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Subject[PATCH 1/3: FBDEV: VGA State Save/Restore module
From
Date
Hi,

Attached is a patch against linux-2.5.50 + James Simmons fbdev.diff to
save and restore the VGA state. This includes character maps (plane
0-3), the colormap, and the video mode. This can be used in fb_open()
and fb_release() to go back to VGA text/graphics mode.

Usage:

struct fb_vgastate state;

/* To save VGA state */
state.flags = VGA_SAVE_MODE | VGA_SAVE_CMAP | VGA_SAVE_FONTS;
fb_save_vga(&state);

/* To restore VGA state */
fb_restore_vga(&state);

Limitations:
1. Restoring the VGA state from high-resolution graphics mode may
result in a corrupt display which can be corrected by switching
consoles. May need a screen redraw at this point. Restoring from VGA
graphics mode to text mode and vice versa is okay.

2. Assumes some things about the hardware which is not universally
correct: VGA memory base is at 0xA0000, memory size is 64KB, the
hardware palette is readable, etc.

Any comments welcome.

Tony

PS: Please reverse the early patch I submitted if it was applied --
vgastate.diff




diff -Naur linux-2.5.50-js/drivers/video/Makefile linux/drivers/video/Makefile
--- linux-2.5.50-js/drivers/video/Makefile 2002-12-04 15:15:25.000000000 +0000
+++ linux/drivers/video/Makefile 2002-12-04 15:14:40.000000000 +0000
@@ -6,7 +6,7 @@
# This list comes from 'grep -l EXPORT_SYMBOL *.[hc]'.

export-objs := fbmem.o fbcmap.o fbmon.o modedb.o softcursor.o cfbfillrect.o \
- cfbcopyarea.o cfbimgblt.o cyber2000fb.o
+ cfbcopyarea.o cfbimgblt.o cyber2000fb.o vgastate.o

