Preliminary DISPI VBE driver implementation

It allowed me to boot Windows 7 with Qemu BOCHS VGA emulation and it
seemed to work fine. It probably needs some further testing though.

Signed-off-by: Julian Pidancet <julian.pidancet@gmail.com>
diff --git a/vgasrc/dispi.h b/vgasrc/dispi.h
new file mode 100644
index 0000000..963cb13
--- /dev/null
+++ b/vgasrc/dispi.h
@@ -0,0 +1,55 @@
+#ifndef __DISPI_H
+#define __DISPI_H
+
+#include "types.h" // u8
+#include "ioport.h" // outb
+
+#define VBE_DISPI_BANK_ADDRESS           0xA0000
+#define VBE_DISPI_BANK_SIZE_KB           64
+
+#define VBE_DISPI_MAX_XRES               2560
+#define VBE_DISPI_MAX_YRES               1600
+
+#define VBE_DISPI_IOPORT_INDEX           0x01CE
+#define VBE_DISPI_IOPORT_DATA            0x01CF
+
+#define VBE_DISPI_INDEX_ID               0x0
+#define VBE_DISPI_INDEX_XRES             0x1
+#define VBE_DISPI_INDEX_YRES             0x2
+#define VBE_DISPI_INDEX_BPP              0x3
+#define VBE_DISPI_INDEX_ENABLE           0x4
+#define VBE_DISPI_INDEX_BANK             0x5
+#define VBE_DISPI_INDEX_VIRT_WIDTH       0x6
+#define VBE_DISPI_INDEX_VIRT_HEIGHT      0x7
+#define VBE_DISPI_INDEX_X_OFFSET         0x8
+#define VBE_DISPI_INDEX_Y_OFFSET         0x9
+#define VBE_DISPI_INDEX_VIDEO_MEMORY_64K 0xa
+
+#define VBE_DISPI_ID0                    0xB0C0
+#define VBE_DISPI_ID1                    0xB0C1
+#define VBE_DISPI_ID2                    0xB0C2
+#define VBE_DISPI_ID3                    0xB0C3
+#define VBE_DISPI_ID4                    0xB0C4
+#define VBE_DISPI_ID5                    0xB0C5
+
+#define VBE_DISPI_DISABLED               0x00
+#define VBE_DISPI_ENABLED                0x01
+#define VBE_DISPI_GETCAPS                0x02
+#define VBE_DISPI_8BIT_DAC               0x20
+#define VBE_DISPI_LFB_ENABLED            0x40
+#define VBE_DISPI_NOCLEARMEM             0x80
+
+#define VBE_DISPI_LFB_PHYSICAL_ADDRESS   0xE0000000
+
+static inline u16 dispi_read(u16 reg)
+{
+    outw(reg, VBE_DISPI_IOPORT_INDEX);
+    return inw(VBE_DISPI_IOPORT_DATA);
+}
+static inline void dispi_write(u16 reg, u16 val)
+{
+    outw(reg, VBE_DISPI_IOPORT_INDEX);
+    outw(val, VBE_DISPI_IOPORT_DATA);
+}
+
+#endif
diff --git a/vgasrc/vbe.c b/vgasrc/vbe.c
index b6e0037..2a1e932 100644
--- a/vgasrc/vbe.c
+++ b/vgasrc/vbe.c
@@ -1,5 +1,9 @@
 #include "vgatables.h"
 #include "vbe.h"
+#include "dispi.h"
+#include "util.h"
+#include "config.h" // CONFIG_
+#include "biosvar.h" // SET_BDA
 
 struct mode
 {
@@ -74,23 +78,131 @@
     { 0, },
 };
 
