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 	pos = *ppos;
133 	if (pos >= LCD_CHARS_MAX || count == 0)
134 		return 0;
135 
136 	if (count > LCD_CHARS_MAX)
137 		count = LCD_CHARS_MAX;
138 
139 	if (pos + count > LCD_CHARS_MAX)
140 		count = LCD_CHARS_MAX - pos;
141 
142 	for (len = 0; len < count; len++) {
143 		retval = lcd_busy_wait(info);
144 		if (retval < 0)
145 			break;
146 
147 		lcd_write_control(info, LCD_TEXT_POS(pos));
148 
149 		retval = lcd_busy_wait(info);
150 		if (retval < 0)
151 			break;
152 
153 		src[len] = lcd_read_data(info);
154 		if (pos == 0x0f)
155 			pos = 0x40;
156 		else
157 			pos++;
158 	}
159 
160 	if (retval < 0 && signal_pending(current))
161 		return -ERESTARTSYS;
162 
163 	if (copy_to_user(buf, src, len))
164 		return -EFAULT;
165 
166 	*ppos += len;
167 
168 	return len;
169 }
170 
171 static ssize_t cobalt_lcdfb_write(struct fb_info *info, const char __user *buf,
172 				  size_t count, loff_t *ppos)
173 {
174 	char dst[LCD_CHARS_MAX];
175 	unsigned long pos;
176 	int len, retval = 0;
177 
178 	pos = *ppos;
179 	if (pos >= LCD_CHARS_MAX || count == 0)
180 		return 0;
181 
182 	if (count > LCD_CHARS_MAX)
183 		count = LCD_CHARS_MAX;
184 
185 	if (pos + count > LCD_CHARS_MAX)
186 		count = LCD_CHARS_MAX - pos;
187 
188 	if (copy_from_user(dst, buf, count))
189 		return -EFAULT;
190 
191 	for (len = 0; len < count; len++) {
192 		retval = lcd_busy_wait(info);
193 		if (retval < 0)
194 			break;
195 
196 		lcd_write_control(info, LCD_TEXT_POS(pos));
197 
198 		retval = lcd_busy_wait(info);
199 		if (retval < 0)
200 			break;
201 
202 		lcd_write_data(info, dst[len]);
203 		if (pos == 0x0f)
204 			pos = 0x40;
205 		else
206 			pos++;
207 	}
208 
209 	if (retval < 0 && signal_pending(current))
210 		return -ERESTARTSYS;
211 
212 	*ppos += len;
213 
214 	return len;
215 }
216 
217 static int cobalt_lcdfb_blank(int blank_mode, struct fb_info *info)
218 {
219 	int retval;
220 
221 	retval = lcd_busy_wait(info);
222 	if (retval < 0)
223 		return retval;
224 
225 	switch (blank_mode) {
226 	case FB_BLANK_UNBLANK:
227 		lcd_write_control(info, LCD_ON);
228 		break;
229 	default:
230 		lcd_write_control(info, LCD_OFF);
231 		break;
232 	}
233 
234 	return 0;
235 }
236 
237 static int cobalt_lcdfb_cursor(struct fb_info *info, struct fb_cursor *cursor)
238 {
239 	u32 x, y;
240 	int retval;
241 
242 	switch (cursor->set) {
243 	case FB_CUR_SETPOS:
244 		x = cursor->image.dx;
245 		y = cursor->image.dy;
246 		if (x >= LCD_XRES_MAX || y >= LCD_YRES_MAX)
247 			return -EINVAL;
248 
249 		retval = lcd_busy_wait(info);
250 		if (retval < 0)
251 			return retval;
252 
253 		lcd_write_control(info,
254 				  LCD_TEXT_POS(info->fix.line_length * y + x));
255 		break;
256 	default:
257 		return -EINVAL;
258 	}
259 
260 	retval = lcd_busy_wait(info);
261 	if (retval < 0)
262 		return retval;
263 
264 	if (cursor->enable)
265 		lcd_write_control(info, LCD_CURSOR_ON);
266 	else
267 		lcd_write_control(info, LCD_CURSOR_OFF);
268 
269 	return 0;
270 }
271 
272 static struct fb_ops cobalt_lcd_fbops = {
273 	.owner		= THIS_MODULE,
274 	.fb_read	= cobalt_lcdfb_read,
275 	.fb_write	= cobalt_lcdfb_write,
276 	.fb_blank	= cobalt_lcdfb_blank,
277 	.fb_cursor	= cobalt_lcdfb_cursor,
278 };
279 
280 static int cobalt_lcdfb_probe(struct platform_device *dev)
281 {
282 	struct fb_info *info;
283 	struct resource *res;
284 	int retval;
285 
286 	info = framebuffer_alloc(0, &dev->dev);
287 	if (!info)
288 		return -ENOMEM;
289 
290 	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
291 	if (!res) {
292 		framebuffer_release(info);
293 		return -EBUSY;
294 	}
295 
296 	info->screen_size = resource_size(res);
297 	info->screen_base = devm_ioremap(&dev->dev, res->start,
298 					 info->screen_size);
299 	if (!info->screen_base) {
300 		framebuffer_release(info);
301 		return -ENOMEM;
302 	}
303 
304 	info->fbops = &cobalt_lcd_fbops;
305 	info->fix = cobalt_lcdfb_fix;
306 	info->fix.smem_start = res->start;
307 	info->fix.smem_len = info->screen_size;
308 	info->pseudo_palette = NULL;
309 	info->par = NULL;
310 	info->flags = FBINFO_DEFAULT;
311 
312 	retval = register_framebuffer(info);
313 	if (retval < 0) {
314 		framebuffer_release(info);
315 		return retval;
316 	}
317 
318 	platform_set_drvdata(dev, info);
319 
320 	lcd_clear(info);
321 
322 	fb_info(info, "Cobalt server LCD frame buffer device\n");
323 
324 	return 0;
325 }
326 
327 static int cobalt_lcdfb_remove(struct platform_device *dev)
328 {
329 	struct fb_info *info;
330 
331 	info = platform_get_drvdata(dev);
332 	if (info) {
333 		unregister_framebuffer(info);
334 		framebuffer_release(info);
335 	}
336 
337 	return 0;
338 }
339 
340 static struct platform_driver cobalt_lcdfb_driver = {
341 	.probe	= cobalt_lcdfb_probe,
342 	.remove	= cobalt_lcdfb_remove,
343 	.driver	= {
344 		.name	= "cobalt-lcd",
345 	},
346 };
347 module_platform_driver(cobalt_lcdfb_driver);
348 
349 MODULE_LICENSE("GPL v2");
350 MODULE_AUTHOR("Yoichi Yuasa");
351 MODULE_DESCRIPTION("Cobalt server LCD frame buffer driver");
352