Initial PnP bios call support.

This commit provides just enough PnP support for gPXE to not hook int19.

1 files changed, 105 insertions, 0 deletions

diff --git a/src/pnpbios.c b/src/pnpbios.c
new file mode 100644
index 0000000..6f36a4a
--- /dev/null
+++ b/src/pnpbios.c
@@ -0,0 +1,105 @@
+// PNP BIOS calls
+//
+// Copyright (C) 2008  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "util.h" // checksum
+#include "config.h" // BUILD_BIOS_ADDR
+#include "farptr.h" // SET_FARVAR
+
+struct pnpheader {
+    u32 signature;
+    u8 version;
+    u8 length;
+    u16 control;
+    u8 checksum;
+    u32 eventloc;
+    u16 real_ip;
+    u16 real_cs;
+    u16 prot_ip;
+    u32 prot_base;
+    u32 oemid;
+    u16 real_ds;
+    u32 prot_database;
+} PACKED;
+
+extern struct pnpheader PNPHEADER;
+extern const char pnp_string[];
+
+#if MODE16
+# if CONFIG_PNPBIOS
+struct pnpheader PNPHEADER __aligned(16) VISIBLE16 = {
+    .signature = PNP_SIGNATURE,
+    .version = 0x10,
+    .length = sizeof(PNPHEADER),
+    .real_cs = SEG_BIOS,
+    .prot_base = BUILD_BIOS_ADDR,
+    .real_ds = SEG_BIOS,
+    .prot_database = BUILD_BIOS_ADDR,
+};
+# else
+// We need a copy of this string in the 0xf000 segment, but we are not
+// actually a PnP BIOS, so make sure it is *not* aligned, so OSes will
+// not see it if they scan.
+const char pnp_string[] __aligned(2) VISIBLE16 = " $PnP";
+# endif
+#endif
+
+#define FUNCTION_NOT_SUPPORTED 0x82
+
+// BBS - Get Version and Installation Check
+static u16
+handle_pnp60(u16 *args)
+{
+    u16 version_ptr = args[1];
+    u16 version_seg = args[2];
+    SET_FARVAR(version_seg, *(u16*)(version_ptr+0), 0x0101);
+    return 0;
+}
+
+static u16
+handle_pnpXX(u16 *args)
+{
+    return FUNCTION_NOT_SUPPORTED;
+}
+
+u16 VISIBLE16
+handle_pnp(u16 *args)
+{
+    if (! CONFIG_PNPBIOS)
+        return FUNCTION_NOT_SUPPORTED;
+
+    u16 arg1 = args[0];
+    dprintf(DEBUG_HDL_pnp, "pnp call arg1=%x\n", arg1);
+
+    switch (arg1) {
+    case 0x60: return handle_pnp60(args);
+    default:   return handle_pnpXX(args);
+    }
+}
+
+u16
+get_pnp_offset()
+{
+    if (! CONFIG_PNPBIOS)
+        return (u32)pnp_string + 1 - BUILD_BIOS_ADDR;
+    return (u32)&PNPHEADER - BUILD_BIOS_ADDR;
+}
+
+// romlayout.S
+extern void entry_pnp_real();
+extern void entry_pnp_prot();
+
+void
+pnp_setup()
+{
+    if (! CONFIG_PNPBIOS)
+        return;
+
+    dprintf(3, "init PNPBIOS table\n");
+
+    PNPHEADER.real_ip = (u32)entry_pnp_real - BUILD_BIOS_ADDR;
+    PNPHEADER.prot_ip = (u32)entry_pnp_prot - BUILD_BIOS_ADDR;
+    PNPHEADER.checksum = -checksum((u8*)&PNPHEADER, sizeof(PNPHEADER));
+}