xref: /linux/drivers/video/fbdev/vfb.c (revision 2697b79a469b68e3ad3640f55284359c1396278d) 
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 const struct fb_ops vfb_ops = {
82 	.owner		= THIS_MODULE,
83 	__FB_DEFAULT_SYSMEM_OPS_RDWR,
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_DEFAULT_SYSMEM_OPS_DRAW,
89 	.fb_mmap	= vfb_mmap,
90 };
91 
92     /*
93      *  Internal routines
94      */
95 
96 static u_long get_line_length(int xres_virtual, int bpp)
97 {
98 	u_long length;
99 
100 	length = xres_virtual * bpp;
101 	length = (length + 31) & ~31;
102 	length >>= 3;
103 	return (length);
104 }
105 
106     /*
107      *  Setting the video mode has been split into two parts.
108      *  First part, xxxfb_check_var, must not write anything
109      *  to hardware, it should only verify and adjust var.
110      *  This means it doesn't alter par but it does use hardware
111      *  data from it to check this var.
112      */
113 
114 static int vfb_check_var(struct fb_var_screeninfo *var,
115 			 struct fb_info *info)
116 {
117 	u_long line_length;
118 
119 	/*
120 	 *  FB_VMODE_CONUPDATE and FB_VMODE_SMOOTH_XPAN are equal!
121 	 *  as FB_VMODE_SMOOTH_XPAN is only used internally
122 	 */
123 
124 	if (var->vmode & FB_VMODE_CONUPDATE) {
125 		var->vmode |= FB_VMODE_YWRAP;
126 		var->xoffset = info->var.xoffset;
127 		var->yoffset = info->var.yoffset;
128 	}
129 
130 	/*
131 	 *  Some very basic checks
132 	 */
133 	if (!var->xres)
134 		var->xres = 1;
135 	if (!var->yres)
136 		var->yres = 1;
137 	if (var->xres > var->xres_virtual)
138 		var->xres_virtual = var->xres;
139 	if (var->yres > var->yres_virtual)
140 		var->yres_virtual = var->yres;
141 	if (var->bits_per_pixel <= 1)
142 		var->bits_per_pixel = 1;
143 	else if (var->bits_per_pixel <= 8)
144 		var->bits_per_pixel = 8;
145 	else if (var->bits_per_pixel <= 16)
146 		var->bits_per_pixel = 16;
147 	else if (var->bits_per_pixel <= 24)
148 		var->bits_per_pixel = 24;
149 	else if (var->bits_per_pixel <= 32)
150 		var->bits_per_pixel = 32;
151 	else
152 		return -EINVAL;
153 
154 	if (var->xres_virtual < var->xoffset + var->xres)
155 		var->xres_virtual = var->xoffset + var->xres;
156 	if (var->yres_virtual < var->yoffset + var->yres)
157 		var->yres_virtual = var->yoffset + var->yres;
158 
159 	/*
160 	 *  Memory limit
161 	 */
162 	line_length =
163 	    get_line_length(var->xres_virtual, var->bits_per_pixel);
164 	if (line_length * var->yres_virtual > videomemorysize)
165 		return -ENOMEM;
166 
167 	/*
168 	 * Now that we checked it we alter var. The reason being is that the video
169 	 * mode passed in might not work but slight changes to it might make it
170 	 * work. This way we let the user know what is acceptable.
171 	 */
172 	switch (var->bits_per_pixel) {
173 	case 1:
174 	case 8:
175 		var->red.offset = 0;
176 		var->red.length = 8;
177 		var->green.offset = 0;
178 		var->green.length = 8;
179 		var->blue.offset = 0;
180 		var->blue.length = 8;
181 		var->transp.offset = 0;
182 		var->transp.length = 0;
183 		break;
184 	case 16:		/* RGBA 5551 */
185 		if (var->transp.length) {
186 			var->red.offset = 0;
187 			var->red.length = 5;
188 			var->green.offset = 5;
189 			var->green.length = 5;
190 			var->blue.offset = 10;
191 			var->blue.length = 5;
192 			var->transp.offset = 15;
193 			var->transp.length = 1;
194 		} else {	/* RGB 565 */
195 			var->red.offset = 0;
196 			var->red.length = 5;
197 			var->green.offset = 5;
198 			var->green.length = 6;
199 			var->blue.offset = 11;
200 			var->blue.length = 5;
201 			var->transp.offset = 0;
202 			var->transp.length = 0;
203 		}
204 		break;
205 	case 24:		/* RGB 888 */
206 		var->red.offset = 0;
207 		var->red.length = 8;
208 		var->green.offset = 8;
209 		var->green.length = 8;
210 		var->blue.offset = 16;
211 		var->blue.length = 8;
212 		var->transp.offset = 0;
213 		var->transp.length = 0;
214 		break;
215 	case 32:		/* RGBA 8888 */
216 		var->red.offset = 0;
217 		var->red.length = 8;
218 		var->green.offset = 8;
219 		var->green.length = 8;
220 		var->blue.offset = 16;
221 		var->blue.length = 8;
222 		var->transp.offset = 24;
223 		var->transp.length = 8;
224 		break;
225 	}
226 	var->red.msb_right = 0;
227 	var->green.msb_right = 0;
228 	var->blue.msb_right = 0;
229 	var->transp.msb_right = 0;
230 
231 	return 0;
232 }
233 
234 /* This routine actually sets the video mode. It's in here where we
235  * the hardware state info->par and fix which can be affected by the
236  * change in par. For this driver it doesn't do much.
