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>

1 files changed, 16 insertions, 1 deletions

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;