Re: [PATCH 5/5]: fbcon module unloading

[Antonino Daplas <adaplas@subdimension.com>]

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On Sun, 2003-02-16 at 14:09, Antonino Daplas wrote:
> Attached is a rediff (linux-2.5.61 + James' fbdev.diff) to enable fbcon module unloading.
> 

Oops.  Please disregard the previous patch.  Attached is an updated
diff.

Tony

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diff -Naur linux-2.5.61-fbdev/drivers/char/vt.c linux-2.5.61-ad/drivers/char/vt.c
--- linux-2.5.61-fbdev/drivers/char/vt.c	2003-02-16 00:55:52.000000000 +0000
+++ linux-2.5.61-ad/drivers/char/vt.c	2003-02-16 06:17:36.000000000 +0000
@@ -109,6 +109,7 @@
 
 
 const struct consw *conswitchp;
+const struct consw *defcsw = NULL; /* for recovery of default console */
 
 /* A bitmap for codes <32. A bit of 1 indicates that the code
  * corresponding to that bit number invokes some special action
@@ -2571,10 +2572,14 @@
 	int i, j = -1;
 	const char *desc;
 
+	if (deflt && defcsw != NULL)
+		return;
 	desc = csw->con_startup();
 	if (!desc) return;
-	if (deflt)
+	if (deflt) {
+		defcsw = conswitchp;
 		conswitchp = csw;
+	}
 
 	for (i = first; i <= last; i++) {
 		int old_was_color;
@@ -2616,11 +2621,78 @@
 
 void give_up_console(const struct consw *csw)
 {
-	int i;
+	const char *desc;
+	int i, j = -1, first = -1, last = -1;
 
-	for(i = 0; i < MAX_NR_CONSOLES; i++)
-		if (con_driver_map[i] == csw)
+	for(i = 0; i < MAX_NR_CONSOLES; i++) {
+		if (con_driver_map[i] == csw) {
+			if (first == -1)
+				first = i;
+			last = i;
 			con_driver_map[i] = NULL;
+		}
+	}
+
+	if (defcsw == NULL)
+		return;
+	conswitchp = defcsw;
+	defcsw = NULL;
+
+	desc = conswitchp->con_startup();
+	if (!desc) return;
+
+	for (i = first; i <= last; i++) {
+		int old_was_color;
+		int currcons = i;
+
+		con_driver_map[i] = conswitchp;
+
+		if (!vc_cons[i].d || !vc_cons[i].d->vc_sw)
+			continue;
+		j = i;
+		if (IS_VISIBLE)
+			save_screen(i);
+		old_was_color = vc_cons[i].d->vc_can_do_color;
+		vc_cons[i].d->vc_sw->con_deinit(vc_cons[i].d);
+		visual_init(i, 0);
+		set_origin(i);
+
+		/*
+		 * partial reset_terminal()
+		 */
+		top = 0;
+		bottom = video_num_lines;
+		gotoxy(i, x, y);
+		save_cur(i);
+		update_attr(i);
+
+
+		/* If the console changed between mono <-> color, then
+		 * the attributes in the screenbuf will be wrong.  The
+		 * following resets all attributes to something sane.
+		 */
+		if (old_was_color != vc_cons[i].d->vc_can_do_color ||
+		    IS_VISIBLE)
+			clear_buffer_attributes(i);
+
+		if (IS_VISIBLE)
+			update_screen(i);
+		if (vc_cons[i].d->vc_tty) {
+			kill_pg(vc_cons[i].d->vc_tty->pgrp, SIGWINCH, 1);
+			vc_cons[i].d->vc_tty->winsize.ws_col = 
+				video_num_columns;
+			vc_cons[i].d->vc_tty->winsize.ws_row = 
+				video_num_lines;
+		}
+	}
+	printk("Console: switching ");
+	if (j >= 0)
+		printk("to %s %s %dx%d\n",
+		       vc_cons[j].d->vc_can_do_color ? "colour" : "mono",
+		       desc, vc_cons[j].d->vc_cols, vc_cons[j].d->vc_rows);
+	else
+		printk("to %s\n", desc);
+
 }
 
 #endif
diff -Naur linux-2.5.61-fbdev/drivers/video/console/Kconfig linux-2.5.61-ad/drivers/video/console/Kconfig
--- linux-2.5.61-fbdev/drivers/video/console/Kconfig	2003-02-16 00:49:23.000000000 +0000
+++ linux-2.5.61-ad/drivers/video/console/Kconfig	2003-02-16 06:17:36.000000000 +0000
@@ -106,6 +106,19 @@
 	tristate "Framebuffer Console support"
 	depends on FB
 