237  */
238 static int vfb_set_par(struct fb_info *info)
239 {
240 	switch (info->var.bits_per_pixel) {
241 	case 1:
242 		info->fix.visual = FB_VISUAL_MONO01;
243 		break;
244 	case 8:
245 		info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
246 		break;
247 	case 16:
248 	case 24:
249 	case 32:
250 		info->fix.visual = FB_VISUAL_TRUECOLOR;
251 		break;
252 	}
253 
254 	info->fix.line_length = get_line_length(info->var.xres_virtual,
255 						info->var.bits_per_pixel);
256 
257 	return 0;
258 }
259 
260     /*
261      *  Set a single color register. The values supplied are already
262      *  rounded down to the hardware's capabilities (according to the
263      *  entries in the var structure). Return != 0 for invalid regno.
264      */
265 
266 static int vfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
267 			 u_int transp, struct fb_info *info)
268 {
269 	if (regno >= 256)	/* no. of hw registers */
270 		return 1;
271 	/*
272 	 * Program hardware... do anything you want with transp
273 	 */
274 
275 	/* grayscale works only partially under directcolor */
276 	if (info->var.grayscale) {
277 		/* grayscale = 0.30*R + 0.59*G + 0.11*B */
278 		red = green = blue =
279 		    (red * 77 + green * 151 + blue * 28) >> 8;
280 	}
281 
282 	/* Directcolor:
283 	 *   var->{color}.offset contains start of bitfield
284 	 *   var->{color}.length contains length of bitfield
285 	 *   {hardwarespecific} contains width of RAMDAC
286 	 *   cmap[X] is programmed to (X << red.offset) | (X << green.offset) | (X << blue.offset)
287 	 *   RAMDAC[X] is programmed to (red, green, blue)
288 	 *
289 	 * Pseudocolor:
290 	 *    var->{color}.offset is 0 unless the palette index takes less than
291 	 *                        bits_per_pixel bits and is stored in the upper
292 	 *                        bits of the pixel value
293 	 *    var->{color}.length is set so that 1 << length is the number of available
294 	 *                        palette entries
295 	 *    cmap is not used
296 	 *    RAMDAC[X] is programmed to (red, green, blue)
297 	 *
298 	 * Truecolor:
299 	 *    does not use DAC. Usually 3 are present.
