csm: Fix boot priority translation

Explicitly handle the BBS_DO_NOT_BOOT_FROM and BBS_IGNORE_ENTRY values.

Also add one to the other priority values, as find_prio() does for
entries from bootorder. SeaBIOS uses zero for an item explicitly
selected in interactive_bootmenu().

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

1 files changed, 20 insertions, 3 deletions

diff --git a/src/fw/csm.c b/src/fw/csm.c
index 3fcc252..8359bcb 100644
--- a/src/fw/csm.c
+++ b/src/fw/csm.c
@@ -319,6 +319,23 @@ handle_csm(struct bregs *regs)
     csm_return(regs);
 }
 
+static int csm_prio_to_seabios(u16 csm_prio)
+{
+    switch (csm_prio) {
+    case BBS_DO_NOT_BOOT_FROM:
+    case BBS_IGNORE_ENTRY:
+        return -1;
+
+    case BBS_LOWEST_PRIORITY:
+    case BBS_UNPRIORITIZED_ENTRY:
+    default:
+        // SeaBIOS default priorities start at 1, with 0 being used for
+        // an item explicitly selected from interactive_bootmenu().
+        // As in find_prio(), add 1 to the value being returned.
+        return csm_prio + 1;
+    }
+}
+
 int csm_bootprio_ata(struct pci_device *pci, int chanid, int slave)
 {
     if (!csm_boot_table)
@@ -327,7 +344,7 @@ int csm_bootprio_ata(struct pci_device *pci, int chanid, int slave)
     int index = 1 + (chanid * 2) + slave;
     dprintf(3, "CSM bootprio for ATA%d,%d (index %d) is %d\n", chanid, slave,
             index, bbs[index].BootPriority);
-    return bbs[index].BootPriority;
+    return csm_prio_to_seabios(bbs[index].BootPriority);
 }
 
 int csm_bootprio_fdc(struct pci_device *pci, int port, int fdid)
@@ -336,7 +353,7 @@ int csm_bootprio_fdc(struct pci_device *pci, int port, int fdid)
         return -1;
     BBS_TABLE *bbs = (void *)csm_boot_table->BbsTable;
     dprintf(3, "CSM bootprio for FDC is %d\n", bbs[0].BootPriority);
-    return bbs[0].BootPriority;
+    return csm_prio_to_seabios(bbs[0].BootPriority);
 }
 
 int csm_bootprio_pci(struct pci_device *pci)
@@ -350,7 +367,7 @@ int csm_bootprio_pci(struct pci_device *pci)
         if (pci->bdf == pci_to_bdf(bbs[i].Bus, bbs[i].Device, bbs[i].Function)) {
             dprintf(3, "CSM bootprio for PCI(%d,%d,%d) is %d\n", bbs[i].Bus,
                     bbs[i].Device, bbs[i].Function, bbs[i].BootPriority);
-            return bbs[i].BootPriority;
+            return csm_prio_to_seabios(bbs[i].BootPriority);
         }
     }
     return -1;