1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *  Cobalt/SEAD3 LCD frame buffer driver.
4 *
5 *  Copyright (C) 2008  Yoichi Yuasa <yuasa@linux-mips.org>
6 *  Copyright (C) 2012  MIPS Technologies, Inc.
7 */
8#include <linux/delay.h>
9#include <linux/fb.h>
10#include <linux/init.h>
11#include <linux/io.h>
12#include <linux/ioport.h>
13#include <linux/uaccess.h>
14#include <linux/platform_device.h>
15#include <linux/module.h>
16#include <linux/sched/signal.h>
17
18/*
19 * Cursor position address
20 * \X  0    1    2  ...  14   15
21 * Y+----+----+----+---+----+----+
22 * 0|0x00|0x01|0x02|...|0x0e|0x0f|
23 *  +----+----+----+---+----+----+
24 * 1|0x40|0x41|0x42|...|0x4e|0x4f|
25 *  +----+----+----+---+----+----+
26 */
27#define LCD_DATA_REG_OFFSET	0x10
28#define LCD_XRES_MAX		16
29#define LCD_YRES_MAX		2
30#define LCD_CHARS_MAX		32
31
32#define LCD_CLEAR		0x01
33#define LCD_CURSOR_MOVE_HOME	0x02
34#define LCD_RESET		0x06
35#define LCD_OFF			0x08
36#define LCD_CURSOR_OFF		0x0c
37#define LCD_CURSOR_BLINK_OFF	0x0e
38#define LCD_CURSOR_ON		0x0f
39#define LCD_ON			LCD_CURSOR_ON
40#define LCD_CURSOR_MOVE_LEFT	0x10
41#define LCD_CURSOR_MOVE_RIGHT	0x14
42#define LCD_DISPLAY_LEFT	0x18
43#define LCD_DISPLAY_RIGHT	0x1c
44#define LCD_PRERESET		0x3f	/* execute 4 times continuously */
45#define LCD_BUSY		0x80
46
47#define LCD_GRAPHIC_MODE	0x40
48#define LCD_TEXT_MODE		0x80
49#define LCD_CUR_POS_MASK	0x7f
50
51#define LCD_CUR_POS(x)		((x) & LCD_CUR_POS_MASK)
52#define LCD_TEXT_POS(x)		((x) | LCD_TEXT_MODE)
53
54static inline void lcd_write_control(struct fb_info *info, u8 control)
55{
56	writel((u32)control << 24, info->screen_base);
57}
58
59static inline u8 lcd_read_control(struct fb_info *info)
60{
61	return readl(info->screen_base) >> 24;
62}
63
64static inline void lcd_write_data(struct fb_info *info, u8 data)
65{
66	writel((u32)data << 24, info->screen_base + LCD_DATA_REG_OFFSET);
67}
68
69static inline u8 lcd_read_data(struct fb_info *info)
70{
71	return readl(info->screen_base + LCD_DATA_REG_OFFSET) >> 24;
72}
73
74static int lcd_busy_wait(struct fb_info *info)
75{
76	u8 val = 0;
77	int timeout = 10, retval = 0;
78
79	do {
80		val = lcd_read_control(info);
81		val &= LCD_BUSY;
82		if (val != LCD_BUSY)
83			break;
84
85		if (msleep_interruptible(1))
86			return -EINTR;
87
88		timeout--;
89	} while (timeout);
90
91	if (val == LCD_BUSY)
92		retval = -EBUSY;
93
94	return retval;
95}
96
97static void lcd_clear(struct fb_info *info)
98{
99	int i;
100
101	for (i = 0; i < 4; i++) {
102		udelay(150);
103
104		lcd_write_control(info, LCD_PRERESET);
105	}
106
107	udelay(150);
108
109	lcd_write_control(info, LCD_CLEAR);
110
111	udelay(150);
112
113	lcd_write_control(info, LCD_RESET);
114}
115
116static const struct fb_fix_screeninfo cobalt_lcdfb_fix = {
117	.id		= "cobalt-lcd",
118	.type		= FB_TYPE_TEXT,
119	.type_aux	= FB_AUX_TEXT_MDA,
120	.visual		= FB_VISUAL_MONO01,
121	.line_length	= LCD_XRES_MAX,
122	.accel		= FB_ACCEL_NONE,
123};
124
125static ssize_t cobalt_lcdfb_read(struct fb_info *info, char __user *buf,
126				 size_t count, loff_t *ppos)
127{
128	char src[LCD_CHARS_MAX];
129	unsigned long pos;
130	int len, retval = 0;
131
132	if (!info->screen_base)
133		return -ENODEV;
134
135	pos = *ppos;
136	if (pos >= LCD_CHARS_MAX || count == 0)
137		return 0;
138
139	if (count > LCD_CHARS_MAX)
140		count = LCD_CHARS_MAX;
141
142	if (pos + count > LCD_CHARS_MAX)
143		count = LCD_CHARS_MAX - pos;
144
145	for (len = 0; len < count; len++) {
146		retval = lcd_busy_wait(info);
147		if (retval < 0)
148			break;
149
150		lcd_write_control(info, LCD_TEXT_POS(pos));
151
152		retval = lcd_busy_wait(info);
153		if (retval < 0)
154			break;
155
156		src[len] = lcd_read_data(info);
157		if (pos == 0x0f)
158			pos = 0x40;
159		else
160			pos++;
161	}
162
163	if (retval < 0 && signal_pending(current))
164		return -ERESTARTSYS;
165
166	if (copy_to_user(buf, src, len))
167		return -EFAULT;
168
169	*ppos += len;
170
171	return len;
172}
173
174static ssize_t cobalt_lcdfb_write(struct fb_info *info, const char __user *buf,
