xref: /linux/drivers/video/fbdev/vfb.c (revision 6f52b16c5b29b89d92c0e7236f4655dc8491ad70) 
1 /*
2  *  linux/drivers/video/vfb.c -- Virtual frame buffer device
3  *
4  *      Copyright (C) 2002 James Simmons
5  *
6  *	Copyright (C) 1997 Geert Uytterhoeven
7  *
8  *  This file is subject to the terms and conditions of the GNU General Public
9  *  License. See the file COPYING in the main directory of this archive for
10  *  more details.
11  */
12 
13 #include <linux/module.h>
14 #include <linux/kernel.h>
15 #include <linux/errno.h>
16 #include <linux/string.h>
17 #include <linux/mm.h>
18 #include <linux/vmalloc.h>
19 #include <linux/delay.h>
20 #include <linux/interrupt.h>
21 #include <linux/platform_device.h>
22 
23 #include <linux/fb.h>
24 #include <linux/init.h>
25 
26     /*
27      *  RAM we reserve for the frame buffer. This defines the maximum screen
28      *  size
29      *
30      *  The default can be overridden if the driver is compiled as a module
31      */
32 
33 #define VIDEOMEMSIZE	(1*1024*1024)	/* 1 MB */
34 
35 static void *videomemory;
36 static u_long videomemorysize = VIDEOMEMSIZE;
37 module_param(videomemorysize, ulong, 0);
38 MODULE_PARM_DESC(videomemorysize, "RAM available to frame buffer (in bytes)");
39 
40 static char *mode_option = NULL;
41 module_param(mode_option, charp, 0);
42 MODULE_PARM_DESC(mode_option, "Preferred video mode (e.g. 640x480-8@60)");
43 
44 static const struct fb_videomode vfb_default = {
45 	.xres =		640,
46 	.yres =		480,
47 	.pixclock =	20000,
48 	.left_margin =	64,
49 	.right_margin =	64,
50 	.upper_margin =	32,
51 	.lower_margin =	32,
52 	.hsync_len =	64,
53 	.vsync_len =	2,
54 	.vmode =	FB_VMODE_NONINTERLACED,
55 };
56 
57 static struct fb_fix_screeninfo vfb_fix = {
58 	.id =		"Virtual FB",
59 	.type =		FB_TYPE_PACKED_PIXELS,
60 	.visual =	FB_VISUAL_PSEUDOCOLOR,
61 	.xpanstep =	1,
62 	.ypanstep =	1,
63 	.ywrapstep =	1,
64 	.accel =	FB_ACCEL_NONE,
65 };
66 
67 static bool vfb_enable __initdata = 0;	/* disabled by default */
68 module_param(vfb_enable, bool, 0);
69 MODULE_PARM_DESC(vfb_enable, "Enable Virtual FB driver");
70 
71 static int vfb_check_var(struct fb_var_screeninfo *var,
72 			 struct fb_info *info);
73 static int vfb_set_par(struct fb_info *info);
74 static int vfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
75 			 u_int transp, struct fb_info *info);
76 static int vfb_pan_display(struct fb_var_screeninfo *var,
77 			   struct fb_info *info);
78 static int vfb_mmap(struct fb_info *info,
79 		    struct vm_area_struct *vma);
80 
81 static struct fb_ops vfb_ops = {
82 	.fb_read        = fb_sys_read,
83 	.fb_write       = fb_sys_write,
84 	.fb_check_var	= vfb_check_var,
85 	.fb_set_par	= vfb_set_par,
86 	.fb_setcolreg	= vfb_setcolreg,
87 	.fb_pan_display	= vfb_pan_display,
88 	.fb_fillrect	= sys_fillrect,
89 	.fb_copyarea	= sys_copyarea,
90 	.fb_imageblit	= sys_imageblit,
91 	.fb_mmap	= vfb_mmap,
92 };
93 
94     /*
95      *  Internal routines
96      */
97 
98 static u_long get_line_length(int xres_virtual, int bpp)
99 {
100 	u_long length;
101 
102 	length = xres_virtual * bpp;
103 	length = (length + 31) & ~31;
104 	length >>= 3;
105 	return (length);
106 }
107 
108     /*
109      *  Setting the video mode has been split into two parts.
110      *  First part, xxxfb_check_var, must not write anything
111      *  to hardware, it should only verify and adjust var.
112      *  This means it doesn't alter par but it does use hardware
113      *  data from it to check this var.
114      */
115 
116 static int vfb_check_var(struct fb_var_screeninfo *var,
117 			 struct fb_info *info)
118 {
119 	u_long line_length;
120 
121 	/*
122 	 *  FB_VMODE_CONUPDATE and FB_VMODE_SMOOTH_XPAN are equal!
