tty: vt, cleanup and document con_scroll

Scrolling helpers scrup and scrdown both accept 'top' and 'bottom' as
unsigned int. Number of lines 'nr' is accepted as int, but all callers
pass down unsigned too. So change the type of 'nr' to unsigned too.
Now, promote unsigned int from the helpers up to the con_scroll
hook which actually accepted all those as signed int.

Next, the 'dir' parameter can have only two values and we define
constants for that: SM_UP and SM_DOWN. Switch them to enum and do
proper type checking on 'dir' too.

Finally, document the behaviour of the hook.

Signed-off-by: Jiri Slaby <[e-mail]>
Cc: Thomas Winischhofer <[e-mail]>
Cc: Tomi Valkeinen <[e-mail]>
Cc: "James E.J. Bottomley" <[e-mail]>
Cc: Helge Deller <[e-mail]>
Cc: <[e-mail]>
Cc: <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/vt/vt.c

···
 	schedule_work(&console_work);
 }
 
-static void scrup(struct vc_data *vc, unsigned int t, unsigned int b, int nr)
+static void scrup(struct vc_data *vc, unsigned int t, unsigned int b,
+		unsigned int nr)
 {
 	unsigned short *d, *s;
 
···
 		    vc->vc_size_row * nr);
 }
 
-static void scrdown(struct vc_data *vc, unsigned int t, unsigned int b, int nr)
+static void scrdown(struct vc_data *vc, unsigned int t, unsigned int b,
+		unsigned int nr)
 {
 	unsigned short *s;
 	unsigned int step;

drivers/usb/misc/sisusbvga/sisusb_con.c

···
 	mutex_unlock(&sisusb->lock);
 }
 
-static int
+static bool
 sisusbcon_scroll_area(struct vc_data *c, struct sisusb_usb_data *sisusb,
-					int t, int b, int dir, int lines)
+		unsigned int t, unsigned int b, enum con_scroll dir,
+		unsigned int lines)
 {
 	int cols = sisusb->sisusb_num_columns;
 	int length = ((b - t) * cols) * 2;
···
 }
 
 /* Interface routine */
-static int
-sisusbcon_scroll(struct vc_data *c, int t, int b, int dir, int lines)
+static bool
+sisusbcon_scroll(struct vc_data *c, unsigned int t, unsigned int b,
+		enum con_scroll dir, unsigned int lines)
 {
 	struct sisusb_usb_data *sisusb;
 	u16 eattr = c->vc_video_erase_char;
···
 	 */
 
 	if (!lines)
-		return 1;
+		return true;
 
 	sisusb = sisusb_get_sisusb_lock_and_check(c->vc_num);
 	if (!sisusb)
-		return 0;
+		return false;
 
 	/* sisusb->lock is down */
 
 	if (sisusb_is_inactive(c, sisusb)) {
 		mutex_unlock(&sisusb->lock);
-		return 0;
+		return false;
 	}
 
 	/* Special case */
···
 
 	mutex_unlock(&sisusb->lock);
 
-	return 1;
+	return true;
 }
 
 /* Interface routine */

drivers/video/console/fbcon.c

···
 			int count, int ypos, int xpos);
 static void fbcon_clear_margins(struct vc_data *vc, int bottom_only);
 static void fbcon_cursor(struct vc_data *vc, int mode);
-static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
-			int count);
 static void fbcon_bmove(struct vc_data *vc, int sy, int sx, int dy, int dx,
 			int height, int width);
 static int fbcon_switch(struct vc_data *vc);
···
 	softback_curr = softback_in;
 }
 
-static int fbcon_scroll(struct vc_data *vc, int t, int b, int dir,
-			int count)
+static bool fbcon_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
+		enum con_scroll dir, unsigned int count)
 {
 	struct fb_info *info = registered_fb[con2fb_map[vc->vc_num]];
 	struct display *p = &fb_display[vc->vc_num];
 	int scroll_partial = info->flags & FBINFO_PARTIAL_PAN_OK;
 
 	if (fbcon_is_inactive(vc, info))
-		return -EINVAL;
+		return true;
 
 	fbcon_cursor(vc, CM_ERASE);
 
···
 							(b - count)),
 				    vc->vc_video_erase_char,
 				    vc->vc_size_row * count);
-			return 1;
+			return true;
 			break;
 
 		case SCROLL_WRAP_MOVE:
···
 							(b - count)),
 				    vc->vc_video_erase_char,
 				    vc->vc_size_row * count);
-			return 1;
+			return true;
 		}
 		break;
 
···
 							t),
 				    vc->vc_video_erase_char,
 				    vc->vc_size_row * count);
-			return 1;
+			return true;
 			break;
 
 		case SCROLL_WRAP_MOVE:
···
 							t),
 				    vc->vc_video_erase_char,
 				    vc->vc_size_row * count);
-			return 1;
+			return true;
 		}
 	}
-	return 0;
+	return false;
 }
 
