1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * FB driver for Two KS0108 LCD controllers in AGM1264K-FL display
4  *
5  * Copyright (C) 2014 ololoshka2871
6  */
7 
8 #include <linux/module.h>
9 #include <linux/kernel.h>
10 #include <linux/init.h>
11 #include <linux/gpio/consumer.h>
12 #include <linux/delay.h>
13 #include <linux/slab.h>
14 
15 #include "fbtft.h"
16 
17 /* Uncomment text line to use negative image on display */
18 /*#define NEGATIVE*/
19 
20 #define WHITE		0xff
21 #define BLACK		0
22 
23 #define DRVNAME		"fb_agm1264k-fl"
24 #define WIDTH		64
25 #define HEIGHT		64
26 #define TOTALWIDTH	(WIDTH * 2)	 /* because 2 x ks0108 in one display */
27 #define FPS			20
28 
29 #define EPIN		gpio.wr
30 #define RS			gpio.dc
31 #define RW			gpio.aux[2]
32 #define CS0			gpio.aux[0]
33 #define CS1			gpio.aux[1]
34 
35 /* diffusing error (Floyd-Steinberg) */
36 #define DIFFUSING_MATRIX_WIDTH	2
37 #define DIFFUSING_MATRIX_HEIGHT	2
38 
39 static const signed char
40 diffusing_matrix[DIFFUSING_MATRIX_WIDTH][DIFFUSING_MATRIX_HEIGHT] = {
41 	{-1, 3},
42 	{3, 2},
43 };
44 
45 static const unsigned char gamma_correction_table[] = {
46 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1,
47 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6,
48 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 11, 11, 11, 12, 12, 13,
49 13, 13, 14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21,
50 22, 22, 23, 23, 24, 25, 25, 26, 26, 27, 28, 28, 29, 30, 30, 31, 32,
51 33, 33, 34, 35, 35, 36, 37, 38, 39, 39, 40, 41, 42, 43, 43, 44, 45,
52 46, 47, 48, 49, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
53 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 81,
54 82, 83, 84, 85, 87, 88, 89, 90, 91, 93, 94, 95, 97, 98, 99, 100, 102,
55 103, 105, 106, 107, 109, 110, 111, 113, 114, 116, 117, 119, 120, 121,
56 123, 124, 126, 127, 129, 130, 132, 133, 135, 137, 138, 140, 141, 143,
57 145, 146, 148, 149, 151, 153, 154, 156, 158, 159, 161, 163, 165, 166,
58 168, 170, 172, 173, 175, 177, 179, 181, 182, 184, 186, 188, 190, 192,
59 194, 196, 197, 199, 201, 203, 205, 207, 209, 211, 213, 215, 217, 219,
60 221, 223, 225, 227, 229, 231, 234, 236, 238, 240, 242, 244, 246, 248,
61 251, 253, 255
62 };
63 
init_display(struct fbtft_par * par)64 static int init_display(struct fbtft_par *par)
65 {
66 	u8 i;
67 
68 	par->fbtftops.reset(par);
69 
70 	for (i = 0; i < 2; ++i) {
71 		write_reg(par, i, 0x3f); /* display on */
72 		write_reg(par, i, 0x40); /* set x to 0 */
73 		write_reg(par, i, 0xb0); /* set page to 0 */
74 		write_reg(par, i, 0xc0); /* set start line to 0 */
75 	}
76 
77 	return 0;
78 }
79 
80 /* Check if all necessary GPIOS defined */
verify_gpios(struct fbtft_par * par)81 static int verify_gpios(struct fbtft_par *par)
82 {
83 	int i;
84 
85 	dev_dbg(par->info->device,
86 		"%s()\n", __func__);
87 
88 	if (!par->EPIN) {
89 		dev_err(par->info->device,
90 			"Missing info about 'wr' (aka E) gpio. Aborting.\n");
91 		return -EINVAL;
92 	}
93 	for (i = 0; i < 8; ++i) {
94 		if (!par->gpio.db[i]) {
95 			dev_err(par->info->device,
96 				"Missing info about 'db[%i]' gpio. Aborting.\n",
97 				i);
98 			return -EINVAL;
99 		}
100 	}
101 	if (!par->CS0) {
102 		dev_err(par->info->device,
