savagefb: VGA state save and restore

Allow the saving and restoration of VGA text mode.  The state is saved on the
first open and restored on the last close. Because of the VGA registers are
linearly mapped to the MMIO space, MMIO access is used which is not limited to
X86 platforms nor to the primary display device.

An echo 0 > /sys/class/vtconsole/vtcon1/bind will convert the display from
graphics to text mode.

Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 39 insertions, 0 deletions

diff --git a/drivers/video/savage/savagefb_driver.c b/drivers/video/savage/savagefb_driver.c
index 0166ec2ccf32..3d7507ad55f6 100644
--- a/drivers/video/savage/savagefb_driver.c
+++ b/drivers/video/savage/savagefb_driver.c
@@ -1623,8 +1623,46 @@ static void savagefb_restore_state(struct fb_info *info)
         savagefb_blank(FB_BLANK_UNBLANK, info);
 }
 
+static int savagefb_open(struct fb_info *info, int user)
+{
+        struct savagefb_par *par = info->par;
+
+        mutex_lock(&par->open_lock);
+
+        if (!par->open_count) {
+                memset(&par->vgastate, 0, sizeof(par->vgastate));
+                par->vgastate.flags = VGA_SAVE_CMAP | VGA_SAVE_FONTS |
+                        VGA_SAVE_MODE;
+                par->vgastate.vgabase = par->mmio.vbase + 0x8000;
+                save_vga(&par->vgastate);
+                savage_get_default_par(par, &par->initial);
+        }
+
+        par->open_count++;
+        mutex_unlock(&par->open_lock);
+        return 0;
+}
+
+static int savagefb_release(struct fb_info *info, int user)
+{
+        struct savagefb_par *par = info->par;
+
+        mutex_lock(&par->open_lock);
+
+        if (par->open_count == 1) {
+                savage_set_default_par(par, &par->initial);
+                restore_vga(&par->vgastate);
+        }
+
+        par->open_count--;
+        mutex_unlock(&par->open_lock);
+        return 0;
+}
+
 static struct fb_ops savagefb_ops = {
         .owner          = THIS_MODULE,
+        .fb_open        = savagefb_open,
+        .fb_release     = savagefb_release,
         .fb_check_var   = savagefb_check_var,
         .fb_set_par     = savagefb_set_par,
         .fb_setcolreg   = savagefb_setcolreg,
@@ -2173,6 +2211,7 @@ static int __devinit savagefb_probe(struct pci_dev* dev,
         if (!info)
                 return -ENOMEM;
         par = info->par;
+        mutex_init(&par->open_lock);
         err = pci_enable_device(dev);
         if (err)
                 goto failed_enable;