123 	 *  as FB_VMODE_SMOOTH_XPAN is only used internally
124 	 */
125 
126 	if (var->vmode & FB_VMODE_CONUPDATE) {
127 		var->vmode |= FB_VMODE_YWRAP;
128 		var->xoffset = info->var.xoffset;
129 		var->yoffset = info->var.yoffset;
130 	}
131 
132 	/*
133 	 *  Some very basic checks
134 	 */
135 	if (!var->xres)
136 		var->xres = 1;
137 	if (!var->yres)
138 		var->yres = 1;
139 	if (var->xres > var->xres_virtual)
140 		var->xres_virtual = var->xres;
141 	if (var->yres > var->yres_virtual)
142 		var->yres_virtual = var->yres;
143 	if (var->bits_per_pixel <= 1)
144 		var->bits_per_pixel = 1;
145 	else if (var->bits_per_pixel <= 8)
146 		var->bits_per_pixel = 8;
147 	else if (var->bits_per_pixel <= 16)
148 		var->bits_per_pixel = 16;
149 	else if (var->bits_per_pixel <= 24)
150 		var->bits_per_pixel = 24;
151 	else if (var->bits_per_pixel <= 32)
152 		var->bits_per_pixel = 32;
153 	else
154 		return -EINVAL;
155 
156 	if (var->xres_virtual < var->xoffset + var->xres)
157 		var->xres_virtual = var->xoffset + var->xres;
158 	if (var->yres_virtual < var->yoffset + var->yres)
159 		var->yres_virtual = var->yoffset + var->yres;
160 
161 	/*
162 	 *  Memory limit
163 	 */
164 	line_length =
165 	    get_line_length(var->xres_virtual, var->bits_per_pixel);
166 	if (line_length * var->yres_virtual > videomemorysize)
167 		return -ENOMEM;
168 
169 	/*
170 	 * Now that we checked it we alter var. The reason being is that the video
171 	 * mode passed in might not work but slight changes to it might make it
172 	 * work. This way we let the user know what is acceptable.
173 	 */
174 	switch (var->bits_per_pixel) {
175 	case 1:
176 	case 8:
177 		var->red.offset = 0;
178 		var->red.length = 8;
179 		var->green.offset = 0;
180 		var->green.length = 8;
181 		var->blue.offset = 0;
182 		var->blue.length = 8;
183 		var->transp.offset = 0;
184 		var->transp.length = 0;
185 		break;
186 	case 16:		/* RGBA 5551 */
187 		if (var->transp.length) {
188 			var->red.offset = 0;
189 			var->red.length = 5;
190 			var->green.offset = 5;
191 			var->green.length = 5;
192 			var->blue.offset = 10;
193 			var->blue.length = 5;
194 			var->transp.offset = 15;
195 			var->transp.length = 1;
196 		} else {	/* RGB 565 */
197 			var->red.offset = 0;
198 			var->red.length = 5;
199 			var->green.offset = 5;
200 			var->green.length = 6;
201 			var->blue.offset = 11;
202 			var->blue.length = 5;
203 			var->transp.offset = 0;
204 			var->transp.length = 0;
205 		}
206 		break;
207 	case 24:		/* RGB 888 */
208 		var->red.offset = 0;
209 		var->red.length = 8;
210 		var->green.offset = 8;
211 		var->green.length = 8;
212 		var->blue.offset = 16;
213 		var->blue.length = 8;
214 		var->transp.offset = 0;
215 		var->transp.length = 0;
216 		break;
217 	case 32:		/* RGBA 8888 */
218 		var->red.offset = 0;
219 		var->red.length = 8;
220 		var->green.offset = 8;
221 		var->green.length = 8;
222 		var->blue.offset = 16;
223 		var->blue.length = 8;
224 		var->transp.offset = 24;
225 		var->transp.length = 8;
226 		break;
227 	}
228 	var->red.msb_right = 0;
229 	var->green.msb_right = 0;
230 	var->blue.msb_right = 0;
231 	var->transp.msb_right = 0;
232 
233 	return 0;
234 }
235 
236 /* This routine actually sets the video mode. It's in here where we
237  * the hardware state info->par and fix which can be affected by the
238  * change in par. For this driver it doesn't do much.
239  */
240 static int vfb_set_par(struct fb_info *info)
241 {
242 	info->fix.line_length = get_line_length(info->var.xres_virtual,
243 						info->var.bits_per_pixel);
244 	return 0;
245 }
246 
247     /*
248      *  Set a single color register. The values supplied are already
249      *  rounded down to the hardware's capabilities (according to the
250      *  entries in the var structure). Return != 0 for invalid regno.