103 			"Missing info about 'cs0' gpio. Aborting.\n");
104 		return -EINVAL;
105 	}
106 	if (!par->CS1) {
107 		dev_err(par->info->device,
108 			"Missing info about 'cs1' gpio. Aborting.\n");
109 		return -EINVAL;
110 	}
111 	if (!par->RW) {
112 		dev_err(par->info->device,
113 			"Missing info about 'rw' gpio. Aborting.\n");
114 		return -EINVAL;
115 	}
116 
117 	return 0;
118 }
119 
120 static unsigned long
request_gpios_match(struct fbtft_par * par,const struct fbtft_gpio * gpio)121 request_gpios_match(struct fbtft_par *par, const struct fbtft_gpio *gpio)
122 {
123 	dev_dbg(par->info->device,
124 		"%s('%s')\n", __func__, gpio->name);
125 
126 	if (strcasecmp(gpio->name, "wr") == 0) {
127 		/* left ks0108 E pin */
128 		par->EPIN = gpio->gpio;
129 		return GPIOD_OUT_LOW;
130 	} else if (strcasecmp(gpio->name, "cs0") == 0) {
131 		/* left ks0108 controller pin */
132 		par->CS0 = gpio->gpio;
133 		return GPIOD_OUT_HIGH;
134 	} else if (strcasecmp(gpio->name, "cs1") == 0) {
135 		/* right ks0108 controller pin */
136 		par->CS1 = gpio->gpio;
137 		return GPIOD_OUT_HIGH;
138 	}
139 
140 	/* if write (rw = 0) e(1->0) perform write */
141 	/* if read (rw = 1) e(0->1) set data on D0-7*/
142 	else if (strcasecmp(gpio->name, "rw") == 0) {
143 		par->RW = gpio->gpio;
144 		return GPIOD_OUT_LOW;
145 	}
146 
147 	return FBTFT_GPIO_NO_MATCH;
148 }
149 
150 /* This function oses to enter commands
151  * first byte - destination controller 0 or 1
152  * following - commands
153  */
write_reg8_bus8(struct fbtft_par * par,int len,...)154 static void write_reg8_bus8(struct fbtft_par *par, int len, ...)
155 {
156 	va_list args;
157 	int i, ret;
158 	u8 *buf = par->buf;
159 
160 	if (unlikely(par->debug & DEBUG_WRITE_REGISTER)) {
161 		va_start(args, len);
162 		for (i = 0; i < len; i++)
163 			buf[i] = (u8)va_arg(args, unsigned int);
164 
165 		va_end(args);
166 		fbtft_par_dbg_hex(DEBUG_WRITE_REGISTER, par, par->info->device,
167 				  u8, buf, len, "%s: ", __func__);
168 }
169 
170 	va_start(args, len);
171 
172 	*buf = (u8)va_arg(args, unsigned int);
173 
174 	if (*buf > 1) {
175 		va_end(args);
176 		dev_err(par->info->device,
177 			"Incorrect chip select request (%d)\n", *buf);
178 		return;
179 	}
180 
181 	/* select chip */
182 	if (*buf) {
183 		/* cs1 */
184 		gpiod_set_value(par->CS0, 0);
185 		gpiod_set_value(par->CS1, 1);
186 	} else {
187 		/* cs0 */
188 		gpiod_set_value(par->CS0, 1);
189 		gpiod_set_value(par->CS1, 0);
190 	}
191 
192 	gpiod_set_value(par->RS, 0); /* RS->0 (command mode) */
193 	len--;
194 
195 	if (len) {
196 		i = len;
197 		while (i--)
198 			*buf++ = (u8)va_arg(args, unsigned int);
199 		ret = par->fbtftops.write(par, par->buf, len * (sizeof(u8)));
200 		if (ret < 0) {
201 			va_end(args);
202 			dev_err(par->info->device,
203 				"write() failed and returned %d\n", ret);
204 			return;
205 		}
206 	}
207 
208 	va_end(args);
209 }
210 
211 static struct
212 {
213 	int xs, ys_page, xe, ye_page;
214 } addr_win;
215 
216 /* save display writing zone */
set_addr_win(struct fbtft_par * par,int xs,int ys,int xe,int ye)217 static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
218 {
219 	addr_win.xs = xs;
220 	addr_win.ys_page = ys / 8;