 

drivers/video/console/mdacon.c

···
 	}
 }
 
-static int mdacon_scroll(struct vc_data *c, int t, int b, int dir, int lines)
+static bool mdacon_scroll(struct vc_data *c, unsigned int t, unsigned int b,
+		enum con_scroll dir, unsigned int lines)
 {
 	u16 eattr = mda_convert_attr(c->vc_video_erase_char);
 
 	if (!lines)
-		return 0;
+		return false;
 
 	if (lines > c->vc_rows)   /* maximum realistic size */
 		lines = c->vc_rows;
···
 		break;
 	}
 
-	return 0;
+	return false;
 }
 
 

drivers/video/console/newport_con.c

···
 	return newport_set_font(vc->vc_num, font);
 }
 
-static int newport_scroll(struct vc_data *vc, int t, int b, int dir,
-			  int lines)
+static bool newport_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
+		enum con_scroll dir, unsigned int lines)
 {
 	int count, x, y;
 	unsigned short *s, *d;
···
 					    (vc->vc_color & 0xf0) >> 4);
 		}
 		npregs->cset.topscan = (topscan - 1) & 0x3ff;
-		return 0;
+		return false;
 	}
 
 	count = (b - t - lines) * vc->vc_cols;
···
 			}
 		}
 	}
-	return 1;
+	return true;
 }
 
 static int newport_dummy(struct vc_data *c)

drivers/video/console/sticon.c

···
     }
 }
 
-static int sticon_scroll(struct vc_data *conp, int t, int b, int dir, int count)
+static bool sticon_scroll(struct vc_data *conp, unsigned int t,
+		unsigned int b, enum con_scroll dir, unsigned int count)
 {
     struct sti_struct *sti = sticon_sti;
 
     if (vga_is_gfx)
-        return 0;
+        return false;
 
     sticon_cursor(conp, CM_ERASE);
 
···
 	break;
     }
 
-    return 0;
+    return false;
 }
 
 static void sticon_init(struct vc_data *c, int init)

drivers/video/console/vgacon.c

···
 static void vgacon_scrolldelta(struct vc_data *c, int lines);
 static int vgacon_set_origin(struct vc_data *c);
 static void vgacon_save_screen(struct vc_data *c);
-static int vgacon_scroll(struct vc_data *c, int t, int b, int dir,
-			 int lines);
 static void vgacon_invert_region(struct vc_data *c, u16 * p, int count);
 static struct uni_pagedir *vgacon_uni_pagedir;
 static int vgacon_refcount;
···
 			    c->vc_screenbuf_size > vga_vram_size ? vga_vram_size : c->vc_screenbuf_size);
 }
 
-static int vgacon_scroll(struct vc_data *c, int t, int b, int dir,
-			 int lines)
+static bool vgacon_scroll(struct vc_data *c, unsigned int t, unsigned int b,
+		enum con_scroll dir, unsigned int lines)
 {
 	unsigned long oldo;
 	unsigned int delta;
 
 	if (t || b != c->vc_rows || vga_is_gfx || c->vc_mode != KD_TEXT)
-		return 0;
+		return false;
 
 	if (!vga_hardscroll_enabled || lines >= c->vc_rows / 2)
-		return 0;
+		return false;
 
 	vgacon_restore_screen(c);
 	oldo = c->vc_origin;
···
 	c->vc_visible_origin = c->vc_origin;
 	vga_set_mem_top(c);
 	c->vc_pos = (c->vc_pos - oldo) + c->vc_origin;
-	return 1;
+	return true;
 }
 
 

include/linux/console.h

···
 #define VT100ID "\033[?1;2c"
 #define VT102ID "\033[?6c"
 
+enum con_scroll {
+	SM_UP,
+	SM_DOWN,
+};
+
 /**
  * struct consw - callbacks for consoles
  *
+ * @con_scroll: move lines from @top to @bottom in direction @dir by @lines.
+ *		Return true if no generic handling should be done.
+ *		Invoked by csi_M and printing to the console.
  * @con_set_palette: sets the palette of the console to @table (optional)
  * @con_scrolldelta: the contents of the console should be scrolled by @lines.
  *		     Invoked by user. (optional)
···
 	void	(*con_putc)(struct vc_data *, int, int, int);
 	void	(*con_putcs)(struct vc_data *, const unsigned short *, int, int, int);
 	void	(*con_cursor)(struct vc_data *, int);
-	int	(*con_scroll)(struct vc_data *, int, int, int, int);
+	bool	(*con_scroll)(struct vc_data *, unsigned int top,
+			unsigned int bottom, enum con_scroll dir,
+			unsigned int lines);
 	int	(*con_switch)(struct vc_data *);
 	int	(*con_blank)(struct vc_data *, int, int);
 	int	(*con_font_set)(struct vc_data *, struct console_font *, unsigned);
···
 	return 0;
 }
 #endif
-
-/* scroll */
-#define SM_UP       (1)
-#define SM_DOWN     (2)
 
 /* cursor */
 #define CM_DRAW     (1)