1/*
2 * OpenCores VGA/LCD 2.0 core frame buffer driver
3 *
4 * Copyright (C) 2013 Stefan Kristiansson, stefan.kristiansson@saunalahti.fi
5 *
6 * This file is licensed under the terms of the GNU General Public License
7 * version 2.  This program is licensed "as is" without any warranty of any
8 * kind, whether express or implied.
9 */
10
11#include <linux/delay.h>
12#include <linux/dma-mapping.h>
13#include <linux/errno.h>
14#include <linux/fb.h>
15#include <linux/init.h>
16#include <linux/io.h>
17#include <linux/kernel.h>
18#include <linux/mm.h>
19#include <linux/module.h>
20#include <linux/of.h>
21#include <linux/platform_device.h>
22#include <linux/string.h>
23#include <linux/slab.h>
24
25/* OCFB register defines */
26#define OCFB_CTRL	0x000
27#define OCFB_STAT	0x004
28#define OCFB_HTIM	0x008
29#define OCFB_VTIM	0x00c
30#define OCFB_HVLEN	0x010
31#define OCFB_VBARA	0x014
32#define OCFB_PALETTE	0x800
33
34#define OCFB_CTRL_VEN	0x00000001 /* Video Enable */
35#define OCFB_CTRL_HIE	0x00000002 /* HSync Interrupt Enable */
36#define OCFB_CTRL_PC	0x00000800 /* 8-bit Pseudo Color Enable*/
37#define OCFB_CTRL_CD8	0x00000000 /* Color Depth 8 */
38#define OCFB_CTRL_CD16	0x00000200 /* Color Depth 16 */
39#define OCFB_CTRL_CD24	0x00000400 /* Color Depth 24 */
40#define OCFB_CTRL_CD32	0x00000600 /* Color Depth 32 */
41#define OCFB_CTRL_VBL1	0x00000000 /* Burst Length 1 */
42#define OCFB_CTRL_VBL2	0x00000080 /* Burst Length 2 */
43#define OCFB_CTRL_VBL4	0x00000100 /* Burst Length 4 */
44#define OCFB_CTRL_VBL8	0x00000180 /* Burst Length 8 */
45
46#define PALETTE_SIZE	256
47
48#define OCFB_NAME	"OC VGA/LCD"
49
50static char *mode_option;
51
52static const struct fb_videomode default_mode = {
53	/* 640x480 @ 60 Hz, 31.5 kHz hsync */
54	NULL, 60, 640, 480, 39721, 40, 24, 32, 11, 96, 2,
55	0, FB_VMODE_NONINTERLACED
56};
57
58struct ocfb_dev {
59	struct fb_info info;
60	void __iomem *regs;
61	/* flag indicating whether the regs are little endian accessed */
62	int little_endian;
63	/* Physical and virtual addresses of framebuffer */
64	dma_addr_t fb_phys;
65	void __iomem *fb_virt;
66	u32 pseudo_palette[PALETTE_SIZE];
67};
68
69#ifndef MODULE
70static int __init ocfb_setup(char *options)
71{
72	char *curr_opt;
73
74	if (!options || !*options)
75		return 0;
76
77	while ((curr_opt = strsep(&options, ",")) != NULL) {
78		if (!*curr_opt)
79			continue;
80		mode_option = curr_opt;
81	}
82
83	return 0;
84}
85#endif
86
87static inline u32 ocfb_readreg(struct ocfb_dev *fbdev, loff_t offset)
88{
89	if (fbdev->little_endian)
90		return ioread32(fbdev->regs + offset);
91	else
92		return ioread32be(fbdev->regs + offset);
93}
94
95static void ocfb_writereg(struct ocfb_dev *fbdev, loff_t offset, u32 data)
96{
97	if (fbdev->little_endian)
98		iowrite32(data, fbdev->regs + offset);
99	else
100		iowrite32be(data, fbdev->regs + offset);
101}
102