221 	addr_win.xe = xe;
222 	addr_win.ye_page = ye / 8;
223 }
224 
225 static void
construct_line_bitmap(struct fbtft_par * par,u8 * dest,signed short * src,int xs,int xe,int y)226 construct_line_bitmap(struct fbtft_par *par, u8 *dest, signed short *src,
227 		      int xs, int xe, int y)
228 {
229 	int x, i;
230 
231 	for (x = xs; x < xe; ++x) {
232 		u8 res = 0;
233 
234 		for (i = 0; i < 8; i++)
235 			if (src[(y * 8 + i) * par->info->var.xres + x])
236 				res |= 1 << i;
237 #ifdef NEGATIVE
238 		*dest++ = res;
239 #else
240 		*dest++ = ~res;
241 #endif
242 	}
243 }
244 
iterate_diffusion_matrix(u32 xres,u32 yres,int x,int y,signed short * convert_buf,signed short pixel,signed short error)245 static void iterate_diffusion_matrix(u32 xres, u32 yres, int x,
246 				     int y, signed short *convert_buf,
247 				     signed short pixel, signed short error)
248 {
249 	u16 i, j;
250 
251 	/* diffusion matrix row */
252 	for (i = 0; i < DIFFUSING_MATRIX_WIDTH; ++i)
253 		/* diffusion matrix column */
254 		for (j = 0; j < DIFFUSING_MATRIX_HEIGHT; ++j) {
255 			signed short *write_pos;
256 			signed char coeff;
257 
258 			/* skip pixels out of zone */
259 			if (x + i < 0 || x + i >= xres || y + j >= yres)
260 				continue;
261 			write_pos = &convert_buf[(y + j) * xres + x + i];
262 			coeff = diffusing_matrix[i][j];
263 			if (-1 == coeff) {
264 				/* pixel itself */
265 				*write_pos = pixel;
266 			} else {
267 				signed short p = *write_pos + error * coeff;
268 
269 				if (p > WHITE)
270 					p = WHITE;
271 				if (p < BLACK)
272 					p = BLACK;
273 				*write_pos = p;
274 			}
275 		}
276 }
277 
write_vmem(struct fbtft_par * par,size_t offset,size_t len)278 static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
279 {
280 	u16 *vmem16 = (u16 *)par->info->screen_buffer;
281 	u8 *buf = par->txbuf.buf;
282 	int x, y;
283 	int ret = 0;
284 
285 	/* buffer to convert RGB565 -> grayscale16 -> Dithered image 1bpp */
286 	signed short *convert_buf = kmalloc_array(par->info->var.xres *
287 		par->info->var.yres, sizeof(signed short), GFP_NOIO);
288 
289 	if (!convert_buf)
290 		return -ENOMEM;
291 
292 	/* converting to grayscale16 */
293 	for (x = 0; x < par->info->var.xres; ++x)
294 		for (y = 0; y < par->info->var.yres; ++y) {
295 			u16 pixel = vmem16[y *  par->info->var.xres + x];
296 			u16 b = pixel & 0x1f;
297 			u16 g = (pixel & (0x3f << 5)) >> 5;
298 			u16 r = (pixel & (0x1f << (5 + 6))) >> (5 + 6);
299 
300 			pixel = (299 * r + 587 * g + 114 * b) / 200;
301 			if (pixel > 255)
302 				pixel = 255;
303 
304 			/* gamma-correction by table */
305 			convert_buf[y *  par->info->var.xres + x] =
306 				(signed short)gamma_correction_table[pixel];
307 		}
308 
309 	/* Image Dithering */
310 	for (x = 0; x < par->info->var.xres; ++x)
311 		for (y = 0; y < par->info->var.yres; ++y) {
312 			signed short pixel =
313 				convert_buf[y *  par->info->var.xres + x];
314 			signed short error_b = pixel - BLACK;
315 			signed short error_w = pixel - WHITE;
316 			signed short error;
317 
318 			/* what color close? */
319 			if (abs(error_b) >= abs(error_w)) {
320 				/* white */
321 				error = error_w;
322 				pixel = 0xff;
323 			} else {
324 				/* black */
325 				error = error_b;
