHI        /* rw  HME extended counter    0x38  */
@@ -76,6 +77,18 @@
 #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 */
+
+#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)
+
 /* ESP command register read-write */
 /* Group 1 commands:  These may be sent at any point in time to the ESP
  *                    chip.  None of them can generate interrupts 'cept
@@ -254,6 +267,7 @@ enum esp_rev {
         FAS100A    = 0x04,
         FAST       = 0x05,
         FASHME     = 0x06,
+        PCSCSI     = 0x07,  /* AM53c974 */
 };
 
 struct esp_cmd_entry {
@@ -466,6 +480,7 @@ struct esp {
         u8                      bursts;
         u8                      config1;
         u8                      config2;
+        u8                      config4;
 
         u8                      scsi_id;
         u32                     scsi_id_mask;