[PATCH] fbdev: Add mode changing via sysfs

This is a first pass at adding two new sysfs attributes to
/sys/class/graphics/fb0 for setting modes.  There are two attributes: modes
which contains a list of valid modes, and mode which is the current mode.  To
switch modes echo one of the entries from the modes list to the mode
attribute.

The D,V,S on the modes represents Detailed, Vesa, Standard from the DDC info.

modes is root writable.  It can also be used to set the list of modes.  For
example a /etc file could add modes that are not in the monitor's DDC.

mode is user writable.  PAM would set ownership of mode at user login time.
This provides a safe way for a user to set the mode without being root.  You
can only set the mode to one of the modes on the list.
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/video/fbmem.c

@@ -1059,7 +1059,6 @@ int
 register_framebuffer(struct fb_info *fb_info)
 {
 	int i;
-	struct class_device *c;
 	struct fb_event event;
 
 	if (num_registered_fb == FB_MAX)
@@ -1070,13 +1069,15 @@ register_framebuffer(struct fb_info *fb_info)
 			break;
 	fb_info->node = i;
 
-	c = class_simple_device_add(fb_class, MKDEV(FB_MAJOR, i),
+	fb_info->class_device = class_simple_device_add(fb_class, MKDEV(FB_MAJOR, i),
 				    fb_info->device, "fb%d", i);
-	if (IS_ERR(c)) {
+	if (IS_ERR(fb_info->class_device)) {
 		/* Not fatal */
-		printk(KERN_WARNING "Unable to create class_device for framebuffer %d; errno = %ld\n", i, PTR_ERR(c));
-	}
-	
+		printk(KERN_WARNING "Unable to create class_device for framebuffer %d; errno = %ld\n", i, PTR_ERR(fb_info->class_device));
+		fb_info->class_device = NULL;
+	} else
+		fb_init_class_device(fb_info);
+
 	if (fb_info->pixmap.addr == NULL) {
 		fb_info->pixmap.addr = kmalloc(FBPIXMAPSIZE, GFP_KERNEL);
 		if (fb_info->pixmap.addr) {
@@ -1135,6 +1136,7 @@ unregister_framebuffer(struct fb_info *fb_info)
 	fb_destroy_modelist(&fb_info->modelist);
 	registered_fb[i]=NULL;
 	num_registered_fb--;
+	fb_cleanup_class_device(fb_info);
 	class_simple_device_remove(MKDEV(FB_MAJOR, i));
 	return 0;
 }

drivers/video/fbsysfs.c

@@ -17,6 +17,7 @@
 
 #include <linux/kernel.h>
 #include <linux/fb.h>
+#include <linux/console.h>
 
 /**
  * framebuffer_alloc - creates a new frame buffer info structure
@@ -57,6 +58,7 @@ struct fb_info *framebuffer_alloc(size_t size, struct device *dev)
 #undef PADDING
 #undef BYTES_PER_LONG
 }
+EXPORT_SYMBOL(framebuffer_alloc);
 
