vga: add mmio bar to standard vga

This patch adds a mmio bar to the qemu standard vga which allows to
access the standard vga registers and bochs dispi interface registers
via mmio.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

4 files changed, 121 insertions, 3 deletions

diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 82364ab0d5..5bd4572d47 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -379,6 +379,10 @@ static QEMUMachine pc_machine_v1_3 = {
             .driver   = "qxl-vga",\
             .property = "revision",\
             .value    = stringify(3),\
+        },{\
+            .driver   = "VGA",\
+            .property = "mmio",\
+            .value    = "off",\
         }
 
 static QEMUMachine pc_machine_v1_2 = {
diff --git a/hw/vga-pci.c b/hw/vga-pci.c
index 5f55f361a2..f7d0256e87 100644
--- a/hw/vga-pci.c
+++ b/hw/vga-pci.c
@@ -29,9 +29,23 @@
 #include "qemu-timer.h"
 #include "loader.h"
 
+#define PCI_VGA_IOPORT_OFFSET 0x400
+#define PCI_VGA_IOPORT_SIZE   (0x3e0 - 0x3c0)
+#define PCI_VGA_BOCHS_OFFSET  0x500
+#define PCI_VGA_BOCHS_SIZE    (0x0b * 2)
+#define PCI_VGA_MMIO_SIZE     0x1000
+
+enum vga_pci_flags {
+    PCI_VGA_FLAG_ENABLE_MMIO = 1,
+};
+
 typedef struct PCIVGAState {
     PCIDevice dev;
     VGACommonState vga;
+    uint32_t flags;
+    MemoryRegion mmio;
+    MemoryRegion ioport;
+    MemoryRegion bochs;
 } PCIVGAState;
 
 static const VMStateDescription vmstate_vga_pci = {
@@ -46,6 +60,84 @@ static const VMStateDescription vmstate_vga_pci = {
     }
 };
 
+static uint64_t pci_vga_ioport_read(void *ptr, target_phys_addr_t addr,
+                                    unsigned size)
+{
+    PCIVGAState *d = ptr;
+    uint64_t ret = 0;
+
+    switch (size) {
+    case 1:
+        ret = vga_ioport_read(&d->vga, addr);
+        break;
+    case 2:
+        ret  = vga_ioport_read(&d->vga, addr);
+        ret |= vga_ioport_read(&d->vga, addr+1) << 8;
+        break;
+    }
+    return ret;
+}
+
+static void pci_vga_ioport_write(void *ptr, target_phys_addr_t addr,
+                                 uint64_t val, unsigned size)
+{
+    PCIVGAState *d = ptr;
+    switch (size) {
+    case 1:
+        vga_ioport_write(&d->vga, addr, val);
+        break;
+    case 2:
+        /*
+         * Update bytes in little endian order.  Allows to update
+         * indexed registers with a single word write because the
+         * index byte is updated first.
+         */
+        vga_ioport_write(&d->vga, addr, val & 0xff);
+        vga_ioport_write(&d->vga, addr+1, (val >> 8) & 0xff);
+        break;
+    }
+}
+
+static const MemoryRegionOps pci_vga_ioport_ops = {
+    .read = pci_vga_ioport_read,
+    .write = pci_vga_ioport_write,
+    .valid.min_access_size = 1,
+    .valid.max_access_size = 4,
+    .impl.min_access_size = 1,
+    .impl.max_access_size = 2,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
+static uint64_t pci_vga_bochs_read(void *ptr, target_phys_addr_t addr,
+                                   unsigned size)
+{
+    PCIVGAState *d = ptr;
+    int index = addr >> 1;
+
+    vbe_ioport_write_index(&d->vga, 0, index);
+    return vbe_ioport_read_data(&d->vga, 0);
+}
+
+static void pci_vga_bochs_write(void *ptr, target_phys_addr_t addr,
+                                uint64_t val, unsigned size)
+{
+    PCIVGAState *d = ptr;
+    int index = addr >> 1;
+
+    vbe_ioport_write_index(&d->vga, 0, index);
+    vbe_ioport_write_data(&d->vga, 0, val);
+}
+
+static const MemoryRegionOps pci_vga_bochs_ops = {
+    .read = pci_vga_bochs_read,
+    .write = pci_vga_bochs_write,
+    .valid.min_access_size = 1,
+    .valid.max_access_size = 4,
+    .impl.min_access_size = 2,
+    .impl.max_access_size = 2,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
 static int pci_std_vga_initfn(PCIDevice *dev)
 {
     PCIVGAState *d = DO_UPCAST(PCIVGAState, dev, dev);
@@ -61,6 +153,21 @@ static int pci_std_vga_initfn(PCIDevice *dev)
     /* XXX: VGA_RAM_SIZE must be a power of two */
     pci_register_bar(&d->dev, 0, PCI_BASE_ADDRESS_MEM_PREFETCH, &s->vram);
 
