xref: /linux/drivers/video/fbdev/vfb.c (revision e21f9e2e862e9eb3dd64eaddb6256b3e5098660f) 
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 	switch (info->var.bits_per_pixel) {
243 	case 1:
244 		info->fix.visual = FB_VISUAL_MONO01;
245 		break;
246 	case 8:
247 		info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
248 		break;
249 	case 16:
250 	case 24:
251 	case 32:
252 		info->fix.visual = FB_VISUAL_TRUECOLOR;
253 		break;
254 	}
255 
256 	info->fix.line_length = get_line_length(info->var.xres_virtual,
257 						info->var.bits_per_pixel);
258 
259 	return 0;
260 }
261 
262     /*
263      *  Set a single color register. The values supplied are already
264      *  rounded down to the hardware's capabilities (according to the
265      *  entries in the var structure). Return != 0 for invalid regno.
266      */
267 
268 static int vfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
269 			 u_int transp, struct fb_info *info)
270 {
271 	if (regno >= 256)	/* no. of hw registers */
272 		return 1;
273 	/*
274 	 * Program hardware... do anything you want with transp
275 	 */
276 
277 	/* grayscale works only partially under directcolor */
278 	if (info->var.grayscale) {
279 		/* grayscale = 0.30*R + 0.59*G + 0.11*B */
280 		red = green = blue =
281 		    (red * 77 + green * 151 + blue * 28) >> 8;
282 	}
283 
284 	/* Directcolor:
285 	 *   var->{color}.offset contains start of bitfield
286 	 *   var->{color}.length contains length of bitfield
287 	 *   {hardwarespecific} contains width of RAMDAC
288 	 *   cmap[X] is programmed to (X << red.offset) | (X << green.offset) | (X << blue.offset)
289 	 *   RAMDAC[X] is programmed to (red, green, blue)
290 	 *
291 	 * Pseudocolor:
292 	 *    var->{color}.offset is 0 unless the palette index takes less than
293 	 *                        bits_per_pixel bits and is stored in the upper
294 	 *                        bits of the pixel value
295 	 *    var->{color}.length is set so that 1 << length is the number of available
296 	 *                        palette entries
297 	 *    cmap is not used
298 	 *    RAMDAC[X] is programmed to (red, green, blue)
299 	 *
300 	 * Truecolor:
301 	 *    does not use DAC. Usually 3 are present.
302 	 *    var->{color}.offset contains start of bitfield
303 	 *    var->{color}.length contains length of bitfield
304 	 *    cmap is programmed to (red << red.offset) | (green << green.offset) |
305 	 *                      (blue << blue.offset) | (transp << transp.offset)
306 	 *    RAMDAC does not exist
307 	 */
308 #define CNVT_TOHW(val,width) ((((val)<<(width))+0x7FFF-(val))>>16)
309 	switch (info->fix.visual) {
310 	case FB_VISUAL_TRUECOLOR:
311 	case FB_VISUAL_PSEUDOCOLOR:
312 		red = CNVT_TOHW(red, info->var.red.length);
313 		green = CNVT_TOHW(green, info->var.green.length);
314 		blue = CNVT_TOHW(blue, info->var.blue.length);
315 		transp = CNVT_TOHW(transp, info->var.transp.length);
316 		break;
317 	case FB_VISUAL_DIRECTCOLOR:
318 		red = CNVT_TOHW(red, 8);	/* expect 8 bit DAC */
319 		green = CNVT_TOHW(green, 8);
320 		blue = CNVT_TOHW(blue, 8);
321 		/* hey, there is bug in transp handling... */
322 		transp = CNVT_TOHW(transp, 8);
323 		break;
324 	}
325 #undef CNVT_TOHW
326 	/* Truecolor has hardware independent palette */
327 	if (info->fix.visual == FB_VISUAL_TRUECOLOR) {
328 		u32 v;
329 
330 		if (regno >= 16)
331 			return 1;
332 
333 		v = (red << info->var.red.offset) |
334 		    (green << info->var.green.offset) |
335 		    (blue << info->var.blue.offset) |
336 		    (transp << info->var.transp.offset);
337 		switch (info->var.bits_per_pixel) {
338 		case 8:
339 			break;
340 		case 16:
341 			((u32 *) (info->pseudo_palette))[regno] = v;
342 			break;
343 		case 24:
344 		case 32:
345 			((u32 *) (info->pseudo_palette))[regno] = v;
346 			break;
347 		}
348 		return 0;
349 	}
350 	return 0;
351 }
352 
353     /*
354      *  Pan or Wrap the Display
355      *
356      *  This call looks only at xoffset, yoffset and the FB_VMODE_YWRAP flag
357      */
358 
359 static int vfb_pan_display(struct fb_var_screeninfo *var,
360 			   struct fb_info *info)
361 {
362 	if (var->vmode & FB_VMODE_YWRAP) {
363 		if (var->yoffset >= info->var.yres_virtual ||
364 		    var->xoffset)
365 			return -EINVAL;
366 	} else {
367 		if (var->xoffset + info->var.xres > info->var.xres_virtual ||
368 		    var->yoffset + info->var.yres > info->var.yres_virtual)
369 			return -EINVAL;
370 	}
371 	info->var.xoffset = var->xoffset;
372 	info->var.yoffset = var->yoffset;
373 	if (var->vmode & FB_VMODE_YWRAP)
374 		info->var.vmode |= FB_VMODE_YWRAP;
375 	else
376 		info->var.vmode &= ~FB_VMODE_YWRAP;
377 	return 0;
378 }
379 
380     /*
381      *  Most drivers don't need their own mmap function
382      */
383 
384 static int vfb_mmap(struct fb_info *info,
385 		    struct vm_area_struct *vma)
386 {
387 	return remap_vmalloc_range(vma, (void *)info->fix.smem_start, vma->vm_pgoff);
388 }
389 
390 #ifndef MODULE
391 /*
392  * The virtual framebuffer driver is only enabled if explicitly
393  * requested by passing 'video=vfb:' (or any actual options).