103static int ocfb_setupfb(struct ocfb_dev *fbdev)
104{
105	unsigned long bpp_config;
106	struct fb_var_screeninfo *var = &fbdev->info.var;
107	struct device *dev = fbdev->info.device;
108	u32 hlen;
109	u32 vlen;
110
111	/* Disable display */
112	ocfb_writereg(fbdev, OCFB_CTRL, 0);
113
114	/* Register framebuffer address */
115	fbdev->little_endian = 0;
116	ocfb_writereg(fbdev, OCFB_VBARA, fbdev->fb_phys);
117
118	/* Detect endianess */
119	if (ocfb_readreg(fbdev, OCFB_VBARA) != fbdev->fb_phys) {
120		fbdev->little_endian = 1;
121		ocfb_writereg(fbdev, OCFB_VBARA, fbdev->fb_phys);
122	}
123
124	/* Horizontal timings */
125	ocfb_writereg(fbdev, OCFB_HTIM, (var->hsync_len - 1) << 24 |
126		      (var->left_margin - 1) << 16 | (var->xres - 1));
127
128	/* Vertical timings */
129	ocfb_writereg(fbdev, OCFB_VTIM, (var->vsync_len - 1) << 24 |
130		      (var->upper_margin - 1) << 16 | (var->yres - 1));
131
132	/* Total length of frame */
133	hlen = var->left_margin + var->right_margin + var->hsync_len +
134		var->xres;
135
136	vlen = var->upper_margin + var->lower_margin + var->vsync_len +
137		var->yres;
138
139	ocfb_writereg(fbdev, OCFB_HVLEN, (hlen - 1) << 16 | (vlen - 1));
140
141	bpp_config = OCFB_CTRL_CD8;
142	switch (var->bits_per_pixel) {
143	case 8:
144		if (!var->grayscale)
145			bpp_config |= OCFB_CTRL_PC;  /* enable palette */
146		break;
147
148	case 16:
149		bpp_config |= OCFB_CTRL_CD16;
150		break;
151
152	case 24:
153		bpp_config |= OCFB_CTRL_CD24;
154		break;
155
156	case 32:
157		bpp_config |= OCFB_CTRL_CD32;
158		break;
159
160	default:
161		dev_err(dev, "no bpp specified\n");
162		break;
163	}
164
165	/* maximum (8) VBL (video memory burst length) */
166	bpp_config |= OCFB_CTRL_VBL8;
167
168	/* Enable output */
169	ocfb_writereg(fbdev, OCFB_CTRL, (OCFB_CTRL_VEN | bpp_config));
170
171	return 0;
172}
173
174static int ocfb_setcolreg(unsigned regno, unsigned red, unsigned green,
175			  unsigned blue, unsigned transp,
176			  struct fb_info *info)
177{
178	struct ocfb_dev *fbdev = (struct ocfb_dev *)info->par;
179	u32 color;
180
181	if (regno >= info->cmap.len) {
182		dev_err(info->device, "regno >= cmap.len\n");
183		return 1;
184	}
185
186	if (info->var.grayscale) {
187		/* grayscale = 0.30*R + 0.59*G + 0.11*B */
188		red = green = blue = (red * 77 + green * 151 + blue * 28) >> 8;
189	}
190
191	red >>= (16 - info->var.red.length);
192	green >>= (16 - info->var.green.length);
193	blue >>= (16 - info->var.blue.length);
194	transp >>= (16 - info->var.transp.length);
195
196	if (info->var.bits_per_pixel == 8 && !info->var.grayscale) {
197		regno <<= 2;
198		color = (red << 16) | (green << 8) | blue;
199		ocfb_writereg(fbdev, OCFB_PALETTE + regno, color);
200	} else {
201		((u32 *)(info->pseudo_palette))[regno] =
202			(red << info->var.red.offset) |
203			(green << info->var.green.offset) |