+    /* mmio bar for vga register access */
+    if (d->flags & (1 << PCI_VGA_FLAG_ENABLE_MMIO)) {
+        memory_region_init(&d->mmio, "vga.mmio", 4096);
+        memory_region_init_io(&d->ioport, &pci_vga_ioport_ops, d,
+                              "vga ioports remapped", PCI_VGA_IOPORT_SIZE);
+        memory_region_init_io(&d->bochs, &pci_vga_bochs_ops, d,
+                              "bochs dispi interface", PCI_VGA_BOCHS_SIZE);
+
+        memory_region_add_subregion(&d->mmio, PCI_VGA_IOPORT_OFFSET,
+                                    &d->ioport);
+        memory_region_add_subregion(&d->mmio, PCI_VGA_BOCHS_OFFSET,
+                                    &d->bochs);
+        pci_register_bar(&d->dev, 2, PCI_BASE_ADDRESS_SPACE_MEMORY, &d->mmio);
+    }
+
     if (!dev->rom_bar) {
         /* compatibility with pc-0.13 and older */
         vga_init_vbe(s, pci_address_space(dev));
@@ -71,6 +178,7 @@ static int pci_std_vga_initfn(PCIDevice *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_END_OF_LIST(),
 };
 
diff --git a/hw/vga.c b/hw/vga.c
index afaef0d711..6afe48ce58 100644
--- a/hw/vga.c
+++ b/hw/vga.c
@@ -591,7 +591,7 @@ static uint32_t vbe_ioport_read_index(void *opaque, uint32_t addr)
     return val;
 }
 
-static uint32_t vbe_ioport_read_data(void *opaque, uint32_t addr)
+uint32_t vbe_ioport_read_data(void *opaque, uint32_t addr)
 {
     VGACommonState *s = opaque;
     uint32_t val;
@@ -627,13 +627,13 @@ static uint32_t vbe_ioport_read_data(void *opaque, uint32_t addr)
     return val;
 }
 
-static void vbe_ioport_write_index(void *opaque, uint32_t addr, uint32_t val)
+void vbe_ioport_write_index(void *opaque, uint32_t addr, uint32_t val)
 {
     VGACommonState *s = opaque;
     s->vbe_index = val;
 }
 
-static void vbe_ioport_write_data(void *opaque, uint32_t addr, uint32_t val)
+void vbe_ioport_write_data(void *opaque, uint32_t addr, uint32_t val)
 {
     VGACommonState *s = opaque;
 
diff --git a/hw/vga_int.h b/hw/vga_int.h
index 330a32f77d..5b68490301 100644
--- a/hw/vga_int.h
+++ b/hw/vga_int.h
@@ -208,7 +208,13 @@ void vga_invalidate_scanlines(VGACommonState *s, int y1, int y2);
 void ppm_save(const char *filename, struct DisplaySurface *ds, Error **errp);
 
 int vga_ioport_invalid(VGACommonState *s, uint32_t addr);
+
+#ifdef CONFIG_BOCHS_VBE
 void vga_init_vbe(VGACommonState *s, MemoryRegion *address_space);
+uint32_t vbe_ioport_read_data(void *opaque, uint32_t addr);
+void vbe_ioport_write_index(void *opaque, uint32_t addr, uint32_t val);
+void vbe_ioport_write_data(void *opaque, uint32_t addr, uint32_t val);
+#endif
 
 extern const uint8_t sr_mask[8];
 extern const uint8_t gr_mask[16];