# Each configuration option enables a list of files.

diff -Naur linux-2.5.50-js/drivers/video/vgastate.c linux/drivers/video/vgastate.c
--- linux-2.5.50-js/drivers/video/vgastate.c 1970-01-01 00:00:00.000000000 +0000
+++ linux/drivers/video/vgastate.c 2002-12-04 15:14:17.000000000 +0000
@@ -0,0 +1,438 @@
+/*
+ * linux/include/video/vgastate.c -- VGA state save/restore
+ *
+ * Copyright 2002 James Simmons
+ *
+ * Copyright history from vga16fb.c:
+ * Copyright 1999 Ben Pfaff and Petr Vandrovec
+ * Based on VGA info at http://www.goodnet.com/~tinara/FreeVGA/home.htm
+ * Based on VESA framebuffer (c) 1998 Gerd Knorr
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file COPYING in the main directory of this
+ * archive for more details.
+ *
+ */
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/fb.h>
+
+#include "vga.h"
+
+static inline unsigned char vga_rcrtcs(caddr_t regbase, unsigned short iobase,
+ unsigned char reg)
+{
+ vga_w(regbase, iobase + 0x4, reg);
+ return vga_r(regbase, iobase + 0x5);
+}
+
+static inline void vga_wcrtcs(caddr_t regbase, unsigned short iobase,
+ unsigned char reg, unsigned char val)
+{
+ vga_w(regbase, iobase + 0x4, reg);
+ vga_w(regbase, iobase + 0x5, val);
+}
+
+static void save_vga_text(struct fb_vgastate *state)
+{
+ int i;
+ u8 misc, attr10, gr4, gr5, gr6, seq1, seq2, seq4;
+
+ /* if in graphics mode, no need to save */
+ attr10 = vga_rattr(state->vgabase, 0x10);
+ if (attr10 & 1)
+ return;
+
+ /* save regs */
+ misc = vga_r(state->vgabase, VGA_MIS_R);
+ gr4 = vga_rgfx(state->vgabase, VGA_GFX_PLANE_READ);
+ gr5 = vga_rgfx(state->vgabase, VGA_GFX_MODE);
+ gr6 = vga_rgfx(state->vgabase, VGA_GFX_MISC);
+ seq2 = vga_rseq(state->vgabase, VGA_SEQ_PLANE_WRITE);
+ seq4 = vga_rseq(state->vgabase, VGA_SEQ_MEMORY_MODE);
+
+ /* force graphics mode */
+ vga_w(state->vgabase, VGA_MIS_W, misc | 1);
+
+ /* blank screen */
+ seq1 = vga_rseq(state->vgabase, VGA_SEQ_CLOCK_MODE);
+ vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
+ vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1 | 1 << 5);
+ vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x3);
+
+ /* save font 0 */
+ if (state->flags & VGA_SAVE_FONT0) {
+ vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x4);
+ vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+ vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x2);
+ vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+ vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+ for (i = 0; i < 8 * 8192; i++)
+ state->vga_font0[i] = vga_r(state->fbbase, i);
+ }
+ /* save font 1 */
+ if (state->flags & VGA_SAVE_FONT1) {
+ vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x8);
+ vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+ vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x3);
+ vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+ vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+ for (i = 0; i < 8 * 8192; i++)
+ state->vga_font1[i] = vga_r(state->fbbase, i);
+ }
+ /* save font 2 */
+ if (state->flags & VGA_SAVE_TEXT) {
+ vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x1);
+ vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+ vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x0);
+ vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+ vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+ for (i = 0; i < 2 * 8192; i++)
+ state->vga_text[i] = vga_r(state->fbbase, i);
+
+ vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x2);
+ vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+ vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x1);
+ vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+ vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+ for (i = 0; i < 2 * 8192; i++)
+ state->vga_text[i] = vga_r(state->fbbase +
+ 2 * 8192, i);
+ }
+
+ /* restore regs */
+ vga_wattr(state->vgabase, 0x10, attr10);
+
+ vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, seq2);
+ vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, seq4);
+
+ vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, gr4);
+ vga_wgfx(state->vgabase, VGA_GFX_MODE, gr5);
+ vga_wgfx(state->vgabase, VGA_GFX_MISC, gr6);
+ vga_w(state->vgabase, VGA_MIS_W, misc);
+
+ /* unblank screen */
+ vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
+ vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1 & ~(1 << 5));
+ vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x3);
+
+ vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1);
+}
+
+static void restore_vga_text(struct fb_vgastate *state)
+{
+ int i;
+ u8 misc, gr1, gr3, gr4, gr5, gr6, gr8;
