ide/via: Fix BAR4 value in legacy mode

Return default value in legacy mode for BAR4 when unset. This can't be
set in reset method because BARs are cleared on reset so we return it
instead when BARs are read in legacy mode. This fixes UDMA on amigaone
with AmigaOS.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Message-ID: <20231125140135.AF6A075A4C3@zero.eik.bme.hu>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

hw/ide/via.c

@@ -163,14 +163,19 @@ static uint32_t via_ide_cfg_read(PCIDevice *pd, uint32_t addr, int len)
     uint32_t val = pci_default_read_config(pd, addr, len);
     uint8_t mode = pd->config[PCI_CLASS_PROG];
 
-    if ((mode & 0xf) == 0xa && ranges_overlap(addr, len,
-                                              PCI_BASE_ADDRESS_0, 16)) {
-        /* BARs always read back zero in legacy mode */
-        for (int i = addr; i < addr + len; i++) {
-            if (i >= PCI_BASE_ADDRESS_0 && i < PCI_BASE_ADDRESS_0 + 16) {
-                val &= ~(0xffULL << ((i - addr) << 3));
+    if ((mode & 0xf) == 0xa) {
+        if (ranges_overlap(addr, len, PCI_BASE_ADDRESS_0, 16)) {
+            /* BARs 0-3 always read back zero in legacy mode */
+            for (int i = addr; i < addr + len; i++) {
+                if (i >= PCI_BASE_ADDRESS_0 && i < PCI_BASE_ADDRESS_0 + 16) {
+                    val &= ~(0xffULL << ((i - addr) << 3));
+                }
             }
         }
+        if (addr == PCI_BASE_ADDRESS_4 && val == PCI_BASE_ADDRESS_SPACE_IO) {
+            /* BAR4 default value if unset */
+            val = 0xcc00 | PCI_BASE_ADDRESS_SPACE_IO;
+        }
     }
 
     return val;