394  */
395 static int __init vfb_setup(char *options)
396 {
397 	char *this_opt;
398 
399 	vfb_enable = 0;
400 
401 	if (!options)
402 		return 1;
403 
404 	vfb_enable = 1;
405 
406 	if (!*options)
407 		return 1;
408 
409 	while ((this_opt = strsep(&options, ",")) != NULL) {
410 		if (!*this_opt)
411 			continue;
412 		/* Test disable for backwards compatibility */
413 		if (!strcmp(this_opt, "disable"))
414 			vfb_enable = 0;
415 		else
416 			mode_option = this_opt;
417 	}
418 	return 1;
419 }
420 #endif  /*  MODULE  */
421 
422     /*
423      *  Initialisation
424      */
425 
426 static int vfb_probe(struct platform_device *dev)
427 {
428 	struct fb_info *info;
429 	unsigned int size = PAGE_ALIGN(videomemorysize);
430 	int retval = -ENOMEM;
431 
432 	/*
433 	 * For real video cards we use ioremap.
434 	 */
435 	if (!(videomemory = vmalloc_32_user(size)))
436 		return retval;
437 
438 	info = framebuffer_alloc(sizeof(u32) * 256, &dev->dev);
439 	if (!info)
440 		goto err;
441 
442 	info->screen_base = (char __iomem *)videomemory;
443 	info->fbops = &vfb_ops;
444 
445 	if (!fb_find_mode(&info->var, info, mode_option,
446 			  NULL, 0, &vfb_default, 8)){
447 		fb_err(info, "Unable to find usable video mode.\n");
448 		retval = -EINVAL;
449 		goto err1;
450 	}
451 
452 	vfb_fix.smem_start = (unsigned long) videomemory;
453 	vfb_fix.smem_len = videomemorysize;
454 	info->fix = vfb_fix;
455 	info->pseudo_palette = info->par;
456 	info->par = NULL;
457 	info->flags = FBINFO_FLAG_DEFAULT;
458 
459 	retval = fb_alloc_cmap(&info->cmap, 256, 0);
460 	if (retval < 0)
461 		goto err1;
462 
463 	retval = register_framebuffer(info);
464 	if (retval < 0)
465 		goto err2;
466 	platform_set_drvdata(dev, info);
467 
468 	vfb_set_par(info);
469 
470 	fb_info(info, "Virtual frame buffer device, using %ldK of video memory\n",
471 		videomemorysize >> 10);
472 	return 0;
473 err2:
474 	fb_dealloc_cmap(&info->cmap);
475 err1:
476 	framebuffer_release(info);
477 err:
478 	vfree(videomemory);
479 	return retval;
480 }
481 
482 static int vfb_remove(struct platform_device *dev)
483 {
484 	struct fb_info *info = platform_get_drvdata(dev);
485 
486 	if (info) {
487 		unregister_framebuffer(info);
488 		vfree(videomemory);
489 		fb_dealloc_cmap(&info->cmap);
490 		framebuffer_release(info);
491 	}
492 	return 0;
493 }
494 
495 static struct platform_driver vfb_driver = {
496 	.probe	= vfb_probe,
497 	.remove = vfb_remove,
498 	.driver = {
499 		.name	= "vfb",
500 	},
501 };
502 
503 static struct platform_device *vfb_device;
504 
505 static int __init vfb_init(void)
506 {
507 	int ret = 0;
508 
509 #ifndef MODULE
510 	char *option = NULL;
511 
512 	if (fb_get_options("vfb", &option))
513 		return -ENODEV;
514 	vfb_setup(option);
515 #endif
516 
517 	if (!vfb_enable)
518 		return -ENXIO;
519 
520 	ret = platform_driver_register(&vfb_driver);
521 
522 	if (!ret) {
523 		vfb_device = platform_device_alloc("vfb", 0);
524 
525 		if (vfb_device)
526 			ret = platform_device_add(vfb_device);
527 		else
528 			ret = -ENOMEM;
529 
530 		if (ret) {
531 			platform_device_put(vfb_device);
532 			platform_driver_unregister(&vfb_driver);
533 		}
534 	}
535 
536 	return ret;
537 }
538 
539 module_init(vfb_init);
540 
541 #ifdef MODULE
542 static void __exit vfb_exit(void)
543 {
544 	platform_device_unregister(vfb_device);
545 	platform_driver_unregister(&vfb_driver);
546 }
547 
548 module_exit(vfb_exit);
549 
550 MODULE_LICENSE("GPL");
551 #endif				/* MODULE */
552