326 				pixel = 0;
327 			}
328 
329 			error /= 8;
330 
331 			iterate_diffusion_matrix(par->info->var.xres,
332 						 par->info->var.yres,
333 						 x, y, convert_buf,
334 						 pixel, error);
335 		}
336 
337 	/* 1 string = 2 pages */
338 	for (y = addr_win.ys_page; y <= addr_win.ye_page; ++y) {
339 		/* left half of display */
340 		if (addr_win.xs < par->info->var.xres / 2) {
341 			construct_line_bitmap(par, buf, convert_buf,
342 					      addr_win.xs,
343 					      par->info->var.xres / 2, y);
344 
345 			len = par->info->var.xres / 2 - addr_win.xs;
346 
347 			/* select left side (sc0)
348 			 * set addr
349 			 */
350 			write_reg(par, 0x00, BIT(6) | (u8)addr_win.xs);
351 			write_reg(par, 0x00, (0x17 << 3) | (u8)y);
352 
353 			/* write bitmap */
354 			gpiod_set_value(par->RS, 1); /* RS->1 (data mode) */
355 			ret = par->fbtftops.write(par, buf, len);
356 			if (ret < 0)
357 				dev_err(par->info->device,
358 					"write failed and returned: %d\n",
359 					ret);
360 		}
361 		/* right half of display */
362 		if (addr_win.xe >= par->info->var.xres / 2) {
363 			construct_line_bitmap(par, buf,
364 					      convert_buf,
365 					      par->info->var.xres / 2,
366 					      addr_win.xe + 1, y);
367 
368 			len = addr_win.xe + 1 - par->info->var.xres / 2;
369 
370 			/* select right side (sc1)
371 			 * set addr
372 			 */
373 			write_reg(par, 0x01, BIT(6));
374 			write_reg(par, 0x01, (0x17 << 3) | (u8)y);
375 
376 			/* write bitmap */
377 			gpiod_set_value(par->RS, 1); /* RS->1 (data mode) */
378 			par->fbtftops.write(par, buf, len);
379 			if (ret < 0)
380 				dev_err(par->info->device,
381 					"write failed and returned: %d\n",
382 					ret);
383 		}
384 	}
385 	kfree(convert_buf);
386 
387 	gpiod_set_value(par->CS0, 0);
388 	gpiod_set_value(par->CS1, 0);
389 
390 	return ret;
391 }
392 
write(struct fbtft_par * par,void * buf,size_t len)393 static int write(struct fbtft_par *par, void *buf, size_t len)
394 {
395 	fbtft_par_dbg_hex(DEBUG_WRITE, par, par->info->device, u8, buf, len,
396 			  "%s(len=%zu): ", __func__, len);
397 
398 	gpiod_set_value(par->RW, 0); /* set write mode */
399 
400 	while (len--) {
401 		u8 i, data;
402 
403 		data = *(u8 *)buf++;
404 
405 		/* set data bus */
406 		for (i = 0; i < 8; ++i)
407 			gpiod_set_value(par->gpio.db[i], data & (1 << i));
408 		/* set E */
409 		gpiod_set_value(par->EPIN, 0);
410 		udelay(5);
411 		/* unset E - write */
412 		gpiod_set_value(par->EPIN, 1);
413 		udelay(1);
414 	}
415 
416 	return 0;
417 }
418 
419 static struct fbtft_display display = {
420 	.regwidth = 8,
421 	.width = TOTALWIDTH,
422 	.height = HEIGHT,
423 	.fps = FPS,
424 	.fbtftops = {
425 		.init_display = init_display,
426 		.set_addr_win = set_addr_win,
427 		.verify_gpios = verify_gpios,
428 		.request_gpios_match = request_gpios_match,
429 		.write = write,
430 		.write_register = write_reg8_bus8,
431 		.write_vmem = write_vmem,
432 	},
433 };
434 
435 FBTFT_REGISTER_DRIVER(DRVNAME, "displaytronic,fb_agm1264k-fl", &display);
436 
437 MODULE_ALIAS("platform:" DRVNAME);
438 
439 MODULE_DESCRIPTION("Two KS0108 LCD controllers in AGM1264K-FL display");
440 MODULE_AUTHOR("ololoshka2871");
441 MODULE_LICENSE("GPL");
442