vga-pci: add qext region to mmio

Add a qemu extented register range to the standard vga mmio bar.
Right nowe there are two registers:  One readonly register returning the
size of the region (so we can easily add more registers there if needed)
and one endian control register, so guests (especially ppc) can flip
the framebuffer endianness as they need it.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 70 insertions, 0 deletions

diff --git a/hw/display/vga-pci.c b/hw/display/vga-pci.c
index 0351d94..db922f1 100644
--- a/hw/display/vga-pci.c
+++ b/hw/display/vga-pci.c
@@ -35,10 +35,18 @@
 #define PCI_VGA_IOPORT_SIZE   (0x3e0 - 0x3c0)
 #define PCI_VGA_BOCHS_OFFSET  0x500
 #define PCI_VGA_BOCHS_SIZE    (0x0b * 2)
+#define PCI_VGA_QEXT_OFFSET   0x600
+#define PCI_VGA_QEXT_SIZE     (2 * 4)
 #define PCI_VGA_MMIO_SIZE     0x1000
 
+#define PCI_VGA_QEXT_REG_SIZE         (0 * 4)
+#define PCI_VGA_QEXT_REG_BYTEORDER    (1 * 4)
+#define  PCI_VGA_QEXT_LITTLE_ENDIAN   0x1e1e1e1e
+#define  PCI_VGA_QEXT_BIG_ENDIAN      0xbebebebe
+
 enum vga_pci_flags {
     PCI_VGA_FLAG_ENABLE_MMIO = 1,
+    PCI_VGA_FLAG_ENABLE_QEXT = 2,
 };
 
 typedef struct PCIVGAState {
@@ -48,6 +56,7 @@ typedef struct PCIVGAState {
     MemoryRegion mmio;
     MemoryRegion ioport;
     MemoryRegion bochs;
+    MemoryRegion qext;
 } PCIVGAState;
 
 static const VMStateDescription vmstate_vga_pci = {
@@ -140,6 +149,46 @@ static const MemoryRegionOps pci_vga_bochs_ops = {
     .endianness = DEVICE_LITTLE_ENDIAN,
 };
 
+static uint64_t pci_vga_qext_read(void *ptr, hwaddr addr, unsigned size)
+{
+    PCIVGAState *d = ptr;
+
+    switch (addr) {
+    case PCI_VGA_QEXT_REG_SIZE:
+        return PCI_VGA_QEXT_SIZE;
+    case PCI_VGA_QEXT_REG_BYTEORDER:
+        return d->vga.big_endian_fb ?
+            PCI_VGA_QEXT_BIG_ENDIAN : PCI_VGA_QEXT_LITTLE_ENDIAN;
+    default:
+        return 0;
+    }
+}
+
+static void pci_vga_qext_write(void *ptr, hwaddr addr,
+                               uint64_t val, unsigned size)
+{
+    PCIVGAState *d = ptr;
+
+    switch (addr) {
+    case PCI_VGA_QEXT_REG_BYTEORDER:
+        if (val == PCI_VGA_QEXT_BIG_ENDIAN) {
+            d->vga.big_endian_fb = true;
+        }
+        if (val == PCI_VGA_QEXT_LITTLE_ENDIAN) {
+            d->vga.big_endian_fb = false;
+        }
+        break;
+    }
+}
+
+static const MemoryRegionOps pci_vga_qext_ops = {
+    .read = pci_vga_qext_read,
+    .write = pci_vga_qext_write,
+    .valid.min_access_size = 4,
+    .valid.max_access_size = 4,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
 static int pci_std_vga_initfn(PCIDevice *dev)
 {
     PCIVGAState *d = DO_UPCAST(PCIVGAState, dev, dev);
@@ -167,6 +216,15 @@ static int pci_std_vga_initfn(PCIDevice *dev)
                                     &d->ioport);
         memory_region_add_subregion(&d->mmio, PCI_VGA_BOCHS_OFFSET,
                                     &d->bochs);
+
+        if (d->flags & (1 << PCI_VGA_FLAG_ENABLE_QEXT)) {
+            memory_region_init_io(&d->qext, NULL, &pci_vga_qext_ops, d,
+                                  "qemu extended regs", PCI_VGA_QEXT_SIZE);
+            memory_region_add_subregion(&d->mmio, PCI_VGA_QEXT_OFFSET,
+                                        &d->qext);
+            pci_set_byte(&d->dev.config[PCI_REVISION_ID], 2);
+        }
+
         pci_register_bar(&d->dev, 2, PCI_BASE_ADDRESS_SPACE_MEMORY, &d->mmio);
     }
 
@@ -199,6 +257,14 @@ static int pci_secondary_vga_initfn(PCIDevice *dev)
     memory_region_add_subregion(&d->mmio, PCI_VGA_BOCHS_OFFSET,
                                 &d->bochs);
 
+    if (d->flags & (1 << PCI_VGA_FLAG_ENABLE_QEXT)) {
+        memory_region_init_io(&d->qext, NULL, &pci_vga_qext_ops, d,
+                              "qemu extended regs", PCI_VGA_QEXT_SIZE);
+        memory_region_add_subregion(&d->mmio, PCI_VGA_QEXT_OFFSET,
+                                    &d->qext);
+        pci_set_byte(&d->dev.config[PCI_REVISION_ID], 2);
+    }
+
     pci_register_bar(&d->dev, 0, PCI_BASE_ADDRESS_MEM_PREFETCH, &s->vram);
     pci_register_bar(&d->dev, 2, PCI_BASE_ADDRESS_SPACE_MEMORY, &d->mmio);
 
@@ -215,11 +281,15 @@ static void pci_secondary_vga_reset(DeviceState *dev)
 static Property vga_pci_properties[] = {
     DEFINE_PROP_UINT32("vgamem_mb", PCIVGAState, vga.vram_size_mb, 16),
     DEFINE_PROP_BIT("mmio", PCIVGAState, flags, PCI_VGA_FLAG_ENABLE_MMIO, true),
+    DEFINE_PROP_BIT("qemu-extended-regs",
+                    PCIVGAState, flags, PCI_VGA_FLAG_ENABLE_QEXT, true),
     DEFINE_PROP_END_OF_LIST(),
 };
 
 static Property secondary_pci_properties[] = {
     DEFINE_PROP_UINT32("vgamem_mb", PCIVGAState, vga.vram_size_mb, 16),
+    DEFINE_PROP_BIT("qemu-extended-regs",
+                    PCIVGAState, flags, PCI_VGA_FLAG_ENABLE_QEXT, true),
     DEFINE_PROP_END_OF_LIST(),
 };