 /**
  * framebuffer_release - marks the structure available for freeing
@@ -71,6 +73,307 @@ void framebuffer_release(struct fb_info *info)
 {
 	kfree(info);
 }
-
 EXPORT_SYMBOL(framebuffer_release);
-EXPORT_SYMBOL(framebuffer_alloc);
+
+static int activate(struct fb_info *fb_info, struct fb_var_screeninfo *var)
+{
+	int err;
+
+	var->activate |= FB_ACTIVATE_FORCE;
+	acquire_console_sem();
+	fb_info->flags |= FBINFO_MISC_USEREVENT;
+	err = fb_set_var(fb_info, var);
+	fb_info->flags &= ~FBINFO_MISC_USEREVENT;
+	release_console_sem();
+	if (err)
+		return err;
+	return 0;
+}
+
+static int mode_string(char *buf, unsigned int offset,
+		       const struct fb_videomode *mode)
+{
+	char m = 'U';
+	if (mode->flag & FB_MODE_IS_DETAILED)
+		m = 'D';
+	if (mode->flag & FB_MODE_IS_VESA)
+		m = 'V';
+	if (mode->flag & FB_MODE_IS_STANDARD)
+		m = 'S';
+	return snprintf(&buf[offset], PAGE_SIZE - offset, "%c:%dx%d-%d\n", m, mode->xres, mode->yres, mode->refresh);
+}
+
+static ssize_t store_mode(struct class_device *class_device, const char * buf,
+			  size_t count)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+	char mstr[100];
+	struct fb_var_screeninfo var;
+	struct fb_modelist *modelist;
+	struct fb_videomode *mode;
+	struct list_head *pos;
+	size_t i;
+	int err;
+
+	memset(&var, 0, sizeof(var));
+
+	list_for_each(pos, &fb_info->modelist) {
+		modelist = list_entry(pos, struct fb_modelist, list);
+		mode = &modelist->mode;
+		i = mode_string(mstr, 0, mode);
+		if (strncmp(mstr, buf, max(count, i)) == 0) {
+
+			var = fb_info->var;
+			fb_videomode_to_var(&var, mode);
+			if ((err = activate(fb_info, &var)))
+				return err;
+			fb_info->mode = mode;
+			return count;
+		}
+	}
+	return -EINVAL;
+}
+
+static ssize_t show_mode(struct class_device *class_device, char *buf)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+
+	if (!fb_info->mode)
+		return 0;
+
+	return mode_string(buf, 0, fb_info->mode);
+}
+
+static ssize_t store_modes(struct class_device *class_device, const char * buf,
+			   size_t count)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+	int i = count / sizeof(struct fb_videomode);
+	if (i * sizeof(struct fb_videomode) != count)
+		return -EINVAL;
+
+	fb_destroy_modelist(&fb_info->modelist);
+	fb_videomode_to_modelist((struct fb_videomode *)buf, i,
+				 &fb_info->modelist);
+
+	return 0;
+}
+
+static ssize_t show_modes(struct class_device *class_device, char *buf)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+	unsigned int i;
+	struct list_head *pos;
+	struct fb_modelist *modelist;
+	const struct fb_videomode *mode;
+
+	i = 0;
+	list_for_each(pos, &fb_info->modelist) {
+		modelist = list_entry(pos, struct fb_modelist, list);
+		mode = &modelist->mode;
+		i += mode_string(buf, i, mode);
+	}
+	return i;
+}
+
+static ssize_t store_bpp(struct class_device *class_device, const char * buf,
+			 size_t count)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+	struct fb_var_screeninfo var;
+	char ** last = NULL;
+	int err;
+
+	var = fb_info->var;
+	var.bits_per_pixel = simple_strtoul(buf, last, 0);
+	if ((err = activate(fb_info, &var)))
+		return err;
+	return count;
+}
+
+static ssize_t show_bpp(struct class_device *class_device, char *buf)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+	return snprintf(buf, PAGE_SIZE, "%d\n", fb_info->var.bits_per_pixel);
+}
+
+static ssize_t store_virtual(struct class_device *class_device,
+			     const char * buf, size_t count)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+	struct fb_var_screeninfo var;
+	char *last = NULL;
+	int err;
+
+	var = fb_info->var;
+	var.xres_virtual = simple_strtoul(buf, &last, 0);
+	last++;
+	if (last - buf >= count)
+		return -EINVAL;
+	var.yres_virtual = simple_strtoul(last, &last, 0);
+	printk(KERN_ERR "fb: xres %d yres %d\n", var.xres_virtual,
+	       var.yres_virtual);
+
+	if ((err = activate(fb_info, &var)))
+		return err;
+	return count;
+}
+
+static ssize_t show_virtual(struct class_device *class_device, char *buf)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+	return snprintf(buf, PAGE_SIZE, "%d,%d\n", fb_info->var.xres_virtual,
+			fb_info->var.xres_virtual);
+}
+
+static ssize_t store_cmap(struct class_device *class_device, const char * buf,
+			  size_t count)
+{
+//	struct fb_info *fb_info = (struct fb_info *)class_get_devdata(class_device);
+	return 0;
+}
+
+static ssize_t show_cmap(struct class_device *class_device, char *buf)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+	unsigned int offset = 0, i;
+