300 	 *    var->{color}.offset contains start of bitfield
301 	 *    var->{color}.length contains length of bitfield
302 	 *    cmap is programmed to (red << red.offset) | (green << green.offset) |
303 	 *                      (blue << blue.offset) | (transp << transp.offset)
304 	 *    RAMDAC does not exist
305 	 */
306 #define CNVT_TOHW(val,width) ((((val)<<(width))+0x7FFF-(val))>>16)
307 	switch (info->fix.visual) {
308 	case FB_VISUAL_TRUECOLOR:
309 	case FB_VISUAL_PSEUDOCOLOR:
310 		red = CNVT_TOHW(red, info->var.red.length);
311 		green = CNVT_TOHW(green, info->var.green.length);
312 		blue = CNVT_TOHW(blue, info->var.blue.length);
313 		transp = CNVT_TOHW(transp, info->var.transp.length);
314 		break;
315 	case FB_VISUAL_DIRECTCOLOR:
316 		red = CNVT_TOHW(red, 8);	/* expect 8 bit DAC */
317 		green = CNVT_TOHW(green, 8);
318 		blue = CNVT_TOHW(blue, 8);
319 		/* hey, there is bug in transp handling... */
320 		transp = CNVT_TOHW(transp, 8);
321 		break;
322 	}
323 #undef CNVT_TOHW
324 	/* Truecolor has hardware independent palette */
325 	if (info->fix.visual == FB_VISUAL_TRUECOLOR) {
326 		u32 v;
327 
328 		if (regno >= 16)
329 			return 1;
330 
331 		v = (red << info->var.red.offset) |
332 		    (green << info->var.green.offset) |
333 		    (blue << info->var.blue.offset) |
334 		    (transp << info->var.transp.offset);
335 		switch (info->var.bits_per_pixel) {
336 		case 8:
337 			break;
338 		case 16:
339 			((u32 *) (info->pseudo_palette))[regno] = v;
340 			break;
341 		case 24:
342 		case 32:
343 			((u32 *) (info->pseudo_palette))[regno] = v;
344 			break;
345 		}
346 		return 0;
347 	}
348 	return 0;
349 }
350 
351     /*
352      *  Pan or Wrap the Display
353      *
354      *  This call looks only at xoffset, yoffset and the FB_VMODE_YWRAP flag
355      */
356 
357 static int vfb_pan_display(struct fb_var_screeninfo *var,
358 			   struct fb_info *info)
359 {
360 	if (var->vmode & FB_VMODE_YWRAP) {
361 		if (var->yoffset >= info->var.yres_virtual ||
362 		    var->xoffset)
363 			return -EINVAL;
364 	} else {
365 		if (var->xoffset + info->var.xres > info->var.xres_virtual ||
366 		    var->yoffset + info->var.yres > info->var.yres_virtual)
367 			return -EINVAL;
368 	}
369 	info->var.xoffset = var->xoffset;
370 	info->var.yoffset = var->yoffset;
371 	if (var->vmode & FB_VMODE_YWRAP)
372 		info->var.vmode |= FB_VMODE_YWRAP;
373 	else
374 		info->var.vmode &= ~FB_VMODE_YWRAP;
375 	return 0;
376 }
377 
378     /*
379      *  Most drivers don't need their own mmap function
380      */
381 
382 static int vfb_mmap(struct fb_info *info,
383 		    struct vm_area_struct *vma)
384 {
385 	vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
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->flags |= FBINFO_VIRTFB;
443 	info->screen_buffer = videomemory;
444 	info->fbops = &vfb_ops;
445 
446 	if (!fb_find_mode(&info->var, info, mode_option,
447 			  NULL, 0, &vfb_default, 8)){
448 		fb_err(info, "Unable to find usable video mode.\n");
449 		retval = -EINVAL;
450 		goto err1;
451 	}
452 
453 	vfb_fix.smem_start = (unsigned long) videomemory;
454 	vfb_fix.smem_len = videomemorysize;
455 	info->fix = vfb_fix;
456 	info->pseudo_palette = info->par;
457 	info->par = NULL;
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 void 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 }
493 
494 static struct platform_driver vfb_driver = {
495 	.probe	= vfb_probe,
496 	.remove_new = vfb_remove,
497 	.driver = {
498 		.name	= "vfb",
499 	},
500 };
501 
502 static struct platform_device *vfb_device;
503 
504 static int __init vfb_init(void)
505 {
506 	int ret = 0;
507 
508 #ifndef MODULE
509 	char *option = NULL;
510 
511 	if (fb_get_options("vfb", &option))
512 		return -ENODEV;
513 	vfb_setup(option);
514 #endif
515 
516 	if (!vfb_enable)
517 		return -ENXIO;
518 
519 	ret = platform_driver_register(&vfb_driver);
520 
521 	if (!ret) {
522 		vfb_device = platform_device_alloc("vfb", 0);
523 
524 		if (vfb_device)
525 			ret = platform_device_add(vfb_device);
526 		else
527 			ret = -ENOMEM;
528 
529 		if (ret) {
530 			platform_device_put(vfb_device);
531 			platform_driver_unregister(&vfb_driver);
532 		}
533 	}
534 
535 	return ret;
536 }
537 
538 module_init(vfb_init);
539 
540 #ifdef MODULE
541 static void __exit vfb_exit(void)
542 {
543 	platform_device_unregister(vfb_device);
544 	platform_driver_unregister(&vfb_driver);
545 }
546 
547 module_exit(vfb_exit);
548 
549 MODULE_LICENSE("GPL");
550 #endif				/* MODULE */
551