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 
54 static inline void lcd_write_control(struct fb_info *info, u8 control)
55 {
56 	writel((u32)control << 24, info->screen_base);
57 }
58 
59 static inline u8 lcd_read_control(struct fb_info *info)
60 {
61 	return readl(info->screen_base) >> 24;
62 }
63 
64 static 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 
69 static inline u8 lcd_read_data(struct fb_info *info)
70 {
71 	return readl(info->screen_base + LCD_DATA_REG_OFFSET) >> 24;
72 }
73 
74 static 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 
97 static 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 
116 static 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 
125 static 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 
174 static 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 
223 static 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 
243 static 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 
278 static 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_cursor	= cobalt_lcdfb_cursor,
284 };
285 
286 static int cobalt_lcdfb_probe(struct platform_device *dev)
287 {
288 	struct fb_info *info;
289 	struct resource *res;
290 	int retval;
291 
292 	info = framebuffer_alloc(0, &dev->dev);
293 	if (!info)
294 		return -ENOMEM;
295 
296 	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
297 	if (!res) {
298 		framebuffer_release(info);
299 		return -EBUSY;
300 	}
301 
302 	info->screen_size = resource_size(res);
303 	info->screen_base = devm_ioremap(&dev->dev, res->start,
304 					 info->screen_size);
305 	if (!info->screen_base) {
306 		framebuffer_release(info);
307 		return -ENOMEM;
308 	}
309 
310 	info->fbops = &cobalt_lcd_fbops;
311 	info->fix = cobalt_lcdfb_fix;
312 	info->fix.smem_start = res->start;
313 	info->fix.smem_len = info->screen_size;
314 	info->pseudo_palette = NULL;
315 	info->par = NULL;
316 
317 	retval = register_framebuffer(info);
318 	if (retval < 0) {
319 		framebuffer_release(info);
320 		return retval;
321 	}
322 
323 	platform_set_drvdata(dev, info);
324 
325 	lcd_clear(info);
326 
327 	fb_info(info, "Cobalt server LCD frame buffer device\n");
328 
329 	return 0;
330 }
331 
332 static void cobalt_lcdfb_remove(struct platform_device *dev)
333 {
334 	struct fb_info *info;
335 
336 	info = platform_get_drvdata(dev);
337 	if (info) {
338 		unregister_framebuffer(info);
339 		framebuffer_release(info);
340 	}
341 }
342 
343 static struct platform_driver cobalt_lcdfb_driver = {
344 	.probe	= cobalt_lcdfb_probe,
345 	.remove_new = cobalt_lcdfb_remove,
346 	.driver	= {
347 		.name	= "cobalt-lcd",
348 	},
349 };
350 module_platform_driver(cobalt_lcdfb_driver);
351 
352 MODULE_LICENSE("GPL v2");
353 MODULE_AUTHOR("Yoichi Yuasa");
354 MODULE_DESCRIPTION("Cobalt server LCD frame buffer driver");
355