+	if (!fb_info->cmap.red || !fb_info->cmap.blue ||
+	    fb_info->cmap.green || fb_info->cmap.transp)
+		return -EINVAL;
+
+	for (i = 0; i < fb_info->cmap.len; i++) {
+		offset += snprintf(buf, PAGE_SIZE - offset,
+				   "%d,%d,%d,%d,%d\n", i + fb_info->cmap.start,
+				   fb_info->cmap.red[i], fb_info->cmap.blue[i],
+				   fb_info->cmap.green[i],
+				   fb_info->cmap.transp[i]);
+	}
+	return offset;
+}
+
+static ssize_t store_blank(struct class_device *class_device, const char * buf,
+			   size_t count)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+	char *last = NULL;
+	int err;
+
+	acquire_console_sem();
+	fb_info->flags |= FBINFO_MISC_USEREVENT;
+	err = fb_blank(fb_info, simple_strtoul(buf, &last, 0));
+	fb_info->flags &= ~FBINFO_MISC_USEREVENT;
+	release_console_sem();
+	if (err < 0)
+		return err;
+	return count;
+}
+
+static ssize_t show_blank(struct class_device *class_device, char *buf)
+{
+//	struct fb_info *fb_info = (struct fb_info *)class_get_devdata(class_device);
+	return 0;
+}
+
+static ssize_t store_console(struct class_device *class_device,
+			     const char * buf, size_t count)
+{
+//	struct fb_info *fb_info = (struct fb_info *)class_get_devdata(class_device);
+	return 0;
+}
+
+static ssize_t show_console(struct class_device *class_device, char *buf)
+{
+//	struct fb_info *fb_info = (struct fb_info *)class_get_devdata(class_device);
+	return 0;
+}
+
+static ssize_t store_cursor(struct class_device *class_device,
+			    const char * buf, size_t count)
+{
+//	struct fb_info *fb_info = (struct fb_info *)class_get_devdata(class_device);
+	return 0;
+}
+
+static ssize_t show_cursor(struct class_device *class_device, char *buf)
+{
+//	struct fb_info *fb_info = (struct fb_info *)class_get_devdata(class_device);
+	return 0;
+}
+
+static ssize_t store_pan(struct class_device *class_device, const char * buf,
+			 size_t count)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+	struct fb_var_screeninfo var;
+	char *last = NULL;
+	int err;
+
+	var = fb_info->var;
+	var.xoffset = simple_strtoul(buf, &last, 0);
+	last++;
+	if (last - buf >= count)
+		return -EINVAL;
+	var.yoffset = simple_strtoul(last, &last, 0);
+
+	acquire_console_sem();
+	err = fb_pan_display(fb_info, &var);
+	release_console_sem();
+
+	if (err < 0)
+		return err;
+	return count;
+}
+
+static ssize_t show_pan(struct class_device *class_device, char *buf)
+{
+	struct fb_info *fb_info =
+		(struct fb_info *)class_get_devdata(class_device);
+	return snprintf(buf, PAGE_SIZE, "%d,%d\n", fb_info->var.xoffset,
+			fb_info->var.xoffset);
+}
+
+struct class_device_attribute class_device_attrs[] = {
+	__ATTR(bits_per_pixel, S_IRUGO|S_IWUSR, show_bpp, store_bpp),
+	__ATTR(blank, S_IRUGO|S_IWUSR, show_blank, store_blank),
+	__ATTR(color_map, S_IRUGO|S_IWUSR, show_cmap, store_cmap),
+	__ATTR(console, S_IRUGO|S_IWUSR, show_console, store_console),
+	__ATTR(cursor, S_IRUGO|S_IWUSR, show_cursor, store_cursor),
+	__ATTR(mode, S_IRUGO|S_IWUSR, show_mode, store_mode),
+	__ATTR(modes, S_IRUGO|S_IWUSR, show_modes, store_modes),
+	__ATTR(pan, S_IRUGO|S_IWUSR, show_pan, store_pan),
+	__ATTR(virtual_size, S_IRUGO|S_IWUSR, show_virtual, store_virtual),
+};
+
+int fb_init_class_device(struct fb_info *fb_info)
+{
+	unsigned int i;
+	class_set_devdata(fb_info->class_device, fb_info);
+
+	for (i = 0; i < ARRAY_SIZE(class_device_attrs); i++)
+		class_device_create_file(fb_info->class_device,
+					 &class_device_attrs[i]);
+	return 0;
+}
+
+void fb_cleanup_class_device(struct fb_info *fb_info)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(class_device_attrs); i++)
+		class_device_remove_file(fb_info->class_device,
+					 &class_device_attrs[i]);
+}
+
+

include/linux/fb.h

@@ -715,8 +715,10 @@ struct fb_info {
 	struct fb_pixmap sprite;	/* Cursor hardware mapper */
 	struct fb_cmap cmap;		/* Current cmap */
 	struct list_head modelist;      /* mode list */
+	struct fb_videomode *mode;	/* current mode */
 	struct fb_ops *fbops;
 	struct device *device;
+	struct class_device *class_device; /* sysfs per device attrs */
 #ifdef CONFIG_FB_TILEBLITTING
 	struct fb_tile_ops *tileops;    /* Tile Blitting */
 #endif
@@ -833,6 +835,8 @@ extern int num_registered_fb;
 /* drivers/video/fbsysfs.c */
 extern struct fb_info *framebuffer_alloc(size_t size, struct device *dev);
 extern void framebuffer_release(struct fb_info *info);
+extern int fb_init_class_device(struct fb_info *fb_info);
+extern void fb_cleanup_class_device(struct fb_info *head);
 
 /* drivers/video/fbmon.c */
 #define FB_MAXTIMINGS		0