+#define BYTES_PER_PIXEL(m) ((GET_GLOBAL((m)->depth) + 7) / 8)
+
+u32 pci_lfb_addr VAR16;
+
+static inline u32 pci_config_readl(u8 bus, u8 devfn, u16 addr)
+{
+    int status;
+    u32 val;
+    u16 bdf = (bus << 16) | devfn;
+
+    addr &= ~3;
+
+    asm volatile(
+            "int $0x1a\n"
+            "cli\n"
+            "cld"
+            : "=a"(status), "=c"(val)
+            : "a"(0xb10a), "b"(bdf), "D"(addr)
+            : "cc", "memory");
+
+    if ((status >> 16))
+        return (u32)-1;
+
+    return val;
+}
+
+
+static u16 dispi_get_max_xres(void)
+{
+    u16 en;
+    u16 xres;
+
+    en = dispi_read(VBE_DISPI_INDEX_ENABLE);
+
+    dispi_write(VBE_DISPI_INDEX_ENABLE, en | VBE_DISPI_GETCAPS);
+    xres = dispi_read(VBE_DISPI_INDEX_XRES);
+    dispi_write(VBE_DISPI_INDEX_ENABLE, en);
+
+    return xres;
+}
+
+static u16 dispi_get_max_bpp(void)
+{
+    u16 en;
+    u16 bpp;
+
+    en = dispi_read(VBE_DISPI_INDEX_ENABLE);
+
+    dispi_write(VBE_DISPI_INDEX_ENABLE, en | VBE_DISPI_GETCAPS);
+    bpp = dispi_read(VBE_DISPI_INDEX_BPP);
+    dispi_write(VBE_DISPI_INDEX_ENABLE, en);
+
+    return bpp;
+}
+
 /* Called only during POST */
 int
 vbe_init(u8 bus, u8 devfn)
 {
-    return -1;
+    u32 lfb_addr;
+
+    if (!CONFIG_VGA_BOCHS)
+        return -1;
+
+    /* Sanity checks */
+    dispi_write(VBE_DISPI_INDEX_ID, VBE_DISPI_ID0);
+    if (dispi_read(VBE_DISPI_INDEX_ID) != VBE_DISPI_ID0) {
+        dprintf(1, "No VBE DISPI interface detected\n");
+        return -1;
+    }
+
+    SET_BDA(vbe_flag, 0x1);
+    dispi_write(VBE_DISPI_INDEX_ID, VBE_DISPI_ID5);
+
+    if (CONFIG_VGA_PCI)
+        lfb_addr = pci_config_readl(bus, devfn, 0x10) & ~0xf;
+    else
+        lfb_addr = VBE_DISPI_LFB_PHYSICAL_ADDRESS;
+
+    SET_FARVAR(get_global_seg(), pci_lfb_addr, lfb_addr);
+
+    dprintf(1, "VBE DISPI detected. lfb_addr=%x\n", GET_GLOBAL(pci_lfb_addr));
+
+    return 0;
 }
 
 int
 vbe_enabled(void)
 {
-    return 0;
+    return GET_BDA(vbe_flag);
 }
 
 u16
 vbe_total_mem(void)
 {
-    return 0;
+    return dispi_read(VBE_DISPI_INDEX_VIDEO_MEMORY_64K);
+}
+
+static struct mode *find_mode_entry(u16 mode)
+{
+    struct mode *m;
+
+    for (m = vbe_modes; GET_GLOBAL(m->mode); m++) {
+        if (GET_GLOBAL(m->mode) == mode)
+            return m;
+    }
+
+    return NULL;
+}
+
+static int mode_valid(struct mode *m)
+{
+    u16 max_xres = dispi_get_max_xres();
+    u16 max_bpp = dispi_get_max_bpp();
+    u32 max_mem = vbe_total_mem() * 64 * 1024;
+
+    u32 mem = GET_GLOBAL(m->width) * GET_GLOBAL(m->height) *
+              BYTES_PER_PIXEL(m);
+
+    if (GET_GLOBAL(m->width) > max_xres ||
+        GET_GLOBAL(m->depth) > max_bpp ||
+        mem > max_mem)
+        return 0;
+
+    return 1;
 }
 
 int
@@ -98,6 +210,17 @@
 {
     int count = 0;
     u16 *dest = (u16 *)(u32)ptr;
+    struct mode *m;
+
+    for (m = vbe_modes; GET_GLOBAL(m->mode); m++) {
+        if (!mode_valid(m))
+            continue;
+
+        dprintf(1, "VBE found mode %x valid.\n", GET_GLOBAL(m->mode));
+        SET_FARVAR(seg, dest[count], GET_GLOBAL(m->mode));
+
+        count++;
+    }
 
     SET_FARVAR(seg, dest[count], 0xffff); /* End of list */
 
@@ -107,36 +230,111 @@
 int
 vbe_mode_info(u16 mode, struct vbe_modeinfo *info)
 {
-    return -1;
+    struct mode *m;
+
+    m = find_mode_entry(mode);
+    if (!m || !mode_valid(m))
+        return -1;
+
+    info->width = GET_GLOBAL(m->width);
+    info->height = GET_GLOBAL(m->height);
+    info->depth = GET_GLOBAL(m->depth);
+
+    info->linesize = info->width * ((info->depth + 7) / 8);
+    info->phys_base = GET_GLOBAL(pci_lfb_addr);
+    info->vram_size = vbe_total_mem() * 64 * 1024;
+
+    return 0;
 }
 
 void
 vbe_hires_enable(int enable)
 {
+    u16 flags = enable ?
+        VBE_DISPI_ENABLED |
+        VBE_DISPI_LFB_ENABLED |
+        VBE_DISPI_NOCLEARMEM : 0;
 
