xref: /kernel/linux/linux-6.6/drivers/video/fbdev/vfb.c (revision 62306a36) 
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
35static void *videomemory;
36static u_long videomemorysize = VIDEOMEMSIZE;
37module_param(videomemorysize, ulong, 0);
38MODULE_PARM_DESC(videomemorysize, "RAM available to frame buffer (in bytes)");
39
40static char *mode_option = NULL;
41module_param(mode_option, charp, 0);
42MODULE_PARM_DESC(mode_option, "Preferred video mode (e.g. 640x480-8@60)");
43
44static 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
57static 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
67static bool vfb_enable __initdata = 0;	/* disabled by default */
68module_param(vfb_enable, bool, 0);
69MODULE_PARM_DESC(vfb_enable, "Enable Virtual FB driver");
70
71static int vfb_check_var(struct fb_var_screeninfo *var,
72			 struct fb_info *info);
73static int vfb_set_par(struct fb_info *info);
74static int vfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
75			 u_int transp, struct fb_info *info);
76static int vfb_pan_display(struct fb_var_screeninfo *var,
77			   struct fb_info *info);
78static int vfb_mmap(struct fb_info *info,
79		    struct vm_area_struct *vma);
80
81static const struct fb_ops vfb_ops = {
82	.owner		= THIS_MODULE,
83	.fb_read        = fb_sys_read,
84	.fb_write       = fb_sys_write,
85	.fb_check_var	= vfb_check_var,
86	.fb_set_par	= vfb_set_par,
87	.fb_setcolreg	= vfb_setcolreg,
88	.fb_pan_display	= vfb_pan_display,
89	.fb_fillrect	= sys_fillrect,
90	.fb_copyarea	= sys_copyarea,
91	.fb_imageblit	= sys_imageblit,
92	.fb_mmap	= vfb_mmap,
93};
94
95    /*
96     *  Internal routines
97     */
98
99static u_long get_line_length(int xres_virtual, int bpp)
100{
101	u_long length;
102
103	length = xres_virtual * bpp;
104	length = (length + 31) & ~31;
105	length >>= 3;
106	return (length);
107}
108
109    /*
110     *  Setting the video mode has been split into two parts.
111     *  First part, xxxfb_check_var, must not write anything
112     *  to hardware, it should only verify and adjust var.
113     *  This means it doesn't alter par but it does use hardware
114     *  data from it to check this var.
115     */
116
117static int vfb_check_var(struct fb_var_screeninfo *var,
118			 struct fb_info *info)
119{
120	u_long line_length;
121
122	/*
123	 *  FB_VMODE_CONUPDATE and FB_VMODE_SMOOTH_XPAN are equal!
124	 *  as FB_VMODE_SMOOTH_XPAN is only used internally
125	 */
126
127	if (var->vmode & FB_VMODE_CONUPDATE) {
128		var->vmode |= FB_VMODE_YWRAP;
129		var->xoffset = info->var.xoffset;
130		var->yoffset = info->var.yoffset;
131	}
132
133	/*
134	 *  Some very basic checks
135	 */
136	if (!var->xres)
137		var->xres = 1;
138	if (!var->yres)
139		var->yres = 1;
140	if (var->xres > var->xres_virtual)
141		var->xres_virtual = var->xres;
142	if (var->yres > var->yres_virtual)
143		var->yres_virtual = var->yres;
144	if (var->bits_per_pixel <= 1)
145		var->bits_per_pixel = 1;
146	else if (var->bits_per_pixel <= 8)
147		var->bits_per_pixel = 8;
148	else if (var->bits_per_pixel <= 16)
149		var->bits_per_pixel = 16;
150	else if (var->bits_per_pixel <= 24)
151		var->bits_per_pixel = 24;
152	else if (var->bits_per_pixel <= 32)
153		var->bits_per_pixel = 32;
154	else
155		return -EINVAL;
156
157	if (var->xres_virtual < var->xoffset + var->xres)
158		var->xres_virtual = var->xoffset + var->xres;
159	if (var->yres_virtual < var->yoffset + var->yres)
160		var->yres_virtual = var->yoffset + var->yres;
161
162	/*
163	 *  Memory limit
164	 */
165	line_length =
166	    get_line_length(var->xres_virtual, var->bits_per_pixel);
167	if (line_length * var->yres_virtual > videomemorysize)
168		return -ENOMEM;
169
170	/*
171	 * Now that we checked it we alter var. The reason being is that the video
172	 * mode passed in might not work but slight changes to it might make it
173	 * work. This way we let the user know what is acceptable.