204			(blue << info->var.blue.offset) |
205			(transp << info->var.transp.offset);
206	}
207
208	return 0;
209}
210
211static int ocfb_init_fix(struct ocfb_dev *fbdev)
212{
213	struct fb_var_screeninfo *var = &fbdev->info.var;
214	struct fb_fix_screeninfo *fix = &fbdev->info.fix;
215
216	strcpy(fix->id, OCFB_NAME);
217
218	fix->line_length = var->xres * var->bits_per_pixel/8;
219	fix->smem_len = fix->line_length * var->yres;
220	fix->type = FB_TYPE_PACKED_PIXELS;
221
222	if (var->bits_per_pixel == 8 && !var->grayscale)
223		fix->visual = FB_VISUAL_PSEUDOCOLOR;
224	else
225		fix->visual = FB_VISUAL_TRUECOLOR;
226
227	return 0;
228}
229
230static int ocfb_init_var(struct ocfb_dev *fbdev)
231{
232	struct fb_var_screeninfo *var = &fbdev->info.var;
233
234	var->accel_flags = FB_ACCEL_NONE;
235	var->activate = FB_ACTIVATE_NOW;
236	var->xres_virtual = var->xres;
237	var->yres_virtual = var->yres;
238
239	switch (var->bits_per_pixel) {
240	case 8:
241		var->transp.offset = 0;
242		var->transp.length = 0;
243		var->red.offset = 0;
244		var->red.length = 8;
245		var->green.offset = 0;
246		var->green.length = 8;
247		var->blue.offset = 0;
248		var->blue.length = 8;
249		break;
250
251	case 16:
252		var->transp.offset = 0;
253		var->transp.length = 0;
254		var->red.offset = 11;
255		var->red.length = 5;
256		var->green.offset = 5;
257		var->green.length = 6;
258		var->blue.offset = 0;
259		var->blue.length  = 5;
260		break;
261
262	case 24:
263		var->transp.offset = 0;
264		var->transp.length = 0;
265		var->red.offset = 16;
266		var->red.length = 8;
267		var->green.offset = 8;
268		var->green.length = 8;
269		var->blue.offset = 0;
270		var->blue.length = 8;
271		break;
272
273	case 32:
274		var->transp.offset = 24;
275		var->transp.length = 8;
276		var->red.offset = 16;
277		var->red.length = 8;
278		var->green.offset = 8;
279		var->green.length = 8;
280		var->blue.offset = 0;
281		var->blue.length = 8;
282		break;
283	}
284
285	return 0;
286}
287
288static const struct fb_ops ocfb_ops = {
289	.owner		= THIS_MODULE,
290	FB_DEFAULT_IOMEM_OPS,
291	.fb_setcolreg	= ocfb_setcolreg,
292};
293
294static int ocfb_probe(struct platform_device *pdev)
295{
296	int ret = 0;
297	struct ocfb_dev *fbdev;
298	int fbsize;
299
300	fbdev = devm_kzalloc(&pdev->dev, sizeof(*fbdev), GFP_KERNEL);
301	if (!fbdev)
302		return -ENOMEM;
303
304	platform_set_drvdata(pdev, fbdev);
305
306	fbdev->info.fbops = &ocfb_ops;
307	fbdev->info.device = &pdev->dev;
308	fbdev->info.par = fbdev;
309
310	/* Video mode setup */
311	if (!fb_find_mode(&fbdev->info.var, &fbdev->info, mode_option,
312			  NULL, 0, &default_mode, 16)) {
313		dev_err(&pdev->dev, "No valid video modes found\n");
314		return -EINVAL;
315	}
316	ocfb_init_var(fbdev);
317	ocfb_init_fix(fbdev);
318
319	fbdev->regs = devm_platform_ioremap_resource(pdev, 0);
320	if (IS_ERR(fbdev->regs))
321		return PTR_ERR(fbdev->regs);