251      */
252 
253 static int vfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
254 			 u_int transp, struct fb_info *info)
255 {
256 	if (regno >= 256)	/* no. of hw registers */
257 		return 1;
258 	/*
259 	 * Program hardware... do anything you want with transp
260 	 */
261 
262 	/* grayscale works only partially under directcolor */
263 	if (info->var.grayscale) {
264 		/* grayscale = 0.30*R + 0.59*G + 0.11*B */
265 		red = green = blue =
266 		    (red * 77 + green * 151 + blue * 28) >> 8;
267 	}
268 
269 	/* Directcolor:
270 	 *   var->{color}.offset contains start of bitfield
271 	 *   var->{color}.length contains length of bitfield
272 	 *   {hardwarespecific} contains width of RAMDAC
273 	 *   cmap[X] is programmed to (X << red.offset) | (X << green.offset) | (X << blue.offset)
274 	 *   RAMDAC[X] is programmed to (red, green, blue)
275 	 *
276 	 * Pseudocolor:
277 	 *    var->{color}.offset is 0 unless the palette index takes less than
278 	 *                        bits_per_pixel bits and is stored in the upper
279 	 *                        bits of the pixel value
280 	 *    var->{color}.length is set so that 1 << length is the number of available
281 	 *                        palette entries
282 	 *    cmap is not used
283 	 *    RAMDAC[X] is programmed to (red, green, blue)
284 	 *
285 	 * Truecolor:
286 	 *    does not use DAC. Usually 3 are present.
287 	 *    var->{color}.offset contains start of bitfield
288 	 *    var->{color}.length contains length of bitfield
289 	 *    cmap is programmed to (red << red.offset) | (green << green.offset) |
290 	 *                      (blue << blue.offset) | (transp << transp.offset)
291 	 *    RAMDAC does not exist
292 	 */
293 #define CNVT_TOHW(val,width) ((((val)<<(width))+0x7FFF-(val))>>16)
294 	switch (info->fix.visual) {
295 	case FB_VISUAL_TRUECOLOR:
296 	case FB_VISUAL_PSEUDOCOLOR:
297 		red = CNVT_TOHW(red, info->var.red.length);
298 		green = CNVT_TOHW(green, info->var.green.length);
299 		blue = CNVT_TOHW(blue, info->var.blue.length);
300 		transp = CNVT_TOHW(transp, info->var.transp.length);
301 		break;
302 	case FB_VISUAL_DIRECTCOLOR:
303 		red = CNVT_TOHW(red, 8);	/* expect 8 bit DAC */
304 		green = CNVT_TOHW(green, 8);
305 		blue = CNVT_TOHW(blue, 8);
306 		/* hey, there is bug in transp handling... */
307 		transp = CNVT_TOHW(transp, 8);
308 		break;
309 	}
310 #undef CNVT_TOHW
311 	/* Truecolor has hardware independent palette */
312 	if (info->fix.visual == FB_VISUAL_TRUECOLOR) {
313 		u32 v;
314 
315 		if (regno >= 16)
316 			return 1;
317 
318 		v = (red << info->var.red.offset) |
319 		    (green << info->var.green.offset) |
320 		    (blue << info->var.blue.offset) |
321 		    (transp << info->var.transp.offset);
322 		switch (info->var.bits_per_pixel) {
323 		case 8:
324 			break;
325 		case 16:
326 			((u32 *) (info->pseudo_palette))[regno] = v;
327 			break;
328 		case 24:
329 		case 32:
330 			((u32 *) (info->pseudo_palette))[regno] = v;
331 			break;
332 		}
333 		return 0;
334 	}
335 	return 0;
336 }
337 
338     /*
339      *  Pan or Wrap the Display
340      *
341      *  This call looks only at xoffset, yoffset and the FB_VMODE_YWRAP flag
342      */
343 
344 static int vfb_pan_display(struct fb_var_screeninfo *var,
345 			   struct fb_info *info)
346 {
347 	if (var->vmode & FB_VMODE_YWRAP) {
348 		if (var->yoffset >= info->var.yres_virtual ||
349 		    var->xoffset)
350 			return -EINVAL;
351 	} else {
352 		if (var->xoffset + info->var.xres > info->var.xres_virtual ||
353 		    var->yoffset + info->var.yres > info->var.yres_virtual)
354 			return -EINVAL;
355 	}
356 	info->var.xoffset = var->xoffset;
357 	info->var.yoffset = var->yoffset;
358 	if (var->vmode & FB_VMODE_YWRAP)
359 		info->var.vmode |= FB_VMODE_YWRAP;
360 	else
361 		info->var.vmode &= ~FB_VMODE_YWRAP;
362 	return 0;
363 }
364 
365     /*
366      *  Most drivers don't need their own mmap function
367      */
368 
369 static int vfb_mmap(struct fb_info *info,
370 		    struct vm_area_struct *vma)
371 {
372 	return remap_vmalloc_range(vma, (void *)info->fix.smem_start, vma->vm_pgoff);
373 }
374 
375 #ifndef MODULE
376 /*
377  * The virtual framebuffer driver is only enabled if explicitly
378  * requested by passing 'video=vfb:' (or any actual options).
