esp.c: only transfer non-DMA MESSAGE OUT phase data for specific comm…

…ands

The contents of the FIFO should only be copied to cmdfifo for ESP commands that
are sending data to the SCSI bus, which are the SEL_* commands and the TI
command. Otherwise any incoming data should be held in the FIFO as normal.

This fixes booting of NetBSD m68k under the Q800 machine once again.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Helge Deller <deller@gmx.de>
Tested-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20240112125420.514425-78-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

hw/scsi/esp.c

@@ -712,14 +712,13 @@ static void esp_do_nodma(ESPState *s)
 
     switch (esp_get_phase(s)) {
     case STAT_MO:
-        /* Copy FIFO into cmdfifo */
-        n = esp_fifo_pop_buf(&s->fifo, buf, fifo8_num_used(&s->fifo));
-        n = MIN(fifo8_num_free(&s->cmdfifo), n);
-        fifo8_push_all(&s->cmdfifo, buf, n);
-        s->cmdfifo_cdb_offset += n;
-
         switch (s->rregs[ESP_CMD]) {
         case CMD_SELATN:
+            /* Copy FIFO into cmdfifo */
+            n = esp_fifo_pop_buf(&s->fifo, buf, fifo8_num_used(&s->fifo));
+            n = MIN(fifo8_num_free(&s->cmdfifo), n);
+            fifo8_push_all(&s->cmdfifo, buf, n);
+
             if (fifo8_num_used(&s->cmdfifo) >= 1) {
                 /* First byte received, switch to command phase */
                 esp_set_phase(s, STAT_CD);
@@ -734,6 +733,11 @@ static void esp_do_nodma(ESPState *s)
             break;
 
         case CMD_SELATNS:
+            /* Copy one byte from FIFO into cmdfifo */
+            n = esp_fifo_pop_buf(&s->fifo, buf, 1);
+            n = MIN(fifo8_num_free(&s->cmdfifo), n);
+            fifo8_push_all(&s->cmdfifo, buf, n);
+
             if (fifo8_num_used(&s->cmdfifo) >= 1) {
                 /* First byte received, stop in message out phase */
                 s->rregs[ESP_RSEQ] = SEQ_MO;
@@ -746,6 +750,11 @@ static void esp_do_nodma(ESPState *s)
             break;
 
         case CMD_TI:
+            /* Copy FIFO into cmdfifo */
+            n = esp_fifo_pop_buf(&s->fifo, buf, fifo8_num_used(&s->fifo));
+            n = MIN(fifo8_num_free(&s->cmdfifo), n);
+            fifo8_push_all(&s->cmdfifo, buf, n);
+
             /* ATN remains asserted until FIFO empty */
             s->cmdfifo_cdb_offset = fifo8_num_used(&s->cmdfifo);
             esp_set_phase(s, STAT_CD);