175				  size_t count, loff_t *ppos)
176{
177	char dst[LCD_CHARS_MAX];
178	unsigned long pos;
179	int len, retval = 0;
180
181	if (!info->screen_base)
182		return -ENODEV;
183
184	pos = *ppos;
185	if (pos >= LCD_CHARS_MAX || count == 0)
186		return 0;
187
188	if (count > LCD_CHARS_MAX)
189		count = LCD_CHARS_MAX;
190
191	if (pos + count > LCD_CHARS_MAX)
192		count = LCD_CHARS_MAX - pos;
193
194	if (copy_from_user(dst, buf, count))
195		return -EFAULT;
196
197	for (len = 0; len < count; len++) {
198		retval = lcd_busy_wait(info);
199		if (retval < 0)
200			break;
201
202		lcd_write_control(info, LCD_TEXT_POS(pos));
203
204		retval = lcd_busy_wait(info);
205		if (retval < 0)
206			break;
207
208		lcd_write_data(info, dst[len]);
209		if (pos == 0x0f)
210			pos = 0x40;
211		else
212			pos++;
213	}
214
215	if (retval < 0 && signal_pending(current))
216		return -ERESTARTSYS;
217
218	*ppos += len;
219
220	return len;
221}
222
223static int cobalt_lcdfb_blank(int blank_mode, struct fb_info *info)
224{
225	int retval;
226
227	retval = lcd_busy_wait(info);
228	if (retval < 0)
229		return retval;
230
231	switch (blank_mode) {
232	case FB_BLANK_UNBLANK:
233		lcd_write_control(info, LCD_ON);
234		break;
235	default:
236		lcd_write_control(info, LCD_OFF);
237		break;
238	}
239
240	return 0;
241}
242
243static int cobalt_lcdfb_cursor(struct fb_info *info, struct fb_cursor *cursor)
244{
245	u32 x, y;
246	int retval;
247
248	switch (cursor->set) {
249	case FB_CUR_SETPOS:
250		x = cursor->image.dx;
251		y = cursor->image.dy;
252		if (x >= LCD_XRES_MAX || y >= LCD_YRES_MAX)
253			return -EINVAL;
254
255		retval = lcd_busy_wait(info);
256		if (retval < 0)
257			return retval;
258
259		lcd_write_control(info,
260				  LCD_TEXT_POS(info->fix.line_length * y + x));
261		break;
262	default:
263		return -EINVAL;
264	}
265
266	retval = lcd_busy_wait(info);
267	if (retval < 0)
268		return retval;
269
270	if (cursor->enable)
271		lcd_write_control(info, LCD_CURSOR_ON);
272	else
273		lcd_write_control(info, LCD_CURSOR_OFF);
274
275	return 0;
276}
277
278static const struct fb_ops cobalt_lcd_fbops = {
279	.owner		= THIS_MODULE,
280	.fb_read	= cobalt_lcdfb_read,
281	.fb_write	= cobalt_lcdfb_write,
282	.fb_blank	= cobalt_lcdfb_blank,
283	__FB_DEFAULT_IOMEM_OPS_DRAW,
284	.fb_cursor	= cobalt_lcdfb_cursor,
285	__FB_DEFAULT_IOMEM_OPS_MMAP,
286};
287
288static int cobalt_lcdfb_probe(struct platform_device *dev)
289{
290	struct fb_info *info;
291	struct resource *res;
292	int retval;
293
294	info = framebuffer_alloc(0, &dev->dev);
295	if (!info)
296		return -ENOMEM;
297
298	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
299	if (!res) {
300		framebuffer_release(info);
301		return -EBUSY;
302	}
303
304	info->screen_size = resource_size(res);
305	info->screen_base = devm_ioremap(&dev->dev, res->start,
306					 info->screen_size);
307	if (!info->screen_base) {
308		framebuffer_release(info);
309		return -ENOMEM;
310	}
311
312	info->fbops = &cobalt_lcd_fbops;
313	info->fix = cobalt_lcdfb_fix;
314	info->fix.smem_start = res->start;
315	info->fix.smem_len = info->screen_size;
316	info->pseudo_palette = NULL;
317	info->par = NULL;
318
319	retval = register_framebuffer(info);
320	if (retval < 0) {
321		framebuffer_release(info);
322		return retval;
323	}
324
325	platform_set_drvdata(dev, info);
326
327	lcd_clear(info);
328
329	fb_info(info, "Cobalt server LCD frame buffer device\n");
330
331	return 0;
332}
333
334static void cobalt_lcdfb_remove(struct platform_device *dev)
335{
336	struct fb_info *info;
337
338	info = platform_get_drvdata(dev);
339	if (info) {
340		unregister_framebuffer(info);
341		framebuffer_release(info);
342	}
343}
344
345static struct platform_driver cobalt_lcdfb_driver = {
346	.probe	= cobalt_lcdfb_probe,
347	.remove_new = cobalt_lcdfb_remove,
348	.driver	= {
349		.name	= "cobalt-lcd",
350	},
351};
352module_platform_driver(cobalt_lcdfb_driver);
353
354MODULE_LICENSE("GPL v2");
355MODULE_AUTHOR("Yoichi Yuasa");
356MODULE_DESCRIPTION("Cobalt server LCD frame buffer driver");
357