174	 */
175	switch (var->bits_per_pixel) {
176	case 1:
177	case 8:
178		var->red.offset = 0;
179		var->red.length = 8;
180		var->green.offset = 0;
181		var->green.length = 8;
182		var->blue.offset = 0;
183		var->blue.length = 8;
184		var->transp.offset = 0;
185		var->transp.length = 0;
186		break;
187	case 16:		/* RGBA 5551 */
188		if (var->transp.length) {
189			var->red.offset = 0;
190			var->red.length = 5;
191			var->green.offset = 5;
192			var->green.length = 5;
193			var->blue.offset = 10;
194			var->blue.length = 5;
195			var->transp.offset = 15;
196			var->transp.length = 1;
197		} else {	/* RGB 565 */
198			var->red.offset = 0;
199			var->red.length = 5;
200			var->green.offset = 5;
201			var->green.length = 6;
202			var->blue.offset = 11;
203			var->blue.length = 5;
204			var->transp.offset = 0;
205			var->transp.length = 0;
206		}
207		break;
208	case 24:		/* RGB 888 */
209		var->red.offset = 0;
210		var->red.length = 8;
211		var->green.offset = 8;
212		var->green.length = 8;
213		var->blue.offset = 16;
214		var->blue.length = 8;
215		var->transp.offset = 0;
216		var->transp.length = 0;
217		break;
218	case 32:		/* RGBA 8888 */
219		var->red.offset = 0;
220		var->red.length = 8;
221		var->green.offset = 8;
222		var->green.length = 8;
223		var->blue.offset = 16;
224		var->blue.length = 8;
225		var->transp.offset = 24;
226		var->transp.length = 8;
227		break;
228	}
229	var->red.msb_right = 0;
230	var->green.msb_right = 0;
231	var->blue.msb_right = 0;
232	var->transp.msb_right = 0;
233
234	return 0;
235}
236
237/* This routine actually sets the video mode. It's in here where we
238 * the hardware state info->par and fix which can be affected by the
239 * change in par. For this driver it doesn't do much.
240 */
241static int vfb_set_par(struct fb_info *info)
242{
243	switch (info->var.bits_per_pixel) {
244	case 1:
245		info->fix.visual = FB_VISUAL_MONO01;
246		break;
247	case 8:
248		info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
249		break;
250	case 16:
251	case 24:
252	case 32:
253		info->fix.visual = FB_VISUAL_TRUECOLOR;
254		break;
255	}
256
257	info->fix.line_length = get_line_length(info->var.xres_virtual,
258						info->var.bits_per_pixel);
259
260	return 0;
261}
262
263    /*
264     *  Set a single color register. The values supplied are already
265     *  rounded down to the hardware's capabilities (according to the
266     *  entries in the var structure). Return != 0 for invalid regno.
267     */
268
269static int vfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
270			 u_int transp, struct fb_info *info)
271{
272	if (regno >= 256)	/* no. of hw registers */
273		return 1;
274	/*
275	 * Program hardware... do anything you want with transp
276	 */
277
278	/* grayscale works only partially under directcolor */
279	if (info->var.grayscale) {
280		/* grayscale = 0.30*R + 0.59*G + 0.11*B */
281		red = green = blue =
282		    (red * 77 + green * 151 + blue * 28) >> 8;
283	}
284
285	/* Directcolor:
286	 *   var->{color}.offset contains start of bitfield
287	 *   var->{color}.length contains length of bitfield
288	 *   {hardwarespecific} contains width of RAMDAC
289	 *   cmap[X] is programmed to (X << red.offset) | (X << green.offset) | (X << blue.offset)
290	 *   RAMDAC[X] is programmed to (red, green, blue)
291	 *
292	 * Pseudocolor:
293	 *    var->{color}.offset is 0 unless the palette index takes less than
294	 *                        bits_per_pixel bits and is stored in the upper
295	 *                        bits of the pixel value
296	 *    var->{color}.length is set so that 1 << length is the number of available
297	 *                        palette entries
298	 *    cmap is not used
299	 *    RAMDAC[X] is programmed to (red, green, blue)
300	 *
301	 * Truecolor:
302	 *    does not use DAC. Usually 3 are present.