+ u8 seq1, seq2, seq4;
+
+ /* save regs */
+ misc = vga_r(state->vgabase, VGA_MIS_R);
+ gr1 = vga_rgfx(state->vgabase, VGA_GFX_SR_ENABLE);
+ gr3 = vga_rgfx(state->vgabase, VGA_GFX_DATA_ROTATE);
+ gr4 = vga_rgfx(state->vgabase, VGA_GFX_PLANE_READ);
+ gr5 = vga_rgfx(state->vgabase, VGA_GFX_MODE);
+ gr6 = vga_rgfx(state->vgabase, VGA_GFX_MISC);
+ gr8 = vga_rgfx(state->vgabase, VGA_GFX_BIT_MASK);
+ seq2 = vga_rseq(state->vgabase, VGA_SEQ_PLANE_WRITE);
+ seq4 = vga_rseq(state->vgabase, VGA_SEQ_MEMORY_MODE);
+
+ /* force graphics mode */
+ vga_w(state->vgabase, VGA_MIS_W, misc | 1);
+
+ /* blank screen */
+ seq1 = vga_rseq(state->vgabase, VGA_SEQ_CLOCK_MODE);
+ vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
+ vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1 | 1 << 5);
+ vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x3);
+
+ if (state->depth == 4) {
+ vga_wgfx(state->vgabase, VGA_GFX_DATA_ROTATE, 0x0);
+ vga_wgfx(state->vgabase, VGA_GFX_BIT_MASK, 0xff);
+ vga_wgfx(state->vgabase, VGA_GFX_SR_ENABLE, 0x00);
+ }
+ /* restore font 0 */
+ if (state->flags & VGA_SAVE_FONT0) {
+ vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x4);
+ vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+ vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x2);
+ vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+ vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+ for (i = 0; i < 8 * 8192; i++)
+ vga_w(state->fbbase, i, state->vga_font0[i]);
+ }
+ /* restore font 1 */
+ if (state->flags & VGA_SAVE_FONT1) {
+ vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x8);
+ vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+ vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x3);
+ vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+ vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+ for (i = 0; i < 8 * 8192; i++)
+ vga_w(state->fbbase, i, state->vga_font1[i]);
+ }
+ /* restore font 2 */
+ if (state->flags & VGA_SAVE_TEXT) {
+ vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x1);
+ vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+ vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x0);
+ vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+ vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+ for (i = 0; i < 2 * 8192; i++)
+ vga_w(state->fbbase, i, state->vga_text[i]);
+
+ vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, 0x2);
+ vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, 0x6);
+ vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, 0x1);
+ vga_wgfx(state->vgabase, VGA_GFX_MODE, 0x0);
+ vga_wgfx(state->vgabase, VGA_GFX_MISC, 0x5);
+ for (i = 0; i < 2 * 8192; i++)
+ vga_w(state->fbbase + 2 * 8192, i,
+ state->vga_text[i]);
+ }
+ /* unblank screen */
+ vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
+ vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1 & ~(1 << 5));
+ vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x3);
+
+ /* restore regs */
+ vga_w(state->vgabase, VGA_MIS_W, misc);
+
+ vga_wgfx(state->vgabase, VGA_GFX_SR_ENABLE, gr1);
+ vga_wgfx(state->vgabase, VGA_GFX_DATA_ROTATE, gr3);
+ vga_wgfx(state->vgabase, VGA_GFX_PLANE_READ, gr4);
+ vga_wgfx(state->vgabase, VGA_GFX_MODE, gr5);
+ vga_wgfx(state->vgabase, VGA_GFX_MISC, gr6);
+ vga_wgfx(state->vgabase, VGA_GFX_BIT_MASK, gr8);
+
+ vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE, seq1);
+ vga_wseq(state->vgabase, VGA_SEQ_PLANE_WRITE, seq2);
+ vga_wseq(state->vgabase, VGA_SEQ_MEMORY_MODE, seq4);
+}
+
+static void save_vga_mode(struct fb_vgastate *state)
+{
+ unsigned short iobase;
+ int i;
+
+ state->misc = vga_r(state->vgabase, VGA_MIS_R);
+ if (state->misc & 1)
+ iobase = 0x3d0;
+ else
+ iobase = 0x3b0;
+
+ for (i = 0; i < state->num_crtc; i++)
+ state->crtc[i] = vga_rcrtcs(state->vgabase, iobase, i);
+
+ vga_r(state->vgabase, iobase + 0xa);
+ vga_w(state->vgabase, VGA_ATT_W, 0x00);
+ for (i = 0; i < state->num_attr; i++) {
+ vga_r(state->vgabase, iobase + 0xa);
+ state->attr[i] = vga_rattr(state->vgabase, i);
+ }
+ vga_r(state->vgabase, iobase + 0xa);
+ vga_w(state->vgabase, VGA_ATT_W, 0x20);
+
+ for (i = 0; i < state->num_gfx; i++)
+ state->gfx[i] = vga_rgfx(state->vgabase, i);
+
+ for (i = 0; i < state->num_seq; i++)
+ state->seq[i] = vga_rseq(state->vgabase, i);
+}
+
+static void restore_vga_mode(struct fb_vgastate *state)
+{
+ unsigned short iobase;
+ int i;
+
+ vga_w(state->vgabase, VGA_MIS_W, state->misc);
+
+ if (state->misc & 1)
+ iobase = 0x3d0;
+ else
+ iobase = 0x3b0;
+
+ vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x01);
+ vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE,
+ state->seq[VGA_SEQ_CLOCK_MODE] | 0x20);
+
+ for (i = 2; i < state->num_seq; i++)
+ vga_wseq(state->vgabase, i, state->seq[i]);
+
+ vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x03);
+
+ /* unprotect vga regs */
+ vga_wcrtcs(state->vgabase, iobase, 17, state->crtc[17] & ~0x80);
+ for (i = 0; i < state->num_crtc; i++)
+ vga_wcrtcs(state->vgabase, iobase, i, state->crtc[i]);
+
+ for (i = 0; i < state->num_gfx; i++)
+ vga_wgfx(state->vgabase, i, state->gfx[i]);
+
+ vga_r(state->vgabase, iobase + 0xa);
+ vga_w(state->vgabase, VGA_ATT_W, 0x00);
+ for (i = 0; i < state->num_attr; i++) {
+ vga_r(state->vgabase, iobase + 0xa);
+ vga_wattr(state->vgabase, i, state->attr[i]);
+ }
+
+ vga_wseq(state->vgabase, VGA_SEQ_CLOCK_MODE,
+ state->seq[VGA_SEQ_CLOCK_MODE]);
+
+ vga_r(state->vgabase, iobase + 0xa);
+ vga_w(state->vgabase, VGA_ATT_W, 0x20);
+}
+
+static void save_vga_cmap(struct fb_vgastate *state)
+{
+ int i;
+
+ vga_w(state->vgabase, VGA_PEL_MSK, 0xff);
+
+ /* assumes DAC is readable and writable */
+ vga_w(state->vgabase, VGA_PEL_IR, 0x00);
+ for (i = 0; i < 768; i++)
+ state->vga_cmap[i] = vga_r(state->vgabase, VGA_PEL_D);
+}
+
+static void restore_vga_cmap(struct fb_vgastate *state)
+{
+ int i;
+
+ vga_w(state->vgabase, VGA_PEL_MSK, 0xff);
+
+ vga_w(state->vgabase, VGA_PEL_IW, 0x00);
+ for (i = 0; i < 768; i++)
+ vga_w(state->vgabase, VGA_PEL_D, state->vga_cmap[i]);
+}
+
+static void vga_cleanup(struct fb_vgastate *state)
+{
+ if (state->vga_font0)
+ kfree(state->vga_font0);
+ if (state->vga_font1)
+ kfree(state->vga_font1);
+ if (state->vga_text)
+ kfree(state->vga_text);
+ if (state->fbbase)
+ iounmap(state->fbbase);
+ if (state->vga_cmap)
+ kfree(state->vga_cmap);
+ if (state->attr)
+ kfree(state->attr);
+ if (state->crtc)
+ kfree(state->crtc);
+ if (state->gfx)
+ kfree(state->gfx);
+ if (state->seq)
+ kfree(state->seq);
+}
+
+int fb_save_vga(struct fb_vgastate *state)
+{
+ state->vga_font0 = NULL;
+ state->vga_font1 = NULL;
+ state->vga_text = NULL;
+ state->vga_cmap = NULL;
+ state->attr = NULL;
+ state->crtc = NULL;
+ state->gfx = NULL;
+ state->seq = NULL;
+
+ if (state->flags & VGA_SAVE_CMAP) {
+ state->vga_cmap = kmalloc(768, GFP_KERNEL);
+ if (!state->vga_cmap) {
+ vga_cleanup(state);
+ return 1;
+ }
+ save_vga_cmap(state);
+ }
+
+ if (state->flags & VGA_SAVE_MODE) {
+ if (state->num_attr < 21)
+ state->num_attr = 21;
+ if (state->num_crtc < 25)
+ state->num_crtc = 25;
+ if (state->num_gfx < 9)
+ state->num_gfx = 9;
+ if (state->num_seq < 5)
+ state->num_seq = 5;
+ state->attr = kmalloc(state->num_attr, GFP_KERNEL);
+ state->crtc = kmalloc(state->num_crtc, GFP_KERNEL);
+ state->gfx = kmalloc(state->num_gfx, GFP_KERNEL);
+ state->seq = kmalloc(state->num_seq, GFP_KERNEL);
+ if (!state->attr || !state->crtc || !state->gfx ||
+ !state->seq) {
+ vga_cleanup(state);
+ return 1;
+ }
+ save_vga_mode(state);
+ }
+
+ if (state->flags & VGA_SAVE_FONT0) {
+ state->vga_font0 = kmalloc(8192 * 8, GFP_KERNEL);
+ if (!state->vga_font0) {
+ vga_cleanup(state);
+ return 1;
+ }
+ }
+ if (state->flags & VGA_SAVE_FONT1) {
+ state->vga_font1 = kmalloc(8192 * 8, GFP_KERNEL);
+ if (!state->vga_font1) {
+ vga_cleanup(state);
+ return 1;
+ }
+ }
+ if (state->flags & VGA_SAVE_TEXT) {
+ state->vga_text = kmalloc(8192 * 4, GFP_KERNEL);
+ if (!state->vga_text) {
+ vga_cleanup(state);
+ return 1;
+ }
+ }
+ if (state->flags & VGA_SAVE_FONTS) {
+ state->fbbase = ioremap(0xA0000, 8 * 8192);
+ if (!state->fbbase) {
+ vga_cleanup(state);
+ return 1;
+ }
+ save_vga_text(state);
+ iounmap(state->fbbase);
+ state->fbbase = NULL;
+ }
+ return 0;
+}
+
+int fb_restore_vga (struct fb_vgastate *state)
+{
+ if (state->flags & VGA_SAVE_MODE)
+ restore_vga_mode(state);
+
+ if (state->flags & VGA_SAVE_FONTS) {
+ state->fbbase = ioremap(0xA0000, 8 * 8192);
+ if (!state->fbbase) {
+ vga_cleanup(state);
+ return 1;
+ }
+ restore_vga_text(state);
+ }
+
+ if (state->flags & VGA_SAVE_CMAP)
+ restore_vga_cmap(state);
+
+ vga_cleanup(state);
+ return 0;
+}
+
+#ifdef MODULE
+int init_module(void) { return 0; };
+void cleanup_module(void) {};
+#endif
+
+EXPORT_SYMBOL(fb_save_vga);
+EXPORT_SYMBOL(fb_restore_vga);
+
+MODULE_AUTHOR("James Simmons <jsimmons@users.sf.net>");
+MODULE_DESCRIPTION("VGA State Save/Restore");
+MODULE_LICENSE("GPL");
+
diff -Naur linux-2.5.50-js/include/linux/fb.h linux/include/linux/fb.h
--- linux-2.5.50-js/include/linux/fb.h 2002-12-04 15:07:13.000000000 +0000
+++ linux/include/linux/fb.h 2002-12-04 15:20:00.000000000 +0000
@@ -321,6 +321,37 @@
struct fb_image image; /* Cursor image */
};

