PPC: mac_nvram: Split NVRAM into OF and OSX parts

Mac OS X (at least with -M mac99) searches for a valid NVRAM partition
of a special Apple type. If it can't find that partition in the first
half of NVRAM, it will look at the second half.

There are a few implications from this. The first is that we need to
split NVRAM into 2 halves - one for Open Firmware use, the other one for
Mac OS X. Without this split Mac OS X will just loop endlessly over the
second half trying to find a partition.

The other implication is that we should provide a specially crafted Mac
OS X compatible NVRAM partition on the second half that Mac OS X can
happily use as it sees fit.

Signed-off-by: Alexander Graf <agraf@suse.de>

hw/nvram/mac_nvram.c

@@ -26,6 +26,7 @@
 #include "hw/nvram/openbios_firmware_abi.h"
 #include "sysemu/sysemu.h"
 #include "hw/ppc/mac.h"
+#include <zlib.h>
 
 /* debug NVR */
 //#define DEBUG_NVR
@@ -137,15 +138,16 @@ static void macio_nvram_register_types(void)
 }
 
 /* Set up a system OpenBIOS NVRAM partition */
-void pmac_format_nvram_partition (MacIONVRAMState *nvr, int len)
+static void pmac_format_nvram_partition_of(MacIONVRAMState *nvr, int off,
+                                           int len)
 {
     unsigned int i;
-    uint32_t start = 0, end;
+    uint32_t start = off, end;
     struct OpenBIOS_nvpart_v1 *part_header;
 
     // OpenBIOS nvram variables
     // Variable partition
-    part_header = (struct OpenBIOS_nvpart_v1 *)nvr->data;
+    part_header = (struct OpenBIOS_nvpart_v1 *)&nvr->data[start];
     part_header->signature = OPENBIOS_PART_SYSTEM;
     pstrcpy(part_header->name, sizeof(part_header->name), "system");
 
@@ -173,4 +175,39 @@ void pmac_format_nvram_partition (MacIONVRAMState *nvr, int len)
     OpenBIOS_finish_partition(part_header, end - start);
 }
 
+#define OSX_NVRAM_SIGNATURE     (0x5A)
+
+/* Set up a Mac OS X NVRAM partition */
+static void pmac_format_nvram_partition_osx(MacIONVRAMState *nvr, int off,
+                                            int len)
+{
+    uint32_t start = off;
+    struct OpenBIOS_nvpart_v1 *part_header;
+    unsigned char *data = &nvr->data[start];
+
+    /* empty partition */
+    part_header = (struct OpenBIOS_nvpart_v1 *)data;
+    part_header->signature = OSX_NVRAM_SIGNATURE;
+    pstrcpy(part_header->name, sizeof(part_header->name), "wwwwwwwwwwww");
+
+    OpenBIOS_finish_partition(part_header, len);
+
+    /* Generation */
+    stl_be_p(&data[20], 2);
+
+    /* Adler32 checksum */
+    stl_be_p(&data[16], adler32(0, &data[20], len - 20));
+}
+
+/* Set up NVRAM with OF and OSX partitions */
+void pmac_format_nvram_partition(MacIONVRAMState *nvr, int len)
+{
+    /*
+     * Mac OS X expects side "B" of the flash at the second half of NVRAM,
+     * so we use half of the chip for OF and the other half for a free OSX
+     * partition.
+     */
+    pmac_format_nvram_partition_of(nvr, 0, len / 2);
+    pmac_format_nvram_partition_osx(nvr, len / 2, len / 2);
+}
 type_init(macio_nvram_register_types)