379  */
380 static int __init vfb_setup(char *options)
381 {
382 	char *this_opt;
383 
384 	vfb_enable = 0;
385 
386 	if (!options)
387 		return 1;
388 
389 	vfb_enable = 1;
390 
391 	if (!*options)
392 		return 1;
393 
394 	while ((this_opt = strsep(&options, ",")) != NULL) {
395 		if (!*this_opt)
396 			continue;
397 		/* Test disable for backwards compatibility */
398 		if (!strcmp(this_opt, "disable"))
399 			vfb_enable = 0;
400 		else
401 			mode_option = this_opt;
402 	}
403 	return 1;
404 }
405 #endif  /*  MODULE  */
406 
407     /*
408      *  Initialisation
409      */
410 
411 static int vfb_probe(struct platform_device *dev)
412 {
413 	struct fb_info *info;
414 	unsigned int size = PAGE_ALIGN(videomemorysize);
415 	int retval = -ENOMEM;
416 
417 	/*
418 	 * For real video cards we use ioremap.
419 	 */
420 	if (!(videomemory = vmalloc_32_user(size)))
421 		return retval;
422 
423 	info = framebuffer_alloc(sizeof(u32) * 256, &dev->dev);
424 	if (!info)
425 		goto err;
426 
427 	info->screen_base = (char __iomem *)videomemory;
428 	info->fbops = &vfb_ops;
429 
430 	if (!fb_find_mode(&info->var, info, mode_option,
431 			  NULL, 0, &vfb_default, 8)){
432 		fb_err(info, "Unable to find usable video mode.\n");
433 		retval = -EINVAL;
434 		goto err1;
435 	}
436 
437 	vfb_fix.smem_start = (unsigned long) videomemory;
438 	vfb_fix.smem_len = videomemorysize;
439 	info->fix = vfb_fix;
440 	info->pseudo_palette = info->par;
441 	info->par = NULL;
442 	info->flags = FBINFO_FLAG_DEFAULT;
443 
444 	retval = fb_alloc_cmap(&info->cmap, 256, 0);
445 	if (retval < 0)
446 		goto err1;
447 
448 	retval = register_framebuffer(info);
449 	if (retval < 0)
450 		goto err2;
451 	platform_set_drvdata(dev, info);
452 
453 	fb_info(info, "Virtual frame buffer device, using %ldK of video memory\n",
454 		videomemorysize >> 10);
455 	return 0;
456 err2:
457 	fb_dealloc_cmap(&info->cmap);
458 err1:
459 	framebuffer_release(info);
460 err:
461 	vfree(videomemory);
462 	return retval;
463 }
464 
465 static int vfb_remove(struct platform_device *dev)
466 {
467 	struct fb_info *info = platform_get_drvdata(dev);
468 
469 	if (info) {
470 		unregister_framebuffer(info);
471 		vfree(videomemory);
472 		fb_dealloc_cmap(&info->cmap);
473 		framebuffer_release(info);
474 	}
475 	return 0;
476 }
477 
478 static struct platform_driver vfb_driver = {
479 	.probe	= vfb_probe,
480 	.remove = vfb_remove,
481 	.driver = {
482 		.name	= "vfb",
483 	},
484 };
485 
486 static struct platform_device *vfb_device;
487 
488 static int __init vfb_init(void)
489 {
490 	int ret = 0;
491 
492 #ifndef MODULE
493 	char *option = NULL;
494 
495 	if (fb_get_options("vfb", &option))
496 		return -ENODEV;
497 	vfb_setup(option);
498 #endif
499 
500 	if (!vfb_enable)
501 		return -ENXIO;
502 
503 	ret = platform_driver_register(&vfb_driver);
504 
505 	if (!ret) {
506 		vfb_device = platform_device_alloc("vfb", 0);
507 
508 		if (vfb_device)
509 			ret = platform_device_add(vfb_device);
510 		else
511 			ret = -ENOMEM;
512 
513 		if (ret) {
514 			platform_device_put(vfb_device);
515 			platform_driver_unregister(&vfb_driver);
516 		}
517 	}
518 
519 	return ret;
520 }
521 
522 module_init(vfb_init);
523 
524 #ifdef MODULE
525 static void __exit vfb_exit(void)
526 {
527 	platform_device_unregister(vfb_device);
528 	platform_driver_unregister(&vfb_driver);
529 }
530 
531 module_exit(vfb_exit);
532 
533 MODULE_LICENSE("GPL");
534 #endif				/* MODULE */
535