+/* VGA State Save and Restore */
+#define VGA_SAVE_FONT0 1 /* save/restore plane 2 fonts */
+#define VGA_SAVE_FONT1 2 /* save/restore plane 3 fonts */
+#define VGA_SAVE_TEXT 4 /* save/restore plane 0/1 fonts */
+#define VGA_SAVE_FONTS 7 /* save/restore all fonts */
+#define VGA_SAVE_MODE 8 /* save/restore video mode */
+#define VGA_SAVE_CMAP 16 /* save/restore color map/DAC */
+
+struct fb_vgastate {
+ caddr_t vgabase; /* mmio base, if supported */
+ __u32 flags; /* what state/s to save (see VGA_SAVE_*) */
+ __u32 depth; /* current fb depth, not important */
+ __u32 num_attr; /* number of att registers, 0 for default */
+ __u32 num_crtc; /* number of crt registers, 0 for default */
+ __u32 num_gfx; /* number of gfx registers, 0 for default */
+ __u32 num_seq; /* number of seq registers, 0 for default */
+ caddr_t fbbase; /* -- DO NOT ALTER STARTING HERE -- */
+ __u8 *vga_font0;
+ __u8 *vga_font1;
+ __u8 *vga_text;
+ __u8 *vga_cmap;
+ __u8 *attr;
+ __u8 *crtc;
+ __u8 *gfx;
+ __u8 *seq;
+ __u8 misc;
+};
+
+extern int fb_save_vga(struct fb_vgastate *state);
+extern int fb_restore_vga(struct fb_vgastate *state);
+
#ifdef __KERNEL__

#include <linux/fs.h>
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