+    dispi_write(VBE_DISPI_INDEX_ENABLE, flags);
 }
 
 void
 vbe_set_mode(u16 mode, struct vbe_modeinfo *info)
 {
+    if (info->depth == 4)
+        vga_set_mode(0x6a, 0);
+    if (info->depth == 8)
+        // XXX load_dac_palette(3);
+        ;
 
+    dispi_write(VBE_DISPI_INDEX_BPP, info->depth);
+    dispi_write(VBE_DISPI_INDEX_XRES, info->width);
+    dispi_write(VBE_DISPI_INDEX_YRES, info->height);
+    dispi_write(VBE_DISPI_INDEX_BANK, 0);
+
+    /* VGA compat setup */
+    //XXX: This probably needs some reverse engineering
+    u8 v;
+    outw(0x0011, VGAREG_VGA_CRTC_ADDRESS);
+    outw(((info->width * 4 - 1) << 8) | 0x1, VGAREG_VGA_CRTC_ADDRESS);
+    dispi_write(VBE_DISPI_INDEX_VIRT_WIDTH, info->width);
+    outw(((info->height - 1) << 8) | 0x12, VGAREG_VGA_CRTC_ADDRESS);
+    outw(((info->height - 1) & 0xff00) | 0x7, VGAREG_VGA_CRTC_ADDRESS);
+    v = inb(VGAREG_VGA_CRTC_DATA) & 0xbd;
+    if (v & 0x1)
+        v |= 0x2;
+    if (v & 0x2)
+        v |= 0x40;
+    outb(v, VGAREG_VGA_CRTC_DATA);
+
+    outw(0x9, VGAREG_VGA_CRTC_ADDRESS);
+    outb(0x17, VGAREG_VGA_CRTC_ADDRESS);
+    outb(inb(VGAREG_VGA_CRTC_DATA) | 0x3, VGAREG_VGA_CRTC_DATA);
+    v = inb(VGAREG_ACTL_RESET);
+    outw(0x10, VGAREG_ACTL_ADDRESS);
+    v = inb(VGAREG_ACTL_READ_DATA) | 0x1;
+    outb(v, VGAREG_ACTL_ADDRESS);
+    outb(0x20, VGAREG_ACTL_ADDRESS);
+    outw(0x0506, VGAREG_GRDC_ADDRESS);
+    outw(0x0f02, VGAREG_SEQU_ADDRESS);
+    if (info->depth >= 8) {
+        outb(0x14, VGAREG_VGA_CRTC_ADDRESS);
+        outb(inb(VGAREG_VGA_CRTC_DATA) | 0x40, VGAREG_VGA_CRTC_DATA);
+        v = inb(VGAREG_ACTL_RESET);
+        outw(0x10, VGAREG_ACTL_ADDRESS);
+        v = inb(VGAREG_ACTL_READ_DATA) | 0x40;
+        outb(v, VGAREG_ACTL_ADDRESS);
+        outb(0x20, VGAREG_ACTL_ADDRESS);
+        outb(0x04, VGAREG_SEQU_ADDRESS);
+        v = inb(VGAREG_SEQU_DATA) | 0x08;
+        outb(v, VGAREG_SEQU_DATA);
+        outb(0x05, VGAREG_GRDC_ADDRESS);
+        v = inb(VGAREG_GRDC_DATA) & 0x9f;
+        outb(v | 0x40, VGAREG_GRDC_DATA);
+    }
+
+    SET_BDA(vbe_mode, mode);
 }
 
 void
 vbe_clear_scr(void)
 {
+    u16 en;
 
+    en = dispi_read(VBE_DISPI_INDEX_ENABLE);
+    en &= ~VBE_DISPI_NOCLEARMEM;
+    dispi_write(VBE_DISPI_INDEX_ENABLE, en);
 }
 
 int
 vbe_hires_enabled(void)
 {
-    return 0;
+    return dispi_read(VBE_DISPI_INDEX_ENABLE) & VBE_DISPI_ENABLED;
 }
 
 u16
 vbe_curr_mode(void)
 {
-    return 0;
+    return GET_BDA(vbe_mode);
 }