+config FRAMEBUFFER_CONSOLE_UNLOAD
+	bool "Allow Framebuffer Console Module Unloading (DANGEROUS)"
+	depends on FRAMEBUFFER_CONSOLE=m
+	default n
+	---help---
+          If you say Y, the framebuffer console module can be unloaded 
+          and the console reverted to the default console driver that was
+          loaded at boot time.  Not all drivers support unloading, and even
+          if it does, it might leave you with a corrupted display.
+
+          Unless you are a framebuffer driver developer, or you really know
+          what you're doing, say N here.
+
 config PCI_CONSOLE
 	bool
 	depends on FRAMEBUFFER_CONSOLE
diff -Naur linux-2.5.61-fbdev/drivers/video/console/fbcon.c linux-2.5.61-ad/drivers/video/console/fbcon.c
--- linux-2.5.61-fbdev/drivers/video/console/fbcon.c	2003-02-16 00:55:52.000000000 +0000
+++ linux-2.5.61-ad/drivers/video/console/fbcon.c	2003-02-16 06:18:29.000000000 +0000
@@ -146,6 +146,7 @@
 static int vbl_cursor_cnt;
 static int cursor_on;
 static int cursor_blink_rate;
+static int irqres = 1;
 
 static inline void cursor_undrawn(void)
 {
@@ -199,6 +200,23 @@
 static void fbcon_bmove_rec(struct display *p, int sy, int sx, int dy,
 			    int dx, int height, int width, u_int y_break);
 
+/*
+ * fbcon module unloading 
+ */
+
+#ifdef CONFIG_FRAMEBUFFER_CONSOLE_UNLOAD
+static void __init fbcon_mod_unload(struct fb_info *info)
+{
+	if (!info->fbops->fb_release)
+		__unsafe(THIS_MODULE);
+}
+#else
+static void __init fbcon_mod_unload(struct fb_info *info)
+{
+	__unsafe(THIS_MODULE);
+}
+#endif /* CONFIG_FRAMEBUFFER_CONSOLE_UNLOAD */
+
 #ifdef CONFIG_MAC
 /*
  * On the Macintoy, there may or may not be a working VBL int. We need to probe
@@ -580,7 +598,7 @@
 	struct fb_info *info;
 	struct vc_data *vc;
 	static int done = 0;
-	int irqres = 1;
+	int i;
 
 	/*
 	 *  If num_registered_fb is zero, this is a call for the dummy part.
@@ -590,8 +608,11 @@
 		return display_desc;
 	done = 1;
 
-	info = registered_fb[num_registered_fb-1];	
-	if (!info)	return NULL;
+	for (i = 0; i < FB_MAX; i++) {
+		info = registered_fb[i];	
+		if (info != NULL)
+			break;
+	}
 	info->currcon = -1;
 	
 	owner = info->fbops->owner;
@@ -2558,19 +2579,89 @@
 
 int __init fb_console_init(void)
 {
+	struct fb_info *info = NULL;
+	int i, unit = 0;
+
 	if (!num_registered_fb)
 		return -ENODEV;
+	for (i = 0; i < FB_MAX; i++) {
+		info = registered_fb[i];
+		if (info != NULL) {
+			unit = i;
+			break;
+		}
+	}
+	for (i = 0; i < MAX_NR_CONSOLES; i++)
+		con2fb_map[i] = unit;
 	take_over_console(&fb_con, first_fb_vc, last_fb_vc, fbcon_is_default);
+	fbcon_mod_unload(info);
+	return 0;
+}
+
+#ifdef CONFIG_FRAMEBUFFER_CONSOLE_UNLOAD
+static int __exit fbcon_exit(void) 
+{
+	struct fb_info *info;
+	int i, j, mapped;
+
+	for (i = 0; i < FB_MAX; i++) {
+		info = registered_fb[i];
+		if (info != NULL && !info->fbops->fb_release)
+			return -EINVAL;
+	}
+
+	if (irqres) {
+		del_timer_sync(&cursor_timer);
+	} else {
+#ifdef CONFIG_AMIGA
+		if (MACH_IS_AMIGA) 
+			free_irq(IRQ_AMIGA_VERTB, fbcon_vbl_handler);
+#endif				/* CONFIG_AMIGA */
+#ifdef CONFIG_ATARI
+		if (MACH_IS_ATARI) 
+			free_irq(IRQ_AUTO_4, fbcon_vbl_handler);
+#endif				/* CONFIG_ATARI */
+#ifdef CONFIG_MAC
+		if (MACH_IS_MAC && vbl_detected) 
+			free_irq(IRQ_MAC_VBL, fbcon_vbl_handler);
+#endif				/* CONFIG_MAC */
+#if defined(__arm__) && defined(IRQ_VSYNCPULSE)
+		free_irq(IRQ_VSYNCPULSE, fbcon_vbl_handler);
+#endif
+	}
+	if (softback_buf) 
+		kfree((void *) softback_buf);
+
+	for (i = 0; i < FB_MAX; i++) {
+		mapped = 0;
+		info = registered_fb[i];
+		if (info == NULL)
+			continue;
+		for (j = 0; j < MAX_NR_CONSOLES; j++) {
+			if (con2fb_map[j] == i) {
+				con2fb_map[j] = -1;
+				mapped = 1;
+			}
+		}
+		if (mapped) {
+			info->fbops->fb_release(info, 0); 
+			module_put(info->fbops->owner);
+			kfree(info->display_fg);
+		}
+	}
 	return 0;
 }
 
 void __exit fb_console_exit(void)
 {
+	if (fbcon_exit())
+		return;
 	give_up_console(&fb_con);
 }	
+module_exit(fb_console_exit);
+#endif /* CONFIG_FRAMEBUFFER_CONSOLE_UNLOAD */
 
 module_init(fb_console_init);
-module_exit(fb_console_exit);
 
 /*
  *  Visible symbols for modules