322
323	/* Allocate framebuffer memory */
324	fbsize = fbdev->info.fix.smem_len;
325	fbdev->fb_virt = dma_alloc_coherent(&pdev->dev, PAGE_ALIGN(fbsize),
326					    &fbdev->fb_phys, GFP_KERNEL);
327	if (!fbdev->fb_virt) {
328		dev_err(&pdev->dev,
329			"Frame buffer memory allocation failed\n");
330		return -ENOMEM;
331	}
332	fbdev->info.fix.smem_start = fbdev->fb_phys;
333	fbdev->info.screen_base = fbdev->fb_virt;
334	fbdev->info.pseudo_palette = fbdev->pseudo_palette;
335
336	/* Clear framebuffer */
337	memset_io(fbdev->fb_virt, 0, fbsize);
338
339	/* Setup and enable the framebuffer */
340	ocfb_setupfb(fbdev);
341
342	if (fbdev->little_endian)
343		fbdev->info.flags |= FBINFO_FOREIGN_ENDIAN;
344
345	/* Allocate color map */
346	ret = fb_alloc_cmap(&fbdev->info.cmap, PALETTE_SIZE, 0);
347	if (ret) {
348		dev_err(&pdev->dev, "Color map allocation failed\n");
349		goto err_dma_free;
350	}
351
352	/* Register framebuffer */
353	ret = register_framebuffer(&fbdev->info);
354	if (ret) {
355		dev_err(&pdev->dev, "Framebuffer registration failed\n");
356		goto err_dealloc_cmap;
357	}
358
359	return 0;
360
361err_dealloc_cmap:
362	fb_dealloc_cmap(&fbdev->info.cmap);
363
364err_dma_free:
365	dma_free_coherent(&pdev->dev, PAGE_ALIGN(fbsize), fbdev->fb_virt,
366			  fbdev->fb_phys);
367
368	return ret;
369}
370
371static void ocfb_remove(struct platform_device *pdev)
372{
373	struct ocfb_dev *fbdev = platform_get_drvdata(pdev);
374
375	unregister_framebuffer(&fbdev->info);
376	fb_dealloc_cmap(&fbdev->info.cmap);
377	dma_free_coherent(&pdev->dev, PAGE_ALIGN(fbdev->info.fix.smem_len),
378			  fbdev->fb_virt, fbdev->fb_phys);
379
380	/* Disable display */
381	ocfb_writereg(fbdev, OCFB_CTRL, 0);
382
383	platform_set_drvdata(pdev, NULL);
384}
385
386static const struct of_device_id ocfb_match[] = {
387	{ .compatible = "opencores,ocfb", },
388	{},
389};
390MODULE_DEVICE_TABLE(of, ocfb_match);
391
392static struct platform_driver ocfb_driver = {
393	.probe  = ocfb_probe,
394	.remove_new = ocfb_remove,
395	.driver = {
396		.name = "ocfb_fb",
397		.of_match_table = ocfb_match,
398	}
399};
400
401/*
402 * Init and exit routines
403 */
404static int __init ocfb_init(void)
405{
406#ifndef MODULE
407	char *option = NULL;
408
409	if (fb_get_options("ocfb", &option))
410		return -ENODEV;
411	ocfb_setup(option);
412#endif
413	return platform_driver_register(&ocfb_driver);
414}
415
416static void __exit ocfb_exit(void)
417{
418	platform_driver_unregister(&ocfb_driver);
419}
420
421module_init(ocfb_init);
422module_exit(ocfb_exit);
423
424MODULE_AUTHOR("Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>");
425MODULE_DESCRIPTION("OpenCores VGA/LCD 2.0 frame buffer driver");
426MODULE_LICENSE("GPL v2");
427module_param(mode_option, charp, 0);
428MODULE_PARM_DESC(mode_option, "Video mode ('<xres>x<yres>[-<bpp>][@refresh]')");
429