303	 *    var->{color}.offset contains start of bitfield
304	 *    var->{color}.length contains length of bitfield
305	 *    cmap is programmed to (red << red.offset) | (green << green.offset) |
306	 *                      (blue << blue.offset) | (transp << transp.offset)
307	 *    RAMDAC does not exist
308	 */
309#define CNVT_TOHW(val,width) ((((val)<<(width))+0x7FFF-(val))>>16)
310	switch (info->fix.visual) {
311	case FB_VISUAL_TRUECOLOR:
312	case FB_VISUAL_PSEUDOCOLOR:
313		red = CNVT_TOHW(red, info->var.red.length);
314		green = CNVT_TOHW(green, info->var.green.length);
315		blue = CNVT_TOHW(blue, info->var.blue.length);
316		transp = CNVT_TOHW(transp, info->var.transp.length);
317		break;
318	case FB_VISUAL_DIRECTCOLOR:
319		red = CNVT_TOHW(red, 8);	/* expect 8 bit DAC */
320		green = CNVT_TOHW(green, 8);
321		blue = CNVT_TOHW(blue, 8);
322		/* hey, there is bug in transp handling... */
323		transp = CNVT_TOHW(transp, 8);
324		break;
325	}
326#undef CNVT_TOHW
327	/* Truecolor has hardware independent palette */
328	if (info->fix.visual == FB_VISUAL_TRUECOLOR) {
329		u32 v;
330
331		if (regno >= 16)
332			return 1;
333
334		v = (red << info->var.red.offset) |
335		    (green << info->var.green.offset) |
336		    (blue << info->var.blue.offset) |
337		    (transp << info->var.transp.offset);
338		switch (info->var.bits_per_pixel) {
339		case 8:
340			break;
341		case 16:
342			((u32 *) (info->pseudo_palette))[regno] = v;
343			break;
344		case 24:
345		case 32:
346			((u32 *) (info->pseudo_palette))[regno] = v;
347			break;
348		}
349		return 0;
350	}
351	return 0;
352}
353
354    /*
355     *  Pan or Wrap the Display
356     *
357     *  This call looks only at xoffset, yoffset and the FB_VMODE_YWRAP flag
358     */
359
360static int vfb_pan_display(struct fb_var_screeninfo *var,
361			   struct fb_info *info)
362{
363	if (var->vmode & FB_VMODE_YWRAP) {
364		if (var->yoffset >= info->var.yres_virtual ||
365		    var->xoffset)
366			return -EINVAL;
367	} else {
368		if (var->xoffset + info->var.xres > info->var.xres_virtual ||
369		    var->yoffset + info->var.yres > info->var.yres_virtual)
370			return -EINVAL;
371	}
372	info->var.xoffset = var->xoffset;
373	info->var.yoffset = var->yoffset;
374	if (var->vmode & FB_VMODE_YWRAP)
375		info->var.vmode |= FB_VMODE_YWRAP;
376	else
377		info->var.vmode &= ~FB_VMODE_YWRAP;
378	return 0;
379}
380
381    /*
382     *  Most drivers don't need their own mmap function
383     */
384
385static int vfb_mmap(struct fb_info *info,
386		    struct vm_area_struct *vma)
387{
388	return remap_vmalloc_range(vma, (void *)info->fix.smem_start, vma->vm_pgoff);
389}
390
391#ifndef MODULE
392/*
393 * The virtual framebuffer driver is only enabled if explicitly
394 * requested by passing 'video=vfb:' (or any actual options).
395 */
396static int __init vfb_setup(char *options)
397{
398	char *this_opt;
399
400	vfb_enable = 0;
401
402	if (!options)
403		return 1;
404
405	vfb_enable = 1;
406
407	if (!*options)
408		return 1;
409
410	while ((this_opt = strsep(&options, ",")) != NULL) {
411		if (!*this_opt)
412			continue;
413		/* Test disable for backwards compatibility */
414		if (!strcmp(this_opt, "disable"))
415			vfb_enable = 0;
416		else
417			mode_option = this_opt;
418	}
419	return 1;
420}
421#endif  /*  MODULE  */
422
423    /*
424     *  Initialisation
425     */
426
427static int vfb_probe(struct platform_device *dev)
428{
429	struct fb_info *info;
430	unsigned int size = PAGE_ALIGN(videomemorysize);
431	int retval = -ENOMEM;
432
433	/*
434	 * For real video cards we use ioremap.
435	 */
436	if (!(videomemory = vmalloc_32_user(size)))
437		return retval;
438
439	info = framebuffer_alloc(sizeof(u32) * 256, &dev->dev);
440	if (!info)
441		goto err;
442
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;
473err2:
474	fb_dealloc_cmap(&info->cmap);
475err1:
476	framebuffer_release(info);
477err:
478	vfree(videomemory);
479	return retval;
480}
481
482static 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
494static struct platform_driver vfb_driver = {
495	.probe	= vfb_probe,
496	.remove_new = vfb_remove,
497	.driver = {
498		.name	= "vfb",
499	},
500};
501
502static struct platform_device *vfb_device;
503
504static 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
538module_init(vfb_init);
539
540#ifdef MODULE
541static void __exit vfb_exit(void)
542{
543	platform_device_unregister(vfb_device);
544	platform_driver_unregister(&vfb_driver);
545}
546
547module_exit(vfb_exit);
548
549MODULE_LICENSE("GPL");
550#endif				/* MODULE */
551